bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A39: PI3K inhibition in preclinical models of HNSCC
Authors: Hedberg Matthew Louis , Li Hua , Zeng Yan , Grandis Jennifer Rubin
Published: October 2015

Head and neck squamous cell carcinoma (HNSCC) is characterized by alteration of the PI3K pathway; especially mutation and/or amplification of the oncogene PIK3CA, and these alterations are enriched in HNSCC associated with human papilloma virus infection (HPV(+)HNSCC). We sought to test the hypothesis that HNSCC cells/tumors with mutant or amplified PIK3CA are more sensitive to anti-tumor effects of PI3K pathway inhibitors, including BKM-120 and BYL-719, and to assess the effect of HPV status on the efficacy of these agents. Proliferation assays and immunobloting were employed to examine the effects on growth and signaling of BKM-120 and BYL-719 administration to HNSCC cell lines with endogenous PIK3CA mutation, gene amplification, or WT, unamplified PIK3CA. The cytotoxic effects of BKM-120 and BYL-719 were comparable in a panel of 8 HNSCC cell lines, with IC50s in the micromolar range. BYL-719 demonstrated greater cytotoxic activity in cell lines with endogenous PIK3CA alterations compared with cells harboring endogenous WT, unamplified PIK3CA. Treatment with BKM-120 decreased the levels of phosphorylated AKT in a dose-dependent fashion to a greater degree in PIK3CA altered cells than in PIK3CA WT cells. In contrast, BYL-719 treatment inhibited phosphorylation of AKT in both PIK3CA altered and PIK3CA WT HNSCC cells, with comparable efficacy. Phosphorylation of S6 and MTOR however, was inhibited by BYL-719 to a greater degree in PIK3CA altered cell lines vs. PIK3CA WT cell lines. More than half of all HPV(+)HNSCC harbor some form of PI3K alteration; generally PIK3CA mutation or amplification. However, there is a paucity of HPV(+)HNSCC cell lines, and no cell lines to date derived from HPV(+)HNSCC tumors contain PIK3CA mutations. Although we included two HPV(+)HNSCC cell lines in our studies, neither are known to harbor endogenous PIK3CA mutations, and they did not appear to be more sensitive to PI3K pathway targeting with BKM-120 or BYL-719. Our in vivo treatment experiments, utilizing patient derived xenografts (PDX) of varying HPV and PIK3CA status, demonstrate that the growth of HPV(+)HNSCC tumors can be inhibited by BYL-719 treatment to a greater degree than the growth of HPV(-)HNSCC tumors. These cumulative findings suggest that PI3K inhibition may represent an effective therapeutic strategy in the subset of HNSCC patients whose tumors harbor PI3K alteration. As the PI3K pathway is the most commonly altered mitogenic pathway in HNSCC; the completion of this work, and its extension into clinical trials, will likely have translational significance.

Citation Format: Matthew Louis Hedberg, Hua Li, Yan Zeng, Jennifer Rubin Grandis. PI3K inhibition in preclinical models of HNSCC. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A39.
Abstract B04: NPM1: A new downstream effector of PI3K-AKT-mTOR pathway in prostate cancer?
Authors: Boudra Rafik , Loubeau Gaelle , Lours-Calet Corinne , Dejoussineau Cyrille , Morel Laurent , Beaudoin Claude
Published: October 2015

Nucleophosmin NPM1 is a molecular chaperone involved in many aspect of cellular physiology, eg. ribosomal biogenesis and cell cycle regulation. NPM1 is overexpressed in numerous types of solid tumors, including prostate cancer but the underlying molecular mechanisms are largely unknown. Using both cell lines and transgenic mouse models, we show that NPM1 expression is significantly increased in cells where the PI3K-AKT-mTOR pathway is activated through PTEN deletion. This overexpression is reversed when cells are treated with the pharmacological inhibitor of mTOR rapamycin. In accordance, transfection of small interfering RNA (siRNA) directed against mTOR leads to mTOR and NPM1 downregulation in these cells. In vivo, we found that NPM1 is overexpressed in PTEN knock-out murine prostate, and a one week treatment of these mice with rapamycin leads to NPM1 downregulation. Chromatin Immunoprecipitation (ChIP) assays show that mTOR is localized on NPM1 proximal promoter, close to a binding site for the transcription factor Ying-Yang 1 (YY1). mTOR binding on the chromatin seems to be constitutive, since rapamycin treatment did not alter its localization. mTOR could therefore regulates NPM1 expression by phosphorylating others factors involved in NPM1 gene expression, as previously described (Cunningham et al., 2007). We have previously shown that NPM1 overexpression enhance the migration and invasion abilities of prostate cancer cells (Loubeau et al., 2014). Moreover, NPM1 overexpression in mouse prostate epithelium leads to p27 protein downregulation and cyclin E upregulation, two molecular features of aggressive human prostate cancer. We thus propose that NPM1 could be a downstream effector of PI3K-AKT-mTOR pathway, supporting prostate cancer progression by altering expression of a set of genes involved in cellular homeostasis and proliferation.

Citation Format: Rafik Boudra, Gaelle Loubeau, Corinne Lours-Calet, Cyrille Dejoussineau, Laurent Morel, Claude Beaudoin. NPM1: A new downstream effector of PI3K-AKT-mTOR pathway in prostate cancer? [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B04.
Abstract B19: Short chain fatty acids suppress mTOR activation in colon cancer cells via the long noncoding RNA rhabdomyosarcoma 2 associated transcript
Authors: Wang Jiuhui , Nie Daotai
Published: October 2015

Short chain fatty acids (SCFAs), derived from dietary fiber bacterial fermentation in the colon, exert multiple effects on colonic functions including tumor suppressing activities. Our previous studies found that SCFAs can induce autophagy in colon cancer cells via suppressing mTOR activities, but the mechanism involved is not well understood. Herein we identify rhabdomyosarcoma 2 associated transcript (RMST), a long non-coding RNA, and protein tyrosine phosphatase non-receptor type 7(PTPN7) as key mediators for SCFAs to suppress mTOR signaling. SCFAs induce the expression of RMST in colon cancer cells. RMST by itself is sufficient to suppress mTOR signaling and sensitize colon cancer cells to SCFAs induction of autophagy. Through profiling, PTPN7 was identified as an effector for both RMST and SCFAs to suppress mTOR signaling. RMST increases the expression of PTPN7 by recruiting RNAPII to its promoter region. The data delineate a novel RMST-PTPN7 cellular pathway, enlisted by SCFAs, to modulate mTOR activities.

Citation Format: Jiuhui Wang, Daotai Nie. Short chain fatty acids suppress mTOR activation in colon cancer cells via the long noncoding RNA rhabdomyosarcoma 2 associated transcript. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B19.
Abstract B23: The 5 UTR of many oncogenes and transcription factors encodes a targetable dependence on the eIF4A RNA helicase
Authors: Singh Kamini , Wolfe Andrew L. , Zhong Yi , Rätsch Gunnar , Wendel Hans-Guido
Published: October 2015

We report a mechanism of translational control that is determined by a requirement for eIF4A RNA helicase activity and underlies the anticancer effects of Silvestrol and related compounds. Briefly, activation of cap-dependent translation contributes to T-cell leukemia (T-ALL) development and maintenance. Accordingly, inhibition of translation initiation factor eIF4A with Silvestrol produces powerful therapeutic effects against T-ALL in vivo. We used transcriptome-scale ribosome footprinting on Silvestrol-treated T-ALL cells to identify Silvestrol-sensitive transcripts and the hallmark features of eIF4A-dependent translation. These include a long 5 UTR and a 12-mer sequence motif that encodes a guanine quartet (CGG)4. RNA folding algorithms as well as experimental evidences pinpoint the (CGG)4 motif as a common site of RNA G-quadruplex structures within the 5 UTR. In T-ALL these structures mark approximately eighty highly Silvestrol-sensitive transcripts that include key oncogenes and transcription factors and contribute to the drug's anti-leukemic action. Hence, the eIF4A-dependent translation of G-quadruplex containing transcripts emerges as a gene-specific and therapeutically targetable mechanism of translational control.

Citation Format: Kamini Singh, Andrew L. Wolfe, Yi Zhong, Gunnar Rätsch, Hans-Guido Wendel. The 5 UTR of many oncogenes and transcription factors encodes a targetable dependence on the eIF4A RNA helicase. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B23.
Abstract B28: Rictor/mTORC2 drives formation, progression, and therapeutic resistance of HER2-amplified breast cancers
Authors: Morrison Meghan M. , Jones Bayley A. , Hicks Donna J. , Sanchez Violeta , Estrada Valeria M. , Williams Michelle M. , Brantley-Sieders Dana , Cook Rebecca S.
Published: October 2015

Although HER2-targeted therapies substantially improve the outcome for patients with HER2-amplified breast cancer, resistance to HER2 targeting is frequently observed. HER2-amplified tumors depend on the HER2-mediated activation of the phosphatidylinositol-3kinase (PI3K)/Akt pathway, which becomes reactivated in many therapeutically resistant HER2-amplified tumors. We investigated the mTOR complexes mTORC1 and mTORC2 as potential therapeutic targets in HER2-amplified breast cancers, based on their roles as activators (mTORC2) or effectors (mTORC1) of Akt. We found that genomic gains in Rictor, encoding a necessary mTORC2 cofactor, correlated with poor survival in breast cancer patients, while genomic gains in Raptor, an mTORC1 cofactor, did not. Rictor protein levels were increased in invasive breast cancers as compared to ductal carcinoma in situ (DCIS). Conditional Rictor gene ablation decreased growth, cell survival and invasion of human HER2-amplified breast cancer cells by blocking Akt signaling. Treatment of HER2 positive cells with the HER2/EGFR inhibitor Lapatinib caused Rictor upregulation. However, Rictor knockdown improved cell killing in Lapatinib-treated cells and impaired Akt signaling and cell survival in Lapatinib-resistant HER2 positive breast cancer cells. Together, these results demonstrate the pivotal role of mTORC2 in HER2-amplified breast cancers and support efforts to develop mTORC2-targeted therapies.

Citation Format: Meghan M. Morrison, Bayley A. Jones, Donna J. Hicks, Violeta Sanchez, Valeria M. Estrada, Michelle M. Williams, Dana Brantley-Sieders, Rebecca S. Cook. Rictor/mTORC2 drives formation, progression, and therapeutic resistance of HER2-amplified breast cancers. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B28.
Abstract B37: Mechanisms of acquired resistance to the PI3K inhibitor GDC-0941 in breast cancer cell lines
Authors: Edgar Kyle A. , Hwu Ling , Walter Kimberly , Lackner Mark , Friedman Lori S. , Wallin Jeffrey J.
Published: October 2015

Alterations of the phosphoinositide-3 kinase (PI3K)/Akt signaling pathway occur broadly in cancer via multiple mechanisms including mutation of the PIK3CA gene or loss of the tumor suppressor PTEN. The dysregulation of this pathway has been implicated in tumor initiation, cell growth and survival, invasion and angiogenesis, thus, PI3K is a promising therapeutic target for cancer. There are several PI3K inhibitors in clinical trials and the current study was intended to investigate preclinical mechanisms of acquired resistance to GDC-0941, a class I selective PI3K inhibitor. GDC-0941 resistant pools and clones were generated in both EVSA-T and HCC-1954 breast cancer cell lines by treating cells with increasing concentrations of drug. We found that resistant clones from both lines demonstrated marked increase of downstream PI3K pathway signaling and upregulation of the MAPK pathway, through two different mechanisms. In HCC-1954, autocrine signaling to EGFR was observed in the resistant clones and resulted in increased dependency on the downstream factor c-Myc. EVSA-T clones with acquired resistance to GDC-0941 had elevated HER2 copy number and protein expression levels. A corresponding increase in phosphorylation of HER2 binding partner ErbB3 was also discovered in the EVSA-T resistance cells. In both cases sensitivity to PI3K inhibition was restored by blocking the activated upstream receptor tyrosine kinase, EGFR for HCC-1954 and HER2 for EVSA-T. Additionally both models were re-sensitized to GDC-0941 by blocking downstream signaling of the MAPK pathway. These preclinical data may provide rationale for combination therapy with PI3K inhibitors in the clinic.

Citation Format: Kyle A. Edgar, Ling Hwu, Kimberly Walter, Mark Lackner, Lori S. Friedman, Jeffrey J. Wallin. Mechanisms of acquired resistance to the PI3K inhibitor GDC-0941 in breast cancer cell lines. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B37.
Abstract B45: Vertical inhibition of the PI3K pathway potently sensitizes diffuse large B cell lymphoma to BCL-2 antagonism
Authors: Lee Jong-Hoon Scott , Tang Sarah , Ortiz Veronica , Fruman David A.
Published: October 2015

The PI3K/AKT/mTOR axis is one of the most commonly mutated pathways in cancer, where aberrant activation promotes cell growth, proliferation, and survival. However, selective inhibitors targeting PI3K/AKT/mTOR have been hindered by their inability to effectively induce cell death in certain cancers. With the introduction of inhibitors that directly inhibit key pro-survival factors such as BCL-2 and BCL-XL (ABT-263 and ABT-199), the potential to achieve cancer cell death using combinations of targeted inhibitors has become a realizable goal. Here we show that selective inhibition of key components in the PI3K pathway (PI3K, AKT, or mTOR) potently sensitized a panel of DLBCL cell lines to ABT-263-induced apoptosis. While the degree of sensitization varied according to which PI3K pathway component was targeted, dual inhibition of both PI3K and mTOR consistently elicited the most potent sensitization across several cell lines. Previous work in other cancer types has linked the potency of this combination to the capacity of PI3K pathway inhibitors to reduce MCL-1 in an mTORC1-dependent manner. However, we found that this was not the case for DLBCL. For example, ABT-263 resistance induced by over-expression of MCL-1 was overcome when cells were co-treated with a dual-PI3K/mTOR inhibitor NVP-BEZ235 despite maintained expression of MCL-1. Instead, inhibition of the PI3K pathway led to a general increase in mitochondrial priming as measured by BH3 profiling. This occurred through distinct effects from both AKT and mTORC1 on the abundance of multiple BCL-2 family proteins at the mitochondria including reductions in the pro-survival proteins BCL-2, MCL-1, and BCL-XL as well as increases in Bim and Bad. In addition to these direct effects on BCL-2 family proteins, we found that inhibition of the PI3K pathway reduced expression of cancer-relevant proteins c-Myc and eIF4G as determined by reverse phase protein array. Thus, this project highlights the broad effects of dual-PI3K/mTOR inhibitors that sensitize DLBCL to apoptosis, and suggests that inhibition of the PI3K pathway has distinct effects on cell survival signaling among different cancer cell types.

Citation Format: Jong-Hoon Scott Lee, Sarah Tang, Veronica Ortiz, David A. Fruman. Vertical inhibition of the PI3K pathway potently sensitizes diffuse large B cell lymphoma to BCL-2 antagonism. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B45.
Abstract IA04: PTEN regulation and output
Authors: Parsons Ramon E.
Published: October 2015

PTEN is one of the most frequently mutated and epigenetically silenced tumor suppressor genes in cancer. The PTEN gene encodes intracellular (PTEN) and secreted (PTEN-L) protein isoforms that have lipid phosphatase activity. The secreted isoform has the ability to enter cells in trans. PTEN tumor suppression occurs through PI3K-dependent and independent mechanisms. Recent progress involving PTEN function, isoforms, enzyme regulation, and attempts at therapy will be presented.

Citation Format: Ramon E. Parsons. PTEN regulation and output. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr IA04.
Abstract IA06: PI 3-kinase and Akt at the interface of signaling and metabolism
Authors: Toker Alex
Published: October 2015

The PI 3-Kinase and Akt signaling pathway plays a critical role in modulating all phenotypes associated with human malignancies, including cell survival, proliferation and metabolism. Recent studies point to a major role for Akt signaling in modulating changes in metabolic pathways, although the specific mechanisms are unknown. Using unbiased metabolic profiling, we have uncovered a role for oncogenic PI 3-K and Akt in sensing redox changes in cancer cells, specifically by up-regulating glutathione levels and enhancing glutathione biosynthetic flux. Mechanistically, this is mediated by mTORC1-mediated up-regulation of the oxidative pentose phosphate pathway and Nrf2 activation. These findings indicate a post-translational mechanism by which oncogenic Akt signaling directly activates Nrf2 in cancer. Enhanced glutathione biosynthesis provides several advantages to cancer cells, including oxidative stress resistance and anchorage-independent growth, and thus constitute a metabolic dependency that can be targeted as a therapeutic strategy within breast cancer cells driven by Akt hyperactivation. In a separate study, we show that the chemotherapy agent doxorubicin triggers rapid and sustained activation of Akt signaling in breast cancer lines. Small molecule inhibitors of PI3K or Akt block Akt signaling downstream of DNA damage and sensitize cells to the cytotoxicity of doxorubicin. We have identified MERIT40, a component of the BRCA1-A DNA damage repair complex, as a novel Akt substrate that is phosphorylated in doxorubicin-treated cells. MERIT40 phosphorylation is required for formation and stabilization of the multicomponent BRCA1-A complex in response to DNA damage and this contributes to the resolution of DNA damage. We propose that disruption of MERIT40 phosphorylation contributes to the ability of PI3K/Akt inhibitors to sensitize breast cancer cells to chemotherapy through disruption of BRCA1 A complex integrity which is required for DNA damage repair and cell survival in the DNA damage response.

Citation Format: Alex Toker. PI 3-kinase and Akt at the interface of signaling and metabolism. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr IA06.
Abstract IA15: New insights on the role of tumor suppressor phosphatases
Authors: Pandolfi Pier Paolo
Published: October 2015

Because of the critical tumor suppressive role PTEN, its multiple layers of regulation have been the subject of intense investigation. Through its ability to dephosphorylate phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) PTEN suppresses the activation of the PI3K pathway. Its loss in turn results in the aberrant hyper-activation of AKT-mTOR signaling. Deletion, silencing and mutation of the PTEN phosphatase represents one of the most frequent events in human tumorigenesis. Reductions in PTEN levels are also tremendously consequential, resulting in cancer susceptibility and overt tumorigenesis in a cell type specific manner. In keeping with this notion PTEN is also found mutated in the germ line of individuals affected by PTEN Hamartoma Syndromes, characterized by developmental defects and cancer susceptibility. INPP4b, on the other hand, is an inositol polyphosphate-4-phosphatase, type II, that dephosphorylates the phosphate group at position 4 of the inositol ring from inositol 3,4-bisphosphate. In so doing, INPP4b, like PTEN, can oppose the activation of the PI3K-Akt pathway. The INPP4b gene has been recently found frequently deleted in human cancers. On this basis we started investigating its putative tumor suppressive role both in vitro and in vivo in mouse models. Novel data emerging from the analysis of the critical role of these phosphatases in human cancer and disease pathogenesis will be presented.

Citation Format: Pier Paolo Pandolfi. New insights on the role of tumor suppressor phosphatases. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr IA15.
Abstract IA28: PI3K and mTOR inhibitors in lymphoid malignancies: Clinical data
Authors: Leonard John P.
Published: October 2015

Activation of pathways associated with PI3 Kinase and mTOR is commonly associated with a variety of lymphoid cancers, and can result in cell survival, growth and resistance to standard chemoimmunotherapeutics. Strong preclinical rationale has led to several agents that have been evaluated in clinical trials, both as monotherapy and in combination strategies. The mTOR inhibitors everolimus Iand temsirolimus have demonstrated clear clinical activity and acceptable toxicity profiles in patients with a variety of lymphoid malignancies. Temsirolimus has been approved in the European Union and several other countries outside of the US for the treatment of relapsed and/or refractory mantle cell lymphoma. This approval was based on a phase 3 randomized trial comparing temsirolimus at 2 dosing levels vs. investigator's therapy choice, which demonstrated an improvement in progression-free survival and overall response rate. Single agent activity of temsirolimus has also been demonstrated in other lymphoma subtypes such as diffuse large B cell and follicular lymphoma, and combination studies have been performed with rituximab. Everolimus has also been evaluated in mantle cell, diffuse large B cell and follicular lymphoma, as well as Hodgkin lymphoma, and clinical activity has also been noted. Combination studies with histone deacetylase inhibitors, rituximab and lenalidomide are underway. To date, activity of PI3K inhibitors appears to be most significant in lymphoid malignancies. Idelalisib, an inhibitor of the PI3K delta isoform, is FDA approved as a single agent for patients with follicular lymphoma and small lymphocytic lymphoma, and in combination with rituximab for recurrent chronic lymphocytic leukemia. Responses have been noted in mantle cell lymphoma, though durability is short. Numerous combination studies with chemotherapy and rituximab are ongoing. IPI-145 is an oral inhibitor of the delta and gamma isoforms of PI3K, and early studies have shown activity in both indolent B cell lymphomas as well as T cell histologies. The alpha and delta PI3K inhibitor copanlisib has also demonstrated early activity in a range of lymphoid histologies. The clinical activity and toxicity profile of PI3K inhibitors has suggested a significant potential role for these agents in the treatment of various lymphoproliferative cancers. Ongoing studies are evaluating potential biomarkers for response and resistance, as well as the development of rational combination approaches. Clinical findings suggest at this stage that targeting mTOR and PI3K represents a valuable therapeutic approach in lymphoma and that further investigation in this area will lead to further progress in improving patient outcomes.

Citation Format: John P. Leonard. PI3K and mTOR inhibitors in lymphoid malignancies: Clinical data. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr IA28.
Abstract A01: Genome-wide changes in expression of small RNAs in human testis cancer tissue
Authors: Rounge Trine Ballestad , Furu Kari , Skotheim Rolf Inge , Enerly Espen , Haugen Trine Berit , Grotmol Tom
Published: October 2015

Testicular germ cell tumor (TGCT) is the most common malignancy in young men in most western countries. The incidence is highest in Northern European populations, where the incidence rates have increased significantly over the past decades. Genetic predisposition and conditions during pregnancy play a central role in TGCT development, and the disease arises from primordial germ cells that develop into carcinoma in situ (CIS) lesions. These lesions may develop into cancer from puberty onwards. Like primordial germ cells, CIS cells retain a permissive chromatin structure, indicating the involvement of epigenetic components in TGCT.

To assess the role of small RNAs in testicular carcinogenesis, we quantified small RNAs (19 to 35 bp) in 25 human cancer samples with differing TGCT histology and 12 normal testis samples using small RNA sequencing. piRNA expression levels were calculated for piRNA clusters built on the small RNA dataset generated from the 37 samples. Most piRNA clusters differ substantially in expression between TGCT samples and healthy controls, indicating a common mechanism for this genome-wide effect. In addition, a total of 101 miRNAs show differential expression between healthy tissue and TGCT samples (p<0.1 when adjusting for multiple testing with the Benjamini-Hochberg procedure). Twenty miRNAs have p<1×10-6, including miRNAs previously implicated in TGCT development and in cisplatin sensitivity. Furthermore, clustering demonstrates unique miRNA expression in different TGCT histological subtypes. These results indicate that small RNAs could be used as TGCT markers and potentially be a powerful tool in aiding diagnosis and identification of histological subtypes in TGCT patients, as well as in development of new therapeutic interventions.

Citation Format: Trine Ballestad Rounge, Kari Furu, Rolf Inge Skotheim, Espen Enerly, Trine Berit Haugen, Tom Grotmol. Genome-wide changes in expression of small RNAs in human testis cancer tissue. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A01.
Abstract A47: Meta-analysis of MTHFR polymorphisms in lung cancer: Population health and mutations in the world
Authors: Chen Hsiao-Ling , Shiao Shyang-Yun Pamela K. , Chiang Linda H. , Kusuma Joyce
Published: October 2015

Purpose: The purpose of this meta-analysis is to identify the associations of methylene-tetra- hydrofolate reductase (MTHFR) gene mutations and smoking as risk factors for lung cancer (LC). LC is the leading cause of cancer-related death worldwide. To-date, population health in relations to the epigenetics pathways is not clearly understood. Inconsistent findings have been cumulated to-date on the case control studies of MTHFR gene mutations in LC around the world.

Procedure: On-line databases were searched from PubMed (PM) and PM Central databases for meta-analyses by using a combination of key words including LC, MTHFR, and case control studies. Additional studies were located by cross reference method from located studies. For this analysis, 22 studies published within the last 17 years were identified, containing both control and LC cases of human samples. These papers were reviewed and evaluated using the criteria for the quality of studies by two raters. Relative risks (RR) were calculated for increased or decreased risks for LC.

New Data Findings: Preliminary analyses included 11799 cases and 12322 controls associating MTHFR677 locus and LC in 22 studies; 6916 cases and 8526 controls for MTHFR1298 locus in 14 studies. MTHFR677 TT variant as homozygous mutation type was associated with increased LC risk for all race groups combined (pooled RR = 1.151, 95% CI = 1.045 - 1.267, p = 0.004); and also significant for subgroups of Asians (14 studies, RR = 1.080, 1.007 - 1.158, p = 0.031) and Caucasians (8 studies, RR = 1.334, 1.017-1.749, p = 0.037). Asians combined had greater mutation rates on MTHFR677 TT and TC (TT+TC=19.6+47.2=66.8% for cases and 17.8+47.3=65.1% for controls) than Caucasians (11.4+43.4=54.8% for cases and 9.2+41.9%=51.1% for controls). For association of smoking and LC risk, pooled results from 12639 cases and 11828 controls in 17 studies associating MTHFR gene and LC indicated that smoking increased LC risk (pooled RR=1.116, 1.072 - 1.162, P < 0.001).

Conclusion: Meta-analyses of epigenetic risk factors associating gene mutations and health behaviors can provide useful insights to improve the quality of future cancer prevention and intervention studies. Further studies are needed to document population-based gene mutations in relation to epigenetics pathways for cancer prevention.

Citation Format: Hsiao-Ling Chen, Shyang-Yun Pamela K. Shiao, Linda H. Chiang, Joyce Kusuma. Meta-analysis of MTHFR polymorphisms in lung cancer: Population health and mutations in the world. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A47.
Abstract B02: Head and neck and esophageal cancers after liver transplant: Results from a multicenter cohort study. Italy, 1997-2010
Authors: Serraino Diego
Published: October 2015

Recipients of liver transplant (LT), particularly those with alcohol liver diseases (ALD), are at high risk for cancers. This study quantified the risk of head and neck (HN) and esophageal cancers in 2770 LT recipients transplanted in nine Italian centers during 1990-2010. The number of observed cancer cases in LT recipients was compared to the expected one to obtain standardized incidence ratios (SIRs) and 95% confidence intervals (CI). ALD was documented in 26.9% of the 2770 LT recipients, and 186 post-transplant cancers were diagnosed -including 33 cases of HN cancers (6 cases of tongue carcinoma; 10 cases of other carcinomas of the oral cavity; and 17 cases of larynx carcinoma) and nine cases of esophageal carcinoma. The 10-year cumulative risk for HN and esophageal carcinoma was 2.59%. Overall, HN cancers were nearly 5-fold more frequent in LT recipients than expected (SIR=4.8, 95% CI:3.3-6.8), while esophageal carcinoma was 9-fold more frequent than expected (SIR=9.1, 95% CI: 4.1-17.2). The magnitude of the risks of HN and esophageal carcinomas strongly differed according to the presence of ALD. SIRs ranged from 11.4 in LT with ALD to 2.2 for LT without ALD for all types of HN cancers, and from 23.9 to 2.9, respectively, for esophageal carcinoma. Particularly elevated SIRs in LT with ALD were noted for carcinomas of tongue (23.1, 95% CI:7.5-54.0) or larynx (12.7, 95% CI:6.3-49.2). Our findings confirmed and quantified the large cancer excess risk in LT recipients with ALD. The risk magnitude and the prevalence of ALD herein documented stress the need of timely and specifically tailored programs for the prevention and early diagnosis of cancer among LT recipients.

Citation Format: Diego Serraino. Head and neck and esophageal cancers after liver transplant: Results from a multicenter cohort study. Italy, 1997-2010. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B02.
Abstract B20: The cholesterol metabolite, 27-hydroxycholesterol induces hyperplasia in an androgen receptor-dependent manner in normal prostate RWPE-1 cells
Authors: Raza Shaneabbas , Meyer Megan , Guo Bin , Hammer Kimberly , Ghribi Othman
Published: October 2015

For every 6 men, 1 will be diagnosed with prostate cancer (PCa). Moreover, benign prostatic hyperplasia (BPH) also occurs in 50% of men over the age of 50. Although Androgens are known to play an important role in PCa and BPH, some evidence shows estrogens may be involved as well. Recently a cholesterol oxidized metabolite (oxysterol), 27- hydroxycholesterol (27-OHC) was found to bind to estrogen receptor(ER) and act as a selective ER modulator (SERM). 27-OHC is the most prevalent cholesterol metabolite present in the blood with levels increasing with oxidative stress and age, especially in men. The role of 27-OHC in PCa and BPH remains to be investigated. We propose that 27-OHC has deleterious effect in PCa and BPH, whereas the effect on BPH may be androgen dependent. We recently found that incubation with 27-OHC of RWPE-1 (normal epithelial) and LNCaP (cancer cells) increased cell proliferation in both cell lines. Interestingly, upon incubation of RWPE-1 and LNCaP with 27-OHC, we observed an increase in androgen receptor (AR) activity in RWPE-1, not in LNCaP. Furthermore, we found an increase in AR binding to the Androgen Response Element upon exposure of RWPE-1 to 27-OHC. We also found that upon silencing AR gene expression, 27-OHC-induced proliferation in RWPE-1 was markedly attenuated. Additionally, 27-OHC also diminished Docetaxel-mediated apoptosis in RWPE-1. Altogether, our results propose dysregulated levels of 27-OHC as a new risk factor for BPH and PCa. This indicates a novel role for 27-OHC in the etiopathogenesis of BPH and PCa.

Citation Format: Shaneabbas Raza, Megan Meyer, Bin Guo, Kimberly Hammer, Othman Ghribi. The cholesterol metabolite, 27-hydroxycholesterol induces hyperplasia in an androgen receptor-dependent manner in normal prostate RWPE-1 cells. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B20.
Abstract B39: Aspirin modifies immune cell infiltration of the colonic mucosa in Lynch syndrome: a possible mechanism for cancer prevention
Authors: Hartog Benjamin Lee , Coaker Julie , Bishop Timothy , Mathers John , Doeberitz Magnus von Knebel , Burn John , Kloor Matthias
Published: October 2015

The CAPP2 study showed that 600mg aspirin daily reduced the risk of colorectal cancer (CRC) in Lynch Syndrome (LS) patients. The mechanism by which this occurs is unknown. LS cancers are particularly immunogenic. Aspirin may reduce the risk of cancer in LS patients by altering the immune milieu of the colonic mucosa. We aimed to determine the density of Foxp3-positive T regulatory cells (Treg) or CD3-positive T-cells in the normal colonic mucosa of LS patients enrolled in the CAPP2 study. We then aimed to assess any links between this, aspirin use and tumour development. Serial sections (pre- and post-intervention) from normal colonic biopsies of LS patients treated with 600mg aspirin daily or placebo were immunohistochemically stained for Foxp3 and CD3. Half of the patients chosen in each treatment group developed cancer. The level of infiltration was determined by manually counting stained cells. Aspirin use increased the mean number of infiltrating Tregs from the pre- to the post-intervention biopsy (mean increase +5.33 Tregs/mm2, p=0.048) and this increase was significantly larger in the aspirin group than in the placebo group (aspirin +5.33 Tregs/mm2 v placebo -2.19 Tregs/mm2; p=0.01). There was a greater diversity of Treg counts in patients treated with aspirin compared to placebo. Total T-cell density appeared to be unaffected by aspirin. Aspirin may alter the risk of CRC development in LS patients by changing the immune infiltrate of the colon. Our results provide first evidence that aspirin influences the levels of infiltrating immune cells in the colonic mucosa of LS patients.

Citation Format: Benjamin Lee Hartog, Julie Coaker, Timothy Bishop, John Mathers, Magnus von Knebel Doeberitz, John Burn, Matthias Kloor. Aspirin modifies immune cell infiltration of the colonic mucosa in Lynch syndrome: a possible mechanism for cancer prevention. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B39.
Abstract B50: Differential influence of vitamin D on the tumor promoting eicosanoid PGE2 in women at increased breast cancer risk
Authors: Qin Wenyi , Walker Charles , Sauter Edward
Published: October 2015

Numerous lines of evidence point to the tumor promoting properties of prostaglandin (PG)E2. Preclinical studies have demonstrated the ability of both vitamin D (vitD) and celecoxib to downregulate the eicosanoid. We previously reported that vitD, but not the combination, significantly downregulated PGE2 in normal risk women. We hypothesized that there would be a similar or greater benefit of vitD alone, or in combination with celecoxib, in women at increased breast cancer risk. 40 women at increased breast cancer risk were prospectively enrolled and randomized in double blind fashion for one month (postmenopausal) or one menstrual cycle (premenopausal) to one of four daily treatment regimens: placebo, 400 IU vitD, 2000 IU vitD, or 2000 IU vitD + 400 mg celecoxib. Breast nipple aspirate fluid (NAF) and serum were collected. Both breast specific and systemic levels of PGE2 were measured. There was a significant increase (p=.02) in circulating levels of vitD after treatment in women receiving 2000 IU vitD with or without celecoxib, but not in women receiving placebo or 400 IU vitD. Celecoxib levels increased in those treated with celecoxib but not in the other groups. In the breast, as reflected in NAF, there was a 20% increase (p=.07) in PGE2 after treatment with 2000 IU vitD, with little change after treatment in the other groups. No treatment significantly changed circulating levels of PGE2. These findings suggest that, unlike in normal risk women, 2000 IU vitD may increase levels of a key cancer promoting enzyme in women of increased breast cancer risk. Supported in part with funds from the Komen Foundation and the Department of Defense.

Citation Format: Wenyi Qin, Charles Walker, Edward Sauter. Differential influence of vitamin D on the tumor promoting eicosanoid PGE2 in women at increased breast cancer risk. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B50.
Abstract CN02-01: Is it too late or too little? Prevention through physical activity
Authors: Wolin Kate Y.
Published: October 2015

Physical activity is one of the leading ways to prevent cancer with estimates concluding 30% of cancers in the US could be improved through improvements to diet, obesity and exercise behaviors. Despite the cancer and other chronic disease benefits from physical activity, the majority of the US population remains inactive. Efforts to implement cancer prevention through physical activity are met with questions about the specifics of the relation between physical activity and cancer: Everyone? How much? How hard?

Evidence is accumulating that physical activity across the lifecourse is important for cancer prevention. In addition to reducing risk of colon cancer by more than 20%, physical activity also reduces risk of colon polyps. Lifetime physical activity levels are consistently related to several cancers. Adolescent physical activity is associated with a reduced risk of colon cancer. This epidemiologic evidence has important policy implications as school physical education classes and class time are being reduced.

Research has also suggested that physical activity may have less effect on cancer risk among population subgroups including obese individuals for some cancers.

While the physical activity guidelines recommend 30 minutes of moderate activity each day, they also suggest more is better. However, health promotion and behavioral science research has had only modest success at achieving sustained physical activity levels through intervention. We will review data on whether some benefit can be achieved at lower levels or how much greater the risk reduction may be at higher levels.

This is particularly important in light of research indicating that sedentary time is, independent of physical activity level, associated with an elevated risk of several cancers. Together, this data has pushed prevention messaging in the direction of “do something” instead of “do more.” While the risks of sedentary behavior are important, such messages may detract from research suggesting that for some cancers, such as prostate, participation in vigorous physical activity may be necessary to see a reduction in risk.

The benefits of physical activity for cancer prevention are well known. However, the message may need more refinement in light of emerging evidence on the timing, intensity and duration of activity necessary to reduce risk of specific cancers.

Citation Format: Kate Y. Wolin. Is it too late or too little? Prevention through physical activity. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr CN02-01.
Abstract CN12-02: Dietary HDAC inhibitors: Prevention or therapy?
Authors: Dashwood Roderick H.
Published: October 2015

Lysine deacetylase inhibitors, which include inhibitors of histone deacetylase (HDAC) enzymes, are undergoing clinical trials as anticancer agents. Some exhibit resistance mechanisms linked to anti-apoptotic Bcl-2 functions, such as BH3-only protein silencing. HDAC inhibitors that reactivate BH3-only family members might offer an improved therapeutic approach. We show here that a novel seleno-α-keto metabolite of the dietary compound methylselenocysteine triggers global histone acetylation in human colon cancer cells and activates apoptosis in a p21-independent manner. Profiling of multiple survival factors identified a critical role for the BH3-only member Bcl-2 modifying factor (Bmf). On the corresponding BMF gene promoter, loss of HDAC8 was associated with STAT3/Sp3 transcription factor exchange and recruitment of p300. Treatment with a p300 inhibitor, or transient overexpression of exogenous HDAC8 interfered with BMF induction, whereas RNAi-mediated silencing of STAT3 activated the target gene. This is the first study to identify a direct target gene of HDAC8 repression, namely BMF. Interestingly, the repressive role of HDAC8 could be uncoupled from HDAC1 to trigger Bmf-mediated apoptosis. These findings have implications for the development of HDAC8-selective inhibitors and their roles as chemopreventive vs. therapeutic agents. Supported by NIH P01 grant CA090890.

Citation Format: Roderick H. Dashwood. Dietary HDAC inhibitors: Prevention or therapy? [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr CN12-02.
Abstract PL01-02: Influence of the microbiota on cellular proliferation and survival
Authors: Neish Andrew Scott
Published: October 2015

The resident prokaryotic microbiota of the mammalian intestine influences diverse homeostatic functions of the gut, including maintenance of barrier function, modulation of immune responses, as well as energy and nutrient extraction. Additionally, through studies of germ free mice, it has become apparent that commensal prokaryotic organisms are involved in the regulation of growth and survival in the intestinal epithelia, and thus may play fundamental roles in the pathogenesis of colon cancers. However, the molecular mechanisms of growth control by prokaryotes in the gut are largely unknown. It is increasingly recognized that physiologically generated reactive oxygen species (ROS) function as signaling secondary messengers that influence cellular proliferation and differentiation in a variety of biological systems. We have shown that commensal bacteria, particularly members of the genus Lactobacillus, can activate NADPH oxidase 1 (Nox1)-dependent ROS generation and modulate multiple cellular pathways, including NF-kB, ERK-MAPK and focal adhesion kinase, that are involved in control of epithelial cellular survival, proliferation, and migration. ROS inducing commensal bacteria can rapidly stimulate consequent cellular proliferation in intestinal stem cells upon initial ingestion into the murine or Drosophila intestine, illustrating the highly conserved nature of this host microbe interaction. Additionally, a well-studied and evolutionarily highly conserved system for transducing exogenous stimuli into eukaryotic host tissues is Nrf2 signaling. Nrf2 pathway activation upregulates a regulon of genes including those involved in xenobiotic and ROS detoxification, as well as pro-restitutive function. This pathway has attracted considerable attention because small molecule inducers of Nrf2 have cytoprotective and growth modulatory effects. We show cellular ROS generated in response to contact with lactobacilli have cytoprotective effects in the intestinal epithelium through the activation of Nrf2 responsive cytoprotective genes. These data suggest that the Nrf2 pathway, and perhaps other highly conserved pathways that respond to environmental alterations, have been adapted as signaling conduits between eukaryotic host and prokaryotic symbiont, and highlight the role the microbiota plays in eukaryotic cytoprotective pathways. Characterization of these pathways may have significant implications in the delineation of a eubiotic microbiota, and in the identification of probiotic microbes with potential to influence epithelial growth and survival.

Citation Format: Andrew Scott Neish. Influence of the microbiota on cellular proliferation and survival. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr PL01-02.
Abstract PL02-01: Nutrition, epigenetics, and cancer
Authors: Waterland Robert A.
Published: October 2015

Transient nutritional exposures during critical ontogenic periods can cause persistent changes in gene expression, metabolism, and risk of various diseases including cancer. We have been investigating whether such ‘developmental programming’ occurs via nutritional influences on developmental epigenetics. Our studies in agouti viable yellow and axin fused mice showed that developmental establishment of DNA methylation at ‘metastable epialleles’ is especially sensitive to maternal nutritional status around the time of conception. Lately, using a multiple-tissue screen for interindividual variation in DNA methylation, we have identified human genomic regions that appear to be metastable epialleles. Stochastic establishment of DNA methylation at these loci is affected by maternal nutrition around the time of conception, consistent across multiple tissues, and stable for many years. Most recently, our studies using genome-wide bisulfite sequencing have identified candidate metastable epialleles that are associated with genes implicated in human cancer, potentially providing opportunities for cancer risk assessment and prevention.

Citation Format: Robert A. Waterland. Nutrition, epigenetics, and cancer. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr PL02-01.