bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1923: Distinct evolutionary and mutational patterns in oncogenes and tumor suppressor genes
Authors: Liu Li , Chang Yung , Ye Jieping , Kumar Sudhir
Published: August 2015

Oncogenes and tumor suppressor genes play different roles in carcinogenesis and tumor progression. However, very little attention has been paid to compare their mutational and evolutionary patterns. As such, these two groups of genes are often mingled together in computational modeling and analysis. To bridge this gap, we examined the evolutionary profiles of 150 oncogenes and 102 tumor suppressor genes and their somatic mutations recorded in the COSMIC database. We found that these two groups of genes display distinct evolutionary and mutational patterns. In general, oncogenes are more conserved than tumor suppressor genes, as revealed by multiple-species comparisons. The stronger purifying selection on oncogenes is also reflected at positions harboring somatic missense mutations. Thus, somatic mutations disrupting oncogenes tend to have higher functional impact than those disrupting tumor suppressor genes. However, the mutational landscape of oncogenes is often dominated by one or very few hotspots, while multiple hotspots and frequent sporadic mutations are found in tumor suppressor genes. Furthermore, CpG hypermutations contribute to 58% of highly recurrent mutations in tumor suppressor genes, but only 4% to those in oncogenes. These patterns indicate that most random somatic mutations in oncogenes are also under stronger purifying selection as compared to those in tumor suppressor genes. However, once an advantageous mutation in an oncogene arises, it tends to increase the fitness significantly such that a hard sweep pursues, which eventually reduces the mutational diversity of the tumor. On the contrary, the relatively mild selection on tumor suppressor genes allows more neutral mutations to accumulate. When eventually the deactivation of both copies of a tumor suppressor gene triggers positive selection, the mutational diversity of the tumor has increased significantly. These distinct evolutionary and mutational patterns warrant independent modeling of oncogenes and tumor suppressor genes in studies that incorporate these features in the analysis, such as prediction of driver mutations or inference of evolutionary paths for cancers.

Citation Format: Li Liu, Yung Chang, Jieping Ye, Sudhir Kumar. Distinct evolutionary and mutational patterns in oncogenes and tumor suppressor genes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1923. doi:10.1158/1538-7445.AM2015-1923
Abstract 1931: Mathematical modeling predicts exponential growth kinetics for metastases in the lymphatic vessels in the absence of vascularization
Authors: Griswold Ruth E. , Podgrabinska Simona , Das Suvendu , Griffith Boyce , Peskin Charles S. , Skobe Mihaela
Published: August 2015

The objective of this study was to examine how the biophysical characteristics of different metastatic niches influence survival and growth of metastatic cells using mathematical modeling. In the lung, metastases can form in the lung parenchyma or in the lymphatic vessels. The presence of cancer metastases in the lung lymphatics is associated with rapid disease progression and extremely poor prognosis for patients. Remarkably, metastases in pulmonary lymphatics are avascular, yet grow larger than metastases in the lung parenchyma. To explain rapid growth of metastases in the lymphatics in the absence of angiogenesis, we have developed a 3D mathematical model of intralymphatic tumor growth. This is a deterministic continuum model based on partial differential equations used to describe avascular tumor growth and adapted to reflect the unique architecture of the lymphatic vasculature. Our model predicts that the cylindrical shape of the lymphatic vessel, which constrains growth of the tumor in two dimensions yet allows indefinite growth along the vessel, enables oxygen levels to remain high throughout the tumor. The greater diffusion coefficient of oxygen in lymph further improves oxygenation of intralymphatic metastases, which rarely become hypoxic. Improved tumor oxygenation leads to decreased tumor cell death and a rapid increase of metastatic burden in the lymphatics. Importantly, our model predicts that the kinetics of growth of intralymphatic metastases is exponential. This contrasts the established view that all tumors follow Gompertzian growth kinetics, i.e., that tumor growth rate decreases as tumor size increases. Furthermore, these findings indicate that the lymphatic niche is a favorable environment for metastatic growth, and that angiogenesis is not always required for the progressive growth of metastases. Finally, our predictions of different growth kinetics of primary tumors and their metastases suggest that the treatment schedules for metastatic disease could be further optimized to achieve better efficacy.

Citation Format: Ruth E. Griswold, Simona Podgrabinska, Suvendu Das, Boyce Griffith, Charles S. Peskin, Mihaela Skobe. Mathematical modeling predicts exponential growth kinetics for metastases in the lymphatic vessels in the absence of vascularization. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1931. doi:10.1158/1538-7445.AM2015-1931
Abstract 1939: Discovery and proteogenomic investigation of genetic variants in human cancers
Authors: Huang Kuan-lin , Wang Jaiyin , Cao Song , Xie Mingchao , Jayasinghe Reyka , Ning Jie , McLellan Michael , Wendl Michael , Scott Adam , Johnson Kimberly , Davies Sherri , Fenyö David , Townsend Reid , Chen Feng , Parvin Jeffrey , Ellis Matthew , Ding Li
Published: August 2015

A significant fraction of cancers have a heritable component, and require an interplay between somatic and germline variants. Common and rare germline variants have been investigated by previous GWAS and family based studies. However, a comprehensive analysis of both somatic and germline variants in cancer using high throughput sequencing data to discover genetic variants of functional relevance is lacking. Herein, we investigated the potential role of somatic and germline variants from over 20 major cancer types from large-scale studies such as TCGA and ICGC and discovered thousands of somatic and germline variants in cancer genomes. To link these genetic variants to cancer phenotypes, we analyzed the proteomics data in breast, ovarian and colorectal cancers generated by the Clinical Proteomic Tumour Analysis Consortium (CPTAC) using a PepScan pipeline that can detect whether a genomic variant is observed at the peptide level. The pipeline incorporated QUILTS to construct patient-specific protein database and MS-GF+ to identify peptide sequences in the database from MS spectra. Our analysis validated roughly 2% of non-synonymous genetic variants in peptides with matched spectra. We correlated the effect of genetic mutations on proteomic subtypes based on global protein expression levels. Additionally, we assessed the role of genetic variations in kinase genes using phosphoproteome profiles, and identified downstream markers that may be candidate targets for diagnosis or treatment. This analysis also helped us prioritize kinase variants that are likely functional candidates for experimental validation. In conclusion, the comprehensive study of genetic variants utilizing an integrated proteogenomic approach revealed genetic variants with potential functional impacts in cancer.

Citation Format: Kuan-lin Huang, Jaiyin Wang, Song Cao, Mingchao Xie, Reyka Jayasinghe, Jie Ning, Michael McLellan, Michael Wendl, Adam Scott, Kimberly Johnson, Sherri Davies, David Fenyö, Reid Townsend, Feng Chen, Jeffrey Parvin, Matthew Ellis, Li Ding. Discovery and proteogenomic investigation of genetic variants in human cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1939. doi:10.1158/1538-7445.AM2015-1939
Abstract 194: Deregulation of miR-222-ABCG2 regulatory module in tongue squamous cell carcinoma contributes to chemoresistance and enhanced metastatic potential
Authors: Wang Anxun , Zhao Luodan , He Qianting , Zhao Tingting , Wang Wei , Zhou Xiaofeng
Published: August 2015

Chemoresistance often associated with other clinical characteristics, such as enhanced metastatic potential. However, the underlying molecular mechanism remains unclear. Our previous studies had revealed that microRNA-222 (miR-222) regulates the cell invasion [Cancer Genomics Proteomics 2009 6:131-138], and plays a role in cell proliferation in tongue squamous cell carcinoma (TSCC) [FEBS Lett. 2010 584(18):4115-20]. The aim of this study is to elucidate the role of miR-222-ABCG2 pathway in the association of cisplatin (cDDP) resistance with enhanced cell migration and invasion ability in TSCC. First, we confirmed the association between cDDP resistance (measured by IC50) and metastatic potential (assessed by migration and invasion assays) using TSCC cell lines and primary cultures from TSCC cases. The siRNA-mediated ABCG2 knockdown led to enhanced cDDP responsiveness, and reduced metastatic potential in TSCC cells. On the contrary, ABCG2 overexpression induced cDDP resistance, and enhanced cell migration and invasion in TSCC cells. Bioinformatics analysis revealed that ABCG2 is a target gene of miR-222, and the direct interaction of miR-222 with ABCG2 mRNA was confirmed by luciferase reporter gene assay. Functional analyses indicated that miR-222 downregulated the expression of ABCG2 gene and enhanced cDDP responsiveness, as well as reduced cell migration and invasion in TSCC cells. Thus, our results confirmed the association between cDDP resistance and enhanced metastatic potential in TSCC. ABCG2 is a direct target gene of miR-222, and deregulation of miR-222-ABCG2 regulatory module in TSCC contributes to both cDDP resistance and enhanced metastatic potential.

Citation Format: Anxun Wang, Luodan Zhao, Qianting He, Tingting Zhao, Wei Wang, Xiaofeng Zhou. Deregulation of miR-222-ABCG2 regulatory module in tongue squamous cell carcinoma contributes to chemoresistance and enhanced metastatic potential. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 194. doi:10.1158/1538-7445.AM2015-194
Abstract 1945: Self-phosphorylation primes JNK2 for activation by MKK4 in glioblastoma and non-small cell lung carcinoma
Authors: Kaoud Tamer S. , Dalby Kevin N.
Published: August 2015

JNKs (c-Jun N-terminal kinases) are members of the mitogen-activated protein kinase (MAPK) family, known primarily for their response to cell stress. JNK activation is mediated cooperatively by both MKK4 and MKK7. Uniquely, c-Jun N-terminal kinase 2 (JNK2) isoform has been reported to be constitutively activated (without MKK4/7). Recent studies in glioblastoma and lung carcinoma have identified important roles for JNK2 constitutive activation (but not JNK1). Using phospho-specific antibodies, recombinant activated (MKK4 & MKK7), inactivated (JNK1 & JNK2) and phos-tag PAGE, we have identified that JNK2 self-phosphorylation results in the production of active JNK2 (phosphorylated on both Thr-183 and Tyr-185) and a form of mono-phosphorylated JNK2 (phosphorylated only on Thr-183) whose activation is MKK4-dependent (phosphorylates Tyr-185), but MKK7-independent. The effect of MKK4 on JNK2 constitutive activation has been further investigated in mouse embryonic stem cells that have MKK4 and/or MKK7 knocked out. MKK4 but not MKK7 existence in these cell lines enhanced JNK2 autoactivation. Interestingly, knockdown of MKK4 or JNK2 in U78MG glioblastoma cell line, A549 non-small cell lung carcinoma cell line and HEK293 cells dramatically decreased JNK2 constitutive activation and inhibited A549 cellular growth and anchorage-independent growth that have been reported to be regulated by JNK2 constitutive activity. As a conclusion, our data demonstrates for the first time that JNK2 autophosphorylation primes its activation by MKK4. This phenomenon can allow JNK2 activity to be further regulated by discrete cellular signals.

Citation Format: Tamer S. Kaoud, Kevin N. Dalby. Self-phosphorylation primes JNK2 for activation by MKK4 in glioblastoma and non-small cell lung carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1945. doi:10.1158/1538-7445.AM2015-1945
Abstract 1949: Oncogenic signaling in amphiregulin- and EGFR-expressing PTEN-null human breast cancer
Authors: Kappler Christiana S. , Guest Stephen T. , Smith Ericka L. , Irish Jonathan C. , Garrett-Mayer Elizabeth , Kratche Zachary , Ethier Stephen
Published: August 2015

A subset of triple negative breast cancer (TNBC) is characterized by overexpression of the epidermal growth factor receptor (EGFR) and loss of PTEN, and patients with these factors have a poor prognosis. In addition, approximately half of all basal breast cancers show autocrine activation of EGFR by amphiregulin (AREG), resulting in altered receptor trafficking and downstream signaling. However, despite the strong rationale for targeting EGFR in the treatment of TNBC, EGFR inhibitors have performed poorly in clinical trials. To further analyze the signaling processes active in this subset of TNBC, we performed reverse-phase protein array (RPPA) analysis on SUM149 cells, a highly tumorigenic and metastatic PTEN-null cell line that expresses high levels of AREG and EGFR, and MCF10A cells, a non-transformed mammary epithelial cell line cultured in the presence of either EGF or AREG. This analysis identified a number of signaling components mediated specifically by amphiregulin, including marked changes in integrin expression and increased levels of fibronectin, which is known to be a mediator of invasive capacity via interaction with integrin β1. RPPA analysis also revealed elevated AKT activity in SUM-149 cells, which was not surprising given the lack of PTEN expression. Interestingly, this AKT activity is not abrogated by treatment with the EGFR inhibitor gefitinib, nor by treatment with PI3K inhibitors. These findings and the results of preliminary experiments in SUM149 cells re-expressing PTEN suggest that AKT activity in these cells is, at least partly, independent of EGFR and PI3K activity. In addition, expression profiling demonstrated that AREG-activated EGFR regulates gene expression differently than EGF-activated EGFR, and functional analysis via genome-scale shRNA screening identified a set of genes, including PLK1 and BIRC5, that are regulated by EGFR in MCF10A cells but uncoupled from EGFR signaling in SUM149 cells, although they are essential for the survival of SUM-149 cells. Thus, our results demonstrate that in cells with constitutive EGFR activation and PTEN loss, critical survival genes are uncoupled from regulation by EGFR, a mechanism that is likely to mediate resistance to EGFR inhibitors.

Citation Format: Christiana S. Kappler, Stephen T. Guest, Ericka L. Smith, Jonathan C. Irish, Elizabeth Garrett-Mayer, Zachary Kratche, Stephen Ethier. Oncogenic signaling in amphiregulin- and EGFR-expressing PTEN-null human breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1949. doi:10.1158/1538-7445.AM2015-1949
Abstract 1955: IKKϵ maintains MEK activation and suppresses non-canonical NF-κB signaling in triple-negative breast cancer
Authors: House Carrie , Grajales Valentina , Wubneh Helmae , Kimble Danielle , Kim Marianne , Annunziata Christina
Published: August 2015

Metastatic breast cancer carries a poor prognosis despite the success of newly targeted therapies. Treatment options remain especially limited for the subtype of triple negative breast cancer (TNBC). Several signaling pathways, including NF-κB, are altered in TNBC, and the complexity of this disease implies multifaceted pathway interactions and compensatory signaling. We hypothesized that a subset of TNBCs expresses IKKϵ to promote a specific NF-κB signaling program that can enhance metastatic potential. Our data suggest that IKKϵ supports MEK activation and suppresses non-canonical signaling by the p52 NF-κB transcription factor. We found that NF-κB p52 expression is inversely proportional to activated MEK. We further demonstrate that IKKϵ and MEK cooperate to support viability and invasion potential under adherent conditions, whereas the p52 transcription factor supports viability under non-adherent conditions, underscoring the contrasting roles of these proteins. This study illustrates the diverse roles of NF-κB signaling components in TNBC, and highlights the adaptability of NF-κB in maintaining cancer cell survival under different microenvironments. A better understanding of the diversity of NF-κB signaling may ultimately improve the development of novel therapeutic regimens for TNBC.

Citation Format: Carrie House, Valentina Grajales, Helmae Wubneh, Danielle Kimble, Marianne Kim, Christina Annunziata. IKKϵ maintains MEK activation and suppresses non-canonical NF-κB signaling in triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1955. doi:10.1158/1538-7445.AM2015-1955
Abstract 1957: Negative regulation of Sox9 by glycogen synthase kinase 3 beta phosphorylation and SCFFbw7-dependent ubiquitination in cancer
Authors: Hong Xuehui , Liu Wenyu , Inuzuka Hiroyuki , Liu Lianxin , Pine Sharon R.
Published: August 2015

Sox9 is a member of the SOX [Sry-related high-mobility group (HMG) box] family of transcription factors, with known functions in proliferation, epithelial-mesenchymal transition (EMT), stem cell maintenance and senescence. Sox9 protein levels are elevated in several different cancer types, including lung cancer and osteosarcoma. Furthermore, Sox9 overexpression is associated with poor survival in both cancer types. We recently reported that Sox9 is a direct transcriptional target of the Notch signaling pathway and mediates Notch1-induced EMT in lung cancer (Capaccione et al., Oncotarget, 2014). Fbxw7 (F-box and WD repeat domain-containing 7) is a member of the SCFFbw7E3 ubiquitin ligase complexthat targets several oncogenic proteins for degradation, including Notch1. We hypothesized that Sox9 is targeted for degradation by SCFFbw7. Knocking down or overexpressingFbxw7 significantly increasedor decreased, respectively, endogenous Sox9 protein levels in lung cancer and osteosarcoma cell lines. In addition, overexpression of Fbxw7 resulted in active degradation of ectopic Sox9 protein levels, when assessed in combination with cycloheximide, and did so in a dose dependent-manner.Furthermore, both Sox9 and FBXW7 were detected in immunoblots after the reciprocal protein was immunoprecipitated. Because substrate degradation by SCFFbw7 is typically phosphorylation-dependent, frequently by glycogen synthase kinase (GSK)3-beta, we examined whether modulation of GSK3-beta could affect FBXW7-induced Sox9 degradation. Treatment of cells with the GSK3-beta inhibitor, CHIR99021, completely abolished Sox9 degradation by ectopically overexpressed FBXW7, in a dose-dependent manner. We next identified four putative phosphorylation sites within potential FBXW7 degron motifs in Sox9.Mass spectrophotometric analysis confirmed these sites within Sox9 are indeed phosphorylated.In summary, we found that the E3 ubiquitin ligase complex (SCFFbw7) targets Sox9 for ubiquitin-mediated degradation in a GSK3-beta-mediated Sox9 phosphorylation-dependent manner. As a result, this negative regulation of Sox9 by GSK3-beta/FBXW7 could lead to inhibition of Sox9-mediated proliferation, EMT and stemness. This new regulatory mechanism of Sox9 could have diagnostic and therapeutic implications for lung cancer, osteosarcoma, as well as other cancers.

Citation Format: Xuehui Hong, Wenyu Liu, Hiroyuki Inuzuka, Lianxin Liu, Sharon R. Pine. Negative regulation of Sox9 by glycogen synthase kinase 3 beta phosphorylation and SCFFbw7-dependent ubiquitination in cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1957. doi:10.1158/1538-7445.AM2015-1957
Abstract 1969: Regulation of cell cycle progression in BRAFV600E inhibitor-resistant human melanoma by histone deacetylase inhibitor
Authors: Toresss-Collado Antoni X. , Nazarian Ramin , Jazirehi Ali R.
Published: August 2015

The BRAFV600E specific inhibitor vemurafenib blocks MAPK pathway and induces cell cycle arrest at the G0/G1 phase leading to apoptosis of melanomas. To gain an understanding of the dynamics of cell cycle regulation during vemurafenib therapy, we established several vemurafenib-resistant (VemR) human melanoma sublines from BRAFV600E vemurafenib-sensitive parental lines. Vemurafenib provoked G0/G1 phase arrest in parental but not in VemR sublines. We hypothesized that the refractoriness of VemR sublines to vemurafenib-mediated cell cycle inhibition can be partially rescued by the chromatin modifier SAHA. SAHA promoted G2/M arrest at expense of the S phase irrespective of vemurafenib sensitivity. In parental lines, combination of SAHA and vemurafenib induced both G0/G1 arrest and apoptosis, whereas in VemR sublines combination induced G0/G1 as well as G2/M arrest resulting in dramatic cytostasis. VemR sublines preferentially exhibited ERK1/2 and AKT hyperphosphorylation. Gene expression profiling revealed MAPK hyperactivation and deregulations of cyclins and cyclin-dependent kinases (CDK) in VemR sublines, all of which were reversed by SAHA; changes that may explain the cytostatic effects of SAHA. These results suggest that unresponsiveness of VemR sublines to the biological effects of vemurafenib may be amenable by SAHA. These in vitro results, while require further investigation may provide rational biological basis for combination therapy in the management of VemR melanoma.

Citation Format: Antoni X. Toresss-Collado, Ramin Nazarian, Ali R. Jazirehi. Regulation of cell cycle progression in BRAFV600E inhibitor-resistant human melanoma by histone deacetylase inhibitor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1969. doi:10.1158/1538-7445.AM2015-1969
Abstract 1978: Relationship between transcription factor TWIST1 and microRNA34a in metastatic cancer cells
Authors: Khan Md. Asaduzzaman , Tania Mousumi , Wei Chunli , Fu Junjiang
Published: August 2015

Background: Micro RNAs (miRNAs) are the important tools in RNA-interference (RNAi) technology, which is comparatively recent but one of the most promising bio-molecular tools for gene regulation. MiRNAs can interfere with certain genes in target specific manner, and they are being extensively investigated for cancer therapeutics. This study investigated the role of miR-34a on the expression of transcription factor TWIST1, which is involved in metastatic carcinomas.

Methods: The expression of miR34a and TWIST1 was measured by quantitative polymerase chain reaction (qPCR) analysis in different cancer cell lines and breast cancer tissues. Then we have transfected the precursor and inhibitor of miR-34a into another TWIST1 rich 4T1 cancer cell, and isolated the total RNA and miRNAs for the analysis of TWIST1 expression, as well as miR-34a.

Results: Initially, we have observed that miR34a is highly expressed in lower invasive MCF7 and T47D cancer cells, whereas its expression in higher invasive MDA-MB-231, MDA-MB-435 and BT-549 cancer cells is low. Oppositely, TWIST1 expression is relatively lower in MCF7 and T47D cells, but higher in MDA-MB-231, MDA-MB-435 and BT-549 cells. This inverse relationship indicated that TWIST1 might be a target of miR-34a. Interestingly transfection of miR34a precursor inhibited TWIST1 expression in 4T1 cancer cells.

Conclusions: This study reports that miR-34a has reverse correlation with the high TWIST1 expression in metastatic breast cancer. Regulation of TWIST1 by miR-34a might be a potential tool in cancer diagnostics and therapeutics, especially for the treatment of metastatic cancers.

Funding support: This work was supported in part by the NSFC (81172049), the Science and Technology Innovation Team of Colleges and Universities of Sichuan Province (13TD0032), the Applied Basic Research Program of Science and Technology Department of Sichuan Province (14JC0797,)and Luzhou City Special Foundation (2013LZLY-J10).Corresponding author email:fujunjiang@hotmail.com

Citation Format: Md. Asaduzzaman Khan, Mousumi Tania, Chunli Wei, Junjiang Fu. Relationship between transcription factor TWIST1 and microRNA34a in metastatic cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1978. doi:10.1158/1538-7445.AM2015-1978
Abstract 1981: Regulation of NF-kB signaling pathway by glucocorticoid in breast cancer cells
Authors: Lopez-Dee Zenaida , Ling Jun
Published: August 2015

Steroid hormone signaling through nuclear receptors plays critical roles in every stage of breast cancer development. Although estrogen receptor (ER) and progesterone receptor (PR) are well studied, due to the high heterogeneity of breast cancer, therapies targeting these nuclear receptors are still not effective enough or generate inconsistent and even controversial results. In this study, we focused on the glucocorticoid (GC)/ glucocorticoid receptor (GR) signaling to investigate how it regulates NFkB activity that leads to differential outcomes in different subtypes of breast cancer. A qRT-PCR array containing a curated NF-kB responsive gene set (84 genes) was utilized in this study to analyze the effect of GC/GR on basal and luminal subtypes of breast cancer cells. It was identified that MDA-MB-231 cells (basal subtype) were more responsive than MCF7 cells (luminal subtype) to GC treatment as the former showed more down- or up-regulated NF-kB target genes. Negative regulation of the NF-kB target genes was more prevalent in both cells, which is consistent with the general rule of trans-repression of NF-kB by GR. However, there were also a number of NF-kB target genes up-regulated by GC in both subtypes of breast cancer cells, suggesting that the trans-activation of NF-kB by GR may also play an important role in breast cancer cell growth and pathological behaviors. Among the differentially expressed genes in both cell types, genes with functions in cell migration and adhesion are highly regulated, such as CXCL1, CCL2, ICAM1, VCAM1, BIRC3 and SNAP25, implying that GC may mainly regulate the invasion and metastasis of breast cancer cells via NF-kB signaling. Biochemical studies identified that GR was activated by GC differently in MDA-MB-231 and MCF7 cells; the interaction between GR and various NF-kB subunits were also different in these cells, thus elucidating part of mechanisms underlying the differential regulation of NF-kB by GC in different subtypes of breast cancer cells.

Citation Format: Zenaida Lopez-Dee, Jun Ling. Regulation of NF-kB signaling pathway by glucocorticoid in breast cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1981. doi:10.1158/1538-7445.AM2015-1981
Abstract 2039: Trim21: A novel regulator of Par-4 and oncogenic signaling
Authors: Nguyen Jeffrey , Irby Rosalyn
Published: August 2015

Prostate apoptosis response protein 4 (Par-4) is a tumor suppressor that induces apoptosis selectively in cancer cells. Although Par-4 levels have been shown to be regulated by ubiqutin-mediated proteolysis, it is not known whether Par-4 function is regulated by ubiquination. To identify novel protein interaction partners of Par-4, we used co-immunoprecipitation of Par-4, followed by in-solution trypsin digestion and mass spectrometry. We demonstrate that Trim21, an E3 ligase that acts as a negative regulator of inflammatory signaling partially through ubiquitination of various downstream transcription factors, is a novel Par-4 interacting protein, and may regulate the activity of Par-4. Furthermore, similar to Par-4, we found that Trim21 inhibits Akt activation. Our studies reveal that Trim21 is a novel E3 ligase of Par-4, and extends its role from regulation of immune signaling to regulation of apoptosis and oncogenic signaling in colon cancer cells.

Citation Format: Jeffrey Nguyen, Rosalyn Irby. Trim21: A novel regulator of Par-4 and oncogenic signaling. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2039. doi:10.1158/1538-7445.AM2015-2039
Abstract 2051: Regulation of RNA processing by PADI4 pathway
Authors: Tanikawa Chizu , Ueda Koji , Nakamura Yusuke , Matsuda Koichi
Published: August 2015

We recently reported that p53 regulated protein citrullination through the transcriptional regulation of PADI4 that converts an arginine residue in proteins to a citrulline residue. In response to DNA damage, p53-PADI4 pathway induced citrullination of NPM1, Histone H4, and Lamin C, and subsequently promoted apoptotic pathway. To elucidate entire roles of p53-PADI4 pathway, we screened novel targets by LC-MS analysis and found that majority of hnRNP family members are citrullinated by ectopic expression of PADI4. LC-MS analysis and specific antibody revealed citrullination of hnRNP G at arginine 223 residue. In addition, citrullination of hnRNP G inhibited interaction with RNA helicases or other hnRNP family members. Citrullination motif analysis revealed the enrichment of D, G, S, E, and A at -1 (56.0%), +1 (55.8%) and +2 (45.8%) position. Since hnRNP family is involved in RNA processing, we conducted RNA sequence analysis by using bone marrow from Padi4+/+ or Padi4-/- mice. As a result, Padi4 was shown to alter the splicing pattern of several genes. Moreover, Padi4-/-p53+/- mice exhibited significantly shorter survival time compared with Padi4+/+p53+/- mice. Our finding revealed a novel role of p53-PADI4 pathway in RNA splicing and human carcinogenesis.

Citation Format: Chizu Tanikawa, Koji Ueda, Yusuke Nakamura, Koichi Matsuda. Regulation of RNA processing by PADI4 pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2051. doi:10.1158/1538-7445.AM2015-2051
Abstract 2057: Protocadherin 10-mediated suppression of tumorigenesis and metastasis in colorectal cancer
Authors: hung yu-lin
Published: August 2015

Colorectal cancer (CRC) is one of the leading types of cancer death worldwide, and over one third of these patients will die of their disease mainly due to distant metastasis. Genomic deletion that occurs at tumor suppressor loci is a common genetic aberration in CRC. By using loss of heterozygosity analysis, we identified Protocadherin 10 (PCDH10) as a novel tumor suppressor gene in CRC. Ectopic expression of PCDH10 reduced cancer cell proliferation, anchorage-independent growth, migration and invasion, as well as increased serum starvation-induced apoptosis in vitro. Subcutaneous injection of PCDH10-expressing CRC cells in SCID mice showed the reduction of tumor growth compared with that observed in mock-inoculated mice. Furthermore, via intrasplenic implantation, the re-expression of PCDH10 in silenced cells restrained liver metastasis and improved survival in SCID mice. The molecular mechanisms of PCDH10-mediated tumor suppression are involved in the up-regulation of p53-p21 pathway and down-regulation of active β-catenin. Taken together, PCDH10 could restrain cell growth and epithelial-to-mesenchymal transition, and thus inhibit the development and progression of CRC.

Keywords:

PCDH10, tumor suppressor gene, colorectal cancer, molecular mechanism

Category : MCB04 Oncogenes and Tumor Suppressor Genes

Citation Format: yu-lin hung. Protocadherin 10-mediated suppression of tumorigenesis and metastasis in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2057. doi:10.1158/1538-7445.AM2015-2057
Abstract 2059: Novel roles for GNA13 and RHOA as tumor suppressor genes
Authors: O'hayre Morgan , Inoue Asuka , Sales Katiuchia , Kufareva Irina , Callejas Valera Juan Luis , Guo Fukun , Mikelis Constantinos , DiPasquale Giovanni , Finkel Kira , Aoki Junken , Zheng Yi , Bugge Thomas H. , Gutkind J. Silvio
Published: August 2015

G-protein coupled receptors (GPCRs) and G-proteins are critical signal transduction molecules that regulate cell survival, proliferation, motility and differentiation. However, mutations and disruptions in the expression or function of these molecules have been linked to growth, progression and metastasis of various cancers. Recently, major efforts in the area of genome-wide sequencing of tumors have unveiled numerous previously uncharacterized mutations in G-proteins and GPCRs, which could have significant implications to cancer initiation and progression. In particular, mutations in the gene encoding the G-protein G13 (GNA13) and/or its downstream effector, RhoA, have been identified in B cell lymphomas (particularly Burkitt's lymphoma and Diffuse Large B cell Lymphoma), T cell lymphomas, and Head and Neck Squamous Cell Carcinomas (HNSCCs). Our analyses indicate that these mutations are highly statistically significant over background cancer gene mutation rate, and mutations in GNA13 alone occur in ∼10-15% of patients with Burkitt's lymphoma and Diffuse Large B cell Lymphoma. Surprisingly, although G13 and RhoA have previously been linked to cellular transformation and metastatic potential of epithelial cancers, our data suggests that the mutations in GNA13 and/or RHOA in these B cell lymphomas and HNSCC are inhibitory in nature. Furthermore, our results indicate a tumor suppressive function for wild-type GNA13 and RHOA in in vivo cancer models. Overall, our data suggest a novel function tumor suppressive function for the G13/RhoA axis in multiple human malignancies.

Citation Format: Morgan O'hayre, Asuka Inoue, Katiuchia Sales, Irina Kufareva, Juan Luis Callejas Valera, Fukun Guo, Constantinos Mikelis, Giovanni DiPasquale, Kira Finkel, Junken Aoki, Yi Zheng, Thomas H. Bugge, J. Silvio Gutkind. Novel roles for GNA13 and RHOA as tumor suppressor genes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2059. doi:10.1158/1538-7445.AM2015-2059
Abstract 2090: GLI3 repressor levels determine Hedgehog pathway activity and predict response to Smoothened antagonist in acute myeloid leukemia
Authors: Chaudhry Parvesh , Singh Mohan , Triche Tim , Jorapur Aparna , Gill Parkash S. , Merchant Akil
Published: August 2015

The Hedgehog (Hh) signaling pathway is activated in most hematological and solid cancers and is a promising target for therapeutic development. Deletions in the receptor Patched (PTCH) or activating mutations in the upstream positive regulator Smoothened (SMO) have been reported in a few cancers such as basal cell carcinoma and medulloblastoma, but are largely absent in most tumor types; therefore, the mechanism of pathway activation in most cancers remains unknown. In normal tissues, Hh pathway activation via PTCH/SMO causes an increase in the downstream activating transcription factor GLI1 and a decrease in the transcriptional repressor GLI3R. We confirm that the Hh pathway is active in acute myeloid leukemia (AML) and is required for cell survival, however, this activity is largely independent of the upstream activator SMO. Using siRNA knock down of GLI1, GLI3 and SMO in AML cell lines, Gli3 conditional knock out mice, and primary AML samples, we are able to show that loss of the GLI3R repressor function is sufficient to activate Hh target gene expression independent of ligand binding, and GLI3R levels correlate inversely with GLI1 levels. Importantly, we show that GLI3R is required for the therapeutic effect of SMO antagonists in AML samples and restoration of GLI3R restores sensitivity to SMO antagonists in AML cell lines. Epigenetic and gene expression analysis of the TCGA AML data set reveals that the GLI3 expression is silenced in most AML patient samples. We demonstrate in vitro and in patients that treatment with hypomethylating agents restores GLI3R levels and sensitivity to SMO antagonists in AML. In a transgenic mouse model of myeloproliferative disease (vav-Jak2V617F, gift of Joe Zhao, OUHSC) effective treatment with SMO antagonists are associated with increases in GLI3R but no changes in GLI1. Finally we show that GLI3R can directly repress expression of AKT and in vivo responses to SMO antagonists are correlated with changes in AKT expression, independent of GLI1 levels. In summary, this study provides the first evidence that GLI3R plays an essential role in SMO independent Hh signaling in AML, and suggests that GLI3R could serve as a potential biomarker for patient selection in SMO antagonist clinical trials. Furthermore, these data provide important mechanistic data to support rational combinations of hypomethylating agents with SMO antagonists in clinical trials.

Citation Format: Parvesh Chaudhry, Mohan Singh, Tim Triche, Aparna Jorapur, Parkash S. Gill, Akil Merchant. GLI3 repressor levels determine Hedgehog pathway activity and predict response to Smoothened antagonist in acute myeloid leukemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2090. doi:10.1158/1538-7445.AM2015-2090
Abstract 2096: High sensitivity of cutaneous T-cell lymphoma (CTCL) to CABE, a component of propolis
Authors: Jayakumar Arumugam , Venugopal Radjendirane , Zielinski Rafal , Rusin Aleksandra , Fokt Izabela , Skora Stanislaw , Ni Xiao , Duvic Madeleine , Priebe Waldemar
Published: August 2015

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of diseases characterized by clonal expansion of malignant T-cells in the skin. In the course of our quest to screen and identify a potent, selective anti-proliferative drug for CTCL, we discovered that caffeic acid benzyl ester (CABE), a natural component of edible plant species found in high concentrations in propolis, showed increased potency for CTCL (IC50 4 μM) in vitro compared to other tumor types such as melanoma (IC50 25 μM), glioma (IC50 25 μM), multiple myeloma (MM) (IC50 70 μM), head and neck squamous cell carcinoma (HNSCC) (IC50 25 μM), ovarian cancer (OC) (IC50 17 μM), breast carcinoma (IC50 43 μM), and Hodgkin's B-cell lymphoma (IC50 33 μM). Cell death in CTCL MJ and HH cell lines was accompanied by increased caspase-3 and poly (ADP-ribose) (PARP) cleavage and annexin V staining. There is growing evidence that CABE and its analogs exert their anticancer activity by modulating expression level of key transcription factors. Here, we evaluated the effects of CABE on the activity of different transcription factors and the expression of total and phosphorylated proteins in MJ cells by use of the transcription factor activation profiling array (TFAPA) and the reverese-phase protein array profiling (RPPA) assays. The activity of 48 transcription factors (TFs) and expression of 225 unique total and phosphorylated proteins could be monitored simultaneously by using a collection of biotin-labeled DNA probes and 225 unique antibodies. TFAPA analysis revealed that 18 TFs (including STAT1, STAT4, and RXR) were up-regulated and 3 TFs (STAT3, STAT5, and SATB1) were down-regulated to a variable extent in cells treated with 10 μM CABE for 5 h as compared to vehicle-treated control. RPPA analysis revealed 41 differentially expressed proteins between vehicle control and cells treated with 10 μM CABE. These can be functionally categorized into functional groups: DNA repair, cell cycle, apoptosis, phosphoinositide 3-kinase (PI3K)/AKT/mTOR, and receptor kinase pathways. Our results suggest that CABE targets multiple signaling pathways in CTCL in vitro, warranting the development of a pre-clinical animal model for the testing of CABE efficacy in vivo.

Acknowledgement: These studies were supported in part by the grant from Moleculin, LLC

Citation Format: Arumugam Jayakumar, Radjendirane Venugopal, Rafal Zielinski, Aleksandra Rusin, Izabela Fokt, Stanislaw Skora, Xiao Ni, Madeleine Duvic, Waldemar Priebe. High sensitivity of cutaneous T-cell lymphoma (CTCL) to CABE, a component of propolis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2096. doi:10.1158/1538-7445.AM2015-2096
Abstract 2102: TBX2 promotes rhabdomyosarcoma (RMS) tumorigenesis by repression of PTEN expression
Authors: Zhu Bo K. , Davie Judith K.
Published: August 2015

RMS is most common soft tissue sarcoma in children. We previously identified TBX2 as an oncogene and showed that TBX2 is required for tumor formation. Here, we identified the tumor suppressor PTEN as a novel target of TBX2 in RMS and normal muscle. PTEN, which regulates the PI3K-AKT pathway, is repressed in RMS. Our work shows that TBX2 functions to regulate PTEN expression and thus, PI3K-AKT signaling, to enhance the malignancy of RMS tumors.

Both quantitative real time PCR and western blot assays were used to assay PTEN expression at the level of mRNA and protein respectively. Immunofluorescence staining was performed to assay the protein expression in human RMS tumor samples. Muscle tissue slides of proliferating myoblasts were assayed by co-immunofluorescence staining, and the proliferating myoblasts were induced by activating satellite cells with cardiotoxin induced muscle damage. Reporter constructs for luciferase assay were based on PTEN promoter. Chromatin immunoprecipitation (ChIP) assays were used to detect protein binding on gene promoters. Xenograft assays were conducted to assay TBX2 function in tumor malignancy.

We have found that PTEN was up-regulated upon muscle differentiation, but little expression of PTEN was observed in RMS cells. Although TBX2 was expressed in proliferating myoblasts, it was highly down-regulated upon myogenic differentiation. Human RMS tumor samples showed a down-regulation of PTEN and an up-regulation of TBX2 compared with normal tissues. Over-expression of TBX2 repressed PTEN expression in both C2C12 myoblasts and 10T1/2 fibroblasts. Either depletion of TBX2 or a dominant negative TBX2 increased PTEN expression in RMS cells. Luciferase assays confirmed the regulation of PTEN by TBX2 and ChIP assays demonstrated that TBX2 recruited HDAC1 to the PTEN promoter for repression. The role of HDAC1 in repression of PTEN was confirmed by treatment with HDAC inhibitors, which abrogated the repression of PTEN by TBX2.

This work demonstrates that the high expression of TBX2 in RMS is involved in the activation of PI3K-AKT signaling pathway by repressing PTEN, underlying the oncogenic function of TBX2 in tumor cells.

Citation Format: Bo K. Zhu, Judith K. Davie. TBX2 promotes rhabdomyosarcoma (RMS) tumorigenesis by repression of PTEN expression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2102. doi:10.1158/1538-7445.AM2015-2102
Abstract 2110: Modulating NRAS mRNA translation by nucleic acid clamp-mediated stabilization of the 5′- UTR G-quadruplex
Authors: Hao Taisen , Brooks Tracy A.
Published: August 2015

NRAS, a proto-oncogene belonging to the RAS oncogene superfamily, is a intracellular signal cascade mediator, with intrinsic GTPase activity, functioning to initiate the MAPK cell signaling pathway. Among the RAS oncogene superfamily that is mutated in approximately 30% of all cancers, the NRAS mutation accounts for about 15% of RAS related human malignancies, particularly myeloid leukemias and cutaneous melanomas. Recently, a stable G-quadruplex (G4) was previously identified in the 5′-untranslated region (UTR) of NRAS mRNA. This G4 functioned as a translational silencer, downregulating NRAS protein and leading to the hypothesis that a small nucleic acid clamp could be optimized to facilitate the formation of specifically this G4, decrease NRAS expression, and facilitate cell death in melanoma cells. In the present study, a set of clamps were designed and examined for their ability to facilitate the formation of a G4 in the 5′-UTR sequence of NRAS. These clamps are comprised of ribonucleotides complementary to the RNA 5′- and 3′-regions flanking the G4-forming sequence held together by a small linker element. Based on binding studies consisting of electromobility shift assays and circular dichroism, an optimal flank length and linker length was chosen for cellular studies. Effects on cellular viability and NRAS expression are being examined in leukemia and melanoma cells, and RNA ChIP-Seq is being used to localize the intracellular activity of the clamps to the 5′-UTR. These nucleic acid clamps offer a high degree of selectivity for G4s over linear RNA facilitated by the small linker region; moreover, the approach of complementary nucleotides, versus small molecule-mediated G4 stabilization, allows for specificity for just one G4 out of all of the intracellular structures. This approach not only provides a solid base for developing the clamp into a non-small molecule cancer therapy, but also opens a new window for modulating oncogenic gene expression at the transcriptional or translational levels. The current study, in particular, offers a novel approach to anti-NRAS-mediated therapies for the treatment of myeloid leukemias and cutaneous melanomas.

Citation Format: Taisen Hao, Tracy A. Brooks. Modulating NRAS mRNA translation by nucleic acid clamp-mediated stabilization of the 5′- UTR G-quadruplex. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2110. doi:10.1158/1538-7445.AM2015-2110