bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B89: The significance of Vitamin D deficiency and anaerobes in prostate cancer
Authors: Oliver Tim , Blackburn Lucy , Chinegwundoh Frank
Published: October 2015

Objective: Long-term sun exposure estimates correlate with risk of PC possibly due to long-term Vitamin D deficiency diminishing macrophage function allowing persistence of low grade pathogens causing chronic inflammation leading to Proliferative Inflammatory Atrophy and then cancer. Recently infection with two low grade pathogenic organisms, teenage acne associated Vitamin D sensitive anaerobic bacterium Propionibacterium.acnes (PA) and protozoan Trichomonas vaginalis (TA), have been notable exceptions. This presentation reports a systematic review of reports on anaerobes, circumcision and the association of sun exposure in causation of PC and considers how these observations could contributing to increased PC in Africa

Methods: Pubmed searches using terms prostate or prostatic, sunshine or UVB or Vitamin D and acne or PA or TA were performed

Results: Two systematic reviews of PC and Vitamin D failed to produce a consistent association. 4/4 studies of index of long-term sun exposure involving 1568 patients and 9/12 geographic studies demonstrated that high UVB exposure reduced PC risk. 4/5 publications on PA and PC and 2/3 publications on TV and PC showed consistent increase risk of PC associated with infection. Ten studies involving 5681 patients demonstrated significant reduction of PC in circumcised individuals (OR 0.87), including one in African American Men showing lower incidence of circumcision possibly contributing to their higher frequency

Conclusion: Reduced long-term Vitamin D mediated non-specific macrophage surveillance against low-grade pathogenic anaerobes could explain these associations with PC and increasing urbanisation could be a factor in the health inequality as measured by prostate cancer incidence in African-American men.

Citation Format: Tim Oliver, Lucy Blackburn, Frank Chinegwundoh. The significance of Vitamin D deficiency and anaerobes in prostate cancer. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B89.
Abstract IA17: The Cdk4/E2F pathway drives centrosome amplification and chromosome instability in breast cancer cells
Authors: Saavedra Harold I.
Published: October 2015

Chromosome instability (CIN) instigates various malignant phenotypes, including deregulated proliferation, apoptosis and invasion to initiate and sustain carcinogenesis. A major source of CIN in cancer is centrosome amplification (CA), defined as the acquisition of abnormal number of centrosomes (3 or more) that may result in defective mitosis, chromosome missegregation and aneuploidy. CA is present in pre-malignant breast lesions and high percentages of CA correlate with metastasis to the lymph nodes. CA may facilitate breast tumorigenesis, albeit this hypothesis has to be tested. Our laboratory found that CA and binucleation, intermediates to tetraploidy, are more likely to occur in Her2+ER-PR- (Her2+) breast cancers, while triple-negative (TN or Her2-ER-PR-) display other forms of CIN, such as micronuclei, defined as missegregated whole or fragmented chromosomes. The Her2 and TN subtypes differ from good-prognosis breast cancers such as luminal in that they accumulate high frequencies of CIN. Even though all breast cancer patients respond similarly to radiation therapy, Her2+ and TN patients are more likely to recur. Our laboratory searches for sources of CA and CIN in breast tumors and found that CA and CIN are suppressed by silencing of Cdk4 and the E2F activators. We have shown that silencing of CDK4 radiosensitizes TN and Her2+ breast cancer cells by activating intrinsic apoptotic pathways. We propose that inhibiting the cell and centrosome machinery would represent future treatment modalities for breast cancer.

Citation Format: Harold I. Saavedra. The Cdk4/E2F pathway drives centrosome amplification and chromosome instability in breast cancer cells. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr IA17.
Abstract IA27: The changing landscape of U.S. cancer survivorship
Authors: Ramirez Amelie G.
Published: October 2015

More people are surviving cancer than ever, with nearly 14.5 million cancer survivors currently living in the United States, according to federal statistics. That number is expected to reach 19 million by 2024, largely due to increases in cancer diagnoses in an aging population and advances in cancer treatment and early detection. In 2005, the Institute of Medicine released From Cancer Patient to Cancer Survivor: Lost in Translation, a landmark report that highlighted a lack of best practices in caring for survivors. Since that report, several initiatives have been implemented to address the needs of the growing survivor population. However, the cancer survivorship experience isn't the same in all populations. Within medically underserved racial/ethnic populations there are several factors that impact the survivorship experience and quality of life during the survivor period. This presentation will serve as an introduction into the survivorship experiences of different racial/ethnic groups as well as some of the challenges around measuring health related quality of life within these groups.

Citation Format: Amelie G. Ramirez. The changing landscape of U.S. cancer survivorship. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr IA27.
Abstract A07: Decline in the growth of murine T-cell lymphoma via modulation of PI3K signaling pathway: Key role of quercetin and PI-103
Authors: Maurya Akhilendra Kumar , Vinayak Manjula
Published: October 2015

Deregulation in cell proliferation, oxidative status, antiapoptosis and survival are involved in development of cancer. The cellular signaling cascades mediated by Phosphatidylinositol 3-kinase (PI3K) with their ability to stimulate cell proliferation and suppress apoptosis, has been considered to play key role in tumor initiation, promotion, and progression. Therefore, use of inhibitors or antioxidants like natural flavonoids could be promising strategy to target PI3K pathway for suppression of carcinogenic process. The present study was aimed to investigate the anti-cancer activity of quercetin, a natural flavonoid and PI-103, a synthetic inhibitor in transplantable murine T-cell lymphoma. Cytotoxicity, apoptotic potential, cell survival, cell proliferation as well as antioxidant defense are evaluated in ascite cells of murine T-cell lymphoma in vivo and in primary culture. Significant decline in level of AKT1, PKCα, COX 2 as well as regulatory domain of PI3K (p85α), AKT1 and Bad, suggested implication of quercetin in regression of lymphoma by down regulation of cell proliferation and survival. Improvement of active PKCδ, p53, active caspase 3, 9 and cleaved PARP supported its cell apoptotic mechanism in cancer prevention. Additionally, decreased ROS level and LDH A activity contributes to reduced survival of cancer cells. Inhibition of p110α by PI-103 resulted in suppression of phospho-AKT and p85α level in primary culture. Modulation of various molecular targets including PI3K/AKT signaling by quercetin and PI-103 in vitro and in vivo tumor models suggests the importance and contribution of antioxidant quercetin in the prevention of cancer.

Citation Format: Akhilendra Kumar Maurya, Manjula Vinayak. Decline in the growth of murine T-cell lymphoma via modulation of PI3K signaling pathway: Key role of quercetin and PI-103. [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 A07.
Abstract A11: Crosstalk between mTORC1 and estrogen receptor in breast cancer
Authors: Alayev Anya , Salamon Rachel S. , Holz Marina K.
Published: October 2015

Approximately two thirds of all breast cancer cases are estrogen receptor (ER) positive, which underscores the dependence of cancer cells on estrogen for growth and survival. However, resistance to endocrine therapy develops in most cases. mTORC1 (the mechanistic target of rapamycin complex 1) is a critical node of estrogen signaling in the cell, however the mechanism of estrogen activation of mTORC1 is not well understood. We have previously demonstrated that mTORC1 promotes growth factor-mediated ER activation by phosphorylating ERα on Ser167. This phosphorylation, which is mediated by the mTORC1 effector kinase S6K1, is important for ERα dimerization, DNA binding and transcriptional activity, is associated with endocrine resistance and correlates with therapy response. Moreover, ERα promotes expression of S6K1, generating a feed-forward positive activation loop. Our current efforts are focused on fully understanding the nature and mechanism of the relationship between mTORC1 and estrogen pathways. Our data indicate that mTOR, raptor and ER form a complex whereby ER directly interacts with raptor. Moreover, this interaction is stimulated by estrogen as seen by co-immunoprecipitation analysis. We additionally found that ER and raptor co-localize to the nucleus upon estrogen stimulation, where they interact as detected by both immunofluorescence and cellular fractionation experiments. Our current efforts are focused on understanding the role of this interaction and the mechanism of estrogen mediated localization of raptor to the nucleus. We are also investigating the role of raptor and estrogen receptor interaction in endocrine therapy treatment and resistance.

Citation Format: Anya Alayev, Rachel S. Salamon, Marina K. Holz. Crosstalk between mTORC1 and estrogen receptor in breast 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 A11.
Abstract A25: Effect of Rab25 on Akt1 phosphorylation
Authors: Buyru Nur , Seven Didem , Dogan Soydan , Koseoglu Hikmet , Karaman Emin
Published: October 2015

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease and despite therapeutic improvements and reconstructive modalities, the overall survival rate remains relatively poor. Although, tobacco and alcohol consumption are recognized as critical risk factors, genetic and epigenetics factors and viral infections also contribute to the progression of HNSCC. Several studies have assessed the status of known oncogenes and tumor suppressor genes to identify novel genomic events in HNSCC.

Rab25 belongs to the Rab family of small GTPases. Rab25 has been described in conflicting previous studies as a promoter or suppressor of cancer. More recently, Zhang et al. reported that overexpression of Rab25 contributes to metastasis through activation of the Akt/GSK-3β/Snail pathway signaling in bladder cancer, which act as molecular switches that belong to the Ras protein superfamily and regulate vesicle trafficking in eucaryotic cells.

The phosphotidylinositol 3-Kinase (PI3K) signaling pathway plays a critical role in cellular growth, proliferation and survival. Signaling through this pathway is commonly upregulated during tumorigenesis. Akt/PKB is a Ser/Thr kinase and the central member of the PI3K/Akt signaling pathway. It is activated by phosphorylation and subsequently phosphorylates diverse growth –controlling effectors and regulates the synthesis, stability and subcellular localization of cell cycle regulators.

In this study, we investigated the phosphorylation of Akt1 and whether it occurs under the effect of Rab25 expression in HNSCC.

For this purpose we analyzed the Rab25 protein by Western Blot in 57 HNSCC tumors and corresponding non-cancerous tissue samples. To detect the effect of the Rab25 protein on Akt1 activation we also analyzed the amount of total Akt1 and phosphorylated Akt1 in the same tissue samples. Our results indicate that Rab25 is down-regulated in 56.2% of the HNSCC tumor samples compared to their normal counterparts. On the other hand, the change in Akt1 phosphorylation was in the same direction with Rab25 protein expression (p: 0.04)

Citation Format: Nur Buyru, Didem Seven, Soydan Dogan, Hikmet Koseoglu, Emin Karaman. Effect of Rab25 on Akt1 phosphorylation. [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 A25.
Abstract A32: Cell dormancy and tumorigenicity due to PTEN loss
Authors: Thompson Keyata N. , Whipple Rebecca A. , Charpentier Monica S. , Boggs Amanda E. , Bhandray Lekhana , Chakrabarti Kristi R. , Martin Stuart S. , Vitolo Michele I.
Published: October 2015

Breast cancer is the most frequent malignancy in women, and although many breast cancers are curable via surgery, approximately one quarter maintain a latent and insidious characteristic of slow growth with early metastasis. The loss of the tumor suppressor PTEN is associated with breast cancer stage, increased lymph node status, and disease-related death, and the high rate of loss in primary tumors suggests a potential role in initiation and/or progression of the disease. However, specific cellular alterations in human breast epithelium controlled by PTEN inactivation, which lead to an increased metastatic phenotype, remain poorly defined. Many breast cancers have an activated PI3K pathway either due to PTEN loss or PI3K mutation, while a large fraction of breast tumors carry oncogenic mutations that cause hyperactivation of the MAPK/ERK cascade (20%–25% ErbB2, 5% KRAS, 2% BRAF, 1% HRAS, 1% NRAS). Using the isogenic non-tumorigenic MCF-10A and MCF-10A PTEN-/- cells, we have determined that PTEN-/- cells persist in mouse xenografts while their isogenic counterparts disappear. Although the PTEN-/- cells form small, 2mm tumors, these cells do not produce large growths. Since the current view of cancer is based on a “multi-hit” hypothesis: human cancers display a multitude of genetic and epigenetic changes, and a number of such alterations are required for the step-wise progression of tumor development, the activation of both signaling pathways may cooperate to promote tumorigenesis. We therefore tested the hypothesis that the activation of the MAPK pathway in a PTEN-negative background promotes tumorgenicity. To determine the cooperativity of PTEN loss and the MAPK pathway, we have expressed activated KRAS(V12) in the MCF-10A PTEN-/- cells. The combination of PTEN loss and KRas(V12) expression resulted large tumors within 4 weeks of injection. Interestingly, we discovered that “one-hit” of either PTEN loss or active Ras leads to a cellular persistence in vivo, a characteristic that may have been previously overlooked in more genetically unstable tumor cells.

Citation Format: Keyata N. Thompson, Rebecca A. Whipple, Monica S. Charpentier, Amanda E. Boggs, Lekhana Bhandray, Kristi R. Chakrabarti, Stuart S. Martin, Michele I. Vitolo. Cell dormancy and tumorigenicity due to PTEN loss. [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 A32.
Abstract A34: GDC-0980, a dual PI3K/mTOR inhibitor, selectively inhibits NF2 mutant malignant mesothelioma (MM) cells and inhibits TOR signaling without activating Akt or ERK
Authors: Zauderer Marjorie G. , Moulik Kamalika , Cooper Jonathan , Krug Lee M. , Giancotti Filippo
Published: October 2015

Purpose: Inactivation of Merlin/NF2 is common, occurring in 45-60% of mesotheliomas. Merlin loss leads to hyperactivation of TOR signaling and dysregulation of this pathway drives tumor development and growth. Cytostatic inhibition of TOR with rapamycin in MM cells has limited impact (Lopez-Lago Mol Cell Biol 2009). Rapamycin releases two major negative feedback loops that restrain Akt-TOR signaling, thereby leading to hyperactivation of both Akt and ERK. Effective growth inhibition likely requires dual inhibition of PI3K and mTOR. We therefore sought to assess the activity of the potent and selective dual PI3K/mTOR inhibitor GDC-0980 in MM cells with respect to cell proliferation and hyperactivation of Akt and ERK.

Experimental Procedures: NF2 mutant cell lines, VAMT and JMN, and NF2 wild type cell lines, H-Meso and 211-H, were cultured in the presence of increasing concentrations of GDC-0980 for 48 hours and subjected to MTT assay. Values were normalized to untreated samples at day 0. Meso 33 and JMN malignant mesothelioma cell lines were treated with increasing doses of GDC-0980 for 2 hours and subjected to immunoblotting for P-S6, P-4E-BP1, P-Akt (S473), P-ERK, and ERK2.

Results: GDC-0980 effectively inhibited proliferation of the NF2 mutant cell lines by 40% but had little or no effect on NF2 wild type cell lines (statistically significant difference at 80 nM with p<0.006). 100 nM GDC-0980 completely suppresses activation of TOR as assessed by phosphorylation of S6 and 4E-BP1 in Meso-33 cells. Higher concentrations were required for these events in JMN cells. However, in both Meso-33 and JMN cells, these effects were not associated with overactivation of Akt or ERK.

Conclusions: GDC-0980 is a potent inhibitor of proliferation in MM cells with NF2 mutations and does not cause hyperactivation of Akt and ERK. Along with our ongoing preclinical work with cell lines and xenograft mouse models, the data from a recent phase I clinical trial with an expansion cohort in mesothelioma (NCT00854152) provide a strong rationale for the development of biomarker-driven clinical trials of GDC-0980 and other PI3K/mTOR inhibitors in mesothelioma.

This work was supported in part by Genentech.

Citation Format: Marjorie G. Zauderer, Kamalika Moulik, Jonathan Cooper, Lee M. Krug, Filippo Giancotti. GDC-0980, a dual PI3K/mTOR inhibitor, selectively inhibits NF2 mutant malignant mesothelioma (MM) cells and inhibits TOR signaling without activating Akt or ERK. [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 A34.
Abstract A48: Crosstalk between ERK2 and Akt1 in tumor cells with constitutive K-RAS activity leads to the limited response to PI3K inhibition
Authors: Toulany Mahmoud , Rodemann H. Peter
Published: October 2015

Constitutive K-RAS activity in K-RAS mutated (K-RASmut) non-small cell lung cancer (NSCLC) cells leads to resistance to EGFR targeting strategies. Analyzing the K-RAS activity status revealed that a constitutive high K-RAS activity is observed not only in K-RASmut NSCLC cells but also in head and neck squamous cell carcinoma (HNSCC) cells presenting K-RAS wild-type (K-RASwt) overexpression. Similar to K-RAS-mutated NSCLC cells, increased K-RAS activity in HNSCC cells overexpressing K-RASwt was associated with the stimulated production of the EGFR ligand amphiregulin and resistance to EGFR tyrosine kinase (EGFR-TK) inhibitors such as erlotinib. Overexpression of mutated K-RAS in HNSCC cells expressing low level of K-RASwt stimulated Akt1 phosphorylation and increased clonogenic activity. Conversely, knockdown of K-RAS in K-RASmut NSCLC cells and in HNSCC cells presenting overexpression of K-RASwt resulted in sensitization to the anti-clonogenic activity of erlotinib. K-RAS activity results in both EGFR-dependent and EGFR-independent Akt1 activity. Short-term treatment (2 h) of cells with EGFR-TK or PI3K inhibitors (erlotinib and PI-103) resulted in repression of Akt1 activation, whereas long-term treatment (24 h) with inhibitors led to reactivation of Akt1 and stimulated clonogenicity. Akt1 re-activation was MAPK-ERK2-dependent and associated with a lack of complete response to anti-clonogenic activity of PI-103. A complete response was observed when PI-103 was combined with MEK inhibitor PD98059. Together, inhibition of clonogenicity in tumor cells presenting constitutive K-RAS activity independent of K-RAS mutational status can be achieved by the combination of PI3K and MAPK inhibitors.

Supported by grants from the Deutsche Forschungsgemeinschaft [Ro527/5-1 and SFB-773-TP B02] and the Federal Ministry of Research and Education(BMBF grants 0258416, 03NUK006D) awarded to HPR as well as GRK 1302/2 (T11) awarded to MT/HPR.

Citation Format: Mahmoud Toulany, H. Peter Rodemann. Crosstalk between ERK2 and Akt1 in tumor cells with constitutive K-RAS activity leads to the limited response to PI3K inhibition. [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 A48.
Abstract A49: Inhibition of mTOR induces chemoresistance in B-cell acute lymphoblastic leukemia
Authors: Vo Thanh-Trang , Nguyen Duc , Lui Brandon , Lu Mengrou , Mallya Sharmila , Fruman David
Published: October 2015

B-ALL is the most prominent cancer in pediatric patients. Most patients are responsive to the current chemotherapy, but B-ALLs with activated oncogenic kinases including BCR-ABL, PDGFR and JAK have a high risk of relapse. Currently, patients with the BCR-ABL translocation are successfully treated when the BCL-ABL inhibitor dasatinib is added to their chemotherapy regimen. In accord, we found that dasatinib sensitizes B-ALL cell lines to drugs used during induction and consolidation phase of chemotherapy. However, dasatinib protects BCR-ABL leukemia cell lines from killing by maintenance phase drugs methotrexate and 6-mercaptopurine. This protection only occurs in cells where dasatinib reduces downstream mTOR activity. To directly test if reduced mTOR activity can account for the protection, we assessed the effects of the allosteric mTOR inhibitor rapamycin and active-site mTOR inhibitor MLN0128. Indeed, both mTOR inhibitors consistently protect B-ALL cells from killing by methotrexate and 6-mercaptopurine. Inhibitors of AKT and PI3K also result in varying degrees of chemoprotection, which correlates strongly with the degree to which they downregulate mTOR activity. The chemoprotective effect of mTOR inhibition correlates with cell cycle arrest but other mechanisms may also be involved. These data suggest that mTOR inhibition is detrimental in some chemotherapeutic combinations, whether by inhibitors directly targeting mTOR or indirectly targeting upstream effectors. The identification of such drug combination effects is an important consideration for the current use of dasatinib and future use of PI3K/AKT/mTOR inhibitors.

Citation Format: Thanh-Trang Vo, Duc Nguyen, Brandon Lui, Mengrou Lu, Sharmila Mallya, David Fruman. Inhibition of mTOR induces chemoresistance in B-cell acute lymphoblastic leukemia. [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 A49.
Abstract A52: Extracellular matrix regulation of ErbB3 in a subset of wild-type BRAF/NRAS melanoma
Authors: Rosenbaum Sheera , Capparelli Claudia , Berman-Booty Lisa D. , Gaborit Nadège , Zhan Tingting , Davies Michael A. , Setiady Yulius Y. , Yarden Yosef , Aplin Andrew E.
Published: October 2015

While the incidence of melanoma increases each year, treatment options for melanoma patients wild-type for both BRAF and NRAS (WT-WT) remain limited. The tumor microenvironment has been highly implicated in the promotion of tumor growth and proliferation; however, its precise role in melanoma is not well understood. Extracellular matrix (ECM) proteins within the tumor microenvironment have been shown to regulate many cellular pathways, including the activation of several growth factor receptors. The receptor ErbB3 is involved in the regulation of melanocyte homeostasis, and elevated ErbB3 expression in malignant melanomas correlates with reduced patient survival. In our study we demonstrate that, in a subgroup of WT-WT cells, an interaction between melanoma cells and ECM proteins within the tumor microenvironment promotes the activation of the NRG1/ErbB3 pathway, leading to phosphorylation of the downstream target AKT and increased cell growth. Furthermore, knockdown of NRG1 reduced cell viability, which was associated with decreased phosphorylation of ErbB3, its co-receptor ErbB2 and AKT. Analogous effects were obtained targeting ErbB3 with either small interfering RNAs or the neutralizing ErbB3 monoclonal antibodies, huHER-8 and NG33. Additionally, pertuzumab-mediated inhibition of ErbB2 heterodimerization decreased AKT phosphorylation, cell growth in vitro and xenograft growth in vivo. These findings are supportive of the crucial role of the ECM in regulating tumor growth through the activation of ErbB3 signaling, and establish a basis for targeting the NRG1-ErbB3-ErbB2 axis as a novel treatment strategy in a subset of malignant cutaneous melanoma.

Citation Format: Sheera Rosenbaum, Claudia Capparelli, Lisa D. Berman-Booty, Nadège Gaborit, Tingting Zhan, Michael A. Davies, Yulius Y. Setiady, Yosef Yarden, Andrew E. Aplin. Extracellular matrix regulation of ErbB3 in a subset of wild-type BRAF/NRAS melanoma. [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 A52.
Abstract B05: PI3K/mTOR pathway-dependent regulation of oxygen metabolism via pyruvate dehydrogenase (PDH)-E1alpha phosphorylation
Authors: Cerniglia George , Dey Souvik , Gallagher-Colombo Shannon M. , Daurio Natalie , Tuttle Stephen , Busch Theresa M. , Lin Alexander , Esipova Tatiana V. , Vinogradov Sergei , Koumenis Constantinos , Maity Amit
Published: October 2015

The PI3K/mTOR pathway plays a central role in coupling metabolic processes to the cellular proliferative state. In the current study we show that pharmacological inhibition of this pathway leads to a decrease in hypoxia within SQ20B human head and neck cancer xenografts. The mechanism underlying the effect appears in part to be due to reduced tumor cell oxygen consumption induced by the drug. Pharmacologic inhibitors of the PI3K/mTOR pathway or genetic inhibition of Akt/PI3K decreased the oxygen consumption rate (OCR) in transformed cell lines in vitro by 30-40%. Pharmacologic inhibition of this pathway increased phosphorylation of the E1alpha subunit of the pyruvate dehydrogenase (PDH) complex on Ser293, an inhibitory modification of this critical gatekeeper of mitochondrial respiration. Expressing wild type PTEN in a doxycycline-inducible manner in a glioblastoma cell line with mutant PTEN led to an increase in PDH-E1alpha phosphorylation and a decrease in OCR. The decrease in OCR with PI3K/Akt/mTOR inhibition was recapitulated by knocking down PDH-E1alpha expression using siRNA. Pre-treatment with dichloroacetate (DCA), a known inhibitor of the pyruvate dehydrogenase kinases (PDKs) that phosphorylate PDH-E1alpha prevented the upregulation in PDH-E1alpha phosphorylation, induced by inhibition of the pathway and also blunted the decrease in OCR. Our findings highlight an association between the PI3K/mTOR pathway and tumor cell oxygen consumption and reveal a novel link between this pathway and PDH phosphorylation. These results have important implications for understanding the effects PI3K pathway activation in tumor metabolism and also in the use of inhibitors of this pathway in cancer therapy

Citation Format: George Cerniglia, Souvik Dey, Shannon M. Gallagher-Colombo, Natalie Daurio, Stephen Tuttle, Theresa M. Busch, Alexander Lin, Tatiana V. Esipova, Sergei Vinogradov, Constantinos Koumenis, Amit Maity. PI3K/mTOR pathway-dependent regulation of oxygen metabolism via pyruvate dehydrogenase (PDH)-E1alpha phosphorylation. [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 B05.
Abstract B48: Exploiting aberrant mTOR signaling in hematological malignancies to preferentially enlarge cells for physicochemical destruction
Authors: Trendowski Matthew , Krawiec Gabriela , Fondy Thomas P.
Published: October 2015

The mammalian target of rapamycin (mTOR) pathway has received considerable attention as a potential target for cancer chemotherapy, as aberrant mTOR regulation has been found in a tremendous diversity of malignancies. Such targeted therapies are designed to inhibit mTOR, thereby decreasing oncogenic potential within the cell. However, overexpression of mTOR may also be exploited to further increase the size differential between malignant and normal cells, a hallmark that is the basis of physicochemical therapeutic approaches. Therefore, this study sought to compare the physiological responses of malignant and normal blood cells after exposure to rapamycin, a known inhibitor of mTOR. U937 human promyelocytic leukemia cells were compared with human hematopoietic stem cells (hHSCs) at varying rapamycin concentrations to assess which cell type was more sensitive to mTOR inhibition. Subsequent results indicated that while both cell lines exhibited a marked reduction in cell volume, only U937 cells were able to readily proliferate in the presence of rapamycin. These effects were readily observed in as little as 2nM rapamycin, demonstrating the profound affinity the inhibitor has for mTOR. Further, size reduction could be rescued in U937 cells using vincristine, creating a substantial size differential between malignant and normal blood cell populations. This ultimately suggests that mTOR can be exploited to preferentially enlarge malignant cells for physicochemical destruction, providing a novel therapeutic approach for leukemia and other hematological malignancies.

Citation Format: Matthew Trendowski, Gabriela Krawiec, Thomas P. Fondy. Exploiting aberrant mTOR signaling in hematological malignancies to preferentially enlarge cells for physicochemical destruction. [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 B48.
Abstract B49: mTORC2 directs breast morphogenesis through Rictor-dependent PKCα/Rac1 signaling independent of Akt
Authors: Morrison Meghan M. , Young Christian D. , Wang Shan , Sanchez Violeta M. , Rebecca Cook S. , Hicks Donna J. , Brantley-Sieders Dana M.
Published: October 2015

Akt phosphorylation is a major driver of cell survival, motility, and proliferation in development and disease, causing increased interest in upstream regulators of Akt like mTOR complex 2 (mTORC2). We used genetic disruption of Rictor to impair mTORC2 activity in mouse mammary epithelia, which decreased Akt phosphorylation, ductal length, secondary branching, cell motility, and cell survival. These effects were recapitulated with a pharmacological dual inhibitor of mTORC1/mTORC2, but not upon genetic disruption of mTORC1 function via Raptor knock-out. Surprisingly, Akt re-activation was insufficient to rescue survival, branching, or motility of mTORC2-impaired mammary epithelial cells (MECs). However, activation of the mTORC2 substrate protein kinase C (PKC)-α fully rescued branching, invasion, and survival of MECs after genetic or pharmacological mTORC2 inhibition. PKCα-mediated signaling through the small GTPase Rac1 was necessary for mTORC2-dependent mammary morphogenesis, revealing a novel role for Rictor/mTORC2 in survival and motility of untransformed MECs through an Akt-independent, PKCα/Rac1-dependent mechanism.

Citation Format: Meghan M. Morrison, Christian D. Young, Shan Wang, Violeta M. Sanchez, Cook S. Rebecca, Donna J. Hicks, Dana M. Brantley-Sieders. mTORC2 directs breast morphogenesis through Rictor-dependent PKCα/Rac1 signaling independent of Akt. [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 B49.
Abstract B50: Targeting KRASG12D colorectal cancer with combined inhibition of PI3K/mTOR and MAPK signaling
Authors: Burgenske Danielle , Monsma David , Dylewski Dawna , Scott Stephanie , Sayfie Aaron , Kim Donald , Luchtefeld Martin , Martin Katie , Stephenson Paul , Hostetter Galen , Dujovny Nadav , MacKeigan Jeffrey
Published: October 2015

Compounds validated in preclinical models frequently exhibit limited efficacy when transitioned into human trials. As a result, many patients are stratified into treatment regimens that have little impact on their disease. With the goal of establishing preclinical models that can more accurately predict tumor responses, there has been a recent emphasis to develop patient-derived xenograft (PDX) models. We strove to develop new PDX models of colorectal cancer (CRC) to test the feasibility of targeted therapy using small molecule inhibitors. Following transplantation of patient tumor specimens into athymic nude mice, sixteen PDX models were successfully established. Common somatic mutations were determined using custom gene panels and targeted with appropriate inhibitors against PI3K/AKT, mTOR and/or MAPK signaling. In four independent models, single agent therapies against PI3K and mTOR had little impact on tumor growth. Conversely, robust declines in tumor burden were universally observed in all models with MEK inhibition with the exception of one, a KRAS G12D mutant model. Within this model, tumor response was achieved only with dual inhibition of mTOR and MAPK signaling. Given the unmet clinical need to treat tumors with aberrant KRAS signaling, these results encourage further investigation into combination treatment strategies with these small molecule inhibitors.

Citation Format: Danielle Burgenske, David Monsma, Dawna Dylewski, Stephanie Scott, Aaron Sayfie, Donald Kim, Martin Luchtefeld, Katie Martin, Paul Stephenson, Galen Hostetter, Nadav Dujovny, Jeffrey MacKeigan. Targeting KRASG12D colorectal cancer with combined inhibition of PI3K/mTOR and MAPK signaling. [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 B50.
Abstract B51: The tyrphostin, NT157, suppresses insulin receptor substrates and augments therapeutic response of prostate cancer
Authors: Ibuki Naokazu , Ghaffari Mazyar , Reuveni Hadas , Pandey Mitali , Fazli Ladan , Azuma Haruhito , Gleave Martin E. , Levitzki Alexander , Cox Michael E.
Published: October 2015

Insulin-like growth factor (IGF) signaling is associated with castrate-resistant prostate cancer (CRPC) progression. Insulin receptor substrates 1 and 2 (IRS1/2) mediate mitogenic and anti-apoptotic signaling from IGF-1 receptor (IGF-1R), insulin receptor and other oncoproteins. This study demonstrates that IRS1/2 expression is increased in PCa and, persists in CRPC. Furthermore, this study assesses the anti-cancer activity of NT157, a small-molecule tyrphostin targeting IRS proteins, using androgen-responsive (LNCaP) and -independent (PC3) prostate cancer cells in vitro and in vivo. NT157 treatment resulted in dose-dependent inhibition of IGF1R activation, suppression of IRS protein expression, inhibition of IGF-1-induced AKT activation, but increased ERK activation in NT157-treated cells in vitro. These effects were correlated with decreased proliferation and increasing apoptosis of LNCaP cells and increasing G2M arrest in PC3 cells. NT157 also suppressed androgen-responsive growth, delayed CRPC progression of LNCaP xenografts and suppressed PC3 tumor growth alone and in combination with docetaxel. This study reports the first preclinical proof-of-principle data that this novel small-molecule tyrosine kinase inhibitor targeting human IRS suppresses IRS1/2 expression, delays CRPC progression, and suppresses growth of CRPC tumors in vitro and in vivo. Demonstration that IRS expression can be increased in response to a variety of stressors that may lead to resistance or reduced effect of the therapies indicate that NT157-mediated IRS1/2 down-regulation is a novel therapeutic approach for management of advanced prostate cancer.

Citation Format: Naokazu Ibuki, Mazyar Ghaffari, Hadas Reuveni, Mitali Pandey, Ladan Fazli, Haruhito Azuma, Martin E. Gleave, Alexander Levitzki, Michael E. Cox. The tyrphostin, NT157, suppresses insulin receptor substrates and augments therapeutic response of 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 B51.
Abstract B53: Targeting PI3K signaling pathway for therapeutic enhancement of verteporfin-mediated photodynamic therapy
Authors: Kraus Daniel , Chen Bin
Published: October 2015

Photodynamic therapy (PDT) induces cell injury and death through generation of reactive oxygen species (ROS) after light activation. Verteporfin is a photosensitizer that has been approved for the treatment of age-related macular degeneration and is under investigation for targeting tumor vasculature for therapy. Being primarily localized in mitochondria, verteporfin-mediated PDT induced a rapid apoptotic cell death in SVEC mouse endothelial cells by activating mitochondria-initiated cell death pathways. However, activation of phosphatidylinositol 3-kinase (PI3K) signaling pathway was also observed after verteporfin-PDT, especially at a sub-lethal dose. Furthermore, activation of PI3K signaling was correlated with cell growth after PDT. Thus, the goal of this study is to test the hypothesis that therapeutic outcome of verteporfin-PDT can be enhanced by targeting PDT-induced pro-survival PI3K signaling pathway.

We found that PI3K-mTOR pathway inhibitor NVP-BEZ235 (BEZ235) significantly inhibited PDT-induced PI3K signaling activation and combination of BEZ235 and verteporfin-PDT resulted in more cell apoptosis and greater inhibition in cell proliferation in SVEC cells. The combination therapy led to significantly more tumor growth inhibition than each individual treatment in the PC-3 prostate tumor model. Examination of tumor samples for PI3K signaling activity and functional vasculature revealed that the combination treatment caused more inhibition in PI3K signaling and reduction in functional blood vessels than verteporfin-PDT or BEZ235 treatment alone. These results indicate that targeting pro-survival PI3K signaling pathway is an effective approach for enhancing tumor response to verteporfin-PDT.

Citation Format: Daniel Kraus, Bin Chen. Targeting PI3K signaling pathway for therapeutic enhancement of verteporfin-mediated photodynamic therapy. [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 B53.
Abstract IA05: The role of glucose and lipid metabolism in growth and survival of cancer cells
Authors: Peck Barrie , Lewis Caroline A. , Schulze Almut
Published: October 2015

Aberrant metabolism has been found to be central to oncogenic transformation. Shifting metabolic pathways to favor macromolecule biosynthesis, for example de novo lipogenesis, while maintain energy production is integral to cell growth and proliferation. Alterations in metabolic activity have emerged as one of the features of cancer cells and many oncogenic signaling pathways directly regulate the activity of metabolic processes.

We have investigated the involvement of metabolic processes in the proliferation and survival of cancer cells using gene expression analysis and functional genomics. These strategies have identified metabolic alterations in cancer and highlighted selective dependencies within the glucose and lipid metabolism that support growth and survival of cancer cells. Our results demonstrate that regulation of SREBP-dependent lipid synthesis by the Akt/mTORC1 signaling axis is required for the growth and survival of cancer cells. Disruption of SREBP resulted in altered lipid composition, mitochondrial dysfunction and oxidative stress leading to the engagement of the unfolded protein response pathway (UPR), induction of apoptosis and reduced tumor growth. Importantly, activation of fatty acid desaturation through enhanced expression of stearoyl-CoA desaturase (SCD) was identified as an essential function of SREBP downstream of the Akt/mTORC1 pathway. We also found evidence that some SREBP target genes are deregulated in cancer and that SREBP and SCD are essential to support cancer cell survival under metabolically compromised conditions.

Citation Format: Barrie Peck, Caroline A. Lewis, Almut Schulze. The role of glucose and lipid metabolism in growth and survival of cancer cells. [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 IA05.
Abstract IA14: Targeting the PTEN/PI3K pathway: From mouse model to human cancer
Authors: Wu Hong
Published: October 2015

Disease relapse represents a significant problem in treating T cell acute lymphoblastic leukemia (T-ALL), particularly in the context of PTEN alterations. It is hypothesized that leukemia-initiating cells (LICs) are responsible for both T-ALL development and treatment relapse. Here, we use the Pten null T-ALL model with functionally defined blast and LIC-enriched populations to test whether T-ALL LICs are responsible for therapeutic resistance. In this model, disease is initiated by the conditional deletion of Pten in the fetal liver hematopoietic stem cells and animals develop T-ALL with 100% penetrance in the absence of activating Notch1 mutations. Besides Pten deletion, at least two subsequent key events associated with human leukemogenesis have been identified, namely β-catenin activation and a T cell receptor α-c-Myc (Tcrα/δ-c-Myc) translocation, which lead to the transformation of T progenitor cells to self-renewable LICs enriched in the CD3+c-kitmidLin- subpopulation. In contrast to LICs in acute and chronic myelogenous leukemia, in vivo labeling revealed that T-ALL LICs are actively cycling. Furthermore, we demonstrate that T-ALL LICs are biologically distinct and respond differently to Rapamycin in comparison to their differentiated blast cell progeny. Importantly, we found that co-targeting deregulated phosphoinositide 3-kinase (PI3K) and Myc pathways, two common alterations found in human T-ALL that are associated with LIC formation in vivo, provides a potent therapeutic approach to eliminate T-ALL LICs. Our study suggests that LICs are addicted to molecular events critical for their formation and can be effectively eliminated by targeting these alterations, and that T-ALL may be stratified and treated according to such molecular defects.

Citation Format: Hong Wu. Targeting the PTEN/PI3K pathway: From mouse model to human 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 IA14.
Abstract IA21: Combination treatments that include PI3K-inhibitors for the treatment of triple-negative breast cancer
Authors: Wulf Gerburg M. , Juvekar Ashish , Lyssiotis Costas M. , Hu Hai , Baek Kim , Yadegarynia Sina , Scully Ralph , Winer Eric , Asara John , Cantley Lewis C. , Matulonis Ursula
Published: October 2015

Alterations in the PI3K pathway are highly prevalent in triple-negative breast and high grade ovarian cancer, including BRCA1- and BRCA2-related disease. On the cellular level, loss of BRCA1 increases genomic instability and reliance on single strand break repair, hence creating an opportunity to treat BRCA-related TNBC or OC with PARP-inhibitors. In addition, loss of BRCA1 and/or p53 lead to relaxation of negative feed-back loops in mitogenic signaling, resulting in highly proliferative malignancies. For these reasons PARP-inhibitor Olaparib and PI3K-inhibitor NVP-BKM120 were tested in combination and found to be synergistic in mouse models of BRCA1-related BC. Surprisingly, PI3K-inhibition enhanced a DNA damage phenotype, caused by a profound decrease in DNA synthesis that could be observed after treatment with NVP-BKM120 in vivo and in vitro. The decrease in DNA synthesis was due to reduced Nucleoside synthesis resulting from a block in glycolysis that led to a drop in flux through the non-oxidative pentose phosphate pathway. In a preclinical mouse model (K14-Cre BRCA1f/fp53f/f), the combination of NVP-BKM120 and Olaparib could induce complete remissions, while PI3K-inhibitor alone marginally slowed disease progression and PARP-inhibitor alone stabilized the disease. This concept was translated into a clinical trial: BKM120/Olaparib for Triple Negative Breast Cancer or High Grade Serous Ovarian Cancer (NCT01623349; PI: Ursula Matulonis). Dose escalation for this study and accrual to an extension cohort at the MTD (NVP-BKM120 50 mg once a day in combination with Olaparib 300 mg twice a day) have been completed and a second dose escalation arm with NVP-BYL719 and Olaparib is ongoing.

Citation Format: Gerburg M. Wulf, Ashish Juvekar, Costas M. Lyssiotis, Hai Hu, Kim Baek, Sina Yadegarynia, Ralph Scully, Eric Winer, John Asara, Lewis C. Cantley, Ursula Matulonis. Combination treatments that include PI3K-inhibitors for the treatment of triple-negative breast 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 IA21.
Abstract IA25: Autophagy: A potentially druggable resistance mechanism to PI3K/mTOR inhibitors
Authors: Amaravadi Ravi
Published: October 2015

Inhibition of PI3K/mTOR signaling in cancer cells activates autophagy. Numerous preclinical models have demonstrated therapy-induced autophagy in advanced cancer promotes tumor cell survival and is a targetable resistance mechanism. Clinical trials involving the lysosomal autophagy inhibitor hydroxychloroquine (HCQ) have been launched for patients with refractory malignancies. Currently there are nearly 30 early phase clinical trials involving HCQ for a variety of malignancies in development or actively accruing patients in the United States and abroad. The results of the first 6 HCQ clinical trials (5 in humans, 1 in dogs) that represent the first deliberate attempt to modulate autophagy therapeutically in patients will be presented. This includes a phase I trial of the mTOR inhibitor temsirolimus, and hydroxychloroquine in patients with advanced melanoma which produced a low rate of grade 3-4 toxicities and a 74 % stable disease rate. The development of novel translatable pharmacodynamic assays to characterize autophagy modulation in peripheral blood cells and tumor tissue using electron microscopy, and newer serum-based approaches based on a proteomics discovery effort will be highlighted. Our efforts to synthesize a more potent second generation autophagy inhibitor Lys05, and our plans to move a Lys05 derivative into the clinic will be discussed.

Citation Format: Ravi Amaravadi. Autophagy: A potentially druggable resistance mechanism to PI3K/mTOR inhibitors. [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 IA25.