bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3211: Inhibition of autophagy potentiates cytotoxicity of CX-5461 treatment in chemoresistant epithelial ovarian cancer
Authors: Cornelison Robert , Llaneza Danielle C. , Petrova Yulia , Dobbin Zachary C. , Schneider David A. , Landen Charles N.
Published: July 2017

Epithelial ovarian cancer remains a deadly diagnosis with poor prognosis and patients succumbing to chemoresistant disease in 80% of cases. Mechanisms of chemoresistance are numerous, but we have identified ribosomal biogenesis basal machinery as being a common upregulated signaling network in response to chemotherapeutic insult. Tumors treated with chemotherapy showed dramatic increases in size and morphology of nucleoli, suggesting global changes in ribosomal synthesis with stress. We next sought to use the RNA Polymerase I inhibitor CX-5461 to identify biologic changes in targeting ribosomal machinery that may allow resensitization to chemotherapy. CX-5461 induced autophagy, senescence and mitotic catastrophe in ovarian cancer cell lines Overall, 13 ovarian cancer lines examined were highly sensitive to Pol I inhibition by MTT, with IC50s ranging from 25nM to 2μM, and chemoresistant lines were generally more sensitive to CX-5461. In p53 mutant cells CX-5461 appears to be primarily cytostatic with mitotic catastrophe being a relatively rare event accompanying cytokinesis failure. This could be indicative of the cells successfully using autophagy to decrease ribosome requirements and evade treatment. When treated in combination with chloroquine as an autophagy inhibitor IC50s decreased to 550nM in HeyA8 (from 2μM), 70nM for HeyA8MDR (from 191nM), 110nM in SKOV3 (from 595nM) and 60nM for SKOV3TR-ip2 (from 109nM) with abundant multinucleated cells, suggesting synergy between ribosomal synthesis and autophagy inhibitors in vitro. Chloroquine administration appears to push cell to mitotic catastrophe after co-administration with CX-5461, thereby enhancing cytotoxicity over cytostatic endpoints after treatment, even in multi-drug resistant cell populations. Inhibition of autophagy appears to enhance efficacy of RNA Polymerase I inhibition in both sensitive and chemoresistant populations, prompting a potential new approach to chemoresistant disease.

Citation Format: Robert Cornelison, Danielle C. Llaneza, Yulia Petrova, Zachary C. Dobbin, David A. Schneider, Charles N. Landen. Inhibition of autophagy potentiates cytotoxicity of CX-5461 treatment in chemoresistant epithelial ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3211. doi:10.1158/1538-7445.AM2017-3211
Abstract 3213: Antagonism of D2-like dopamine receptors plays a role in Onc201’s anticancer effects
Authors: Kline Christina Leah B. , Lulla Amriti , Wagner Jessica , Dicker David , Baumeister Marie , Oster Sophie , El-Deiry Wafik
Published: July 2017

ONC201/TIC10 is a first-in-class small molecule inducer of TRAIL that causes early activation of the integrated stress response and inactivates both Akt and ERK. Its promising safety profile and broad spectrum efficacy in vitro has been confirmed in Phase I/II trials in several advanced malignancies. Biochemical and reporter assays have shown that ONC201 is a selective and competitive antagonist of the D2-like receptors, specifically, dopamine receptor D2 (DRD2) and dopamine receptor D3 (DRD3) with a KD value of ~3 µM. The theme that dopamine and dopamine receptors are important in cancer has emerged in the literature. We hypothesize that ONC201’s interaction with DRD2 is critical for ONC201’s anticancer effects. Co-treating HCT116 and RKO colorectal cancer cells with ONC201 and dopamine or the selective D2-like receptor agonist sumanirole partially abrogated ONC201-induced ATF4/CHOP expression and apoptosis. Knocking down DRD2 expression using siRNA negated ONC201’s effects on viable cell count. Overexpressing DRD2 in a cancer cell line that has very low levels of DRD2, increased ONC201-induced PARP cleavage. Quantitative RT-PCR analyses showed that cells that have acquired resistance to ONC201 did not express detectable mRNA levels of the D2-like receptors. To further determine the anti-tumor potential of targeting the D2-like receptor, we treated different cancer cell lines with other D2-like receptor antagonists. Similar to ONC201, the D2-selective antagonist L-741,626 decreased cell viability and induced apoptosis in a number of cancer cell lines. In contrast to ONC201, however, L-741,626 has a poor therapeutic index. Our findings show that the ability of ONC201 to inhibit D2-like receptors contributes to ONC201’s antiproliferative and pro-apoptotic activity. Ongoing work is aimed at elucidating the mechanisms by which antagonism of D2-like receptors can promote apoptotic cell death, especially with regard to ATF4/CHOP/DR5 and Akt/ERK/Foxo3a/TRAIL, which have been shown to be stimulated in ONC201-treated and -sensitive tumor cells.

Citation Format: Christina Leah B. Kline, Amriti Lulla, Jessica Wagner, David Dicker, Marie Baumeister, Sophie Oster, Wafik El-Deiry. Antagonism of D2-like dopamine receptors plays a role in Onc201’s anticancer effects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3213. doi:10.1158/1538-7445.AM2017-3213
Abstract 3235: Development of potent and selective inhibitors for ATR: An adjuvant for DNA damage based chemotherapeutics
Authors: Kirubakaran Sivapriya , Thiruvenkatam Vijay Thiruvenkatam , Shaik Althaf
Published: July 2017

Inhibition of DNA damage checkpoint and repair function has been a challenging as well a promising approach in cancer therapy. ATR kinase is one of the key mediator of DNA damage response which induces cell cycle arrest and DNA repair via its downstream proteins. Blocking ATR has proved to prevent the Chk1 pathway from stalled replication fork and enhances the replication stress and premature mitotic entry. In addition inhibition of ATR can selectively sensitize the cancer cell to radio and chemotherapy, due to defective DNA damage signaling through the loss of ATM or p53 mutation in cancer cell. Due to its inherent role in DDR, ATR has been explored as a potential target in enhancing the effect of radiation and chemo-therapy in addition enables highly selective targeting the cancer cell through synthetic lethality.

Despite the attractiveness of ATR inhibition in the cancer therapy, specific ATR inhibitors have remained indefinable. Further, there is a limited proof of concept data for ATR inhibition. Considering these facts and challenges we will be presenting some preliminary results with respect to In-silico design, synthesis and evolution of potential and selective inhibitors for ATR.

References

Llona-Minguez, S., Hoglund, A., Jacques, S. A., Koolmeister, T. & Helleday, T. Chemical strategies for development of ATR inhibitors. Expert Rev Mol Med 9, 10 (2014).

Wagner, J. M. & Kaufmann, S. H. Prospects for the Use of ATR Inhibitors to Treat Cancer. Pharmaceuticals 3, 1311-1334 (2010).

Liu, Q. et al. Characterization of Torin2, an ATP-competitive inhibitor of mTOR, ATM, and ATR. Cancer Res 73, 2574-2586 (2013).

Citation Format: Sivapriya Kirubakaran, Vijay Thiruvenkatam Thiruvenkatam, Althaf Shaik. Development of potent and selective inhibitors for ATR: An adjuvant for DNA damage based chemotherapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3235. doi:10.1158/1538-7445.AM2017-3235
Abstract 3247: Discovery of a novel drug that affects centrosome clustering
Authors: Jaunky Dilan B. , Larocque Kevin , Suardiaz Javier Porro , Yang Dan , Furze Emma J. , Forgione Pat , Piekny Alisa
Published: July 2017

Our goal is to identify molecular regulators of a mechanism that occurs uniquely in cancer cells, and to develop a selective anti-cancer drug. Most chemotherapies are non-selective, causing severe side-effects. In additions, cancers often develop resistance to some of the more commonly used chemotherapies. To expand the repertoire of available drugs, and to design drugs that are selective, we need to identify molecules that regulate the physiological changes that occur primarily in cancer cells. For example, cancer cells in many hard-to-treat cancers have aberrant centrosomes, which may be supernumerary or fragmented. During mitosis, these aberrant centrosomes must cluster to form bipolar spindles for successful division. Thus, targeting a process like centrosome clustering is ideal, since it is not necessary in healthy cells. We synthesized a small, stable scaffold with amenability to structure-activity-relationship studies, and found several analogues with IC50 values < 50 nM, depending on the cancer cell line. Preliminary tests showed that these compounds prevent tumors from forming and/or cause their regression in vitro. We performed cell biological studies to characterize their mechanism of action. In several different types of cancer cells, these compounds cause mitotic arrest and centrosome declustering at concentrations where they have little affect on non-cancerous cells. Live imaging revealed that within minutes of adding the compounds to HeLa cells expressing GFP-tagged tubulin, we observed rapid microtubule depolymerization and centrosome declustering. After washing out the compound, microtubule polymerization recovered, but the mitotic spindles were multipolar. Adding similar concentrations of Nocodazole, a microtubule-depolymerizing drug, also caused rapid microtubule depolymerization, but after washing out the drug, the spindles were bipolar. We are in the process of identifying the molecular target of these compounds to provide crucial insight to the mechanism governing centrosome clustering, and are continuing to perform SAR studies to obtain compounds with higher efficacy and selectivity.

Citation Format: Dilan B. Jaunky, Kevin Larocque, Javier Porro Suardiaz, Dan Yang, Emma J. Furze, Pat Forgione, Alisa Piekny. Discovery of a novel drug that affects centrosome clustering [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3247. doi:10.1158/1538-7445.AM2017-3247
Abstract 3258: Genomic analyses define molecular subtype of lung squamous cell carcinoma
Authors: lee Ji won , kim Ahreum , shin Jong-Yeon , kim Young Tae , Seo Jeong-Sun
Published: July 2017

Lung squamous cell carcinoma, which account for 25 percent of all lung cancers, have not been well characterized owing to a lack of systematic understanding of molecular pathogenesis. We performed the whole-exome and transcriptome sequencing from 101 tumors and matched normal samples from Korean patients. Somatic mutations and gene expression defined two intrinsic subtypes: (1) classical subtype; (2) immunogenic subtype. Classical subtype displayed upregulation of cell cycle related genes and enriched for gene mutations (TP53, NAV3, NFE2L2, CDKN2A, PIK2CA, KEAP1 and RB1) involved in cell proliferation, squamous differentiation and oxidative stress. Immunogenic subtype had more tumor-infiltrating immune cells than classical type. More proportion of adaptive immune cells was also detected in immunogenic subtype. Immune genes, involved in adaptive immune response, were also upregulated in immunogenic subtype. Taken together, our finding revealed that each subtype has different immune mechanisms in lung squamous cell carcinoma and provides potential opportunities for therapeutic development.

Citation Format: Ji won lee, Ahreum kim, Jong-Yeon shin, Young Tae kim, Jeong-Sun Seo. Genomic analyses define molecular subtype of lung squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3258. doi:10.1158/1538-7445.AM2017-3258
Abstract 3282: Common chronic medical conditions in pancreatic cancer: impact on overall survival
Authors: Abousamra Ahmed O. , Fogelman David , Rallapalli Vijayashri , Shalaby Akram , Javle Milind , Lenzi Renato , Ho Linus , Li Donghui , Hassan Manal
Published: July 2017

Background: We aimed to categorize the most common comorbid medical conditions in pancreatic cancer (PC) patients and to determine whether these conditions have impact on the overall survival (OS).

Methods: Between January 2000 and 2014, 2165 patients with pathologically confirmed adenocarcinoma of the pancreas consented to participate in a clinico-epidemiological study at the University of Texas MD Anderson Cancer Center. We reviewed the electronic medical records of all patients to identify the prevalence of four chronic medical conditions, including systemic hypertension, hyperlipidemia, type 2 diabetes, and altered morphology of the pancreas. Prevalence of each chronic disease was assessed and median survival was estimated by using the Kaplan-Meier product-limit method, and significant differences between the survival times were determined by using the log-rank test.

Results: Among all patients, 950 (43.9%) had history of hypertension, 516 (23.8%) had hyperlipidemia, 585 (27%) had type 2 diabetes. Radiological and pathological records indicted presence of steatosis (0.4%), fibrosis (1.9%), and pancreatitis (9.9%). The prevalence of hyperlipidemia and diabetes was significantly higher in men (27.9%, 30.2%) than in women (18.2%, 22.8%) respectively; P value <.01. We found no significant variation in the prevalence of hypertension and altered pancreatic morphology between men and women. Hypertension was more frequent among African American patients while diabetes was more common among Hispanics and African Americans. No significant variations in the distribution of other conditions by ethnicity. Median survivals of PC patients by comorbidities are presented in table 1.

Conclusion: Chronic medical conditions are commonly reported by PC patients and the prevalence of these conditions may vary by gender. However, the impact of these conditions may not significantly affect the survival of the patients. The interaction treatment choices with these conditions still needs to be elaborated in future studies.

OS (months), 95%CI of PC patients by comorbiditiesComorbidityYesNoP valueHypertension10.9 (10-11.7)11.6 (10.7-12.4).09Hyperlipidemia12 (11.8-13.1)10.9 (10.2-11.6).4Diabetes Mellitus9.7 (8.4-11.1)11.4 (10.7-12.1).1

Note: This abstract was not presented at the meeting.

Citation Format: Ahmed O. Abousamra, David Fogelman, Vijayashri Rallapalli, Akram Shalaby, Milind Javle, Renato Lenzi, Linus Ho, Donghui Li, Manal Hassan. Common chronic medical conditions in pancreatic cancer: impact on overall survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3282. doi:10.1158/1538-7445.AM2017-3282
Abstract 3305: Autophagic induction through upregulation of sestrin-2 transcription and mRNA stability mediates the anticancer effect of new compound ChlA-F
Authors: Hua Xiaohui , Huang Chuanshu , Wu Xueru , Li Jingxia
Published: July 2017

ChlA-F is a novel conformation-derivative of Cheliensisin A (Chel A), which is a new styryl-lactone isolated from Chinese Herb Goniothalamus cheliensis Huand shows potent antitumor potential effect both in vitro and in vivo. However, the anticancer activity and its potential mechanisms underlying ChlA-F action have never been explored. In present study, we evaluated the potency of ChlA-F on anchorage-independent growth and its association with autophagic responses in human high grade invasive bladder cancer cells. We found that ChlA-F significantly inhibited anchorage-independent growth of human bladder cancer cells by induction of autophagy in a sestrin2(SESN2)-dependent Fashion. Our results revealed that ChlA-F treatment specifically induced SESN2 expression via increasing its both gene transcription and mRNA stability. On the one hand, ChlA-F treatment markedly attenuated Dicer protein abundance, and in turn abolished miR-27a maturation and further relieved miR-27a directly binding to SESN2 mRNA 3’UTR, thereby promoting SESN2 mRNA stabilization. On the other hand,ChlA-F treatment promoted Sp1 abundance and consequently mediated SESN2 transcription. Moreover, either knockdown of Sp-1 or ectopic expression of miR-27a could abolish the autophagic response and reversed the inhibition of anchorage-independent growth in human bladder cancer cells. These results demonstrate that anticancer effect of ChlA-F is mediated by its activating autophagic pathway through promoting both SESN2 mRNA transcription and stabilization,which offers novel insights into the anticancer effect of ChlA-F on bladder cancer and provides a therapeutic alternative against human bladder cancer.

Citation Format: Xiaohui Hua, Chuanshu Huang, Xueru Wu, Jingxia Li. Autophagic induction through upregulation of sestrin-2 transcription and mRNA stability mediates the anticancer effect of new compound ChlA-F [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3305. doi:10.1158/1538-7445.AM2017-3305
Abstract 3307: Induction of autophagy as a mechanism of therapeutic resistance in head and neck cancer
Authors: Eckers Jaimee C. , Swick Adam D. , Fowler Tyler , Skiba Justin , Nickel Kwangok P. , Kimple Randall J.
Published: July 2017

Background: In the curative setting for head and neck cancer (HNC) a commonly used treatment is radiation combined with the anti-EGFR monoclonal antibody cetuximab (CTX). However, despite decades of research into improved treatments, therapeutic resistance remains a major challenge for this malignancy with roughly 40% of patients developing recurrent disease. We are studying the molecular mechanisms by which radiation and cetuximab induce autophagy and how this process can be modulated to improve the efficacy of therapy.

Methods: We evaluated a panel of both human papillomavirus (HPV) positive and negative HNC cell lines for autophagic response to both CTX treatment and ionizing radiation (XRT). Induction of autophagy was detected by immunoblot flux assays for LC3 and p62 and by immunofluorescent staining of autophagic vesicles. siRNA knockdown of EGFR, LAMPT4B, ULK1, Beclin1 and others was used to probe the involvement of different signaling molecules. The addition of specific autophagy inhibitors, such as the ULK1 inhibitor SBI-0206965, to CTX or XRT treatment was tested to determine whether the reduction of autophagic response reduced cell survival in a clonogenic survival assay. Induction of apoptosis was analyzed by immunoblot against cleaved Caspase and PARP and AnnexinV staining.

Results: Flux assays revealed that both CTX and XRT induced autophagy in a time and dose dependent manner. Immunofluorescent staining of LC3 to identify autophagic vesicles showed that a relatively small fraction of the total cell population is able to induce this response. Specific siRNA knockdown of EGFR and LAMPT4B was able to abrogate the induction of autophagy in response to both CTX and XRT. Involvement of alternative downstream pathways involving either ULK1 and Beclin1 or p53 in response to either treatment is under investigation. To determine whether blockade of cytoprotective autophagy can help overcome therapeutic resistance, we tested specific autophagy inhibitors in combination with either CTX or XRT treatment. The addition of the ULK1 inhibitor to CTX or XRT induced apoptosis as shown by caspase activity, AnnexinV staining, and reduced cell survival in clonogenic assays.

Conclusions: Autophagy may play a critical and protective role in how head and neck cancers respond to therapeutic stress. The addition of specific autophagy inhibitors to standard treatments may provide a way to overcome resistance to therapy.

Citation Format: Jaimee C. Eckers, Adam D. Swick, Tyler Fowler, Justin Skiba, Kwangok P. Nickel, Randall J. Kimple. Induction of autophagy as a mechanism of therapeutic resistance in head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3307. doi:10.1158/1538-7445.AM2017-3307
Abstract 3325: Ginkgetin, a biflavonoid derived from leaves of Ginkgo biloba, induces autophagic cell death in non-small cell lung cancer via p62
Authors: Lou Jian Shu , Bi Cathy , Chan Gallant , Dong Tina , Tsim Karl
Published: July 2017

Chemotherapeutic drugs in the treatment of non-small-cell lung carcinoma (NSCLC) are usually mediated by induction of apoptosis; this usually results in drug resistant during the therapy. Many compounds from natural resource have been shown to trigger autophagy in promoting cell death, and therefore which could be a novel treatment for cancer. Ginkgetin, a biflavonoid from Ginkgo biloba leaves (Ginkgoaceae), was shown its anticancer effects recently. The leaf of G. biloba is being recorded as a safe herbal drug in Pharmacopoeia from China and Europe. Here, the possible development of ginkgetin as an anticancer drug was demonstrated. Ginkgetin induced the death in A549 (NSCLC) with an IC50 lower than that of cisplatin. This anticancer effect of ginkgetin was also illustrated in NSCLC xenograft nude mice model. Transmission electronic microscope revealed that ginkgetin-induced autophagy was the main cause of cell death. Autophagy inhibitors, 3-methyladenine and chloroquine but not apoptosis inhibitor Z-VAD-FMK, rescued ginkgetin-induced cell death. Reciprocally, the induction of autophagy by rapamycin promoted ginkgetin-induced cell death, as well as the formation of p62-TRAF6-mTOR. During autophagy, p62 is hypothesized to be a target of ginkgetin-induced autophagic cell death. This notion is supported by several lines of evidence. The application of ginkgetin blocked fully the expression of p62 in cultured A549, and in contrast the over expression of p62 reduced ginkgetin-induced autophagy and cell death concomitantly with the decline on autophagosome formation. In parallel, the modulation on p62 expression could regulate Nrf2 activity and ROS level in the presence of ginkgetin. Thus, autophagy could act as an inducer in ginkgetin-induced cell death, and p62 was proposed to be a possible target during this process. Here, ginkgetin exhibited promising anticancer effect in NSCLC via autophagy, a signaling very different to orthodox chemotherapeutic drug cisplatin. Besides, ginkgetin is a phytochemical from G. biloba that is considered as a safe herbal supplement, and no obvious toxicity was observed in xenograft nude mice. Therefore, ginkgetin is proposed to be a potential compound for the development of novel anticancer drug. Acknowledgements: This study was supported by Hong Kong Research Grants Council Theme-based Research Scheme (T13-607/12R), GRF (663012, 662713, M-HKUST604/13), TUYF15SC01 and Foundation of The Awareness of Nature (TAON12SC01) to Karl Tsim.

Citation Format: Jian Shu Lou, Cathy Bi, Gallant Chan, Tina Dong, Karl Tsim. Ginkgetin, a biflavonoid derived from leaves of Ginkgo biloba, induces autophagic cell death in non-small cell lung cancer via p62 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3325. doi:10.1158/1538-7445.AM2017-3325
Abstract 3328: Protochadherin 7 acts through SET and PP2A to potentiate MAPK signaling by EGFR and KRAS during lung tumorigenesis
Authors: Zhou Xiaorong , Updegraff Barrett L. , Guo Yabin , Peyton Michael , Girard Luc , Larsen Jill E. , Xie Xian-Jin , Zhou Yunyun , Hwang Tae Hyun , Xie Yang , Rodriguez-Canales Jaime , Villalobos Pamela , Behrens Carmen , Ignacio Wistuba I. , Minna John D. , O'Donnell Kathryn A.
Published: July 2017

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-associated deaths worldwide. Given the efficacy of membrane proteins as therapeutic targets in human malignancies, we examined cell-surface receptors that may act as drivers of lung tumorigenesis. Here we report that Protocadherin 7 (PCDH7), a transmembrane receptor and member of the Cadherin superfamily, is frequently overexpressed in NSCLC tumors, and high expression of PCDH7 is associated with poor clinical outcome. PCDH7 overexpression synergizes with KRAS and EGFR to induce MAPK signaling and tumorigenesis. Conversely, PCDH7 depletion suppresses ERK activation, sensitizes cells to MEK inhibitors, and reduces tumor growth. PCDH7 potentiates ERK signaling by facilitating interaction of protein phosphatase PP2A with its potent inhibitor, the SET oncoprotein. By establishing a previously unanticipated oncogenic role for PCDH7 in lung tumorigenesis, these results provide proof-of-concept support for the development of novel therapies that target PCDH7 at the cell surface of NSCLC cells. Experiments to evaluate the role of Pcdh7 in Kras-mediated lung tumorigenesis in vivo using autochthonous mouse models, which we expect to lend further support for therapeutic targeting of this protein, are in progress.

Citation Format: Xiaorong Zhou, Barrett L. Updegraff, Yabin Guo, Michael Peyton, Luc Girard, Jill E. Larsen, Xian-Jin Xie, Yunyun Zhou, Tae Hyun Hwang, Yang Xie, Jaime Rodriguez-Canales, Pamela Villalobos, Carmen Behrens, Wistuba I. Ignacio, John D. Minna, Kathryn A. O'Donnell. Protochadherin 7 acts through SET and PP2A to potentiate MAPK signaling by EGFR and KRAS during lung tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3328. doi:10.1158/1538-7445.AM2017-3328
Abstract 3329: Combinatorial blockade of ERBB receptors in HER2 low breast cancer
Authors: Berdiel-Acer Mireia , Reinz Eileen , Abnaof Khalid , Burmester Sara , Will Rainer , Korf Ulrike , Wiemann Stefan
Published: July 2017

Large number of breast cancer patients clinically classified as HER2 negative, show low/moderate levels of HER2 along with other ERBB receptors. Concomitant blockade of EGFR, ERBB2 and ERBB3 with specific therapeutic antibodies (cetuximab, trastuzumab/pertuzumab and lumretuzumab, respectively) appears as a beneficial approach to improve survival of patients who have failed to previous treatment strategies. Additionally, ERBB3 expression has been reported as a trastuzumab resistance mechanism in HER2 positive subtypes.We have confirmed a specific pattern of ERBB receptors expression in different breast cancer subtypes. Individual and combined blockade of the receptors with therapeutic antibodies has been tested in vitro using a metabolic viability assay (Cell Titer Glo) and their effects in cell cycle status measured by BrdU staining. All four therapeutic antibodies bind to the respective extracellular domains inhibiting downstream signaling pathways. Response to individual treatment is cell dependent and correlates with EGFR expression in the triple negative MDA-MB-468 but not in luminal T47D cancer cell line. Response of T47D cells to lumretuzumab is higher when combined with pertuzumab or trastuzumab, suggesting ERBB2/ERBB3 dimer as the most relevant one, an effect more evident upon ectopic addition of NRG1 (only ligand for ERBB3). Long exposure of MDA-MB468 cells to cetuximab induces ERBB3 expression and increases its sensitivity to cetuximab when combined. As well as, in the HER2+ BT474 cancer cell line resistant to trastuzumab, higher levels of ERBB3 also make cells more sensitive to alternative anti-ERBB therapies. To establish the role of ERBB4 (no specific therapeutic antibody) in the whole ERBB network, stable knock-down regulation (shRNA) has been performed in T47D cells. Although treatment of HER2 overexpressing breast tumors has been successful, targeting other ERBB members in a HER2 moderate/low scenario seems to be a promising approach in combinatorial therapies; even in resistant cell lines. Thus, better characterization of ERBB network should help to pave the way for a personalized treatment of HER2 low breast cancer. [U.K.: Deceased March, 2016]

Citation Format: Mireia Berdiel-Acer, Eileen Reinz, Khalid Abnaof, Sara Burmester, Rainer Will, Ulrike Korf, Stefan Wiemann. Combinatorial blockade of ERBB receptors in HER2 low breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3329. doi:10.1158/1538-7445.AM2017-3329
Abstract 334: PTEN-L regulates epithelial growth and macrophage function
Authors: Wolfe Andrew L. , Hopkins Benjamin D. , Riquelme Sebastián A. , Kitur Kipyegon , Ozturk Sait , Kang Kyeongah , Remark Romain , Rahman Adeeb , Lin Chyuan-Sheng , Merad Miriam , Szabolcs Matthias , Chen Shu-Hsia , Prince Alice , Parsons Ramon
Published: July 2017

PTEN is among the most frequently mutated and deleted tumor suppressor genes in many malignancies, including breast cancer. An alternatively translated long form of PTEN, termed PTEN-L, has divergent functionality from PTEN, although its function at the organism level has not been studied. Here, we report a knockout mouse with specific ablation of PTEN-L expression but intact expression of PTEN. These mice display mammary ductal hyperplasia characterized by increased luminal growth and increased numbers of macrophages in the surrounding stroma. Macrophages are particularly affected by PTEN-L loss, with significant changes to their secretomes and functional deficiencies in clearing bacterial infections, consistent with a shift toward an M2-like polarization. Overall, these findings demonstrate that PTEN-L has unique functions in regulating mammary epithelial growth and macrophage functionality that are independent of canonical PTEN.

Citation Format: Andrew L. Wolfe, Benjamin D. Hopkins, Sebastián A. Riquelme, Kipyegon Kitur, Sait Ozturk, Kyeongah Kang, Romain Remark, Adeeb Rahman, Chyuan-Sheng Lin, Miriam Merad, Matthias Szabolcs, Shu-Hsia Chen, Alice Prince, Ramon Parsons. PTEN-L regulates epithelial growth and macrophage function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 334. doi:10.1158/1538-7445.AM2017-334
Abstract 3347: Exploring the role of ASXL family of genes in enabling oncogenic AR-signaling in prostate cancer
Authors: Parolia Abhijit , Cao Xuhong , Chinnaiyan Arul
Published: July 2017

Prostate cancer (PCa) is the second leading cause of cancer-related mortality in North American men. In recent years, there has been mounting evidence establishing the centrality of epigenetic mechanisms in PCa initiation and progression. Accordingly, various epigenetic genes have been described to collaborate with the androgen receptor (AR) in enabling its oncogenic transcriptional program and aberrantly restoring its activity in metastatic castration resistant PCa (mCRPC). Concordantly, our lab has recently described two epigenetic genes, BRD4 & MLL2, as key co-activators of the AR signaling complex. Furthermore, we have demonstrated the therapeutic benefits of inhibiting the activity of these genes in advanced PCa. Thus, in a setting where invariably all metastatic PCa patients progress to evolve resistance to anti-AR therapy, epigenetic genes emerge as potent co-targets with the promise to improve patient outcomes. To To identify novel AR-collaborating genes, as part of a multi-institutional consortium, our lab had performed comprehensive molecular profiling of 150 mCRPC patient tumors. This study revealed multiple genetic aberrations in chromatin modifier genes. Interestingly, this list comprised of recurrent mutations in the ASXL family of genes in about ~5% of the cases. ASXL family members are epigenetic scaffolding proteins that assemble chromatin modifiers and transcription factors to specific genomic loci with histone modifications. Although intricately involved in the genesis of acute myeloid leukemia, hitherto, no study has comprehensively described the role of ASXL genes in PCa biology. Two members of this family, ASXL1 and ASXL2, are robustly expressed in PCa. Co-immunoprecipitation assays revealed that these proteins also reside in the AR-signaling complex. Notably, siRNA-mediated inhibition of these genes dramatically attenuated proliferation of AR-dependent PCa cells, but had minimal effect on non-neoplastic prostate cells. These preliminary results strongly implicate ASXL genes in the oncogenic re-programming of AR-activity and warrant further investigation towards exploring of their therapeutic value in currently incurable mCRPC.

Citation Format: Abhijit Parolia, Xuhong Cao, Arul Chinnaiyan. Exploring the role of ASXL family of genes in enabling oncogenic AR-signaling in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3347. doi:10.1158/1538-7445.AM2017-3347
Abstract 336: PIK3CB/p110B is a survival factor in glioblastoma
Authors: Pridham Kevin J. , Guo Sujuan , Sheng Zhi
Published: July 2017

Glioblastoma multiforme (GBM) is lethal even after surgical removal of the tumor, radiation, and chemotherapy. Residual tumor cells form an intractable tumor in nearly all patients within two years. Recurrent GBM is incurable due to resistance to current therapies. Inhibitors of PI3K (phosphatidylinositol-4,5-biphosphate 3-kinase)-a signaling pathway that causally contributes to tumor formation/recurrence-have been used to treat recurrent GBMs and achieved modest clinical effect. This is perhaps attributed to non-selective inhibition of PI3K isoforms, which yields intolerable toxicity. Class IA PI3K isoforms include three catalytic subunits (PIK3CA, B, or D that encodes p110α, β, or δ) and three regulatory subunits (PIK3R1-3 that encodes p85 isoforms). Our recent work indicates that PIK3CB levels positively correlate with the chances/risk of GBM recurrence, while being inversely associated with patient prognosis. This suggests that PIK3CB/p110β is important for GBM cell survival. To test this hypothesis, we first measured the expression of PI3K isoforms in a panel of 9 GBM cell lines. We found that U87MG, SF295, and U251 expressed much higher levels of p110β, coinciding with the levels of phosphorylated AKT. We then knocked down PIK3CA, B, and D in human U87MG cells and found that only depletion of PIK3CB/p110β resulted in an inactivation of downstream AKT. Moreover, knockdown of PIK3CB/p110β, but not other isoforms, induced substantial growth inhibition in U87MG, SF295 and U251 cells. This is congruent with the result that inhibition of PIK3CB/p110β activated apoptosis in U87MG cells. We also report that treatment of p110βhigh GBM cells with isoform specific inhibitors selectively represses the viability of these cells. Finally, we report that ectopic expression of p110β, but not p110α or δ, partially rescued U87MG cells from growth inhibition induced by TGX-221, a p110β-selective inhibitor. Collectively, our results demonstrate that PIK3CB/p110β is an important selective survival factor in GBM, underscoring the divergent roles of PI3K isoforms in GBM disease progression/recurrence and future therapeutic intervention.

Citation Format: Kevin J. Pridham, Sujuan Guo, Zhi Sheng. PIK3CB/p110B is a survival factor in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 336. doi:10.1158/1538-7445.AM2017-336
Abstract 3365: Epigenetic inactivation of PTPRT and sensitivity to STAT3 inhibition in lung cancer
Authors: Sen Malabika , Kindsfather Audrey , Herman James G.
Published: July 2017

Signal Transducers and Activators of Transcription-3 (STAT3), a potent oncogenic transcription factor is persistently activated in several malignancies including lung cancer. Protein Tyrosine Phosphatase Receptor-T (PTPRT) is an endogenous inhibitor of STAT3 transcriptional activity, and is methylated in many types of human cancer. Loss-of-function of PTPRT by promoter methylation contributes to STAT3 mediated growth and survival and represent one of the plausible mechanism of STAT3 hyperactivation. We report identification of hypermethylation in CpG islands of the PTPRT promoter which correlates with its transcriptional silencing as well as expression of pSTAT3 protein and STAT3 target genes in both lung cancer cell lines and primary human tumors. Analyses of the TCGA (The Cancer Genome Atlas) data revealed that PTPRT promoter is frequently hypermethylated in a subset of lung squamous cell carcinoma and approximately 25% of adenocarcinoma tumors in association with downregulation of PTPRT mRNA expression. This observation was verified in vitro using lung cancer cell lines. Out of the 7 lung cancer cell lines examined, one lung cancer cell line showed lack of methylation (only unmethylated sequences) of the PTPRT promoter region and revealed mRNA expression (H520). All 6 cell lines which showed PTPRT promoter methylation had nearly absent PTPRT mRNA and had high levels of pSTAT3Tyr705, while H520 had little or no pSTAT3Tyr705 protein expression. Silencing of PTPRT using siRNA in H520, where PTPRT was not endogenously silenced by promoter hypermethylation, resulted in the upregulation of the STAT3 target genes such as cyclin D1 and Bcl-XL mRNA and protein expression as well as increased pSTAT3Tyr705 level. Analyses of the methylation status in the PTPRT promoter region in primary lung tumor samples revealed methylation in one of the 3 tumor samples. This correlated with increased STAT3 target genes (cyclin D1 and Bcl-XL) mRNA expression. In lung cancer cell lines, PTPRT promoter methylation is associated with sensitivity to STAT3 inhibition. Our data suggests that silencing of PTPRT by promoter hypermethylation is a frequent mechanism of STAT3 hyperactivation, and targeting STAT3 may be an effective molecular targeted approach in the treatment of this subset of lung cancer.

Citation Format: Malabika Sen, Audrey Kindsfather, James G. Herman. Epigenetic inactivation of PTPRT and sensitivity to STAT3 inhibition in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3365. doi:10.1158/1538-7445.AM2017-3365
Abstract 3380: Synthetic lethal interaction between ARID1A mutation and BET bromodomain inhibition in ovarian clear cell carcinoma
Authors: Berns Katrien , Caumanns Joseph J. , Hijmans E Marielle , Gennissen Annemiek , Evers Bastiaan , Wisman Bea A. , Meersema Gert Jan , Lieftink Cor , Beijersbergen Roderick L. , Itamochi Hiroaki , Zee Ate G. van der , Jong Steven de , Bernards René
Published: July 2017

Introduction:

Current treatment for advanced stage ovarian clear cell cancer is severely hampered by a lack of effective systemic therapy options, leading to a poor outlook for these patients. Given that ARID1A is inactivated by mutation in over 50% of ovarian clear cell carcinomas, we pursued an ARID1A synthetic lethal screening strategy to identify druggable targets in OCCC.

Experimental procedures:

We performed synthetic lethal kinome short hairpin (shRNA) screens in a large panel (n=14) of OCCC cell lines having different ARID1A mutation status. Hit validation was performed with isogenic ARID1A ko cell line pairs and in (patient-derived) xenograft mouse models.

Summary of the data:

We show here that BRD2 inhibition is synthetic lethal with ARID1A mutation in ovarian clear cell cancer cells. Importantly, inhibiting the BET family of proteins, to which BRD2 belongs, with small molecules specifically inhibits proliferation of ARID1A mutated cell lines both in vitro and in ovarian clear cell cancer xenografts and patient-derived xenograft models. We demonstrate that ARID1A loss leads to upregulation of the WNT ligand WNT10B, possibly causing a WNT dependency in the ARID1A mutant lines. BET inhibitors cause a reduction in WNT10B expression and WNT target genes such as MYC, JUN and WISP1, providing a potential explanation for the observed synthetic lethal interaction with ARID1A loss.

Conclusions:

Our study uncovered a new synthetic lethal interaction between ARID1A mutation and BET bromodomain inhibition, suggesting a new treatment strategy for ARID1A mutant ovarian clear cell carcinomas.

Citation Format: Katrien Berns, Joseph J. Caumanns, E Marielle Hijmans, Annemiek Gennissen, Bastiaan Evers, Bea A. Wisman, Gert Jan Meersema, Cor Lieftink, Roderick L. Beijersbergen, Hiroaki Itamochi, Ate G. van der Zee, Steven de Jong, René Bernards. Synthetic lethal interaction between ARID1A mutation and BET bromodomain inhibition in ovarian clear cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3380. doi:10.1158/1538-7445.AM2017-3380
Abstract 3385: Genomic landscapes of pulmonary sclerosing hemangioma
Authors: Jung Seung-Hyun , Kim Min Sung , Shin Sun , Han Mi-Ryung , Cho Yu Jin , Kim So Youn , Lee Sug Hyung , Chung Yeun-Jun
Published: July 2017

Pulmonary sclerosing hemangioma (PSH) is a benign tumor that usually presents as a solitary, well-defined mass in the lung. The PSH predominantly affects females with a higher incidence in the Far East. Histologically, the tumor cells in PSH consist of two cell types (cuboidal epithelial and polygonal stromal cells). Immunohistochemical and ultrastructural studies have identified that both cells are derived from undifferentiated respiratory epithelium that is the histologic origin of lung adenocarcinoma as well. Previous studies have shown that PSH and adenocarcinoma in the lung share some immunohistochemical and genetic features. However, as for somatic mutations, whereas many driver genes for lung adenocarcinomas have been identified, there have not been any candidate driver mutations identified in PSHs, except for low frequency mutations in β-catenin and TP53. Frequent somatic mutations identified in lung adenocarcinomas such as KRAS and EGFR have not been detected in PSH, suggesting that genomic alterations of these two lung tumors might be different from each other. Also, there is no evidence of PSH progression to lung cancers. These earlier data indicate that despite the common cellular origin of PSH and lung adenocarcinoma, genetic mechanisms for their development may be different. Based on the established concept that PSH is a true tumor, we hypothesize that it may harbor somatic mutations. In this study, we conducted whole exome sequencing of 44 PSHs and identified recurrent somatic mutations of AKT1 (43.2%) and β-catenin (4.5%). We used a second subset of 24 PSHs to confirm the high frequency of AKT1 mutations (overall 31/68, 45.6%; p.E17K, 33.8%) and recurrent β-catenin mutations (overall 3/68, 4.4%). Of the PSHs without AKT1 mutations, two exhibited AKT1 copy gain. AKT1 mutations existed in both epithelial and stromal cells. In two separate PSHs from one patient, we observed two different AKT1 mutations, indicating they were not disseminated but independent arising tumors. Since the AKT1 mutations were not found to co-occur with β-catenin mutations (or any other known driver alterations) in any of the PSHs studied, we speculate that this may be a single most common driver alteration to develop PSHs. Our study revealed genomic differences between PSHs and lung adenocarcinomas including a high rate of AKT1 mutation in PSHs. These genomic features of PSH discovered in the present study provide clues to understanding the biology of PSH and for differential genomic diagnosis of lung tumors.

Citation Format: Seung-Hyun Jung, Min Sung Kim, Sun Shin, Mi-Ryung Han, Yu Jin Cho, So Youn Kim, Sug Hyung Lee, Yeun-Jun Chung. Genomic landscapes of pulmonary sclerosing hemangioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3385. doi:10.1158/1538-7445.AM2017-3385
Abstract 34: A MET x MET bispecific antibody that induces receptor degradation potently inhibits the growth of MET-addicted tumor xenografts
Authors: DaSilva John
Published: July 2017

Aberrant regulation of MET receptor tyrosine kinase signaling is associated with development and progression of various human tumors. Elevated MET signaling during tumorigenesis results from MET amplification, mutation or up-regulation of the ligand, HGF. MET amplification is thought to be a key driver of oncogenesis in non-small cell lung cancers (NSCLC) and oesophagogastric malignancies. In addition, mutations resulting in exon 14 deletion of MET have been described as oncogenic drivers in a subset of NSCLC. Both preclinical and recent clinical results indicate that tumors harboring these genetic alterations respond to MET inhibitors, validating MET as a cancer driver.

We have developed a novel bispecific antibody that binds to two distinct epitopes on MET. The METxMET bispecific antibody blocks HGF binding and exhibits very low agonist activity (much weaker than either of its parental antibodies). Furthermore, the METxMET bispecific antibody effectively promotes MET degradation, thereby inhibiting ligand-independent signaling in MET-amplified tumor cells. The METxMET bispecific antibody exhibits strong anti-tumor efficacy in xenograft models harboring MET genetic alterations, either completely inhibiting tumor growth (EBC1 MET-amplified NSCLC) or promoting substantial tumor regression (SNU5 MET-amplified gastric cancer, Hs746T MET-amplified/MET exon 14 skip gastric cancer). Analysis of lysates from SNU5 tumors treated with the METxMET bispecific antibody confirms its ability to effectively promote MET degradation in vivo. Finally, the METxMET bispecific antibody strongly inhibits the growth of a glioblastoma xenograft model (U118) driven by autocrine HGF signaling. In summary, we have generated a novel METxMET bispecific antibody that potently inhibits the growth of MET-dependent tumor xenografts. Our data suggest that antibody-mediated MET degradation may be an effective clinical strategy in tumors harboring MET genetic alterations.

Citation Format: John DaSilva. A MET x MET bispecific antibody that induces receptor degradation potently inhibits the growth of MET-addicted tumor xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 34. doi:10.1158/1538-7445.AM2017-34