bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 581: Feasibility test of KRAS mutation in urine circulating tumor DNA in metastatic pancreatic ductal adenocarcinoma
Authors: Kwon Min Jeong , Kim Min Kyeong , Woo Sang Myung , Yoon Kyong-Ah , Kim Yun Hee , Park Boram , Joo Jung Nam , Park Sang Jae , Kong Sun-Young
Published: August 2018

Circulating tumor DNA (ctDNA) has been known to be released from tumor cells and evaluated as potential biomarkers for therapeutic responses. In our previous study, we selected KRAS mutation and evaluated applicability as a prognostic marker through the quantitative analysis of plasma ctDNA. Then we proved that KRAS mutation of ctDNA from plasma is significant biomarker for prediction of clinical outcome in pancreatic ductal adenocarcinoma (PDA). Here we investigated whether KRAS mutation in urine ctDNA had the prognostic impact as shown of plasma ctDNA. Of the 106 patients enrolled, 67 were males and median age was 66 years. Total of 51 PDA has been enrolled in this study and the median age was 63 years old and 30 males (58.8%). Urine was separated by established centrifugation method and ctDNA were extracted using QIAamp Circulating Nucleic Acid Kit (Qiagen, Germany) from 4 mL of urine. Extracted ctDNA was quantified using the Qubit dsDNA HS Assay Kit (Thermo Fisher Scientific, USA). QX200 Droplet Digital PCR System (Biorad, USA) was applied to measure frequency of KRAS mutation by KRAS screening multiplex droplet digital PCR kit, which covers seven common mutation sites (Biorad, USA). Mutant concentration and fractional abundance were analyzed by QuantaSoft software (Biorad, USA). There was no significant difference between resectable (N=21), locally advanced (N=11) and metastatic (N=19) groups. When compared high versus low KRAS mutation concentration and KRAS fractional abundance group in each stage, high KRAS mutation groups showed short overall survival (p = 0.0321) in metastatic group. However, the correlation between plasma and urine was low (r=0.193) in metastatic group. This study represented the possibility of KRAS mutation concentration and fractional concentration of urine ctDNA as prognostic factors in metastatic PDA. Urine cfDNA role has not been well investigated in PDA. Urine is easy to obtain and is not well known for its mechanism. Therefore, we have conducted a pilot study and we will explore KRAS mutation status in urine ctDNA in further studies. (This study was supported by National Cancer Center, Korea, Grant no. 1510203.)

Citation Format: Min Jeong Kwon, Min Kyeong Kim, Sang Myung Woo, Kyong-Ah Yoon, Yun Hee Kim, Boram Park, Jung Nam Joo, Sang Jae Park, Sun-Young Kong. Feasibility test of KRAS mutation in urine circulating tumor DNA in metastatic pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 581.
Abstract 5812: Synergistic induction of urinary bladder cell death and reduction of drug resistance in vitro and effective control of xenograft tumor growth in vivo by a triple combination of gemcitabine, cisplatin, and romidepsin
Authors: Wang Hwa-Chain R. , Pattarawat Pawat
Published: August 2018

Human urinary bladder cancer is the fifth most commonly diagnosed cancer in the United States. Long-term survival of patients is still suboptimal with current therapeutic regimens failing to impede drug resistance and recurrence. Thus, it is urgent to develop therapeutic regimens that effectively control tumor growth, drug resistance, and recurrence to reduce the morbidity and mortality of this disease. We investigated the efficacy of combination regimens to control various human urinary bladder cancer cells in vitro and cell-derived xenografts in vivo. Our studies revealed, for the first time, a combination of gemcitabine plus cisplatin and romidepsin effective in synergistically inducing cell death and reducing drug resistance in vitro. The enhanced Ras-ERK-Nox pathway played an essential role in mediating signals to elevate reactive oxygen species, leading to enhanced caspase activation, enhanced DNA damage and oxidation, and reduced glutathione, which synergistically increased cell death and reduced drug resistance in cells treated with combined gemcitabine, cisplatin, and romidepsin. The unfolded protein response also played a role in the modulation of cyto-protection and cell death through the combined regimen. In vivo studies verified the efficacy of gemcitabine plus cisplatin and romidepsin in control of xenograft tumor growth in immune-deficient mice. Hence, our results lead us to suggest that a combination of gemcitabine, cisplatin, and romidepsin should be seriously considered as an advanced regimen over the conventional gemcitabine plus cisplatin regimen for controlling the development and recurrence of human urinary bladder cancer.

Citation Format: Hwa-Chain R. Wang, Pawat Pattarawat. Synergistic induction of urinary bladder cell death and reduction of drug resistance in vitro and effective control of xenograft tumor growth in vivo by a triple combination of gemcitabine, cisplatin, and romidepsin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5812.
Abstract 5815: Aldose reductase inhibition prevents doxorubicin-induced inflammatory response in endothelial cells and macrophages
Authors: Sonowal Himangshu , Saxena Ashish , Ramana Kota V. , Srivastava Satish K.
Published: August 2018

Anthracycline class of chemotherapeutic drugs such as doxorubicin and daunorubicin has been known to be effective in the therapy of various types of cancer. However, in certain cancers such as colon cancer, the use of anthracyclines is restricted due to acquired drug resistance, which requires high amounts of drugs that cause severe toxic side effects. We have recently demonstrated that aldose reductase (AR) inhibitor, fidarestat, increases the sensitivity of doxorubicin towards colon cancer cells death in vitro and in vivo and decreases cardiotoxicity. However, the mechanisms through which AR inhibitor prevents doxorubicin-induced toxicity is not understood. We have examined how AR inhibition prevents doxorubicin-induced endothelial and cardiac toxicity along with inflammatory response in in vitro and in vivo models. Our results demonstrate that fidarestat prevents doxorubicin-induced oxidative stress, endothelial cell death, and monocyte adhesion. Further, fidarestat prevents the activation of NF-κB-dependent expression of endothelial cell markers ICAM-1 and VCAM-1 and expression of various inflammatory cytokines and chemokines in human vascular endothelial cells. In addition, fidarestat prevented the doxorubicin-induced decrease in eNOS and increase in iNOS expression. Similarly, AR inhibition prevented doxorubicin-induced endothelial dysfunction, cardiac hypertrophy, and cardiomyocyte injury in mice. Fidarestat also prevented doxorubicin-induced activation of monocytes and macrophages to proinflammatory phenotype in culture as well as in mouse models. Thus, our results suggest that by preventing doxorubicin-induced inflammatory as well as oxidative stress signals, fidarestat decreases cardiotoxic effects of doxorubicin. This is a novel adjuvant therapy of cancer using aldose reductase inhibitors with anthracyclines that would increase cancer therapeutic efficacy and decrease cardiotoxic side effects.

Citation Format: Himangshu Sonowal, Ashish Saxena, Kota V. Ramana, Satish K. Srivastava. Aldose reductase inhibition prevents doxorubicin-induced inflammatory response in endothelial cells and macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5815.
Abstract 5821: Atorvastatin antagonizes carboplatin, synergizes with the glycolytic inhibitor PFK-158, and induces lipid laden multilamellar bodies in ovarian cancer
Authors: Kalogera Eleftheria , Roy Debarshi , Bakkum-Gamez Jamie N. , Cliby William A. , Dowdy Sean C. , Shridhar Viji
Published: August 2018

Objectives: To investigate the antitumor potential of the widely used anticholesterol drug Atorvastatin (ATV) alone, in combination with Carboplatin (CBPT) and with the glycolytic inhibitor PFK158 (PFKi) in ovarian cancer (OC).

Methods: MTT assay and the Chou-Talalay methodology were used to test anticancer activity in vitro; half maximal inhibitory concentration (IC50) and combination index (CI) were calculated. Cellular changes were studied with transmission electron microscopy (TEM). ATV was combined with PFKi as we previously showed that PFKi, in addition to glycolysis, inhibits lipid metabolism by targeting PLA2G3. PLA2G3 expression was studied by western blot given that downregulation in OVCAR8 using two shRNAs (sh33, sh35) induced autophagy, a prodeath condition in OC, and was associated with chemosensitization compared to nontargeted controls (NTC) (unpublished data). A random sample of 10 patient-derived OC xenografts (PDX) was studied by TEM.

Results: OVCAR8 exhibited a dose dependent proliferation inhibition when treated with ATV (IC50 8μM). PFKi and CBPT IC50 were 4μM and 78μM. PFKi treatment combined with 4μM and 8μM of ATV resulted in ATV sensitizing cells to PFKi by shifting PFKi IC50 down to 2.7μM and 0.4μM, respectively. When ATV was combined in constant ratio with CBPT, CIs were >1.1 indicating antagonism. Combination of ATV 4μM with PFKi 2μM resulted in greater decrease in PLA2G3 and p62 and greater increase in cleaved PARP compared to PFKi alone suggesting higher levels of autophagy and apoptosis. ATV and combination treatment resulted in increased caveolin-1 levels, previously shown to be associated with apoptotic cell death. TEM analysis of ATV and PFKi treated cells showed greater number of lipid rich multilamellar bodies (MLB) compared to controls. PLA2G3 knockdowns exhibited higher MBL formation, lower p62, and when treated with statin and with PFKi, cleaved PARP was significantly higher compared to NTCs. TEM showed that PDXs clustered in low and high MLB groups suggesting a distinct novel phenotype.

Conclusions: ATV could enhance PFKi antitumor activity by jointly targeting PLA2G3 leading to metabolic reprogramming of OC. Importantly, ATV antagonized CBPT. Additional studies are in progress to explore the mechanistic pathway of ATV and characterize the significance of MLB in OC as a prodeath phenotype and biomarker of response.

Citation Format: Eleftheria Kalogera, Debarshi Roy, Jamie N. Bakkum-Gamez, William A. Cliby, Sean C. Dowdy, Viji Shridhar. Atorvastatin antagonizes carboplatin, synergizes with the glycolytic inhibitor PFK-158, and induces lipid laden multilamellar bodies in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5821.
Abstract 5829: CDK8 inhibitor SEL120-34A targets CD34 positive AML cells by regulation of various transcriptional programs involved in maintenance of leukemia stem cells
Authors: Majewska Eliza , Mazan Milena , Mikula Michal , Dreas Agnieszka , Wiklik Katarzyna , Golas Aniela , Wojcik Katarzyna , Masiejczyk Magdalena , Statkiewicz Malgorzata , Kuklinska Urszula , Goryca Krzysztof , Grochowska Aleksandra , Cabaj Aleksandra , Combik Michal , Ostrowski Jerzy , Brzozka Krzysztof , Rzymski Tomasz
Published: August 2018

Despite heterogeneity deregulated transcription is one of the universal features of leukemia cells. This has paved the way for the development of active compounds targeting epigenetic and transcriptional factors. A substituted tricyclic benzimidazole, SEL120-34A, is a novel inhibitor of Cyclin-dependent kinase 8 (CDK8), which regulates transcription by associating with the Mediator complex. In many cancer cells SEL120-34A regulates expression of STAT1- dependent genes as a major transcriptional effect. In AML cells regulation of NUP98-HOXA9 - dependent transcription and other transcriptional programs involved in maintenance of leukemia stem cells have been observed as a dominant mechanism of action. Treatment with the compound resulted in a differential efficacy on CD34 positive AML cells with elevated STAT5 S726 levels and stem cell characteristics. In contrast, resistant cells were negative for activated STAT5 and revealed lineage commitment. Prolonged exposure of AML cells lines to chemotherapy led to the enrichment in population of resistant CD34 positive cells, which proved to be oversensitive to SEL120-34A treatment, providing rationale for rational combinations with approved drugs. Further clinical development of SEL120-34A is warranted as a novel therapeutic approach in relapsed and refractory AML.

Citation Format: Eliza Majewska, Milena Mazan, Michal Mikula, Agnieszka Dreas, Katarzyna Wiklik, Aniela Golas, Katarzyna Wojcik, Magdalena Masiejczyk, Malgorzata Statkiewicz, Urszula Kuklinska, Krzysztof Goryca, Aleksandra Grochowska, Aleksandra Cabaj, Michal Combik, Jerzy Ostrowski, Krzysztof Brzozka, Tomasz Rzymski. CDK8 inhibitor SEL120-34A targets CD34 positive AML cells by regulation of various transcriptional programs involved in maintenance of leukemia stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5829.
Abstract 5843: The efficacy of a histone deacetylase inhibitor in combination with a MEK inhibitor in lung cancer cells harboring RAS mutations
Authors: Yamada Tadaaki , Amann Joseph M. , Tanimoto Azusa , Taniguchi Hirokazu , Shukuya Takehito , Yano Seiji , Takayama Koichi , Carbone David P.
Published: August 2018

Purpose: Non-small-cell lung cancer (NSCLC) can be identified by precise molecular subsets based on genomic alterations that drive tumorigenesis and include mutations in EGFR, KRAS, and various ALK fusions. However, despite effective treatment for EGFR and ALK, promising therapeutics have not been developed for patients with KRAS mutations. Therefore, novel therapeutic strategies for KRAS mutated cancer based on molecular mechanisms are needed to improve their prognosis. It has been reported that one way the RAS-ERK pathway contributes to tumorigenesis is by affecting stability and localization of FOXO3a protein, an important regulator of cell death and the cell cycle.

Experimental Design: We used NSCLC cells with RAS mutation to evaluate the effect of a MEK inhibitor in combination with a HDAC inhibitor through the expression and localization of FOXO proteins in vitro and in vivo. Protein expression was examined by Western blotting.

Results: Combined treatment with a MEK inhibitor and a HDAC inhibitor showed synergistic effects on cell viability of RAS mutated lung cancer cells through activation of FOXOs, with a subsequent increase in BIM and cell cycle inhibitors. Moreover, in a mouse xenograft model, the combination of belinostat and trametinib significantly decreases tumor formation through FOXOs by increasing BIM and increase in cell cycle inhibitors p21 and p27.

Conclusions: These findings demonstrate that FOXOs might be one of the critical pathways in RAS driven lung cancer cells, suggesting that the dual molecular targeted therapy for MEK and HDACs may be promising as novel therapeutic strategy in NSCLC with specific populations of RAS mutations.

Citation Format: Tadaaki Yamada, Joseph M. Amann, Azusa Tanimoto, Hirokazu Taniguchi, Takehito Shukuya, Seiji Yano, Koichi Takayama, David P. Carbone. The efficacy of a histone deacetylase inhibitor in combination with a MEK inhibitor in lung cancer cells harboring RAS mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5843.
Abstract 5844: Targeting DNA repair in Philadelphia positive B-ALL
Authors: Johnson Danielle , Tharkar Shwetha , Jones Simon , Jarpe Matt , Chandrasekharan Mahesh , Bhaskara Srividya
Published: August 2018

Introduction: The Philadelphia (Ph) chromosome was the first reported chromosomal rearrangement linked to a human malignancy. Ph-positive precursor B-cell acute lymphoblastic leukemic (Ph+Pre-B-ALL) expressing the BCR-ABL1 oncoprotein is a major subclass of ALL with poor prognosis and high relapse rates in adults. BCR-ABL1 drives an aberrantly hyperactive DNA repair that confers survival advantages to leukemic cells and serves as its ‘Achilles' heel'. We used HDAC1,2 selective inhibitor in isolation or in combination with doxorubicin (a chemotherapy regimen component used for treating pre-B-ALL) to combat the aberrant DSB repair processes.

Experimental design: We used a combination of molecular and cell biology, proteomics and functional genomics-based approaches and primary patient-derived xenograft mouse models to understand the genome stability mechanisms targeted by HDAC1,2 inhibition to overcome oncogenic signals promoted by the BCR-ABL1 fusion protein.

Results: Mass-spectrometry analysis and DNA repair assays showed that HDAC1,2 inhibition and doxorubicin treatments impact common as well as distinct DNA repair and genome maintenance networks including decreased chromatin association of Mre11-Rad51-DNA ligase 1, the central hub of DNA repair. Translating this mechanistic knowledge, we then showed that the HDAC1,2 inhibitor either alone or when combined with a low dose doxorubicin caused cytotoxicity in primary patient Ph+ Pre-B-ALL cells, and decreased leukemia burden without adverse side-effects in vivo in refractory Ph+ Pre-B-ALL PDX models that we created. We recently found that HDAC1,2 targets H4K91ac mark in Ph+Pre-B-ALL cells. H4K91ac occurs within the body of nucleosome core and thus directly controls nucleosome or chromatin integrity. Increased H4K91ac following HDAC1,2 inhibition occurs around DSB sites genome-wide could cause a delay in the rate at which DSBs are repaired in Ph+Pre-B-ALL cells as a result of defective nucleosome structure around DSB sites.

Conclusion: Our comprehensive study using a multipronged approach showed that HDAC1,2 inhibition as a monotherapy or in combination with a low-dose doxorubicin can override DSB repair ‘addiction' in Ph+ Pre-B-ALL. We are currently using the genome-wide ChIP-seq approach and an homing endonuclease DSB reporter system to examine how HDAC1,2 inhibition changes the chromatin landscape in Ph+Pre-B-ALL cells.

Citation Format: Danielle Johnson, Shwetha Tharkar, Simon Jones, Matt Jarpe, Mahesh Chandrasekharan, Srividya Bhaskara. Targeting DNA repair in Philadelphia positive B-ALL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5844.
Abstract 5847: A histone deacetylase inhibitor OBP-801 and eribulin synergistically inhibit the growth with apoptosis in triple-negative breast cancer cells
Authors: Ono Hisako , Sowa Yoshihiro , Iizumi Yosuke , Horinaka Mano , Taguchi Tetsuya , Sakai Toshiyuki
Published: August 2018

Purpose: Triple negative breast cancer (TNBC) is the most aggressive subtype in breast cancer. Eribulin is one of the well-tolerated chemotherapeutic drugs for the treatment of metastatic breast cancer. We usually administer eribulin or eribulin with anti-HER2 antibodies. Eribulin was approved for metastatic breast cancer refractory to anthracyclins and taxanes through EMBRACE trial, and the subgroup analysis indicated the efficacy of eribulin was effective in patients with TNBC. However, the prognosis of patients with TNBC is still poor because of the various molecular characteristics. Therefore, there is an urgent need for more effective treatment for the management of TNBC.

Methods: We investigated the effect of eribulin in several TNBC cell lines. Eribulin inhibited the cell growth of TNBC cells in a dose-dependent manner. However, eribulin increased the expression of survivin, known to inhibit apoptosis. To counteract the up-regulation of survivin by eribulin, we used OBP-801, a novel histone deacetylase (HDAC) inhibitor, because HDAC inhibitors were reported to suppress the expression of survivin.

Results: Co-administration of OBP-801 with eribulin showed a synergistic inhibition of cell growth in TNBC cells. The mechanism of this combination is due to the enhancement of apoptosis. The apoptosis was partially dependent on caspase, and it was via the suppression of not only survivin as expected, but also Bcl-xL. OBP-801 could suppress the survivin expression induced by eribulin at both protein and mRNA level. Interestingly, the combination more potently suppressed a MAPK pathway than each agent.

Conclusion: We found that the combination of eribulin and OBP-801 synergistically inhibits the growth with apoptosis in TNBC cells, raising the possibility that the combination might be a novel promising strategy against TNBC patients.

Citation Format: Hisako Ono, Yoshihiro Sowa, Yosuke Iizumi, Mano Horinaka, Tetsuya Taguchi, Toshiyuki Sakai. A histone deacetylase inhibitor OBP-801 and eribulin synergistically inhibit the growth with apoptosis in triple-negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5847.
Abstract 5850: Nrf2-mediated oxidative stress response is altered during acquired resistance to the proteasome inhibitor, oprozomib, in multiple myeloma
Authors: Gaikwad Snehal M. , Zingone Adriana , Michalowski Aleksandra , Najera Susana , Quintanilla-Artega Anaisa , Gorjifard Sayeh , Simmons John , Watson Nick , Landgren Ola , Huang Jing , Mock Beverly
Published: August 2018

Multiple myeloma (MM) is a hematologic neoplasm characterized by malignant proliferation of plasma cells in the bone marrow. Proteasome inhibitors are widely used in treatment regimens for MM. Although initial responses to PI (e.g., bortezomib, carfilzomib) treatments have been promising, patients often develop resistance and become refractory to disease. Understanding molecular alterations in signaling cascades influenced by proteasome inhibitors and mechanisms underlying acquired resistance is needed. In this study, we have established a clinically relevant oproxomib-resistant subline (KMS28BMONYX) of the MM cell line KMS28BM. The KMS28BMONYX cell line is pan-resistant to PIs with a 10-fold increase in IC50 for oprozomib as compared to the parental line. To identify genes involved in modulating drug resistance, we analyzed gene expression profiles of both parental and resistant cell lines using the Affymetrix GeneChip Human Genome U133 Plus 2.0 array. Ingenuity Pathway Analysis of microarray data comparing the parental and resistant cells revealed an acute dependence on stress response proteins to maintain PI-resistance. Activation of nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2; gene symbol NFE2L2) coupled with elevated levels of sequestosome 1/p62 (SQSTM1/p62) were prominent features of the KMS28BMONYX cell line. Altered levels of SQSTM1 correlated with resistance to oprozomib in several MM cell lines. Simultaneously, the KMS28BMONYX cell line showed increased expression of MYC and MCL1. Oprozomib treatment stabilized c-Myc expression in the KMS28BMONYX line. The Champion ChiP Transcription Factor Search Portal database DECODE predicted two c-Myc transcription factor binding sites in the SQSTM1 promoter. CHIP-seq data for MYC in MM1s cells also indicates strong binding in the promoter region of SQSTM1. Our data suggest that therapies targeting the SQSTM1/p62-Nrf2 pathway may help overcome proteasome inhibitor resistance in refractory MM patients.

Citation Format: Snehal M. Gaikwad, Adriana Zingone, Aleksandra Michalowski, Susana Najera, Anaisa Quintanilla-Artega, Sayeh Gorjifard, John Simmons, Nick Watson, Ola Landgren, Jing Huang, Beverly Mock. Nrf2-mediated oxidative stress response is altered during acquired resistance to the proteasome inhibitor, oprozomib, in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5850.
Abstract 5852: FGF2 confers resistance to novel BET inhibitors in metastatic uveal melanoma
Authors: Chua Vivian , Purwin Timothy , Liao Connie , Aplin Andrew
Published: August 2018

Uveal melanoma (UM) is the most common intraocular malignancy in adults and frequently metastasizes to the liver. Metastatic UM responds poorly to chemotherapy, immunotherapy and MAPK pathway inhibitors; hence, there is an urgent unmet need for new treatment strategies. UM has a low mutational burden and progression is associated with abberrant transcriptional programs. Inhibition of epigenetic modulators involved in transcriptional regulation such as the bromodomain and extraterminal domain (BET) proteins, may be feasible for the treatment of UM. Pre-clinically, JQ1, a first generation BET inhibitor, has been shown to suppress UM growth. Additionally, a multi-site clinical trial is ongoing testing a novel BET inhibitor, PLX51107 (Plexxikon Inc) in metastatic UM patients. Since growth factors in the tumor microenvironment potentially contribute to intrinsic resistance and poor responses to therapies, we determined effects of growth factors on the efficacy of BET inhibitors in metastatic UM cells. We show that FGF2 provides resistance of UM cells to the growth inhibitory effects of BET inhibitors, JQ1, PLX51107 and the third generation inhibitor, PLX72853. FGF2 rescued BET inhibitor-induced apoptosis and cell cycle arrest, which was associated with reversal of the decreased expression of cell cycle regulators (cyclin D1, phospho-RB) and increased expression of pro-apoptotic markers (cleaved PARP, Bim). Importantly, FGF receptor (FGFR) inhibitors reversed FGF2-induced BET inhibitor resistance. As UM predominantly metastasizes to the liver, we investigated FGF2 production by hepatic stellate cells. We show that hepatic stellate cells secrete FGF2 and stellate cell conditioned medium protects metastatic UM cells against the growth inhibitory effects of BET inhibitors. Interestingly, BET inhibitor treatment of UM cells elevated FGFR protein expression and this finding is also shown in UM cell xenograft tumors and in patient tumor samples following PLX51107 treatment. These results indicate that the FGF2/FGFR pathway is activated to promote resistance to BET inhibition via the secretion of FGF2 in the tumor stroma and adaptive upregulation of FGFR expression in UM. In conclusion, our studies suggest that co-targeting of FGFR signaling and BET proteins may be required to maximize the responses of metastatic UM to BET inhibitors.

Citation Format: Vivian Chua, Timothy Purwin, Connie Liao, Andrew Aplin. FGF2 confers resistance to novel BET inhibitors in metastatic uveal melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5852.
Abstract 5868: Preclinical testing of 5-amino-1-((1R,2S,3S,4R)-2,3-dihydroxy-4-methylcyclopentyl)-1H-imidazole-4-carboxamide (ICA-1): A potent protein kinase C-ι inhibitor as a potential anticancer drug
Authors: Apostolatos Christopher , Apostolatos Andre H. , Ratnayake Wishrawana S. , Bourgeois Marie , Acevedo-Duncan Mildred
Published: August 2018

Protein Kinase C iota (PKC-ι) is an oncogene overexpressed in many cancer cells including prostate, breast, ovarian, melanoma and glioma. Previous In- vitro studies have shown that ICA-1 a PKC-ι specific inhibitor, is effective against some cancer cell lines by decreasing cell growth and inducing apoptosis {Pillai et al. Int. J. Biochem. Cell Biol. 43 (2011) 784-794. To assess ICA-1 as a possible therapeutic, In- vivo studies using a murine model were performed. ICA-1 was tested for stability in blood serum and results demonstrated that ICA-1 was stable in human plasma at 25oC and 37oC over a course of two hours. Toxicity of ICA-1 was tested for both acute and sub-acute exposure. The acute exposure showed subject surviving after 48 hours of doses ranging from 5mg/kg to 5000 mg/kg. Sub-acute tests exposed the subjects to 14 days of treatment and was followed by serum and tissue collection. AST, ALK-P, GGT, Troponin, and CR-P serum levels were measured to assess organ function. Heart, liver, kidney, and brain tissues were analyzed for accumulation of ICA-1. Finally athymic nude mice were xenografted with DU-145 prostate cancer cells. After tumors reached approximately 1 cm2, they were either treated with ICA-1 or left as control until the tumor reached 2 cm2. Results showed tumors in treated mice took almost double the time to reach the experimental end point, showing a significant growth reduction. In conclusion, ICA-1 is stable, shows low toxicity, and is a potential therapeutic for some carcinoma tumors.

Citation Format: Christopher Apostolatos, Andre H. Apostolatos, Wishrawana S. Ratnayake, Marie Bourgeois, Mildred Acevedo-Duncan. Preclinical testing of 5-amino-1-((1R,2S,3S,4R)-2,3-dihydroxy-4-methylcyclopentyl)-1H-imidazole-4-carboxamide (ICA-1): A potent protein kinase C-ι inhibitor as a potential anticancer drug [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5868.
Abstract 587: Small solute carrier and sirtuin genes are potential prognostic biomarkers for renal cell carcinoma
Authors: Jordan Andre R. , Mullani Naureen , Talukder Asif , Lokeshwar Vinata B.
Published: August 2018

Introduction: Five-year survival of metastatic renal cell carcinoma (mRCC) patients is < 10% and African American (AA) males have the highest incidence. In the kidney, Small Solute Carrier (SLC) and Sirtuin (SIRT) gene families regulate redox signaling, oxidative stress responses, transport of glycolysis and Krebs cycle metabolites, etc. We examined the prognostic potential of eleven SLC and SIRT genes to predict clinical outcome in RCC patients and evaluated the biological functions of SLC13A3 in RCC cells.

Methods: Expression of SLC (13A3, 22A6, 47A1, 5A10) and SIRT 1-7 transcript levels was evaluated in a TCGA RCC-dataset (n=604 patients). 13A3 expression was measured by quantitative RT-PCR (qPCR) in matched normal and RCC specimens from 53 patients. Biomarker levels were correlated with clinical outcome, using Mann-Whitney test. RCC cells stably-expressing SLC13A3, were examined for proliferation and cell cycle under normoxia and hypoxia.

Results: In the TCGA dataset, SIRT4, SIRT5, SLC22A6, SLC5A10, and SLC47A1 downregulation and SIRT2, SIRT6 and SIRT7 upregulation correlated with higher tumor-stage and metastasis (P< 0.001). Kaplan-Meier plots showed that these biomarkers stratified patients into low- or high-risk for survival (P<0.001). qPCR showed 40-fold downregulation of SLC13A3 expression in RCC tissues when compared to normal kidney (P< 0.0001). Downregulation was 40-fold in White/Hispanic patients, but 198-fold in AA patients (P=0.0049) and correlated with tumor stage and metastasis (P=0.009). SLC13A3 expression in RCC cells increased GSH transport by 2.5-fold and inhibited cell proliferation by 3-4-fold (P<0.001), due to cell-cycle arrest at G1-S or G2-M checkpoints. Treatment of RCC cells with DNA-demethylating agent 5-Azacytidine and Trichostatin A, induced SLC13A3 expression by 50-fold (P<0.001).

Conclusion: SLC/SIRT family members are potential prognostic biomarkers for RCC. This first study on SLC13A3 reveals that it is a potential tumor suppressor and its downregulation in RCC tissues correlates with metastasis and racial disparity.

Citation Format: Andre R. Jordan, Naureen Mullani, Asif Talukder, Vinata B. Lokeshwar. Small solute carrier and sirtuin genes are potential prognostic biomarkers for renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 587.
Abstract 5879: Effect of Minnelide, a prodrug, on cervical cancer growth
Authors: Ramakrishnan Vivek , Giri Bhuwan , Hooda Urvashi , Wilkinson Peter , deHaydu Christopher , Oleas Janneth , Roy Sabita , Ramakrishnan Sundaram , Saluja Ashok
Published: August 2018

Human Papilloma Virus (HPV) infection is associated with the development of Cervical cancer. Therapeutic resistance and recurrence remain the major obstacle to successful treatment of cervical cancer patients. Recently, a novel pro-drug Minnelide, derived from the diterpenoid triepoxide, triptolide, was found to be very effective against several human cancers in experimental animal models. The goal of the present study is to determine the effect of triptolide (in vitro) or Minnelide (in vivo) on HPV positive cervical cancer cells. Triptolide inhibited the proliferation of human cervical cancer cell lines, Ca Ski, SiHa, Me-180, and C-33a with an IC50 of 50 - 100 nM. Furthermore, triptolide inhibited the expression of viral oncoproteins E6 and E7 transcripts significantly. Consequently, p53, tumor suppressor protein levels were increased in the treated cells which led to increased apoptosis and reduced proliferation. Subsequently, we determined the effect of Minnelide on cervical cancer growth in athymic, nude mice. Tumor (SiHa and CaSki) bearing mice were treated with either 0.2 or 0.4 ug/kg doses of Minnelide. These studies showed that Minnelide inhibited tumor growth by about 70 % when compared to control group of mice and improved survival significantly. In a parallel study, combination treatment with carboplatin and Minnelide showed more than additive inhibition of tumor growth. In summary, Minnelide treatment reduced the transcript levels of HPV oncoproteins and inhibited cellular proliferation by upregulating p53. Our studies further demonstrate that Minnelide can be used either as a monotherapy or in combination with platinum drugs to inhibit the growth of cervical cancers.

Citation Format: Vivek Ramakrishnan, Bhuwan Giri, Urvashi Hooda, Peter Wilkinson, Christopher deHaydu, Janneth Oleas, Sabita Roy, Sundaram Ramakrishnan, Ashok Saluja. Effect of Minnelide, a prodrug, on cervical cancer growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5879.
Abstract 5886: Translational reprogramming of breast cancer and its role in tamoxifen resistance
Authors: Bakogianni Sofia , Geter Phillip , Ernlund Amanda , Arju Rezina , Gadi Abhilash , Schneider Robert J.
Published: August 2018

Breast cancer is the most commonly diagnosed malignancy among women in the U.S. and the second leading cause of cancer-related deaths in women. The estrogen receptor-positive (ER+) breast cancer subtype comprises the majority (70-80%) of breast cancer cases and the majority of late recurrences. Anti-estrogen therapy with tamoxifen remains a cornerstone of adjuvant therapy for ER+ breast cancers in the premenopausal setting, but resistance is inevitable for a third of patients, leading to metastatic disease, which is responsible for the majority of breast cancer deaths. Our work demonstrates that tamoxifen resistance in ER+ breast cancer involves selective mRNA translation mediated by hyperactivation of mTOR and MNK1, two kinases that play major roles in mRNA translation. The hyperactivation of mTOR and MNK1 converges on eukaryotic translation initiation factor 4E (eIF4E) to increase its availability and mRNA selectivity. Using tamoxifen-sensitive and -resistant ER+ cells, we conducted genome-wide transcriptomic and translatomic analyses +/- silencing of eIF4E. We identified key genes responsible for tamoxifen resistance, whose mRNAs are selectively translationally upregulated with increased levels of eIF4E. RUNX2 is a key mRNA that is selectively translationally upregulated, which we show provides resistance by opposing estrogenic signaling and possibly phenotypically reprogramming the cell. Silencing of RUNX2 strongly resensitizes the cells to tamoxifen. We also show that RUNX2 impairs cellular proliferation and cell survival of previously drug-resistant cells in the presence of tamoxifen. Silencing of key translationally upregulated mRNAs, such as RUNX2, can partially restore endocrine therapy sensitivity. Using a tamoxifen-resistant ER+ PDX model, and patient-derived sensitive and resistant tumor tissues (no recurrence or recurrence within 5 years), we validated the hyperactivation of mTOR and MNK1, the overexpression of eIF4E, and selective mRNA translation in tamoxifen resistance. We hypothesize that selection for increased expression of RUNX2 and other selectively translated mRNAs promotes a more “basal-like,” estrogen-independent phenotype. We aim to determine how tamoxifen resistance translationally reprograms breast cancer cells to a different breast cancer phenotype (e.g., cancer stem cell-like, basal-like, luminal with disrupted ER signaling).

Citation Format: Sofia Bakogianni, Phillip Geter, Amanda Ernlund, Rezina Arju, Abhilash Gadi, Robert J. Schneider. Translational reprogramming of breast cancer and its role in tamoxifen resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5886.
Abstract 5890: Aurora-A potentiates chemoresistance via regulating the microRNA biogenesis pathway
Authors: Lin Li Jyuan
Published: August 2018

Chemotherapy has a good success rate in colorectal cancer; however, recurrence of colorectal cancer is still frequent due to the development of drug resistance. MicroRNA (miRNA) is a type of non-coding RNA with a size of around 19-22 nucleotides and plays an important role in regulating many biological functions, the onset of diseases, as well as drug response. It was reported that Dicer, one of the key enzymes of the miRNA biogenesis pathway, may be involved in the chemoresistance through regulating the expression of miRNAs. Aurora-A, a cell cycle-regulated kinase, plays a vital role in cancer development and chemoresistance. According to the TCGA database, the expression levels of Dicer and Aurora-A are both increased in colorectal cancer. Here, we demonstrated that overexpressed Aurora-A can regulate the chemodrug response by influencing the miRNA biogenesis pathway via Dicer in colorectal cancer. Our results showed that the protein level, but not the mRNA expression, of Dicer was decreased upon 5-FU or oxaliplatin treatment in drug sensitive cells; whereas, the expression level of Dicer was increased in oxaliplatin resistant cell lines. Knockdown expression of Dicer in oxaliplatin resistant cell lines could reverse the resistance of oxaliplatin. The expression levels of several potential miRNAs changed upon chemodrugs treatment. Interestingly, we found that overexpressed Aurora-A could increase the expression of Dicer and potentiate drug resistance in colorectal cancer cells. In contrast, knockdown expression of Aurora-A decreased Dicer protein expression and led to enhanced drug sensitivity. Taken together, our results suggested that Aurora-A and Dicer can collaborate to regulate drug response through influencing the miRNA biogenesis pathway in colorectal cancer. The further mechanism of Dicer and Aurora-A in chemoresistance is currently under our investigation.

Citation Format: Li Jyuan Lin. Aurora-A potentiates chemoresistance via regulating the microRNA biogenesis pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5890.
Abstract 5895: Targeting RhoA-regulated gene transcription in drug-resistant melanoma
Authors: Misek Sean A. , Gallo Kathleen A. , Neubig Richard R.
Published: August 2018

Much of the recent focus of melanoma targeted therapy has been on the ERK pathway, which is aberrantly activated in approximately 90% of melanoma tumors. Over half of these express BRAFV600E. Current targeted therapies such as Vemurafenib (BRAFV600E inhibitor), or a combination therapy of BRAF + MEK inhibitors show profound initial effects in a majority of BRAFV600E expressing tumors. However, these responses are often short-lived and resistance typically develops within months. The goal of this work is to identify pharmacologically targetable resistance mechanisms so that effective combination therapies can be developed.

Preliminary bioinformatics analysis suggests that the RhoA subfamily of Rho GTPases is activated in BRAFi-resistant cancer cell lines and BRAFi/MEKi-resistant human melanoma tumors. Thus, we hypothesize that RhoA promotes BRAFi resistance, so simultaneously targeting RhoA and BRAF may reverse drug resistance. Using cell line models of acquired BRAFi-resistance we demonstrated that the RhoA pathway is activated in a subset of resistant cell lines. The cell lines with increased RhoA activation have increased sensitivity to multiple ROCK inhibitors.

In addition to regulating the cytoskeleton, RhoA can also regulate gene transcription through activation of multiple transcriptional co-activators, including MRTF and YAP. MRTF and YAP regulated gene transcription through their role as transcriptional co-activators and their interaction with chromatin remodeling complexes. MRTF and YAP are both activated in BRAFi-resistant cell lines. Indirectly targeting MRTF with CCG-222740 or YAP with the YES1 inhibitor Dasatinib effectively kills BRAFi-resistant melanoma cells.

Sox10 was previously identified as a gene which promotes BRAFi resistance. Expression of Sox10 is downregulated, and Sox9 is upregulated, 100-1000-fold exclusively in the resistant cell lines which have RhoA activation. Further, a Sox10 gene signature is inversely correlated with a RhoA/C signature in the TCGA dataset and melanoma scRNA-seq data. Sox10 loss is a major drug resistance melanoma in melanoma. These data suggest that targeting RhoA-regulated gene transcription may be an effective mechanism to target Sox9High/Sox10Low cells, and ultimately prevent or reverse drug resistance.

Taken together these data suggest that MRTF and YAP promote Vemurafenib resistance in Sox9High/Sox10Low melanoma cells.

Citation Format: Sean A. Misek, Kathleen A. Gallo, Richard R. Neubig. Targeting RhoA-regulated gene transcription in drug-resistant melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5895.
Abstract 5898: A systems approach for determining the mechanism of resistance to tumor treating fields in glioblastoma
Authors: Chen Dongjiang , Le Son , Thomas Nagheme , Tran David D.
Published: August 2018

Glioblastoma (GBM) is the most common and deadliest malignant brain cancer in adults despite aggressive chemoradiotherapy. Recently, Tumor Treating Fields (TTFields) was approved in combination with adjuvant temozolomide chemotherapy for newly diagnosed GBM. The addition of TTFields resulted in a significant improvement in overall survival. TTFields are low-intensity alternating electric fields that are thought to disturb mitotic macromolecules' assembly, leading to disrupted chromosomal segregation and cell death. However, the majority of GBM are not sensitive to TTFields and most of TTFields responders eventually develop resistance. However the mechanism of resistance remains largely unexplored. Understanding how cancer cells gain the ability to circumvent the biophysical forces of TTFields and their downstream effects will provide new opportunities to improve therapeutic efficacy of this novel anti-cancer treatment modality. To accomplish these objectives, we have developed several human GBM cell lines that demonstrated relative resistance to the cytotoxic effects of TTFields compared to the parental cells. Importantly TTFields-induced chromosomal instability such as the formation of micronuclei was unchanged in resistant cells compared to their sensitive counterparts, suggesting that resistance to TTFields may be conferred by a selective loss of deleterious downstream reactions to the biophysical damages. To systematically identify the mechanism of resistance, we have recently developed two innovative computational platforms, GeneRep and nSCORE and experimentally validated them in several published datasets. The tandem platforms complemented each other and allowed us to 1) interrogate large-scale gene expression profiles of pairs of TTFields resistant cells vs. sensitive counterparts to extract candidate resistance-specific gene regulatory networks, and 2) functionally rank specific core factors responsible for resistance, respectively. Once identified, biological confirmation of these factors using cell lines, mouse models and samples of patient's derived TTFields sensitive and resistant GBM. Our long-term goal is to develop targeted therapy to prevent tumor's resistance to TTFields therapy.

Citation Format: Dongjiang Chen, Son Le, Nagheme Thomas, David D. Tran. A systems approach for determining the mechanism of resistance to tumor treating fields in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5898.
Abstract 5899: Genome-wide CRISPR-Cas9 screening identifies genetic vulnerabilities and potential therapeutic targets in castration resistant prostate cancer
Authors: Haldrup Jakob , Schmidt Linnéa , Pedersen Jakob S. , Sørensen Karina D.
Published: August 2018

Background: Treatment options for castration-resistant prostate cancer (CRPC) are limited and only a few agents (e.g. enzalutamide, docetaxel) are routinely used in the clinic. Unfortunately, CRPC tumors will invariable develop resistance to these agents and only a subset of patients will respond. Thus, novel predictive biomarkers are urgently needed to ensure that an expensive and potentially harmful agent is given only to patients who will benefit from it. Furthermore, to enable new treatment strategies, a better understanding of drug resistance mechanisms is required.

Methods: To identify novel drug resistance genes and mechanisms of therapy resistance, we performed genome-wide CRISPR-Cas9 knockout screens in LNCaP (hormone naïve) and in the isogenic C4 (castration resistant) PC cell line, respectively. Using 77,441 unique sgRNAs (Brunello library), a total of 19,114 protein-coding genes were tested for their potential functional role in enzalutamide or docetaxel resistance. Both IC50 and IC90 values were used for selection. MAGeCK was used to identify enriched and depleted sgRNAs (treatment vs. DMSO).

Results: Among the highest ranked hits for the C4 dropout screens, several potential genetic vulnerabilities and mechanisms of resistance were identified, as knockout of specific genes sensitized C4 cells to enzalutamide. None of these hits were observed in LNCaP, which suggest CRPC-specific resistance mechanisms. For the positive screens, increased enzalutamide resistance was observed after knockout of genes encoding e.g. phosphokinases and specific solute carriers (SLCs) for C4 and LNCaP, respectively. Lastly, our results suggest that knockout of specific zinc finger nucleases (ZFNs), posttranslational modification enzymes or microtubule components may modulate docetaxel resistance in C4 cells.

Conclusion: Drug resistance is a major clinical problem. Here, we identified genetic vulnerabilities that may be translated into predictive biomarkers, combination therapies and/or novel drug development strategies for CRPC.

Citation Format: Jakob Haldrup, Linnéa Schmidt, Jakob S. Pedersen, Karina D. Sørensen. Genome-wide CRISPR-Cas9 screening identifies genetic vulnerabilities and potential therapeutic targets in castration resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5899.