Targeting RAD51-BRCA2 Interaction to Enhance Synthetic Lethality with Olaparib in Pancreatic Cancer: Development of a Novel Phenyl Furan-Quinoline-Carboxylic Acid Series.

A variety of inflammatory cytokines have been demonstrated to participate in tumorigenesis and progression. Secretory leukocyte protease inhibitor (SLPI) has been demonstrated to show a broad-spectrum of anti-inflammatory effects. This study investigates the expression of SLPI in human pancreatic cancer tissues and cells as well as its biological effects in human pancreatic cancer cells. Reverse transcription-polymerase chain reaction, immunohistochemistry, and Western blot were used to detect SLPI mRNA and protein levels in human pancreatic cancer tissues, adjacent tissues, and pancreatic cancer Bxpc-3 and Panc-1 cells. Knockout of SLPI expression was established by recombinant viral vector expressing short hairpin RNA (shRNA) targeting SLPI. Cell viability was analyzed by MTT assay. Cell apoptosis was detected by Hochest33258 staining and flow cytometry assay. Higher SLPI expression was observed in pancreatic tissues, Bxpc-3 cells, and Panc-1 cells compared to the peritumoral tissues (p < 0.01). SLPI expression in Bxpc-3 and Panc-1 cells was effectively silenced by shRNA (p < 0.001). Silencing of SLPI expression significantly reduced cell viability, inhibited cell proliferation, and induced cell apoptosis (p < 0.001). Abnormal over-expression of SLPI in pancreatic cancer cells may be associated with the development of disease through its roles in promoting cancer cell survival and proliferation as well as anti-apoptosis. SLPI can be used as a target for developing targeted therapy of pancreatic cancer.

Desmoplasia of Pancreatic Ductal Adenocarcinoma

Background: GPRC5A is an orphan G-protein coupled receptor acting as an oncogene in some cancers and as a tumor suppressor in other. Its role in pancreatic cancer has not been studied systematically. ELAV-like protein 1, also known as “HuR,” is an RNA binding protein that is encoded by the ELAVL1 gene. HuR post-transcriptionally regulates multiple genes, plays key roles in human malignancies, and is known to mediate the efficacy of gemcitabine. Our preliminary data indicated that, in pancreatic cells, GPRC5A transcription responded to gemcitabine treatment and that its mRNA likely interacted with HuR. Methods: We immunohistochemically analyzed GPRC5A protein expression in primary and metastatic pancreatic cancer samples. We examined the effects of GPRC5A on pancreatic cells’ ability to proliferate, migrate, and invade, and how gemcitabine modulates this ability. We also studied the interaction between GPRC5A and HuR and examined how it is affected by gemcitabine. Lastly, we used microarray expression analyses to identify the genes and pathways linked to GPRC5A in pancreatic cancer cells. Results: We analyzed public mRNA expression data from 675 human cancer cell lines and 10,609 samples from The Cancer Genome Atlas (TCGA): GPRC5A mRNA abundance in pancreatic cancer was the highest (cell lines) or second highest (TCGA) among all tissues and cancer types. We analyzed an independent set of 252 pancreatic normal and cancer samples: we found GPRC5A mRNA to be up-regulated in primary tumor samples compared to normal pancreas, and even further up-regulated in metastatic pancreatic cancer. We immunostained 208 cores (103 primary and metastatic pancreatic cancer samples): we found GPRC5A protein to be barely expressed in normal pancreatic ductal cells and highly expressed in both primary and metastatic pancreatic ductal cancer cells. We carried out in vitro studies of multiple pancreatic cancer cell lines: we found that increasing GPRC5A protein levels promoted pancreatic cancer cell growth and migration whereas siRNA-mediated knockdown of GPRC5A impaired proliferation and invasion. We found that gemcitabine treatment enhanced GPRC5A expression in pancreatic cancer cells. Conversely, siRNA-mediated knockdown of GPRC5A sensitized the cells to gemcitabine. We showed that HuR/ELAVL1 up-regulated GPRC5A protein in the first 18 hours following gemcitabine treatment by stabilizing GPRC5A’s mRNA through binding to at least on site in GPRC5A’s 3´UTR. Microarray analysis showed that GPRC5A overexpression impacts several signaling networks. Conclusions: Our results indicate that GPRC5A acts as an oncogene in pancreatic cancer. Unexpectedly, gemcitabine was found to increase GPRC5A's mRNA and protein levels. We showed that this increase is mediated by HuR, a known enabler of gemcitabine efficacy, through a direct interaction between HuR and GPRC5A’s mRNA. It appears that the sensitivity of pancreatic cancer cells to gemcitabine can be augmented through down-regulation of GPRC5A. Citation Format: Honglei Zhou, Aristeidis Telonis, Yi Jing, Masaya Jimbo, Fernando Blanco, Eric Londin, Jonathan Brody, Isidore Rigoutsos.{Authors}. GPRC5A acts as a potent oncogene in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A41.

NADPH oxidase (NOX)-derived reactive oxygen species (ROS) contribute significantly to inflammation-associated carcinogenesis. Expression of dual oxidase 2 (Duox2), one of seven members of the NOX gene family, is up-regulated in inflammatory bowel disease, chronic pancreatitis, and in many human malignancies including carcinomas of the prostate, lung, and breast. Previously, we demonstrated that Stat1 and/or NF-κB play a critical role in modulating the enhanced expression of Duox2, and its cognate maturation factor DuoxA2, by IFN-γ and lipopolysaccharide in human pancreatic cancer cells. This cytokine-mediated increase in Duox2 expression is responsible for a consequent significant increase in tumor cell H2O2 production and DNA damage. Using Caco2 and T84 human colon cancer lines, and BxPC-3 pancreatic cancer cells, we now report that two other pro-inflammatory cytokines, IL-4 and IL-13, also strongly induce Duox2/DuoxA2 RNA and protein expression (&amp;gt;5-10-fold after 24h treatment with 50 ng/ml cytokine). In the BxPC-3 line, IL-4 exposure activates the Stat6 signaling pathway, enhances expression of Duox2/DuoxA2 in a time- and concentration-dependent manner, and leads to a significant increase in the generation of extracellular H2O2. The transcription and translation inhibitors actinomycin D and cyclohexamide both individually suppress IL-4-induced Duox2 expression, suggesting that IL-4-mediated Duox2 up-regulation is transcriptionally regulated, but that new protein synthesis is also necessary. We found that Stat6 is essential for IL-4-induced Duox2 expression because silencing Stat6 with Stat6-specific siRNA significantly attenuates IL-4-induced Duox2 RNA and protein levels in BxPC-3 cells. To evaluate the potential role of Duox2 in inflammation-associated human cancers further, immunohistochemical studies were performed to semi-quantitatively examine Duox expression using human pancreatic and colon cancer tissue arrays. We found that a majority of samples of pancreatic intra-epithelial neoplasia and frank pancreatic cancer demonstrated high-level expression of Duox , often in association with inflammatory cell infiltrates; high-level Duox expression was also found in most colorectal cancer samples. These studies, in concert with our previous experiments, strongly suggest that ROS, produced as a consequence of cytokine-induced Duox up-regulation, may be associated with the development of inflammation-related gastrointestinal malignancies. Note: This abstract was not presented at the meeting. Citation Format: Yongzhong Wu, James H. Doroshow. IL-4/IL-13 induce Duox2/DuoxA2 expression and reactive oxygen production in human pancreatic and colon cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5358. doi:10.1158/1538-7445.AM2014-5358

Objective: Silibinin is a flavonoid with antihepatotoxic properties, and exhibits pleiotropic anticancer effects. However, the molecular mechanisms responsible for its anticancer actions in pancreatic cancer cells, and the effects on such cells and normal pancreatic cells, remain unclear. The objective of this study was to determine the effect of silibinin on human pancreatic cancer cells and normal ductal cells. Methods: Human pancreatic cancer cells (MIA PaCa-2 and PANC-1) and normal ductal cells (hTERT-HPNE) were cultured with 0-400 μM silibinin for 48 h. Thereafter, the proliferation, invasion, apoptosis, and signaling pathways of the pancreatic cells were evaluated. Results: Silibinin significantly inhibited the proliferation, invasion, and spheroid formation of human pancreatic cancer cells in vitro in a dosedependent manner (p&lt;0.05). It also induced apoptosis in a dose-dependent manner. Western blot analysis showed that silibinin downregulated extracellular signaling-regulated kinase (ERK) and serine/threonine protein kinase (AKT) in human pancreatic cancer cells. It also upregulated microtubule associated protein 1 light chain 3 β (LC3B) and cleaved caspase-3 via c-Jun N-terminal kinases (JNK) signaling. On the other hand, silibinin increased the mRNA and protein levels of c-Jun, Twist-related protein 1, and Snail. It also decreased exogenous p53 levels, but increased endogenous c-Jun protein levels in human pancreatic cancer cells. However, silibinin did not affect cell viability and endogenous c-Jun levels in pancreatic normal ductal cells. It increased exogenous p53 levels, but decreased stemness-related gene expression in pancreatic normal ductal cells. Silibinin increased Ki-67 levels in pancreatic cancer cells, but decreased them in pancreatic normal ductal cells. Conclusion: Silibinin not only exerted anticancer effects by inhibiting AKTERK and JNK signaling, but also upregulated cancer stemness-related genes in human pancreatic cancer cells. These results suggest that silibinin should be used as a therapeutic agent for human pancreatic cancer with caution.

Background: Therapeutic options for advanced stage pancreatic cancer are limited. Patients harboring germline BRCA mutations benefit from PARP inhibitors (PARPi); unfortunately, such mutations are rare in pancreatic cancer. Tumor Treating Fields (TTFields), electric fields that disrupt cellular processes crucial for cancer cell viability, have shown effectiveness against pancreatic cancer cells, and are currently under clinical investigation for the treatment of patients with pancreatic cancer. The mechanism of action of TTFields in various cancer types has suggested involvement of BRCA downregulation. The current study examined the potential sensitization of BRCA wild-type pancreatic cancer cell lines to PARPi with TTFields application. Methods: BxPC3 and AsPC1 human pancreatic BRCA wild-type cancer cells were treated for 72 h with TTFields (frequency of 150 kHz; intensity of 1 and 0.5 V/cm RMS, respectively), using the inovitro device. The PARPi niraparib and olaparib were each administered to the cells at various concentrations, with or without co-application of TTFields. At treatment cessation, cell count, colony formation, and apoptosis were measured. Results: Applying PARPi to pancreatic cell lines yielded a dose-dependent cytotoxic and anti-clonogenic effects, and induced apoptosis. TTFields application also induced such effects when applied alone, while delivery of TTFields together with PARPi amplified the effects demonstrated by PARPi alone. Conclusions: Concomitant application of TTFields and PARPi in BRCA wild type pancreatic cancer cells exhibits a potential improvement relative to the mono-therapies. This could be rationalized based on the previously demonstrated ability of TTFields to induce a state of BRCAness in cancer cells, and suggests benefit for TTFields and PARPi co-treatment in the absence of background BRCA mutations. Citation Format: Hila Ene, Kerem Ben Meir, Antonia Martinez-Conde, Roni Frechtel-Gerzi, Hila Gabay, Daria Gerasimova, Rotem Engelman, Eyal Dor-On, Adi Haber, Moshe Giladi, Yoram Palti. Treatment of pancreatic cancer cells with tumor treating fields (TTFields) and PARP inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7134.

Recently, cancer stem cells have been reported as a new therapeutic target in pancreatic cancer as well as other cancers, but the specific role of these cells is unknown. The authors investigated the functional roles of CD133+ cells, 1 of the putative cancer stem cell candidates in pancreatic cancer. CD133 expression was assessed in human pancreatic cancer and cancer cell lines by quantitative real-time reverse transcriptase polymerase chain reaction and flow cytometry. Next, they compared the ability of CD133+ and CD133- cells to proliferate, migrate, and invade using 2 pancreatic cancer cell lines. In particular, they evaluated the relationship between CD133+ cells and primary pancreatic stromal cells. CD133 was expressed in primary human pancreatic cancer tissues and some cancer cell lines, whereas there was little expression in primary normal pancreatic epithelial cells and primary pancreatic stromal cells. CD133+ cells, isolated by flow cytometry, showed increased cell proliferation under anchorage-independent conditions (P<.01), and enhanced migration and invasion, particularly when cocultured with primary pancreatic stromal cells (P<.001). Chemokine-related receptor-4 (CXCR4), markedly overexpressed in CD133+ cells, may be responsible for the increased invasive ability of the cells cocultured with pancreatic stromal cells, which express stromal derived factor-1, the ligand to CXCR4. These data suggest that CD133+ cells exhibit more aggressive behavior, such as increased cell proliferation, migration, and invasion, especially in the presence of pancreatic stromal cells. The targeting therapy for the interaction between CD133+ cancer cells and stromal cells may be a new approach for the treatment of pancreatic cancer.

To investigate the regulation of tight junction molecules in normal human pancreatic duct epithelial (HPDE) cells and pancreatic cancer cells, we introduced the human telomerase reverse transcriptase (hTERT) gene into HPDE cells in primary culture and compared them to pancreatic cancer cell lines. The hTERT-transfected HPDE cells were positive for PDE markers and expressed claudin-1, claudin-4, claudin-7, and claudin-18, occludin, tricellulin, marvelD3, JAM-A, zonula occludens (ZO)-1, and ZO-2. The tight junction molecules, including claudin-4 and claudin-18 of normal HPDE cells, were in part regulated via a protein kinase C signal pathway by transcriptional control. In addition, claudin-18 in normal HPDE cells and pancreatic cancer cells was markedly induced by a PKC activator, and claudin-18 in pancreatic cancer cells was also modified by DNA methylation. In the marvel family of normal HPDE cells and pancreatic cancer cells, tricellulin was upregulated via a c-Jun N-terminal kinase pathway, and marvelD3 was downregulated during Snail-induced epithelial-mesenchymal transition.

Pancreatic cancer is the third leading cause of cancer-related death in the United States, and deeper understanding into factors that control its progression will be key to developing future treatments. Previously, we showed that Bmi1 is required for the initiation of pancreatic cancer in mice, and enhances growth of pancreatic cancer cells in vitro. However, the role of Bmi1 in established tumors and the mechanisms underlying its requirement have so far been elusive. To investigate this, we used a CRISPR/Cas9 strategy to delete BMI1 in primary cell lines derived from human pancreatic tumors as well as murine pancreatic cancer cell lines, and created clonal lines lacking BMI1 expression. We then used subcutaneous tumor growth models as well as transcriptomic and metabolomic profiling to define the role of BMI1 expression in tumor growth. BMI1 knockdown in human and mouse pancreatic cancer cells resulted in slower growth in vitro and in vivo compared to controls. Histologically, control tumors were moderately differentiated, while BMI1-/- tumors were small or histologically undetectable. BMI1-/- tumors with sufficient tumor tissue displayed prominent extracellular mucin pools, with few cancer cell clusters interspersed within mucin and dead cell debris. Interestingly, the remaining cancer cells in the BMI1-/- tumors, identified by CK19 immunostaining, still expressed phosphorylated ERK, indicating MAPK pathway activation, as expected in Kras mutant cells. Thus, BMI1 expression was required for the growth of both human and murine pancreatic cancer cells. Given this, we sought to determine the functional processes regulated by BMI1 to facilitate pancreatic cancer growth by using both transcriptomic and metabolomic comparison of WT or BMI1-/- human pancreatic cancer cells. Further analysis revealed changes in pathways with known importance in pancreatic cancer, including many related to metabolism and cell proliferation. Strikingly, the expression of every enzyme in the glycolytic pathway was downregulated in BMI1-/- cells. Loss of BMI1 also resulted in changes in pathways that control cell proliferation, and specifically the G2/M checkpoint, possibly explaining the growth defect observed in vitro and in vivo. Together, our data show that BMI1 is a key regulator of essential cellular processes for human and mouse pancreatic cancer growth, including metabolism and cell cycle progression. Further study will be required to determine the exact mechanism of BMI1 regulation of these pathways, as well as its potential as a therapeutic target in pancreatic cancer. Citation Format: Heather K. Schofield, Christopher J. Halbrook, Annachiara Del Vecchio, Donovan Drouillard, Zeribe C Nwosu, Joyce K. Thompson, Carlos Espinoza, Yaqing Zhang, Costas A Lyssiotis, Marina Pasca di Magliano, Filip Bednar. BMI1 is required for human and murine pancreatic cancer progression and controls metabolism and cell proliferation [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-025.

Objective: To explore the expression of long non-coding RNA-LINC01410 in the pancreatic cancer tissues, corresponding paracancerous tissues, human pancreatic cancer cell lines and normal pancreatic ductal epithelial cell line, and analyze the effect of LINC01410 on pancreatic cancer cell proliferation and migration. Methods: Real-time fluorescent quantitative PCR (RT-qPCR) was used to detect the expression level of LINC01410 in 16 cases of pancreatic cancer tissue and its adjacent tissues. RT-qPCR was performed to analyze LINC01410 expression in the pancreatic cancer cell lines AsPC-1, CAPAN-1, SW1990, BxPC-3 and CFPAC-1, and human normal pancreatic ductal epithelial cell line HPDE6-C7. Transfection of interference plasmid (shRNA) in the pancreatic cancer cell line with the highest expression level of LINC01410 were used to knock-down the expression of LINC01410. CCK-8 assay, colony formation assay, and transwell chamber assay were performed to detect the proliferation and migration of pancreatic cancer cells. The complementary paired miRNAs and downstream genes of LINC01410 were predicted by bioinformatics. The expression of miRNA and downstream genes was detected by RT-qPCR, and the protein expression of downstream genes was determined by Western blot. Results: The expression of LINC01410 in the pancreatic cancer tissues was significantly higher than that in the adjacent tissues [(3.46±0.32) vs (0.65±0.08), P<0.01]. The expression levels of LINC01410 in the pancreatic cancer cell lines were significantly higher than that in the normal human pancreatic ductal epithelial cells (P<0.05). The expression of LINC01410 was highest in BxPC-3 cells (P<0.01). After knock-down of the LINC01410 expression in the pancreatic cancer cell line BxPC-3, the cell proliferation was significantly inhibited (P<0.05), and the cell migration ability was decreased (P<0.05). LINC01410 complementarily paired with miR-497-5p, and miR-497-5p complementarily paired with IFITM3. After inhibiting the expression of LINC01410, the expression of miR-497-5p was increased [(1.04±0.17) vs (5.79±0.43), P<0.01], the mRNA expression of IFITM3 was decreased [(0.39±0.05) vs (1.00±0.03), P<0.01], and the protein expression of IFITM3, CDK6, Cyclin D2, PCNA, Vimentin, and N-cadherin was decreased. Conclusions: The expression of LINC01410 was increased in pancreatic cancer tissues and cell lines. Down-regulation of LINC01410 expression inhibits the proliferation and migration of pancreatic cancer BxPC-3 cells, and its mechanism may be closely related to regulating the miR-497-5p and IFITM3 gene expression.

753 Background: Pancreatic cancer remains one of the most aggressive malignancies, frequently diagnosed at the locally advanced or metastatic stage. In the advanced setting, first-line chemotherapy options include gemcitabine with nab-paclitaxel or FOLFIRINOX, a combination regimen of fluorouracil, oxaliplatin, irinotecan and leucovorin. The FOLFIRINOX regimen is however associated with greater toxicity and is hence used only in patients with good performance status. BRCA-mutated tumors seem to be more sensitive to FOLFIRINOX due to the DNA-damaging, platinum-based component of this treatment regimen. Tumor Treating Fields (TTFields) are electric fields that disrupt cellular processes crucial for cancer cell viability that have shown efficacy in preclinical pancreatic cancer models; and, in various cancer types, have been shown to reduce expression of proteins from the BRCA-dependent DNA repair pathway. The current study examined the potential use of TTFields for sensitization of BRCA wild-type pancreatic cancer cells to treatment with FOLFIRINOX. Methods: Human pancreatic BRCA wild-type cancer cells BxPC3 and AsPC1 were treated with TTFields (150 kHz; 0.7 and 1 V/cm RMS, respectively), using the inovitro device. FOLFIRINOX was administered to the cells at increasing concentrations, with or without co-treatment with TTFields. After 72h of treatment, cell count, colony formation, and apoptosis were measured. For mechanistical insight, gene and protein expression were evaluated following 24, 48, or 72h of TTFields treatment. Results: TTFields application to the pancreatic cells together with FOLFIRINOX elevated the cytotoxic, clonogenic and apoptotic effects induced by FOLFIRINOX or TTFields alone. RNA sequencing data revealed that TTFields downregulated DNA damage repair, DNA replication, and cell cycle related processes. Specifically, real-time PCR and Western blot analysis demonstrated reduced expression of several central players in the BRCA DNA damage repair pathway. Conclusions: TTFields application together with FOLFIRINOX in pancreatic cancer cells lacking background BRCA mutations exhibits potential improvement relative to FOLFIRINOX alone, that may be rationalized based on downregulation of key DNA repair pathways. Future studies should explore the possibility of reducing FOLFIRINOX treatment dose, potentially alleviating FOLFIRINOX-related toxicity.

Objective To explore microRNA- 138- 5p(miR- 138- 5p) expression in pancreatic cancer and its effects on pancreatic cancer cell migration and invasion,and its mechanism. Methods Quantitative real- time polymerase chain reaction(FQ- PCR)was used to examine the expression of miR- 138- 5p in pancreatic cancer cell lines and primary carcinoma tissues from human patients.Lentiviral vector containing miR- 138- 5p mimics(lv- miR- 138- m),or miR- 138- 5p inhibitor(lv- miR- 138- i)was used to either up- regulate or down- regulate miR- 138- 5p in PANC- 1 cells, respectively.MiR- 138- 5p impact on PANC- 1 cell line migration and invasion abilities by wound- healing and Transwell cell invasion assay. The predicted targeting of miR- 138- 5p on vimentin was acknowledged by a dual luciferase assay. Results Expression of miR- 138- 5p in 8 pancreatic cancer cell lines were 1 to 10 times lower than in normal pancreatic cells, expression in pancreatic cancer tissue than in adjacent low 52.99±10.62 times.Lv - miR- 138- m significantly inhibited the migration and invasion of PANC- 1 cells capability, compared with the negative control group were lower 1.27±0.03, 4.96±1.16 times. Lv- miR- 138- i can significantly enhance their migration and invasive ability, compared with the negative control group, respectively 3.23±0.71, 3.40±0.66 times. MiR- 138- 5p and vimentin (VIM)3'untranslated region(3'UTR)region may be complementary binding,inhibition of expression can reduce the invasiveness effect VIM promote cell lv- miR- 138- i induced, suggesting miR- 138- 5p at least in part through inhibition of pancreatic regulation play VIM cancer cell invasion role. Conclusion MiR- 138- 5p play an important role in pancreatic cancer cell migration and invasion and it directly targeting regulate the VIM inhibit pancreatic cancer cell invasion, which may be one of the mechanisms which play an inhibition of pancreatic cancer cell invasion. Key words: Pancreatic cancer; MicroRNA; Migration; Invasion; Vimentin

Background: FOLFIRINOX is a first-line chemotherapy treatment for patients with advanced pancreatic cancer and good performance status. This combination regimen of fluorouracil, oxaliplatin, irinotecan and leucovorin seems to be more effective in BRCA-mutated tumors due to the platinum-based component, acting by the induction of DNA damage. Tumor treating fields (TTFields) are electric fields that disrupt cellular processes crucial for cancer cell viability. TTFields have shown efficacy in preclinical pancreatic cancer models, and to reduce expression of proteins from the BRCA-dependent DNA repair pathway in various cancer types. The current study examined the potential use of TTFields to sensitize BRCA wild-type pancreatic cancer cells to treatment with FOLFIRINOX. Methods: Human pancreatic BRCA wild-type cancer cells BxPC3 and AsPC1 were treated with TTFields, using the inovitro device (Frequency: 150 kHz; Intensity: 0.7 V/cm RMS for BxPC3 cells; 1 V/cm RMS for AsPC1 cells). FOLFIRINOX was administered to the cells at increasing concentrations, with or without co-treatment with TTFields. After 72h of treatment, cell count, colony formation, and apoptosis were measured. For mechanistical insight, RNA was isolated from TTFields-treated and control samples following 24- and 48-hours treatment and examined by RNA-sequencing and real-time PCR. Additionally, protein was isolated from 72-hours treated samples and examined by Western blot. Results: TTFields application to the pancreatic cells together with FOLFIRINOX reduced cell count and colony formation and induced apoptosis relative to FOLFIRINOX or TTFields alone. TTFields downregulated DNA damage repair, DNA replication, and cell cycle related processes, with reduced expression of several central players in the BRCA DNA damage repair pathway. Conclusions: Application of TTFields together with FOLFIRINOX exhibits potential improvement relative to FOLFIRINOX alone in treatment of pancreatic cancer cells lacking background BRCA mutations. This outcome may be rationalized based on downregulation of key DNA repair pathways. Citation Format: Hila Ene, Kerem Ben Meir, Hila Gabay, Rotem Engelman, Eyal Dor-On, Adi Haber, Moshe Giladi, Yoram Palti. Tumor treating fields (TTFields) sensitize BRCA wild type pancreatic cancer cells to treatment with FOLFIRINOX [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1691.

The subcellular localization and biochemical characteristics of blood group A antigen were studied by immunogold methods and by SDS-PAGE and Western blotting procedures in N-nitrosobis)2-oxopropyl)amine (BOP)-induced pancreatic cancer (PC) in Syrian hamsters, in the pancreatic cancer cell line (PC-1) derived from a primary induced pancreatic cancer, and in intrapancreatic and subcutaneous transplants of PC-1 cells. Normal hamster duodenal epithelial cells expressing A antigen were compared with the normal hamster pancreas (lacking A antigen), human PC tissues from patients with blood group A and human PC cell lines. Blood group A antigen was present on the membrane of hamster duodenal cells, but was absent in the normal pancreatic cells. A antigen was localized mainly on the cell membrane of the hamster cancer cells both in vivo and in vitro. Glycoproteins with blood group A specificity were observed by SDS-PAGE and Western blotting procedures in the membrane fraction of PC-1 cells, with a major component of molecular mass of approximately 120 kd. Similar migration patterns were observed in the primary induced PC and in subcutaneous and intrapancreatic transplants of PC-1 cells. Membrane preparations from cell lines derived from two primary pancreatic cancers from patients of blood group A and from human pancreatic cell lines, CD11 and CD18, showed a major A reactive component with a molecular mass similar to that found in the hamster PC cells. These findings suggest that: (i) both the hamster and human PC cells in vitro produce glycoproteins with blood group A specificity of similar molecular masses; (ii) differences exist in the structure of the glycoprotein immunoreactive with the anti-A antigen between the normal and cancerous cells; and (iii) differences exist in the molecular mass of the anti-A reactive substance between hamsters and human PC cells and between tissues in vivo and in vitro.

125: Protein Kinase Cβ Inhibition Induces Radiosensitization in Pancreatic Cancer