Murray, Nicole R.

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal human malignancies due to its silent clinical onset, rapid progression, and limited responsiveness to current treatment options. These features underscore the urgent need for early detection strategies and for new molecular targets that can be exploited therapeutically. Epithelial Cell Transforming Sequence 2 (ECT2) is a Rho family guanine nucleotide exchange factor that was originally identified as an oncoprotein and later shown to regulate cytokinesis. In this study, we examined the clinical relevance of ECT2 expression in PDAC and determined its functional contribution to transformed growth and tumorigenicity. Our analyses revealed that ECT2 expression increases at the earliest stages of PDAC development, remains persistently elevated during disease progression, and associates with reduced overall patient survival. Furthermore, a substantial fraction of ECT2 is aberrantly localized to the cytoplasm of PDAC cells. Functional studies demonstrated that depletion of ECT2 suppresses three-dimensional growth, invasive behavior, and tumor formation in vivo, while having little impact on PDAC cell cytokinesis. Mechanistically, we found that ECT2 is required for activation of Rac1 and RhoA and downstream MEK/ERK and ROCK signaling, respectively. Consistent with these results, analyses of PDAC patient datasets revealed a strong positive association between ECT2 expression and Rho GTPase as well as MEK/ERK and ROCK pathway signatures. Together, our data identify ECT2 as an early driver of PDAC transformation and highlight it as a promising therapeutic target. Citation Format: Dania Al-Qasrawi, Nayya N. Murray, Ryan A. Argo, Alicia K. Fleming Martinez, Prita Pandya, Anaya Y. Clarke, Kayla C. Winter, Murli Krishna, Peter Storz, Nicole R. Murray, Verline Justilien, . The Rho-GEF ECT2 links Rho GTPases to MEK/ERK pathway activation in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5993.

Objectives: This trial served as a proof-of-concept for whether inhibition of protein kinase C iota (PKCι) with auranofin and sirolimus provide antineoplastic effects in patients with recurrent high-grade serous ovarian cancer. Methods: This drug combination was administered to patients with recurrent high-grade serous ovarian cancer. Dosing was based on unpublished phase 1 data and consisted of auranofin 6 mg and sirolimus 5 mg both orally per day of a 28-day cycle. The primary endpoint was tumor response. Available tumor tissue was assessed for PKCι protein expression by immunohistochemistry (IHC) and PRKCI copy number by fluorescence in-situ hybridization (FISH) after the start of cancer therapy. Results: Twenty-two patients were enrolled, and 21 were evaluable for all clinical trial endpoints. One patient was unevaluable because she did not receive a full chemotherapy cycle. No tumor responses were seen in the first 21 patients, resulting in early trial termination per a priori trial design. The median progression-free survival was 2.1 months (95% CI: 1.8-3.7). The median overall survival was 4.4 months (95% CI: 2.6-12.5). Fourteen (67%) patients had at least one grade 3 or worse adverse event. Nineteen of 21 evaluable patients had available tumor tissue, which showed the median PKCι copy number averaged per cell of 3 (range: 2 to 7), and PKCι expression (at least 1+) in all. Conclusions: As prescribed here, auranofin and sirolimus manifested no antineoplastic activity in patients with recurrent high-grade serous ovarian cancer that expressed PKCι.

Abstract Lung squamous cell carcinoma (LUSC) is a major histological subtype of lung cancer accounting for ~30% of all lung cancer diagnoses. LUSC patients suffer from poor therapeutic response, high relapse rate, and poor prognosis. A major reason for this bleak outcome is the lack of well characterized oncogenic drivers of LUSC. This has stalled the generation of relevant genetic pre-clinical mouse models amenable to studying LUSC tumorigenesis in vivo and developing targeted therapeutics to treat LUSC patients. Our group has identified concomitant 3q26 copy number gain (CNG) and TP53 loss as defining genetic alterations present in ~90% of LUSC tumors. Furthermore, we have identified three 3q26 oncogenes (PRKCI, ECT2 and SOX2) that genetically and biochemically collaborate to drive LUSC tumor formation. Coordinate overexpression of Prkci, Ect2 and Sox2, and loss of Trp53 in ex vivo cultures of lung basal stem cells (LBSCs; a potential cell of origin for LUSC) is both necessary and sufficient to transform these cells into orthotopic LUSC tumors in syngeneic mice. These findings indicate that 3q26 amplification and TP53 loss play a critical role in the initiation and progression of LUSC. Based on these data, we have developed the first autochthonous genetically engineered mouse model (GEMM) to study the role of 3q26 CNG in LUSC tumorigenesis in vivo. Our GEMM allows inducible overexpression of Prkci, Ect2, and Sox2 and knockout of Trp53 (PES/Trp53−/−) in lung tissue. Tumorigenesis will be initiated in PES/Trp53−/− mice using an established protocol to target transgene recombination to LBSCs in vivo. These mice will be assessed for tumor latency, survival, tumor burden, and metastatic potential. In related studies, we used bioinformatics analyses on primary LUSC tumors from the Cancer Genome Atlas’ database to identify 13 genes in addition to PRKCI, ECT2 and SOX2, whose expression is driven by 3q26 amplification. These genes were functionally characterized by assessing the effect of shRNA-mediated gene silencing on soft-agar growth of human H520 LUSC cells, a cell line that harbors 3q26 amplification. Our results revealed that knockdown of each of these genes independently resulted in a significant decrease in soft agar colony formation. We further assessed these genes through RT-qPCR mRNA expression profiling comparing PES/Trp53−/- transformed LBSCs to non-transformed LBSCs. These genes were significantly upregulated in PES/Trp53−/- transformed LBSCs, suggesting that they play important roles in LBSC transformation. Future work will further assess the molecular mechanisms by which these additional 3q26 genes contribute to LUSC cell transformation and assess the role of alternate cells of origin (Club and AT2) in 3q26-driven LUSC tumor formation using our PES/Trp53−/− GEMM. Citation Format: Kayleah M. Meneses, Capella Weems, Yi Liu, Verline Justilien, Nicole R. Murray, Alan P. Fields. Characterizing 3q26 copy number gain in lung squamous cell carcinoma through a novel genetically engineered mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 27.

Lung adenocarcinoma (LUAD) is the most prevalent form of non–small cell lung cancer (NSCLC) and a leading cause of cancer death. Immune checkpoint inhibitors (ICIs) of programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) signaling induce tumor regressions in a subset of LUAD, but many LUAD tumors exhibit resistance to ICI therapy. Here, we identified Prkci as a major determinant of response to ICI in a syngeneic mouse model of oncogenic mutant Kras / Trp53 loss (KP)–driven LUAD. Protein kinase Cι (PKCι)–dependent KP tumors exhibited resistance to anti–PD-1 antibody therapy (α-PD-1), whereas KP tumors in which Prkci was genetically deleted (KPI tumors) were highly responsive. Prkci- dependent resistance to α-PD-1 was characterized by enhanced infiltration of myeloid-derived suppressor cells (MDSCs) and decreased infiltration of CD8 + T cells in response to α-PD-1. Mechanistically, Prkci regulated YAP1-dependent expression of Cxcl5 , which served to attract MDSCs to KP tumors. The PKCι inhibitor auranofin inhibited KP tumor growth and sensitized these tumors to α-PD-1, whereas expression of either Prkci or its downstream effector Cxcl5 in KPI tumors induced intratumoral infiltration of MDSCs and resistance to α-PD-1. PRKCI expression in tumors of patients with LUAD correlated with genomic signatures indicative of high YAP1-mediated transcription, elevated MDSC infiltration and low CD8 + T cell infiltration, and with elevated CXCL5 / 6 expression. Last, PKCι-YAP1 signaling was a biomarker associated with poor response to ICI in patients with LUAD. Our data indicate that immunosuppressive PKCι-YAP1-CXCL5 signaling is a key determinant of response to ICI, and pharmacologic inhibition of PKCι may improve therapeutic response to ICI in patients with LUAD.

Protein kinase C iota (PKCι) functions as a bonafide human oncogene in lung and ovarian cancer and is required for KrasG12D-mediated lung cancer initiation and progression. PKCι expression is required for pancreatic cancer cell growth and maintenance of the transformed phenotype; however, nothing is known about the role of PKCι in pancreas development or pancreatic tumorigenesis. In this study, we investigated the effect of pancreas-specific ablation of PKCι expression on pancreatic cellular homeostasis, susceptibility to pancreatitis, and KrasG12D-mediated pancreatic cancer development. Knockout of pancreatic Prkci significantly increased pancreatic immune cell infiltration, acinar cell DNA damage, and apoptosis, but reduced sensitivity to caerulein-induced pancreatitis. Prkci-ablated pancreatic acinar cells exhibited P62 aggregation and a loss of autophagic vesicles. Loss of pancreatic Prkci promoted KrasG12D-mediated pancreatic intraepithelial neoplasia formation but blocked progression to adenocarcinoma, consistent with disruption of autophagy. Our results reveal a novel promotive role for PKCι in pancreatic epithelial cell autophagy and pancreatic cancer progression.

Abstract In glioblastoma (GBM), invasion and proliferation are reciprocally related—e.g., targeting one stimulates the other. Thus, effective therapy for GBM requires finding targets that drive both invasion and proliferation and which are druggable, ideally with FDA approved therapeutics. We find that the atypical protein kinase C isoform, PKCi meets these criteria. Using a human GBM tissue microarray, we find that PKCi protein expression fits a bimodal distribution, with >35% of GBMs showing high levels of PKCi expression. Genetic deletion of Prkci, the gene encoding mouse PKCi, impairs tumor invasion and proliferation both in vitro and in vivo, and significantly prolongs survival in an immunocompetent PDGF-driven orthotopic mouse model of GBM. PKCi can be selectively targeted with Auranofin, a small molecule PKCi inhibitor that has been FDA approved for treatment of inflammatory diseases. Like genetic deletion of Prkci Auranofin treatment significantly prolongs survival in our murine GBM model, and does so to a similar degree. Interestingly, analysis of a panel of human and murine GBM cells reveals that sensitivity to Auranofin inhibition of transformed growth directly correlates with expression of PKCi, indicating that PKCi expression profiling could serve as a predictive biomarker for responsiveness to Auranofin. However, genetically deleting or pharmacologically inactivating PKCi does not permanently arrest tumor growth, implying that GBM cells acquire mechanisms that allow them to compensate for the loss of this important signaling molecule. We are currently examining potential “escape” mechanisms through ‘omics-based approaches, which may enable us to enhance the therapeutic potential of Auranofin. Taken together, our results demonstrate that PKCi is a compelling therapeutic target for treatment of GBM that deserves further investigation.

Abstract Pancreatic cancer is the fourth leading cause of cancer death in the United States with current 5-year survival rates at 6%. Greater than 90% of all pancreatic cancers harbor an activating mutation in codon 12 of the Kras gene (KrasG12D). Protein Kinase C iota (PKCι) has been shown to mediate KrasG12D downstream signaling and acinar-to-ductal metaplasia in an explant model of pancreatic cancer initiation. Additionally, inhibition of PKCι in human pancreatic cancer cells leads to decreased tumor size, angiogenesis, and metastasis in an orthotopic tumor model, suggesting that PKCι plays a role in maintaining the oncogenic phenotype of pancreatic cancer cells. We sought to test the hypothesis that PKCι plays a role development and maintenance of pancreatic cancer using a mouse model of KrasG12D-induced pancreatic cancer. Purpose: To identify the effect of PKCι loss on pancreas function and development of KrasG12D-induced pancreatic cancer. Procedures: Pancreata from mice with pancreas-specific deletion of PKCι, with and without pancreas-specific KrasG12D expression, were analyzed for histological and protein expression alterations. Acinar cells isolated from these transgenic mouse models were subjected to in vitro analyses to determine the role of PKCι in pancreatic cell homeostasis. Results: Mice lacking pancreatic PKCι survived and developed normally. Pancreatic knockout of PKCι expression resulted in a phenotype consistent with a defect in autophagic flux. In vitro analyses of isolated acinar cells supported the hypothesis that PKCι promotes autophagy in pancreatic cells. Autophagy exhibits a dual functionality in pancreatic cancer, acting as a tumor suppressor in normal cells and a tumor promoter in established tumor cells. We sought to determine the effect of PKCι knock-out on both of these cell types in a mouse model of pancreatic cancer. Using the LSL mouse model of K-ras induced pancreatic cancer, we demonstrated that pancreatic loss of PKCι lead to an increase in the number of Pancreatic Intraepithelial (PanIN) lesions formed in young mice. However, these lesions were protected from progressing past the early PanIN1/2 stage such that no mice lacking PKCι developed cancer, even after 1.5 years of age. By contrast, over 50% of mice with wild-type PKCι developed cancer; of those without cancer, many had progressed to the PanIN-3 stage, a stage representative of carcinoma in-situ. These data are similar to that seen in mouse models of pancreatic cancer with genetic inhibition of autophagy. Analysis of PanINs in these mice revealed that those lacking PKCι expressed significantly more P62 protein, a selective autophagy substrate, compared to PanINs with wild-type PKCι, supporting a block in the autophagic flux. These data suggest that PKCι plays an important role in both the initiation and progression of pancreatic cancer, possibly by regulating autophagic flux. Impact: Inhibition of pancreatic PKCι expression prevented progression of PanIN lesions past the early PanIN1/2 stage, resulting in a complete block in cancer development in mouse models of pancreatic cancer. Our preliminary data suggests that PKCι promotes cancer progression by regulating autophagic flux, a process that has been shown to be essential for KrasG12D-mediated pancreatic cancers. Pancreatic cancer is characterized by resistance to current therapies. Novel targets for new and more effective therapies are critical to improve outcomes for patients with this deadly disease. Inhibitors of PKCι are currently in clinical trials for ovarian and lung cancers. Our data supports the feasibility of using PKCι inhibitors for therapy in pancreatic cancer. Citation Format: Kristin S. Inman, Amanda A. Francis, Nicole R. Murray. PKCι in pancreatic cancer development: A possible role for autophagy. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A02.