Therapeutic Target In Pancreatic Adenocarcinoma Research Articles

Genetic and immune identification and functional analysis of TRPM8 as a potential biomarker for pancreatic adenocarcinoma proliferation.

Pancreatic adenocarcinoma (PAAD), a member of highly lethal malignant tumors, has a poor outcome and extremely poor prognosis. The transient receptor potential (TRP) superfamily, a group of nonselective cation channels, is capable of influencing cellular functions by regulating calcium homeostasis. In addition, it has been shown that TRP channels can also affect various cellular phenotypes by regulating gene transcription levels and are involved in the development of a variety of malignant tumors. In order to find new therapeutic targets and biomarkers to improve the clinical prognosis of pancreatic cancer, we performed genetic and immunological characterization of TRP channels in PAAD, as well as related functional and prognostic analyses. We investigated the expression, genetic alterations, methylation levels, and immune infiltration levels of TRP channels in PAAD, and further also analyzed the function of TRP channels in PAAD and their prognostic value for PAAD patients. Our results suggest that TRPM8 may contribute to tumor proliferation by controlling the PI3K-AKT-mTOR signaling pathway in PAAD. After careful evaluation of the accumulated data, we concluded that TRPM8 has potential as a prognostic indicator and prospective therapeutic target in PAAD.

Integrated analysis identifies cuproptosis-related gene DLAT and its competing endogenous RNAs network to predict the prognosis of pancreatic adenocarcinoma patients.

Pancreatic adenocarcinoma (PAAD) is a highly malignant tumor with poor prognosis. However, the relationship between cuproptosis-related genes (CRGs) and its competing endogenous RNA (ceRNA) network with the prognosis of PAAD patients remains unclear. To investigate this relationship, we calculated the difference in CRGs between PAAD tissues and normal tissues using the 'limma' R package. Additionally, we employed least absolute shrinkage and selection operator (LASSO) Cox regression analysis to construct a prognostic signature for CRGs. Survival analysis of patients with PAAD was performed using Kaplan-Meier analysis. Furthermore, we used bioinformatics tools to screen for CRGs-related MicroRNA (miRNA) and lncRNAs. To validate these findings, we conducted real-time quantitative polymerase chain reaction (RT-qPCR), CCK-8, colony formation, and Transwell assays to assess the effect of DLAT in vitro. Our results revealed a cuproptosis-related prognostic signature consisting of 3 prognostic genes (DLAT, LIAS, and LIPT1). Notably, patients with a high-risk score for the CRGs signature exhibited poor prognosis in terms of overall survival (OS) (P < .05). The receiver operating characteristic (ROC) curve was used to evaluate the prognostic signature of CRGs. The results showed that the 1-year, 3-year, and 5-year area under the curve values for predicting OS were 0.62, 0.66, and 0.79, respectively. Additionally, the CRGs-related ceRNA network revealed the regulatory axis of LINC00857/has-miR-1179/DLAT in PAAD. In vitro experiments demonstrated that knockdown of LINC00857 and DLAT inhibited the growth and invasion of PAAD cells. This study identified a CRG-related prognostic signature consisting of 3 biomarkers (DLAT, LIAS, and LIPT1) for PAAD. Furthermore, ceRNA network analysis suggested the involvement of the LINC00857/has-miR-1179/DLAT axis in the development of PAAD. Overall, this study provides theoretical support for the investigation of diagnostic and prognostic biomarkers as well as potential therapeutic targets in PAAD.

The potential use and experimental validation of genomic instability-related lncRNA in pancreatic carcinoma.

This study explored the potential role of long noncoding RNA (lncRNAs) associated with genomic instability in the diagnosis and treatment of pancreatic adenocarcinoma (PAAD). Transcriptome and single-nucleotide variation data of PAAD samples were downloaded from the cancer genome atlas database to explore genomic instability-associated lncRNAs. We constructed a genomic instability-associated lncRNA prognostic signature. Then gene ontology and Kyoto encyclopedia of genes and genomes enrichment analyses were used to explore the physiological role of lncRNAs involved in genomic instability. Tumor microenvironments, immunotherapy response, immune cell infiltration, immune checkpoint, and drug sensitivity were compared between high-risk and low-risk groups. In vitro experiments were performed for external validation. Six lncRNAs associated with genomic instability were identified, capable of predicting the prognosis of PAAD. Patients were assigned to low-risk or high-risk groups using these biomarkers, with better or worse prognosis, respectively. The tumor immune score, immune cell infiltration, and efficacy of immunotherapy were worse in the high-risk group. A drug sensitivity analysis revealed the high- and low-risk groups had different half-maximal inhibitory concentrations. The expression of cancer susceptibility candidate 8 was significantly higher in tumor tissues than in normal tissues, while the expression of LYPLAL1-AS1 exhibited an opposite pattern. They may be potential diagnostic or prognostic biomarkers for patients with pancreatic cancer. Genomic instability-associated lncRNAs were explored in this study and predicted the prognosis of PAAD and stratified patients risk in PAAD. These lncRNAs also predicted the efficacy of immunotherapy and potential therapeutic targets in PAAD.

Long Non-Coding RNAs and Metabolic Rewiring in Pancreatic Cancer.

Pancreatic adenocarcinoma is a highly aggressive disease with a poor prognosis. The reprogramming of energetic metabolism has long been implicated in pancreatic tumorigenesis and/or resistance to treatment. Considering that long non-coding RNA dysregulation has been described both in cancerogenesis and in the altered homeostasis of several metabolic pathways, metabolism-associated lncRNAs can contribute to pancreatic cancer evolution. The objective of this review is to assess the burden of lncRNA dysregulation in pancreatic cancer metabolic reprogramming, and its effect on this tumor's natural course and response to treatment. Therefore, we reviewed the available literature to assess whether metabolism-associated lncRNAs have been found to be differentially expressed in pancreatic cancer, as well as whether experimental evidence of their role in such pathways can be demonstrated. Specifically, we provide a comprehensive overview of lncRNAs that are implicated in hypoxia-related pathways, as well as in the reprogramming of autophagy, lipid metabolism, and amino acid metabolism. Our review gathers background material for further research on possible applications of metabolism-associated lncRNAs as diagnostic/prognostic biomarkers and/or as potential therapeutic targets in pancreatic adenocarcinoma.

Retraction Note: EphA2: a determinant of malignant cellular behavior and a potential therapeutic target in pancreatic adenocarcinoma.

Retraction Note: EphA2: a determinant of malignant cellular behavior and a potential therapeutic target in pancreatic adenocarcinoma.

High expression of RNF169 is associated with poor prognosis in pancreatic adenocarcinoma by regulating tumour immune infiltration.

Background: Pancreatic adenocarcinoma (PAAD) is a highly deadly and aggressive tumour with a poor prognosis. However, the prognostic value of RNF169 and its related mechanisms in PAAD have not been elucidated. In this study, we aimed to explore prognosis-related genes, especially RNF169 in PAAD and to identify novel potential prognostic predictors of PAAD. Methods: The GEPIA and UALCAN databases were used to investigate the expression and prognostic value of RNF169 in PAAD. The correlation between RNF169 expression and immune infiltration was determined by using TIMER and TISIDB. Correlation analysis with starBase was performed to identify a potential regulatory axis of lncRNA-miRNA-RNF169. Results: The data showed that the level of RNF169 mRNA expression in PAAD tissues was higher than that in normal tissues. High RNF169 expression was correlated with poor prognosis in PAAD. In addition, analysis with the TISIDB and TIMER databases revealed that RNF169 expression was positively correlated with tumour immune infiltration in PAAD. Correlation analysis suggested that the long non-coding RNA (lncRNA) AL049555.1 and the microRNA (miRNA) hsa-miR-324-5p were involved in the expression of RNF169, composing a potential regulatory axis to control the progression of PAAD. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that RNF169 plays a role in PAAD through pathways such as TNF, Hippo, JAK-STAT and Toll-like receptor signaling. Conclusion: In summary, the upregulation of RNF169 expression mediated by ncRNAs might influence immune cell infiltration in the microenvironment; thus, it can be used as a prognostic biomarker and a potential therapeutic target in PAAD.

Abstract PO-091: Histamine receptor 1 (HRH1): A potentially novel G protein-coupled receptor (GPCR) therapeutic target in pancreatic adenocarcinoma (PDAC) cells and tumors

Abstract A recent study reported that patients taking HRH1 antihistamines have decreased progression of various tumors, including PDAC; the authors inferred that this was an immune effect (Fritz et al., PMID: 33550204). We have initiated studies to test an alternative hypothesis: HRH1 expressed by PDAC cells may contribute to the malignant phenotype and if so, FDA-approved HRH1 antihistamines might be therapeutics to treat or perhaps prevent PDAC. We have undertaken bioinformatic and experimental approaches to test this hypothesis. Our bioinformatic analysis revealed that PDAC tumors in The Cancer Genome Atlas (TCGA) have &amp;gt;30-fold higher HRH1 expression than in normal pancreas (GTEx database) and is highly expressed in PDAC cell lines in the Cancer Cell Line Encyclopedia (CCLE). HRH1 expression was selectively associated with markers of PDAC cells and not with markers of other cell types in the tumor microenvironment. Higher expression of HRH1 in TCGA-PDAC tumors negatively impacts on patient survival. Our experimental studies indicate that human and mouse PDAC cells express HRH1 mRNA, protein and signaling and that HRH1 is present on the surface of PDAC cells. We found that histamine prominently increases calcium [Ca2+] in multiple human PDAC cell lines with EC50 values comparable to that in other cell types. The histamine-stimulated increase in [Ca2+] occurs via a Gq/11 (heterotrimeric GTP binding protein)-dependent mechanism and is blocked by multiple FDA-approved HRH1 antihistamines (with pKi values similar to those of HRH1 inhibition of other cell types). HRH1 activation by histamine increases PDAC cell migration. Histamine also increases the production of numerous cytokines (including VEGF) from PDAC cells, and in preliminary studies, stimulates growth of multiple PDAC cell lines at low concentrations (1-10 nM). Together with published data indicating that mast cells (which synthesize and release histamine) in PDAC tumors are associated with PDAC cell growth/invasion, angiogenesis and worse prognosis, our findings suggest that independent of immune cells, a "mast cell-histamine-PDAC cell HRH1 axis" may contribute to the malignant phenotype of PDAC tumors. Importantly, HRH1 on PDAC cells could be targeted by repurposing approved HRH1 antihistamines as a novel therapeutic approach for PDAC tumors. Supported by grants from the University of California Cancer Research Coordinating Committee and Tobacco-Related Disease Research Program. Citation Format: Cristina Salmeron, Krishna Sriram, Mehrak Javadi-Paydar, Paul A. Insel. Histamine receptor 1 (HRH1): A potentially novel G protein-coupled receptor (GPCR) therapeutic target in pancreatic adenocarcinoma (PDAC) cells and tumors [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-091.

Expression and prognostic impact of FZDs in pancreatic adenocarcinoma

BackgroundDespite the high number of researches on pancreatic adenocarcinoma (PAAD) over past decades, little progress had been made due to lack of effective treatment regimens. We aimed to investigate the expression level, mutation, and clinical significance of the Frizzled (FZD) family in PAAD so as to establish a sufficient scientific evidence for clinical decisions and risk management.MethodsPAAD samples were extracted from The Cancer Genome Atlas (TCGA). Oncomine, Gene expression profiling interactive analysis (GEPIA), human protein atlas (HPA), Kaplan–Meier Plotter, cBioPortal, LinkedOmics, DAVID database, and R software (× 64 3.6.2) were used to comprehensively analyze the roles of FZDs. p value below to 0.05 was considered as significant difference.ResultsIn total, 179 PAAD tissues and 171 paracancerous tissues were included. The expression levels of FZD1, 2, 6, 7, and 8 were higher in PAAD tissues than those in normal pancreatic tissue. The higher the expression levels of FZD2 and FZD7, the higher the clinical stage. The overall survival (OS) time was significantly different between low FZD3, 4, 5, 6, and 9 expression group and high expression group. Multivariable analysis showed that FZD3 and FZD6 were independent prognostic factors. The recurrence free survival (RFS) time was significantly different between low FZD4 and FZD8 expression group and high expression group. The RFS difference between low FZD6 expression group and high expression group had not reached statistical significance (p = 0.067), which might be due to the small sample size. However, multivariable analysis showed that FZD6 was the only independent factor for RFS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that FZDs played a critical role in the Wnt signaling pathway, which was further confirmation that FZDs were transmembrane receptors of Wnt signaling pathway.ConclusionsOur results strongly indicated a crucial role of the FZD family in PAAD. FZD3 and FZD6 could be potential prognostic and predictive markers, and FZD6 might also function as a potential therapeutic target in PAAD by blocking Wnt/β-catenin pathway.

Deciphering the cellular source of tumor relapse identifies CD44 as a major therapeutic target in pancreatic adenocarcinoma.

It has been commonly found that in patients presenting Pancreatic Ductal Adenocarcinoma (PDAC), after a period of satisfactory response to standard treatments, the tumor becomes non-responsive and patient death quickly follows. This phenomenon is mainly due to the rapid and uncontrolled development of the residual tumor. The origin and biological characteristics of residual tumor cells in PDAC still remain unclear. In this work, using PDACs from patients, preserved as xenografts in nude mice, we demonstrated that a residual PDAC tumor originated from a small number of CD44+ cells present in the tumor. During PDAC relapse, proliferating CD44+ cells decrease expression of ZEB1, while overexpressing the MUC1 protein, and gain morphological and biological characteristics of differentiation. Also, we report that CD44+ cells, in primary and residual PDAC tumors, are part of a heterogeneous population, which includes variable numbers of CD133+ and EpCAM+ cells. We confirmed the propagation of CD44+ cells in samples from cases of human relapse, following standard PDAC treatment. Finally, using systemic administration of anti-CD44 antibodies in vivo, we demonstrated that CD44 is an efficient therapeutic target for treating tumor relapse, but not primary PDAC tumors. We conclude that CD44+ cells generate the relapsing tumor and, as such, are themselves promising therapeutic targets for treating patients with recurrent PDAC.

Subtype-Specific MEK-PI3 Kinase Feedback as a Therapeutic Target in Pancreatic Adenocarcinoma

Mutations in the KRAS oncogene are dominant features in pancreatic ductal adenocarcinoma (PDA). Because KRAS itself is considered "undruggable," targeting pathways downstream of KRAS are being explored as a rational therapeutic strategy. We investigated the consequences of MAP-ERK kinase (MEK) inhibition in a large PDA cell line panel. Inhibition of MEK activated phosphoinositide 3-kinase in an EGF receptor (EGFR)-dependent fashion and combinations of MEK and EGFR inhibitors synergistically induced apoptosis. This combinatorial effect was observed in the epithelial but not mesenchymal subtype of PDA. RNA expression analysis revealed predictors of susceptibility to the combination, including E-cadherin, HER3, and the miR200-family of microRNAs, whereas expression of the transcription factor ZEB1 was associated with resistance to the drug combination. Knockdown of HER3 in epithelial-type and ZEB1 in mesenchymal-type PDA cell lines resulted in sensitization to the combination of MEK and EGFR inhibitors. Thus, our findings suggest a new, subtype-specific, and personalized therapeutic strategy for pancreatic cancer.

Genome profiling of pancreatic adenocarcinoma

Pancreatic adenocarcinoma is one of the most aggressive human cancers. It displays many different chromosomal abnormalities and mutations. By using 244 K high-resolution array-comparative genomic hybridization (aCGH) we studied the genome alterations of 39 fine-needle aspirations from pancreatic adenocarcinoma and eight human adenocarcinoma pancreatic cell lines. Using both visual inspection and GISTIC analysis, recurrent losses were observed on 1p, 3p, 4p, 6, 8p, 9, 10, 11q, 15q, 17, 18, 19p, 20p, 21, and 22 and comprised several known or suspected tumor suppressor genes such as ARHGEF10, ARID1A, CDKN2A/B, FHIT, PTEN, RB1, RUNX1-3, SMAD4, STK11/LKB1, TP53, and TUSC3. Heterozygous deletion of the 1p35-p36 chromosomal region was identified in one-third of the tumors and three of the cell lines. This region, commonly deleted in human cancers, contains several tumor suppressor genes including ARID1A and RUNX3. We identified frequent genetic gains on chromosome arms 1q, 3q, 5p, 6p, 7q, 8q, 12q, 15q, 18q, 19q, and 20q. Amplifications were observed in 16 tumors. AKT2, CCND3, CDK4, FOXA2, GATA6, MDM2, MYC, and SMURF1 genes were gained or amplified. The most obvious amplification was located at 18q11.2 and targeted the GATA6 gene, which plays a predominant role in the initial specification of the pancreas and in pancreatic cell type differentiation. In conclusion, we have identified novel biomarkers and potential therapeutic targets in pancreatic adenocarcinoma.

Transient receptor potential channel TRPM8 is over-expressed and required for cellular proliferation in pancreatic adenocarcinoma

The roles of transient receptor potential (TRP) cation channels in pancreatic tumorigenesis are essentially unknown. Here, we focus on the TRP melastatin-subfamily (TRPM) members. Expression of the thermally regulated transmembrane Ca 2+-permeable channel TRPM8 is consistently up-regulated in human pancreatic adenocarcinoma cell lines and tissues. TRPM8-deficient pancreatic cancer cells have reduced ability of proliferation and cell cycle progression with elevated levels of cyclin-dependent kinase inhibitors. These results indicate that TRPM8 is aberrantly over-expressed in pancreatic adenocarcinoma and required for cellular proliferation, and they support further investigation of the potential of TRPM8 as a clinical biomarker and therapeutic target in pancreatic adenocarcinoma.

High mobility group A: A novel biomarker and therapeutic target in pancreatic adenocarcinoma

High mobility group A1 (HMGA1) proteins are architectural transcriptional factors that are over-expressed in a wide range of human malignancies. Recently published evidence suggests HMGA1 is a promising candidate biomarker and therapeutic target in pancreatic cancer. This review summarises data implicating HMGA1 as an important mediator of progression in human cancer and in pancreatic cancer.

High mobility group AT‐hook 1 (HMGA1) is an independent prognostic factor and novel therapeutic target in pancreatic adenocarcinoma

High mobility group AT-hook 1 (HMGA1) proteins are architectural transcription factors that are overexpressed by pancreatic adenocarcinomas. The authors hypothesized that tumor HMGA1 status represents a novel prognostic marker in pancreatic adenocarcinoma. They also tested the hypothesis that HMGA1 promotes anchorage-independent cellular proliferation and in vivo tumorigenicity. Tumor HMGA1 expression was examined by immunohistochemical analysis of tissues from 89 consecutive patients who underwent resection for pancreatic adenocarcinoma. Short-hairpin RNA (shRNA)-mediated RNA interference was used to silence HMGA1 expression in MiaPaCa2 and PANC1 pancreatic cancer cells. Anchorage-independent proliferation was assessed by using soft agar assays. The roles of phosphatidylinositol 3-kinase (PI3-K)/Akt and extracellular signal-regulated kinase (ERK) signaling were investigated by using specific inhibitors and adenoviral dominant-negative/active Akt constructs. In vivo tumorigenicity was assessed by using a nude mouse xenograft model. Tumor HMGA1 expression was detected in 93% of patients with pancreatic adenocarcinoma. Patients with HMGA1-negative tumors had a significantly longer median survival than patients with HMGA1-expressing cancers in univariate analysis (P = .0028) and in multivariate analysis (P<.05). shRNA-mediated HMGA1 silencing resulted in significant reductions in anchorage-independent proliferation in soft agar. Forced HMGA1 overexpression promoted proliferation in soft agar through a process that was dependent on PI3-K/Akt-activited signaling, but not on mitogen-activated protein kinase (MEK)/ERK signaling. Targeted silencing of HMGA1 reduced tumor growth in vivo through reduced proliferation (Ki-67 index) and increased apoptosis (terminal deoxynucleotidyl transferase nick-end labeling). The current findings suggested that HMGA1 is an independent predictor of poor postoperative survival in patients with pancreatic adenocarcinoma. Furthermore, HMGA1 promotes tumorigenicity through a PI3-K/Akt-dependent mechanism. HMGA1 warrants further evaluation as a prognostic marker and therapeutic target in pancreatic cancer.

HMGA1 identified as a therapeutic target in pancreatic adenocarcinoma

HMGA1 identified as a therapeutic target in pancreatic adenocarcinoma

Overexpression of HMGA1 promotes anoikis resistance and constitutive Akt activation in pancreatic adenocarcinoma cells

HMGA1 proteins are architectural transcription factors that are overexpressed by pancreatic adenocarcinomas. Roles of HMGA1 in mediating the malignant phenotype of this cancer are poorly understood. We tested the hypothesis that overexpression of HMGA1 promotes resistance to anoikis (apoptosis induced by anchorage deprivation) in pancreatic cancer cells. HMGA1 cDNA was stably transfected into MiaPaCa2 human pancreatic adenocarcinoma cells (which have low baseline expression levels of HMGA1). Cells were grown in suspension on PolyHEMA-coated plates and their susceptibility to anoikis was assayed using flow cytometry. Overexpression of HMGA1 was associated with marked reductions in susceptibility to anoikis in concert with increases in Akt phosphorylation (Ser473) and in Akt kinase activity and with reductions in caspase 3 activation. Inhibition of phosphoinositidyl-3 (PI3-K)/Akt pathway with either the small molecule inhibitor LY294002 or dominant-negative Akt resulted in reversal of anoikis resistance induced by HMGA1 overexpression. Further, RNA interference-mediated HMGA1 silencing in MiaPaCa2 and BxPC3 (a human pancreatic adenocarcinoma cell line with high baseline levels of HMGA1 expression) cells resulted in significant increases in susceptibility to anoikis. Our findings suggest HMGA1 promotes anoikis resistance through a PI3-K/Akt-dependent mechanism. Given the putative associations between anoikis resistance and metastatic potential, HMGA1 represents a potential therapeutic target in pancreatic adenocarcinoma.

Fibroblast activation protein and focal adhesion kinase: novel stromal therapeutic targets in pancreatic adenocarcinoma

4094 Background: Fibroblast activation protein (FAP) is a serine protease expressed on tumor stromal fibroblasts which results in tumor growth potentiation. Focal adhesion kinase (FAK) is a protein tyrosine kinase which promotes cell growth and migration through the extracellular matrix. Given the extensive desmoplasia characteristic of pancreatic adenocarcinoma, we hypothesized that FAP and FAK would be overexpressed in pancreatic cancer and contribute to poor outcome. Methods: Twenty-nine paraffin-embedded pancreatic adenocarcinoma specimens from patients undergoing curative resection were obtained from the Fox Chase Cancer Center tumor bank. Four samples (2 normal and 2 mucinous borderline tumors) served as controls. FAP and FAK expression was assessed by immunohistochemistry and graded by staining extent (%) and intensity (0–3+). Results: Ninety percent of tumor specimens (26/29) expressed FAP in either fibroblasts surrounding tumor (FST), surrounding stroma (SS), or tumor. The highest expression level by intensity was: 3+ (14), 2+ (9), 1+ (3). A strong correlation was noted between FAP expression in FST and in SS (Pearson correlation coefficient 0.75, p<0.001). In contrast, control samples displayed no FAP expression in SS. FAK was expressed on tumor cells in all 29 samples, with three-quarters having 100% staining. In addition, median FAK expression in SS was 50%. A strong correlation was noted between percent staining of FAP and FAK in SS (Pearson correlation coefficient 0.637 (p<0.001). Conclusions: FAP is overexpressed in 90% of pancreatic adenocarcinoma specimens, with similar expression in both FST and SS. FAK is also overexpressed in SS and correlates with expression of FAP, suggesting that interaction between these proteins may contribute to pancreatic cancer invasiveness. Additional samples are being evaluated and correlation with clinical characteristics is ongoing. As targeting of FAP appears promising in preclinical models, pancreatic cancer is an excellent disease for future clinical development of stromal-directed therapeutics. No significant financial relationships to disclose.

Fibroblast activation protein and focal adhesion kinase: novel stromal therapeutic targets in pancreatic adenocarcinoma

4094 Background: Fibroblast activation protein (FAP) is a serine protease expressed on tumor stromal fibroblasts which results in tumor growth potentiation. Focal adhesion kinase (FAK) is a protein tyrosine kinase which promotes cell growth and migration through the extracellular matrix. Given the extensive desmoplasia characteristic of pancreatic adenocarcinoma, we hypothesized that FAP and FAK would be overexpressed in pancreatic cancer and contribute to poor outcome. Methods: Twenty-nine paraffin-embedded pancreatic adenocarcinoma specimens from patients undergoing curative resection were obtained from the Fox Chase Cancer Center tumor bank. Four samples (2 normal and 2 mucinous borderline tumors) served as controls. FAP and FAK expression was assessed by immunohistochemistry and graded by staining extent (%) and intensity (0–3+). Results: Ninety percent of tumor specimens (26/29) expressed FAP in either fibroblasts surrounding tumor (FST), surrounding stroma (SS), or tumor. The highest expression level by intensity was: 3+ (14), 2+ (9), 1+ (3). A strong correlation was noted between FAP expression in FST and in SS (Pearson correlation coefficient 0.75, p<0.001). In contrast, control samples displayed no FAP expression in SS. FAK was expressed on tumor cells in all 29 samples, with three-quarters having 100% staining. In addition, median FAK expression in SS was 50%. A strong correlation was noted between percent staining of FAP and FAK in SS (Pearson correlation coefficient 0.637 (p<0.001). Conclusions: FAP is overexpressed in 90% of pancreatic adenocarcinoma specimens, with similar expression in both FST and SS. FAK is also overexpressed in SS and correlates with expression of FAP, suggesting that interaction between these proteins may contribute to pancreatic cancer invasiveness. Additional samples are being evaluated and correlation with clinical characteristics is ongoing. As targeting of FAP appears promising in preclinical models, pancreatic cancer is an excellent disease for future clinical development of stromal-directed therapeutics. No significant financial relationships to disclose.

EphA2: a determinant of malignant cellular behavior and a potential therapeutic target in pancreatic adenocarcinoma.

The EphA2 receptor tyrosine kinase is overexpressed in a variety of human cancers. We sought to characterize the role of EphA2 in pancreatic adenocarcinoma and, using RNA interference (RNAi) mediated by small interfering RNA (siRNA), we determined the effects of suppressing EphA2 expression in vitro and in vivo. EphA2 expression in PANC1, MIAPaCa2, BxPC3 and Capan2 cells was assessed by Northern and Western blot. We artificially overexpressed EphA2 by transient transfection and suppressed EphA2 expression using RNAi. Cellular invasiveness was quantified by modified Boyden chamber assay. Anoikis was induced by anchorage-independent polyHEMA culture and caspase 3 activity was quantified fluorometrically. Focal adhesion kinase (FAK) phosphorylation was assessed by immunoprecipitation. EphA2 siRNA treatment was assessed in a nude mouse xenograft model. Pancreatic adenocarcinoma cells differentially express EphA2. Inherent and induced EphA2 overexpression is associated with increased cellular invasiveness and anoikis resistance. EphA2 siRNA suppresses EphA2 expression, cellular invasiveness, anoikis resistance and FAK phosphorylation in vitro and retards tumor growth and inhibits metastasis in vivo. EphA2 is both a determinant of malignant cellular behavior and a potential therapeutic target in pancreatic adenocarcinoma.