Pancreatic cancer (PC) is the fourth leading cause of cancer-related deaths in the United States. The high mortality can be accredited to late clinical presentation and early metastasis. Somatic mutations in oncogene KRAS(G12D) are the most common and earliest events during development of PC, suggesting their crucial role in tumor initiation; however, the precise functional molecular mechanism(s) of action remains unclear. CXCR2, a CXC chemokine receptor, and its ligands have also been found to be important in regulating inflammation, angiogenesis, and metastasis in various cancers. The purpose of the current study was to test the functional role of CXCR2 signaling in KRAS(G12D)-induced PC development. Immunohistochemical analysis of tumors derived from PDX-cre-LSL-kras(G12D) mice demonstrated significantly higher expression of Cxcr2 and its ligands Cxcl1 and -3. Expression of Cxcr2 and its ligands Cxcl1 and -3 was observed as early as 10 weeks and increased consistently as the lesions advanced. We demonstrated the direct link between KRAS(G12D) mutation and CXCR2 signaling using cell line models hTERT-HPNE and hTERT-HPNE -E6-E7-st with or without exogenously expressed KRAS(G12D). Real time PCR, ELISA and western blot analysis of these cells revealed that KRAS (G12D) up-regulates the expression of CXCR2 and its ligands at both the transcriptional and protein levels. In order to delineate the significance of CXCR2 in KRAS(G12D) induced autocrine growth, we treated the cell line models with various concentrations of SCH-527123 (CXCR2 antagonist) or CXCR2 neutralizing antibody. Our data shows that KRAS(G12D) bearing cells show significantly (P ≤ 0.05) greater percent inhibition in cell growth in comparison to their control counterparts. Next to evaluate the role of CXCR2 autocrine signaling in KRAS(G12D) induced cell migration, we performed a scratch assay by treating the hTERT-HPNE -E6/E7-st- KRAS(G12D) cells with SCH-527123 for 24 hours. Our data demonstrated a significant inhibition of cell migration in CXCR2 antagonist treated cultures. Together, our data demonstrate that KRAS(G12D) mutation up regulates CXCR2 and its ligands, which, in turn, play key roles in the autocrine regulation of cellular growth and migration in PC.

Note: This abstract was not presented at the meeting.

Citation Format: Abhilasha Purohit, Michelle Varney, Satya Rachagani, Michel Ouellette, Surinder K. Batra, Rakesh K. Singh. CXCR2 signaling axis- a helping hand to KRAS(G12D) mutation in pancreatic cancer initiation. [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 4874. doi:10.1158/1538-7445.AM2014-4874