Abstract 2320: Oncogenic K-ras and loss of Smad4 mediate invasion by activating a NF-kappaB/EGFR axis that induces expression of MMP9/uPA in human pancreas progenitor cells.

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an extremely fatal and highly metastatic in nature. Several pathways and mutations contribute to the development and pathogenesis of PDAC. Activating K-ras mutations and inactivating mutations of Smad4 are two common genetic alterations that occur in the development and progression of PDAC. To further study the role of these two mutations in the pathogenesis of PDAC, immortalized human pancreas nestin postive cells (HPNE) were genetically modified by expressing oncogenic K-ras (GD12) and /or by shRNA knock down of Smad4. Present studies show that these two mutations caused increase in expression of EGFR and erbB2 growth factor receptors and increased expression and nuclear translocation of NF-κB. The increase in EGFR expression and nuclear translocation of NF-κB was associated with development of an invasive phenotype as measured by matrigel assays. Our data also demonstrated that MMP9 and uPA were substantially up regulated in HPNE cells that express K-ras or along with loss of Smad4 activities. MMP-9 and uPA are two extracellular matrix (ECM)-degrading proteinases known to play important roles in driving invasion and metastasis. Zymography studies confirm the expression and enzymatic activities of uPA and MMP-9 in the progenitor cells. The mechanism underlying this uPA/MMP9 induction is linked with NF-κB activation. Immuno-fluorescence, Western blot and chromatin immuno-precipitation (ChIP) analysis confirm the nuclear translocation of NF-κB RelA (p65) sub-unit, by induction of K-ras. Following signaling cascade, EGFR activated by the K-ras mediated NF-κB nuclear localization and further activation induced by loss of Smad4. Our results also suggest that the EGFR pathway as a critical mediator connecting Ras to NF-κB in proteolytic enzyme secretion as well as cancer invasion. In conclusion, the present study reveals a new insight in pancreatic progenitor cell invasion which includes signal transduction of K-ras activity and Smad4 inactivation in regulation of NF-κB/EGFR axis to induce expression of uPA and MMP9. Therefore, induction of K-ras and loss of Smad4 could play important roles in PDAC invasion through NF-κB/EGFR activation and subsequent induced expression of MMP9 and uPA, and might be suitable molecular candidates for the development of new therapeutic strategies for pancreatic cancer. Citation Format: Alakesh Bera, Shujie Zhao, Lin Cao, James W. Freeman. Oncogenic K-ras and loss of Smad4 mediate invasion by activating a NF-kappaB/EGFR axis that induces expression of MMP9/uPA in human pancreas progenitor cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2320. doi:10.1158/1538-7445.AM2013-2320