Identification of differentially expressed microRNAs in pulmonary and pancreatic cells transformed by the K-Ras oncogene

Abstract

Activating point mutations of the K-Ras oncogene are frequently found in a broad array of human malignancies, including hepatocellular carcinomas and lung adenocarcinomas. Even though these K-Ras mutations have been causally linked to the oncogenic process, different therapeutic approcahes to target Ras directly have failed in clinical trials. Therefore, in order to select better targets for K-Ras-related cancer therapy, key cancer-relevant K-Ras downstream effector molecules will need to be identified. A new class of molecules that have emerged as important mediators of tumor formation and progression are the microRNAs (miRNAs). Nonetheless, miRNAs involved in the malignant transformation triggered by oncogenic activation of K-Ras remain unknown. The goal of this project is to identify miRNAs that play an important role in the K-Ras-induced malignant phenotype. We hypothesize that K-Ras-induced cellular transformation alters the expression pattern of miRNAs, and therefore, the post-transcriptional gene expression regulation exerted by these molecules. To test this hypothesis, we will use DNA microarray experiments to compare the miRNA expression profile of primary epithelial lung and pancreatic cells and their K-Ras-transformed counterparts. The K-Ras-induced miRNA expression changes will be confirmed in lung and pancreatic cancer cell lines that harbor K-Ras oncogenic mutations upon manipulation of K-Ras expression by RNA interference (RNAi). Finally we will functionally validate the role of the most prominent miRNA identified by modulating its expression in pancreatic and lung cancer K-Ras positive cell lines, followed by cellular oncogenicity assays. This project is expected to yield important new insights into the molecular oncogenic mechanisms triggered by K-Ras in cancer, while, at the same time, it is expected to provide the knowledge needed for the development of novel anti-tumor therapies. (AU)