Down-regulation of KRAS-interacting miRNA-143 to predict prognosis and response to EGFR-targeted agents in colorectal cancer.

Abstract

e14066 Background: MicroRNA-143 is frequently down-regulated in colorectal cancer (CRC) and influence CRC cell proliferation, apoptosis and sensitivity to 5-fluorouracil. mRNA encoded by the KRAS oncogene has been identified as a target of microRNA-143. However, the prognostic significance of microRNA-143 expression and the ability to predict the patient response to EGFR-targeted agents have not been explored yet. Methods: In this study, we analyzed 77 CRC harboring wild-type KRAS and obtaining treatment with the EGFR-targeting monoclonal antibodies cetuximab or panitumumab. MicroRNA-143 expression was measured by RT-PCR in both CRC and corresponding non-neoplastic colon tissue and the expression levels were correlated with clinico-pathological characteristics. Cancer-specific survival was calculated by uni- and multivariate analyses. The progression-free survival and objective response rates on EGFR-targeted therapy were also evaluated. Results: Down-regulation of microRNA-143 was observed in 47/77 (61%) CRC. Multivariate Cox regression analysis identified low levels of microRNA-143 expression as an independent prognostic factor with respect to cancer-specific survival (HR=1.92, CI=1.1-3.4, p=0.024). A significant difference was observed with respect to progression-free survival on EGFR-targeted therapy (p=0.031, log-rank test), but there were no significant differences with regard to the objective response rate. Conclusions: Our data suggest that microRNA-143 expression levels serve as independent prognostic biomarker for KRAS wild-type CRC patients but not as predictor for EGFR-targeted therapy. In addition, we consider microRNA-143 as a potential drug target for future therapy of CRC.