Abstract 4198: MiR-17-92 cluster promotes human cholangiocarcinoma growth upon the activation of STAT3 signaling pathway.

Abstract

Abstract MiR-17-92 cluster is a potent oncogenic miRNA which has been shown to promote cell proliferation, increase angiogenesis and sustain cell survival in several cancer types. However, the potential role of miR-17-92 cluster in hepatic carcinogenesis has not been investigated. This study was designed to examine the impact of miR-17-92 in hepatic cancer cells. qRT-PCR analysis showed that the expression of miR-17-92 cluster is increased in several human hepatic cancer cell lines compared to the transformed, non-cancerous hepatic cell line, THLE-2. In addition to that, paraffin slides from human hepatic cancer sample also show higher expression of miR-19a as a result of in situ hybridization. The miR-17-92 inhibitors (blocking each individual miRNAs within the cluster) prevented hepatic cancer cell growth. In contrast, stable transfection of pri-miR-17-92 cluster increased cholangiocarcinoma cell (CCLP-1) proliferation. IL-6 treatment greatly upregulates the miR-17-92 cluster mRNA and each individual miRNA level. However, blocking IL-6/STAT3 signaling by STAT3 siRNA or STAT3 phosphorylation inhibitor both inhibit upregulation of miR-17-92 by IL-6 stimulation. Since there is a reported binding site on promoter region of miR-17-92 cluster for STAT3, we used synthesized DNA probe to precipitate STAT3, and found IL-6 treatment increases the STAT3 binding to the promoter of miR-17-92. IL-6 stimulates CCLP-1cell growth, but blocking miR-17-92 will abolish this effect. Targetscan and other prediction tools were used to predict many possible targets of miR-17-92, such as PTEN. Western blot analysis showed decreased PTEN protein level in CCLP-1 cells transfected with the pri-miR-17-92 cluster, suggesting that PTEN may represent one of the miR-17-92 downstream targets. Further experiments are undergoing to show the IL-6 activates STAT3 and thus promote cholangiocarcinoma cell growth through increasing miR-17-92 cluster level. Citation Format: Hanqing Zhu, Chang Han, Tong Wu. MiR-17-92 cluster promotes human cholangiocarcinoma growth upon the activation of STAT3 signaling pathway. [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 4198. doi:10.1158/1538-7445.AM2013-4198