MiR-145 modulates multiple components of the insulin-like growth factor pathway in hepatocellular carcinoma

Abstract

Profiling of microRNA expression in human cancers has highlighted downregulation of miR-145 as a common event in epithelial malignancies. Here, we describe recurrent underexpression of miR-145 in hepatocellular carcinoma (HCC) and the identification of a biological pathway by which miR-145 exerts its functional effects in liver tumorigenesis. In a cohort of 80 HCC patients, quantitative reverse transcription polymerase chain reaction corroborated reduced miR-145 expression in 50% of tumors, which also correlated with a shorter disease-free survival of patients. One HCC tumor analyzed with low endogenous miR-145 was propagated as cell line. This in vitro model HKCI-C2 maintained low miR-145 level and upon restoration of miR-145 expression, a consistent inhibitory effect on cell viability and proliferation was readily found. Flow cytometric analysis indicated that miR-145 re-expression could induce G(2)-M cell cycle arrest and apoptosis. Multiple in silico algorithms predicted that miR-145 could target a number of genes along the insulin-like growth factor (IGF) signaling, including insulin receptor substrate (IRS1)-1, IRS2 and insulin-like growth factor 1 receptor. We found protein expression of these putative targets was concordantly downregulated in the presence of miR-145. Luciferase reporter assay further verified direct target association of miR-145 to specific sites of the IRS1 and IRS2 3'-untranslated regions. Subsequent analysis also affirmed miR-145 modulation on the IGF signaling cascade by reducing its downstream mediator, namely the active β-catenin level. Taken together, our study shows for the first time the pleiotropic effect of miR-145 in targeting multiple components of the oncogenic IGF signaling pathway in HCC.

microRNA-145 promotes differentiation in human urothelial carcinoma through down-regulation of syndecan-1

“…A number of recent studies have focused on the role of miR-145 in multiple cellular pathways underlying carcinogenesis. For example, miR-145 has been found to inhibit cancer cell growth, invasion, and metastasis by suppressing EGFR and NUDT1 in lung adenocarcinoma, FSCN-1 in esophageal squamous cell carcinoma, N-cadherin in gastric carcinoma, and IGF in hepatocellular carcinoma [38][39][40][41]. In our experiments, miR-145 expression in the urothelial carcinoma cell lines T24 and KU7 induces cell senescence without apoptosis.…”

MiR-100 Inhibits Osteosarcoma Cell Proliferation, Migration, and Invasion and Enhances Chemosensitivity by Targeting IGFIR

“…20,21 Insulin-like growth factor I receptor activates multiple downstream signaling cascades, including PI3K/AKT and MAPK/ERK signaling pathways, which regulate cell proliferation, differentiation, and survival. [22][23][24][25][26][27] Recent studies have identified some miRNAs posttranscriptionally regulating IGFIR, such as miR-145, miR-375, and miR-143, suggesting that miRNAs targeting IGFIR have an important role in carcinogenesis. 28,29 In this study, we confirmed that overexpression of miR-100 in osteosarcoma cells inhibited cell proliferation, migration, invasion, and decreased the levels of p-AKT and p-ERK1/2, HIF-1a, and VEGF.…”

miR-145 suppresses embryo–epithelial juxtacrine communication at implantation by modulating maternal IGF1R

“…We have recently shown that miR-145 is important in mediating placental growth in humans (Farrokhnia et al, 2014;Forbes et al, 2012). One of the targets of miR-145 is the type-1 insulin-like growth factor receptor (IGF1R) (La Rocca et al, 2009;Law et al, 2012) and IGF1R mRNA has been previously shown to be present in endometrium (Zhou et al, 1994). Despite this, to our knowledge, its role in regulating human endometrial receptivity or implantation remains to be explored.…”