Overexpression of microRNA-21 regulating PDCD4 during tumorigenesis of liver fluke-associated cholangiocarcinoma contributes to tumor growth and metastasis
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MicroRNA, an endogenous noncoding RNA modulating gene expression, is a key molecule that by its dysregulation plays roles in inflammatory-driven carcinogenesis. This study aimed to investigate the role of oncomiR miR-21 and its target, the programmed cell death 4 (PDCD4) in tumor growth and metastasis of the liver fluke Opisthorchis viverrini-associated cholangiocarcinoma (CCA). The expression levels of miR-21 and PDCD4 were analyzed using the TaqMan miRNA expression assay and immunohistochemistry in liver tissues of both O. viverrini plus N-nitrosodimethylamine (NDMA)-treated hamsters and human CCA samples (n = 23 cases). The functional assay for miR-21 was performed in CCA cell lines by the anti-miR-21 and pre-miR-21 transfection procedures. The peak of miR-21 levels were reached at 2 (hyperplastic lesions) and 6 (CCA) months of the O. viverrini plus NDMA-induced group and had a reverse response with its target PDCD4 proteins. In human CCA, miR-21 was overexpressed in tumor tissues when compared with nontumor tissues (P = 0.0034) and had a negative correlation with PDCD4 protein (P = 0.026). It was also found that high expression of miR-21 was significantly correlated with shorter survival (P < 0.05) and lymph node metastasis (P = 0.037) of CCA patients. Transient transfection of pre-miR-21 reduced the PDCD4 level and resulted in an increase of M213 CCA cell growth and wound-induced migration ability. These results indicated that miR-21 plays a role in the carcinogenesis and metastasis of O. viverrini-associated CCA by suppressing the function of PDCD4. Modulation of aberrantly expressed miR-21 may be a useful strategy to inhibit tumor cell phenotypes or improve response to chemotherapy.
KeywordsCholangiocarcinoma miR-21 PDCD4 Cell proliferation Metastasis
This study was supported by the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (grant no PHD/0226/2551) to PC and PY, the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Health Cluster (SHeP-GMS) Khon Kaen University to PY, a grant from Khon Kaen University to NN, a grant from a Mid-Career Grant (RSA5280007), Thailand Research Fund, to NN and a grant from the Faculty of Medicine, Khon Kaen University to PY.
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