title: Downregulation of microRNA-34 induces cell proliferation and invasion of human mesothelial cells.
abstract: Malignant mesothelioma (MM) is an aggressive tumor with a dismal prognosis, and the molecular alterations involved in this disease remain unknown. We previously reported that microRNA-34s (miR-34s) are methylated and downregulated in MM and may play an important role in the carcinogenesis of MM. In this study, we downregulated miR-34s in human mesothelial cells to investigate the cellular effect of miR-34 knockdown. For the cell study, we used LP-9, a human mesothelial cell line, and three human primary-cultured mesothelial cell lines. RNA-based miR-34a, -34b and -34c inhibitors were transfected into these cells, and their effects on proliferation and invasion were evaluated. A scramble RNA oligonucleotide was used as a control. The protein expression status was estimated using western blotting. After miR-34 inhibitor transfection, miR-34a, -34b and -34c were downregulated in all the examined mesothelial cell lines. miR-34 inhibitor transfection significantly increased cell proliferation in all of the mesothelial cell lines, compared with the scramble control. The invasive ability also increased in the miR-34 inhibitor transfectants, compared with the scramble control, in the LP-9 cell line. Western blotting confirmed the upregulation of c-MET, phospho-c-MET, and bcl-2 proteins in LP-9 cells after miR-34 inhibitor transfection. In conclusion, our study showed that the downregulation of miR-34s induced an oncogenic phenotype in non-malignant mesothelial cells. The present study, together with the results of our previous report, strongly suggest that miR-34s play an important role in the early carcinogenic process involved in the transformation of human mesothelial cells to MM.
authors.affiliation: Department of Thoracic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Tanaka
authors.forename: Shinichi
authors.initials: S
authors.lastname: Toyooka
authors.forename: Junichi
authors.initials: J
authors.lastname: Soh
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tsukuda
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shien
authors.forename: Masashi
authors.initials: M
authors.lastname: Furukawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Muraoka
authors.forename: Yuho
authors.initials: Y
authors.lastname: Maki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ueno
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Asano
authors.forename: Takemi
authors.initials: T
authors.lastname: Otsuki
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Miyoshi
mesh_terms: D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008654:Mesothelioma / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009361:Neoplasm Invasiveness; D061251:Primary Cell Culture; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met