miR-214 promotes the proliferation and invasion of osteosarcoma cells through direct suppression of LZTS1
Introduction
Osteosarcoma (OS) is the most common primary sarcoma of bone in adolescents and young adults [1]. The incidence of OS in the general population is three cases per million per year, with peak occurrence in the 15–19-year age group, in which 8–11 cases/million/year are recorded [2]. Despite extensive advancements in diagnostic methods and surgical techniques in recent years, the 5-year survival rate of osteosarcoma patients remains at 60–70% [3]. Thus, improved understanding of the mechanisms underlying osteosarcoma development and progression is urgently required to optimize therapeutic options.
MicroRNAs (miRNAs) are an emerging class of small, non-coding, single-stranded RNAs that serve as important regulators of gene expression by binding to the 3′ untranslated region (UTR) of target mRNAs, thereby leading to their translational repression and/or degradation [4], [5]. miRNAs regulate a variety of biological processes, including cell proliferation, differentiation, migration, metabolism and apoptosis [6]. In cancers, homeostatic expression of miRNAs is disrupted, resulting in aberrant gene expression in tumor initiation, development and metastasis. Multiple miRNAs have been implicated in carcinogenesis and tumor progression in OS. For example, miR-143 is reported to function as a tumor suppressor by downregulating Bcl-2 and MMP-13 [7], [8]. miR-199b-5p, miR-183, miR-34a, miR-340 and miR-16 exert tumor suppressor effects in osteosarcomagenesis through suppression of the Notch pathway [9], the oncogenes Ezrin [10], c-Met [11], ROCK1 [12], and Raf1-MEK1/2-ERK1/2 signaling [13] in OS cells, respectively. A recent miRNA microarray analysis by Jones et al. [1] revealed higher miR-214 expression in OS tissues, compared with normal bone tissues. However, the precise role of miR-214 in OS cells remains unclear at present.
In this study, we demonstrated that miR-214 is upregulated in OS and inversely correlated with LZTS1 levels. Our collective findings suggest that miR-214 directly targets 3′-UTR of the LZTS1 transcript and suppresses its expression, eventually promoting OS cell proliferation, invasion and tumor growth in nude mice.
Section snippets
Clinical specimens
Eight OS tissues and adjacent normal bone tissues were obtained from OS patients at Shanghai Jiao Tong University Affiliated Sixth People’s Hospital (Shanghai, China). The study was approved by the ethics committee of Shanghai Municipality. Written informed consent was obtained from all patients.
Cell culture
Human OS cell lines, Saos-2 and U2OS, were obtained from Cell Bank of Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences. Cells were maintained in RPMI 1640
miR-214 is upregulated in human OS tissues and inversely correlated with LZTS1 expression
To explore the potential role of miR-214 in OS development, its expression was evaluated in eight pairs of human OS and adjacent normal bone tissues using qRT-PCR. As shown in Fig. 1A, miR-214 expression was significantly higher in tumors than normal bone tissues. Potential targets of miR-214 were predicted using bioinformatics methods. LZTS1, a tumor suppressor gene containing a binding site for miR-214, was selected as the target for further analysis (Fig. 1B). qRT-PCR analysis of the above
Discussion
Emerging data have shown that miR-214 is downregulated and functions as a potential tumor suppressor in several human cancer types, including cervical cancer, intrahepatic cholangiocarcinoma, hepatoma and colorectal cancer [16], [17], [18], [19]. Conversely, miR-214 is upregulated, and displays oncogenic properties in ovarian cancer, nasopharyngeal carcinoma and gastric cancer [20], [21], [22]. These dual effects of miR-214 may be attributable to organ-specific actions and different cellular
References (31)
- et al.
Conserved seed pairing, often flanked by adenosines, indicates that thousands of human genes are microRNA targets
Cell
(2005) - et al.
MicroRNA-143 regulates human osteosarcoma metastasis by regulating matrix metalloprotease-13 expression
Mol. Ther.
(2011) - et al.
MicroRNA-199b-5p is involved in the Notch signaling pathway in osteosarcoma
Hum. Pathol.
(2013) - et al.
Down-regulation of miR-183 promotes migration and invasion of osteosarcoma by targeting Ezrin
Am. J. Pathol.
(2012) - et al.
MicroRNA-340 suppresses osteosarcoma tumor growth and metastasis by directly targeting ROCK1
Biochem. Biophys. Res. Commun.
(2013) - et al.
MiR-16 inhibits cell proliferation by targeting IGF1R and the Raf1-MEK1/2-ERK1/2 pathway in osteosarcoma
FEBS Lett.
(2013) - et al.
MicroRNA-214 suppresses growth and invasiveness of cervical cancer cells by targeting UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase 7
J. Biol. Chem.
(2012) - et al.
Down-regulation of miR-214 contributes to intrahepatic cholangiocarcinoma metastasis by targeting Twist
FEBS J.
(2012) - et al.
MicroRNA-214 downregulation contributes to tumor angiogenesis by inducing secretion of the hepatoma-derived growth factor in human hepatoma
J. Hepatol.
(2012) - et al.
Mutation analysis of the 8p candidate tumour suppressor genes DBC2 (RHOBTB2) and LZTS1 in bladder cancer
Cancer Lett.
(2005)