Osteosarcoma is the most common type of human primary malignant bone tumor characterized by an aggressive clinical course [5]. It usually develops in children and young adults. The mechanisms that orchestrate the multiple oncogenic

insults required for osteosarcoma carcinogenesis and progression are still largely unclear. To date, deregulated miRNAs and their roles in osteosarcoma development have attracted much attention. Some of them, including miR-31, miR-34, miR-20a, miR-140 and miR-143, have been reported to participate in the initiation and progression of osteosarcoma and modulate the biological properties Ku-0059436 of cancer cells [6], [7], [8], [9], [10], [11], [12], [13], [14] and [15]. However, LDK378 cell line the detailed roles of miRNAs in cancer biology, especially in osteosarcoma,

still need to be further investigated. miR-133a has been recognized as a muscle specific miRNA which may regulate myoblast differentiation and participate in myogenic and heart diseases [16], [17] and [18]. And recently, miR-133a is also reported to be an important regulator in osteogenesis, as its expression is downregulated in bone morphogenetic protein (BMP)-induced osteogenesis and it can target and suppress RunX2 expression to inhibit osteoblast differentiation [19]. But whether miR-133a is deregulated in osteosarcoma and its potential roles in osteosarcoma carcinogenesis and progression are still unknown. In this study, we have taken efforts to explore the potential roles of miR-133a in osteosarcoma development. The expression of miR-133a in clinically resected human osteosarcoma tissues was evaluated, and the correlation between miR-133a deregulation and osteosarcoma progression was analyzed. Furthermore, the roles of miR-133a in osteosarcoma development and the underlying mechanisms were investigated. Our data indicate the roles of miR-133a in the control of Dynein cell growth

and apoptosis in osteosarcoma, and suggest the potential therapeutic application of miR-133a for osteosarcoma patients. Surgically resected paired osteosarcoma tumor tissues and adjacent normal tissues used in qRT-PCR and Western blot were collected from 92 primary osteosarcoma patients who received operations between 2006 and 2009 at Changhai Hospital (Shanghai, China), and the detailed information of these patients were shown in Supplementary Table 1. Surgically removed tissues were quickly frozen in liquid nitrogen until analysis. All samples were collected with the informed consents of the patients and the experiments were approved by the ethics committee of Second Military Medical University, Shanghai, China. The investigations were conducted according to the Declaration of Helsinki principles. Total RNA, including miRNA, was extracted using miRNeasy kit (Qiagen) according to the manufacturer’s instructions.