Nitidine Chloride Inhibits SIN1 Expression in Osteosarcoma Cells

Hui Xu,Tong Cao,Xiaoqing Zhang,Ying Shi,Qing Zhang,Shuo Chai,Li Yu,Guoxi Jin,Jia Ma,Peter Wang,Yuyun Li

doi:10.1016/j.omto.2019.01.005

Abstract

Nitidine chloride (NC) has been demonstrated to exert a tumor-suppressive function in various types of human cancers. However, the detailed mechanism of NC-mediated anti-tumor effects remains elusive. It has been reported that SIN1, a component of mTORC2 (mammalian target of rapamycin complex C2), plays an oncogenic role in a variety of human cancers. Therefore, the inhibition of SIN1 could be useful for the treatment of human cancers. In this study, we explored whether NC triggered an anti-cancer function via the inhibition of SIN1 in osteosarcoma (OS) cells. An MTT assay was performed to measure the effect of NC on the cell growth of osteosarcoma cells, and flow cytometry was used to detect the apoptotic rate of the cells after NC treatment. The expression of SIN1 was detected by western blotting. Wound-healing assay and Transwell chamber invasion assay were conducted to analyze the motility of osteosarcoma cells following NC exposure. We found that exposure to NC led to the inhibition of cell growth, migration, and invasion and the induction of apoptosis. Mechanistically, we found that NC inhibited the expression of SIN1 in osteosarcoma cells. Overexpression of SIN1 abrogated the inhibition of cell growth and motility induced by NC in osteosarcoma cells. Our results indicate that NC exhibits its tumor-suppressive activity via the inhibition of SIN1 in osteosarcoma cells, suggesting that NC could be a potential inhibitor of SIN1 in osteosarcoma.

Highlights

Osteosarcoma (OS) is one of the common primary malignant bone tumors, which often occurs in adolescents and young adults.[1]
The mammalian target of rapamycin (mTOR) complexes include two distinct parts, mTORC1 and mTORC2. mTORC1 includes five components: mTOR, mammalian lethal with Sec[13] protein 8/G protein b subunit-like protein, regulatory-associated protein of mTOR (Raptor), prolinerich Akt substrate of 40 kDa (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR).[6] mTORC2 consists of six components: mTOR, Rapamycin-insensitive companion of mTOR (Rictor), DEPTOR, mLST8/GbL, protein observed with Rictor-1/proline-rich protein 5 (PROTOR), and mSIN1.6
Nitidine chloride (NC) Inhibits Osteosarcoma Cell Proliferation To investigate whether NC treatment could suppress osteosarcoma cell proliferation, we used an MTT (3-4,5-dimethylthiazol-2,5-diphenyltetrazolium bromide) assay to measure the cell growth inhibition in MG63 cells and U2OS cells treated with different concentrations of NC for 72 h

Summary

Introduction

Osteosarcoma (OS) is one of the common primary malignant bone tumors, which often occurs in adolescents and young adults.[1]. The mammalian target of rapamycin (mTOR) as a serine or threonine protein kinase has been reported to contribute to the development and progression of human cancers, including osteosarcoma.[5] It has been known that mTOR belongs to the phosphoinositide-3-kinase (PI3K)-related kinase family, which controls multiple cellular processes such as cell growth, apoptosis, and metabolism.[6] The mTOR complexes include two distinct parts, mTORC1 and mTORC2. MTORC1 includes five components: mTOR, mammalian lethal with Sec[13] protein 8/G protein b subunit-like protein (mLST8/ GbL), regulatory-associated protein of mTOR (Raptor), prolinerich Akt substrate of 40 kDa (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR).[6] mTORC2 consists of six components: mTOR, Rapamycin-insensitive companion of mTOR (Rictor), DEPTOR, mLST8/GbL, protein observed with Rictor-1/proline-rich protein 5 (PROTOR), and mSIN1 ( named as mitogenactivated protein kinase-associated protein 1 [MAPKAP1]).[6] It has been demonstrated that mTOR is a key sensor for metabolic and nutrient stresses to control cellular metabolism, cellular growth, and survival.[7] SIN1 phosphorylation enhanced the activity of mTORC2,8 suggesting an important role of SIN1 in cancer development and progression. The inhibition of SIN1 may be a promising strategy for cancer treatment

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