| 其他摘要 | Lung cancer is the most common type of cancer in the world. With the increase of smoking and environment pollution, the morbidity and mortality rate of lung cancer are growing rapidly. Lung cancer has become the leading cause of cancer-related mortality in China. Both tumor suppressor genes and oncogenes are involved in the pathogenesis and progression of non-small cell lung cancer (NSCLC). Analyse of genetic abnormalities in tumors have been proved helpful in searching for new tumor suppressor genes and oncogenes. Chromosomal aberrations associated with mutations of tumor suppressor genes or gene amplifications of dominant oncogenes are common genetic abnormalities in tumors, including lung cancer.Previously, we showed, using karyotypic and loss of heterozygosity (LOH) analyses, that chromosome arm 12q abnormalities occurred in NSCLCs. Here, we examined mRNA expression of 20 genes within chromosome band 12q13 by quantitative real-time polymerase chain reaction in NSCLCs. Of these 20 genes, nine were upregulated, while two were downregulated. Among the 9 upregulated genes, mRNA values of RACGAP1, MCRS1, EIF4B, WNT1, and PTGES3 were significantly higher in NSCLCs compared with that from normal lung tissue. Subsequently, overexpression of microspherule protein 1(MCRS1) was confirmed at the protein level in tissues and cultured cells of lung cancer by immunostaining and Western blot. Interestingly, MCRS1 exhibits different localization in the mitotic cells of cultured immortalized human bronchial epithelial cells and lung cancer cells. These findings indicate that MCRS1 may be a novel cancer-related gene in NSCLC.MCRS1 is localized to the nucleus with known roles in transcription regulation, cellular transformation, and tumorigenesis. As MCRS1 overexpression in NSCLCs, we investigated its roles in NSCLC by RNAi and examined tumor growth, migration and invasion. (1) We found that MCRS1 silencing inhibited cell proliferation, increased apoptosis, and induced cell cycle arrest at the G1 phase in lung cancer cells. (2) MCRS1 knockdown also induced the morphological alteration, increased the monolayer integrity, decreased cellular invasion and metastasis, and attenuated stemness and drug resistance (cisplatin and cetuximab) in NSCLC cells. The levels of MCRS1 mRNA expression were associated with the tumor metastasis in NSCLC patients. These findings suggested that MCRS1 could play vital roles in the development and progression of lung cancer.To further explore molecular targets associated with MCRS1 activity in NSCLCs，we determined mRNA or microRNA (miRNA) expression profiles of cultured cells with or without RNAi mediated MCRS1 knockdown. (1) Downstream effectors of MCRS1 that were clarified by analysis of mRNA profiles and confirmed by the q-RT-PCR after MCRS1 knockdown, included cell junction molecules such as ZO-1, occluding, E-cadherin, and DSG2, as well as Notch family. (2) MCRS1 regulated miR-155 expression through assessing microRNA (miRNA) profiles after the MCRS1 silencing. RNAi experiments also confirmed that miR-155 expression could be induced by MCRS1 over-expression, and the enforced expression of miR-155 recapitulated effects of MCRS1 on the cell growth and invasion. Altogether, these results indicated that MCRS1 over-expression promoted the epithelial-mesenchymal transition (EMT) program and tumor invasion/metastasis in NSCLCs via influence on up-regulation of miR-155 and down-regulation of cell junction molecules.We also investigated the molecular mechanisms underlying MCRS1 alteration. (1) We analyzed MCRS1 DNA copy numbers. Alterations of MCRS1 DNA copy numbers were consistent with levels of MCRS1 mRNA, and MCRS1 DNA copy numbers were dramatically elevated in NSCLC tissues and culture cells compared with non-cancerous lung tissues and culture immortalized human bronchial epithelial cells, respectively. (2) Based on systematic studies including analysis of miRNA profiles, bioinformational prediction, comparison of mi |
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