MP47-09 MOLECULAR CHARACTERIZATION OF SARCOMATOID CLEAR CELL RENAL CELL CARCINOMA

Abstract

METHODS: We detected the expression of sox7 in RCC cell lines and primary RCC tissues by semi-quantitative RT-PCR, quantitative RT-PCR and western-blot.we also used Methylation-specific PCR and Bisulfite Genomic Sequencing to observe the methylation status of sox7 in cell lines, primary RCC tissues and RCC surgical margin tissues. In order to further verify the tumor suppressive effects of sox7, cell functional experiments including colony formation,wound-healing assay and transwell were used with 786-O and A498 cell lines.we also measured the mRNA levels of survivin and cyclinD1 to examine the relationship between WNT signaling pathway and sox7. RESULTS: The expression level of sox7 was significantly down-regulated in RCC cell lines (7/9) and primary RCC tissues by aberrant promoter methylation, compared with nontumorigenic cells and adjacent normal tissues. By analyzing the correlation between clinical features and sox7 methylation status. Sox7 methylation status was detected in 21% of kidney tumour samples, whereas only rarely methylated in surgical margin tissues. The expression level of sox7 increased after pharmacologic demethylation treatment. Ectopic expression of sox7 inhibits cell proliferation through inducing G0/G1 cell cycle arrest,overexpression of sox7 can also suppress migration,and invasion of renal cancer cells in vitro. Moreover, mRNA expression level of Wnt signaling pathway targeted cyclinD1 and survivin were reduced upon sox7 overexpression in 786-o and A498 RCC cells. CONCLUSIONS: In conclusion,our results first imply that sox7 functions as a tumor suppressor in RCC and is frequently down-regulated,which was mainly due to the DNA promoter hypermethylation. The methylation of sox7 is frequently occured in RCC patients of early stage. Therefore sox7 may be regarded as a biomarker for diagnosis of RCC.