The Expression Of SASH1 In Human Gastric Cancer Tissue And The Research On The Gene SASH1 In GES-1 Cell Line By RNAi

Purpose: The gene SASH1 (SAM- and SH3-domain containing 1) is a new-found candidate tumor suppressor gene. The expression of SASH1 protein in gastric cancer tissue is studied and its specific RNAi vector is constructed to silence its expression in GES-1 cell line.Methods: 1. The expression of SASH1 protein in 94 gastric cancer tissue samples and 15 adjacent tissue samples is detected by immunohistochemistry, and the relationship between its expression and gastric cancer clinical pathology is analyzed; 2. The RNAi target of the gene SASH1 is designed, and 2 SASH1 specific RNAi vectors are constructed and named by pSilencer-1.0-U6-SASH1-1 and pSilencer-1.0-U6-SASH1-2 respectively; 3. After transfection of the recombinant RNAi vectors to the GES-1 cell by LipofectamineTM 2000, the proliferation ability of GES-1 cell is analyzed by methyl thiazolyl tetrazolium (MTT) assay, and the change of the expression of SASH1 protein and mRNA in GES-1 cell are detected by immune cytochemistry and RT-PCR respectively. Meanwhile, the change of the expression of the gene BCL-2 is also analyzed.Results: 1. The positive expression rate of SASH1 protein is significantly lower in gastric cancer tissue samples than in the adjacent tissue samples (P=0.001); and its expression is related to the invasion depth (P=0.001), lymph node metastasis (P<0.001), histological differentiation (P=0.021), and TNM staging (P=0.047), but not related to the age (P=0.513) and genders (P=0.720); 2. After 72h, 96h and 120h of the transfection of pSilencer-1.0-U6-SASH1-1 vector, the proliferation ability of GES-1 cell is found significantly higher than that in the control group and pSilencer-1.0-U6-SASH1-2 group by MTT assay (P<0.05). 3. The expression level of SASH1 protein and mRNA in pSilencer-1.0-U6-SASH1-1 transfection group decreased, while the expression level of the gene BCL-2 is increased.Conclusions: 1. The expression level of SASH1 protein and gastric caner clinical pathology are closely related; 2. The recombinant vector pSilencer-1.0-U6-SASH1-1 can silence the gene SASH1 expression in GES-1 cell effectively; 3. The silencing of the expression of the gene SASH1 in GES-1 cell will promote cell proliferation; 4. After the silencing of the expression of the gene SASH1 in GES-1 cell, the gene BCL-2 expression is increased, which suggests that the biological effects caused by the downregulation of the gene SASH1 may depend on the BCL-2.