The Relation Between The Promoter Methylation And The Protein Express Of SM22α In Human Colorectal Cancer

Objective: Colorectal cancer is one of the common malignantgastrointestinal cancers, which is a serious hazard to human health. Currentlythe disease incidence is rising in some big cities in China. The occurrence,development, invasion and metastasis of tumor is a very complex process. Aseries of extensive research has been carried out. However, the exactmechanism is unclear.The present study was designed to investigate the relationship betweenthe gene promoter methylation level and the expression of smoothmuscle22α (SM22α) protein in human colorectal cancer tissues and thematched normal tissue, and to analyze the correlation of SM22α expressionand the promoter methylation level with colorectal cancer development.Methods: Fifty two cases of colorectal carcinoma and normal colorectaltissue samples were collected from the Fourth Hospital of Hebei MedicalUniversity from July2010to December2013. The expression of SM22α andthe promoter methylation level were detected using Western blot andMS-qPCR, respectively. The clinical significances of the protein expressionand promoter methylation of SM22α were investigated based on Dukes stage,lymph node metastasis and invasion of the cancers.Results:1The expression level and promoter methylation level of SM22αin cancer tissue and the matched normal tissueWestern blot analysis show that the SM22α expression levels in67.31%of the patients (35/52) was much lower in cancer tissue than that in the normaltissue (P<0.05); The SM22α promoter methylation level of53.85%of the patients (28/52) was higher in cancer tissue than that in normaltissue(P<0.05). 2The correlation of SM22α expression and promoter methylation levelwith the clinicopathologic features in the cancer and the matched normaltissues.The result of Western blot analysis showed that the expression andpromoter methylation level of SM22α was not correlated with Dukes stage(Dukes B and Dukes C), lymph node metastasis, invasion depth (withouttumor infiltration serous and infiltrating)(P>0.05). The promoter methylationlevel of SM22α gene in at the same time, it was found that the colon cancertissues methylation level is was relatively higher than that of rectal cancergroup.3The relationship between SM22α protein expression and promotermethylation level of SM22α.Western blot and MS-qPCR for the cancer tissues of52patients showedthat,24cases were high SM22α promoter methylation level and low proteinexpression of SM22α, and13cases with low methylation and high proteinexpression compared with the normal, both high4cases, both low11cases.The SM22α gene promoter methylation was negatively correlation correlatedwith the protein expression in the colorectal cancer, there which was statisticalsignificance (r=-0.424, P<0.01).Conclusion:1The expression levels of SM22α decreased, and the promotermethylation level of SM22α increased in colorectal cancer tissues comparedwith the matched normal tissues.2SM22α protein expression and promoter methylation level were notcorrelated with Dukes stage, infiltration depth and lymph node metastasis.3There is positive negative correlation between SM22α expression andpromoter methylation level in colorectal cancer.