Methylation Analysis Of DAPK And FHIT Gene Promoter Region In Colorectal Carcinoma

Background and ObjectiveColorectal cancer is one of the most common malignant tumors in clinical practice, its incidence rate is the third among malignancies in the world.With the improvement of people’s living standard and the change in life style, the incidence and mortality rate of colorectal cancer is on the rise. Therefore, the problem we need to settle is to explore the pathogenesis of colorectal cancer and looking for prevention and treatment of colorectal cancer. The occurrence of colorectal cancer is the result of joint action of many factors, its development have a close relationship with genetic change, DNA methylation is an important epigenetic mechanism in tumorigenesis, by inactivatingtumor-suppressor gene to participate in the process of tumor. Death-associated protein kinase (DAPK) was discovered as a calcium/calmodulin dependent kinase operating as a positive mediator of apoptosis, can be activated by Fas, E2F, P53, P16, ceramide and other cytokines to participate in apoptosis in a variety of ways. FHIT gene is located on human3p14.2, widely expressed in many kinds of cells, its coding protein has activity of two adenosine triphosphate hydrolase. Many studies show that DAPK and FHIT genes are tumor-suppressor in a variety of tumor tissues showed low expression, but combined detection of both Methylation level in colorectal cancer is rarely reported. In this study, methylation-specificPCR (MSP) was used to detect methylation patterns of DAPK and FHIT gene in46cases of colorectal cancer tissues and46cases of normal colorectal tissues, its aim is to export the role and clinical significance of the methylation of DAPK and FHIT gene in colorectal cancer and to provide some reference value for the diagnosis and treatment of colorectal cancer.Methods1. Methylation-specific PCR(MSP) was used to test methylation patterns of DAPK and FHIT gene in46case of colorectal cancer tissues and normal colorectal tissues and to analyze the relation of methylation level of the two genes and cancer patients, gender, age, tumor site, degree of differentiation, lymph node metastasis, and clinical stage as well as the correlation of DAPK and FHIT gene methylation.2. SPSS17.0statistical software was applicated for statistical data analysis, statistical methods include chi-square test and spearman correlation analysis, the significance level alpha=0.05.Results1. The methylation rate of DAPK gene in colorectal cancer and normal colorectal tissues was60.87%and13.04%, respectively. The difference of methylation incidence of DAPK gene between colorectal cancer and normal colorectal tissues was statistically different(x2=22.58, P<0.05). The methylation level and degree of differentiation, lymph node metastasis was significantly associated(P<0.05),but not associated with age, gender, tumor site and clinical stage (P>0.05).2. The methylation rate of FHIT gene in colorectal cancer and normal colorectal tissues was54.35%and8.69%, respectively. The difference of methylation incidence of FHIT gene between colorectal cancer and normal colorectal tissues was statistically different((x2=22.21, P<0.05). The methylation level and degree of differentiation, lymph node metastasis was significantly associated(P<0.05),but not associated with age, gender, tumor site and clinical stage (P>0.05).3. There was significant correlation on methylation incidence between DAPK and FHIT gene in colorectal cancer.Conclusions1. The aberrant promoter methylation of DAPK and FHIT may be related with the development, progress and tumor matastasis of colorectal cancer.2. DAPK and FHIT gene methylation are positively correlated in colorectal cancer. Combined detection of DAPK and FHIT gene may be helpful to diagnosis and evaluation of the degree of malignancy of colorectal cancer.