ObjectiveTo investigate the expression and clinical significance of cyclin dependent kinase 8 (CDK8) and transforming growth factor-β1 (TGF-β1), and their correlation in human colorectal cancer tissues. MethodsThe CDK8 and TGF-β1 mRNA expressions were examined by using real-time quantitative polymerase chain reaction and the protein expresssions of them were detected by immunohistochemistry on a cohort of human colorectal cancer tissues (n=40) and corresponding adjacent tissues (n=40). The correlation between CDK8 and TGF-β1 was also analyzed. ResultsThe expression levels of CDK8 mRNA and TGF-β1 mRNA in colorectal cancer were dramatically increased compared with the corresponding adjacent tissues (P < 0.05). The expression level of CDK8 mRNA was significantly associated with lymphnode metastasis, depth of invasion, and colorectal cancer stage (P < 0.05). However, the expression level of CDK8 mRNA was no correlation with the age, gender of patients, tumor size and differentiation of colorectal cancer in this study. The expression level of TGF-β1 mRNA was significantly associated with lymphnode metastasis, depth of invasion, tumor size and colorectal cancer stage (P < 0.05). However, the expression level of TGF-β1 mRNA was no correlation with the age, gender of patients and differentiation of colorectal cancer. The expressions of CDK8 mRNA and TGF-β1 mRNA in colorectal cancer was positively correlated (r=0.387, P=0.048). ConclusionsThe upregulation of CDK8 and TGF-β1 expression may be related to the occurrence and development of colorectal cancer, and the two may have a synergistic effect, which may be related to the biological behavior and prognosis of colorectal cancer.