肿瘤相关基因RASAL1在结肠癌中的表达及临床意义

Clinical significance of RASAL1 promoter methylation and ras activity in colorectal carcinoma

AIM: To detect RASAL1 (ras GTPase-activating-like protein 1) promoter methylation and ras activity in colorectal carcinoma (CRC) and to analyze their correlation with clinical and pathological parameters.

METHODS: Methylation-specific PCR (MSP) was used to detect RASAL1 promoter methylation in forty CRC specimens and matched normal colorectal tissue specimens. Co-immunoprecipitation was used to detected ras activity in tumor and normal tissues. The correlation of RASAL1 promoter methylation and ras activity with clinical and pathological parameters was analyzed.

RESULTS: RASAL1 promoter methylation was detected in 67.5% (26/40) of colorectal cancer tissues and in 30% (12/40) of normal tissues, and the positive rate of RASAL1 promoter methylation in tumor tissues was significantly higher than that in normal tissues (P = 0.0017). The median ras activity was significantly higher in colorectal cancer tissues than in normal tissues (1.07 vs 0.52, P < 0.001). RASAL1 promoter methylation and ras activity were both positively correlated with degree of tumor differentiation, invasion depth, lymph node metastasis, and TNM stage (all P < 0.05).

CONCLUSION: High ras activity is related to RASAL1 promoter methylation, which may play an important role in the oncogenesis of CRC. RASAL1 methylation and ras activity may be novel therapeutic targets for CRC.

Association of CHD5 and KLF5 expression with prognosis in gastric carcinoma Deng Luo, Gong-Fang Zhao, Ming-Liang Lu, Hua Huang, Jiang Chang, Meng-Yao Zheng

AIM: To investigate the expression of chromodomain helicase DNA-binding protein 5 (CHD5) and Krüppel-like factor 5 (KLF5) in gastric cancer, and to evaluate whether CHD5 and KLF5 can be used as prognostic markers in gastric cancer.

METHODS: Immunohistochemistry staining was performed to detect the expression of CHD5 and KLF5 proteins in 208 surgical specimens of gastric cancer and 68 noncancerous gastric tissue specimens. The association of CHD5 and KLF5 expression in gastric cancer with the survival time of patients was retrospectively analyzed.

RESULTS: Reduced expression of CHD5 and KLF5 frequently occurred in gastric cancer. The positive rates of CHD5 and KLF5 expression in gastric cancer were 29.33% (61/208) and 38.46% (80/208), respectively. CHD5 expression was correlated with age, histologic differentiation, depth of invasion, regional lymph node metastasis, distant metastasis, and TNM stage (all P < 0.05). KLF5 expression was correlated with histologic differentiation, depth of invasion, lymph node metastasis, distant metastasis, and TNM stage (all P < 0.05). Further multivariate analysis revealed that patient's gender, tumor location, histologic differentiation, distant metastasis, TNM stage, and expression of CHD5 and KLF5 were independent prognostic factors in patients with gastric cancer. The Kaplan-Meier plot showed that the median survival was 21.00 ± 1.36 months in patients with negative expression of CHD5 and 20.00 ± 1.54 months in those with negative expression of KLF5. The median survival time was 55.00 ± 6.97 months in patients with positive CHD5 expression and 45.00±3.27 months in patients with positive KLF5 expression. The cumulative 1- and 3-year survival rates were significantly lower in patients with negative expression of CHD5 and KLF5 than in those with positive expression of these two proteins.

CONCLUSION: Reduced expression of CHD5 and KLF5 in gastric cancer is associated with tumor metastasis and poor survival. Ectopic expression of CHD5 and KLF5 proteins may play an important role in the tumorigenesis and progression of gastric carcinoma.