Differences in Microsatellite Instability, K-ras Gene Mutation and Other Clinicopathological Features Between Left and Right Hemicolon Cancer / 胃肠病学

Background: Colon cancer is one of the most common malignant tumor of digestive system. There are differences in pathogenesis, biological behavior, gene expression between left and right hemicolon cancer. Aims: To investigate the differences in clinicopathological features, microsatellite instability (MSI) and K-ras gene mutation between left and right hemicolon cancer. Methods: Data of 144 patients with colon cancer diagnosed by postoperative pathology from June 2017 to June 2018 at Qingdao Municipal Hospital were collected. MSI was assessed by immunohistochemistry, K-ras gene mutation was detected by PCR. The differences in clinicopathological features, MSI and K-ras gene mutation between the two groups were compared. Results: Right hemicolon cancer was more common in female, and left hemicolon cancer was more common in male. The incidence of lymph node metastasis, positivity rate of CEA and MSI in right hemicolon cancer were significantly higher than left hemicolon cancer (P<0.01), while the K-ras gene mutation rate in left hemicolon cancer was significantly higher than right hemicolon cancer (P<0.05). The K-ras gene mutation in left hemicolon cancer was correlated with gender, lymph node metastasis and positivity rate of CEA (P<0.05). MSI in right hemicolon cancer was correlated with gender, age, and lymph node metastasis (P<0.05). Conclusions: There are differences in the MSI and K-ras gene mutation between left hemicolon cancer and right hemicolon cancer, which can be used as the reference for diagnosis, individualized treatment and prognosis of colon cancer.

Feasibility of testing ppENK gene methylation in stool with methylation-specific polymerase chain reaction assay in pancreatic cancer diagnosis / 中华消化杂志

Objective To evaluate the feasibility of testing the high methylation of ppENK gene in stool with methylation-specific polymerase chain reaction (MSP) assay in pancreatic cancer diagnosis.Methods Twenty-four fresh stool samples of pancreatic cancer patients and six healthy control samples were collected.The methylation status of ppENK gene in all the stool samples was detected by MSP assay.The positive rate of wild-type ppENK gene in all the stool samples was determined by polymerase chain reaction (PCR).And 10 non wild-type ppENK gene negative pancreatic cancer samples were collected,and K-ras gene mutation was detected by PCR-restriction fragment length polymorphism (RFLP).The single cell suspension of pancreatic cancer PC3 cell line was added into stool sample from the same healthy individual,the positive rate of ppENK gene methylation was detected by MSP assay.The minimum number of pancreatic cancer cell was calculated when methylation was positive.Results The rate of methylation detection in 30 samples was 0 (0/30); and the rate of non-methylation detection was 10％ (3/30).The rate of wild-type ppENK detection was 6.7％ (2/30).By PCR-RFLP assay,eight were successfully amplified and seven had mutation in 12th code of K-ras gene in 10 selected wild-type ppENK gene negative pancreatic cancer samples.The minimum number of pancreatic cancer cells needed for ppENK methylation band positive detected by MSP was 50 cell/ml.Conclusion Detecting ppENK gene methylation status in stool samples of pancreatic cancer patients by MSP assay has not yet become the method of pancreatic cancer screening and diagnosis.