The Study On The Abnormalities Of Ras, FHIT, Bcl-2/Bax Genes In Lung Cancer And Their Relationships With Smoking

Objective: lung cancer is one of the most common malignant tumors in human, and the arising, development of lung cancer has strong relationship with smoking. Ras gene is an oncogene, FHIT gene is a tumor suppressing gene, Bcl-2/Bax are apoptosis associated genes, through studying on the abnormalities of these genes in lung cancer tissue, including the mutational activation of Ras gene, deletion of FHIT gene and abnormal expression of Bcl-2/Bax gene, to get the relationship of smoking and characteristic of clinical pathology. To understand the mechanism of lung cancer arising and molecular target of smoking carcinogenesis and to provide theoretical basis of smoking control, prevention and genetic diagnosis and treatment of lung cancer.Methods: 36 lung cancer patients were randomly selected, samples of tumor and normal lung tissues were collected during operation, then store freshly in -80℃ freezer and fixed in 10% formalin separately. For each patient, clinical history was detailed collected including smoking history before operation, and pathological characteristics after operation, then comparison were made according to smoking history and pathological characteristics. The following methods were used to study the abnormality of Ras, FHIT and Bcl-2/Bax genes in the samples of each patients. (1) PCR-RFLP method was used to detect the mutation of K-ras gene in fresh frozensamples, and to study the relationship of ras gene mutation and smoking, clinical pathological characteristics. (2) immunohistochemiscal S-P technique was applied to study the expression of p21 protein in formalin fixed samples, then to study the relationship of its abnormal expression with smoking, clinical pathological characteristics. (3) RT-PCR method was used the detect the abnormal transcription of FHIT gene in fresh frozen samples, then to study the relationship of the deletion of FHIT gene in lung cancer tissue and smoking, clinical pathological characteristics, and the deletion site of exon on FHIT gene. (4) immunohistochemiscal S-P techniques were applied to detect FHIT protein expression level in formalin fixed samples, and to study the relationship of FHIT protein expression and smoking, clinical pathological characteristics. (5) immunohistochemiscal S-P techniques were applied to detect the expression of apoptosis associated gene Bcl-2 and Bax protein , to study the relationship of their abnormal expression and smoking, clinical pathological characteristics. All data were analysed using SAS 6.2 software, and x2 test was used to check differences between groups.Result: (1) The mutation rate of Ras gene in lung cancer tissue was much higher than that in normal lung tissue (p<0.01); NSCLC higher than SCLC; squamous cell cancinoma higher than adenocarcinoma; (2) The expression level of P21 protein in lung cancer tissue was much higher than that in normal lung tissue; smoking group higher than non-smoking group (p<0.01), consistent with ras gene mutation; NSCLC higher than SCLC, squamous cell cancinoma higher than adenocarcinoma; the group with lymph node metastasis was higher than that without lymph node metastasis. And the latter showed that the patients with p21 high expression will have bad prognosis. (3) There were high deletion rate of FHIT gene in lung cancer tissue, with abnormal transcription, mostly deletion of exon 5. FHIT gene deletion had relationship with smoking, smoking group higher than non-smoking group. (4) The expression of FHIT protein in lung cancer tissue was much lower than that in normal lung tissue, smoking group lower than non-smoking group (p<0.01), SCLC lower than NSCLC, squamous cell cancinoma lower than adenocarcinoma; and it had no relationship with lymphnode metastasis (p>0.05). (5) There was abnormal expression of apoptosis associated gene Bcl-2/Bax in lung cancer tissue, and these two genes had negative correlation with each other, Bcl-2 showed high expression and Bax showed low expression in in lung cancer tissue, for Bcl-2 protein expression, smoking group higher than non-smoking group (p<0.01); NSCLC...