The relationship between smoking and p53 and Ki-ras gene mutations in sputum cells of patients with lung cancer

Abstract

To study the relationship between gene's mutation in sputum cells and smoking consumption of patients with lung cancer. Sputum dispose liquid was added into 0.5ml sputum, DNA was extracted twicely with saturated phenol-chloroform and ethanol precipitate; p53 and K-ras gene mutations were detected by using SSCP-PCR and RFLP-PCR methods. Seventy-one of 110 patients with lung cancer were heavy smokers (index of smoking≥400), 55 of 71(77.5%) patients with heavy smoking were detected with gene alterations of p53 or K-ras (P<0.05). Average indexes of smoking in the patients with p53 or K-ras were 861 and 630 respectively, whereas those in non-smokers were 284 and 554 (Chi-square=36.56,P=0.002). Detection of oncogene alterations in sputum is a simple method to practice. Oncogene alteration in smoking patients with lung cancer is higher, especially in heavy smokers, than those with no smoking. The results show that heavy smoking is one of the causes in oncogene mutations of bronchus and further investigation is necessary.