林县人尿中的亚硝基异脯氨酸对NIH3T3细胞的恶性转化作用

Malignant transformation of NIH 3T3 cells by urine NTCA in normal population of Lin-xian County

N-Nitrosothiazolidine 4-carboxylic acid (NTCA), a nonvolatile N-Nitroso compound containing sulfur was first found in the urine of normal subjects in Lin-xian county, a high risk area of esophageal cancer. The content of NTCA in the urine of the general population of Lin-xian is higher than that in Fan-xian county, a low risk area of esophageal cancer. NTCA could induce mutation in V79 cells. The results showed that NIH 3T3 cells could be induced to undergo malignant transformation by NTCA. If NIH 3T3 cells were cultured in soft agar medium, transformed cells could grow progressively to form colonies and became anchorage-independent. These transformed cells were tumorigenic in nude mice. The above results indicate that NTCA formed in vivo, being one of the risk factors of esophageal cancer in Lin-xian county, is a potential carcinogen. This investigation also demonstrates that the N-Nitroso compounds are closely related to esophageal cancer.