6533b7d9fe1ef96bd126b8c0

RESEARCH PRODUCT

The human p53 gene mutated at position 249per se is not sufficient to immortalize human liver cells

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A particular point mutation of the tumor suppressor gene p53, namely a G→T transversion at the third base of codon 249, is frequently detected in primary hepatocellular carcinomas from patients living in areas where the levels of dietary exposure to aflatoxin B 1 and the rates of infection with the hepatitis B virus are very high. Very recently, a nontumorigenic liver epithelial cell line (HACL-1) with a finite life-span and expressing a number of hepatocyte-specific markers was established from a human hepatocellular adenoma in our laboratory. To analyze the role of mutated p53 in the immortalization of human liver cells, we transfected HACL-1 cells with an expression vector containing a human p53 complementary DNA mutated at the third base of codon 249 and analyzed the consequences of this gene transfer on the growth properties of this cell line. HACL-1 cells transfected with mutant p53 showed no increase in their life-span (when compared with HACL-1 cells transfected with the antibiotic resistance gene alone) and did not grow in soft agar, whereas transfection of wild-type p53 into HACL-1 cells led to a proliferation stop. Thus, these results strongly support the view that the mutation at codon 249 of the p53 gene may serve as a fingerprint for aflatoxin B 1 -induced hepatocellular carcinomas, but is not, by itself, sufficient to immortalize human liver cells.