Kircheis R, Milleck J, Korobko V G, Shingarova L N, Behnke D, Schmidt H E
Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
Immunology. 1992 Jul;76(3):433-8.
Point mutations in different regions of the tumour necrosis factor-alpha (TNF-alpha) molecule influence anti-tumour cytotoxic/cytostatic activities as well as haemorrhagic tumour necrosis, tumour regression and lethal toxicity in mice. Mutations in the C-terminal region in positions 150 and 155 markedly decrease cytotoxicity for murine L929 fibroblasts and human MCF7 mammary carcinoma cells. Competitive binding experiments with 125I-labelled TNF-alpha revealed that the loss of cytotoxicity is caused by a loss of target cell binding. In contrast to the reduced activity against L929 and MCF7 cells, neither binding to nor cytostatic activity against the human myeloid leukaemia cell lines HL60 and U937 are affected. This target cell type-dependent behaviour is probably due to the fact that L929 and MCF7 cells express different types of TNF receptor compared with myeloid leukaemia cells. While a mutation in position 127 decreases the overall activity of TNF-alpha, a deletion of four N-terminal amino acids does not reduce biological activity. In vivo the TNF mutants differed in their anti-tumour effects and lethal toxicity, but a segregation of anti-tumour activity and toxicity was not observed.
肿瘤坏死因子-α（TNF-α）分子不同区域的点突变会影响抗肿瘤细胞毒性/细胞生长抑制活性，以及小鼠体内的出血性肿瘤坏死、肿瘤消退和致死毒性。第150位和第155位C末端区域的突变显著降低了对小鼠L929成纤维细胞和人MCF7乳腺癌细胞的细胞毒性。用125I标记的TNF-α进行的竞争性结合实验表明，细胞毒性的丧失是由于靶细胞结合的丧失。与对L929和MCF7细胞活性降低相反，对人髓系白血病细胞系HL60和U937的结合及细胞生长抑制活性均未受影响。这种靶细胞类型依赖性行为可能是由于L929和MCF7细胞与髓系白血病细胞相比表达不同类型的TNF受体。虽然第127位的突变会降低TNF-α的总体活性，但N末端四个氨基酸的缺失不会降低生物学活性。在体内，TNF突变体在抗肿瘤作用和致死毒性方面存在差异，但未观察到抗肿瘤活性和毒性的分离。
