Shukla Y, Verma A S, Mehrotra N K, Ray P K
Industrial Toxicology Research Centre, M.G. Marg, Lucknow, India.
Cancer Lett. 1996 May 15;103(1):41-7. doi: 10.1016/0304-3835(96)04188-2.
Protein A (PA) is an immunostimulating glycoprotein (mol. wt. 43,000 kDa) obtained from Staphylococcus aureus cowan I. The antitumour property of PA is well documented in the literature in various transplantable tumours of rats and mice. In the present set of investigations, the antitumour property of PA was tested in Swiss albino mice in a two-stage initiation-promotion mouse skin carcinogenesis model. The animals were initiated topically with a single subcarcinogenic dose (52 microgram) of 7,12-dimethylbenzanthracene (DMBA). PA was administered intraperitoneally (1 microgram/animal), twice weekly for 2 weeks. Promotion was performed by twice weekly applications of 12-O- tetradecanoyl phorbol-13-acetate (TPA) at a dose of 5 microgram/animal for 32 weeks. The result showed that the treatment schedule can effectively check the onset of tumorigenesis, the cumulative number of tumours and the average number of tumours per mouse. In the PA administered group, 30% of the animals remained tumour free until the termination of the experiments (i.e. 32 weeks of promotion). Thus the present study proves that protein A can effectively inhibit DMBA initiated and TPA promoted mouse skin carcinogenesis.
蛋白A（PA）是一种从金黄色葡萄球菌科恩I型中获得的具有免疫刺激作用的糖蛋白（分子量43,000 kDa）。PA的抗肿瘤特性在文献中已被充分记录在大鼠和小鼠的各种可移植肿瘤中。在本系列研究中，在两阶段启动-促进小鼠皮肤致癌模型中对瑞士白化小鼠测试了PA的抗肿瘤特性。动物通过单次亚致癌剂量（52微克）的7,12-二甲基苯并蒽（DMBA）进行局部启动。PA通过腹腔注射（1微克/动物）给药，每周两次，共2周。促进阶段通过每周两次以5微克/动物的剂量涂抹12-O-十四酰佛波醇-13-乙酸酯（TPA），持续32周。结果表明，该治疗方案可以有效抑制肿瘤发生的起始、肿瘤的累积数量以及每只小鼠的平均肿瘤数量。在给予PA的组中，30%的动物直到实验结束（即促进阶段32周）都没有肿瘤。因此，本研究证明蛋白A可以有效抑制由DMBA启动和TPA促进的小鼠皮肤致癌作用。
