Deng D J, Hu G G, Luo X M
Cancer Institute, Chinese Academy of Medical Sciences, Beijing.
Zhonghua Zhong Liu Za Zhi. 1988 Mar;10(2):89-91.
In order to elucidate the mechanism of tumor prevention of beta-carotene, its effect on sister chromatid exchanges (SCE) induced by MNNG in cultured V79 cells, under condition free of the enzyme system to convert beta-carotene into vitamin A, was studied. It was found that SCE level was significantly increased by high doses beta-carotene (10(-5)-10(-4) M) and the enhancement of SCE was restored to its original level by addition of alpha-tocopherol (final concentration 2 micrograms/ml). This may be due to the latter inhibiting the oxidation of beta-carotene and reducing the amount of oxidated carotene, which is toxic for cultured cells. Combination of beta-carotene and alpha-tocopherol at low doses inhibited SCE induced by MNNG (P less than 0.05) but no protective activity was observed when used separately. It was also found that beta-carotene (2 x 10(-7) M) and retinol (16 micrograms/ml) inhibited SCE induced by aflatoxin B1, which is activated by S-9 mixture. The present data clearly show that the antitumor activity of beta-carotene may be attributed to both itself and its degraded compound vitamin A, and may take part in the initiation of carcinogenesis. Combination of beta-carotene and other cancer preventive drugs is more effective and safer than it used individually.
为阐明β-胡萝卜素的防癌机制，研究了在无将β-胡萝卜素转化为维生素A的酶系统的条件下，其对MNNG诱导的培养V79细胞姐妹染色单体交换（SCE）的影响。发现高剂量β-胡萝卜素（10^(-5)-10^(-4)M）可显著提高SCE水平，加入α-生育酚（终浓度2微克/毫升）后，SCE的增强恢复到原来水平。这可能是由于后者抑制了β-胡萝卜素的氧化，减少了对培养细胞有毒的氧化型胡萝卜素的量。低剂量的β-胡萝卜素与α-生育酚联合使用可抑制MNNG诱导的SCE（P<0.05），但单独使用时未观察到保护活性。还发现β-胡萝卜素（2×10^(-7)M）和视黄醇（16微克/毫升）可抑制由S-9混合物激活的黄曲霉毒素B1诱导的SCE。目前的数据清楚地表明，β-胡萝卜素的抗肿瘤活性可能归因于其本身及其降解产物维生素A，并且可能参与致癌作用的起始。β-胡萝卜素与其他防癌药物联合使用比单独使用更有效、更安全。
