Sun Shi-Yong, Lotan Reuben
Department of Thoracic/Head and Neck Medical Oncology, Box 432, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
Crit Rev Oncol Hematol. 2002 Jan;41(1):41-55. doi: 10.1016/s1040-8428(01)00144-5.
Retinoids play an important role in regulating the growth and differentiation of normal, premalignant and malignant cell types, especially epithelial cells, mainly through interaction with two types of nuclear receptors: retinoic acid receptors (RARalpha, beta and gamma) and retinoid X receptors (RXRalpha, beta and gamma). Vitamin A deficiency in experimental animals has been associated with a higher incidence of cancer and with increased susceptibility to chemical carcinogens. This is in agreement with the epidemiological studies indicating that individuals with a lower dietary vitamin A intake are at a higher risk to develop cancer. At the molecular level, aberrant expression and function of nuclear retinoid receptors have been found in various types of cancer including premalignant lesions. Thus, aberrations in retinoid signaling are early events in carcinogenesis. Retinoids at pharmacological doses exhibit a variety of effects associated with cancer prevention. They suppress transformation of cells in vitro, inhibit carcinogenesis in various organs in animal models, reduce premalignant human epithelial lesions and prevent second primary tumors following curative therapy for epithelial malignancies such as head and neck, lung, liver, and breast cancer.
维甲酸在调节正常细胞、癌前细胞和恶性细胞类型（尤其是上皮细胞）的生长和分化中发挥重要作用，主要是通过与两种核受体相互作用：维甲酸受体（RARα、β和γ）和类视黄醇X受体（RXRα、β和γ）。实验动物中的维生素A缺乏与癌症发病率较高以及对化学致癌物的易感性增加有关。这与流行病学研究一致，这些研究表明饮食中维生素A摄入量较低的个体患癌症的风险更高。在分子水平上，已在包括癌前病变在内的各种类型癌症中发现核类视黄醇受体的异常表达和功能。因此，类视黄醇信号传导异常是致癌作用中的早期事件。药理剂量的维甲酸表现出与癌症预防相关的多种作用。它们在体外抑制细胞转化，在动物模型中抑制各种器官的致癌作用，减少人类癌前上皮病变，并预防头颈部、肺癌、肝癌和乳腺癌等上皮恶性肿瘤根治性治疗后的第二原发性肿瘤。
