The role of vitamins A, beta-carotene, E and C in cancer cell biology.

Vitamins A (retinol, retinoids), beta-carotene (provitamin A), E (alpha-tocopherol), and C (ascorbic acid) are used in experimental, clinical and epidemiological studies for cancer chemoprevention and treatment. The cellular and metabolic effects are depending on the dose used, duration of exposure, and cancer cell type. Despite recent advances, the anticarcinogenic mechanisms remain as yet unknown. Studies regarding the role of vitamins A, beta-carotene, E and C in cancer cell biology and metabolism are of critical importance for their use in cancer treatment. Autoradiographic, ultrastructural and cell surface studies demonstrated that vitamins A, E and C are strong regulator factors of cancer cell differentiation, cell regression, membrane biogenesis, DNA, RNA, protein, and collagen synthesis, as well as transformation of precancer cells into cancer cells. These vitamins exert cytotoxic and cytostatic effects, and may reverse the cancer cell to the normal phenotype. Interrelation of vitamins A, E and C with oncogenes and growth factors play an important role in cancer cell biology. The data presented in this review can provide new insights for the understanding of anticarcinogenic mechanisms, and a rationale for the use of vitamins A, E and C in cancer chemo-prevention and treatment.