The role of thiamine in cancer: possible genetic and cellular signaling mechanisms.

The relationship between supplemental vitamins and various types of cancer has been the focus of recent investigation, and supplemental vitamins have been reported to modulate cancer rates. A significant association has been demonstrated between cancer and low levels of thiamine in the serum. Genetic studies have helped identify a number of factors that link thiamine to cancer, including the solute carrier transporter (SLC19) gene, transketolase, transcription factor p53, poly(ADP-ribose) polymerase-1 gene, and the reduced form of nicotinamide adenine dinucleotide phosphate. Thiamine supplementation may contribute to a high rate of tumor cell survival, proliferation and chemotherapy resistance. Thiamine has also been implicated in cancer through its effects on matrix metalloproteinases, prostaglandins, cyclooxygenase-2, reactive oxygen species, and nitric oxide synthase. However, some studies have suggested that thiamine may exhibit some antitumor effects. The role of thiamine in cancer is controversial. However, thiamine deficiency may occur in patients with cancer and cause serious disorders, including Wernicke's encephalopathy, that require parenteral thiamine supplementation. A very high dose of thiamine produces a growth-inhibitory effect in cancer. Therefore, further investigations of thiamine in cancer are needed to clarify this relationship.