Vitamin K benefits in aging and cancer

Abstract

Vitamin K is well known as a critical blood coagulation factor. In addition, epidemiological studies suggest that reduced vitamin K intake is associated with several geriatric diseases, such as osteoporosis, osteoarthritis, dementia, and arteriosclerosis. Indeed, the therapeutic benefits of vitamin K have been demonstrated in osteoporosis patients in several clinical studies. It has also been proposed that vitamin K may contribute to the prevention and treatment of some types of malignancies. Vitamin K functions as a co-factor of ?-glutamyl carboxylase (GGCX) and regulates the activity of vitamin K-dependent proteins expressed in various tissues via posttranscriptional modifications. As an additional mechanism of vitamin K action, we revealed that vitamin K activates the Steroid and Xenobiotic receptor (SXR), a member of nuclear receptor superfamily, leading to changes in gene transcription. Analysis of the bones of pregnane X receptor (PXR)- deficient mice demonstrated that the bone protective effects of vitamin K are partially mediated by SXR/PXR-dependent signaling. In certain malignancies, vitamin K exerts therapeutic activity in an SXR/PXR-dependent manner. Another distinct function of vitamin K involves apoptotic induction of leukemia cells, which may be attributed to the covalent association of vitamin K2 epoxide with pro-apoptotic protein Bak. The progress of vitamin K research has opened up new possibilities that vitamin K can be useful for prevention and treatment of a variety of diseases.