Vitamin D has been shown to make melanoma cells less aggressive by interfering in a key signaling pathway that promotes cancer cell growth.

Melanoma is a form of skin cancer which can be initiated by genetic damage from sun exposure. Melanoma patients are therefore encouraged to reduce their sun exposure to mitigate any further damage. However, sun exposure is also essential for the body to manufacture vitamin D and previous research has identified that higher blood Vitamin D levels correlate with better survival outcomes for melanoma patients, meaning that advice to avoid sun exposure may be counterproductive.

To understand why, researchers from Cancer Research UK investigated the processes that vitamin D regulates within melanoma cells. Vitamin D binds to cells through the vitamin D receptor (VDR), who’s production is controlled by the VDR gene. The activity of the VDR gene was measured in tumour samples from melanoma patients, and compared to the respective patient’s tumour thickness and growth speed. It was found that tumours will lower levels of VDR grew faster and were more aggressive.

Mice models had their VDR expression reduced to identify the genetic impacts of lower VDR protein levels. It was found that tumours will low levels of VDR expressed genes essential for immune system activity at a lower rate. Immune cells play a key role in identifying and eliminating cancer cells, so the results suggest that vitamin D deficiency can significantly harm the immune response against cancer.

Lower levels of VDR also increased the expression of genes associated with cancer growth and spreading, particularly genes involved in the Wnt/β-catenin signalling pathway. In mice studies it was shown that increasing the levels of VDR decreased the activity of the Wnt/β-catenin signalling pathway and slowed down the growth of melanoma cells.

Although Vitamin D will not be able to cure melanoma, it could be used to increase the efficacy of existing immuno-therapy treatments. Martin Ledwick, Head Information Nurse at Cancer Research UK said “People who have been newly diagnosed with melanoma should have their vitamin D levels checked and managed accordingly. If you are worried about your vitamin D levels, it’s best to speak to your doctor who can help ensure you are not deficient.”