Chemotherapy is the most used treatment method to help fight cancer. This is because it is one of the most effective treatments. However, sometimes chemo doesn’t work. This is mainly because the tumors that develop once chemotherapy has begun start to develop resistance against anticancer drugs, making chemotherapy less effective. Some forms of vitamin D can help make a difference here.
Researchers from South Dakota State University have found that two active forms of vitamin D can stop a drug transporter protein, multi-drug resistance-associated protein 1 (MRP1), which lets the cancer cells become drug resistant. The protein sits in the cell wall and drives a pump that ejects cancer drugs out of the cell.
The two active forms of vitamin D that can stop this protein from making chemotherapy ineffective are calcitriol and calcipotriol. Calcitriol is a synthetic vitamin D3 that’s usually used to treat hyperparathyroidism (overactive parathyroid glands) and metabolic bone disease in people who have chronic kidney failure and are not receiving dialysis. Calcitriol is also used to treat calcium deficiency (hypocalcemia) and metabolic bone disease in people who are receiving dialysis. Calcipotriol is a derivative of calcitriol and typically used in treatment of psoriasis.
The researchers found that calcitriol and calcipotriol can selectively hone in on cancer cells that have too much MRP1 and destroy them before they spread. Surtaj Hussain Iram, PhD, the study author of a recent Drug Metabolism and Disposition paper about the findings, explained that both calcitriol and calcipotriol have no ability to kill naïve cancer cells, since these have not yet developed chemoresistance. However, once they become drug resistant, the two forms of vitamin D would immediately identify them and kill them.
The researchers suggest that their findings may also have implications for the treatment of many other diseases. Along with reducing the effectiveness of cancer drugs, MRP1 can also weaken the effect of antibiotics, antivirals, anti-inflammatories, antidepressants, and drugs that treat HIV. The hope is that by reducing this protein (and others that have similar effects), drug efficacy improves and patients can take less medication yet get the same effect because the drugs are not being pumped out so much.
Photo from here, with thanks.