The main cause of failure in chemotherapy
Researchers from South Dakota State University, in Brookings, have demonstrated that calcitriol and calcipotriol, two active forms of vitamin D, can block a mechanism that enables cancer cells to become drug-resistant.
The mechanism is a drug transporter protein called multidrug resistance-associated protein 1 (MRP1). The protein sits in the cell wall and drives a pump that ejects cancer drugs out of the cell.
The researchers showed that calcitriol and calcipotriol can selectively hone in on cancer cells that have too much MRP1 and destroy them.
Surtaj Hussain Iram, Ph.D. — an assistant professor of chemistry and biochemistry at South Dakota State University — is the senior study author of a recent Drug Metabolism and Disposition paper about the findings.
He states that “Several epidemiologic and preclinical studies show the positive effect of vitamin D in reducing cancer risk and progression, but we are the first to discover its interaction with drug transporter protein and its ability to selectively kill drug-resistant cancer cells.”
Iram explains that calcitriol and calcipotriol cannot kill “naive cancer cells,” which have not yet developed chemoresistance. However, once the cells become drug-resistant, they fall prey to calcitriol and calcipotriol.