Cancer is often treated by selectively inducing cell death—apoptosis–in tumors. However, many cancers develop resistance to this apoptosis-inducing ligand (TRAIL). Researchers are currently investigating treatments to target the TRAIL-resistant cancer cells. Will the amino acid carnitine (also called L-carnitine) become part of a new therapeutic strategy for fighting cancer?
Researchers SJ Park, SH Park, et al, with the Graduate School of East-West Medical Science, at Kyung Hee University in South Korea, are exploring the use of carnitine as part of a combination cancer treatment.
TRAIL is a protein which kills cancer cells by causing apoptosis (programmed cell death) in tumor cells. The molecules of the TRAIL protein bind to death receptors in the cancer cells. This has been a promising anti-cancer therapy, particularly because TRAIL has no toxicity to normal cells, unlike, for example, chemotherapy.
However, many cancer cells and primary tumors are resistant to TRAIL, which means the body cannot kill the cancer cells. And some cancer cells, including highly malignant tumors, which were originally sensitive to TRAIL can become resistant after repeated exposure. Can these cancer cells become vulnerable to TRAIL again?
The researchers hoped carnitine would help. Carnitine is biosynthesized in our bodies from the essential amino acids lysine and methionine. Carnitine transports long-chain molecules, and enhances the expression of various proteins, including a protein which induces apoptosis (Bax).
Study shows carnitine makes cancer cells vulnerable, promotes cell death
The researchers tested a combination of carnitine and TRAIL in lung cancer cells, colon carcinoma cells, and breast carcinoma cells. Results showed that carnitine sensitizes TRAIL-resistant cancer cells to TRAIL proteins. The cancer is now vulnerable to the apoptosis-inducing proteins, and the cancer cells are killed.
The study concluded that combining carnitine with TRAIL reverses the resistance of cancer cells. Formulating a combined delivery method of carnitine and TRAIL could become a successful new therapeutic strategy to treat TRAIL-resistant cancer cells.