Cowpea Mosaic Virus Sheds Light on Cancer Therapy

A new research by University of California San Diego and Dartmouth College found that cowpea mosaic virus in legumes can trigger the immune system to fight cancer, stop metastatic cancer and prevent it from recurring. This research published in Molecular Pharmaceutics sheds new light on cancer therapy.

A Plant’s Curse is Our Cancer Cure

The cowpea mosaic virus (CPMV) is infectious among legumes but not to mammals. The immune system is triggered when the virus is injected into the tumor cells. The immune cells would consider the nanoparticles of the virus as foreign agents, then activate the attack mechanisms, and trigger the immune system. 

To demonstrate the cure’s effectiveness, the researchers injected CPMV nanoparticles and other plant virus nanoparticles into the tumor cells in rats in three dosages every seven days. The results showed that rats with an injection of CPMV-based nanoparticles have the highest survival rate. Among the survivors, they have the smallest tumors, with tumor growth paused four days after the second dose. The plant virus-based nanoparticles performed best in triggering anti-cancer immune systems among different plant viruses. However, the mechanisms still need to be verified. 

Based on the research, protein coat (capsid) on plant viruses can activate Toll-like receptors on immune cells. What’s more, the cowpea mosaic plant virus can trigger extra Toll-like receptors with its RNA, resulting in cytokines secretion, which can enhance anti-cancer immune response. Moreover, cytokine production triggered by the CPMV is special in the way that it results in prolonged immune response and increased inflammatory reactions.

Related article: AACR 2022: Stand Up to Cancer, Standing up to Treatment

Long Way to Go Before Medical Use

Professor Nicole Steinmetz, one of the principles in the research team, noted that the use of cowpea mosaic plant virus as a cancer treatment will not just take care of one tumor, but also sets up a systemic immune response against metastatic and recurrent tumors. The team has succeeded in treating rodent and canine subjects with melanoma, ovarian cancer, breast cancer, colon cancer, and glioma. 

However, the success is far away from being a medical treatment. “The answers we’ve discovered here have opened up more questions,” Professor Steinmetz said. The mechanisms of the plant-virus treatment still need clarification, including the interaction of virus nanoparticles in the cells, the potential interactions between the RNA and proteins, and why cowpea mosaic plant-virus is the only plant virus that can trigger Toll-like receptors with their RNA. When these problems are addressed, the cowpea mosaic virus may then be used in clinical settings.

Author

GeneOnline