The secret to a cancer cure might be lying in the body of a Brazilian social wasp, the Polybia paulista. The venom it injects in its predators as a life-saving method might possible save human lives as it is said to contain an anticancer molecule. The findings have been published in the Biophysical Journal at the beginning of this month (01.09.15).
The Brazilian social wasp, Polybia paulista. Photo credits: Prof Mario Palma/São Paulo/PA.
The toxin molecule in the venom of the Brazilian social wasp is a host-defense peptide called the MP1 (Polybia-MP1). Normally, MP1 attacks the cell membranes of harmful bacteria. It is now shown to be able to disrupt the growth of prostate and bladder cancer cells, as well as leukemic ones by disturbing their cell membranes.
The new study reveals how MP1 goes about killing cancer cells selectively while leaving normal cells untouched. It does so by interacting with lipids that are distributed in an abnormal manner on cancer cell surface membranes thereby creating gaps causing essential molecules to leak out.
The researchers are positive that this technique can be used to develop cancer therapies.
“Cancer therapies that attack the lipid composition of the cell membrane would be an entirely new class of anticancer drugs,” says co-senior study author Paul Beales, of the University of Leeds in the UK. “This could be useful in developing new combination therapies, where multiple drugs are used simultaneously to treat a cancer by attacking different parts of the cancer cells at the same time.”
One of the ways in which healthy cells differ from cancer ones has to do with the positioning of phospholipds that make up cell membranes. In the former, phospholipids called phosphatidylserine (PS) and phosphatidylethanolamine (PE) are found in the inner membrane leaflet, facing inwards. However, in cancer cells, the PS and PE are in the outer membrane leaflet, facing the cells surroundings.
The researchers found that when PS was present in the cancer cells, MP1 would bind to the membrane by a factor of 7 to 8 while PE would increase MP1’s ability to disrupt the membrane, increasing the size of the holes by a factor of 20 to 30.
“Formed in only seconds, these large pores are big enough to allow critical molecules such as RNA and proteins to easily escape cells,” Neto says. “The dramatic enhancement of the permeabilization induced by the peptide in the presence of PE and the dimensions of the pores in these membranes was surprising.”
The researchers intend to carry out further studies to decipher additional details of the mechanism.
“Understanding the mechanism of action of this peptide will help in translational studies to further assess the potential for this peptide to be used in medicine,” Beales says. “As it has been shown to be selective to cancer cells and non-toxic to normal cells in the lab, this peptide has the potential to be safe, but further work would be required to prove that.”