Researchers have found the social wasp Polybia paulista's venom contains toxin - called MP1 (Polybia-MP1) - which kills cancer cells without harming normal cells.
MP1 interacts with lipids that are abnormally distributed on the surface of cancer cells, creating gaping holes that allow molecules crucial for cell function to leak out.
"Cancer therapies that attack the lipid composition of the cell membrane would be an entirely new class of anticancer drugs," said co-senior study author Paul Beales, of the University of Leeds in the UK.
MP1 acts against microbial pathogens by disrupting the bacterial cell membrane. The antimicrobial peptide shows promise for protecting humans from cancer; it can inhibit the growth of prostate and bladder cancer cells, as well as multi-drug resistant leukemic cells.
However, until now, it was not clear how MP1 selectively destroys cancer cells without harming normal cells.
Beales and co-senior study author Joao Ruggiero Neto of Sao Paulo State University in Brazil suspected that the reason might have something to do with the unique properties of cancer cell membranes.
The researchers tested their theory by creating model membranes, some of which contained PE and/or PS, and exposing them to MP1.
They used a wide range of imaging and biophysical techniques to characterise MP1's destructive effects on the membranes. Strikingly, the presence of PS increased the binding of MP1 to the membrane by a factor of 7 to 8.
"Formed in only seconds, these large pores are big enough to allow critical molecules such as RNA and proteins to easily escape cells," Neto said.
"The dramatic enhancement of the permeabilisation induced by the peptide in the presence of PE and the dimensions of the pores in these membranes was surprising," Neto said.
In future studies, the researchers plan to alter MP1's amino acid sequence to examine how the peptide's structure relates to its function and further improve the peptide's selectivity and potency for clinical purposes.