Honeybee venom is a colourless, acidic liquid. Bees excrete it through their stingers into a target when they feel threatened. It contains both anti-inflammatory and inflammatory compounds, including enzymes, sugars, minerals, and amino acids. For thousands of years humans have used honey, propolis, and venom from the European honeybee Apis mellifera as medicine. More recently, scientists have discovered that honeybee venom and its active component, melittin, are toxic to a wide range of tumours — including melanoma, lung, ovarian, and pancreatic cancers — in laboratory tests.
Breast cancer is the most common cancer in women. The two aggressive types, known as triple-negative breast cancer and HER2-enriched breast cancer, are associated with the poorest outcomes. They tend to develop resistance to existing treatments. Scientists at the Harry Perkins Institute of Medical Research in Perth, Australia, and in the University of Western Australia, also in Perth, found that melittin and honeybee venom rapidly kill these cancer types, with negligible effects on normal cells. “The venom was extremely potent,” says Dr Ciara Duffy, who led the research. “We found that melittin can completely destroy cancer cell membranes within 60 minutes”.
The study also showed that venom from bumblebees, which contains no melittin, did not kill the cancer cells — even at high concentrations.
Melittin can kill cells in less than an hour by punching holes in their outer membrane. However, within 20 minutes of administration, it also disrupts the passing of chemical messages that the cells need to grow and divide.
The scientists discovered that melittin does this by preventing the activation of receptors for growth factors in the cells’ membrane. One of the reasons that HER2-enriched cancer cells and some triple-negative breast cancers grow uncontrollably is that they have large numbers of these receptors. By preventing these growth signals from getting through, melittin halts the cells’ proliferation.
As melittin creates holes in cell membranes, it may also allow existing chemotherapy drugs to penetrate and kill cancer cells. To test this possibility, the researchers treated a mouse model of triple-negative breast cancer with a combination of melittin and a drug called docetaxel. This proved more effective at shrinking the tumours than either docetaxel or melittin alone.
This strategy could potentially increase the efficacy or reduce the dosage of chemotherapy drugs, thereby reducing harmful side effects. The researchers thus suggested that honeybee venom is relatively cheap and easily obtainable, making it a good option for cancer treatment in countries with poorly resourced health services.
The writer is a master’s student of Zoology at CUK. [email protected]