The venom of bees, snakes or scorpions is essentially very well suited to hindering cancer cells in their growth. These animal poisons have one thing in common: they contain proteins and peptides which, when in isolation, can attach themselves to cancer cells. This process alone can manifestly block their proliferation and prevent the spread of malignant cells, researchers at the University of Illinois recently reported. Yet simply having the animal poisons injected is not possible – the side effects are too great: heart muscles or neurons could be harmed, occlusions or internal bleeding could occur. This is because in its original form the animal poisons act as efficiently on healthy cells as on cancer cells.
Scientists have therefore sought a way to administer tumour toxins in a targeted manner as reported at the 248th National Meeting of the American Chemical Society in San Francisco in August 2014. Nanoparticles appear to be well suited to this approach. They shield and transport the toxins directly to their site of action, effectively keeping them out of reach of reactions of the immune system. The researchers, using computer models, first simulated whether the poisons allowed themselves to be packed into nanoparticles effectively – with success. They tested the efficacy of bee venom in the clinic. A substance called melittin revealed itself in laboratory experiments to be an effective anticancer agent. Bees though produce such small amounts of the substance that it was easier for the scientists to synthesise melittin in the laboratory than to obtain it directly.
Nanoparticles as ferries
In the next step, the researchers packed melittin in nanoparticles. “The peptide toxins that we have produced are so tightly packed in the nanoparticles that they cannot during their migration through the body get away and into the blood stream and cause their side effects”, says study leader Dr. Dipanjan Pan. The nanoparticles bind to receptors that are found exclusively on tumour cells and deliver the active ingredient in a target-directed manner. In cell culture experiments, the principle has worked on breast cancer and melanoma cells. Now Pan’s plan still needs to be tested on rats and pigs before the approach can establish its potential in clinical trials.
Scorpion venom: Already TCM-tested
Scorpions are also increasingly becoming the focus of scientists. Scorpion venom has already been used in traditional medicine for many centuries as a medicinal and painkiller. At first glance, scorpion venom appears to be no suitable anti-cancer drug, after all a scorpion sting, depending on species, can for a human being have life-threatening consequences. But also here Dr. Pan has together with his research team performed experiments with promising results: the research team’s spherical nanoparticles carried TSAP-1, a toxic protein from the venom of the Brazilian yellow scorpion. When packaged in nanoparticles the scorpion venom has about 10 times more toxic an effect than when unpacked. In addition to the ability to bind exclusively to tumour cells, the peptides from scorpion venom have one other advantage: they can, in contrast to many other drugs, overcome the blood-brain barrier.
High demand leads to homeopathy
In Cuba the state pharmaceutical company Labiofam has for several years made headlines with a drug that is derived from the venom of the Cuban native blue scorpion and acts against solid tumours such as prostate cancer and brain tumours. At the beginning of the millennium, the company produced the drug after some cancer patients were able to be successfully treated with the diluted scorpion venom. According to reports, the rush for it was so great that the scorpion venom supply soon became insufficient. Meanwhile, the company however produced a homeopathic agent that is supposed to help against the negative side effects of cancer such as aches, fatigue and lack of appetite. According to research by EuroNews one litre of scorpion venom is extracted from the breeding farms of Labiofam per month. From this, 100,000 servings of the homeopathic medication can be manufactured. The agent is currently approved in China and several Latin American countries.
Scorpion venom is generally enjoying growing global popularity: due to the high demand from trade of the animals in Pakistan it has become a lucrative business. According to Al Jazeera, black scorpions are being traded for more than 50,000 US dollars. The Wall Street Journal reported as early as 2007 that the amount of money being paid for a gallon of scorpion venom added up to about 39 million US dollars. Animal rights activists already fear that the massive hunt for these animals could bring many of these species to the brink of extinction.
First registration trial
Putting aside environmental concerns, Professor Harald Sontheimer, Director of the International Research Center at the University of Alabama in Birmingham is firmly convinced that scorpion venom is an effective weapon against brain and other tumours. Already in the 1990s the German researcher discovered a peptide molecule in the venom of the Israeli giant scorpion which binds exclusively to certain cancer cells. “The peptide molecule chlorotoxin will be tested on patients in the coming year in a phase III trial”, Professor Sontheimer stated to DocCheck. The Chlorotoxin Project however does not rely on venom from animals: “We synthesise the peptide exclusively in the laboratory. For our application, the venom of scorpions would not be pure enough”.