According to cancer researchers, compounds extracted from green vegetables such as broccoli and cabbage have the potential to produce pharmaceuticals that inhibit melanoma. Tests on mice showed that these compounds when combined with selenium are more resistant to tumors and safer and more effective than conventional therapy.
Gavin Robertson - associate professor of pharmacology, pathology and dermatology at Penn Medical School - said: 'There are currently no drugs aimed at proteins that stimulate melanoma production. We have produced drugs from natural compounds that inhibit tumor growth in mice to 50 to 60% with only very low doses'.
Robertson and his colleagues have previously demonstrated therapeutic potential when targeting the Akt3 protein when inhibiting the growth of melanoma. The study of finding a drug that inhibited this protein led them to a group of compounds called isothiocyanates.
These are naturally occurring chemicals in most cruciferous vegetables that are resistant to certain cancers. However, their efficacy is very low so that to be able to produce effective pharmaceuticals, a large amount cannot be produced.
Instead, Penn researchers modified the structure of the compounds by replacing sulfur bonds with selenium. They believe that the result will be a potentially higher drug that can be circulated intravenously in low doses.
Robertson explains: 'Selenium deficiency is very common in cancer patients, including those diagnosed with metastatic melanoma. In addition, selenium is also known for its ability to break down the stability of Akt protein in prostate cancer cells. To study the utility of the new product, researchers injected mice with 10 million cancer cells. Six days later, when the animals developed large tumors, they were divided into two groups and applied to different experimental forms. One group was injected with vegetable compounds and one group was injected with this compound but not selenium.
According to Robertson, 'we found that selenium-enhanced compounds significantly reduced the production of Akt3 protein and prevented its signaling network.' The modified compound also reduces mass growth by 60% , compared to the original plant-based compound.
When the researchers exposed three different melanoma cell lines in humans exposed to the two compounds, the selenium-enhanced compound was more effective in some cell lines than the other. Uses range from 30 to 70% depending on the cell type.
The exact mechanism of selenium inhibiting cancer cells has not been clarified. However, Robertson is convinced that the use of natural compounds targeting cancer-causing proteins may lead to more effective methods of treating melanoma.
Robertson said: 'We have exploited the natural things to deal with melanoma. Since then we only need a small amount to be able to kill cancer cells. This also means less harmful side effects for patients'.
Testing the new drug means it still takes several years, but the researchers envisioned a drug that could be given intravenously or added to sunscreen to prevent disease.
Other researchers include two assistants Professor Arati Sharma and Arun K. Sharma, postdoctoral researcher Subbarao V. Madhunapantula, Dhimant Desai associate professor, graduate student Sung Jin Huh, and professor Shantu Amin (faculty pharmacology), assistant professor of surgery Paul Mosca (Lehigh Valley, Health Network).
The American Cancer Society, the fund president of melanoma research, the National Institutes of Health, the Elsa U. Pardee Foundation and the Melanoma Research Foundation funded this program.