Synthetic Plant Hormones Offer New Cancer Treatment
With literally millions of new cancer cases being diagnosed across the globe annually, scientists are continually looking for new methods of combating this disease in all of its mutations.
Senior investigator Ronit Yarden, PhD, assistant professor in the Department of Human Science at Georgetown University Medical Center School of Nursing & Health Studies in Washington, DC and a member of Georgetown Lombardi Comprehensive Cancer Center, recently conducted a study together with colleagues, and published the results in the journal Oncotarget.
The study suggests that two synthetic plant hormones, MEB55 and ST362, could offer a new method of fighting against cancer.
The team included research collaborators from the Agricultural Research Association (ARO), Israel and University of Turin, Italy who first synthesized MEB55 and ST362. Using a technique developed at Georgetown called conditionally reprogrammed cells, which allows cells to grow indefinitely, investigators were able to study the agents in a patient’s prostate cancer cells.
The agents MEB55 and ST362 are synthetic versions of strigolactones – hormones produced in the roots of plants that regulate their growth. The team found that, when combined with another cancer drug, the agents disrupted DNA repair in prostate cancer cells, causing them to self-destruct.
The Georgetown research team are the first to investigate the hormone for its anti-cancer properties and has conducted numerous studies since 2009 which have shown that synthetic versions of strigolactones can halt growth in breast, colon, lung and prostate and a variety of other tumor cells, but the mechanisms underlying this process have been unclear until now.
The research found that the DNA repair process of cancer cells which occurs before cell division but after the cells have copied DNA, was stopped by each of the synthetic plant hormones. The PARP inhibitors shut down a second DNA repair pathway, leaving cancer cells with no alternative but to die.
“Mistakes in copying DNA are especially prevalent in cancer cells, so without any way to repair their DNA, these cells self-destruct,” explains Yarden.
Yarden and colleagues conducted the study by testing and analysing the effects of MEB55 and ST362 in conditionally reprogrammed prostate cancer cells, which are cells that do not stop growing.
Each agent was tested separately in combination with poly ADP ribose polymerase (PARP) inhibitors, which are cancer drugs that halt DNA repair in cancer cells by blocking the PARP enzyme. It was discovered that, when combined with PARP inhibitors, both MEB55 and ST362 killed the prostate cancer cells.
Published on Dec 24, 2014
First of new generation of cancer drugs granted European approval. A new drug for ovarian cancer, developed by researchers at the University of Cambridge and AstraZeneca, has become the first of new class of drugs, known as PARP-inhibitors, to be granted approval anywhere in the world. The drug, Lynparza, has been granted Marketing Authorisation from the European Commission.
The idea to use PARP inhibitors comes from its use in breast and ovarian cancer, where cancers develop due to mutated BRCA1/BRCA2 genes, Yarden said. The BRCA genes, when normal, control a DNA repair pathway, but when mutated, cannot repair genes—the same effect offered by the synthetic hormones.
“MEB55 and ST362 appear to be very promising agents. Our study suggests that when used with anti-cancer drugs called PARP inhibitors, the combination is effective and does not harm normal cells,” she added.
While the research is still in its early days and it is still too soon to hail the synthetic plant hormones as a possible cure for cancer, the research team will be continuing with the research and will begin testing the agents on animal models with various forms of the disease in the very near future.