A mouse that is highly resistant to cancer—even the most aggressive types—has been created by researchers at the University of Kentucky. The breakthrough stems from a discovery by UK College of Medicine professor of radiation medicine Vivek Rangnekar and a team of researchers who found a rare tumor-suppressor gene called "Par-4" in the prostate.
The researchers discovered that the Par-4 gene kills cancer cells, but not normal cells. There are very few molecules known to specifically fight against cancer cells, which makes this a very exciting find in terms of therapeutic application.
Funded by several grants from the National Institutes of Health, Rangnekar's study is unique in that mice engineered with this gene are not developing tumors. The mice grow normally and have no defects. In fact, the mice possessing Par-4 actually live a few months longer than the control animals, indicating that they have no toxic side effects.
"We originally discovered Par-4 in the prostate, but it's not limited to the prostate. The gene is expressed in every cell type that we've looked at and it induces the death of a broad range of cancer cells, including of course, cancer cells in the prostate," said Rangnekar. "The interesting part of this study is that this killer gene is selective for killing cancer cells. It will not kill normal cells and there are very, very few selective molecules out there like this."
To further investigate the potential therapeutic benefits of this gene, Rangnekar's team introduced it into the egg of a mouse. That egg was then planted into a surrogate mother.
"The mouse itself does not express a large number of copies of this gene, but the pups do and then their pups start expressing the gene," Rangnekar said. "So, we've been able to transfer this activity to generations in the mouse."
The implications for humans could be that through bone marrow transplantation, the Par-4 molecule could potentially be used to fight cancer cells in patients without the toxic and damaging side effects of chemotherapy and radiation therapy.
"When a cancer patient goes to the clinic, they undergo chemotherapy or radiation and there are potential side effects associated with these treatments," Rangnekar said. "We got interested in looking for a molecule which will kill cancer cells and not kill normal cells, but also would not be toxic with regard to the production of side effects to the entire organism. We are thinking of this in a holistic approach that not only would get rid of the tumor, but also not harm the organism as a whole. Before this animal study, we published a lot of work indicating that in cell culture, there's no killing of normal cells. This is the proof that it doesn’t kill normal cells because the mouse is alive and healthy."
Rangnekar is hopeful that these promising results will be transferable to humans. " If you can not only treat the cancer, but also not harm the patient, that's a major breakthrough. That's happening with these animals and I think that's wonderful."
While not mentioned in the study, these results would also indicate that it is theoretically possible to genetically enhance human children, and future human generations to be resistant to cancer. However, genetic therapies are much more likely to be approved for treatment rather than prevention. There are strict bans on any genetic engineering attempting to enhance human traits rather than simply treat illness.
Even so, some philosophers and scientists such as Aubrey de Grey and John Harris argue that biologically enhancing the human race to be resistant to disease is at least as noble of an endeavor as medicine’s current focus on treating our failing bodies after they have already started to fall apart. They argue that prevention is actually more ethical (and less expensive) than treatment if we have, or could develop, the scientific means of preventing a disease or disorder in the first place.
Posted by Rebecca Sato
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