New therapy eradicates cancer cells without targeting healthy ones

Washington, Nov 5 : Researchers are close to developing a cancer treatment that kills malignant cells whilst leaving healthy cells untouched.

Led by Professor Cohen-Armon of Tel-Aviv University, the researchers found that potent phenanthridine derived polyADP-ribose polymerase (PARP) inhibitors efficiently eradicate MCF-7 and MDA231 breast cancer cells without impairing normal proliferating cells, such as human epithelial cells (MCF-10A), nor normal non-proliferating cells, such as neurons and cardiomyocytes.

PARP inhibitors were originally designed to protect cells from cell-death under stress conditions (e.g. stroke or inflammation).

The researchers examined human cancers depending on a constitutive activity of externally regulated kinase (ERK).

The rationale for testing PARP inhibitors in these cancers was the recently disclosed up-regulation of ERK signals in the nucleus by activated PARP-1.

However, there are other mechanisms that also come into play.

The phenanthridine PJ-34 caused a permanent G2/M cell-cycle arrest and cell death within 48-72 hours in breast cancer MCF-7 and MDA231 cells.

On the other hand, normal proliferating cells overcame the imposed G2/M cell-cycle arrest within 12 hours, survived and continued to proliferate.

In the lab, PJ-34 prevented the development of MCF-7 and MDA231 xenotransplants in nude mice without affecting their growth, development or behaviour.

Other PARP inhibitors were recently proved efficient only for treating relatively rare hereditary human cancers developed in individuals with an impaired DNA repair (BRCA gene mutation).

However, in the current research, breast cancer cells lacking the BRCA mutation were efficiently eradicated.

"This research provides a new therapeutic approach for a selective eradication of abundant human cancers," said Professor Cohen-Armon.

The study has been published in BioMed Central's open access journal Breast Cancer Research.

--ANI