New research from the United States has opened up the prospect that gossypol – a drug refined from cottonseed oil and previously tried and abandoned as a male contraceptive – could boost the effectiveness of treatment for prostate tumours and possibly other common cancers as well. Dr. Liang Xu, a research assistant professor at the University of Michigan, reported today (Friday 1 October) to the EORTC-NCI-AACR[1] Symposium on Molecular Targets and Cancer Therapeutics in Geneva that gossypol has been shown by many groups to have anti-tumour activities. But his team, under the leadership of Dr Marc Lippman and Dr Shaomeng Wang at the University’s Comprehensive Cancer Center, has now demonstrated that a potential small molecule inhibitor of Bcl-2/xL proteins can boost the efficacy of radiotherapy and chemotherapy. They showed that the molecule, (-)-gossypol (minus gossypol)[2], inhibited the anti-apoptotic function of Bcl-2/xL in cells, and increased induction of apoptosis (programmed cell death) and made the tumours more sensitive to radiotherapy in human prostate tumours in mice. The study demonstrates for the first time that (-)-gossypol enhances the anti-tumour efficacy of radiation therapy both in vitro and in vivo with increased induction of apoptosis.
