Newly discovered network drugs are an effective treatment for resistant prostate cancer, according to a new research.

Prostate cancer patients are typically prescribed with hormone therapies to suppress androgen stimulation. However, some of the patients no longer respond to such therapy, while others develop clinical depression.

Researchers from The Institute of Cancer Research (ICR) in London have found that a new class of prostate cancer drugs has the potential to inhibit Hsp90, which is a protein often resistant to conventional treatments.

Prostate cancer patients who developed resistance to traditional hormone treatments often have faulty androgen receptors that cannot counter the effects of Hsp90, which are crucial in the promotion and maintenance of protein complexes.

Inhibiting Hsp90 in patients with prostate cancer stops the signaling pathways that promote the growth and survival of cancer cells. Since a protein complex is destroyed, cancer cells find it hard to evade the treatment.

Prostate cancer growth and spread is androgen dependent. In cancer cells, androgen receptors can remain switched on even when androgen stimulation is unnecessary. This results in an influx of the hormone that promotes tumor growth.

For their study, researchers produced AR-V7, the most common variant of androgen receptors, and studied its activity when given the network drug. They found out that AR-V7 production was significantly reduced when administered with Hsp90 inhibitors by altering the process of its messenger RNA. Hsp90 inhibition also caused a reduction of normal androgen receptor and prostate cancer molecules GR and AKT.

Hsp90 inhibitors are called network drugs because they are able to target a number of signals in a network simultaneously instead of just acting on a sole signaling pathway, says Professor Paul Workman, lead study author and ICR's chief executive. This property can kill cancer better than just focusing on a single protein. Workman also expressed hope that the network drugs could also address and prevent drug resistance.

"It's an exciting discovery which adds a string to the bow of these cancer drugs, and means they could work against prostate cancers that have otherwise stopped responding to treatment," said Workman.

The study was funded by Wellcome Trust and was published in Cancer Research.

Photo: National Cancer Institute/National Institutes of Health | Flickr

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