Author Interviews, Cancer Research / 30.12.2014
Potential Drug Combination With Viagra May Enhance Cancer and Infection Treatments
MedicalResearch.com Interview with:
Paul Dent PhD
Massey Cancer Center,
Departments of Biochemistry and Molecular Biology
Virginia Commonwealth University, Richmond, VA 23298
Medical Research: What is the background for this study? What are the main findings?
Dr. Dent: I have worked on understanding how the drug OSU-03012 (AR-12) kills cancer cells since 2005.
The drug was originally advertised as an inhibitor of PDK1 in the PI3 kinase pathway. We found that PDK1 inhibition could not be the major way in which the drug worked. We found that the drug killed brain cancer cells through endoplasmic reticulum stress signaling. And in 2012 we published that OSU-03012 destabilized the chaperone protein GRP78, without significantly altering its transcription. Loss of GRP78 was responsible for the prolonged intense endoplasmic reticulum stress signal, that was toxic. In 2014 we published that OSU-03012 + Viagra / Cialis synergized to kill brain cancer cells. We hypothesized that Viagra / Cialis might enhance the anti-GRP78 effect of OSU-03012; and this was proven to be true.
We discovered that the OSU-03012 + Viagra combination, but not OSU-03012 alone, reduced expression of other chaperone proteins, such as HSP70, GRP94. In mice, the combination was not toxic to "normal" tissues, but was toxic to tumor cells.
In human patients the drug was found to be safe in a phase I trial, with plasma levels of up to 8 microM, and patients on trial for up to 9 months.
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