Identification of a Pro-and Anti-apoptotic controlling sequence in Human Prostate-distributed DHT-metabolizing UGT-2B15 and UGT-2B17 respectively

Wednesday, September 24, 2014 — Poster Session IV
10:00 a.m. –12:00 p.m.	FAES Academic Center	NICHD	CANCER-5

Authors

• N.K. BASU
• M. Basu
• I.S. Owens

Abstract

Human prostate basal cell distributed UDP- glucuronosyltransferase (UGT) 2B17 and its 97%-identical UGT-2B15 homolog metabolize di-hydrotestosterone (DHT) and its 5α-androstane- 3α,17β- diol metabolite. We have confirmed UGT-2B17 has 4 / 5 predicted phosphorylation sites found in luminal cell-distributed UGT-2B15 that support regulated-phosphorylation for two different functions. Mass spectrometry confirmed UGT-2B17 has a triple-phosphorylated sequence, TYS, at position 98-100. Also, at least one phosphate per isozyme undergoes on-going phosphate signaling at a non-fixed active site that enables catalysis of an unspecified number of substrates, according to 6/19 human UGTs examined. Following exchange of IYG in wt-2B15 for TYS in wt-2B17 at positions 98-100 and transfections into COS-1 cells, 2B17(IYG) generated 10-fold greater in-cellulo caspases 8/3 activations over wt-2B15, while 2B15(TYS) suppressed activation of caspases 8/3 over 50% of wt-2B15 levels. Evidence indicates the triple-phosphorylated TYS creates a signaling site involving Src and PKCε that is anti-apoptotic, while the Src-specific binding/phosphorylation site at position 98-100 in UGT-2B15 is pro-apoptotic. Following treatment with Src inhibitors (including curcumin) led to the finding that UGT-2B15-containing prostate LNCaP cells or expression of different UGT2B15/2B17 constructs in PC3 cells showed high levels of apoptosis compared to non-treated cells. Evidence indicates UGT-2B15 has potential to be a unique-clinical-marker.

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