Loss of exogenous androgen dependence by prostate tumor cells is associated with elevated glucuronidation potential

Abstract

Prostate epithelial cells control the potency and availability of androgen hormones in part by inactivation and elimination. UDP-glucose dehydrogenase (UGDH) catalyzes the NAD+-dependent oxidation of UDP-glucose to UDP-glucuronate, an essential precursor for androgen inactivation by the prostate glucuronidation enzymes UGT2B15 and UGT2B17. UGDH expression is androgen stimulated, which increases the production of UDP-glucuronate, and fuels UGT-catalyzed glucuronidation. In this study, we compared the glucuronidation potential and its impact on androgen-mediated gene expression in an isogenic LNCaP model for androgen dependent versus castration resistant prostate cancer. Despite significantly lower androgen-glucuronide output, LNCaP 81 castration resistant tumor cells expressed higher levels of UGDH, UGT2B15, and UGT2B17. However, the magnitude of androgen-activated UGDH and PSA expression, as well as the AR-dependent repression of UGT2B15 and UGT2B17, was blunted several-fold in these cells. Consistent with these results, the ligand-activated binding of AR to the PSA promoter and subsequent transcriptional activation were also significantly reduced in castration resistant cells. Analysis of the UDP-sugar pools and flux through pathways downstream of UDP-glucuronate production revealed that these glucuronidation precursor metabolites were channeled through proteoglycan and glycosaminoglycan biosynthetic pathways, leading to increased surface expression of Notch 1. Knockdown of UGDH diminished Notch1 and increased glucuronide output. Overall, these results support a model in which the aberrant partitioning of UDP-glucuronate and other UDP-sugars into alternative pathways during androgen deprivation contributes to the loss of prostate tumor cell androgen sensitivity by promoting altered cell surface proteoglycan expression.

Loss-of-function mutations in UDP-Glucose 6-Dehydrogenase cause recessive developmental epileptic encephalopathy

“…UGDH WT, A44V (10 µg), and A82T (14.2 µg) were digested with 10 ng trypsin in 1x PBS pH 7.4 for 2.5 h at room temperature in the absence or presence of 1 mM UDP-glucose, 1 mM UDP-glucuronate, 5 mM NAD + , 5 mM NADH, or combinations that yielded abortive and productive ternary complexes. Samples were analyzed by western blot probed for UGDH as previously described 58 .…”

Emerging roles for UDP-glucuronosyltransferases in drug resistance and cancer progression

“…Observations in prostate cancer-cell models suggest that UDP-GlcA is preferentially channelled for the synthesis of proteoglycans such as NOTCH1 in androgen-independent cells, possibly to avoid inactivation of intracellular pools of androgens. 90 Finally, UGT activity also appears to modulate the synthesis of the glycosaminoglycan hyaluronan (HA), a constituent of the extracellular matrix, composed of GlcA units. HA possesses structural and cell-signalling functions that can affect the metastatic process by facilitating cell-cell signalling and motility.…”

A bioinformatic analysis of the inhibin-betaglycan-endoglin/CD105 network reveals prognostic value in multiple solid tumors

“…For TGFBR3 specifically, three genes revealed high discrimination between positive and negative outcomes: UGT1A9 and GLYATL1 were 25- and 35-fold more expressed in positive outcomes and P2RX3 was 11.5-fold more expressed in negative outcomes. Of interest, UGT1A9 is a UDP-glucuronosyltransferase (UGT) whose activity has been implicated in drug resistance by affecting the bioactivity of the drug [ 161 , 162 ]. We speculate that as a proteoglycan, increased TGFBR3 could compete for UDP-glucuronate acid (GlcA) and UDP-xylose, both key elements for UGT1A9 activity, thereby potentially disrupting UGT associated resistance mechanisms and increasing the efficacy of chemotherapy.…”