Browsing by Subject "androgen receptor"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Cholesterol Sulfonation Enzyme, SULT2B1b, Modulates AR and Cell Growth Properties in Prostate Cancer
    (AACR Publications, 2016-09) Vickman, Renee E.; Crist, Scott A.; Kerian, Kevin; Eberlin, Livia; Cooks, R. Graham; Burcham, Grant N.; Buhman, Kimberly K.; Hu, Chang-Deng; Mesecar, Andrew D.; Cheng, Liang; Ratliff, Timothy L.; Pathology and Laboratory Medicine, School of Medicine
    Cholesterol accumulates in prostate lesions and has been linked to prostate cancer (PCa) incidence and progression. However, how accumulated cholesterol contributes to PCa development and progression is not completely understood. Cholesterol sulfate (CS), the primary sulfonation product of cholesterol sulfotransferase (SULT2B1b), accumulates in human prostate adenocarcinoma and precancerous prostatic intraepithelial neoplasia (PIN) lesions compared to normal regions of the same tissue sample. Given the enhanced accumulation of CS in these lesions, it was hypothesized that SULT2B1b-mediated production of CS provides a growth advantage to these cells. To address this, PCa cells with RNAi-mediated knockdown (KD) of SULT2B1b were used to assess the impact on cell growth and survival. SULT2B1b is expressed and functional in a variety of prostate cells and the data demonstrate that SULT2B1b KD, in LNCaP and other androgen-responsive (VCaP and C4-2) cells, results in decreased cell growth/viability and induces cell death. SULT2B1b KD also decreases androgen receptor (AR) activity and expression at mRNA and protein levels. While AR overexpression has no impact on SULT2B1b KD-mediated cell death, addition of exogenous androgen is able to partially rescue the growth inhibition induced by SULT2B1b KD in LNCaP cells. These results suggest that SULT2B1b positively regulates the AR either through alterations in ligand availability or by interaction with critical co-regulators that influence AR activity.
  • Thumbnail Image
    Item
    Therapeutic Targeting of Sunitinib-Induced AR Phosphorylation in Renal Cell Carcinoma
    (AACR, 2018-06) Adelaiye-Ogala, Remi; Damayanti, Nur D.; Orillion, Ashley R.; Arisa, Sreevani; Chintala, Sreenivasulu; Titus, Mark A.; Kao, Chinghai; Pili, Roberto; Medicine, School of Medicine
    Androgen receptor (AR) plays a crucial role in the development and progression of prostate cancer. AR expression has also been reported in other solid tumors, including renal cell carcinoma (RCC), but its biological role here remains unclear. Through integrative analysis of a reverse phase protein array, we discovered increased expression of AR in an RCC patient–derived xenograft model of acquired resistance to the receptor tyrosine kinase inhibitor (RTKi) sunitinib. AR expression was increased in RCC cell lines with either acquired or intrinsic sunitinib resistance in vitro. An AR signaling gene array profiler indicated elevated levels of AR target genes in sunitinib-resistant cells. Sunitinib-induced AR transcriptional activity was associated with increased phosphorylation of serine 81 (pS81) on AR. Additionally, AR overexpression resulted in acquired sunitinib resistance and the AR antagonist enzalutamide-induced AR degradation and attenuated AR downstream activity in sunitinib-resistant cells, also indicated by decreased secretion of human kallikrein 2. Enzalutamide-induced AR degradation was rescued by either proteasome inhibition or by knockdown of the AR ubiquitin ligase speckle-type POZ protein (SPOP). In vivo treatment with enzalutamide and sunitinib demonstrated that this combination efficiently induced tumor regression in a RCC model following acquired sunitinib resistance. Overall, our results suggest the potential role of AR as a target for therapeutic interventions, in combination with RTKi, to overcome drug resistance in RCC.