RESUMO
Charcoal-stripped fetal bovine serum (CS-FBS) is commonly used to study androgen responsiveness and androgen metabolism in cultured prostate cancer (CaP) cells. Switching CaP cells from FBS to CS-FBS may reduce the activity of androgen receptor (AR), inhibit cell proliferation, or modulate intracellular androgen metabolism. The removal of proteins by charcoal stripping may cause changes in biological functions and has not yet been investigated. Here we profiled proteins in FBS and CS-FBS using an ion-current-based quantitative platform consisting of reproducible surfactant-aided precipitation/on-pellet digestion, long-column nanoliquid chromatography separation, and ion-current-based analysis. A total of 143 proteins were identified in FBS, among which 14 proteins including insulin-like growth factor 2 (IGF-2) and IGF binding protein (IGFBP)-2 and -6 were reduced in CS-FBS. IGF-1 receptor (IGF1R) and insulin receptor were sensitized to IGFs in CS-FBS. IGF-1 and IGF-2 stimulation fully compensated for the loss of AR activity to maintain cell growth in CS-FBS. Endogenous production of IGF and IGFBPs was verified in CaP cells and clinical CaP specimens. This study provided the most comprehensive protein profiles of FBS and CS-FBS and offered an opportunity to identify new protein regulators and signaling pathways that regulate AR activity, androgen metabolism, and proliferation of CaP cells.
Assuntos
Proteínas Sanguíneas/isolamento & purificação , Células Epiteliais/efeitos dos fármacos , Neoplasias da Próstata/metabolismo , Proteômica/métodos , Testosterona/farmacologia , Adsorção , Animais , Proteínas Sanguíneas/química , Bovinos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Carvão Vegetal/química , Meios de Cultura/química , Meios de Cultura/farmacologia , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feto , Expressão Gênica , Humanos , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/isolamento & purificação , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/isolamento & purificação , Fator de Crescimento Insulin-Like I/isolamento & purificação , Fator de Crescimento Insulin-Like I/farmacologia , Fator de Crescimento Insulin-Like II/isolamento & purificação , Fator de Crescimento Insulin-Like II/farmacologia , Masculino , Próstata/efeitos dos fármacos , Próstata/metabolismo , Próstata/patologia , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Receptor IGF Tipo 1/isolamento & purificação , Receptor de Insulina/isolamento & purificação , Receptores Androgênicos/biossíntese , Receptores Androgênicos/genética , Testosterona/isolamento & purificaçãoRESUMO
Androgen deprivation therapy (ADT) is palliative and prostate cancer (CaP) recurs as lethal castration-recurrent/resistant CaP (CRPC). One mechanism that provides CaP resistance to ADT is primary backdoor androgen metabolism, which uses up to four 3α-oxidoreductases to convert 5α-androstane-3α,17ß-diol (DIOL) to dihydrotestosterone (DHT). The goal was to determine whether inhibition of 3α-oxidoreductase activity decreased conversion of DIOL to DHT. Protein sequence analysis showed that the four 3α-oxidoreductases have identical catalytic amino acid residues. Mass spectrometry data showed combined treatment using catalytically inactive 3α-oxidoreductase mutants and the 5α-reductase inhibitor, dutasteride, decreased DHT levels in CaP cells better than dutasteride alone. Combined blockade of frontdoor and backdoor pathways of DHT synthesis provides a therapeutic strategy to inhibit CRPC development and growth.
RESUMO
BACKGROUND: Eunuchs rarely, if ever, develop prostate cancer (CaP). This article reports on a 62-year-old functional eunuch from prepubertal mumps orchitis who developed clinically localized CaP. METHODS: Serum and CaP and benign prostate tissue androgen levels were measured using a validated liquid chromatography-tandem mass spectrometry assay. The assay measures testosterone; dihydrotestosterone (DHT); the adrenal androgens, androstenedione and dehydroepiandrosterone; and the androgen metabolites, androsterone and androstanedione. Gene and protein expression levels of androgen metabolism enzymes, and androgen receptor and androgen-regulated genes were measured using quantitative reverse-transcription polymerase chain reaction and immunohistochemistry, respectively. RESULTS: Intracrine androgen metabolism produced tissue DHT when serum and tissue testosterone levels were castrate and undetectable, respectively. Androgen receptor, androgen-regulated, and androgen metabolism enzyme genes were expressed but at lower levels in CaP than benign tissues. CONCLUSIONS: DHT was synthesized using the primary backdoor androgen metabolism pathway and not using androstenedione or dehydroepiandrosterone via the frontdoor or secondary backdoor pathways.
