Increased acid ceramidase expression depends on upregulation of androgen-dependent deubiquitinases, USP2, in a human prostate cancer cell line, LNCaP

• Published in: Journal of biochemistry (Tokyo) 2015-10, Vol.158 (4), p.309-319
• Main Authors: Mizutani, Naoki, Inoue, Minami, Omori, Yukari, Ito, Hiromi, Tamiya-Koizumi, Keiko, Takagi, Akira, Kojima, Tetsuhito, Nakamura, Mitsuhiro, Iwaki, Soichiro, Nakatochi, Masahiro, Suzuki, Motoshi, Nozawa, Yoshinori, Murate, Takashi
• Format: Article
• Language: English
• Subjects: Acid Ceramidase - antagonists & inhibitors; Acid Ceramidase - genetics; Acid Ceramidase - metabolism; Androgen Antagonists - pharmacology; Androgens - pharmacology; Antineoplastic Agents - pharmacology; Breast Neoplasms - drug therapy; Breast Neoplasms - enzymology; Breast Neoplasms - metabolism; Cell Line, Tumor; Endopeptidases - chemistry; Endopeptidases - genetics; Endopeptidases - metabolism; Enzyme Induction - drug effects; Enzyme Stability - drug effects; Female; Gene Expression Regulation, Neoplastic - drug effects; Humans; Lung Neoplasms - drug therapy; Lung Neoplasms - enzymology; Lung Neoplasms - metabolism; Male; Neoplasm Proteins - antagonists & inhibitors; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Promoter Regions, Genetic - drug effects; Prostatic Neoplasms - drug therapy; Prostatic Neoplasms - enzymology; Prostatic Neoplasms - metabolism; Prostatic Neoplasms, Castration-Resistant - drug therapy; Prostatic Neoplasms, Castration-Resistant - enzymology; Prostatic Neoplasms, Castration-Resistant - metabolism; Proteasome Endopeptidase Complex - drug effects; Proteasome Endopeptidase Complex - metabolism; Proteasome Inhibitors - pharmacology; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; RNA Interference
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/jb/mvv039

Acid ceramidase (ACDase) metabolizes ceramide to sphingosine, leading to sphingosine 1-phosphate production. Reportedly, ACDase has been upregulated in prostate cancer. However, its regulatory mechanism remains unclear. LNCaP (androgen-sensitive prostate cancer cell line) but not PC3 and DU-145, (androgen-unresponsive cell lines) exhibited the highest ACDase protein. Among three cell lines, ASAH1 mRNA level was not correlated with ACDase protein expression, and the 5'-promoter activity did not show androgen dependency, suggesting the post-transcriptional regulation of ACDase in LNCaP cells. Based on these results, LNCaP was analysed further. Casodex, androgen receptor antagonist, and charcoal-stripped FCS (CS-FCS) decreased ACDase protein and activity, whereas dihydrotestosterone in CS-FCS culture increased ACDase protein and enzyme activity. MG132, a proteasome inhibitor, prevented the decrease of ACDase protein when cultured in CS-FCS, suggesting the involvement of ubiquitin/proteasome system. Reportedly, USP2, a deubiquitinase, plays an important role in LNCaP cells. USP2 siRNA decreased ACDase protein, whereas USP2 overexpression increased ACDase protein of LNCaP cells. However, SKP2, an ubiquitin E3 ligase known to be active in prostate cancer, did not affect androgen-dependent ACDase expression in LNCaP cells. Thus, ACDase regulation by androgen in androgen-sensitive LNCaP cells is mainly due to its prolonged protein half-life by androgen-stimulated USP2 expression.