SOCS3 Modulates the Response to Enzalutamide and Is Regulated by Androgen Receptor Signaling and CpG Methylation in Prostate Cancer Cells

Abstract

The proinflammatory cytokine IL6 is associated with bad prognosis in prostate cancer and implicated in progression to castration resistance. Suppressor of cytokine signaling 3 (SOCS3) is an IL6-induced negative feedback regulator of the IL6/Janus kinase (JAK)/STAT3 pathway. This study reveals that the SOCS3 promoter is hypermethylated in cancerous regions compared with adjacent benign tissue in prostate cancer using methylation-specific qPCR. A series of in vitro experiments was performed to assess the functional impact of low SOCS3 expression during anti-androgen treatment. Using lentivirus-mediated knockdown, it was demonstrated for the first time that SOCS3 regulates IL6/JAK/STAT3 signaling in androgen receptor-positive LNCaP cells. In addition, SOCS3 mRNA is upregulated by the anti-androgens bicalutamide and enzalutamide. This effect is caused by androgen receptor-mediated suppression of IL6ST and JAK1 expression, which leads to altered STAT3 signaling. Functionally, knockdown of SOCS3 led to enhanced androgen receptor activity after 3 weeks of enzalutamide treatment in an inflammatory setting. Furthermore, the stemness/self-renewal associated genes SOX2 and NANOG were strongly upregulated by the long-term treatment, and modulation of SOCS3 expression was sufficient to counteract this effect. These findings prove that SOCS3 plays an important role during anti-androgen treatment in an inflammatory environment.Implications: SOCS3 is frequently inactivated by promoter hypermethylation in prostate cancer, which disrupts the feedback regulation of IL6 signaling and leads to reduced efficacy of enzalutamide in the presence of inflammatory cytokines.

The Ca2+ influx through the mammalian skeletal muscle dihydropyridine receptor is irrelevant for muscle performance

“…TA muscles from 2 to 3 months old nc DHPR and wt mice were excised, homogenized and lysed in sample buffer containing 250 mM Tris-HCl (pH 8.5), 2% lithium dodecyl sulfate, 10% glycerol and 0.5 mM EDTA and centrifuged at RT, 16,000× g for 5 min. Protein concentration measurements and separation by SDS-polyacrylamide gel electrophoresis on 3–8% Tris-Acetate or 4–12% Bis-Tris NuPAGE gels (Thermo Fisher Scientific) was performed as described previously 67 . Immunostaining was performed with different primary antibodies followed by appropriate secondary antibodies (Supplementary Table 3 ).…”

The STAT3 Inhibitor Galiellalactone Reduces IL6-Mediated AR Activity in Benign and Malignant Prostate Models

“…Circulating IL6 levels are increased in CRPC patients and IL6 is a predictive biomarker for poor prognosis (8). The canonical IL6 downstream mediator STAT3 is highly activated in metastatic samples from CRPC patients, and STAT3 activity is increased upon AR inhibition in LNCaP cells (9,10). Furthermore, IL6 is a well-known activator of the AR and has been proposed to induce ligand-independent (outlaw) AR activity (11).…”

Cancer Stem Cells: Devil or Savior—Looking behind the Scenes of Immunotherapy Failure

“…In breast cancer, key CSC-related gene pathways are finely regulated by epigenetic mechanisms and their inhibition affects cancer cell survival, self-renewal, tumorigenesis, and progression [92]. For instance, epigenetic modifications regulate genes of the Notch and WNT pathways, which control normal mammary development and breast cancer self-renewal [93]. Moreover, nuclear receptor corepressor 2, which recruits histone deacetylases (HDACs) to the promoter regions of Notch target genes (e.g., MYC and HES1) to regulate their transcription [94], has been found to be upregulated as a result of reduced recruitment of corepressor complexes with chromatin-remodeling activity, finally resulting in enhanced transcription of Notch target genes [95].…”