The metastasis suppressor NDRG1 directly regulates androgen receptor signaling in prostate cancer

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• N-myc-downregulated gene 1 (NDRG1) exhibits significant anticancer properties, inhibiting tumor growth, survival, metastasis, and angiogenesis.
• While NDRG1's link to the androgen signaling network is suggested, the precise mechanistic relationship remains elusive.
• The androgen receptor (AR) plays a critical role in prostate cancer (PCa) progression, making its regulation a key area of research.

Purpose of the Study:

• To investigate the effect of NDRG1 on androgen receptor (AR) expression, activation, and downstream signaling pathways in various prostate cancer (PCa) cell lines.
• To elucidate the molecular mechanisms by which NDRG1 influences AR activity and prostate cancer progression.
• To identify potential therapeutic targets and biomarkers for PCa based on NDRG1's function.

Main Methods:

• Utilized LNCaP, 22Rv1, and C4-2B PCa cell lines to examine NDRG1's impact on AR signaling.
• Assessed AR activation through specific phosphorylation markers (p-AR^Ser213, p-AR^Ser81) and prostate-specific antigen (PSA) expression.
• Investigated NDRG1's interaction with AR and HSP90, and its effect on c-Jun phosphorylation and interaction with AR.
• Analyzed the role of NDRG1's CAP domain in inhibiting AR activity.
• Correlated NDRG1 and p-NDRG1 levels with clinical outcomes in PCa patient specimens.

Main Results:

• NDRG1 expression suppressed AR activation, evidenced by reduced p-AR^Ser213 and p-AR^Ser81 levels.
• NDRG1 significantly decreased the expression of prostate-specific antigen (PSA), a key AR transcriptional target.
• NDRG1 inhibited AR transcriptional activity, likely by reducing c-Jun phosphorylation and subsequent c-Jun-AR interaction.
• NDRG1 suppressed key signaling molecules (EGFR, HER2, HER3, PI3K, STAT3, NF-κB) implicated in castration-resistant prostate cancer.
• The CAP domain of NDRG1 was identified as crucial for its inhibitory effect on AR activity.
• A significant inverse correlation between NDRG1 levels and PSA was observed in prostatectomy patients who later developed metastasis.

Conclusions:

• NDRG1 plays a critical role in modulating androgen receptor (AR) signaling in prostate cancer (PCa).
• NDRG1 suppresses AR activation and downstream targets, including PSA, and inhibits pathways driving castration-resistant PCa.
• NDRG1, particularly its CAP domain, represents a promising therapeutic target and potential biomarker for PCa, especially for predicting metastasis.