Androgen-repressed phenotype in human prostate cancer

Area of Science:

• Oncology
• Cell Biology
• Cancer Research

Background:

• Established ARCaP cell line from advanced metastatic prostate cancer ascites.
• ARCaP cells display unique androgen and estrogen growth suppression, contrasting with androgen-dependent LNCaP and C4-2 cell lines.
• ARCaP is highly tumorigenic and metastatic, forming tumors and spreading to lymph nodes, lung, pancreas, liver, kidney, and bone in athymic hosts.

Purpose of the Study:

• To characterize the ARCaP cell line, focusing on its unique response to androgens and estrogens.
• To investigate the metastatic potential and cellular markers of ARCaP cells.
• To explore the role of the androgen-repressed state in advanced prostate cancer progression.

Main Methods:

• Cell line establishment and characterization from patient ascites.
• In vitro and in vivo growth assays assessing androgen and estrogen effects.
• Immunohistochemical staining for cancer markers (EGFR, c-erb B2/neu, c-erb B3, chromogranin A, bombesin, serotonin, NSE, c-met).
• Gene expression analysis (androgen receptor, prostate-specific antigen mRNA).
• Reporter assay (PSA promoter-beta-galactosidase) to assess androgen's effect on PSA expression.

Main Results:

• ARCaP cells show dose-dependent growth suppression by androgens and estrogens.
• ARCaP cells exhibit high metastatic potential to multiple organs and form ascites.
• Low androgen receptor (AR) and prostate-specific antigen (PSA) expression in ARCaP cells.
• ARCaP cells express EGFR, c-erb B2/neu, c-erb B3, and neuroendocrine markers (bombesin, serotonin, NSE), with c-met protooncogene positivity.
• Androgen represses PSA expression in ARCaP cells, confirmed by reporter assay.
• ARCaP cells secrete gelatinases A and B and stromelysin, indicating invasive potential.

Conclusions:

• The ARCaP cell line represents a novel model for studying androgen-repressed prostate cancer.
• Androgen and estrogen suppression of growth in ARCaP cells highlights a potential mechanism in advanced prostate cancer.
• The findings suggest that advanced prostate cancer can evolve into an androgen-repressed state, distinct from androgen independence.