Androgen signal transduction and prostatic carcinoma

Area of Science:

• Urology
• Endocrinology
• Molecular Biology

Background:

• Androgen action is crucial for prostate gland growth, morphology, and protein expression.
• Endocrine therapy for prostate cancer relies on androgen dependence but is only temporarily effective.
• The molecular mechanisms driving androgen independence in prostate cancer remain largely unknown.

Purpose of the Study:

• To investigate the role of the androgen receptor (AR) and its potential alterations in the development of androgen independence in prostate cancer.
• To identify molecular changes in AR signaling that may lead to treatment resistance.

Main Methods:

• Immunohistochemical analysis of AR expression in therapy-responsive and unresponsive prostate tumors.
• Molecular-biology studies on prostate tumor cell lines representing late stages of cancer development.
• Detection and characterization of mutant ARs in cell lines and tumor specimens.

Main Results:

• AR expression is present in most prostate carcinomas, regardless of therapy response, ruling out AR loss as the primary cause of independence.
• Qualitative and quantitative impairments in AR expression were observed in late-stage prostate cancer cell lines.
• Mutant ARs, identified in the LNCaP cell line and tumor specimens, exhibit enhanced function compared to wild-type AR.
• The LNCaP mutant AR is activated by androgens, progestagens, estrogens, and flutamide.
• The AR715met mutant receptor is activated by androgens, adrenal androgens, and progesterone.

Conclusions:

• Loss of AR expression is not the cause of androgen independence in prostate cancer.
• Mutant ARs with altered activation profiles contribute to androgen independence and treatment resistance.
• Understanding these AR alterations is critical for developing more effective, long-term therapies for advanced prostate cancer.