Silibinin suppresses CD44 expression in prostate cancer cells

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Prostate cancer (PCa) is characterized by altered CD44 expression, with loss of CD44 standard (CD44s) and overexpression of the pro-invasive CD44v7-10 variant.
• The precise role of CD44 in the anti-proliferative effects of silibinin on PCa remained unclear.

Purpose of the Study:

• To investigate the impact of silibinin on CD44 promoter activity and expression in PCa cells.
• To evaluate the effect of silibinin on CD44v7-10 expression in a pilot clinical study of men with PCa.

Main Methods:

• PC-3M PCa cells were transfected with a CD44 promoter-luciferase construct and treated with varying silibinin concentrations.
• Quantitative reverse transcription PCR (qRT-PCR) and Western blot analysis were used to assess CD44 RNA and protein levels.
• A pilot study involved preoperative silibinin treatment in men with PCa, with subsequent immunostaining for CD44v7-10.

Main Results:

• Silibinin dose-dependently inhibited CD44 promoter activity by up to 87% in PCa cells.
• Silibinin reduced CD44 RNA levels by 90% and CD44v7-10 RNA by 70%, and decreased CD44 and CD44v7-10 protein expression.
• Silibinin inhibited Egr-1, a CD44 promoter regulator, and decreased cell adhesion to hyaluronan and fibronectin.

Conclusions:

• CD44 inhibition is a key mechanism underlying silibinin's anti-tumorigenic effects in prostate cancer.
• Silibinin demonstrates potential as a therapeutic agent by targeting CD44 dysregulation in PCa.
• Clinical efficacy of silibinin in modulating CD44v7-10 in patients requires further investigation.