"This finding implicates that targeting PCNA/AR interaction could be an innovative strategy for therapy against CRPC."
BUFFALO, NY – June 4, 2025 – A new research paper was published in Volume 16 of Oncotarget on May 20, 2025, titled " Targeting PCNA/AR interaction inhibits AR-mediated signaling in castration resistant prostate cancer cells ."
In this study, authors Shan Lu and Zhongyun Dong from the University of Cincinnati College of Medicine investigated how interfering with a protein interaction could reduce prostate cancer growth. Their study based on prostate cancer cells shows that blocking the link between PCNA, a protein important for DNA repair, and the androgen receptor (AR), which drives prostate cancer growth, can slow down cancer cell multiplication. This discovery could lead to a new treatment for patients with advanced prostate cancer, particularly those no longer responding to hormone therapy.
Prostate cancer is one of the most common cancers in men. Many patients eventually become resistant to hormone treatment. In this advanced stage, called castration-resistant prostate cancer (CRPC), tumors continue to grow by using either the full-length androgen receptor (AR-FL) or altered versions called AR variants (AR-Vs). This study shows that the interaction between AR and PCNA helps both AR-FL and AR-Vs remain active, supporting cancer cell survival and growth.
The researchers identified a new region in the AR that binds to PCNA. They developed a small peptide, R9-AR-PIP, to mimic this region and block the AR-PCNA connection. They found that this peptide reduced AR's ability to bind DNA and lowered the levels of key genes involved in cancer cell growth. Importantly, the peptide was effective against both types of AR, including the variant forms that are especially challenging in CRPC.
"We identified a second PIP-box (PIP-box592) in the DNA binding domain of AR and found that dihydrotestosterone enhances the binding of full-length AR (AR-FL) but not a constitutively active variant (AR-V7) to PCNA."
They also tested a small molecule, PCNA-I1S, which interferes with PCNA's ability to move to the cell nucleus and interact with AR. This molecule showed similar effects as the peptide, reducing AR activity and stopping cancer cell growth. Together, these findings suggest that targeting PCNA/AR interactions could be a promising strategy to fight CRPC, especially in patients with limited treatment options.
One key result was that both the peptide and the small molecule reduced the levels of cyclin A2, a protein that helps cells divide and is often overexpressed in CRPC. Since this protein is linked to patients' poor outcomes, its reduction could be especially beneficial.
This study improves our understanding of how prostate cancer continues to grow even after hormone treatments fail. By blocking a crucial helper of the androgen receptor, researchers have uncovered a new way to potentially slow or stop the disease. Further studies in animal models are needed, but this approach could lead to more effective treatments for men with advanced prostate cancer.
Continue reading: DOI: https://doi.org/10.18632/oncotarget.28722
