New Insights into Riluzole for Prostate Cancer Treatment

Prostate Cancer Statistics in Canada

A recent study published in the journal Prostate reveals a potential molecular mechanism by which riluzole, a drug approved for treating amyotrophic lateral sclerosis (ALS), may also be effective against prostate cancer. Prostate cancer ranks as one of the most prevalent non-skin cancers among Canadian males. The Canadian Cancer Society reported approximately 21,300 new cases in 2017, leading to 4,100 deaths. Statistically, one in seven males will face a prostate cancer diagnosis in their lifetime, with one in 29 succumbing to the disease.

Understanding Prostate Cancer’s Hormonal Dependency

Prostate cancer is significantly influenced by androgens, or male hormones. The reduction of these hormones is crucial to obstructing the essential nutritional pathways for the survival of prostate cancer cells. This is typically achieved through surgical castration or by pharmacologically inhibiting the androgen receptor (AR).

However, a concerning challenge arises when patients experience resistance to therapy after an initial response, sometimes developing castration-resistant prostate cancer (CRPC). This condition is characterized by its lack of response to AR inhibition strategies, often due to the emergence of alternative AR forms, such as AR-V7 and mutant ARs.

Research Focus on Overcoming Treatment Resistance

In light of these resistance issues, researchers are intensely exploring innovative strategies to tackle prostate cancer. A key objective is to develop methods that can target both AR and AR-V7 simultaneously, leading to their depletion in cancer cells.

Repurposing Riluzole for Prostate Cancer

Researchers at the Roswell Park Memorial Comprehensive Cancer Center have identified a promising mechanism for how riluzole may be repurposed for prostate cancer treatment. Their findings indicate that riluzole can promote the degradation of AR through pathways related to endoplasmic reticulum (ER) stress and autophagy, effectively reducing AR levels in prostate cancer cells. These results were reported in the journal Prostate.

The study also highlighted the role of the receptor p62, which is essential for guiding proteins toward the autophagic degradation pathway, as it was found to be physically associated with AR. Notably, riluzole demonstrated efficacy in targeting AR-V7 and other mutant AR forms. Additionally, the expression of downstream target genes activated by AR in prostate cancer was significantly diminished.

Significance of the Findings

These discoveries are vital, as the proliferation of prostate cancer is closely tied to AR expression. Numerous studies have underscored the clinical advantages of AR inhibition in stalling prostate cancer growth. Riluzole, which gained FDA approval for ALS treatment in 1995, has already undergone extensive toxicity testing and regulatory review. Consequently, if future results support these findings, the transition to clinical application could proceed swiftly.

Conclusion

The research underscores the potential of riluzole as a dual-targeting agent for both AR and its resistant variants in prostate cancer, marking a significant step forward in addressing treatment challenges in this prevalent disease.

Reference

Wadosky, K. M., Shourideh, M., Goodrich, D. W., & Koochekpour, S. (2018). Riluzole induces AR degradation via endoplasmic reticulum stress pathway in androgen-dependent and castration-resistant prostate cancer cells. Prostate. doi:10.1002/pros.23719