Autophagy as a modulator and target in prostate cancer

Autophagy, or “self eating,” is an adaptive process that helps cells cope with metabolic, toxic, and even infectious stressors. While the adaptive capability of autophagy is generally beneficial, autophagy can also facilitate enhanced nutrient utilization and improved growth characteristics in cancer cells. Moreover, autophagy can promote greater cellular robustness in the context of therapeutic intervention. This has proven to be the case in advanced prostate cancer, where preclinical data largely supports that autophagy facilitates both disease progression and therapeutic resistance. Notably, androgen deprivation therapy, taxane-based chemotherapy, targeted kinase inhibition, and nutrient restriction all induce significant cellular distress. Autophagy is subsequently up-regulated through core metabolic regulatory signaling cascades (i.e. AMPK, PI3K, and mTOR), and more favorable growth and nutrient conditions are established. Current research also demonstrates that when the autophagic machinery is inhibited, greater cell killing and tumor responsiveness can be obtained. In this review, we will cover current prostate cancer treatments associated with alterations in autophagy; data supporting autophagic modulation with added emphasis on alterations occurring within prostate cancer models; and finally, research supporting adjuvant autophagic modulation with current prostate cancer treatment paradigms