The treatment landscape for patients with prostate cancer, especially individuals with advanced disease, has dramatically changed in recent years. However, aside from drug or hormonal therapies, other targets to treat prostate cancer are still necessary to prolong life and slow the progression of this potentially lethal disease. A recent study in The American Journal of Pathology found that inhibition of the sterol regulatory element of binding (SREB) may reinduce sensitivity to docetaxel, commonly used to treat prostate and other cancers. These findings show promise to improve the efficacy of docetaxel-based chemotherapy in patients with prostate cancer.
Co-lead investigator Maximilian P. Brandt, MD, of the Department of Urology and Pediatric Urology, Mainz University Medical Center, Germany, explained: “Prostate cancer is the most common cancer in men, and it remains a clinical challenge to find the right treatment for patients with metastatic disease. It is crucial to develop new therapeutic strategies and find new targets to optimize treatment. Knowing that every patient with metastatic prostate cancer who receives a first line of systemic treatment will eventually develop therapy resistance, eg, against docetaxel or hormones, makes this research highly interesting and necessary.”
Treatment Options
Over the past decade, treatment options for patients with metastatic prostate cancer have dramatically increased with improved disease control by prolonging progression-free survival and overall survival. Docetaxel is one of the most established chemotherapy regimens for prostate cancer and remains a cornerstone in the treatment of patients with prostate cancer. Combining docetaxel with second-generation hormonal therapy is a novel treatment approach, with recent studies showing improved progression-free and overall survival. However, the efficacy of chemotherapy is restricted by the development of resistance, which represents a significant limitation in clinical practice.
Investigators performed RNA sequencing in docetaxel-resistant prostate cancer cell models after treatment with a combination of docetaxel and mifepristone. This treatment significantly reduced cancer cell viability. RNA sequencing revealed sterol regulatory element of binding transcription factor 1 (SREBF-1), a transcription factor of cholesterol and lipid biosynthesis, as a significantly downregulated target. This is a central cellular regulator involved in docetaxel-resistant prostate cancer. Specific inhibition of cholesterol and lipid biosynthesis reinduced sensitivity to docetaxel. Furthermore, researchers were able to show that SREBPs are increasingly expressed in metastatic prostate cancer, which they found in a specific tissue microarray from tumor tissue from patients with advanced prostate cancer.
Co-lead investigator Martin Puhr, PhD, of the Department of Urology, Medical University of Innsbruck, Austria, noted: “Our results support the idea that SREBPs are essential regulators of cell survival and susceptibility to docetaxel in advanced and metastatic prostate cancer, affecting prostate cancer aggressiveness and docetaxel resistance. Our data provide further evidence that inhibiting cholesterol and lipid biosynthesis might provide a clinically meaningful rationale for increasing the efficacy of prostate cancer therapies and in specific, drug-resistant prostate cancer.”
Disclosure: For full disclosures of all study authors, visit The American Journal of Pathology.
