In a significant advancement for the field of oncology, researchers at the University of Michigan Rogel Cancer Center have identified a specific gene that serves as a primary driver in the development of aggressive, treatment-resistant prostate cancer. The discovery not only sheds light on the biological mechanisms that allow cancer cells to evade standard therapies but also points toward a potential treatment strategy using an existing class of drugs. By targeting the protein products of this gene indirectly, clinicians may soon have a new way to combat the most lethal forms of the disease.
Prostate cancer remains one of the most common malignancies among men, and while many cases are slow-growing and highly treatable, a subset of patients develops aggressive forms that stop responding to conventional medicine. For decades, the cornerstone of treatment for advanced prostate cancer has been androgen deprivation therapy. This approach works by blocking the androgen receptor, a protein that prostate cancer cells typically rely on to grow and survive. However, the cancer often finds a way to adapt.
"Patients whose prostate tumors lose reliance on the androgen receptor do poorly. Our results suggest a therapeutic approach for patients whose tumors have undergone that shift," said the study’s senior author, Joshi J. Alumkal, M.D., the Wicha Family Professor of Oncology at the University of Michigan Rogel Cancer Center.
The study, which was recently published in the Journal of Clinical Investigation, focuses on a phenomenon known as lineage plasticity. This is a process by which cancer cells essentially "shapeshift," moving away from their original identity as glandular prostate cells—which are dependent on the androgen receptor—and taking on new identities that allow them to thrive even when the androgen receptor is inhibited. This transition is not an overnight event but rather a continuum, where cells gradually lose their original characteristics and adopt alternate survival mechanisms.
Led by Zhi Duan, Ph.D., the research team sought to uncover the specific factors that trigger this dangerous transition. Through an exhaustive analysis of patient tumor biopsies, the researchers identified a gene called PROX1 as a major culprit. PROX1 is a transcription factor, a type of protein responsible for dictating cell identity in both healthy development and the progression of disease. The team observed that as prostate cancer cells began to move away from their dependence on the androgen receptor, the expression of PROX1 increased significantly.
The investigation into PROX1 began with a close look at the molecular landscape of tumors that had already undergone lineage plasticity. When comparing these aggressive samples to more typical prostate cancers, PROX1 emerged as the most highly upregulated gene. To confirm these findings, the researchers examined hundreds of patient tumors across the entire spectrum of lineage plasticity. They discovered that PROX1 serves as an early marker of this shift, appearing even before the cancer has fully transformed into its most resistant state.
