Molecular Profiling of Stromal Components in Prostate Cancer: Leveraging LCM and RPPA to examine Clinical Outcomes

Introduction: Prostate cancer remains a significant health challenge, necessitating advanced methodologies for accurate diagnosis and understanding of its molecular makeup. The tumor microenvironment, particularly the stroma, plays a critical role in cancer progression and metastasis. In this study, we focus on characterizing the activation of the immune and DNA damage repair signaling pathways within the stromal compartment of prostate cancer tissue from a patient undergoing treatment with Pembrolizumab. By analyzing biopsies obtained at various stages of the treatment plan, we investigate the protein signaling changes in the microenvironment throughout the course of treatment. Methodology: We utilized Laser Capture Microdissection (LCM) technology to isolate stroma cells from prostate cancer tissue samples. A total of nine biopsies were obtained at various stages of the treatment plan. Following microdissection, the collected cells underwent analysis using Reverse Phase Protein Microarray (RPPA) technology, which allowed for the quantification of protein expression levels and the identification of signaling pathway alterations. Data from RPPA were analyzed using MicroVigene software, which facilitated data processing and interpretation. These methodologies collectively enabled an investigation of the stroma signaling pathways in prostate cancer, potentially identifying biomarkers for improved diagnosis. Conclusion: Our analysis of the stroma cells revealed several markers exhibiting elevated activation levels, including FoxP3, MSH2, mTOR S2448, Histone H2A.X S139, B7-H4, CD3zeta, HLA-DR, HLA-DR-DP-DQ-DX, Granzyme B, and CD31-PECAM1. These elevated values may indicate higher activity from the patient’s autoimmune response. Conversely, the markers Chk1_S345, STAT1_Y701, and PDL122C3 were not elevated, implying lower activity levels. Further research is needed to confirm our results.