Comparative efficacy of epigallocatechin gallate and its nano-formulation in prostate cancer 3D spheroids model

Background: Prostate cancer (PCa) remains one of the clinically relevant pathologies that needs pragmatic and effective treatment approaches. The current study aimed to evaluate the anticancer potential of epigallocatechin gallate (EGCG) and EGCG-loaded nanoparticles (EGCG NP) for the treatment of prostate cancer in in-vitro 3D spheroid model.Methods: The EGCG NPs was synthesized by using polymeric method as reported in our previous study. A 3D spheroid assay was conducted using human prostate specific cell lines (PC3 and 22Rv1) cultured on poly-HEMA-covered plates at different time points. Once formed, the spheroids were treated with either EGCG alone or with EGCG NPs continuously for 6 days. Simultaneously, specific controls were also taken for comparison purpose. CellROX dye was used to quantitate the formation of reactive oxygen species (ROS) in response to EGCG and EGCG NPs to 22Rv1 and PC3, 3D spheroids. The treated spheroids were also evaluated to measure modulation in mitochondrial membrane potential and the quantification of apoptotic and live cells using a flow cytometer.Results: The spheroid sizes of both studied cell lines were found to be significantly (p < 0.05) reduced after the treatment with EGCG and its nanoformulation. The significant increase in ROS formation was observed in PC3 cells in response to EGCG and EGCG-NPs treatment. However, no significant change in ROS formation was observed in 22Rv1 cells. Similarly, both compounds (EGCG and EGCG NPs) did not show any significant changes in mitochondrial membrane potential in 22Rv1 and PC3 spheroids. Interestingly, EGCG treatment showed a significant change between live and apoptotic cells in both 22Rv1 and PC3 spheroids but its nanoformulation didn't show any significant change in the number of apoptotic and live cells. Our study observed a significant anticancer potential of EGCG and EGCG NPs at clinically relevant doses highlighting the possible advantage of 3D spheroid model specifically in our studied cancer cells. However, further preclinical in vivo studies are recommended in a suitable model to decipher our in vitro data and exploit EGCG and EGCG NPs against prostate cancer.Conclusion: Our results indicate the anticancer efficacy of EGCG and EGCG NPs in 3D spheroids of PCa cell lines.