The AKT/BCL-2 Axis Mediates Survival of Uterine Leiomyoma in a Novel 3D Spheroid Model

Abstract

A deeper understanding of the pathways that drive uterine leiomyoma (ULM) growth and survival requires model systems that more closely mimic the in vivo tumors. This would provide new insights into developing effective therapeutic strategies for these common benign tumors of childbearing-aged women. In this study, we examined the role of BCL-2 in mediating ULM survival in the context of increased protein kinase B (AKT) and oxidative stress using a three-dimensional (3D), spheroid-based model that more closely resembles the native ULM tumor microenvironment. Human primary cells from matched myometrium (MM) and ULM tissues were used to establish spheroid cultures in vitro. Histological and immunohistochemical methods were used to assess the spheroid architecture and characteristics. Viability assays for 3D cultures were used to evaluate their response to BH3 mimetics and the superoxide inducer, paraquat (PQ). Primary MM and ULM cells formed spheroids in culture. Notably, ULM spheroids exhibited low proliferation, increased oxidative stress, and secretion of interstitial collagen. Knockdown studies revealed that AKT sustained BCL-2 expression in ULM. The targeting of BCL-2 with BH3 mimetics effectively reduced viability and induced apoptosis in a subset of ULM spheroids. ULM spheroids that did not respond to BH3 mimetics alone responded to combination treatment with PQ. In conclusion, BCL-2 mediates AKT survival of ULM, providing compelling evidence for further evaluation of BH3 mimetics for ULM treatment. ULM spheroids recapitulated intrinsic features of the native ULM tumor microenvironment and can be used as a model for preclinical testing of potential therapeutic options for ULM.