CYD0281, a Bcl-2 BH4 domain antagonist, inhibits tumor angiogenesis and breast cancer tumor growth

Background: B-cell lymphoma 2 (Bcl-2) family proteins are key regulators of apoptosis, which possess four conserved Bcl-2 homologies (BH) domains. Among the BH domains, the BH3 domain is considered as a potent 'death domain' while the BH4 domain is required for anti-apoptotic activity. Bcl-2 can be converted to a pro-apoptotic molecule through the removal or mutation of the BH4 domain. Bcl-2 is considered as an inducer of angiogenesis, which can promote tumor vascular network formation and further afford nutrients and oxygen to promote tumor progression. However, whether disrupting the function of the BH4 domain to convert Bcl-2 into a pro-apoptotic molecule could make Bcl-2 possess the potential for anti-angiogenic therapy remains to be defined.

Methods: CYD0281 was designed and synthesized according to the lead structure of BDA-366, and its function on inducing a conformational change of Bcl-2 was further evaluated via immunoprecipitation (IP) and immunofluorescence (IF) assays. Moreover, the function of CYD0281 on apoptosis of endothelial cells was analyzed via cell viability, flow cytometry, and western blotting assays. Additionally, the role of CYD0281 on angiogenesis in vitro was determined via endothelial cell migration and tube formation assays and rat aortic ring assay. Chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) models, breast cancer cell xenograft tumor on CAM and in mouse models as well as the Matrigel plug angiogenesis assay were used to explore the effects of CYD0281 on angiogenesis in vivo.

Results: We identified a novel potent small-molecule Bcl-2-BH4 domain antagonist, CYD0281, which exhibited significant anti-angiogenic effects both in vitro and in vivo, and further inhibited breast cancer tumor growth. CYD0281 was found to induce conformational changes in Bcl-2 through the exposure of the BH3 domain and convert Bcl-2 from an anti-apoptotic molecule into a cell death inducer, thereby resulting in the apoptosis of vascular endothelial cells.

Conclusions: This study has revealed CYD0281 as a novel Bcl-2-BH4 antagonist that induces conformational changes of Bcl-2 to convert to a pro-apoptotic molecule. Our findings indicate that CYD0281 plays a crucial role in anti-angiogenesis and may be further developed as a potential anti-tumor drug candidate for breast cancer. This work also provides a potential anti-angiogenic strategy for breast cancer treatment.

 

Comments:

This is a fascinating study! It seems like CYD0281 could potentially be a game-changer in anti-angiogenic therapy for breast cancer. By targeting the BH4 domain of Bcl-2 and inducing a conformational change that converts it from an anti-apoptotic to a pro-apoptotic molecule, CYD0281 shows promise in inhibiting tumor vascular network formation and subsequently hindering tumor progression.

The combination of in vitro and in vivo experiments, including cell viability assays, immunoprecipitation, immunofluorescence, and angiogenesis assays in different models, lends strong support to the efficacy of CYD0281 in not only inhibiting angiogenesis but also suppressing breast cancer tumor growth.

The ability of CYD0281 to induce conformational changes in Bcl-2, exposing the BH3 domain and triggering apoptosis in vascular endothelial cells, showcases its potential as a novel therapeutic agent for breast cancer treatment.

The findings of this study are significant not just in identifying CYD0281 as a potent Bcl-2-BH4 antagonist but also in laying the groundwork for potential future drug development and anti-angiogenic strategies in breast cancer therapy. This research could pave the way for exploring similar approaches in other cancer types or expanding the understanding of Bcl-2 family proteins' roles in tumor angiogenesis.

The results presented here have exciting implications for advancing targeted therapies in breast cancer treatment and underscore the potential of CYD0281 as a promising candidate for further preclinical and clinical investigations.