Heat Shock Protein 27 Enhances SUMOylation of Heat Shock Protein B8 to Accelerate the Progression of Breast Cancer

Heat shock proteins (HSPs) are emerging as valuable potential molecular targets in breast cancer therapy owing to their diverse functions in cancer cells. This study investigated the potential role of heat shock protein 27 (HSP27, also known as HSPB1) in breast cancer through heat shock protein B8 (HSPB8). The correlation between HSP27 and HSPB8 was identified by using co-immunoprecipitation, immunoprecipitation, and SUMOylation assays. Through gain- and loss-of-function approaches in MCF-7 cells, the effect of HSP27 on HSPB8 expression, SUMOylation level, and protein stability of HSPB8, as well as on cell proliferation, migration, and stemness, was elucidated. A mouse xenograft model of breast cancer cells was established to verify the function of HSP27 in vivo. Results indicate that HSP27 and HSPB8 were highly expressed in breast cancer tissues and MCF-7 cells. HSP27 was also found to induce the SUMOylation of HSPB8 at the 106 locus and subsequently increased its protein stability, which resulted in accelerated proliferation, migration, and stemness of breast cancer cells in vitro along with increased tumor metastasis of breast cancer in vivo. However, these results could be reversed by the knockdown of HSPB8. Overall, HSP27 induces SUMOylation of HSPB8 to promote HSPB8 expression, thereby endorsing proliferation and metastasis of breast cancer cells. This study may provide insight for the development of new targets for breast cancer.