Intracellular Delivery of an Antibody Targeting Gasdermin-B Reduces HER2 Breast Cancer Aggressiveness.

Abstract

Gasdermin B (GSDMB) overexpression/amplification occurs in about 60% of HER2 breast cancers, where it promotes cell migration, resistance to anti-HER2 therapies, and poor clinical outcome. Thus, we tackle GSDMB cytoplasmic overexpression as a new therapeutic target in HER2 breast cancers. We have developed a new targeted nanomedicine based on hyaluronic acid-biocompatible nanocapsules, which allow the intracellular delivery of a specific anti-GSDMB antibody into HER2 breast cancer cells both <i>in vitro</i> and <i>in vivo</i>. Using different models of HER2 breast cancer cells, we show that anti-GSDMB antibody loaded to nanocapsules has significant and specific effects on GSDMB-overexpressing cancer cells' behavior in ways such as (i) lowering the <i>in vitro</i> cell migration induced by GSDMB; (ii) enhancing the sensitivity to trastuzumab; (iii) reducing tumor growth by increasing apoptotic rate in orthotopic breast cancer xenografts; and (iv) diminishing lung metastasis in MDA-MB-231-HER2 cells <i>in vivo</i>. Moreover, at a mechanistic level, we have shown that AbGB increases GSDMB binding to sulfatides and consequently decreases migratory cell behavior and may upregulate the potential intrinsic procell death activity of GSDMB. Our findings portray the first evidence of the effectiveness and specificity of an antibody-based nanomedicine that targets an intracellular oncoprotein. We have proved that intracellular-delivered anti-GSDMB reduces diverse protumor GSDMB functions (migration, metastasis, and resistance to therapy) in an efficient and specific way, thus providing a new targeted therapeutic strategy in aggressive HER2 cancers with poor prognosis.