No abstract

Purpose: 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. Experimental Design: 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 in vitro and in vivo. Results: Using different models of HER2 breast cancer cells, we show that anti-GSDMB antibody loaded to nanocapsules has significant and specific effects on GSDMBoverexpressing cancer cells' behavior in ways such as (i) lowering the in vitro 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 in vivo. 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. Conclusions: 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.

Pancreatic cancer stem cells (PaCSCs) drive pancreatic cancer tumorigenesis, chemoresistance and metastasis. While eliminating this subpopulation of cells would theoretically result in tumor eradication, PaCSCs are extremely plastic and can successfully adapt to targeted therapies. In this study, we demonstrate that PaCSCs increase expression of interferon-stimulated gene 15 (ISG15) and protein ISGylation, which are essential for maintaining their metabolic plasticity. CRISPR-mediated ISG15 genomic editing reduces overall ISGylation, impairing PaCSCs self-renewal and their in vivo tumorigenic capacity. At the molecular level, ISG15 loss results in decreased mitochondrial ISGylation concomitant with increased accumulation of dysfunctional mitochondria, reduced oxidative phosphorylation (OXPHOS) and impaired mitophagy. Importantly, disruption in mitochondrial metabolism affects PaCSC metabolic plasticity, making them susceptible to prolonged inhibition with metformin in vivo. Thus, ISGylation is critical for optimal and efficient OXPHOS by ensuring the recycling of dysfunctional mitochondria, and when absent, a dysregulation in mitophagy occurs that negatively impacts PaCSC stemness.

In cirrhosis, intestinal dysbiosis, intestinal barrier impairment, and systemic immune system abnormalities lead to gut bacterial translocation (GBT) and bacterial infection. However, intestinal immune system dysfunction and its contribution to barrier damage are poorly understood. This study correlates immune system dysregulation in the intestines of rats at different stages of CCl4‐induced cirrhosis with barrier function and pathogenic microbiota. The following variables were addressed in the small intestine: intraepithelial lymphocyte (IEL) and lamina propria lymphocyte (LPL) activation status and cytokine production (flow cytometry), cytokine mRNA and protein expression (quantitative real‐time PCR and immunofluorescence), microbiota composition of ileum content (16S recombinant DNA massive sequencing), permeability (fecal albumin loss), and epithelial junctions (immunohistochemistry and immunofluorescence). The intestinal mucosa in rats with cirrhosis showed a proinflammatory pattern of immune dysregulation in IELs and LPLs, which featured the expansion of activated lymphocytes, switch to a T helper 1 (Th1) regulatory pattern, and Th17 reduction. In rats with cirrhosis with ascites, this state was associated with epithelial junction protein disruption, fecal albumin loss, and GBT. Direct correlations (P < 0.01) were observed between elevated interferon gamma (IFNγ)‐expressing T cytotoxic LPLs and fecal albumin and between inflammatory taxa abundance and IFNγ‐producing immune cells in the ileum. Bowel decontamination led to redistributed microbiota composition, reduced proinflammatory activation of mucosal immune cells, normalized fecal albumin levels, and diminished GBT; but there were no modifications in Th17 depletion. Conclusion: The intestinal mucosa of rats with cirrhosis acquires a proinflammatory profile of immune dysregulation that parallels the severity of cirrhosis; this impaired intestinal immune response is driven by gut dysbiosis and leads to disrupted barrier function, promoting GBT.