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The origin of breast cancer, whether primary or recurrent, is unknown. Here, we show that invasive breast cancer cells exposed to hypoxia release small extracellular vesicles (sEVs) that disrupt the differentiation of normal mammary epithelia, expand stem and luminal progenitor cells, and induce atypical ductal hyperplasia and intraepithelial neoplasia. This was accompanied by systemic immunosuppression with increased myeloid cell release of the alarmin S100A9 and oncogenic traits of epithelial-mesenchymal transition, angiogenesis, and local and disseminated luminal cell invasion in vivo. In the presence of a mammary gland driver oncogene (MMTV-PyMT), hypoxic sEVs accelerated bilateral breast cancer onset and progression. Mechanistically, genetic or pharmacologic targeting of hypoxia-inducible factor-1[alpha] (HIF1[alpha]) packaged in hypoxic sEVs or homozygous deletion of S100A9 normalized mammary gland differentiation, restored T cell function, and prevented atypical hyperplasia. The transcriptome of sEV-induced mammary gland lesions resembled luminal breast cancer, and detection of HIF1[alpha] in plasma circulating sEVs from luminal breast cancer patients correlated with disease recurrence. Therefore, sEV-HIF1[alpha] signaling drives both local and systemic mechanisms of mammary gland transformation at high risk for evolution to multifocal breast cancer. This pathway may provide a readily accessible biomarker of luminal breast cancer progression., Introduction Breast cancer is the second most common malignancy diagnosed in women, resulting in over 43,000 deaths a year in the United States alone (1). Despite progress in early diagnosis [...]

This document is an editorial published in Frontiers in Endocrinology titled "Double-edged swords: important factors connecting metabolic disorders and cancer development -- from basic research to translational applications, volume II." The editorial discusses the intersection between metabolic dysfunction and cancer development, highlighting new challenges and opportunities in this field. It covers various topics such as drug resistance in cancer therapy, strategies to overcome resistance in hepatocellular carcinoma, the role of immunity and metabolism in liver steatosis-driven carcinogenesis, the link between metabolic factors and thyroid cancer, the role of metabolites in kidney tubulogenesis, the role of glucose metabolism in human diseases, genetic alterations in metabolic enzymes and their contribution to diseases, the potential therapeutic target of MG53 in cancer, the potential of niclosamide in cancer therapy, and the role of innate immunity and inflammation in differential susceptibilities to metabolic disorders and cancer among racial populations. The editorial concludes by emphasizing the ongoing discussion and learning about the links between metabolic functions and cancer, from basic science to translational applications. [Extracted from the article]

Mitochondria are signaling organelles implicated in cancer, but the mechanisms are elusive. Here, we show that Parkin, an E3 ubiquitination (Ub) ligase altered in Parkinson's disease, forms a complex with the regulator of cell motility, Kindlin-2 (K2), at mitochondria of tumor cells. In turn, Parkin ubiquitinates Lys581 and Lys582 using Lys48 linkages, resulting in proteasomal degradation of K2 and shortened half-life from -5 h to -1.5 h. Loss of K2 inhibits focal adhesion turnover and ß1 integrin activation, impairs membrane lamellipodia size and frequency, and inhibits mitochondrial dynamics, altogether suppressing tumor cell-extracellular matrix interactions, migration, and invasion. Conversely, Parkin does not affect tumor cell proliferation, cell cycle transitions, or apoptosis. Expression of a Parkin Ub-resistant K2 Lys581Ala/Lys582Ala double mutant is sufficient to restore membrane lamellipodia dynamics, correct mitochondrial fusion/fission, and preserve single-cell migration and invasion. In a 3D model of mammary gland developmental morphogenesis, impaired K2 Ub drives multiple oncogenic traits of EMT, increased cell proliferation, reduced apoptosis, and disrupted basal-apical polarity. Therefore, deregulated K2 is a potent oncogene, and its Ub by Parkin enables mitochondria-associated metastasis suppression. [ABSTRACT FROM AUTHOR]

The activation of innate immunity and associated interferon (IFN) signaling have been implicated in cancer, but the regulators are elusive and a link to tumor suppression undetermined. Here, we found that Parkin, an E3 ubiquitin ligase altered in Parkinson's Disease was epigenetically silenced in cancer and its re-expression by clinically approved demethylating therapy stimulated transcription of a potent IFN response in tumor cells. This pathway required Parkin E3 ubiquitin ligase activity, involved the subcellular trafficking and release of the alarmin High Mobility Group Box 1 (HMGB1) and was associated with inhibition of NFκB gene expression. In turn, Parkin-expressing cells released an IFN secretome that upregulated effector and cytotoxic CD8 T cell markers, lowered the expression of immune inhibitory receptors, TIM3 and LAG3, and stimulated high content of the self-renewal/stem cell factor, TCF1. Parkin-induced CD8 T cells selectively accumulated in the microenvironment and inhibited transgenic and syngeneic tumor growth, in vivo. Therefore, Parkin is an epigenetically regulated activator of innate immunity and dual mode tumor suppressor, inhibiting intrinsic tumor traits of metabolism and cell invasion, while simultaneously reinvigorating CD8 T cell functions in the microenvironment.

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Glioblastoma (GBM), a very aggressive and incurable tumor, often results from constitutive activation of EGFR (epidermal growth factor receptor) and of phosphoinositide 3-kinase (PI3K). To understand the role of autophagy in the pathogenesis of glial tumors in vivo , we used an established Drosophila melanogaster model of glioma based on overexpression in larval glial cells of an active human EGFR and of the PI3K homolog Pi3K92E/Dp110 . Interestingly, the resulting hyperplastic glia express high levels of key components of the lysosomal-autophagic compartment, including vacuolar-type H + -ATPase (V-ATPase) subunits and ref(2)P (refractory to Sigma P), the Drosophila homolog of SQSTM1/p62. However, cellular clearance of autophagic cargoes appears inhibited upstream of autophagosome formation. Remarkably, downregulation of subunits of V-ATPase, of Pdk1 , or of the Tor (Target of rapamycin) complex 1 (TORC1) component raptor prevents overgrowth and normalize ref(2)P levels. In addition, downregulation of the V-ATPase subunit VhaPPA1-1 reduces Akt and Tor-dependent signaling and restores clearance. Consistent with evidence in flies, neurospheres from patients with high V-ATPase subunit expression show inhibition of autophagy. Altogether, our data suggest that autophagy is repressed during glial tumorigenesis and that V-ATPase and MTORC1 components acting at lysosomes could represent therapeutic targets against GBM.