Exosomes are extracellular vesicles of endosomal origin that are released by practically all cell types across metazoans. Exosomes are active vehicles of intercellular communication and can transfer lipids, RNAs, and proteins between different cells, tissues, or organs. Here, we describe a mechanism whereby proteins containing a KFERQ motif pentapeptide are loaded into a subpopulation of exosomes in a process that is dependent on the membrane protein LAMP2A. Moreover, we demonstrate that this mechanism is independent of the ESCRT machinery but dependent on HSC70, CD63, Alix, Syntenin-1, Rab31, and ceramides. We show that the master regulator of hypoxia HIF1A is loaded into exosomes by this mechanism to transport hypoxia signaling to normoxic cells. In addition, by tagging fluorescent proteins with KFERQ-like sequences, we were able to follow the interorgan transfer of exosomes. Our findings open new avenues for exosome engineering by allowing the loading of bioactive proteins by tagging them with KFERQ-like motifs.

The lung is a complex ecosystem of host cells and microbes often disrupted in pathological conditions. Although bacteria have been hypothesized as agents of carcinogenesis, little is known about microbiota profile of the most prevalent cancer subtypes: adenocarcinoma (ADC) and squamous cell carcinoma (SCC). To characterize lung cancer (LC) microbiota a first a screening was performed through a pooled sequencing approach of 16S ribosomal RNA gene (V3-V6) using a total of 103 bronchoalveaolar lavage fluid samples. Then, identified taxa were used to inspect 1009 cases from The Cancer Genome Atlas and to annotate tumor unmapped RNAseq reads. Microbial diversity was analyzed per cancer subtype, history of cigarette smoking and airflow obstruction, among other clinical data. We show that LC microbiota is enriched in Proteobacteria and more diverse in SCC than ADC, particularly in males and heavier smokers. High frequencies of Proteobacteria were found to discriminate a major cluster, further subdivided into well-defined communities’ associated with either ADC or SCC. Here, a SCC subcluster differing from other cases by a worse survival was correlated with several Enterobacteriaceae. Overall, this study provides first evidence for a correlation between lung microbiota and cancer subtype and for its influence on patient life expectancy.

Changes in mucin protein expression and in glycosylation are common features in pre-neoplastic lesions and cancer and are therefore used as cancer-associated markers. De novo expression of intestinal mucin MUC2 and cancer-associated sialyl-Tn antigen are frequently observed in intestinal metaplasia (IM) and gastric cancer. However, despite that these antigens often co-localize, MUC2 has not been demonstrated to be a carrier of sialyl-Tn. By using the in situ proximity ligation assay (in situ PLA), we herein could show that MUC2 is a major carrier of the sialyl-Tn antigen in all IM cases and in most gastric carcinoma cases. The requirement by in situ PLA for the presence of both antigens in close proximity increases the selectivity compared to measurement of co-localization, as determined by immunohistochemistry. Identification of the mucin which is the carrier of a carbohydrate structure offers unique advantages for future development of more accurate diagnostic and prognostic markers.

Chronic Helicobacter pylori infection is recognized as a cause of gastric cancer. H. pylori adhesion to gastric cells is mediated by bacterial adhesins such as sialic acid–binding adhesin (SabA), which binds the carbohydrate structure sialyl–Lewis x. Sialyl–Lewis x expression in the gastric epithelium is induced during persistent H. pylori infection, suggesting that H. pylori modulates host cell glycosylation patterns for enhanced adhesion. Here, we evaluate changes in the glycosylation-related gene expression profile of a human gastric carcinoma cell line following H. pylori infection. We observed that H. pylori significantly altered expression of 168 of the 1,031 human genes tested by microarray, and the extent of these alterations was associated with the pathogenicity of the H. pylori strain. A highly pathogenic strain altered expression of several genes involved in glycan biosynthesis, in particular that encoding β3 GlcNAc T5 (β3GnT5), a GlcNAc transferase essential for the biosynthesis of Lewis antigens. β3GnT5 induction was specific to infection with highly pathogenic strains of H. pylori carrying a cluster of genes known as the cag pathogenicity island, and was dependent on CagA and CagE. Further, β3GnT5 overexpression in human gastric carcinoma cell lines led to increased sialyl–Lewis x expression and H. pylori adhesion. This study identifies what we believe to be a novel mechanism by which H. pylori modulates the biosynthesis of the SabA ligand in gastric cells, thereby strengthening the epithelial attachment necessary to achieve successful colonization.