Colistin is considered a last‐resort antibiotic against most gram‐negative bacteria. Recent discoveries of a plasmid‐mediated, transferable mobilized colistin‐resistance gene ( mcr‐1 ) on all continents have heralded the imminent emergence of pan–drug‐resistant superbacteria. The inner‐membrane protein MCR‐1 can catalyze the transfer of phosphoethanolamine (PEA) to lipid A, resulting in colistin resistance. However, little is known about the mechanism, and few drugs exist to address this issue. We present crystal structures revealing the MCR‐1 catalytic domain (cMCR‐1) as a monozinc metalloprotein with ethanolamine (ETA) and d ‐glucose, respectively, thus highlighting 2 possible substrate‐binding pockets in the MCR‐1–catalyzed PEA transfer reaction. Mutation of the residues involved in ETA and d ‐glucose binding impairs colistin resistance in recombinant Escherichia coli containing full‐length MCR‐1. Partial analogs of the substrate are used for cocrystallization with cMCR‐1, providing valuable information about the family of PEA transferases. One of the analogs, ETA, causes clear inhibition of polymyxin B resistance, highlighting its potential for drug development. These data demonstrate the crucial role of the PEA‐ and lipid A–binding pockets and provide novel insights into the structure‐based mechanisms, important drug‐target hot spots, and a drug template for further drug development to combat the urgent, rising threat of MCR‐1–mediated antibiotic resistance.—Wei, P., Song, G., Shi, M., Zhou, Y., Liu, Y., Lei, J., Chen, P., Yin, L. Substrate analog interaction with MCR‐1 offers insight into the rising threat of the plasmid‐mediated transferable colistin resistance. FASEB J. 32, 1085–1098 (2018). www.fasebj.org

Intrahepatic cholangiocarcinoma (ICC) is a malignant tumor with a poor prognosis, predominantly CA19-9 positive. High CA19-9 levels correlate with increased aggressiveness and worse outcomes. This study employs multi-omics analysis to reveal molecular features and identify therapeutic targets of CA19-9 positive ICC, aiming to support individualized treatment. Data from seven clinical cohorts, two whole-exome sequencing cohorts, six RNA sequencing/microarray cohorts, one proteomic cohort, 20 single-cell RNA sequencing samples, and one spatial transcriptome sample were analyzed. Key findings were validated on tissue microarrays from 52 ICC samples. CA19-9 positive ICC exhibited poorer OS (median 24.1 v.s. 51.5 months) and RFS (median 11.7 v.s. 28.2 months) compared to negative group (all P < 0.05). Genomic analysis revealed a higher KRAS mutation frequency in the positive group and a greater prevalence of IDH1/2 mutations in the negative group (all P < 0.05). Transcriptomic analysis indicated upregulated glycolysis pathways in CA19-9 positive ICC. Single-cell analysis identified specific glycolysis-related cell subclusters associated with poor prognosis, including Epi_SLC2A1, CAF_VEGFA, and Mph_SPP1. Higher hypoxia in the CA19-9 positive group led to metabolic reprogramming and promoted these cells’ formation. These cells formed interactive communities promoting epithelial-mesenchymal transition (EMT) and angiogenesis. Drug sensitivity analysis identified six potential therapeutic drugs. This study systematically elucidated the clinical, genomic, transcriptomic, and immune features of CA19-9 positive ICC. It reveals glycolysis-associated cellular communities and their cancer-promoting mechanisms, enhancing our understanding of ICC and laying the groundwork for individualized therapeutic strategies.

Significance: Tumor vaccines using modified self-antigens that structurally enhance T cell receptor–peptide–major histocompatibility complex interactions greatly improve a T cell protective response against the tumor’s unmodified self-antigen. X-ray crystal structures of these interactions explain how the native and modified peptides can interact with the same T cell receptor, but with different affinities and abilities to drive T cell proliferation and differentiation.

Cancer vaccines, aimed at evolving the human immune system to eliminate tumor cells, have long been explored as a method of cancer treatment with significant clinical potential. Traditional delivery systems face significant challenges in directly targeting tumor cells and delivering adequate amounts of antigen due to the hostile tumor microenvironment. Emerging evidence suggests that certain bacteria naturally home in on tumors and modulate antitumor immunity, making bacterial vectors a promising vehicle for precision cancer vaccines. Live bacterial vehicles offer several advantages, including tumor colonization, precise drug delivery, and immune stimulation, making them a compelling option for cancer immunotherapy. In this review, we explore the mechanisms of action behind living bacteria-based vaccines, recent progress in popular bacterial chassis, and strategies for specific payload delivery and biocontainment to ensure safety. These approaches will lay the foundation for developing an affordable, widely applicable cancer vaccine delivery system. This review also discusses the challenges and future opportunities in harnessing bacterial-based vaccines for enhanced therapeutic outcomes in cancer treatment.