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PubMed2026

Adaptive proteomic remodeling and eNOS upregulation in luminal endothelium and perivascular adipose tissue of patent saphenous vein grafts after CABG.

OBJECTIVE: Long-term patency of saphenous vein grafts (SVGs) remains a significant challenge in coronary artery bypass grafting (CABG). The biological factors underlying successful human grafts are poorly understood. We aimed to characterize the structural and molecular features associated with successful graft function. METHODS: Patent and occluded SVG and internal thoracic artery (ITA) grafts were obtained from explanted hearts of CABG patients undergoing heart transplantation for end-stage heart failure not attributable to graft failure, along with freshly harvested ITA and SVG controls. Samples underwent histomorphological analysis, immunohistochemistry (IHC), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics. RESULTS: Patent ITA (ITA-P) showed minimal intimal hyperplasia with medial reinforcement, whereas patent SVGs (SVG-P) had organized, α-smooth muscle actin (αSMA)-positive myofibroblast-rich neointima. Endothelial nitric oxide synthase (eNOS) was markedly upregulated in patent grafts at two sites-the luminal endothelium and adventitial microvessels within perivascular adipose tissue (PVAT)-and lost at both sites in occluded SVG (SVG-O). Adventitial CD31-positive microvessels were significantly increased in patent grafts. Proteomically, ITA-P and SVG-P shared a largely common adaptive proteome enriched in translation, RNA processing, and extracellular matrix (ECM) organization, with shared upstream activation of NR4A3, EGFR, and STAT1, and conduit-specific signatures (IGF-1/RUNX2 in ITA-P; RETN/SRC/PTGES in SVG-P). PTGES was strongly expressed in the adventitia of SVG-P. CONCLUSIONS: Patent arterial and venous bypass grafts exhibited a shared adaptive phenotype characterized by dual-site upregulation of eNOS in both the luminal endothelium and the perivascular microvessels/PVAT. In SVG-P, PTGES was co-upregulated alongside eNOS, indicating a mechanistic link between the proteomic and IHC findings. These findings highlight the perivascular compartment as a site of adaptive, eNOS-associated changes in patent vein grafts.

Humans↗
PubMed2026

A novel peptide encoded by circTLL1 drives osimertinib resistance in lung cancer by modulating the NT5C2/Ras/PI3K axis.

BACKGROUND: Acquired resistance to osimertinib, a third-generation EGFR tyrosine kinase inhibitor, remains a major clinical challenge in the treatment of non-small cell lung cancer (NSCLC). Although circular RNAs (circRNAs) have been increasingly implicated in drug resistance, most studies have focused on their canonical role as microRNA sponges, while their capacity to encode functional micropeptides remains largely unexplored. This study aimed to identify novel circRNAs involved in osimertinib resistance and to characterize their regulatory functions at the protein level. METHODS: Osimertinib-resistant (OR) NSCLC cell lines were established and validated. High-throughput RNA sequencing was performed to compare the circRNA expression profiles between parental and OR cells. The function of the candidate circRNA was assessed through a series of in vitro and in vivo experiments, including cell viability assays, apoptosis analysis, and xenograft mouse models. Mechanistic investigations involved mass spectrometry, co-immunoprecipitation and western blotting to explore its protein-coding potential and downstream signaling pathways. RESULTS: We identified a novel circRNA, termed circTLL1, that was stably and significantly upregulated in OR-NSCLC cells. Functionally, overexpression of circTLL1 promoted osimertinib resistance, whereas its knockdown restored drug sensitivity both in vitro and in vivo. Mechanistically, we discovered that circTLL1 harbors an open reading frame (ORF) that is translated into a novel 90-amino-acid protein, which we designated circTLL1-90aa. Further investigation revealed that circTLL1-90aa directly interacts with and promotes the degradation of 5'-nucleotidase, cytosolic II (NT5C2), thereby uncoupling nucleotide metabolism from its normal regulatory constraints. The consequent downregulation of NT5C2 leads to elevated GTP levels and leading to the sustained activation of the downstream Ras/PI3K/AKT signaling pathway. CONCLUSION: Our findings unveil a previously unrecognized circRNA/micropeptide/metabolism cascade underlying osimertinib resistance. The identification of the circTLL1-90aa/NT5C2/Ras/PI3K axis not only expands the functional repertoire of the non-coding genome but also provides new insights into the complexity of drug resistance. Given its selective upregulation in resistant cells, circTLL1-90aa holds promise both as a predictive biomarker for treatment stratification and as an actionable therapeutic target, offering a novel strategy to overcome osimertinib resistance in NSCLC patients.

Pyrimidines↗