aiello, i. | Search bioRxiv

bioRxiv2026

A temporally regulated miRNA signature in pancreatic cancer extracellular vesicles disrupts the circadian clock and promotes muscle atrophy

Pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis, aggravated by cachexia, a systemic wasting syndrome whose molecular mediators remain incompletely defined. Circadian disruption is a further hallmark of PDAC, yet a shared mechanistic basis between these two features has not been established. Here we show that the PDAC secretome, and the small extracellular vesicles (sEVs) it carries, are sufficient to disrupt the circadian clock in independent reporter cell lines and in differentiated myotubes, and to induce myotube atrophy. PANC-1 sEV release and miRNA cargo display pronounced time-of-day variation, with the cargo resolving into two functionally distinct pools: a rhythmically secreted subset, whose release is phase-coordinated and which transmits time-of-day information to the recipient tissue, and a constitutively secreted subset that, although non-rhythmic at the source, is itself capable of perturbing the recipient circadian clock. Individual miRNAs drawn from both pools exert distinct and non-redundant effects on circadian period and myotube diameter. Seahorse extracellular flux analysis further reveals that these miRNAs reprogram mitochondrial respiration and substrate utilization along three divergent trajectories, energetic, high-metabolic, and glycolytic, rather than along a single bioenergetic axis. Intersecting the tumor sEV secretome with serum sEV miRNAs from a pancreatic cancer patient cohort and with the miRNA-Seq landscape of 495 PDAC tumors defines a stable, broadly tumor-abundant, patient-detectable miRNA signature that collectively regulates circadian, proteostatic, and cachexia-relevant gene networks. Across these orthogonal datasets, hsa-miR-27b-3p emerges as a node within the rhythmically secreted pool: consistently detected in patient serum, ranked among the top 50 most abundant miRNAs in >90% of these tumors, and individually sufficient to shorten the circadian period, drive myotube atrophy comparable to dexamethasone, and impose an energetic mitochondrial phenotype. Together, these findings identify PDAC sEV miRNAs as temporally organized mediators coupling circadian disruption, muscle bioenergetics, and cachexia-relevant muscle reprogramming.

cell biology↗

bioRxiv2026

White-tailed deer milk exhibits SARS-CoV-2 neutralizing antibodies and synergistic mechanisms that contribute to rapid viral RNA degradation

White-tailed deer (WTD) represent the most significant SARS-CoV-2 wildlife reservoir in North America, yet the role of antiviral mechanisms in vertical transmission remains unexplored. We investigated SARS-CoV-2 antibody responses and viral stability in milk from lactating WTD and humans to characterize species-specific antiviral mechanisms. SARS-CoV-2 neutralizing antibodies were detected in milk and serum in WTD specimens using complementary immunoassays, providing the first evidence of humoral immune responses in wildlife milk. Despite antibody presence indicating prior SARS-CoV-2 exposure, viral RNA was undetectable in all WTD milk samples. This pattern aligns with observations in human milk, where viral RNA was also undetectable both during active infection (when nasal swabs were positive) and during antibody-positive periods following recovery. In vitro stability studies revealed striking species differences: all SARS-CoV-2 variants (A, B.1.1.7, BA.1.1.529) rapidly degraded in WTD milk within 30 min at physiological temperatures, while remaining mostly stable in human milk for up to 60 min. Biochemical characterization identified multifactorial degradation mechanisms in WTD milk, including 5-20 fold elevated mineral concentrations (sodium, magnesium, phosphorus, and potassium), enhanced protease activity, and increased lactoperoxidase levels. Individual mineral supplementation revealed variant-specific susceptibilities, with B.1.1.7 showing pronounced sensitivity to ionic stress. Mechanistic studies demonstrated synergistic effects between elevated ionic concentrations and proteolytic activity, with heat-labile and heat-stable degradation pathways contributing to viral inactivation. These findings reveal that WTD milk possesses intrinsic antiviral properties fundamentally different from human milk, representing an evolutionary adaptation that may impact viral persistence and transmission dynamics in wildlife populations. These findings reveal antiviral mechanisms in WTD milk that represent a previously unrecognized component of pathogen control in wildlife reservoirs, with important implications for understanding wildlife-pathogen interactions and zoonotic risk assessment. Author SummaryWhite-tailed deer (WTD) have become the primary wildlife reservoir for SARS-CoV-2, with millions of infected animals across North America. Despite this significance, the presence of protective antibodies and viral behavior in WTD milk remained unexplored. We collected milk samples from lactating WTD during hunting seasons to investigate whether WTD produce neutralizing antibodies similar to those found in human milk and to examine how the virus behaves in this biological fluid. Our analysis revealed that WTD milk contains antibodies capable of neutralizing SARS-CoV-2. When we compared viral stability between WTD and human milk, we observed that WTD milk rapidly degrades viral genetic material within 30-40 min, while the same virus remains stable in human milk for over an hour. We identified that WTD milk contains mineral concentrations 5-20 times higher than human milk, including elevated levels of sodium, magnesium, and potassium, along with enhanced enzyme activity that breaks down viral components. These findings indicate that WTD milk functions as a protective barrier rather than a transmission route. This has implications for understanding viral persistence in wildlife populations and assessing potential risks to human health. Our work demonstrates that deer milk possesses multiple biological defense mechanisms that may protect offspring from viral infections, contributing to our understanding of wildlife immunity and pandemic preparedness.

microbiology↗