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Abstract Post-translational modifications (PTMs) of the non-histone protein high-mobility group protein B1 (HMGB1) are involved in modulating inflammation and immune responses. Recent studies have implicated that the RNA-binding protein (RBP) Musashi-2 (MSI2) regulates multiple critical biological metabolic and immunoregulatory functions. However, the precise role of MSI2 in regulating PTMs and tumor immunity in colorectal cancer (CRC) remains unclear. Here, we present data indicating that MSI2 potentiates CRC immunopathology in colitis-associated colon cancer (CAC) mouse models, cell lines and clinical specimens, specifically via HMGB1-mediated dendritic cell (DC) maturation and migration, further contributes to the infiltration of CD4+ and CD8+ T cells and inflammatory responses. Under stress conditions, MSI2 can exacerbate the production, nucleocytoplasmic transport and extracellular release of damage-associated molecular patterns (DAMPs)-HMGB1 in CRC cells. Mechanistically, MSI2 mainly enhances the disulfide HMGB1 production and protein translation via direct binding to nucleotides 1403–1409 in the HMGB1 3′ UTR, and interacts with the cytoplasmic acetyltransferase P300 to upregulate its expression, further promoting the acetylation of K29 residue in HMGB1, thus leading to K29-HMGB1 nucleocytoplasmic translocation and extracellular release. Furthermore, blocking HMGB1 activity with glycyrrhizic acid (Gly) attenuates MSI2-mediated immunopathology and immune infiltration in CRC in vitro and in vivo. Collectively, this study suggests that MSI2 may improve the prognosis of CRC patients by reprogramming the tumor immune microenvironment (TIME) through HMGB1-mediated PTMs, which might be a novel therapeutic option for CRC immunotherapy.

Abstract Background Musashi-2 (MSI2) is a critical RNA-binding protein (RBP) whose ectopic expression drives the pathogenesis of various cancers. Accumulating evidence suggests that inducing ferroptosis of tumor cells can inhibit their malignant biological behavior as a promising therapeutic approach. However, it is unclear whether MSI2 regulates cell death in colorectal cancer (CRC), especially the underlying mechanisms and biological effects in CRC ferroptosis remain elusive. Methods Experimental methods including qRT‒PCR, immunofluorescence, flow cytometry, western blot, co-immunoprecipitation, CCK-8, colony formation assay, in vitro cell transwell migration and invasion assays, in vivo xenograft tumor experiments, liver and lung CRC metastasis models, CAC mice models, transmission electron microscopy, immunohistochemistry, histopathology, 4D label-free proteomics sequencing, bioinformatic and database analysis were used in this study. Results Here, we investigated that MSI2 was upregulated in CRC and positively correlated with ferroptosis inhibitor molecules. MSI2 deficiency suppressed CRC malignancy by inhibiting cell proliferation, viability, migration and invasion in vitro and in vivo; and MSI2 deficiency triggered CRC ferroptosis by changing the intracellular redox state (ROS levels and lipid peroxidation), erastin induced cell mortality and viability, iron homeostasis (intracellular total irons and ferrous irons), reduced glutathione (GSH) levels and mitochondrial injury. Mechanistically, through 4D-lable free proteomics analysis on SW620 stable cell lines, we demonstrated that MSI2 directly interacted with p-ERK and MSI2 knockdown downregulated the p-ERK/p38/MAPK axis signaling pathway, which further repressed MAPKAPK2 and HPSB1 phosphorylation, leading to decreased expression of PCNA and Ki67 and increased expression of ACSL4 in cancer cells. Furthermore, HSPB1 could rescue the phenotypes of MSI2 deficiency on CRC ferroptosis in vitro and in vivo. Conclusions This study indicates that MSI2 deficiency suppresses the growth and survival of CRC cells and promotes ferroptosis by inactivating the MAPK signaling pathway to inhibit HSPB1 phosphorylation, which leads to downregulation of PCNA and Ki67 and upregulation of ACSL4 in cancer cells and subsequently induces redox imbalance, iron accumulation and mitochondrial shrinkage, ultimately triggering ferroptosis. Therefore, targeted inhibition of MSI2/MAPK/HSPB1 axis to promote ferroptosis might be a potential treatment strategy for CRC.

RNA-binding proteins (RBPs) mainly contribute to abnormalities in posttranscriptional gene regulation. The RBP Musashi-2, an evolutionarily conserved protein, has been characterized as an oncoprotein in various tumors. However, the prognostic value and potential roles of Musashi-2 in clear cell renal cell carcinoma (ccRCC) have not yet been elucidated. In this study, we found that Musashi-2 was mainly expressed in the normal distal tubular cells and collecting duct cells of the kidneys, while its expression was significantly decreased in ccRCC. And higher expression levels of Musashi-2 indicated better overall survival (OS) in ccRCC. Furthermore, immunohistochemistry demonstrated that PD-L1 expression was negatively correlated with Musashi-2 expression, and Musashi-2 was found to be remarkably correlated with multiple immune cells and immune inhibitors, including CD8+ T cells, CD4+ T cells, regulatory T (Treg) cells, PDCD1, CTLA4, Foxp3, and LAG3. Functional enrichment analysis revealed that Musashi-2 might be involved in ccRCC metabolic reprogramming and immune infiltration and further predicted the therapeutic sensitivity of ccRCC. Taken together, Musashi-2 is a prognostic biomarker for ccRCC patients that may provide novel insights into individualized treatment strategies and guide effective immunotherapy.

A floor supported on long-span beams, which was designed to accommodate bio research instruments, is evaluated for vibration induced by people walking. First, a brief review in vibration criteria is given. The variation of force time histories imposed by people’s feet on supporting objects is also discussed. Both beam and floor finite-element models are then used to simulate the local walking response of the floor mathematically. Footfall forces are applied to the finite-element models via triangular distribution function. A comparison of the time history analysis results with the vibration criteria shows that the floor performs well under people walking. Field measurements were also conducted after the completion of the construction. The measured results show a good correlation with the finite-element analysis results. During the analyses, it was also found that as long as the local floor model covers a structural bay, the boundary conditions of the floor model do not affect the response much. Using an equivalent constant footfall force function can produce similar results compared with those obtained using a more sophisticated force function. [ABSTRACT FROM AUTHOR]