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The two T cell inhibitory receptors PD-1 and TIM-3 are co-expressed during exhausted T cell differentiation, and recent evidence suggests that their crosstalk regulates T cell exhaustion and immunotherapy efficacy; however, the molecular mechanism is unclear. Here we show that PD-1 contributes to the persistence of PD-1 + TIM-3 + T cells by binding to the TIM-3 ligand galectin-9 (Gal-9) and attenuates Gal-9/TIM-3-induced cell death. Anti-Gal-9 therapy selectively expands intratumoral TIM-3 + cytotoxic CD8 T cells and immunosuppressive regulatory T cells (T reg cells). The combination of anti-Gal-9 and an agonistic antibody to the co-stimulatory receptor GITR (glucocorticoid-induced tumor necrosis factor receptor-related protein) that depletes T reg cells induces synergistic antitumor activity. Gal-9 expression and secretion are promoted by interferon β and γ, and high Gal-9 expression correlates with poor prognosis in multiple human cancers. Our work uncovers a function for PD-1 in exhausted T cell survival and suggests Gal-9 as a promising target for immunotherapy. Galectin-9 regulates several cellular processes including TIM-3-mediated T cell death. Here the authors show that co-expressed PD-1 protects TIM-3 + T cells from galectin-9-induced cell death and that anti-galectin-9 in combination with GITR agonism promotes an anti-tumor immune response.

Glycosylation of immune receptors and ligands, such as T cell receptor and coinhibitory molecules, regulates immune signaling activation and immune surveillance. However, how oncogenic signaling initiates glycosylation of coinhibitory molecules to induce immunosuppression remains unclear. Here we show that IL-6-activated JAK1 phosphorylates programmed death-ligand 1 (PD-L1) Tyr112, which recruits the endoplasmic reticulum-associated N-glycosyltransferase STT3A to catalyze PD-L1 glycosylation and maintain PD-L1 stability. Targeting of IL-6 by IL-6 antibody induced synergistic T cell killing effects when combined with anti-T cell immunoglobulin mucin-3 (anti-Tim-3) therapy in animal models. A positive correlation between IL-6 and PD-L1 expression was also observed in hepatocellular carcinoma patient tumor tissues. These results identify a mechanism regulating PD-L1 glycosylation initiation and suggest the combination of anti-IL-6 and anti-Tim-3 as an effective marker-guided therapeutic strategy.

Epidermal growth factor receptor, the product of a human oncogene, suppresses the maturation of specific tumour-suppressor-like microRNAs in response to hypoxic stress through phosphorylation of argonaute 2. Impact of hypoxia on miRNAs MicroRNA-mediated regulation of gene expression occurs during response to stresses such as hypoxia, a condition found in the centre of a solid tumour. Mien-Chie Hung and colleagues show that the oncogene product EGFR (epidermal growth factor receptor) phosphorylates argonaute 2 (AGO2), a critical factor in the biogenesis of microRNAs, and that this process is enhanced by hypoxia. This modification of AGO2 impairs microRNA processing, but promotes cell survival and invasiveness. Breast cancer patients with higher phospho-AGO2 content show a poorer outcome. MicroRNAs (miRNAs) are generated by two-step processing to yield small RNAs that negatively regulate target gene expression at the post-transcriptional level 1 . Deregulation of miRNAs has been linked to diverse pathological processes, including cancer 2 , 3 . Recent studies have also implicated miRNAs in the regulation of cellular response to a spectrum of stresses 4 , such as hypoxia, which is frequently encountered in the poorly angiogenic core of a solid tumour 5 . However, the upstream regulators of miRNA biogenesis machineries remain obscure, raising the question of how tumour cells efficiently coordinate and impose specificity on miRNA expression and function in response to stresses. Here we show that epidermal growth factor receptor (EGFR), which is the product of a well-characterized oncogene in human cancers, suppresses the maturation of specific tumour-suppressor-like miRNAs in response to hypoxic stress through phosphorylation of argonaute 2 (AGO2) at Tyr 393. The association between EGFR and AGO2 is enhanced by hypoxia, leading to elevated AGO2-Y393 phosphorylation, which in turn reduces the binding of Dicer to AGO2 and inhibits miRNA processing from precursor miRNAs to mature miRNAs. We also identify a long-loop structure in precursor miRNAs as a critical regulatory element in phospho-Y393-AGO2-mediated miRNA maturation. Furthermore, AGO2-Y393 phosphorylation mediates EGFR-enhanced cell survival and invasiveness under hypoxia, and correlates with poorer overall survival in breast cancer patients. Our study reveals a previously unrecognized function of EGFR in miRNA maturation and demonstrates how EGFR is likely to function as a regulator of AGO2 through novel post-translational modification. These findings suggest that modulation of miRNA biogenesis is important for stress response in tumour cells and has potential clinical implications.

[This corrects the article DOI: 10.1371/journal.pone.0298338.].

The significance of DNA hydroxymethylation in replicative senescence of mesenchymal stem cells (MSCs) and aging-related osteoporosis remains unknown. Here, we reveal 5hmC levels positively regulate MSC self-renewal and osteoblast differentiation. Mechanistically, PARP1 recruits TET1 to hydrolyze methylated nucleotides on DNMT1 exons, aiding CTCF in preventing DNMT1 alternative splicing in early MSCs. Additionally, ATM phosphorylates TRIM37 at Th203, promoting its nuclear entry and the monoubiquitination of PARP1, stabilizing the protein. CTCF or TRIM37 knockdown induces replicative senescence of MSCs with loss of full-length DNMT1. Co-treatment with resveratrol (ATM activator) and vitamin C (TET1 activator) rejuvenates late MSCs via the TRIM37/PARP1/DNMT1 pathway and alleviates osteoporosis in aged mice. Gene knockout experiments further reveal the participation of TRIM37 and PARP1 in MSC aging, contributing significantly to bone maintenance and repair in vivo. This study emphasizes the role of DNA hydroxymethylation in stemness, suggesting therapeutic strategies, especially for osteoporosis. TRIM37–PARP1–TET1 signalling preserves stem cell function and prevents osteoporosis by regulating DNMT1 splicing through 5hmC maintenance, revealing a mechanism linking epigenetic control to stem cell function and bone health.

Esophageal squamous cell carcinoma (ESCC) accounts for about 90% of esophageal cancer diagnosed in Asian countries, with its incidence on the rise. Cancer stem cell (CSC; also known as tumor-initiating cells, TIC) is inherently resistant to cytotoxic chemotherapy and radiation and associates with poor prognosis and therapy failure. Targeting therapy against cancer stem cell has emerged as a potential therapeutic approach to develop effective regimens. However, the suitable CSC marker of ESCC for identification and targeting is still limited. In this study, we screened the novel CSC membrane protein markers using two distinct stemness characteristics of cancer cell lines by a comparative approach. After the validation of RT-PCR, qPCR and western blot analyses, intercellular adhesion molecule 1 (ICAM1) was identified as a potential CSC marker of ESCC. ICAM1 promotes cancer cell migration, invasion as well as increasing mesenchymal marker expression and attenuating epithelial marker expression. In addition, ICAM1 contributes to CSC properties, including sphere formation, drug resistance, and tumorigenesis in mouse xenotransplantation model. Based on the analysis of ICAM1-regulated proteins, we speculated that ICAM1 regulates CSC properties partly through an ICAM1-PTTG1IP-p53-DNMT1 pathway. Moreover, we observed that ICAM1 and CD44 could have a compensation effect on maintaining the stemness characteristics of ESCC, suggesting that the combination of multi-targeting therapies should be under serious consideration to acquire a more potent therapeutic effect on CSC of ESCC.

The black soldier fly (BSF), Hermetia illucen s, has the potential to serve as a valuable resource for waste bioconversion due to the ability of the larvae to thrive in a microbial-rich environment. Being an ecological decomposer, the survival of BSF larvae (BSFL) relies on developing an efficient defense system. Cathepsin L (CTSL) is a cysteine protease that plays roles in physiological and pathological processes. In this study, the full-length of CTSL was obtained from BSF. The 1,020-bp open reading frame encoded a preprotein of 339 amino acids with a predicted molecular weight of 32 kDa. The pro-domain contained the conserved ERFNIN, GNYD, and GCNGG motifs, which are all characteristic of CTSL. Homology revealed that the deduced amino acid sequence of BSF CTSL shared 74.22–72.99% identity with Diptera flies. Immunohistochemical (IHC) analysis showed the CTSL was predominantly localized in the gut, especially in the midgut. The mRNA expression of CTSL in different larval stages was analyzed by quantitative real-time PCR (RT-qPCR), which revealed that CTSL was expressed in the second to sixth instar, with the highest expression in the fifth instar. Following an immune challenge in vivo using Escherichia coli ( E . coli ), CTSL mRNA was significantly up-regulated at 6 h post-stimulation. The Z-Phe-Arg-AMC was gradually cleaved by the BSFL extract after 3 h post-stimulation. These results shed light on the potential role of CTSL in the defense mechanism that helps BSFL to survive against pathogens in a microbial-rich environment.

Bladder cancer poses a significant challenge to chemotherapy due to its resistance to cisplatin, especially at advanced stages. Understanding the mechanisms behind cisplatin resistance is crucial for improving cancer therapy. The enzyme glutathione S‐transferase omega class 1 (GSTO1) is known to be involved in cisplatin resistance in colon cancer. This study focused on its role in cisplatin resistance in bladder cancer. Our analysis of protein expression in bladder cancer cells stimulated by secretions from tumor‐associated macrophages (TAMs) showed a significant increase in GSTO1. This prompted further investigation into the role of GSTO1 in bladder cancer. We found a strong correlation between GSTO1 expression and cisplatin resistance. Mechanistically, GSTO1 triggered the release of large extracellular vesicles (EVs) that promoted cisplatin efflux, thereby reducing cisplatin–DNA adduct formation and enhancing cisplatin resistance. Inhibition of EV release effectively counteracted the cisplatin resistance associated with GSTO1. In conclusion, GSTO1‐mediated EV release may contribute to cisplatin resistance caused by TAMs in bladder cancer. Strategies to target GSTO1 could potentially improve the efficacy of cisplatin in treating bladder cancer. In bladder cancer, the expression of glutathione S‐transferase omega 1 (GSTO1) can be induced by tumor‐associated macrophage‐secreted tumor necrosis factor‐alpha. The overexpression of GSTO1 causes cisplatin resistance through cisplatin efflux mediated by the generation of large extracellular vesicles. Targeting GSTO1 may represent a promising therapeutic strategy to enhance the efficacy of cisplatin treatments.

Docetaxel (DTX) combined with cisplatin and 5-fluorouracil has been used as induction chemotherapy for head and neck squamous cell carcinoma (HNSCC). However, the development of acquired resistance remains a major obstacle to treatment response. Tumor-associated macrophages are associated with chemotherapeutic resistance. In the present study, increased infiltration of macrophages into the tumor microenvironment (TME) was significantly associated with shorter overall survival and increased resistance to chemotherapeutic drugs, particularly DTX, in patients with HNSCC. Macrophage coculture induced expression of intercellular adhesion molecule 1 (ICAM1), which promotes stemness and the formation of polyploid giant cancer cells, thereby reducing the efficacy of DTX. Both genetic silencing and pharmacological inhibition of ICAM1 sensitized HNSCC to DTX. Macrophage secretion of IL-1β was found to induce tumor expression of ICAM1. IL-1β neutralization and IL-1 receptor blockade reversed DTX resistance induced by macrophage coculture. IL-1β activated superoxide dismutase 2 and inhibited catalase, thereby modulating intracellular levels of ROS and inducing ICAM1 expression. Arsenic trioxide (ATO) reduced macrophage infiltration into the TME and impaired IL-1β secretion by macrophages. The combinatorial use of ATO enhanced the in vivo efficacy of DTX in a mouse model, which may provide a revolutionary approach to overcoming acquired therapeutic resistance in HNSCC.

Background The treatment of recurrent or metastatic head and neck squamous-cell carcinoma (R/M HNSCC) remains challenging. Preclinical studies revealed that B cell depletion could modulate the microenvironment and overcome chemoresistance. We conducted a phase I study to evaluate the feasibility and safety of B cell depletion using the anti-CD20 antibody rituximab to treat HNSCC. Methods Ten patients were enrolled in two protocols. The first four patients treated using protocol 1 received rituximab 1000 mg on days −14 and −7, followed by gemcitabine/cisplatin every 3 weeks, and rituximab was administered every 6 months thereafter. Because of disease hyperprogression, protocol 1 was amended to protocol 2, which consisted of the concomitant administration of rituximab 375 mg/m 2 and gemcitabine/cisplatin every 3 weeks. Another six patients were enrolled and treated using protocol 2. Results Three patients treated using protocol 1 exhibited rapid disease progression, and the remaining patient could not undergo evaluation after rituximab treatment. Conversely, no unpredicted harm was observed in the six patients treated using protocol 2. Among these patients, one achieved complete response, and two had partial responses. The disease-free durations in these patients were 7.0, 6.2, and 7.1 months, respectively. Immune cell analysis revealed a higher ratio of cytotoxic T cells to regulatory T cells in responders than in non-responders. Conclusions B cell depletion using rituximab alone in patients with HNSCC can cause hyperprogressive disease. Contrarily, the co-administration of rituximab and cisplatin/gemcitabine was feasible and safe. Trial registration ClinicalTrials.gov Identifier: NCT04361409 , 24 April 2020, retrospectively registered