SIRT6 acts as a tumour suppressor in multiple cancers by regulating glucose and lipid metabolism, but its role in intrahepatic cholangiocarcinoma (ICC) remains unclear.
We investigated the role and molecular mechanisms of SIRT6 in ICC development and progression.
Spatial transcriptome and single-cell sequencing data from public ICC cohorts and clinical specimens were used to establish the clinical relevance of SIRT6 overexpression. B/R cell-established allografts and AKT/YAP-induced primary ICC mouse models were used to investigate the oncogenic role of SIRT6. The function of SIRT6 in metabolic regulation was assessed using seahorse analysis, metabolomics and isotope tracing. The transcriptional targets of SIRT6 were screened by RNA sequencing and confirmed by dual-luciferase assay and chromatin immunoprecipitation, and the molecular interactions and deacetylation activity of SIRT6 were analysed via co-immunoprecipitation.
SIRT6 was highly expressed in both human and mouse ICC tissues and cell lines. SIRT6 knockdown significantly inhibited ICC cell growth in vitro and ICC development in mouse models. Hydrodynamic co-injection of SIRT6 and AKT resulted in ICC formation in mice. SIRT6 promoted glutamine synthesis by enhancing GLUL transcription and stabilising GLUL protein degradation. SIRT6 silencing decreased glutamine levels, subsequently reducing the levels of nucleotides and amino acids in ICC cells. Thus, SIRT6 or GLUL inhibitors can suppress ICC progression and significantly enhance the sensitivity to chemotherapy.
Our findings establish SIRT6 as an oncogenic driver in ICC by orchestrating glutamine metabolic reprogramming and highlight the SIRT6-GLUL axis as a potential therapeutic target for ICC.
Chronic hepatitis B virus (HBV) infection disproportionately affects people living with HIV, who are often excluded from functional cure studies.
This study investigates CD8+ T cell profiles in HBV mono-infection versus HBV/HIV co-infection, examining the impact of long-term therapy on virus-specific responses to inform therapeutic strategies for immune restoration.
We analysed CD8+ T cell responses in 61 participants (HBV n=20, HBV/HIV n=20, HIV n=21), on suppressive antiviral therapy, assessing transcriptomic and proteomic profiles, focusing on exhaustion markers alongside virus-specific functional capabilities.
Transcriptomic analysis revealed distinct signatures in co-infection, with upregulation of TCR signalling genes, inhibitory pathways and progenitor-exhausted markers (XCL2, TCF7, PDCD1, IL7R). This profile scored highly for a precursor exhausted (Tpex) CD8+ T cell signature, reflecting stemness that maintains plasticity despite chronic antigen exposure. Proteomic analysis confirmed higher frequencies of Tpex (TCF-1+CD127+PD-1+) CD8+ T cells in co-infection, while HBV mono-infection showed predominance of terminally exhausted ToxhighTCF-1-CD127- cells. Tpex enrichment extended to HBV-specific populations corresponding with more robust, polyfunctional HBV-specific responses in co-infection against surface and core antigens. HBV-specific CD8 T cells maintained enhanced proliferative capacity and checkpoint responsiveness to anti-PDL1 blockade compared with HBV mono-infection. While co-infection was characterised by lower HBsAg levels and longer treatment duration, these factors alone did not account for the distinct immunological profiles.
People with well-controlled HBV/HIV co-infection maintain robust CD8+ T cell responses with preserved stem-like properties supporting antiviral function. These results challenge assumptions about additive immune dysfunction in dual chronic infections and highlight the need for tailored immune-modulatory therapies.
Most patients with biliary tract cancer (BTC) do not derive durable clinical benefit (DCB) from immune checkpoint inhibitors (ICIs), underscoring the urgent need for predictive biomarkers. While urinary proteomics represents a non-invasive approach for biomarker discovery and mechanism exploration, its utility in ICI-treated patients with cancer remains unexplored.
We aimed to establish urinary proteomics as a predictive tool for ICI responsiveness and to elucidate its relationship with tumour dynamics and tumour microenvironment (TME) remodelling in BTC.
We performed a staged mass spectrometry (MS)-based discovery-validation proteomics workflow in 211 urine samples from 97 treatment-naïve patients with BTC undergoing ICI-based therapy. A machine learning model was developed based on baseline proteomic features for ICI response prediction. Single-cell transcriptomics of 11 pretreatment tumour biopsies and spatial transcriptomics were integrated to explore the link between urinary proteomics and TME.
Patients achieving DCB exhibited enrichment of immune activation and systemic inflammatory pathways, whereas non-durable benefit was correlated with protumourigenic processes. Longitudinal urinary proteomic dynamics could mirror TME remodelling and tumour evolution. A machine learning-derived 4-urinary protein panel (protein tyrosine phosphatase non-receptor 13 (PTPN13), SUB1, MICAL-L1, VARS1) robustly predicted DCB and early responses. Subsequent external validation in an independent cohort (n=24) using parallel reaction monitoring-MS further confirms its generalisability. PTPN13+ malignant cells were identified as key regulators of proapoptotic TME states, contributing to sustained ICI responsiveness.
This study pioneers the application of urinary proteomics in immuno-oncology, providing a non-invasive approach to predict and monitor ICI responsiveness, while offering mechanistic insights into TME dynamics in BTC.