Xiao-Mei Yang

Cellular adaptive volume regulation is essential for maintaining metabolic homeostasis and supporting survival, yet its role in desmoplastic pancreatic ductal adenocarcinoma (PDAC) remains incompletely understood. Through comprehensive bioinformatic and functional studies, we identified LRRC8A, the core subunit of volume-regulated anion channels (VRAC), as a central regulator linking volume homeostasis to PDAC progression. Beyond its established role in osmotic stress responses, genetic silencing or pharmacological inhibition of LRRC8A revealed its critical function in proliferation-associated volumetric expansion during S-phase. Functional validation through in vitro proliferation assays, in vivo xenograft models, and patient-derived pancreatic cancer organoids (PDO) demonstrated that LRRC8A critically drives PDAC progression. Mechanistically, LRRC8A coordinates plasma membrane dynamics, cortical cytoskeletal organization, membrane-delimited oncogenic signaling (KRAS/EGFR), and nucleolar ribosome biogenesis to support volumetric expansion during S phase. Co-immunoprecipitation coupled with mass spectrometry identified that LRRC8A forms complexes with Caveolin 1 (CAV1). Disruption of LRRC8A leads to decreased CAV1 protein levels, impaired activation of KRAS and EGFR oncogenic signaling, and suppressed ribosome biogenesis and global protein synthesis. Reciprocally, CAV1 knockdown or cholesterol depletion using lovastatin destabilized LRRC8A in plasma membrane, resulting in reduced cortical F-actin organization, oncogenic signaling and biosynthetic activity, indicating that LRRC8A and CAV1 are mutually stabilized and depend on cholesterol-rich membrane microdomains for proper integration and function. Furthermore, disruption of LRRC8A-CAV1 axis through LRRC8A inhibition or cholesterol depletion potently suppressed PDO growth in vitro. Collectively, our work establishes the LRRC8A-CAV1 complex as a key coordinator of biosynthetic expansion and a promising therapeutic target in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a poor prognosis, in which the role of lipophagy, a selective autophagic process degrading lipid droplets (LDs), remains poorly characterized. This study investigated lipophagy and its key regulator, OSBPL10, in PDAC progression. Through immunofluorescence analysis of patient samples, transgenic mouse tissues, and cell lines, we find that lipophagy is elevated in PDAC and correlates with poor prognosis. Single-cell transcriptomic analysis identified OSBPL10 as a critical lipophagy regulator and an independent clinicopathological indicator. Functional assays, including orthotopic and subcutaneous xenografts, demonstrated that OSBPL10 promotes tumor growth. Mechanistically, OSBPL10 functionally cooperates with VAPA/VAPB to facilitate rapid lysosomal repair via ATG2A, thereby promoting lipophagy and lipid mobilization. Inhibition of lysosomal function abrogated the pro-lipophagic and pro-tumorigenic effects of OSBPL10. Collectively, our findings demonstrate that upregulated OSBPL10 drives PDAC progression by enhancing lipophagy through ATG2A-mediated rapid lysosomal repair, highlighting OSBPL10 as a potential therapeutic target in PDAC.

Perineural invasion (PNI) is a common pathological characteristic of pancreatic ductal adenocarcinoma (PDAC), closely linked to postoperative recurrence, metastasis, and unfavorable prognosis. Nevertheless, the precise mechanisms that govern PNI in PDAC remain poorly elucidated. Here, group‐specific component protein (GC) is identified as one of the most significantly upregulated genes related to PNI, primarily derived from malignant ductal cells compared to other cell types. GC knockdown attenuates PDAC cell invasiveness toward nerves, and this effect operates independently of vitamin D transport. Moreover, GC protein activates Schwann cells by inducing a dedifferentiation program, and enhances the mutual chemoattraction between PDAC cells and Schwann cells. Mechanistically, integrin β1 (ITGB1) serves as the functional receptor for GC protein in both PDAC and Schwann cells. Targeting the ITGB1‐FAK signaling cascade proves effective in reducing PNI and Schwann cell activation. In KPC (Pdx‐Cre; LSL‐Kras ^G12D+ ; LSL‐Trp53 ^R172H/+ ) mice and orthotopic xenografts model, GC silencing and ITGB1 blockade both efficiently reduce cancer‐nerve interactions and mitigate PDAC progression. Clinically, GC protein, ITGB1, and phosphorylated‐FAK are positively associated with the severity of PNI in PDAC cases. Collectively, these data demonstrate that GC protein engages integrin receptor signaling to display distinct functions in cancer cells and Schwann cells, thus enabling PNI.

Background: Immune evasion is a crucial event in the progression of pancreatic ductal adenocarcinoma (PDAC). The identification of new immunotherapeutic targets may provide a promising platform for advancing PDAC treatment. This study aims to investigate the role of beta-1,4-galactosyltransferase-5 (B4GALT5) in immune evasion by pancreatic cancer cells and evaluate its potential as an immunotherapeutic target. Methods: We conducted a comprehensive analysis using RNA sequencing data and tissue microarrays from patients with PDAC to investigate the association between B4GALT5 expression and patient prognosis. Using animal models, we further explored the impact of B4GALT5 on the quantity and activity of tumor-infiltrating CD8⁺ T cells. RNA sequencing and co-immunoprecipitation were used to explore the mechanism by which B4GALT5 regulates major histocompatibility complex (MHC-I) levels. Results: Our study demonstrates that high expression of B4GALT5 in tumor cells is significantly associated with poor prognosis in patients with PDAC and reduced cytotoxic activity of tumor-infiltrating CD8⁺ T cells. Specifically, B4GALT5 suppresses MHC-I expression in tumor cells through the endoplasmic reticulum-associated degradation pathway, enabling them to evade immune surveillance by CD8⁺ T cells. Conclusions: B4GALT5 impairs CD8⁺ T-cell recognition of tumor cells by regulating MHC-I levels, thereby promoting immune evasion. This makes B4GALT5 a highly promising immunotherapeutic target for improving the poor prognosis of patients with PDAC.

Background: Vitamin K‐dependent γ‐glutamic acid carboxylation (Gla) proteins are calcium‐binding and membrane‐associated, participating in coagulation, bone turnover, and cancer biology. The molecular function of transmembrane proline‐rich Gla proteins (PRRGs) remains unexplored.Methods: Analysis of pancreatic ductal adenocarcinoma (PDAC) datasets, including transcription profiles, clinical data, and tissue microarrays, was conducted to evaluate PRRG1 expression and its clinical relevance. PDAC cell lines with overexpressed, knockdown, and mutated PRRG1 were developed to study biological functions and pathways using RNA‐seq, co‐immunoprecipitation with mass spectrometry, Western blotting, and immunofluorescence. In vivo xenograft and orthotopic models assessed PRRG1's impact on PDAC progression, with and without warfarin treatment.Results: PRRG1 was significantly upregulated in PDAC compared to normal pancreas, correlating with poorer patient survival. PRRG1 knockdown reduced PDAC cell proliferation, anchorage‐independent growth in vitro, and tumor growth in vivo. PRRG1 localized at the plasma membrane, interacted with the HECT E3 ligase NEDD4 via the C‐terminal PPXY motif, and promoted NEDD4 self‐ubiquitination, reducing its protein levels. PRRG1 knockdown elevated NEDD4, destabilizing the oncoprotein KRAS and receptor EGFR, and attenuating downstream signaling and macropinocytosis under nutrient deprivation. The vitamin K‐dependent Gla modification of PRRG1 was crucial for its membrane localization and pro‐tumorigenic effects, and was inhibited by low‐dose warfarin, a clinical vitamin K antagonist.Conclusions: This study identifies PRRG1 as a key regulator of pro‐tumorigenic signaling in PDAC, suggesting the potential of repurposing the anticoagulant warfarin as a therapeutic strategy.Key points: PRRG1 is identified as the transmembrane Gla protein mediating PDAC malignancy. PRRG1 recruits and induces self‐ubiquitination of membrane‐anchoring E3 ligase NEDD4. PRRG1 exerts a protective role toward KRAS and EGFR by inhibiting NEDD4. The anticoagulant warfarin can be utilized to inhibit PRRG1 and PDAC advancement.

Rationale: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a global prevalence and poor prognosis, largely due to immune escape mechanisms. However, the potential reasons for the decreased infiltration of cytotoxic T lymphocytes (CTLs) in PDAC remain inadequately understood. In this study, we aimed to elucidate the molecular mechanisms contributing to the low-CTLs infiltration in patients with PDAC.

Background: The interaction between the metastatic microenvironment and tumor cells plays an important role in metastatic tumor formation. Platelets play pivotal roles in hematogenous cancer metastasis through tumor cell‐platelet interaction in blood vessels. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy distinguished by its notable tendency to metastasize to the liver. However, the role of platelet in the liver metastatic niche of PDAC remains elusive. This study aimed to elucidate the role of platelets and their interactions with tumor cells in the liver metastatic niche of PDAC. Methods: An mCherry niche‐labeling system was established to identify cells in the liver metastatic niche of PDAC. Platelet depletion in a liver metastasis mouse model was used to observe the function of platelets in PDAC liver metastasis. Gain‐of‐function and loss‐of‐function of erythropoietin‐producing hepatocellular receptor B1 ( Ephb1 ), tumor cell‐platelet adhesion, recombinant protein, and tryptophan hydroxylase 1 ( Tph1 )‐knockout mice were used to study the crosstalk between platelets and tumor cells in the liver metastatic niche. Results: The mCherry metastatic niche‐labeling system revealed the presence of activated platelets in the liver metastatic niche of PDAC patients. Platelet depletion decreased liver metastatic tumor growth in mice. Mechanistically, tumor cell‐expressed EPHB1 and platelet‐expressed Ephrin B1 (EFNB1) mediated contact‐dependent activation of platelets via reverse signaling‐mediated AKT signaling activation, and in turn, activated platelet‐released 5‐HT, further enhancing tumor growth. Conclusion: We revealed the crosstalk between platelets and tumor cells in the liver metastatic niche of PDAC. Reciprocal tumor‐platelet interaction mediated by the EPHB1‐EFNB1 reverse signaling promoted metastatic PDAC outgrowth via 5‐HT in the liver. Interfering the tumor‐platelet interaction by targeting the EPHB1‐EFNB1 axis may represent a promising therapeutic intervention for PDAC liver metastasis.

Purpose Transglutaminases (TGs) are multifunctional enzymes exhibiting transglutaminase crosslinking, as well as atypical GTPase/ATPase and kinase activities. Here, we used an integrated comprehensive analysis to assess the genomic, transcriptomic and immunological landscapes of TGs across cancers. Methods Gene expression and immune cell infiltration patterns across cancers were obtained from The Cancer Genome Atlas (TCGA) database and Gene Set Enrichment Analysis (GSEA) datasets. Western blotting, immunofluorescence staining, enzyme-linked immunosorbent assays, and orthotopic xenograft models were used to validate our database-derived results. Results We found that the overall expression of TGs (designated as the TG score) is significantly upregulated in multiple cancers and related to a worse patient survival. The expression of TG family members can be regulated through multiple mechanisms at the genetic, epigenetic and transcriptional levels. The expression of transcription factors crucial for epithelial-to-mesenchymal transition (EMT) is commonly correlated with the TG score in many cancer types. Importantly, TGM2 expression displays a close connection with chemoresistance to a wide range of chemotherapeutic drugs. We found that TGM2 expression, F13A1 expression and the overall TG score were positively correlated with the infiltration of immune cells in all cancer types tested. Functional and clinical verification revealed that a higher TGM2 expression is linked with a worse patient survival, an increased IC₅₀ value of gemcitabine, and a higher abundance of tumor-infiltrating macrophages in pancreatic cancer. Mechanistically, we found that increased C–C motif chemokine ligand 2 (CCL2) release mediated by TGM2 contributes to macrophage infiltration into the tumor microenvironment. Conclusions Our results reveal the relevance and molecular networks of TG genes in human cancers and highlight the importance of TGM2 in pancreatic cancer, which may provide promising directions for immunotherapy and for addressing chemoresistance.