A ligamentum teres hepatis and falciform ligament 'belt and braces' approach in laparoscopic pancreaticoduodenectomy using a modified Blumgart anastomosis to minimize severe pancreatic fistula and post-operative complications.

BACKGROUND: To determine whether ligamentum teres hepatis and falciform ligament, wrapped around the gastroduodenal artery (GDA) and reinforced the posterior wall in pancreatojejunostomy (PJ), protects the GDA stump and other skeletal blood vessels from erosive hemorrhage and reduces the incidence of clinically relevant post-operative pancreatic fistula (CR-POPF) and post-operative complications after laparoscopic pancreaticoduodenectomy (LPD). METHODS: We reviewed patients undergone LPD between January 2019 and June 2023. Patients were divided into two groups according to whether the ligamentous flap had been used to wrap the GDA stump (Group A) or to reinforce the posterior wall in PJ, together with the GDA wrapping procedure (Group B). Peri-operative data were reviewed to determine the effectiveness of this approach in preventing CR-POPF, post-pancreatectomy hemorrhage (PPH), and other complications. RESULTS: We enrolled 272 patients (Group A, 154 patients; Group B, 118 patients). Group B patients had significantly fewer ≥ Grade II Clavien-Dindo classification morbidities and CR-POPFs (P < 0.05), and lower length of hospital stay (LOS) and abdominal drainage tube insertion times. Risk factor analysis indicated that main pancreatic duct dilation, the PJ reinforcement procedure, and soft pancreatic tissue were associated with ≥Grade II Clavien-Dindo morbidities and CR-POPF complications. CONCLUSIONS: The ligamentous flap application in LPD provided shelter to GDA stump and other skeletal blood vessels under PJ from erosive digestive juices, reinforced the posterior wall in PJ, reduced the incidence of CR-POPF and ≥Grade II Clavien-Dindo classification morbidities. This simple procedure is effective for improving surgical safety of LPD.

IL15RA-STAT3-GPX4/ACSL3 signaling leads to ferroptosis resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant disease with a poor prognosis, and the lack of effective treatment methods accounts for its high mortality. Pancreatic stellate cells (PSCs) in the tumor microenvironment play an important role in the development of PDAC. Previous studies have reported that patients with PDAC are more vulnerable to ferroptosis inducers. To investigate the relationship between PSCs and pancreatic cancer cells, a coculture system is used to further reveal the influence of PSCs on ferroptosis resistance in PDAC using many in vitro and in vivo experiments. Our results show that PSCs promote ferroptosis resistance in pancreatic cancer cells. We further demonstrate that IL15 secretion by PSCs activates the IL15RA-STAT3-GPX4/ACSL3 axis. The simultaneous upregulation of GPX4 and ACSL3 prevents lipid peroxidation and ultimately protects pancreatic cancer cells from ferroptosis both in vitro and in vivo. This study demonstrates that PSCs protect pancreatic cancer cells in a paracrine manner and may indicate a novel strategy for the treatment of PDAC.

The complement C3a/C3aR pathway is associated with treatment resistance to gemcitabine-based neoadjuvant therapy in pancreatic cancer.

Gemcitabine is a standard first-line drug for pancreatic cancer chemotherapy. Nevertheless, gemcitabine resistance is common and significantly limits its therapeutic efficacy, impeding advancements in pancreatic cancer treatment. In this study, through a comprehensive analysis of gemcitabine-resistant cell lines and patient samples, 39 gemcitabine resistance-associated risk genes were identified, and two distinct gemcitabine response-related phenotypes were delineated. Through a combination of bioinformatics analysis and in vivo and in vitro experiments, we identified the C3a/C3aR signaling pathway as a pivotal player in the development of gemcitabine resistance in pancreatic cancer. We found that activation of the C3a/C3aR signaling pathway promoted the proliferation, migration and gemcitabine resistance of pancreatic cancer cells, while the C3aR antagonist SB290157 effectively counteracted these effects by impeding the activation of the C3a/C3aR pathway. Our study reveals the fundamental role of complement C3a in the progression of pancreatic cancer, suggesting that complement C3a may serve as a promising biomarker in pancreatic cancer.

Phase 1b study of first-line fuzuloparib combined with modified FOLFIRINOX followed by fuzuloparib maintenance monotherapy in pancreatic adenocarcinoma.

BACKGROUND: Chemotherapy remains the standard first-line treatment for pancreatic adenocarcinoma, but with limited efficacy. We aimed to explore the feasibility of adding the PARP inhibitor fuzuloparib to mFOLFIRINOX in the locally advanced/metastatic (LA/M) setting. METHODS: This was the dose-escalation and -expansion, phase 1b portion of a phase 1b/2 study. Patients were given oral fuzuloparib at escalating doses starting at 30 mg twice daily (BID) plus intravenous mFOLFIRINOX q2w for 8-12 cycles, followed by maintenance fuzuloparib at 150 mg BID. Cohorts at the maximal tolerated dose (MTD) and lower dose of fuzuloparib were expanded. Primary endpoints were dose-limiting toxicity (DLT), MTD, and recommended phase 2 dose (RP2D). RESULTS: As of data cutoff on Jan 15, 2023, 39 patients were recruited. 12 patients were enrolled during dose escalation (30 mg [n = 4]; 60 mg [n = 6]; 100 mg [n = 2]). DLT occurred in 1 patient in 60 mg cohort and 1 patient in 100 mg cohort. 60 mg BID was determined to be the MTD, and then 60 and 30 mg cohorts were expanded to 22 and 15 patients, respectively. The most common grade ≥ 3 treatment-related adverse events were hematologic toxicities. Efficacy in 60 mg cohort seemed to be most favorable, with an objective response rate of 50.0% (95% CI, 26.0-74.0) and disease control rate of 94.4% (95% CI, 72.7-99.9). CONCLUSIONS: First-line fuzuloparib plus mFOLFIRINOX followed by maintenance fuzuloparib was generally safe and showed encouraging anti-tumor activity in patients with LA/M pancreatic adenocarcinoma. The RP2D of fuzuloparib combination was 60 mg BID. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04228601.

CircRREB1 Mediates Metabolic Reprogramming and Stemness Maintenance to Facilitate Pancreatic Ductal Adenocarcinoma Progression.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal tumor with limited treatment options and poor patient survival. Circular RNAs (circRNAs) play crucial regulatory roles in the occurrence and development of various cancers, including PDAC. Here, using circRNA sequencing of diverse PDAC samples, we identified circRREB1 as an oncogenic circRNA that is significantly upregulated in PDAC and is correlated with an unfavorable patient prognosis. Functionally, loss of circRREB1 markedly inhibited glycolysis and stemness, while elevated circRREB1 elicited the opposite effects. Mechanistically, circRREB1 interacted with PGK1, disrupting the association between PTEN and PGK1 and increasing PGK1 phosphorylation to activate glycolytic flux. Moreover, circRREB1 promoted WNT7B transcription by directly interacting with YBX1 and facilitating its nuclear translocation, consequently activating the Wnt/ß-catenin signaling pathway to maintain PDAC stemness. Overall, these results highlight circRREB1 as a key regulator of metabolic and stemness properties of PDAC.

Single-cell sequencing reveals the heterogeneity of pancreatic neuroendocrine tumors under genomic instability and histological grading.

Histological grading is the key factors affecting the prognosis and instructive in guiding treatment and assessing recurrence in non-functional pancreatic neuroendocrine tumor (NF-Pan-NET). Approximately one-third of patients without copy number variation (CNV) alteration and the prognosis of these patients are better than that of patients with CNV alteration. However, the difference between CNV and histological grading is unclear. Here, we analyzed the heterogeneity of tumor cells according to two classification criteria, genomic instability (including CNV alteration and tumor mutation burden) and histological grading. We revealed that the activated core pathways of tumor cells were significantly different under different histological grading's and genomic instability patterns. We also found that tip cells, lymphatic endothelial cells, macrophages, CD1A + dendritic cell, Treg, MAIT, ILC, and CAFs might participate in the process of hepatic metastases, which will facilitate the understanding of the patterns to decode the malignant potential and of NF-Pan-NET.

Unraveling the mysteries of MGMT: Implications for neuroendocrine tumors.

Neuroendocrine tumors (NETs) are a diverse group of tumors that arise from neuroendocrine cells and are commonly found in various organs. A considerable proportion of NET patients were diagnosed at an advanced or metastatic stage. Alkylating agents are the primary treatment for NET, and O6-methylguanine methyltransferase (MGMT) remains the first-line of defense against DNA damage caused by these agents. Clinical trials have indicated that MGMT promoter methylation or its low/lacked expression can predict a favorable outcome with Temozolomide in NETs. Its status could help select NET patients who can benefit from alkylating agents. Therefore, MGMT status serves as a biomarker to guide decisions on the efficacy of Temozolomide as a personalized treatment option. Additionally, delving into the regulatory mechanisms of MGMT status can lead to the development of MGMT-targeted therapies, benefiting individuals with high levels of MGMT expression. This review aims to explore the polymorphism of MGMT regulation and summarize its clinical implications in NETs, which would help establish the role of MGMT as a biomarker and its potential as a therapeutic target in NETs. Additionally, we explore the benefits of combining Temozolomide and immunotherapy in MGMT hypermethylated subgroups. Future studies can focus on optimizing Temozolomide administration to induce specific immunomodulatory changes.

G3BP2 promotes tumor progression and gemcitabine resistance in PDAC via regulating PDIA3-DKC1-hENT in a stress granules-dependent manner.

Pancreatic ductal adenocarcinoma (PDAC) is distinguished by its aggressive malignancy, limited treatment avenues and a tendency towards chemotherapy resistance, underscoring the critical need for advanced research to uncover new therapeutic approaches. Stress granules (SGs) that is implicated in cellular self-protection mechanism, along with its associated family molecules have shown pro-cancer effects and are closely related to tumor chemotherapy resistance. In this study we investigated the relationship between Ras GTPase-activating protein-binding proteins 2 (G3BP2), a core component of SGs, and the malignancy of PDAC as well as its resistance to the chemotherapy drug gemcitabine. Analyzing TCGA dataset revealed that the expression of G3BP1 and G3BP2 was significantly upregulated in PDAC compared with adjacent normal pancreatic tissues, and the high expression of G3BP2 rather than G3BP1 was significantly associated with poorer overall survival (OS) in PDAC patients. We demonstrated that knockdown of G3BP2 inhibited the proliferation and invasion of PANC-1 and CFPAC-1 cells in vitro and in vivo. By analyzing the differentially expressed genes in G3BP2 knockdown and overexpressed PANC-1 cells, we identified DKC1 that was associated with RNA stability and regulation as the target of G3BP2. We demonstrated that G3BP2 bound to PDIA3 mRNA and recruited them into SGs, increasing the stability of PDIA3 mRNA and attenuating its translation efficiency, thereby promoting DKC1 expression. Furthermore, DKC1 could bind to hENT mRNA and inhibited its expression, which enhanced gemcitabine resistance of PDAC. Therefore, we propose a novel mechanism wherein G3BP2 facilitates PDAC's resistance to chemotherapy by modulating PDIA3-DKC1-hENT in a SGs-dependent way, suggesting G3BP2 SGs a protentional therapeutic target for the treatment in PDAC.

Laparoscopic Duodenum and Spleen-Preserving Subtotal or Total Pancreatectomy: A Parenchyma-Sparing Strategy for Main Duct Intraductal Papillary Mucinous Neoplasms (with Video).

BACKGROUND: For premalignant main duct intraductal papillary mucinous neoplasms (MD-IPMN), laparoscopic duodenum and spleen-preserving subtotal or total pancreatectomy (LDSP-STP/TP) seems to be a viable option for parenchyma-sparing pancreatectomy. PATIENTS AND METHODS: On the basis of the imaging features, family history, genomic alterations, intraoperative ultrasound examination, and frozen section evaluation, we have proposed patient selection strategies for the LDSP-STP/TP technique for the first time. Additionally, a comprehensive step-by-step overview of this technique has been provided. To date, we have performed five LDSP-STP procedures and one LDSP-TP procedure. RESULTS: We successfully performed selective resection of the affected pancreatic parenchyma while preserving the duodenum, common bile duct (CBD), spleen, and splenic artery and vein. The operation time ranged from 295 to 495 min, with blood loss ranging from 100 to 300 mL. Postoperative pathological results revealed low-grade dysplasia in the resected pancreatic samples and margins. The patients resumed eating within 3-5 days after surgery, and all postoperative complications were classified as grade I according to the Clavien-Dindo classification. At the 3-month follow-up, there were no cases of CBD ischemic stenosis, splenic ischemia, or pseudocyst formation observed. For patients who received LDSP-STP, the longitudinal diameter of the remaining pancreatic tail ranged from 2.2 to 4.6 cm, and they demonstrated satisfactory long-term blood glycemic control. CONCLUSIONS: LDSP-STP/TP demonstrates technical feasibility and safety. It allows for the selective resection of the affected pancreatic parenchyma, thereby minimizing the impact of pancreatic functional impairment. However, it is crucial to validate this technique through long-term prospective observations.

NLRP4 renders pancreatic cancer resistant to olaparib through promotion of the DNA damage response and ROS-induced autophagy.

Olaparib has been approved as a therapeutic option for metastatic pancreatic ductal adenocarcinoma patients with BRCA1/2 mutations. However, a significant majority of pancreatic cancer patients have inherent resistance or develop tolerance to olaparib. It is crucial to comprehend the molecular mechanism underlying olaparib resistance to facilitate the development of targeted therapies for pancreatic cancer. In this study, we conducted an analysis of the DepMap database to investigate gene expression variations associated with olaparib sensitivity. Our findings revealed that NLRP4 upregulation contributes to increased resistance to olaparib in pancreatic cancer cells, both in vitro and in vivo. RNA sequencing and Co-IP MS analysis revealed that NLRP4 is involved in the DNA damage response and autophagy pathway. Our findings confirmed that NLRP4 enhances the capacity for DNA repair and induces the production of significant levels of reactive oxygen species (ROS) and autophagy in response to treatment with olaparib. Specifically, NLRP4-generated mitochondrial ROS promote autophagy in pancreatic cancer cells upon exposure to olaparib. However, NLRP4-induced ROS do not affect DNA damage. The inhibition of mitochondrial ROS using MitoQ and autophagy using chloroquine (CQ) may render cells more susceptible to the effects of olaparib. Taken together, our findings highlight the significant roles played by NLRP4 in the processes of autophagy and DNA repair when pancreatic cancer cells are treated with olaparib, thereby suggesting the potential therapeutic utility of olaparib in pancreatic cancer patients with low NLRP4 expression.

Outcomes of patients with initially unresectable pancreatic cancer who underwent conversion surgery after FOLFIRINOX or gemcitabine plus nab-paclitaxel chemotherapy: A multicenter retrospective cohort study (PC-CURE-1).

BACKGROUND: The efficacy and safety of conversion surgery (CS) after FOLFIRINOX or gemcitabine plus nab-paclitaxel (GnP) chemotherapy in patients with initially unresectable pancreatic cancer (PC) remains unclear. METHODS: This multicenter retrospective cohort study enrolled patients, between 2014 and 2018, with initially locally advanced or metastatic PC who were considered candidates for CS following FOLFIRINOX or GnP chemotherapy. They were classified into surgery (207 patients [194 resection and 13 exploratory laparotomy only]) and continued chemotherapy (10 patients, control) groups. The primary endpoint was overall survival (OS) from the day of diagnosis of potentially curative resection on imaging studies, with an expected hazard ratio (HR) of 0.7. RESULTS: OS in the surgery group was longer than that in the control group (HR, 0.47; 95% confidence interval [CI]: 0.24-0.93). The median OS was 34.4 (95% CI: 27.9-43.4) and 19.8 (95% CI: 14.9-31.1) months in the surgery and control groups, respectively. The Clavien-Dindo grade ≥ IIIa postoperative complication and in-hospital mortality rates were 19.6% and 0.5%, respectively. Multivariate analysis revealed that preoperative chemotherapy duration was not associated with OS. CONCLUSIONS: CS, following a favorable response to FOLFIRINOX or GnP chemotherapy, improved initially unresectable PC prognosis (specifically, OS), regardless of the chemotherapy duration.

DNA hypo-methylation and expression of GBP4 induces T cell exhaustion in pancreatic cancer.

Immunotherapy for pancreatic ductal carcinoma (PDAC) remains disappointing due to the repressive tumor microenvironment and T cell exhaustion, in which the roles of interferon-stimulated genes were largely unknown. Here, we focused on a typical interferon-stimulated gene, GBP4, and investigated its potential diagnostic and therapeutic value in pancreatic cancer. Expression analysis on both local samples and public databases indicated that GBP4 was one of the most dominant GBP family members present in the PDAC microenvironment, and the expression level of GBP4 was negatively associated with patient survival. We then identified DNA hypo-methylation in regulatory regions of GBP4 in PDAC, and validated its regulatory role on GBP4 expression via performing targeted methylation using dCas9-SunTag-DNMAT3A-sgRNA-targeted methylation system on selected DNA locus. After that, we investigated the downstream functions of GBP4, and chemotaxis assays indicated that GBP4 overexpression significantly improved the infiltration of CD8+T cells, but also induced upregulation of immune checkpoint genes and T cell exhaustion. Lastly, in vitro T cell killing assays using primary organoids suggested that the PDAC samples with high level of GBP4 expression displayed significantly higher sensitivity to anti-PD-1 treatment. Taken together, our studies revealed the expression patterns and epigenetic regulatory mechanisms of GBP4 in pancreatic cancer and clarified the effects of GBP4 on T cell exhaustion and antitumor immunology.

YBX1 as a therapeutic target to suppress the LRP1-ß-catenin-RRM1 axis and overcome gemcitabine resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is highly malignant and has a poor prognosis, without effective therapeutic targets in common gene mutations. Gemcitabine, a first-line chemotherapeutic for PDAC, confers <10 % 5-year survival rate because of drug resistance. Y-box binding protein 1 (YBX1), associated with multidrug-resistance gene activation, remains unelucidated in PDAC gemcitabine resistance. In vivo and in vitro, we verified YBX1's promotional effects, especially gemcitabine resistance, in pancreatic cancer cells. YBX1-induced LRP1 transcription by binding to the LRP1 promoter region significantly altered the concentration and distribution of ß-catenin in pancreatic cancer cells. Through TCF3, ß-catenin bound to the promoter region of RRM1, a key gene for gemcitabine resistance, that promotes RRM1 expression. Combination therapy with the YBX1 inhibitor SU056 and gemcitabine effectively reduced gemcitabine resistance in in vivo and in vitro experiments. High YBX1 expression promoted pathogenesis and gemcitabine resistance in pancreatic cancer through the YBX1-LRP1-ß-catenin-RRM1 axis. Combining YBX1 inhibitors with gemcitabine may provide a new direction for combination chemotherapy to overcome gemcitabine resistance, which frequently occurs during chemotherapy for pancreatic cancer.

Tibial cortex transverse transport surgery improves wound healing in patients with severe type 2 DFUs by activating a systemic immune response: a cross-sectional study.

BACKGROUND: Tibial cortex transverse transport (TTT) surgery has become an ideal treatment for patients with type 2 severe diabetic foot ulcerations (DFUs) while conventional treatments are ineffective. Based on our clinical practice experience, the protective immune response from TTT surgery may play a role against infections to promote wound healing in patients with DFUs. Therefore, this research aimed to systematically study the specific clinical efficacy and the mechanism of TTT surgery. MATERIALS AND METHODS: Between June 2022 and September 2023, 68 patients with type 2 severe DFUs were enrolled and therapized by TTT surgery in this cross-sectional and experimental study. Major clinical outcomes including limb salvage rate and antibiotics usage rate were investigated. Ten clinical characteristics and laboratory features of glucose metabolism and kidney function were statistically analyzed. Blood samples from 6 key time points of TTT surgery were collected for label-free proteomics and clinical immune biomarker analysis. Besides, tissue samples from 3 key time points were for spatially resolved metabolomics and transcriptomics analysis, as well as applied to validate the key TTT-regulated molecules by RT-qPCR. RESULTS: Notably, 64.7% of patients did not use antibiotics during the entire TTT surgery. TTT surgery can achieve a high limb salvage rate of 92.6% in patients with unilateral or bilateral DFUs. Pathway analysis of a total of 252 differentially expressed proteins (DEPs) from the proteomic revealed that the immune response induced by TTT surgery at different stages was first comprehensively verified through multi-omics combined with immune biomarker analysis. The function of upward transport was activating the systemic immune response, and wound healing occurs with downward transport. The spatial metabolic characteristics of skin tissue from patients with DFUs indicated downregulated levels of stearoylcarnitine and the glycerophospholipid metabolism pathway in skin tissue from patients with severe DFUs. Finally, the expressions of PRNP (prion protein) to activate the immune response, PLCB3 (PLCB3, phospholipase C beta 3) and VE-cadherin to play roles in neovascularization, and PPDPF (pancreatic progenitor cell differentiation and proliferation factor), LAMC2 (laminin subunit gamma 2) and SPRR2G (small proline rich protein 2G) to facilitate the developmental process mainly keratinocyte differentiation were statistically significant in skin tissues through transcriptomic and RT-qPCR analysis. CONCLUSION: Tibial cortex transverse transport (TTT) surgery demonstrates favorable outcomes for patients with severe type 2 DFUs by activating a systemic immune response, contributing to anti-infection, ulcer recurrence, and the limb salvage rate for unilateral or bilateral DFUs. The specific clinical immune responses, candidate proteins, genes, and metabolic characteristics provide directions for in-depth mechanistic research on TTT surgery. Further research and public awareness are needed to optimize TTT surgery in patients with severe type 2 DFUs.

Gambogenic acid induces apoptosis via upregulation of Noxa in oral squamous cell carcinoma.

Gambogenic acid (GNA), a bioactive compound derived from the resin of Garcinia hanburyi, has demonstrated significant antitumor properties. However, its mechanisms of action in oral squamous cell carcinoma (OSCC) remain largely unclear. This study aimed to elucidate the apoptotic effects of GNA on OSCC cell lines CAL-27 and SCC-15. Our results indicated that GNA induced apoptosis by upregulating the pro-apoptotic protein Noxa. Mechanistic investigations revealed that GNA treatment led to the generation of reactive oxygen species (ROS), which activated endoplasmic reticulum (ER) stress, culminating in cell apoptosis. Inhibition of ROS production and ER stress pathways significantly mitigated GNA-induced Noxa upregulation and subsequent apoptosis. Furthermore, in vivo studies using a murine xenograft model demonstrated that GNA administration effectively inhibited the growth of CAL-27 tumors. Collectively, these findings underscore GNA's potential as a therapeutic agent for the treatment of OSCC.

Identification of pancreatic adenocarcinoma immune subtype associated with tumor neoantigen from aberrant alternative splicing.

Background: Pancreatic adenocarcinoma (PAAD) is referred to as an immunologically "cold" tumor that responds poorly to immunotherapy. A fundamental theory that explains the low immunogenicity of PAAD is the dramatically low tumor mutation burden (TMB) of PAAD tumors, which fails to induce sufficient immune response. Alternative splicing of pre-mRNA, which could alter the proteomic diversity of many cancers, has been reported to be involved in neoantigen production. Therefore, we aim to identify novel PAAD antigens and immune subtypes through systematic bioinformatics research. Methods: Data for splicing analysis were downloaded from The Cancer Genome Atlas (TCGA) SpliceSeq database. Among the available algorithms, we chose CIBERSORT to evaluate the immune cell distribution among PAADs. The TCGA-PAAD expression matrix was used to construct a co-expression network. Single-cell analysis was performed based on the Seurat workflow. Results: Integrated analysis of aberrantly upregulated genes, alternatively spliced genes, genes associated with nonsense-mediated RNA decay (NMD) factors, antigen presentation and overall survival (OS) in TCGA-PAAD revealed that PLEC is a promising neoantigen for PAAD-targeted therapy. We identified a C2 TCGA-PAAD subtype that had better prognosis and more CD8+ T-cell infiltration. We propose a novel immune subtyping system for PAAD to indicate patient prognosis and opportunities for immunotherapy, such as immune checkpoint (ICP) inhibitors. Conclusions: In conclusion, the present study used a transcriptome-guided approach to screen neoantigen candidates based on alternative splicing, NMD factors, and antigen-presenting signatures for PAAD. A prognosis model with guidance of immunotherapy will aid in patient selection for appropriate treatment.

BCL6 overexpression in CD4+ T cells induces Tfh-like transdifferentiation and enhances antitumor efficiency of CAR-T therapy in pancreatic cancer.

PDAC is a typical "cold tumor" characterized by low immune cell infiltration and a suppressive immune microenvironment. We previously observed the existence of a rare group of follicular helper T cells (Tfh) that could enhance antitumor immune responses by recruiting other immune cells in PDAC. In this study, we ectopically expressed BCL6 in CD4+ T cells, and successfully induced Tfh-like transdifferentiation in vitro. This strategy provided abundant Tfh-like cells (iTfhs) that can recruit CD8+ T cells like endogenous Tfhs. Subsequently, Chimeric Antigen Receptors (CARs) against both MSL (Mesothelin) and EPHA2 (Ephrin receptor A2) were used to modify iTfh cells, and the CAR-iTfh cells significantly improved infiltration and antitumor cytotoxicity of co-cultured CD8+ T cells. After that, combinatory administration of CAR-iTfh & CAR-CD8 T cell therapy displayed a better effect in repressing the PDAC tumors in xenograft mouse models, compared to conventional CAR-CD4 & CAR-CD8 combinations, and the models received the CAR-iTfh & CAR-CD8 T cells displayed a significantly improved survival rate. Our study revealed the plasticity of Thelper differentiation, expanded the source of Tfh-like cells for cell therapy, and demonstrated a novel and potentially more efficient cellular composition for CAR-T therapy.

Comparison among different preclinical models derived from the same patient with a non-functional pancreatic neuroendocrine tumor.

Pancreatic neuroendocrine tumors are the second most common tumors of the pancreas, and approximately half of patients are diagnosed with liver metastases. Currently, the improvement in the efficacy of relevant treatment methods is still limited. Therefore, there is an urgent need for in-depth research on the molecular biological mechanism of pancreatic neuroendocrine tumors. However, due to their relatively inert biology, preclinical models are extremely scarce. Here, the patient-derived organoid, and patient-derived xenograft were successfully constructed. These two models and the previously constructed cell line named SPNE1 all derived from the same patient with a grade 3 non-functional pancreatic neuroendocrine tumor, providing new tumor modeling platforms, and characterized using immunohistochemistry, whole-exome sequencing, and single-cell transcriptome sequencing. Combined with a tumor formation experiment in immunodeficient mice, we selected the model that most closely recapitulated the parental tumor. Overall, the patient-derived xenograft model most closely resembled human tumor tissue.

MEN1 Deficiency-Driven Activation of the ß-Catenin-MGMT Axis Promotes Pancreatic Neuroendocrine Tumor Growth and Confers Temozolomide Resistance.

O6-methylguanine DNA methyltransferase (MGMT) removes alkyl adducts from the guanine O6 position (O6-MG) and repairs DNA damage. High MGMT expression results in poor response to temozolomide (TMZ). However, the biological importance of MGMT and the mechanism underlying its high expression in pancreatic neuroendocrine tumors (PanNETs) remain elusive. Here, it is found that MGMT expression is highly elevated in PanNET tissues compared with paired normal tissues and negatively associated with progression-free survival (PFS) time in patients with PanNETs. Knocking out MGMT inhibits cancer cell growth in vitro and in vivo. Ectopic MEN1 expression suppresses MGMT transcription in a manner that depends on ß-Catenin nuclear export and degradation. The Leucine 267 residue of MEN1 is crucial for regulating ß-Catenin-MGMT axis activation and chemosensitivity to TMZ. Interference with ß-Catenin re-sensitizes tumor cells to TMZ and significantly reduces the cytotoxic effects of high-dose TMZ treatment, and MGMT overexpression counteracts the effects of ß-Catenin deficiency. This study reveals the biological importance of MGMT and a new mechanism by which MEN1 deficiency regulates its expression, thus providing a potential combinational strategy for treating patients with TMZ-resistant PanNETs.