Nuclear PKM2 binds pre-mRNA at folded G-quadruplexes and reveals their gene regulatory role.

Nuclear localization of the metabolic enzyme PKM2 is widely observed in various cancer types. We identify nuclear PKM2 as a non-canonical RNA-binding protein (RBP) that specifically interacts with folded RNA G-quadruplex (rG4) structures in precursor mRNAs (pre-mRNAs). PKM2 occupancy at rG4s prevents the binding of repressive RBPs, such as HNRNPF, and promotes the expression of rG4-containing pre-mRNAs (the "rG4ome"). We observe an upregulation of the rG4ome during epithelial-to-mesenchymal transition and a negative correlation of rG4 abundance with patient survival in different cancer types. By preventing the nuclear accumulation of PKM2, we could repress the rG4ome in triple-negative breast cancer cells and reduce migration and invasion of cancer cells in vitro and in xenograft mouse models. Our data suggest that the balance of folded and unfolded rG4s controlled by RBPs impacts gene expression during tumor progression.

NUSAP1 promotes pancreatic ductal adenocarcinoma progression by drives the epithelial-mesenchymal transition and reduces AMPK phosphorylation.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis, and its molecular mechanisms are unclear. Nucleolar and spindle-associated protein 1 (NUSAP1), an indispensable mitotic regulator, has been reported to be involved in the development of several types of tumors. The biological function and molecular mechanism of NUSAP1 in PDAC remain controversial. This study explored the effects and mechanism of NUSAP1 in PDAC. METHODS: Differentially expressed genes (DEGs) were screened. A protein‒protein interaction (PPI) network was constructed to identify hub genes. Experimental studies and tissue microarray (TMA) analysis were performed to investigate the effects of NUSAP1 in PDAC and explore its mechanism. RESULTS: Network analysis revealed that NUSAP1 is an essential hub gene in the PDAC transcriptome. Genome heterogeneity analysis revealed that NUSAP1 is related to tumor mutation burden (TMB), loss of heterozygosity (LOH) and homologous recombination deficiency (HRD) in PDAC. NUSAP1 is correlated with the levels of infiltrating immune cells, such as B cells and CD8 T cells. High NUSAP1 expression was found in PDAC tissues and was associated with a poor patient prognosis. NUSAP1 promoted cancer cell proliferation, migration and invasion, drives the epithelial-mesenchymal transition and reduces AMPK phosphorylation. CONCLUSIONS: NUSAP1 is an essential hub gene that promotes PDAC progression and leads to a dismal prognosis by drives the epithelial-mesenchymal transition and reduces AMPK phosphorylation.

TRIM14 Inhibits cGAS Degradation Mediated by Selective Autophagy Receptor p62 to Promote Innate Immune Responses.

Cyclic GMP-AMP synthase (cGAS) is an essential DNA virus sensor that triggers type I interferon (IFN) signaling by producing cGAMP to initiate antiviral immunity. However, post-translational regulation of cGAS remains largely unknown. We report that K48-linked ubiquitination of cGAS is a recognition signal for p62-depdendent selective autophagic degradation. The induction of TRIM14 by type I IFN accelerates cGAS stabilization by recruiting USP14 to cleave the ubiquitin chains of cGAS at lysine (K) 414. Knockout of TRIM14 impairs herpes simplex virus type 1 (HSV-1)-triggered antiviral responses in a cGAS-dependent manner. Due to impaired type I IFN production, Trim14-/- mice are highly susceptible to lethal HSV-1 infection. Taken together, our findings reveal a positive feedback loop of cGAS signaling generated by TRIM14-USP14 and provide insights into the crosstalk between autophagy and type I IFN signaling in innate immunity.

USP38 Inhibits Type I Interferon Signaling by Editing TBK1 Ubiquitination through NLRP4 Signalosome.

TBK1 is a component of the type I interferon (IFN) signaling pathway, yet the mechanisms controlling its activity and degradation remain poorly understood. Here we report that USP38 negatively regulates type I IFN signaling by targeting the active form of TBK1 for degradation in vitro and in vivo. USP38 specifically cleaves K33-linked poly-ubiquitin chains from TBK1 at Lys670, and it allows for subsequent K48-linked ubiquitination at the same position mediated by DTX4 and TRIP. Knockdown or knockout of USP38 increases K33-linked ubiquitination, but it abrogates K48-linked ubiquitination and degradation of TBK1, thus enhancing type I IFN signaling. Our findings identify an essential role for USP38 in negatively regulating type I IFN signaling, and they provide insights into the mechanisms by which USP38 regulates TBK1 ubiquitination through the NLRP4 signalosome.

Functional editing of endogenous genes through rapid selection of cell pools (Rapid generation of endogenously tagged genes in Drosophila ovarian somatic sheath cells).

The combination of genome-editing and epitope tagging provides a powerful strategy to study proteins with high affinity and specificity while preserving their physiological expression patterns. However, stably modifying endogenous genes in cells that do not allow for clonal selection has been challenging. Here, we present a simple and fast strategy to generate stable, endogenously tagged alleles in a non-transformed cell culture model. At the example of piwi in Drosophila ovarian somatic sheath cells, we show that this strategy enables the generation of an N-terminally tagged protein that emulates the expression level and subcellular localization of the wild type protein and forms functional Piwi-piRNA complexes. We further present a concise workflow to establish endogenously N-terminally and C-terminally tagged proteins, and knockout alleles through rapid selection of cell pools in fly and human models.

CRIP1 fosters MDSC trafficking and resets tumour microenvironment via facilitating NF-κB/p65 nuclear translocation in pancreatic ductal adenocarcinoma.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is among the most immunosuppressive tumour types. The tumour immune microenvironment (TIME) is largely driven by interactions between immune cells and heterogeneous tumour cells. Here, we aimed to investigate the mechanism of tumour cells in TIME formation and provide potential combination treatment strategies for PDAC patients based on genotypic heterogeneity. DESIGN: Highly multiplexed imaging mass cytometry, RNA sequencing, mass cytometry by time of flight and multiplex immunofluorescence staining were performed to identify the pro-oncogenic proteins associated with low immune activation in PDAC. An in vitro coculture system, an orthotopic PDAC allograft tumour model, flow cytometry and immunohistochemistry were used to explore the biological functions of cysteine-rich intestinal protein 1 (CRIP1) in tumour progression and TIME formation. RNA sequencing, mass spectrometry and chromatin immunoprecipitation were subsequently conducted to investigate the underlying mechanisms of CRIP1. RESULTS: Our results showed that CRIP1 was frequently upregulated in PDAC tissues with low immune activation. Elevated CRIP1 expression induced high levels of myeloid-derived suppressor cell (MDSC) infiltration and fostered an immunosuppressive tumour microenvironment. Mechanistically, we primarily showed that CRIP1 bound to nuclear factor kappa-B (NF-κB)/p65 and facilitated its nuclear translocation in an importin-dependent manner, leading to the transcriptional activation of CXCL1/5. PDAC-derived CXCL1/5 facilitated the chemotactic migration of MDSCs to drive immunosuppression. SX-682, an inhibitor of CXCR1/2, blocked tumour MDSC recruitment and enhanced T-cell activation. The combination of anti-PD-L1 therapy with SX-682 elicited increased CD8+T cell infiltration and potent antitumor activity in tumour-bearing mice with high CRIP1 expression. CONCLUSIONS: The CRIP1/NF-κB/CXCL axis is critical for triggering immune evasion and TIME formation in PDAC. Blockade of this signalling pathway prevents MDSC trafficking and thereby sensitises PDAC to immunotherapy.

Reappraisal of Tumor Deposit as a Prognostic Factor in Pancreatic Cancer.

PURPOSE: Tumor deposits (TDs) are discrete tumor nodules within the lymphatic drainage area of the primary tumor without histological evidence of lymph node tissue or identifiable vascular or neural structure. This study aims to analyze the prognostic impact of TDs in patients with pancreatic ductal adenocarcinoma (PDAC) and explore their potential role in staging system. METHODS: The prospectively maintained database from the Fudan University Shanghai Cancer Center was queried for patients undergoing resection for PDAC. Patients with TDs were matched by propensity score with those without TDs. The cumulative prevalence of recurrence was estimated using the cumulative incidence function. Overall survival was estimated using Kaplan-Meier curves. RESULTS: A total of 123 patients (9.7%) had TDs, of whom 108 were matched at a 1:3 ratio with 324 patients without TDs. The cumulative incidence of recurrence was significantly higher for TD-positive patients than TD-negative patients (P = 0.04). The median overall survival was significantly shorter for patients with TDs than for those without TDs (15.9 versus 21.8 months, P < 0.001). The presence of TDs attenuated the effect of lymph node metastasis on survival, with no significance between node-negative and node-positive subpopulations (P = 0.165). Patients with TDs had comparable survival to N2 patients without TDs (15.9 versus 17.1 months, P = 0.383). CONCLUSIONS: TD is an important prognostic factor for recurrence and survival in patients undergoing resection for PDAC. We suggest that patients presenting TDs be classified into the stage III category in the next edition of the staging system.

Mechanical Regulation of Redox Balance via the Induction of the PIN1/NRF2/ARE Axis in Pancreatic Cancer.

Pancreatic cancer is one of the most lethal malignancies. Desmoplastic stroma and metabolic reprogramming are two hallmarks of pancreatic cancer that support its malignant biological behaviors. However, the underlying mechanism by which the stroma maintain the redox balance remains unclear in pancreatic ductal adenocarcinoma (PDAC). Here, we demonstrated that the physical properties of the stroma could regulate the expression of PIN1 in pancreatic cancer cells. Moreover, we found that hard matrix-cultured pancreatic cancer cells induced the upregulation of PIN1 expression. Since PIN1 maintained redox balance via synergistic activation of NRF2 transcription, PIN1 promoted the expression of NRF2 to induce the expression of intracellular antioxidant response element (ARE)-driven genes. Consequently, the antioxidant stress ability of PDAC was increased, and the intracellular level of reactive oxygen species (ROS) was decreased. Thus, PIN1 is expected to be an important target for the treatment of PDAC, especially PDAC with an exuberant desmoplastic stroma.

Mitochondria-Related Transcriptome Characterization Associated with the Immune Microenvironment, Therapeutic Response and Survival Prediction in Pancreatic Cancer.

(1) Background: Pancreatic cancer (PC) is one of the most lethal tumors. Mitochondrial dysfunction has been reported to be involved in cancer development; however, its role in PC has remained unclear. (2) Methods: The differentially expressed NMGs were selected between PC and normal pancreatic tissue. The NMG-related prognostic signature was established by LASSO regression. A nomogram was developed based on the 12-gene signature combined with other significant pathological features. An extensive analysis of the 12 critical NMGs was performed in multiple dimensions. The expression of some key genes was verified in our external cohort. (3) Results: Mitochondria-related transcriptome features was obviously altered in PC compared with normal pancreas tissue. The 12-NMG signature showed good performance in predicting prognosis in various cohorts. The high- and low-risk groups exhibited notable diversity in gene mutation characteristics, biological characteristics, chemotherapy response, and the tumor immune microenvironment. Critical gene expression was demonstrated in our cohort at the mRNA and protein levels and in organelle localization. (4) Conclusions: Our study analyzed the mitochondrial molecular characterization of PC, proving the crucial role of NMGs in PC development. The established NMG signature helps classify patient subtypes in terms of prognosis prediction, treatment response, immunological features, and biological function, providing a potential therapeutic strategy targeting mitochondrial transcriptome characterization.

Rice SEPALLATA genes OsMADS5 and OsMADS34 cooperate to limit inflorescence branching by repressing the TERMINAL FLOWER1-like gene RCN4.

The spatiotemporal control of meristem identity is critical for determining inflorescence architecture, and thus yield, of cereal plants. However, the precise mechanisms underlying inflorescence and spikelet meristem determinacy in cereals are still largely unclear. We have generated loss-of-function and overexpression mutants of the paralogous OsMADS5 and OsMADS34 genes in rice (Oryza sativa), and analysed their panicle phenotypes. Using chromatin immunoprecipitation, electrophoretic mobility-shift and dual-luciferase assays, we have also identified RICE CENTRORADIALIS 4 (RCN4), a TFL1-like gene, as a direct downstream target of both OsMADS proteins, and have analysed RCN4 mutants. The osmads5 osmads34 mutant lines had significantly enhanced panicle branching with increased secondary, and even tertiary and quaternary, branches, compared to wild-type (WT) and osmads34 plants. The osmads34 mutant phenotype could largely be rescued by also knocking out RCN4. Moreover, transgenic panicles overexpressing RCN4 had significantly increased branching, and initiated development of c. 7× more spikelets than WT. Our results reveal a role for OsMADS5 in panicle development, and show that OsMADS5 and OsMADS34 play similar functions in limiting branching and promoting the transition to spikelet meristem identity, in part by repressing RCN4 expression. These findings provide new insights to better understand the molecular regulation of rice inflorescence architecture.

Comprehensive analysis of the prognosis and immune infiltration landscape of RNA methylation-related subtypes in pancreatic cancer.

BACKGROUND: RNA methylation refers to a form of methyl modification in RNA that modulates various epigenetic alterations. Mounting studies have focused on its potential mechanisms in cancer initiation and progression. However, the prognostic value and potential role of RNA methylation in the immune microenvironment of pancreatic cancer remain unclear. METHODS: Comprehensive bioinformatics analysis was performed to illuminate the expression profiles of RNA methylation modulators. In addition, the ConsensusClusterPlus algorithm was utilized to identify two remarkably different subtypes, and a feasible risk stratification method was established to accurately estimate prognosis. In addition, we validated our signature at the cytology and histology levels and conducted functional experiments to explore the biological functions of our key genes. RESULTS: Two subtypes with remarkable survival differences were identified by the consensus clustering algorithm. Cluster 2 tended to have higher expression levels of RNA methylation regulators and to be the high RNA methylation group. In addition, cluster 1 exhibited a significantly higher abundance of almost all immune cells and increased immune checkpoint expression compared to cluster 2. Chemotherapeutic sensitivity analysis indicated that there were significant differences in the sensitivity of four of the six drugs between different subgroups. Mutation investigation revealed a higher mutation burden and a higher number of mutations in cluster 2. An accurate and feasible risk stratification method was established based on the expression of key genes of each subtype. Patients with low risk scores exhibited longer survival times in one training (TCGA) and two validation cohorts (ICGC, GSE57495), with p values of 0.001, 0.0081, and 0.0042, respectively. In addition, our signature was further validated in a cohort from Fudan University Shanghai Cancer Center. The low-risk group exhibited higher immune cell abundance and immune checkpoint levels than the high-risk group. The characteristics of the low-risk group were consistent with those of cluster 1: higher stromal score, estimate score, and immune score and lower tumor purity. Additionally, cell function investigations suggested that knockdown of CDKN3 remarkably inhibited the proliferation and migration of pancreatic cancer cells. CONCLUSIONS: RNA methylation has a close correlation with prognosis, immune infiltration and therapy in pancreatic cancer. Our subtypes and risk stratification method can accurately predict prognosis and the efficacy of immune therapy and chemotherapy.

Overcoming chemoresistance by targeting reprogrammed metabolism: the Achilles' heel of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related death due to its late diagnosis that removes the opportunity for surgery and metabolic plasticity that leads to resistance to chemotherapy. Metabolic reprogramming related to glucose, lipid, and amino acid metabolism in PDAC not only enables the cancer to thrive and survive under hypovascular, nutrient-poor and hypoxic microenvironments, but also confers chemoresistance, which contributes to the poor prognosis of PDAC. In this review, we systematically elucidate the mechanism of chemotherapy resistance and the relationship of metabolic programming features with resistance to anticancer drugs in PDAC. Targeting the critical enzymes and/or transporters involved in glucose, lipid, and amino acid metabolism may be a promising approach to overcome chemoresistance in PDAC. Consequently, regulating metabolism could be used as a strategy against PDAC and could improve the prognosis of PDAC.

Circular RNA CircEYA3 induces energy production to promote pancreatic ductal adenocarcinoma progression through the miR-1294/c-Myc axis.

BACKGROUND: Extensive studies have demonstrated the pivotal roles of circular RNAs (circRNAs) in the occurrence and development of different human cancers. However, the expression and regulatory roles of circRNAs in pancreatic ductal adenocarcinoma (PDAC) are unclear. METHODS: CircEYA3 was explored based on Gene Expression Omnibus (GEO) dataset analysis. qRT-PCR was applied to determine the expression of circRNAs, miRNAs and mRNAs in PDAC cells and tissues. The biological roles of circEYA3 in vitro and in vivo were determined by performing a series of functional experiments. Further, dual luciferase reporter, fluorescence in situ hybridization (FISH), RNA pull-down assays, and RNA immunoprecipitation (RIP) assays were used to confirm the interaction of circEYA3 with miR-1294. RESULTS: CircEYA3 was elevated in PDAC tissues and cells, and a higher level of circEYA3 was significantly associated with a poorer prognosis in patients with PDAC. Functionally, circEYA3 increased energy production via ATP synthesis to promote PDAC progression in vitro and in vivo. Mechanistically, circEYA3 functions as an endogenous miR-1294 sponge to elevate c-Myc expression, thus exerting its oncogenic functions. CONCLUSION: CircEYA3 promotes the progression of PDAC through the miR-1294/c-Myc signalling axis, and circEYA3 may be an efficient molecular therapeutic target in PDAC.

Crosstalk between cancer-associated fibroblasts and immune cells in the tumor microenvironment: new findings and future perspectives.

Cancer-associated fibroblasts (CAFs), a stromal cell population with cell-of-origin, phenotypic and functional heterogeneity, are the most essential components of the tumor microenvironment (TME). Through multiple pathways, activated CAFs can promote tumor growth, angiogenesis, invasion and metastasis, along with extracellular matrix (ECM) remodeling and even chemoresistance. Numerous previous studies have confirmed the critical role of the interaction between CAFs and tumor cells in tumorigenesis and development. However, recently, the mutual effects of CAFs and the tumor immune microenvironment (TIME) have been identified as another key factor in promoting tumor progression. The TIME mainly consists of distinct immune cell populations in tumor islets and is highly associated with the antitumor immunological state in the TME. CAFs interact with tumor-infiltrating immune cells as well as other immune components within the TIME via the secretion of various cytokines, growth factors, chemokines, exosomes and other effector molecules, consequently shaping an immunosuppressive TME that enables cancer cells to evade surveillance of the immune system. In-depth studies of CAFs and immune microenvironment interactions, particularly the complicated mechanisms connecting CAFs with immune cells, might provide novel strategies for subsequent targeted immunotherapies. Herein, we shed light on recent advances regarding the direct and indirect crosstalk between CAFs and infiltrating immune cells and further summarize the possible immunoinhibitory mechanisms induced by CAFs in the TME. In addition, we present current related CAF-targeting immunotherapies and briefly describe some future perspectives on CAF research in the end.

Role of tumor mutation burden-related signatures in the prognosis and immune microenvironment of pancreatic ductal adenocarcinoma.

BACKGROUND: High tumor mutation burden (TMB) has gradually become a sensitive biomarker for predicting the response to immunotherapy in many cancers, including lung, bladder and head and neck cancers. However, whether high TMB predicts the response to immunotherapy and prognosis in pancreatic ductal adenocarcinoma (PDAC) remained obscure. Hence, it is significant to investigate the role of genes related to TMB (TRGs) in PDAC. METHODS: The transcriptome and mutation data of PDAC was downloaded from The Cancer Genome Atlas-Pancreatic Adenocarcinoma (TCGA). Five independent external datasets of PDAC were chosen to validate parts of our results. qRT-PCR and immunohistochemical staining were also performed to promote the reliability of this study. RESULTS: The median overall survival (OS) was significantly increased in TMB_low group compared with the counterpart with higher TMB score after tumor purity adjusted (P = 0.03). 718 differentially expressed TRGs were identified and functionally enriched in some oncogenic pathways. 67 TRGs were associated with OS in PDAC. A prognostic model for the OS was constructed and showed a high predictive accuracy (AUC = 0.849). We also found TMB score was associated with multiple immune components and signatures in tumor microenvironment. In addition, we identified a PDAC subgroup featured with TMBlowMicrosatellite instabilityhigh (MSIhigh) was associated with prolonged OS and a key molecule, ANKRD55, potentially mediating the survival benefits. CONCLUSION: This study analyzed the biological function, prognosis value, implications for mutation landscape and potential influence on immune microenvironment of TRGs in PDAC, which contributed to get aware of the role of TMB in PDAC. Future studies are expected to investigate how these TRGs regulate the initiation, development or repression of PDAC.

Clinical Effect of PRP with DPASB on Full-Thickness Rotator Cuff Tears and Its Role in VAS, SST, and Constant Scores of Patients.

BACKGROUND: The aim of the study is to probe the effects of platelet-rich plasma (PRP) plus double-row anchor suture bridge (DRASB) under shoulder arthroscopy on the postoperative VAS, SST and Constant scores, rotator cuff tendonbone healing, and re-tear of patients with full-thickness rotator cuff tear (RCT). METHODS: A total of 60 patients with full-thickness RCT treated in our institution from August 2019 to January 2020 were picked and assigned to either group A (n = 30) or group B (n = 30) on a voluntary basis. Group B received DRASB under shoulder arthroscopy, whereas group A underwent DRASB under shoulder arthroscopy plus PRP. We compared the curative effects of both groups. RESULTS: Week 2, 4, 8, 12 after surgery and 6 months after surgery, VAS scores of patients in both groups declined saliently, whereas SST and Constant scores elevated, and the decrease/increase amplitude of patients in group A was sharply higher than that in group B (p < 0.05). At T2 and T3, abduction 90° external rotation, abduction 90° internal rotation, abduction and anteflexion in both groups increased strikingly, and group A harbored a brilliantly higher increase than group B (p < 0.05). At T2 and T3, serum NO and IL-6 contents were prominently dwindled in both groups, and group A held a plainly higher decrease than group B (p < 0.05). At T3, in comparison to group B, the rotator cuff tendonbone healing rate and quality of life scores in group A were higher (p < 0.05), whereas retear rate was dramatically lower (p < 0.05). CONCLUSIONS: DRASB under shoulder arthroscopy plus PRP therapy can blatantly meliorate the curative effect of patients with full-thickness tear, improve the shoulder joint function and tendonbone healing rate, reduce the postoperative pain degree and the incidence of retear, and can be more broadly promoted and applied clinically.

Ferroptosis: At the Crossroad of Gemcitabine Resistance and Tumorigenesis in Pancreatic Cancer.

The overall five-year survival rate of pancreatic cancer has hardly changed in the past few decades (less than 10%) because of resistance to all known therapies, including chemotherapeutic drugs. In the past few decades, gemcitabine has been at the forefront of treatment for pancreatic ductal adenocarcinoma, but more strategies to combat drug resistance need to be explored. One promising possibility is ferroptosis, a form of a nonapoptotic cell death that depends on intracellular iron and occurs through the accumulation of lipid reactive oxygen species, which are significant in drug resistance. In this article, we reviewed gemcitabine-resistance mechanisms; assessed the relationship among ferroptosis, tumorigenesis and gemcitabine resistance, and explored a new treatment method for pancreatic cancer.

Localisation of PGK1 determines metabolic phenotype to balance metastasis and proliferation in patients with SMAD4-negative pancreatic cancer.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive type of GI tumour, and it possesses deregulated cellular energetics. Although recent advances in PDAC biology have led to the discovery of recurrent genetic mutations in Kras, TP53 and SMAD4, which are related to this disease, clinical application of the molecular phenotype of PDAC remains challenging. DESIGN: We combined molecular imaging technology (positron emission tomography/CT) and immunohistochemistry to evaluate the correlation between the maximum standardised uptake value and SMAD4 expression and examined the effect of SMAD4 on glycolysis through in vitro and in vivo experiments. Furthermore, we identified the effect of SMAD4 on metabolic reprogramming by metabolomics and glucose metabolism gene expression analyses. Dual luciferase reporter assays and chromatin immunoprecipitation were performed to identify whether SMAD4 functioned as a transcription factor for phosphoglycerate kinase 1 (PGK1) in PDAC cells. Proliferative and metastatic assays were performed to examine the effect of PGK1 on the malignant behaviour of PDAC. RESULTS: We provide compelling evidence that the glycolytic enzyme PGK1 is repressed by transforming growth factor-ß/SMAD4. Loss of SMAD4 induces PGK1 upregulation in PDAC, which enhances glycolysis and aggressive tumour behaviour. Notably, in SMAD4-negative PDAC, nuclear PGK1 preferentially drives cell metastasis via mitochondrial oxidative phosphorylation induction, whereas cytoplasmic PGK1 preferentially supports proliferation by functioning as a glycolytic enzyme. The PDAC progression pattern and distinct PGK1 localisation combine to predict overall survival and disease-free survival. CONCLUSION: PGK1 is a decisive oncogene in patients with SMAD4-negative PDAC and can be a target for the development of a therapeutic strategy for SMAD4-negative PDAC.

PARP inhibitors in pancreatic cancer: molecular mechanisms and clinical applications.

Pancreatic cancer is a highly lethal disease with a poor prognosis, and existing therapies offer only limited effectiveness. Mutation gene sequencing has shown several gene associations that may account for its carcinogenesis, revealing a promising research direction. Poly (ADP-ribose) polymerase (PARP) inhibitors target tumor cells with a homologous recombination repair (HRR) deficiency based on the concept of synthetic lethality. The most prominent target gene is BRCA, in which mutations were first identified in breast cancer and ovarian cancer. PARP inhibitors can trap the PARP-1 protein at a single-stranded break/DNA lesion and disrupt its catalytic cycle, ultimately leading to replication fork progression and consequent double-strand breaks. For tumor cells with BRCA mutations, HRR loss would result in cell death. Pancreatic cancer has also been reported to have a strong relationship with BRCA gene mutations, which indicates that pancreatic cancer patients may benefit from PARP inhibitors. Several clinical trials are being conducted and have begun to yield results. For example, the POLO (Pancreatic Cancer Olaparib Ongoing) trial has demonstrated that the median progression-free survival was observably longer in the olaparib group than in the placebo group. However, PARP inhibitor resistance has partially precluded their use in clinical applications, and the major mechanism underlying this resistance is the restoration of HRR. Therefore, determining how to use PARP inhibitors in more clinical applications and how to avoid adverse effects, as well as prognosis and treatment response biomarkers, require additional research. This review elaborates on future prospects for the application of PARP inhibitors in pancreatic cancer.

The Strain Ratio as Obtained by Endoscopic Ultrasonography Elastography Correlates With the Stroma Proportion and the Prognosis of Local Pancreatic Cancer.

OBJECTIVE: The aim of this study was to investigate the association of the strain ratio (SR) with clinicopathologic features and the prognostic value of the SR in local pancreatic cancer. BACKGROUND: The SR as obtained by endoscopic ultrasonography elastography is useful in the differential diagnosis of pancreatic diseases. However, its role in the prognostic prediction of pancreatic cancer remains unknown. METHODS: A total of 78 resected pancreatic cancer patients and 93 locally advanced pancreatic cancer (LAPC) patients were enrolled in this study according to the inclusion criteria. Masson trichrome staining was used to evaluate the stromal proportion. Survival rates were calculated according to the Kaplan-Meier method and were compared using the log rank test. Multivariate analysis was performed with a Cox regression model. RESULTS: The SR was positively associated with the stromal proportion of resected pancreatic cancer (R = 0.768, P < 0.001). High SR was more likely in males (P = 0.039) and was related to perineural invasion (P = 0.022). High SR predicted unfavorable overall survival (OS) relative to low SR (15.4 vs. 25.8 mo, P = 0.017). SR was confirmed as an independent prognostic factor for resected pancreatic cancer based on multivariate analysis (hazard ratio = 1.939, P = 0.020). For LAPC patients who received nab-paclitaxel and gemcitabine, high SR was associated with improved prognosis (OS: 14.9 vs. 11.6 mo, P = 0.045), but this positive association was not observed in patients treated with other gemcitabine-based regimens (OS: 10.7 vs. 12.4 mo, P = 0.478). CONCLUSIONS: A high SR as obtained by endoscopic ultrasonography elastography was associated with poor prognosis of resected pancreatic cancer but predicted improved survival for LAPC patients treated with the nab-paclitaxel and gemcitabine regimen.