Potential Therapeutic Target For Pancreatic Ductal Adenocarcinoma Research Articles

Isoleucyl-tRNA synthetase 2 promotes pancreatic ductal adenocarcinoma proliferation and metastasis by stabilizing β-catenin

Isoleucyl-tRNA synthetase 2 (IARS2), originally regarded as an enzyme ligating isoleucine to the corresponding tRNA, has been identified as an oncogene recently. However, its function in pancreatic ductal adenocarcinoma (PDAC) remains to be discovered. Here we explored the biological role of IARS2 in PDAC. Up-regulated IARS2 was found in PDAC tissues and cell lines. Kaplan–Meier survival analysis indicated a worse prognosis in patients with high IARS2 expression. CCK-8, EdU, and colony formation assays showed IARS2 overexpression enhanced PDAC proliferation, which was reduced by IARS2 knockdown. Meanwhile, IARS2 down-regulation inhibited PDAC metastasis by impeding epithelial–mesenchymal transition. These results were also supported by subcutaneous xenograft and metastasis assays in vivo. To figure out underlying mechanisms, differential and enrichment analyses were conducted and the WNT signaling pathway was discovered. Our results demonstrated that there was no significant relationship between the WNT signaling pathway key factor CTNNB1 and IARS2 at the transcription level. However, cycloheximide assays showed that IARS2 reduced the β-catenin degradation rate. IARS2 inhibited the phosphorylation of β-catenin at the Ser33/37 site and regulated downstream targets of WNT signaling including c-MYC, c-JUN, and MMP7. The enhancement of proliferation and metastasis caused by IARS2 could be reversed by MSAB, an agent that promotes β-catenin degradation. In summary, IARS2 facilitates PDAC proliferation and metastasis by stabilizing β-catenin, which leads to WNT/β-catenin activation. IARS2 serves as an underlying prognosis marker and a potential therapeutic target for PDAC.

Tumor-associated macrophages drive glycolysis through the IL-8/STAT3/GLUT3 signaling pathway in pancreatic cancer progression

Glycolytic metabolism is a hallmark of pancreatic ductal adenocarcinoma (PDAC), and tumor-associated stromal cells play important roles in tumor metabolism. We previously reported that tumor-associated macrophages (TAMs) facilitate PDAC progression. However, little is known about whether TAMs are involved in regulating glycolysis in PDAC. Here, we found a positive correlation between CD68+ TAM infiltration and FDG maximal standardized uptake (FDG SUVmax) on PET-CT images of PDAC. We discovered that the glycolytic gene set was prominently enriched in the high TAM infiltration group through Gene Set Enrichment Analysis using The Cancer Genome Atlas database. Mechanistically, TAMs secreted IL-8 to promote GLUT3 expression in PDAC cells, enhancing tumor glycolysis both in vitro and in vivo, whereas this effect could be blocked by the IL-8 receptor inhibitor reparixin. Furthermore, IL-8 promoted the translocation of phosphorylated STAT3 into the nucleus to activate the GLUT3 promoter. Overall, we demonstrated that TAMs boosted PDAC cell glycolysis through the IL-8/STAT3/GLUT3 signaling pathway. Our cumulative findings suggest that the abrogation of TAM-induced tumor glycolysis by reparixin might exhibit an antitumor impact and offer a potential therapeutic target for PDAC.

Abstract C042: Discovery of a core inflammatory gene network associated with poor prognosis and characterized immune infiltration pattern in pancreatic ductal adenocarcinoma

Abstract Introduction: Inflammation has a significant impact on the tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) and is closely associated with disease prognosis. However, the inflammation features and immune infiltration profiles vary greatly among patients. It is still unclear how inflammation is associated with PDAC prognosis, and contradictory findings have been reported frequently. Therefore, it is essential to explore the core inflammatory genes and the related immune infiltration pattern in PDAC. Method: We analyzed bulk RNA sequencing data of 183 PDAC patients from the Cancer Genome Altas by combining 104 inflammatory gene sets (IGSs, 3427 genes in total) from the Molecular Signatures Database. Firstly, we calculated the inflammatory gene expression matrix using the gene set variation analysis (GSVA). Secondly, consensus clustering was executed to evaluate the stability of clustering for the above matrix. Furthermore, the overall survival (OS) and differential expression analyses were used to screen for core inflammatory genes. Finally, immune infiltration pattern among groups were profiled with CIBERSORT. Results: The 183 PDAC patients were initially clustered into two distinct groups according to the consensus clustering of our formed GSVA inflammatory gene expression matrix. Group 1 (94 patients) exhibited evident inflammation features, while Group 2 (89 patients) displayed limited inflammation features. However, no significant difference in OS was observed (p=0.33). We hypothesized that there might be a core inflammatory gene network (CIGN) which is potently related to poor prognosis in PDAC, rather than the overall inflammation features reflected by the collection of all IGSs. Therefore, Group 1 was further clustered into two subgroups: Group 1A (61 patients, high inflammation features) and Group 1B (33 patients, medium). Interestingly, a strong association with poor prognosis was found for Group 1B (medium) (p=0.045), while patients from Group 1A (high) and Group 2 (limited) presented no significant difference in OS (p=0.98). Finally, we discovered a CIGN consisting of two inflammatory genes, PLAU and DCBLD2, which were upregulated in Group 1B and positively correlated with poor prognosis. This association was also validated with two other PDAC datasets. The built CIGN defined groups showed the greatest association with poor prognosis (p=0.0045). As for the immune infiltration pattern, CIGN group showed a higher accumulation of M0 macrophages and neutrophils compared to non-CIGN group, while CD8+ T cells infiltration in CIGN group was much lowerer, implying a more immune suppressive TME in CIGN patients. Conclusion: Despite the lack of association between overall inflammation features and prognosis in PDAC, a CIGN associated with poor prognosis was discovered in this work with a characterized immune infiltration pattern. The CIGN may serve as diagnosis markers and potential therapeutic targets for PDAC toward precision medicine. Fundings: Hong Kong Theme-based Scheme (T12-201/20-R) Citation Format: Liu Yang, Zheng Chen, Yalan Sheng, Debajyoti Chowdhury, Hiu Fung Yip, Shuangying Qiao, Meiheng Sun, Aiping Lu, Fangfei Li. Discovery of a core inflammatory gene network associated with poor prognosis and characterized immune infiltration pattern in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C042.

Role of glycosylation-related gene MGAT1 in pancreatic ductal adenocarcinoma.

pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with a very poor prognosis and a complex tumor microenvironment, which plays a key role in tumor progression and treatment resistance. Glycosylation plays an important role in processes such as cell signaling, immune response and protein stability. single-cell RNA sequencing data and spatial transcriptome data were obtained from GSE197177 and GSE224411, respectively, and RNA-seq data and survival information were obtained from UCSC Xena and TCGA. Multiple transcriptomic data were comprehensively analyzed to explore the role of glycosylation processes in tumor progression, and functional experiments were performed to assess the effects of MGAT1 overexpression on PDAC cell proliferation and migration. In PDAC tumor samples, the glycosylation level of macrophages was significantly higher than that of normal samples. MGAT1 was identified as a key glycosylation-related gene, and its high expression was associated with better patient prognosis. Overexpression of MGAT1 significantly inhibited the proliferation and migration of PDAC cells and affected intercellular interactions in the tumor microenvironment. MGAT1 plays an important role in PDAC by regulating glycosylation levels in macrophages, influencing tumor progression and improving prognosis.MGAT1 is a potential therapeutic target for PDAC and further studies are needed to develop targeted therapeutic strategies against MGAT1 to improve clinical outcomes.

Quercetin Attenuates Cancer‐Associated Fibroblast Activation via Tumor‐Stromal Interactions and Demonstrates Its Clinical Value in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a rapidly progressing malignancy with a poor prognosis. Quercetin is a flavonoid compound with various biological benefits that can be extracted from Chinese herbs or daily foods. Quercetin has anticancer properties in various types of cancers. However, its therapeutic effects and potential mechanisms in PDAC have not been investigated extensively. Here, we confirmed the therapeutic effect of quercetin in PDAC using a mouse model. Based on high‐throughput RNA sequencing (RNA‐seq) and bioinformatic analysis, we propose that quercetin is involved in stromal infiltration of PDAC. Quercetin attenuates the activation of cancer‐associated fibroblasts (CAFs) via tumor‐stromal interaction. Meanwhile, we have identified two quercetin‐related prognostic models for patients with PDAC. Finally, we proposed a downstream target of quercetin, the ITGB4 gene, which could be a potential therapeutic target for PDAC.

NAP1L5 facilitates pancreatic ductal adenocarcinoma progression via TRIM29-mediated ubiquitination of PHLPP1

Pancreatic ductal adenocarcinoma (PDAC) is considered one of the most aggressive solid tumours in humans. Despite its high mortality rate, effective targeted therapeutic strategies remain limited due to incomplete understanding of the underlying biological mechanisms. The NAP1L gene family has been implicated in the development and progression of various human tumours. However, the specific function and role of NAP1L5 (nucleosome assembly protein-like 5) in PDAC have not been fully elucidated. Therefore, in this study, we aimed to investigate the role of NAP1L5 in PDAC and explore the regulatory relationship between NAP1L5 and its potential downstream molecule PHLPP1 (PH domain Leucine-rich repeat Protein Phosphatase 1) in PDAC. Our study revealed that NAP1L5 is notably upregulated in PDAC. Moreover, both in vivo and in vitro experiments demonstrated that knockdown of NAP1L5 suppressed the proliferation of PDAC cells. Mechanistically, NAP1L5 was found to promote PDAC progression by activating the AKT/mTOR signalling pathway in a PHLPP1-dependent manner. Specifically, NAP1L5 binds to PHLPP1 and facilitates the ubiquitination-mediated degradation of PHLPP1, ultimately resulting in reduced PHLPP1 expression. Notably, TRIM29, recruited by NAP1L5, was found to be involved in facilitating K48-linked ubiquitination of PHLPP1. Our findings indicate that NAP1L5 overexpression promotes the proliferation of PDAC cells by inhibiting PHLPP1 expression. These novel insights suggest that NAP1L5 may serve as a potential therapeutic target for PDAC.

METTL3-mediated m6A methylation of PYGB facilitates pancreatic ductal adenocarcinoma progression through the activation of NF-κB signaling

Brain Type Glycogen Phosphorylase (PYGB) has been revealed to participate in the progression of multiple human cancers. Nevertheless, the clinical significance and biological function of PYGB in pancreatic ductal adenocarcinoma (PAAD) remains unclarified. This study first analyzed the expression pattern, diagnostic value, and prognostic significance of PYGB in PAAD using the TCGA database. Subsequently, western blot assessed the protein expression of genes in PAAD cells. The viability, apoptosis, migration, and invasion of PAAD cells were assessed by CCK-8, TUNEL, and Transwell assays. Finally, in vivo experiment evaluated the effect of PYGB on PAAD tumor growth and metastasis. Through our investigation, it was revealed that PYGB had extremely high expression in PAAD and predicted a worse prognosis in patients with PAAD. Besides, the aggressiveness of PAAD cells could be suppressed or enhanced by depleting or supplementing PYGB. In addition, we demonstrated that METTL3 enhanced the translation of PYGB mRNA in an m6A-YTHDF1-dependent manner. Moreover, PYGB was revealed to regulate the malignant behaviors of PAAD cells by the mediation of the NF-κB signaling. Finally, PYGB depletion suppressed the growth and distant metastasis of PAAD in vivo. To conclude, our results indicated that METTL3-mediated m6A modification of PYGB exerted the tumor-promotive effect on PAAD through NF-κB signaling, suggesting PYGB is a potential therapeutic target in PAAD.

The MyD88 inhibitor, ST2825, induces cell cycle arrest and apoptosis by suppressing the activation of the NF‑κB/AKT1/p21 pathway in pancreatic cancer.

NF‑κB activation occurs in the majority patients with pancreatic ductal adenocarcinoma (PDAC); however, directly targeting NF‑κB has proven unsuccessful, and recent studies have demonstrated a certain effect of the indirect inhibition of NF‑κB. Myeloid differentiation factor 88 (MyD88) is a common intermediate messenger for NF‑κB activation by inducers. In the present study, the level of MyD88 in PDAC was detected using a public database and a tissue chip. A specific inhibitor (ST2825) of MyD88 was used on PDAC cell lines. Flow cytometry was used to examine apoptosis and cell cycle progression. Transcriptome sequencing was used for ST2825‑treated PANC‑1 cells compared with untreated PANC‑1 cells. The levels of related factors were measured using reverse transcription‑quantitative PCR and western blot analysis. Chromatin immunoprecipitation, co‑immunoprecipitation, transcription factor assay and an NF‑κB phospho‑antibody array were performed to identify the detailed underlying mechanisms. Animal experiments were performed to verify the effects of ST2825 on PDAC, which were found in the invitro experiments. MyD88 was found to be overexpressed in PDAC. ST2825 induced the G2/M phase cell cycle arrest and apoptosis of PDAC cells. ST2825 inhibited MyD88 dimerization to inactivate the NF‑κB pathway. ST2825 inhibited AKT1 expression and induced p21 overexpression to induce G2/M phase cell cycle arrest and apoptosis by inhibiting NF‑κB transcriptional activity. NF‑κB activation, AKT1 overexpression or p21 knockdown partially reversed the effects of ST2825 in PDAC. On the whole, the findings of the present study demonstrate that ST2825 induces G2/M cell cycle arrest and apoptosis via the MyD88/NF‑κB/AKT1/p21 pathway in PDAC. MyD88 may thus serve as a potential therapeutic target in PDAC. ST2825 may serve as a novel agent for the targeted therapy of PDAC in the future.

ENO1 expression and Erk phosphorylation in PDAC and their effects on tumor cell apoptosis in a hypoxic microenvironment.

Hypoxia is an important feature of pancreatic ductal adenocarcinoma (PDAC). Previously, we found that hypoxia promotes ENO1 expression and PDAC invasion. However, the underlying molecular mechanism was remains unclear. The relationship between ENO1 expression and clinicopathological characteristics was analyzed in 84 patients with PADC. The effects of CoCl2-induced hypoxia and ENO1 downregulation on the apoptosis, invasion, and proliferation of PDAC cells were evaluated in vitro and in vivo. Hypoxia- and ENO1-induced gene expression was analyzed by transcriptomic sequencing. The prognosis of PDAC with high ENO1 expression was poor (P < 0.05). High ENO1 expression was closely associated with histological differentiation and tumor invasion in 84 PDAC cases (P < 0.05). Hypoxia increased ENO1 expression in PDAC and promoted its migration and invasion. Apoptotic cells and the apoptosis marker caspase-3 in the CoCl2-treated ENO1-sh group were significantly elevated (P < 0.05). Transcriptomic sequencing indicated that CoCl2-induced PDAC cells initiated MAPK signaling. Under hypoxic conditions, PDAC cells upregulated ENO1 expression, thereby accelerating ERK phosphorylation and inhibiting apoptosis (P < 0.05). Consistent results were also observed in a PDAC-bearing mouse hindlimb ischemia model. Hypoxia-induced ENO1 expression promotes ERK phosphorylation and inhibits apoptosis, thus leading to PDAC survival and invasion. These results suggest that ENO1 is a potential therapeutic target for PDAC.

Abstract B042: Inhibition of CPSF3 attenuates pancreatic cancer cell proliferation through disruption of histone processing

Abstract Treatment regimens of pancreatic ductal adenocarcinoma (PDAC) are limited and minimally effective which potentiates the importance of discovering novel potential drug targets. We discovered widespread dysregulation of alternative polyadenylation (APA) in PDAC patients. APA is a pre-mRNA processing mechanism that generates mRNAs isoforms with distinct 3’ untranslated regions (3’UTRs). These isoforms contribute to the expression and function of mRNAs and proteins. Our recent study revealed that APA alterations in PDAC drive dysregulation of PDAC-promoting genes and present a reliable prognostic marker. APA is controlled by a suite of genes, including cleavage and polyadenylation specificity factor 3 (CPSF3). Because CPSF3 is the endonuclease that catalyzes mRNA cleavage, we here sought to target CPSF3 in PDAC. We show that CPSF3 expression is significantly upregulated and associated with unfavorable prognosis in PDAC patients. Loss of CPSF3 decreases PDAC cell proliferation, clonogenicity and tumor growth. We show that CPSF3 loss causes APA changes of tumor-associated genes and validate the tumor suppressing activity of one APA-altered gene, FHL1. Using JTE-607, a chemical inhibitor of CPSF3, we find that PDAC cells are preferentially sensitive while non-transformed cell lines are resistant to CPSF3 inhibition. Notably, we show that JTE-607 decreases proliferation-dependent histone expression and disrupts nucleosome assembly. Finally, we find that JTE-607 arrests cells in early to mid S-phase of the cell cycle, resembling histone defect-induced cell cycle arrest. Overall, we reveal alternative polyadenylation and histone processing as two distinct mechanisms underlying CPSF3-induced attenuation of cell proliferation and identify CPSF3 as a potential therapeutic target in PDAC. Citation Format: Abdulrahman A. Alahmari, Aditi Chaubey, Arwen Tisdale, Carla Schwarz, Abigail Cornwell, Kathryn Maraszek, Emily Paterson, Minsuh Kim, Swati Venkat, Eduardo Cortes Gomez, Jianmin Wang, Katerina Gurova, Michael E. Feigin. Inhibition of CPSF3 attenuates pancreatic cancer cell proliferation through disruption of histone processing [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B042.

Investigation of clinical application of claudin 18 isoform 2 in pancreatic ductal adenocarcinoma: A retrospective analysis of 302 chinese patients.

The malignancy of pancreatic ductal adenocarcinoma (PDAC) results from high frequency of recurrence and limited effective therapies. Targeted therapy is a promising treatment in multiple solid tumours. A new target, claudin 18 isoform 2 (CLDN18.2) was discovered in gastric and pancreatic adenocarcinoma, but more clinical evaluations of CLDN18.2 are still needed. Several CLDN18.2-targeted drugs have already been in procedure of clinical trials. Therefore, the present study aimed to explore the expression and clinical value of CLDN18.2 in PDAC by immunohistochemistry. A microarray cohort of 302 PDAC specimens and a whole-slide cohort of randomized 84 PDAC specimens were constructed. In total, 56.52% (171/302) of PDAC patients showed diverse positivity for CLDN18.2, especially in highly differentiated PDAC. About eighty-two percent (62/75) highly- and 62.61% (72/115) intermediate-differentiated PDAC showed positive for CLDN18.2, while only 10.16% (6/59) low differentiated PDAC was positive for CLDN18.2. Besides, CLDN18.2 positivity was associated with several clinicopathological characteristics, including sex (P=0.001), smoking (P=0.006), abdominal pain (P=0.021), jaundice (P=0.010), pathological differentiation (P=0.001), common bile duct invasion (P=0.010), and M stage (P=0.003). CLDN18.2-positive expression also predicts an improved survival (P=0.032) but not progression free survival (P=0.460). However, CLDN18.2 is not an independent prognostic predictor. In conclusion, CLDN18.2 may be a potential therapeutic target for PDAC and the study supplies persuasive pathological evidence for CLDN18.2-targeted therapy on PDAC patients.

Abstract 5491: Targeting importin-YAP axis in pancreatic ductal adenocarcinoma

Abstract Background: To date, pancreatic ductal adenocarcinoma (PDAC) remains to have a dismal prognosis, with a 5-year survival rate of only 10%, which brings out an imperative to develop new therapeutic strategies to improve patient outcome. Recently, aberrant nucleocytoplasmic transport machinery in cancer cells has emerged as a rational therapeutic target. We aim to validate the nuclear importin complex involved in the import of macromolecules across the nuclear membrane as a potential therapeutic target in PDAC. Methods: Tet-inducible shRNA and FDA-approved agent (Ivermectin) were used for the inhibition of importins. Cell death (apoptosis and pyroptosis) was detected by western blot. In vivo tumor growth of human and mouse PDAC cells was evaluated in immunocompetent and immunodeficient animal models. MTT assay was employed to evaluate the patient-derived organoid viability following drug treatment. Results: We found that PDAC cells/patients harbored unusually higher levels of importins. Inducible knockdown of importin-α2/α5 (KPNA2/KPNA1) or importin-β1 (KPNB1) strongly suppressed PDAC tumor growth and induced apoptosis and pyroptosis. Interestingly, the importin inhibitor Ivermectin (an FDA-approved antiparasitic agent) worked effectively in PDAC cells, patient-derived organoids and animal models. Mechanistically, we show that importins associate with YAP (the transcriptional coactivator of the Hippo pathway) and control its expression at mRNA levels. In line with these observations, the expression levels of importin-αs, importin-β1, and YAP are positively correlated in PDAC patients. Conclusion: Our study identifies the importin complex as a prognostic marker and therapeutic target for pancreatic cancer and is expected to provide preclinical evidence for the evaluation of Ivermectin in PDAC patients. Citation Format: Renya Zeng, Jixin Dong. Targeting importin-YAP axis in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5491.

Interleukin 6/gp130 axis promotes neural invasion in pancreatic cancer.

Nerve invasion (N-inv) is an important prognostic factor in pancreatic ductal adenocarcinoma (PDAC). Elucidation of circulating N-inv stimulators could provide deeper insights and novel perspectives for PDAC therapy. The interleukin (IL)-6/gp130 axis was evaluated in this study as a candidate N-inv stimulator. A human pancreatic cancer (PC) cell, Capan-1, was confirmed to have the stimulant activity of IL-6/gp130 axis through the evaluation of mRNA, cell surface protein and intracellular protein levels and chemotaxis and wound healing assay. The upregulation of IL-6/gp130 axis was evaluated using tumor-derived IL-6 level and intratumoral pSTAT3 expression in N-inv of murine sciatic nerves by intraneural injection of Capan-1 cell (N-inv model) and using resected pancreatic cancer tissue and clinical data from 46 PDAC patients. mRNA and protein expressions of IL-6 and IL-6 receptor were found in whole cell lysate and condition medium from PC cell. Cell surface protein expression of gp130 were clearly detected on PC cell. IL-6 promoted migration and chemotaxis of PC cell. Serum IL-6 and tumoral IL-6 mRNA levels in N-inv model mice were significantly higher than those in subcutaneous tumor mice (p = 0.004 and p = 0.002, respectively). Silencing of IL-6 and gp130 on PC cell and administration of an anti-IL-6 receptor antibody, tocilizumab, suppressed N-inv, compared to each control (p = 0.070, p = 0.118 and p = 0.122, respectively). In PDAC patients, the high-N-inv group showed poor prognosis (p =0.059) and elevated serum levels of IL-6 and C-reactive protein, synthesis of which is promoted by IL-6, compared to those in the low-N-inv group (p = 0.006 and p = 0.075, respectively). Tumoral gp130 expression at N-inv was higher than that in the primary pancreatic tumor (p = 0.026). Biological activity of IL-6/gp130 axis promoted N-inv in murine model and was upregulated in PDAC patients with severe N-inv. This study is the first evidence that the IL-6/gp130 axis offers a potential therapeutic target in PDAC with N-inv.

CircFARP1 enables cancer-associated fibroblasts to promote gemcitabine resistance in pancreatic cancer via the LIF/STAT3 axis

BackgroundCancer-associated fibroblasts (CAFs) are critically involved in gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC). However, the underlying mechanism by which CAFs promote chemotherapy resistance remains unexplored. Here, we explored the role of circRNAs in CAF-induced GEM resistance in PDAC.MethodscircRNA sequencing and quantitative real-time PCR (qRT–PCR) were utilized to screen CAF-specific circRNAs. The effects of CAF circFARP1 expression on GEM resistance in tumor cells were assessed in vitro and in vivo. RNA-seq, RNA pulldown, RNA immunoprecipitation, and luciferase reporter assays were used to screen the downstream target and underlying mechanism of circFARP1.ResultscircFARP1 (hsa_circ_0002557), a CAF-specific circRNA, was positively correlated with GEM chemoresistance and poor survival in an advanced PDAC cohort. Silencing or overexpressing circFARP1 in CAFs altered the ability of CAFs to induce tumor cell stemness and GEM resistance via leukemia inhibitory factor (LIF). Mechanistically, we found that circFARP1 directly binds with caveolin 1 (CAV1) and blocks the interaction of CAV1 and the E3 ubiquitin-protein ligase zinc and ring finger 1 (ZNRF1) to inhibit CAV1 degradation, which enhances LIF secretion. In addition, circFARP1 upregulated LIF expression by sponging miR-660-3p. Moreover, high circFARP1 levels were positively correlated with elevated serum LIF levels in PDAC and poor patient survival. Decreasing circFARP1 levels and neutralizing LIF significantly suppressed PDAC growth and GEM resistance in patient-derived xenograft models.ConclusionsThe circFARP1/CAV1/miR-660-3p/LIF axis is critical for CAF-induced GEM resistance in PDAC. Hence, circFARP1 may be a potential therapeutic target for PDAC.

Prognostic Implications of an Autophagy-related Gene Signature in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is difficult to diagnose and resistant to therapy and has a poor prognosis. Autophagy plays a vital role in PDAC development and progression. This study aimed to establish an autophagy-related gene (ARG) signature to predict the prognosis of patients with PDAC. The expression profiles of PDAC and healthy pancreatic tissues were obtained from The Cancer Genome of Atlas (TCGA) and GTEx (Genotype-Tissue Expression) databases, respectively. Univariate and multivariate Cox regression analyses were performed on differentially expressed ARGs to identify the optimal prognosis-related genes. A total of 73 ARGs demonstrated significant differences in expression levels between PDAC and healthy pancreatic tissues. Several pathways that play crucial roles in biological processes were identified via enrichment analyses. Furthermore, an ARG signature was established based on overall survival-related ARGs (CASP4, BAK1, PIK3R4, CASP8, BIRC5, RPTOR, and CAPN1) using least absolute shrinkage and selection operator (LASSO) regression. Cox regression analysis confirmed that the 7-gene signature was an independent prognostic factor for patients with PDAC (P<0.001). In addition, the GSE21501 and GSE28735 datasets were used to validate the predictive value of the prognostic model for PDAC. We also constructed a clinical nomogram with a concordance index of 0.712 to predict the overall survival of patients by integrating clinical characteristics and the ARG signature. Calibration curves substantiated fine concordance between nomogram prediction and actual observation. We constructed a new ARG-related prognostic model, which can be a prognostic biomarker and offers insights into identifying potential therapeutic targets for PDAC.

MicroRNAs in Pancreatic Cancer and Chemoresistance.

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading malignancies affecting human health, largely because of the development of resistance to chemotherapy/radiotherapy. There are many mechanisms that mediate the development of drug resistance, such as the transport of antineoplastic agents into cells, shifts in energy metabolism and environment, antineoplastic agent-induced DNA damage, and genetic mutations. MicroRNAs are short, noncoding RNAs that are 20 to 24 nucleotides in length and serve several biological functions. They bind to the 3'-untranslated regions of target genes and induce target degradation or translational inhibition. MicroRNAs can regulate several target genes and mediate PDAC chemotherapy/radiotherapy resistance. The detection of novel microRNAs would not only reveal the molecular mechanisms of PDAC and resistance to chemotherapy/radiotherapy but also provide new approaches to PDAC therapy. MicroRNAs are thus potential therapeutic targets for PDAC and might be essential in uncovering new mechanisms of the disease.

Upregulation of KLK8 Predicts Poor Prognosis in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a growing cause of cancer-related mortality worldwide. Kallikrein-related peptidase 8 (KLK8) has potential clinical values in many cancers. However, the clinicopathological significances of KLK8 in PDAC remain unknown. We explored the relationship of KLK8 to clinicopathological features of PDAC based on public databases. KLK8 expression was examined in human PDAC tissues. Cell proliferation and apoptosis were evaluated in KLK8-overexpressed human pancreatic cancer cell lines Mia-paca-2 and Panc-1. The related signaling pathways of KLK8 involved in pancreatic cancer progression were analyzed by gene set enrichment analysis (GSEA) and further verified in in vitro studies. We found that KLK8 was up-regulated in tumor tissues in the TCGA-PAAD cohort, and was an independent prognostic factor for both overall survival and disease-free survival of PDAC. KLK8 mRNA and protein expressions were increased in PDAC tissues compared with para-cancerous pancreas. KLK8 overexpression exerted pro-proliferation and anti-apoptotic functions in Mia-paca-2 and Panc-1 cells. GSEA analysis showed that KLK8 was positively associated with PI3K-Akt-mTOR and Notch pathways. KLK8-induced pro-proliferation and anti-apoptotic effects in Mia-paca-2 and Panc-1 cells were attenuated by inhibitors for PI3K, Akt, and mTOR, but not by inhibitor for Notch. Furthermore, overexpression of KLK8 in Mia-paca-2 and Panc-1 cells significantly increased epidermal growth factor (EGF) levels in the culture media. EGF receptor (EGFR) inhibitor could block KLK8-induced activation of PI3K/Akt/mTOR pathway and attenuate pro-proliferation and anti-apoptotic of KLK8 in Mia-paca-2 and Panc-1 cells. In conclusion, KLK8 overexpression exerts pro-proliferation and anti-apoptotic functions in pancreatic cancer cells via EGF signaling-dependent activation of PI3K/Akt/mTOR pathway. Upregulated KLK8 in PDAC predicts poor prognosis and may be a potential therapeutic target for PDAC.

Single-cell RNA sequencing reveals that targeting HSP90 suppresses PDAC progression by restraining mitochondrial bioenergetics

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, which lacks effective treatment strategies. There is an urgent need for the development of new strategies for PDAC therapy. The genetic and phenotypic heterogeneity of PDAC cancer cell populations poses further challenges in the clinical management of PDAC. In this study, we performed single-cell RNA sequencing to characterize PDAC tumors from KPC mice. Functional studies and clinical analysis showed that PDAC cluster 2 cells with highly Hsp90 expression is much more aggressive than the other clusters. Genetic and pharmacologic inhibition of Hsp90 impaired tumor cell growth both in vitro and in vivo. Further mechanistic study revealed that HSP90 inhibition disrupted the interaction between HSP90 and OPA1, leading to a reduction in mitochondrial cristae amount and mitochondrial energy production. Collectively, our study reveals that HSP90 might be a potential therapeutic target for PDAC.

CEACAM7 Is an Effective Target for CAR T-cell Therapy of Pancreatic Ductal Adenocarcinoma.

To investigate whether CEACAM7 represents a novel therapeutic target for treating pancreatic ductal adenocarcinoma (PDAC) and to generate CEACAM7-targeting CAR T cells to test this hypothesis. We identified CEACAM7 (CGM2), a member of the CEA family of proteins with expression restricted to the colon and pancreas, as a potential CAR T-cell target for PDAC. We probed a panel of PDAC tumor sections as well as patient-derived PDAC cell cultures for CEACAM7 expression. We generated CAR-targeting CEACAM7, and assessed antitumor efficacy of CEACAM7 CAR T cells using in vitro and in vivo models. We show here that CEACAM7 is expressed in a large subset of PDAC tumors, with low to undetectable expression in all normal tissues tested. CEACAM7 is also expressed in primary PDAC cultures isolated from patient-derived tumors, with high expression within the cancer stem cell-enriched subset. CAR T cells targeting CEACAM7 are capable of targeting antigen-expressing tumor cells, and mediate remission in patient-derived xenograft tumors. We identify CEACAM7 as a potential therapeutic target in PDAC and describe the development of CEACAM7-targeted CAR T cells with efficacy against PDAC.

KLHDC7B-DT aggravates pancreatic ductal adenocarcinoma development via inducing cross-talk between cancer cells and macrophages.

Tumor microenvironment (TME) exerts key roles in pancreatic ductal adenocarcinoma (PDAC) development. However, the factors regulating the cross-talk between PDAC cells and TME are largely unknown. In the present study, we identified a long noncoding RNA (lncRNA) KLHDC7B divergent transcript (KLHDC7B-DT), which was up-regulated in PDAC and correlated with poor survival of PDAC patients. Functional assays demonstrated that KLHDC7B-DT enhanced PDAC cell proliferation, migration, and invasion. Mechanistically, KLHDC7B-DT was found to directly bind IL-6 promoter, induce open chromatin structure at IL-6 promoter region, activate IL-6 transcription, and up-regulate IL-6 expression and secretion. The expression of KLHDC7B-DT was positively correlated with IL-6 in PDAC tissues. Via inducing IL-6 secretion, KLHDC7B-DT activated STAT3 signaling in PDAC cells in an autocrine manner. Furthermore, KLHDC7B-DT also activated STAT3 signaling in macrophages in a paracrine manner, which induced macrophage M2 polarization. KLHDC7B-DT overexpressed PDAC cells-primed macrophages promoted PDAC cell proliferation, migration, and invasion. Blocking IL-6/STAT3 signaling reversed the effects of KLHDC7B-DT on macrophage M2 polarization and PDAC cell proliferation, migration, and invasion. In conclusion, KLHDC7B-DT enhanced malignant behaviors of PDAC cells via IL-6-induced macrophage M2 polarization and IL-6-activated STAT3 signaling in PDAC cells. The cross-talk between PDAC cells and macrophages induced by KLHDC7B-DT represents potential therapeutic target for PDAC.