Pancreatic Ductal Adenocarcinoma Metastasis Research Articles

Prognostic effect of CD73 in pancreatic ductal adenocarcinoma for disease-free survival after radical surgery.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with a high potency of metastasis or recurrence after radical resection. Effective predictors for metastasis and recurrence postoperatively were dominant for the development of systemic adjuvant treatment regimens. The ATP hydrolase correlated gene CD73 was described as a promoter in tumor growth and immune escape of PDAC. However, there lacked research focused on the role of CD73 in PDAC metastasis. This study aimed to investigate the expression of CD73 in PDAC patients with different outcomes as well as the prognostic effect of CD73 for disease-free survival (DFS). The expression level of CD73 in cancerous samples from 301 PDAC patients was evaluated by immunohistochemistry (IHC) and translated into a histochemistry score (H-score) by the HALO analysis system. Then, the CD73 H-score was involved in multivariate Cox regression along with other clinicopathological characteristics to find independent prognostic factors for DFS. Finally, a nomogram was constructed based on those independent prognostic factors for DFS prediction. Higher CD73 expression was found in PDAC patients with tumor metastasis postoperatively. Meanwhile, higher CD73 expressions were also investigated in PDAC patients diagnosed with advanced N stage and T stage. Furthermore, CD73 H-score along with tumor margin status, CA19-9, 8th N stage, and adjuvant chemotherapy was indicated as independent prognostic factors for DFS in PDAC patients. The nomogram based on these factors predicted DFS in a good manner. CD73 was associated with PDAC metastasis and served as an effective prognostic factor for DFS in PDAC patients after radical surgery.

The Cell Biology of Metastatic Invasion in Pancreatic Cancer: Updates and Mechanistic Insights

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related mortality worldwide. This is largely due to the lack of routine screening protocols, an absence of symptoms in early-stage disease leading to late detection, and a paucity of effective treatment options. Critically, the majority of patients either present with metastatic disease or rapidly develop metastatic disease. Thus, there is an urgent need to deepen our understanding of metastasis in PDAC. During metastasis, tumor cells escape from the primary tumor, enter the circulation, and travel to a distant site to form a secondary tumor. In order to accomplish this relatively rare event, tumor cells develop an enhanced ability to detach from the primary tumor, migrate into the surrounding matrix, and invade across the basement membrane. In addition, cancer cells interact with the various cell types and matrix proteins that comprise the tumor microenvironment, with some of these factors working to promote metastasis and others working to suppress it. In PDAC, many of these processes are not well understood. The purpose of this review is to highlight recent advances in the cell biology of the early steps of the metastatic cascade in pancreatic cancer. Specifically, we will examine the regulation of epithelial-to-mesenchymal transition (EMT) in PDAC and its requirement for metastasis, summarize our understanding of how PDAC cells invade and degrade the surrounding matrix, and discuss how migration and adhesion dynamics are regulated in PDAC to optimize cancer cell motility. In addition, the role of the tumor microenvironment in PDAC will also be discussed for each of these invasive processes.

Abstract 4830: Uncoupling protein 2 (UCP2) loss of function mediates PDAC tumor suppression by mitochondrial fusion

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a dependence on highly active mitochondria to grow and metastasize. We previously found that mitochondrial fusion suppressed PDAC growth and metastasis, leading to improved survival in a preclinical model. The tumor suppressive mechanisms of mitochondrial fusion remain unclear, and thus we explored the role of redox homeostasis through uncoupling protein 2 (UCP2). Methods/Results: Murine pancreatic cancer cells (KPC) with enhanced mitochondrial fusion (sgDrp1) exhibited higher levels of mitochondrial ROS compared to controls targeting GFP (sgGFP), suggesting altered redox homeostasis. We performed RNAseq on these two cell lines and found that sgDRP1 cells exhibited reduced levels of UCP2. The UCP2 protein is known to have indirect antioxidant effects by reducing mitochondrial reactive oxygen species via uncoupling of ATP production from the electron transport chain. We found that abrogating UCP2 in KPC cells reduced its capacity for OXPHOS. Moreover, rescue of UCP2 in sgDrp1 cells restored their mitochondrial activity. Conclusions: Mitochondrial fusion may suppress tumor growth and induce mitophagy by altering redox homeostasis. UCP2 may be a mediator of the tumor suppressive phenotype induced by mitochondrial fusion, thus linking mitochondrial dynamics and PDAC antioxidant strategies. Future Work: These results will be explored for their translation in vivo and the effects of pharmacological inhibition of UCP2, both in vitro and in vivo, via the specific inhibitor Genipin, will be explored. Citation Format: Ariana Carolina Acevedo-Diaz, Emily G. Caggiano, Meifang Yu, Cullen Taniguchi. Uncoupling protein 2 (UCP2) loss of function mediates PDAC tumor suppression by mitochondrial fusion. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4830.

RBFOX2 modulates a metastatic signature of alternative splicing in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is characterized by aggressive local invasion and metastatic spread, leading to high lethality. Although driver gene mutations during PDA progression are conserved, no specific mutation is correlated with the dissemination of metastases1–3. Here we analysed RNA splicing data of a large cohort of primary and metastatic PDA tumours to identify differentially spliced events that correlate with PDA progression. De novo motif analysis of these events detected enrichment of motifs with high similarity to the RBFOX2 motif. Overexpression of RBFOX2 in a patient-derived xenograft (PDX) metastatic PDA cell line drastically reduced the metastatic potential of these cells in vitro and in vivo, whereas depletion of RBFOX2 in primary pancreatic tumour cell lines increased the metastatic potential of these cells. These findings support the role of RBFOX2 as a potent metastatic suppressor in PDA. RNA-sequencing and splicing analysis of RBFOX2 target genes revealed enrichment of genes in the RHO GTPase pathways, suggesting a role of RBFOX2 splicing activity in cytoskeletal organization and focal adhesion formation. Modulation of RBFOX2-regulated splicing events, such as via myosin phosphatase RHO-interacting protein (MPRIP), is associated with PDA metastases, altered cytoskeletal organization and the induction of focal adhesion formation. Our results implicate the splicing-regulatory function of RBFOX2 as a tumour suppressor in PDA and suggest a therapeutic approach for metastatic PDA.

The platelet pannexin 1-IL-1β axis orchestrates pancreatic ductal adenocarcinoma invasion and metastasis.

We aimed to investigate the protumor mechanisms of platelets in pancreatic ductal adenocarcinoma (PDAC). Serum samples were collected from 656 PDAC patients and 3105 healthy people, and a Panx1 knockout tumor model and an adoptive platelet transfusion mouse model were established. We showed that the blood platelet counts were not significantly different between stage III/IV and stage I/II patients, while the number of the CD41+/CD62P+ platelets was significantly elevated in stage III/IV patients, indicating that CD41+/CD62P+ platelets are associated with a poor prognosis. Further analysis showed that a high level of CD41+/CD62P+ platelets was significantly correlated with microvascular invasion (P = 0.002), advanced 8th edition AJCC stage (P < 0.001), and a high CA19-9 level (P = 0.027) and independently predicted a poor prognosis for resectable I/II PDAC. Furthermore, we found significantly higher Panx1 expression in CD41+/CD62P+ platelets than in CD41+/CD62P- platelets in PDAC patients. Mechanistically, Panx1 was able to enhance IL-1β secretion in CD41+/CD62P+ platelets by phosphorylating p38 MAPK and consequently promoted the invasion and metastasis of PDAC cells. Finally, we synthesized a novel compound named PC63435 by the ligation of carbenoxolone (a Panx1 inhibitor) and PSGL-1 (a CD62P ligand). PC63435 specifically bound to CD41+/CD62P+ platelets, then blocked the Panx1/IL-1β pathway and reduced the proportion of CD41+/CD62P+ platelets, which suppressed PDAC tumor invasion and metastasis in vivo. These results demonstrated that the Panx1/IL-1β axis in CD41+/CD62P+ platelets enhanced PDAC cell malignancy and that this axis may be a promising target for PDAC therapy.

Correlation between Macrophage Polarization and PD-L1-Related Tumor Microenvironmental Alteration and Metastasis in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a poor prognosis; nearly 80% patients have regional or distant metastasis when diagnosed. Tumor microenvironment (TME) alteration and epithelial-to-mesenchymal transition (EMT) have been reported to play a key role in cancer metastasis. However, the correlation between TME and EMT was poorly studied in PDAC. This study aims to explore the correlation between EMT markers and TME alteration, mainly including macrophage polarization and PD-L1 expression change, in primary and metastatic PDAC tissues by immunohistochemistry. The results indicated that macrophage polarization was found in metastases with the number of M1 macrophages (CD86+) decreased and M2 (CD163+) increased, though PD-L1 expression did not have a significant alteration. Compared to primary tumors, E-cadherin was significantly lower, while snail was higher, while no difference was found with N-cadherin and ZEB1. Correlation analysis indicated that snail, but not ZEB1, E-cadherin, or N-cadherin, was highly correlated with macrophage polarization. To conclude, the number of CD86+ M1 macrophages was increased while CD163+ M2 macrophages decreased in metastases, with no significant alteration of PD-L1 expression compared to primary tumors. EMT markers-Snail and E-cadherin-but not ZEB1 or N-cadherin, were found to be higher/lower in metastases, which mean that EMT played an important role in PDAC metastasis. Further analysis indicated that snail was highly correlated with M1 to M2 macrophage polarization, which prompted that EMT may be one reason for macrophage polarization induced TME alteration in PDAC metastasis.

Immune response and drug therapy based on ac4C-modified gene in pancreatic cancer typing.

N-4 cytidine acetylation (ac4C) is an epitranscriptome modification catalyzed by N-acetyltransferase 10 (NAT10) and is essential for cellular mRNA stability, rRNA biosynthesis, cell proliferation, and epithelial-mesenchymal transition (EMT). Numerous studies have confirmed the inextricable link between NAT10 and the clinical characteristics of malignancies. It is unclear, however, how NAT10 might affect pancreatic ductal adenocarcinoma. We downloaded pancreatic ductal adenocarcinoma patients from the TCGA database. We obtained the corresponding clinical data for data analysis, model construction, differential gene expression analysis, and the GEO database for external validation. We screened the published papers for NAT10-mediated ac4C modifications in 2156 genes. We confirmed that the expression levels and genomic mutation rates of NAT10 differed significantly between cancer and normal tissues. Additionally, we constructed a NAT10 prognostic model and examined immune infiltration and altered biological pathways across the models. The NAT10 isoforms identified in this study can effectively predict clinical outcomes in pancreatic ductal adenocarcinoma. Furthermore, our study showed that elevated levels of NAT10 expression correlated with gemcitabine resistance, that aberrant NAT10 expression may promote the angiogenic capacity of pancreatic ductal adenocarcinoma through activation of the TGF-β pathway, which in turn promotes distal metastasis of pancreatic ductal adenocarcinoma, and that NAT10 knockdown significantly inhibited the migration and clonogenic capacity of pancreatic ductal adenocarcinoma cells. In conclusion, we proposed a predictive model based on NAT10 expression levels, a non-invasive predictive approach for genomic profiling, which showed satisfactory and effective performance in predicting patients' survival outcomes and treatment response. Medicine and electronics will be combined in more interdisciplinary areas in the future.

KIF2C Facilitates Tumor Growth and Metastasis in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer with a poor prognosis. For PDAC, an increase in the survival time of patients and a reduction mortality have not yet successfully been achieved. In many research works, Kinesin family member 2C (KIF2C) is highly expressed in several tumors. Nevertheless, the role of KIF2C in pancreatic cancer is unknown. In this study, we found that KIF2C expression is significantly upregulated in human PDAC tissues and cell lines such as ASPC-1 and MIA-PaCa2. Moreover, KIF2C upregulation is associated with a poor prognosis when combining the expression of KIF2C with clinical information. Through cell functional assays and the construction of animal models, we showed that KIF2C promotes PDAC cell proliferation, migration, invasion, and metastasis, both in vitro and in vivo. Finally, the results of sequencing showed that the overexpression of KIF2C causes a decrease in some proinflammatory factors and chemokines. The cell cycle detection indicated that the pancreatic cancer cells in the overexpressed group had abnormal proliferation in the G2 and S phases. These results revealed the potential of KIF2C as a therapeutic target for the treatment of PDAC.

Antagonism between Prdm16 and Smad4 specifies the trajectory and progression of pancreatic cancer.

The transcription factor Prdm16 functions as a potent suppressor of transforming growth factor-beta (TGF-β) signaling, whose inactivation is deemed essential to the progression of pancreatic ductal adenocarcinoma (PDAC). Using the KrasG12D-based mouse model of human PDAC, we surprisingly found that ablating Prdm16 did not block but instead accelerated PDAC formation and progression, suggesting that Prdm16 might function as a tumor suppressor in this malignancy. Subsequent genetic experiments showed that ablating Prdm16 along with Smad4 resulted in a shift from a well-differentiated and confined neoplasm to a highly aggressive and metastatic disease, which was associated with a striking deviation in the trajectory of the premalignant lesions. Mechanistically, we found that Smad4 interacted with and recruited Prdm16 to repress its own expression, therefore pinpointing a model in which Prdm16 functions downstream of Smad4 to constrain the PDAC malignant phenotype. Collectively, these findings unveil an unprecedented antagonistic interaction between the tumor suppressors Smad4 and Prdm16 that functions to restrict PDAC progression and metastasis.

Coadaptation fostered by the SLIT2-ROBO1 axis facilitates liver metastasis of pancreatic ductal adenocarcinoma

To explore the mechanism of coadaptation and the potential drivers of pancreatic ductal adenocarcinoma (PDAC) metastasis to the liver, we study key molecules involved in this process and their translational value. Premetastatic niche (PMN) and macrometastatic niche (MMN) formation in a mouse model is observed via CT combined with 3D organ reconstruction bioluminescence imaging, and then we screen slit guidance ligand 2 (SLIT2) and its receptor roundabout guidance receptor 1 (ROBO1) as important factors. After we confirm the expression and distribution of SLIT2 and ROBO1 in samples from PDAC patients and several mouse models, we discover that SLIT2-ROBO1-mediated coadaptation facilitated the implantation and outgrowth of PDAC disseminated tumour cells (DTCs) in the liver. We also demonstrate the dependence receptor (DR) characteristics of ROBO1 in a follow-up mechanistic study. A neutralizing antibody targeting ROBO1 significantly attenuate liver metastasis of PDAC by preventing the coadaptation effect. Thus, we demonstrate that coadaptation is supported by the DR characteristics in the PMN and MMN.

New thoughts and findings on invasion and metastasis of pancreatic ductal adenocarcinoma (PDAC) from comparative proteomics: multi-target therapy.

As one of the most aggressive malignant tumors, pancreatic ductal adenocarcinoma (PDAC) ranks as the fourth cancer-related mortality in the world. The extremely low survival rate is closely related to early invasion and distant metastasis. However, effective target therapy for weakening its malignant behavior remains limited. Over the past decades, many proteins correlating with invasion and metastasis of PDAC have been discovered using proteomics. The discovery of these proteins gives us a deeper understanding of the invasive and migratory processes of PDAC. This review is a systemic integration of these proteomics findings over the past 10 years. The discovered proteins were typically associated with the glycolytic process, hypoxic microenvironment, post-translationalmodification, extracellular matrix, exosomes, cancer stem cells, and immune escape. Some proteins were found to have multiple functions, and, cooperation between different proteins in the invasive and metastatic processes was found. This cooperation, and not just single protein function, may play a more significant role in the poor prognosis of PDAC. Therefore, multi-target therapy against these cooperative networks should be a primary choice in the future.

The anti-metastasis effect of low-dose carbon monoxide

: Metastasis is the primary cause of cancer-related deaths. Because of the anatomically diffused localizations in different organs, treating metastatic cancer with conventional surgery or radiotherapy is challenging. Systemic therapies, including chemotherapy, immunotherapy, and targeted therapy, are used for metastatic cancer treatment. However, resistance to chemotherapy often develops over time, and immunotherapy or targeted therapy is not available for every cancer type. Improved systemic therapies for metastatic cancer are urgently needed. Among all forms of cancer, pancreatic ductal adenocarcinoma (PDAC) is a lethal type due to the following characteristics: early distant metastasis, abundant desmoplastic stroma, insufficient therapeutics, and frequent chemoresistance. Carbon monoxide (CO) is produced endogenously in humans and has been established as an important, biologically active signaling molecule. Accumulating evidence suggests the therapeutic applications of safe, low-dose CO for various diseases. Recently, low-dose CO was shown to suppress metastasis of PDAC in an orthotopic mouse model of liver metastasis and a spontaneous PDAC metastasis mouse model after the removal of primary tumor xenograft tumors. In this mini-review, we discuss the findings and the potential development of CO-based systemic therapies for metastatic cancer. Specifically, many non-inhalation CO delivery modalities with easy control of dosages have been developed and can be further studied for their anti-metastatic properties.

NKG2A blocks the anti-metastatic functions of natural killer cells.

Pancreatic ductal adenocarcinoma (PDAC)-derived liver metastasis represents a major unmet medical need. Liu etal. show that circulating tumor cells (CTCs) from the hepatic portal vein (HPV), and not from primary or metastatic sites, are protected from natural killer (NK) cells through the NKG2A/HLA-E axis. Interfering with this pathway unleashes NK cells and prevents PDAC metastasis.

Analysis of Risk Factors for Distant Metastasis of Pancreatic Ductal Adenocarcinoma without Regional Lymph Node Metastasis and a Nomogram Prediction Model for Survival.

Negative regional lymph nodes do not indicate a lack of distant metastasis. A considerable number of patients with negative regional lymph node pancreatic cancer will skip the step of regional lymph node metastasis and directly develop distant metastasis. We retrospectively analyzed the clinicopathological characteristics of patients with negative regional lymph node pancreatic cancer and distant metastasis in the Surveillance, Epidemiology, and End Results database from 2010 to 2015. Multivariate logistic analysis and Cox analysis were used to determine the independent risk factors that promoted distant metastasis and the 1-, 2-, and 3-year cancer-specific survival in this subgroup. Sex, age, pathological grade, surgery, radiotherapy, race, tumor location, and tumor size were significantly correlated with distant metastasis (P < 0.05). Among these factors, pathological grade II and above, tumor site other than the pancreatic head, and tumor size >40 mm were independent risk factors for distant metastasis; age ≥60 years, tumor size ≤21 mm, surgery, and radiation were protective factors against distant metastasis. Age, pathological grade, surgery, chemotherapy, and metastasis site were identified as predictors of survival. Among them, age ≥40 years, pathological grade II and above, and multiple distant metastasis were considered independent risk factors for cancer-specific survival. Surgery and chemotherapy were considered protective factors for cancer-specific survival. The prediction performance of the nomogram was significantly better than that of the traditional American Joint Committee on Cancer tumor, node, metastasis staging system. We also established an online dynamic nomogram calculator, which can predict the survival rate of patients at different follow-up time points. Pathological grade, tumor location, and tumor size were independent risk factors for distant metastasis in pancreatic ductal adenocarcinoma with negative regional lymph nodes. Older age, smaller tumor size, surgery, and radiotherapy were protective factors against distant metastasis. A new nomogram that was constructed could effectively predict cancer-specific survival in pancreatic ductal adenocarcinoma with negative regional lymph nodes and distant metastasis. Furthermore, an online dynamic nomogram calculator was established.

Chemoresistance in pancreatic ductal adenocarcinoma: Overcoming resistance to therapy.

Pancreatic ductal adenocarcinoma (PDAC), a prominent cause of cancer deaths worldwide, is a highly aggressive cancer most frequently detected at an advanced stage that limits treatment options to systemic chemotherapy, which has provided only marginal positive clinical outcomes. More than 90% of patients with PDAC die within a year of being diagnosed. PDAC is increasing at a rate of 0.5-1.0% per year, and it is expected to be the second leading cause of cancer-related mortality by 2030. The resistance of tumor cells to chemotherapeutic drugs, which can be innate or acquired, is the primary factor contributing to the ineffectiveness of cancer treatments. Although many PDAC patients initially responds to standard of care (SOC) drugs they soon develop resistance caused partly by the substantial cellular heterogeneity seen in PDAC tissue and the tumor microenvironment (TME), which are considered key factors contributing to resistance to therapy. A deeper understanding of molecular mechanisms involved in PDAC progression and metastasis development, and the interplay of the TME in all these processes is essential to better comprehend the etiology and pathobiology of chemoresistance observed in PDAC. Recent research has recognized new therapeutic targets ushering in the development of innovative combinatorial therapies as well as enhancing our comprehension of several different cell death pathways. These approaches facilitate the lowering of the therapeutic threshold; however, the possibility of subsequent resistance development still remains a key issue and concern. Discoveries, that can target PDAC resistance, either alone or in combination, have the potential to serve as the foundation for future treatments that are effective without posing undue health risks. In this chapter, we discuss potential causes of PDAC chemoresistance and approaches for combating chemoresistance by targeting different pathways and different cellular functions associated with and mediating resistance.

Surgery accelerates metastatic recurrence of PDAC: A novel, surgical, immune-competent mouse model

Background: Pancreatic ductal adenocarcinoma (PDAc) remains a resistant malignancy with dismal outcomes. Even with systemic treatment and surgical resection, 20-30% of patients will experience a metastatic recurrence within six months of surgery. This “rapid recurrence” (rrPDAc) is devastating and poorly understood and contributes to the nihilism surrounding pancreatic cancer. Etiologies of these metastatic lesions include occult synchronous metastases, as well as disseminated metachronous lesions, both of which we hypothesize may be affected by systemic and microenvironmental changes that occur due to surgical intervention. Unfortunately, identifying micrometastatic disease in humans before and after surgery is prohibitive, therefore we developed a preclinical system of PDAc metastasis accelerated by surgery. Metastatic models in PDAc are fraught with heavy utilization of intrasplenic or intraportal injections for seeding. They also frequently rely on immune-deficient murine hosts as well as tumor cell lines derived from metastatic lesions. Here, we describe accelerated induction of metastasis by surgery in an immune competent host.

PYGL-mediated glucose metabolism reprogramming promotes EMT phenotype and metastasis of pancreatic cancer.

Epithelial-mesenchymal transition (EMT) is closely associated with tumor invasion and metastasis. However, key regulators of EMT in pancreatic ductal adenocarcinoma (PDAC) need to be further studied. Bioinformatics analyses of pancreatic cancer public datasets showed that glycogen phosphorylase L (PYGL) expression is elevated in quasimesenchymal PDAC (QM-PDAC) and positively associated with EMT. In vitro cellular experiments further confirm PYGL as a crucial EMT regulator in PDAC cells. Functionally, PYGL overexpression promotes cell migration and invasion in vitro and facilitates liver metastasis in vivo, while PYGL knockdown has opposite effects. Mechanically, hypoxia induces PYGL expression in a hypoxia inducible factor 1α (HIF1α)-dependent manner and promotes glycogen accumulation. Elevated PYGL mobilizes accumulated glycogen to fuel glycolysis via its activity as a glycogen phosphorylase, thus inducing the EMT process, which could be suppressed by the glycolysis inhibitor 2-deoxy-D-glucose (2-DG). Clinically, PYGL expression is upregulated in PDAC and correlates with its malignant features and poor prognosis. Collectively, the data from our study reveal that the hypoxia/PYGL/glycolysis-induced EMT promotes PDAC metastasis, which establishes the rational for targeting hypoxia/PYGL/glycolysis/EMT signaling pathway against PDAC.

CD73, a Promising Therapeutic Target of Diclofenac, Promotes Metastasis of Pancreatic Cancer through a Nucleotidase Independent Mechanism

CD73, a cell surface-bound nucleotidase, facilitates extracellular adenosine formation by hydrolyzing 5'-AMP to adenosine. Several studies have shown that CD73 plays an essential role in immune escape, cell proliferation and tumor angiogenesis, making it an attractive target for cancer therapies. However, there are limited clinical benefits associated with the mainstream enzymatic inhibitors of CD73, suggesting that the mechanism underlying the role of CD73 in tumor progression is more complex than anticipated, and further investigation is necessary. In this study, CD73 is found to overexpress in the cytoplasm of pancreatic ductal adenocarcinoma (PDAC) cells and promotes metastasis in a nucleotidase-independent manner, which cannot be restrained by the CD73 monoclonal antibodies or small-molecule enzymatic inhibitors. Furthermore, CD73 promotes the metastasis of PDAC by binding to the E3 ligase TRIM21, competing with the Snail for its binding site. Additionally, a CD73 transcriptional inhibitor, diclofenac, a non-steroidal anti-inflammatory drug, is more effective than the CD73 blocking antibody for the treatment of PDAC metastasis. Diclofenac also enhances the therapeutic efficacy of gemcitabine in the spontaneous KPC (LSL-KrasG12D/+ , LSL-Trp53R172H/+ , and Pdx-1-Cre) pancreatic cancer model. Therefore, diclofenac may be an effective anti-CD73 therapy, when used alone or in combination with gemcitabine-based chemotherapy regimen, for metastatic PDAC.

Increased expression of miR-194-5p through the circPVRL3/miR-194-5p/SOCS2 axis promotes proliferation and metastasis in pancreatic ductal adenocarcinoma by activating the PI3K/AKT signaling pathway

BackgroundMicroRNAs (miRNAs), as an indispensable type of non-coding RNA (ncRNA), participate in diverse biological processes. However, the specific regulatory mechanism of certain miRNAs in pancreatic ductal adenocarcinoma (PDAC) remains unclear.MethodsThe expression of miR-194-5p in PDAC tissue microarray and cell lines were detected by RNA-scope and real-time quantitative PCR (RT-qPCR). The function of proliferation and migration carried by miR-194-5p in vitro and vivo was observed by several functional experiments. Informatics methods and RNA sequencing data were applied to explore the target of miR-194-5p and the upstream circular RNA (circRNA) of miR-194-5p. RNA-binding protein immunoprecipitation (RIP) assay and dual-luciferase reporter assay confirmed the relationships between miR-194-5p and SOCS2 or miR-194-5p and circPVRL3. The proliferation and migration abilities of SOCS2 and circPVRL3 were accessed by rescue experiments.ResultsIn this study, we aimed to clarify the molecular mechanisms of miR-194-5p, which has critical roles during PDAC progression. We found that the expression of miR-194-5p was significantly upregulated in PDAC tissue compared to tumor-adjacent tissue and was highly related to age and nerve invasion according to RNAscope and RT‒qPCR. Overexpression of miR-194-5p accelerated the cell cycle and enhanced the proliferation and migration processes according to several functional experiments in vitro and in vivo. Specifically, circPVRL3, miR-194-5p, and SOCS2 were confirmed to work as competing endogenous RNAs (ceRNAs) according to informatics methods, RIP, and dual-luciferase reporter assays. Additionally, the rescue experiments confirmed the relationship among miR-194-5p, circPVRL3, and SOCS2 mRNA. Finally, the circPVRL3/miR-194-5p/SOCS2 axis activates the PI3K/AKT signaling pathway to regulate the proliferation and metastasis of PDAC.ConclusionOur findings indicated that an increase of miR-194-5p caused by circPVRL3 downregulation stimulates the PI3K/AKT signaling pathway to promote PDAC progression via the circPVRL3/miR-194-5p/SOCS2 axis, which suggests that the circPVRL3/miR-194-5p/SOCS2 axis may be a potential therapeutic target for PDAC patients.

Metastatic phenotype and immunosuppressive tumour microenvironment in pancreatic ductal adenocarcinoma: Key role of the urokinase plasminogen activator (PLAU).

Previous studies have revealed the role of dysregulated urokinase plasminogen activator (encoded by PLAU) expression and activity in several pathways associated with cancer progression. However, systematic investigation into the association of PLAU expression with factors that modulate PDAC (pancreatic ductal adenocarcinoma) progression is lacking, such as those affecting stromal (pancreatic stellate cell, PSC)-cancer cell interactions, tumour immunity, PDAC subtypes and clinical outcomes from potential PLAU inhibition. This study used an integrated bioinformatics approach to identify prognostic markers correlated with PLAU expression using different transcriptomics, proteomics, and clinical data sets. We then determined the association of dysregulated PLAU and correlated signatures with oncogenic pathways, metastatic phenotypes, stroma, immunosuppressive tumour microenvironment (TME) and clinical outcome. Finally, using an in vivo orthotopic model of pancreatic cancer, we confirmed the predicted effect of inhibiting PLAU on tumour growth and metastasis. Our analyses revealed that PLAU upregulation is not only associated with numerous other prognostic markers but also associated with the activation of various oncogenic signalling pathways, aggressive phenotypes relevant to PDAC growth and metastasis, such as proliferation, epithelial-mesenchymal transition (EMT), stemness, hypoxia, extracellular cell matrix (ECM) degradation, upregulation of stromal signatures, and immune suppression in the tumour microenvironment (TME). Moreover, the upregulation of PLAU was directly connected with signalling pathways known to mediate PSC-cancer cell interactions. Furthermore, PLAU upregulation was associated with the aggressive basal/squamous phenotype of PDAC and significantly reduced overall survival, indicating that this subset of patients may benefit from therapeutic interventions to inhibit PLAU activity. Our studies with a clinically relevant orthotopic pancreatic model showed that even short-term PLAU inhibition is sufficient to significantly halt tumour growth and, importantly, eliminate visible metastasis. Elevated PLAU correlates with increased aggressive phenotypes, stromal score, and immune suppression in PDAC. PLAU upregulation is also closely associated with the basal subtype type of PDAC; patients with this subtype are at high risk of mortality from the disease and may benefit from therapeutic targeting of PLAU.