Invasive Pancreatic Ductal Adenocarcinoma Research Articles

Hematopoietic progenitor kinase 1 inhibits the development and progression of pancreatic intraepithelial neoplasia.

Ras plays an essential role in the development of acinar-to-ductal metaplasia (ADM) and pancreatic ductal adenocarcinoma (PDAC). However, mutant Kras is an inefficient driver for PDAC development. The mechanisms of the switching from low Ras activity to high Ras activity that are required for development and progression of pancreatic intraepithelial neoplasias (PanINs) are unclear. In this study, we found that hematopoietic progenitor kinase 1 (HPK1) was upregulated during pancreatic injury and ADM. HPK1 interacted with the SH3 domain and phosphorylated Ras GTPase-activating protein (RasGAP) and upregulated RasGAP activity. Using transgenic mouse models of HPK1 or M46, a kinase-dead mutant of HPK1, we showed that HPK1 inhibited Ras activity and its downstream signaling and regulated acinar cell plasticity. M46 promoted the development of ADM and PanINs. Expression of M46 in KrasG12D Bac mice promoted the infiltration of myeloid-derived suppressor cells and macrophages, inhibited the infiltration of T cells, and accelerated the progression of PanINs to invasive and metastatic PDAC, while HPK1 attenuated mutant Kras-driven PanIN progression. Our results showed that HPK1 plays an important role in ADM and the progression of PanINs by regulating Ras signaling. Loss of HPK1 kinase activity promotes an immunosuppressive tumor microenvironment and accelerates the progression of PanINs to PDAC.

Quantification of perineural invasion in pancreatic ductal adenocarcinoma: proposal of a severity score system.

Perineural invasion (PNI) is a common feature in pancreatic ductal adenocarcinoma (PDAC) and correlates with an aggressive tumor behavior already at early stages of disease. PNI is currently considered as a "present vs. absent" feature, and a severity score system has not yet been established. The aim of the present study was thus to develop and validate a score system for PNI and to correlate it with other prognostic features. In this monocentric retrospective study, 356 consecutive PDAC patients (61.8% upfront surgery patients, 38.2% received neoadjuvant therapy) were analyzed. PNI was scored as follows: 0: absent; 1: the presence of neoplasia along nerves < 3mm in caliber; and 2: neoplastic infiltration of nerve fibers ≥ 3mm and/or massive perineural infiltration and/or the presence of necrosis of the infiltrated nerve bundle. For every PNI grade, the correlation with other pathological features, disease-free survival (DFS), and disease-specific survival (DSS) were analyzed. Uni- and multivariate analysis for DFS and DSS were also performed. PNI was found in 72.5% of the patients. Relevant trends between PNI score and tumor differentiation grade, lymph node metastases, vascular invasion, and surgical margins status were found. The latter was the only parameter statistically correlated with the proposed score. The agreement between pathologists was substantial (Cohen's K 0.61). PNI severity score significantly correlated also with decreased DFS and DSS at univariate analysis (p < 0.001). At multivariate analysis, only the presence of lymph node metastases was an independent predictor of DFS (HR 2.235 p < 0.001). Lymph node metastases (HR 2.902, p < 0.001) and tumor differentiation grade (HR 1.677, p = 0.002) were independent predictors of DSS. Our newly developed PNI score correlates with other features of PDAC aggressiveness and proved to have a prognostic role though less robust than lymph nodes metastases and tumor differentiation grade. A prospective validation is needed.

Preoperative prediction of microvascular invasion and perineural invasion in pancreatic ductal adenocarcinoma with 18F-FDG PET/CT radiomics analysis

To develop and validate a predictive model based on 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) radiomics features and clinicopathological parameters to preoperatively identify microvascular invasion (MVI) and perineural invasion (PNI), which are important predictors of poor prognosis in patients with pancreatic ductal adenocarcinoma (PDAC). Preoperative 18F-FDG PET/CT images and clinicopathological parameters of 170 patients in PDAC were collected retrospectively. The whole tumour and its peritumoural variants (tumour dilated with 3, 5, and 10 mm pixels) were applied to add tumour periphery information. A feature-selection algorithm was employed to mine mono-modality and fused feature subsets, then conducted binary classification using gradient boosted decision trees. For MVI prediction, the model performed best on a fused subset of 18F-FDG PET/CT radiomics features and two clinicopathological parameters, with an area under the receiver operating characteristic curve (AUC) of 83.08%, accuracy of 78.82%, recall of 75.08%, precision of 75.5%, and F1-score of 74.59%. For PNI prediction, the model achieved best prediction results only on the subset of PET/CT radiomics features, with AUC of 94%, accuracy of 89.33%, recall of 90%, precision of 87.81%, and F1 score of 88.35%. In both models, 3 mm dilation on the tumour volume produced the best results. The radiomics predictors from preoperative 18F-FDG PET/CT imaging exhibited instructive predictive efficacy in the identification of MVI and PNI status preoperatively in PDAC. Peritumoural information was shown to assist in MVI and PNI predictions.

Gender-specific changes of the gut microbiome correlate with tumor development in murine models of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a dismal outcome. To improve understanding of sequential microbiome changes during PDAC development we analyzed mouse models of pancreatic carcinogenesis (KC mice recapitulating pre-invasive PanIN formation, as well as KPC mice recapitulating invasive PDAC) during early tumor development and subsequent tumor progression. Diversity and community composition were analyzed depending on genotype, age, and gender. Both mouse models demonstrated concordant abundance changes of several genera influenced by one or more of the investigated factors. Abundance was significantly impacted by gender, highlighting the need to further elucidate the impact of gender differences. The findings underline the importance of the microbiome in PDAC development and indicate that microbiological screening of patients at risk and targeting the microbiome in PDAC development may be feasible in future.

SUMO specific peptidase 3 halts pancreatic ductal adenocarcinoma metastasis via deSUMOylating DKC1

In the past few decades, advances in the outcomes of patients suffering from pancreatic ductal adenocarcinoma (PDAC) have lagged behind these gained in the treatment of many other malignancies. Although the pivotal role of the SUMO pathway in PDAC has been illustrated, the underlying molecule drivers have yet to be fully elucidated. In the present study, we identified SENP3 as a potential suppressor of PDAC progression through an in vivo metastatic model. Further studies revealed that SENP3 inhibited PDAC invasion in a SUMO system dependent fashion. Mechanistically, SENP3 interacted with DKC1 and, as such, catalyzed the deSUMOylation of DKC1, which accepted SUMO3 modifiers at three lysine residues. SENP3-mediated deSUMOylation caused DKC1 instability and disruption of the interaction between snoRNP proteins, which contributed to the impaired migration ability of PDAC. Indeed, overexpression of DKC1 abated the anti-metastasis effect of SENP3, and DKC1 was elevated in PDAC specimens and associated with a poor prognosis in PDAC patients. Collectively, our findings shed light on the essential role of SENP3/DKC1 axis in the progression of PDAC.

CircPTPRA promotes the progression of pancreatic ductal adenocarcinoma via the miR-140-5p/LMNB1 axis.

Growing evidences suggest that circular RNAs (circRNAs) are important factors in cancer progression. Nevertheless, the role of circRNAs in the progression of pancreatic ductal adenocarcinoma (PDAC) remains unclear. CircPTPRA was identified based on our previous circRNA array data analysis. Wound healing, transwell, and EdU assays were performed to investigate the effect of circPTPRA on the migration, invasion, and proliferation of PDAC cells in vitro. RNA pull-down, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP), and dual-luciferase reporter assays were conducted to verify the binding of circPTPRA with miR-140-5p. Subcutaneous xenograft model was constructed for in vivo experiment. CircPTPRA was significantly upregulated in PDAC tissues and cells compared to normal controls. Moreover, circPTPRA overexpression was positively correlated with lymph node invasion and worse prognosis in PDAC patients. In addition, overexpression of circPTPRA promoted PDAC migration, invasion, proliferation, and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Mechanistically, circPTPRA upregulates LaminB1 (LMNB1) expression by sponging miR-140-5p and ultimately promotes the progression of PDAC. This study revealed that circPTPRA plays an important role in the progression of PDAC by sponging miR-140-5p. It can be explored as a potential prognostic marker and therapeutic target for PDAC.

Protein Induced by Vitamin K Absence II: A Potential Biomarker to Differentiate Pancreatic Ductal Adenocarcinoma from Pancreatic Benign Lesions and Predict Vascular Invasion.

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant gastrointestinal tumor with a poor prognosis. Serum biomarker carbohydrate antigen 19-9 (CA19-9) was the only well-established biomarker for PDAC with inadequate efficacy. This present study aimed to determine the ability of PIVKA-II to discriminate PDAC from pancreatic benign lesions and predict vascular invasion preoperatively. Patients who underwent pancreatic surgery from 2017 to 2020 were enrolled. We examined the differential diagnostic ability of protein induced by vitamin K absence II (PIVKA-II), CA19-9, and their combination and 138 with PDAC evaluated the predictive value of PIVKA-II for vascular invasion in PDAC. A total of 138 patients with PDAC and 90 patients with pancreatic benign lesions who underwent pancreatic surgery from 2017 to 2020 were enrolled. The clinicopathological characteristics were recorded. There was a significant difference in levels of serum PIVKA-II between PDAC patients and patients with pancreatic benign lesions (p < 0.001). When the cut-off value was set to 28.9 mAU/mL according to the ROCs, the AUC, sensitivity, and specificity of PIVKA-II were 0.787, 68.1%, and 83.3%, respectively. The combined PIVKA-II and carbohydrate antigen 19-9 (CA19-9) enhanced the diagnostic accuracy, and the AUC, sensitivity, and specificity were 0.945, 87.7%, and 94.4%, respectively. PIVKA-II > 36.4 mAU/mL were independent predictive factors of vascular invasion in PDAC (p < 0.001). PIVKA-II was a potential diagnostic biomarker to differentiate PDAC from pancreatic benign lesions. PIVKA-II was complementary to CA19-9, and the combination enhanced the differential diagnostic performance. PIVKA-II > 36.4 mAU/mL was an independent predictive factor of vascular invasion in PDAC.

Perineural Invasion of Pancreatic Ductal Adenocarcinoma is Associated with Early Recurrence after Neoadjuvant Therapy Followed by Resection.

Neoadjuvant therapy (NAT) is increasingly utilized in the treatment of pancreatic ductal adenocarcinoma (PDAC). However, there are limited data on risk factors and patterns of recurrence after surgical resection. This study aimed to analyze timing and recurrence patterns of PDAC after NAT followed by curative resection. The medical charts of patients with PDAC treated with NAT followed by curative-intent surgical resection at a single health system from January 1, 2012 to January 1, 2020 were retrospectively reviewed. Early recurrence was defined as recurrence within 12months of surgical resection. 91 patients were included and median follow up was 20.1months. Recurrence occurred in 50 (55%) patients, with median recurrence free survival (RFS) of 11.9months. Overall, 18 (36%) patients had local and 32 (64%) had distant recurrences. Median RFS and overall survival (OS) between local and distant recurrence were similar. Perineural invasion (PNI) and the presence of a T2 + tumor was significantly higher in recurrence group than in no recurrence group. PNI was a significant risk factor for early recurrence. After NAT and surgical resection of PDAC, disease recurrence was common, with distant metastasis being the most common. PNI was significantly higher in the recurrence group.

Determination of arterial invasion in pancreatic ductal adenocarcinoma: what is the best diagnostic criterion on CT?

To investigate the diagnostic performance and interobserver variability in the determination of arterial invasion in pancreatic ductal adenocarcinoma (PDAC) and determine the best CT imaging criterion. We retrospectively evaluated 128 patients with PDAC (73 men and 55 women) who underwent preoperative contrast-enhanced CT. Five board-certified radiologists (expert) and four fellows (non-expert]) independently assessed the arterial invasion (celiac, superior mesenteric, splenic, and common hepatic arteries) using a 6-point score: 1, no tumor contact; 2, hazy attenuation ≤ 180°; 3, hazy attenuation > 180°; 4, solid soft tissue contact ≤ 180°; 5, solid soft tissue contact > 180°; and 6, contour irregularity. ROC analysis was performed to evaluate the diagnostic performance and determine the best diagnostic criterion for arterial invasion, with pathological or surgical findings as references. Interobserver variability was assessed using Fleiss's ĸ statistics. Among the 128 patients, 35.2% (n = 45/128) received neoadjuvant treatment (NTx). Solid soft tissue contact ≤ 180° was the best diagnostic criterion for arterial invasion as defined by the Youden Index both in patients who did and did not receive NTx (sensitivity, 100% vs. 100%; specificity, 90% vs. 93%; and AUC, 0.96 vs. 0.98, respectively). Interobserver variability among the non-expert was not inferior to that among the expert (ĸ = 0.61 vs 0.61; p = .39 and ĸ = 0.59 vs 0.51; p < .001 in patients treated with and without NTx, respectively). Solid soft tissue contact ≤ 180° was the best diagnostic criterion for the determination of arterial invasion in PDAC. Considerable interobserver variability was seen among the radiologists. • Solid soft tissue contact ≤ 180° was the best diagnostic criterion for the determination of arterial invasionin pancreatic ductal adenocarcinoma. • Interobserver agreement among non-expert radiologists was almost comparable to that among expert radiologists.

Integrated analysis of Dendrobium nobile extract Dendrobin A against pancreatic ductal adenocarcinoma based on network pharmacology, bioinformatics, and validation experiments.

Background: Dendrobium nobile (D. nobile), a traditional Chinese medicine, has received attention as an anti-tumor drug, but its mechanism is still unclear. In this study, we applied network pharmacology, bioinformatics, and in vitro experiments to explore the effect and mechanism of Dendrobin A, the active ingredient of D. nobile, against pancreatic ductal adenocarcinoma (PDAC). Methods: The databases of SwissTargetPrediction and PharmMapper were used to obtain the potential targets of Dendrobin A, and the differentially expressed genes (DEGs) between PDAC and normal pancreatic tissues were obtained from The Cancer Genome Atlas and Genotype-Tissue Expression databases. The protein-protein interaction (PPI) network for Dendrobin A anti-PDAC targets was constructed based on the STRING database. Molecular docking was used to assess Dendrobin A anti-PDAC targets. PLAU, one of the key targets of Dendrobin A anti-PDAC, was immunohistochemically stained in clinical tissue arrays. Finally, in vitro experiments were used to validate the effects of Dendrobin A on PLAU expression and the proliferation, apoptosis, cell cycle, migration, and invasion of PDAC cells. Results: A total of 90 genes for Dendrobin A anti-PDAC were screened, and a PPI network for Dendrobin A anti-PDAC targets was constructed. Notably, a scale-free module with 19 genes in the PPI indicated that the PPI is highly credible. Among these 19 genes, PLAU was positively correlated with the cachexia status while negatively correlated with the overall survival of PDAC patients. Through molecular docking, Dendrobin A was found to bind to PLAU, and the Dendrobin A treatment led to an attenuated PLAU expression in PDAC cells. Based on clinical tissue arrays, PLAU protein was highly expressed in PDAC cells compared to normal controls, and PLAU protein levels were associated with the differentiation and lymph node metastatic status of PDAC. In vitro experiments further showed that Dendrobin A treatment significantly inhibited the proliferation, migration, and invasion, inducing apoptosis and arresting the cell cycle of PDAC cells at the G2/M phase. Conclusion: Dendrobin A, a representative active ingredient of D. nobile, can effectively fight against PDAC by targeting PLAU. Our results provide the foundation for future PDAC treatment based on D. nobile.

Comparison of Invasive Pancreatic Ductal Adenocarcinoma versus Intraductal Papillary Mucinous Neoplasm: A National Cancer Database Analysis

Current evidence on overall survival (OS) between invasive pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary mucinous neoplasm (IPMN) is limited to single-center reports. We aimed to compare the characteristics, management, and OS of invasive PDAC vs. IPMN using a national United States (US) database. Invasive PDAC or IPMN adult (≥18 years) patients were identified in the National Cancer Database (2004-2016). OS was assessed with the Kaplan-Meier method and the stratified log-rank test. We included 101,190 patients (100,834 PDAC, 356 IPMN). A higher proportion of PDAC vs. IPMN patients had clinical N1 (36.8% vs. 15.7%, p < 0.001) and M1 disease (41.2% vs. 5.9%, p < 0.001). A lower proportion of PDAC patients underwent surgery (25.5% vs. 80.3%, p < 0.001), but a higher proportion received chemotherapy (65.4% vs. 46.1%, p < 0.001) or radiation (25.3% vs. 20.5%, p = 0.04). A higher proportion of surgical patients with PDAC vs. IPMN underwent margin-positive resection (23.0% vs. 14.0%, p = 0.001). The median OS for PDAC vs. IPMN was 8.3 vs. 33.4 months. In the stratified analysis for N0M0 disease, the median OS for PDAC vs. IPMN was 12.8 vs. 43.3 months, for N1M0, it was 11.5 vs. 17.0 months, while for M1, it was 4.0 vs. 7.0 months. In both diagnoses, surgery yielded improved OS, while stratified analysis in the surgical cohort demonstrated similar findings. Invasive PDAC is more aggressive than invasive IPMN, yet in the case of metastasis, OS is equally poor. Excellent long-term OS is achievable with surgical resection in highly selected cases, and efforts should focus on facilitating surgical treatment.

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.

SALL4-related gene signature defines a specific stromal subset of pancreatic ductal adenocarcinoma with poor prognostic features.

Pancreatic ductal adenocarcinoma (PDAC) is marked by molecular heterogeneity and poor prognosis. Among the stemness-related transcription factors, Spalt-like Transcription Factor 4 (SALL4) is correlated with unfavorable outcomes; however, its roles in PDAC remain unclear. SALL4high expression defines a PDAC subpopulation characterized by a shortened patient survival. Although SALL4 expression was mostly evaluated in tumor cells, our findings identify this embryonic transcription factor as a new biomarker in PDAC-derived stroma. Gene expression analysis reveals that the SALL4high PDAC subset is enriched in cancer stem cell properties and stromal enrichment pathways; notably, an interaction with cancer-associated fibroblasts (CAF) activated by TGF-β. A particular oncogenic network was unraveled where Netrin-1 and TGF-β1 collaborate to induce SALL4 expression in CAF and drive their cancer-stemness-promoting functions. A 7-gene stromal signature related to SALL4high PDAC samples was highlighted and validated by immunochemistry for prognosis and clinical application. This SALL4-related stroma discriminated pancreatic preinvasive from invasive lesions and was enriched in short-term survivors. Our results show that SALL4 transcriptional activity controls a molecular network defined by a specific stromal signature that characterizes PDAC invasiveness and worse clinical outcomes.

Involvement of angiogenesis in cancer-associated acinar-to-ductal metaplasia lesion of pancreatic cancer invasive front.

This study aimed to demonstrate the involvement of angiogenesis in cancer-associated acinar-to-ductal metaplasia (CA-ADM) lesion of invasive front pancreatic ductal adenocarcinoma (PDAC) and investigate the possible mechanism. Tissue samples from 128 patients with PDAC and 36 LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre mice were analyzed. Immunohistochemical assay was performed using HE, anti-CK19 and anti-amylase to confirm the presence of CA-ADM lesions, using anti-CD34 and anti-CD31 to measure microvessel density (MVD), and using anti-CD68, anti-CD163, anti-iNOS, or anti-MMP9 to evaluate the immune microenvironment. We performed multiplex immunohistochemical assay to detect the co-expression of MMP9 and CD68 on macrophage. We examined clinical outcomes and other clinicopathological factors to determine the significance of high-level MVD of CA-ADM on survival and liver metastasis. We performed tube formation assay to evaluate the effect of macrophage on angiogenic capacity in vitro. Angiogenesis was significantly abundant in CA-ADM lesions compared with that in PDAC lesions in human and mouse tissues. High-level MVD in CA-ADM lesions was an independent predictor of poor prognosis (P = 0.0047) and the recurrence of liver metastasis (P = 0.0027). More CD68-positive and CD163-positive macrophages were detected in CA-ADM lesions than in PDAC. The percentage of CD68-positive macrophages was positively correlated with MVD in CA-ADM lesions. Multiplex-immunostaining revealed that MMP9 was expressed in CD68-positive macrophages of CA-ADM lesions. In CA-ADM lesions, the percentage of macrophages was positively correlated with MMP9 expression, which positively correlated with microvessel density. CA-ADM related angiogenesis is a promising predictive marker for poor prognosis of PDAC and may provide an attractive therapeutic target for PDAC.

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.

Epithelial and stromal co-evolution and complicity in pancreatic cancer.

Pancreatic ductal adenocarcinomas are distinguished by their robust desmoplasia, or fibroinflammatory response. Dominated by non-malignant cells, the mutated epithelium must therefore combat, cooperate with or co-opt the surrounding cells and signalling processes in its microenvironment. It is proposed that an invasive pancreatic ductal adenocarcinoma represents the coordinated evolution of malignant and non-malignant cells and mechanisms that subvert and repurpose normal tissue composition, architecture and physiology to foster tumorigenesis. The complex kinetics and stepwise development of pancreatic cancer suggests that it is governed by a discrete set of organizing rules and principles, and repeated attempts to target specific components within the microenvironment reveal self-regulating mechanisms of resistance. The histopathological and genetic progression models of the transforming ductal epithelium must therefore be considered together with a programme of stromal progression to create a comprehensive picture of pancreatic cancer evolution. Understanding the underlying organizational logic of the tumour to anticipate and pre-empt the almost inevitable compensatory mechanisms will be essential to eradicate the disease.

Perineural Invasion in Pancreatic Ductal Adenocarcinoma: From Molecules towards Drugs of Clinical Relevance

Pancreatic ductal adenocarcinoma is one of the most threatening solid malignancies. Molecular and cellular mediators that activate paracrine signalling also regulate the dynamic interaction between pancreatic cancer cells and nerves. This reciprocal interface leads to perineural invasion (PNI), defined as the ability of cancer cells to invade nerves, similar to vascular and lymphatic metastatic cascade. Targeting PNI in pancreatic cancer might help ameliorate prognosis and pain relief. In this review, the modern knowledge of PNI in pancreatic cancer has been analysed and critically presented. We focused on molecular pathways promoting cancer progression, with particular emphasis on neuropathic pain generation, and we reviewed the current knowledge of pharmacological inhibitors of the PNI axis. PNI represents a common hallmark of PDAC and correlates with recurrence, poor prognosis and pain in pancreatic cancer patients. The interaction among pancreatic cancer cells, immune cells and nerves is biologically relevant in each stage of the disease and stimulates great interest, but the real impact of the administration of novel agents in clinical practice is limited. It is still early days for PNI-targeted treatments, and further advanced studies are needed to understand whether they could be effective tools in the clinical setting.

Abstract B053: Targeting SMURF1 with low-dose proteasome inhibitors in pancreatic cancer organoids

Abstract Global initiatives focused on whole genome and transcriptome analysis (WGTA) of metastatic pancreatic ductal adenocarcinoma (PDAC) tumor cohorts are driving progress in understanding the clinical impact of PDAC heterogeneity. This knowledge is key to continue the discovery of subsets of patients who could benefit from biomarker-informed targeted therapy and expand the currently limited PDAC treatment options. To identify clinically actionable subtypes in metastatic PDAC (mPDAC), our team analyzes prospectively collected WGTA data from patients enrolled in the PanGen trial (NCT02869802), in parallel with analysis of a set of patient-derived organoids (PDOs). In a cohort of 69 sequenced tumors, four cases (5.8%) had an amplification of chromosome 7q22, which included copy gains of transcriptional co-factor TRRAP, drug metabolizing cytochrome P450 genes CYP3A4 and CYP3A5, and SMURF1. SMURF1 is a ubiquitin-protein ligase that regulates TGFβ receptor signaling, in part via its interaction with SMAD7, and has been implicated in the epithelial-to-mesenchymal program and tumor invasiveness in PDAC. The proteasome inhibitor (PI) bortezomib has been shown to attenuate SMURF1 levels. We investigated whether SMURF1 signaling axis is associated with sensitivity to PIs in mPDAC, by analyzing the cytotoxic effects of the PIs bortezomib, carfilzomib and ixazomib in PDOs. Eight PDOs were treated with PIs at concentrations between 0.1pM-1mM. The presence of live and dead cells was quantified using the IN Cell Analyzer, and cell toxicity was analyzed using GRtoxic metrics (grcalculator.org). The PIs bind catalytic subunits of the 26S proteasome, primarily proteasome subunit beta-5, encoded by PSMB5. The cytotoxic activity of all three PIs negatively correlated with tumor biopsy PSMB5 expression (p&amp;lt;0.05), suggesting that PDOs established from tumors with low expression of PSMB5 are more sensitive to PI-induced cell death. There was a positive correlation between ixazomib cytotoxicity and SMURF1 expression (p&amp;lt;0.05). PanGen patients with high (&amp;gt;75th percentile) tumor SMURF1 expression showed shorter overall survival (OS) compared to the rest of the cohort (median OS 9 vs. 14 months, respectively; p=0.004). Immunohistochemistry analysis of a tumor tissue microarray comprising 175 resected PDAC cases detected an association of concomitant low SMURF1 and high SMAD7 protein levels with adjuvant therapy response (median OS: 40 vs. 12 months with no adjuvant treatment, p=0.002), suggesting that attenuation of SMURF1 in the presence of SMAD7 may improve chemotherapy response in early disease stages. In summary, we present data indicating increased sensitivity to PIs in a subset of tumors with low PSMB5 and high SMURF1 expression, and highlight the translational utility of the investigation of genomic and clinically annotated pre-clinical models in PDAC predictive biomarker discovery. Citation Format: Andrew Metcalfe, Joanna M. Karasinska, James T. Topham, Steve E. Kalloger, Hassan Ali, Dawn Ashforth, Marco A. Marra, Janessa Laskin, Patricia A. Tang, Rachel Goodwin, Oliver F. Bathe, Daniel J. Renouf, David F. Schaeffer. Targeting SMURF1 with low-dose proteasome inhibitors in pancreatic cancer organoids [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 B053.

CDCA8/SNAI2 Complex Activates CD44 to Promote Proliferation and Invasion of Pancreatic Ductal Adenocarcinoma.

(1) Background: Recently, cell division cycle associated 8 (CDCA8) was found to be overexpressed in pancreatic ductal adenocarcinoma (PDAC). Here, we aimed to explore the specific mechanism of action of CDCA8 in PDAC progression. (2) Methods: All human PDAC samples and clinical data were collected from Huashan Hospital, Fudan University. All experimental studies were carried out using many in vitro and in vivo assays, including lentiviral transfection, real-time quantitative polymerase chain reaction (qPCR), western blotting, co-immunoprecipitation (Co-IP), chromatin IP (ChIP)-qPCR, dual-luciferase reporter, and in vivo imaging assays. (3) Results: Clinical data analysis of human PDAC samples revealed that CDCA8 overexpression were positively and negatively associated with tumor grade (p = 0.007) and overall survival (p = 0.045), respectively. CDCA8 knockdown inhibited PDAC proliferation and invasion in in vitro and in vivo assays. CD44 was also up-regulated by CDCA8 during PDAC progression. CDCA8 could be combined with SNAI2 to form a CDCA8/SNAI2 complex to integrate with the CD44 promoter as indicated through ChIP-qPCR and dual-luciferase reporter assays. (4) Conclusion: We showed that CDCA8-CD44 axis plays a key role in the proliferation and invasion of PDAC, which provides a potential target for treatment.

Suppressive effect of YY1-mediated RGS22 regulation on the proliferation, migration and invasion of pancreatic ductal adenocarcinoma.

Regulator of G-protein signaling 22 (RGS22) is specifically expressed in the testis and in tumors of epithelial origin, but the expression and role of RGS22 in pancreatic cancer are unclear. In this study, 52 pairs of pancreatic ductal adenocarcinoma (PDAC) and adjacent non-neoplastic tissue samples with the corresponding clinical data were used to examine the expression of RGS22 and its relationship with PDAC prognosis. The findings showed that the expression of RGS22 was higher in the PDAC tissues than in the adjacent non-tumorous tissues and its expression was associated with the degree of blood vessel invasion. The in vitro experiments with PDAC cell lines and a normal control cell line showed that the proliferation, invasion, and metastasis of PDAC cells were suppressed by RGS22 overexpression and enhanced by RGS22 knockdown. The in vivo effect of RGS22 on PDAC xenografts was studied using subcutaneous implantation of tumor cells in BALB/cA-nu mice, and the results corroborated the in vitro findings. Analysis of the regulators of RGS22 showed that it was positively regulated by the transcription factor Yin Yang-1 (YY1). Thus, YY1-mediated RGS22 regulation suppressed the proliferation, migration, and invasion of PDAC.