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Background: Cancer-associated fibroblasts (CAFs) play pivotal roles in chemoresistance of pancreatic ductal adenocarcinoma (PDAC). However, the underlying mechanisms are poorly understood. Revealing the cross-talk network between tumor stroma and pancreatic cancer and developing effective strategies against oxaliplatin resistance are highly desired in the clinic. Methods: High-throughput sequence was used to screened the key circRNAs transmitted by extracellular vesicles (EVs) from CAFs to pancreatic cancer cells. The associations between EV-packaged circBIRC6 and chemotherapy responsiveness were validated in a cohort of 82 cases of advanced PDAC patients. Then, the effects of EV-packaged circBIRC6 on CAF-induced oxaliplatin resistance were investigated by flow cytometry, colony formation, viability of pancreatic cancer organoids in vitro and by xenograft models in vivo. RNA pulldown, RNA immunoprecipitation, and sites mutation assays were used to reveal the underlying mechanism. Results: We identified a circRNA, circBIRC6, is significantly upregulated in CAF-derived EVs and is positively associated with oxaliplatin-based chemoresistance. In vitro and in vivo functional assays showed that CAF-derived EV-packaged circBIRC6 enhance oxaliplatin resistance of pancreatic cancer cells and organoids via regulating the non-homologous end joining (NHEJ) dependent DNA repair. Mechanistically, circBIRC6 directly binds with XRCC4 and enhanced the interaction of XRCC4 with SUMO1 at the lysine 115 residue, which facilitated XRCC4 chromatin localization. XRCC4K115R mutation dramatically abrogated the EV-packaged circBIRC6 induced effect. Moreover, combination of antisense oligonucleotide inhibitors against circBIRC6 with Olaparib dramatically suppressed chemoresistance in patient-derived xenograft models. Conclusions: Our study revealed that EV-packaged circBIRC6 confer oxaliplatin resistance in PDAC by mediating SUMOylation of XRCC4, introducing a promising predictive and therapeutic target for PDAC on oxaliplatin resistance. [ABSTRACT FROM AUTHOR]

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by clusters of cancer cells surrounded by a dense desmoplastic stroma. However, little is known about stromal cell heterogeneity in the pancreatic tumor microenvironment. Methods: We conducted circRNA profiling in primary fibroblasts by high-throughput sequencing and detected circCUL2 levels in PDAC tissues by qRT–PCR. We subsequently investigated the effect of circCUL2 on inflammatory cancer-associated fibroblast (iCAF) activation, heterogeneity and protumor activity by ELISA, flow cytometry, colony formation and transwell assays in vitro and by xenograft models in vivo. The regulatory effect of circCUL2 on miR-203a-3p/MyD88/IL6 was examined by RNA pulldown, FISH, and luciferase reporter assays. Results: We identified that circCUL2 was specifically expressed in cancer-associated fibroblasts (CAFs) but not in cancer cells. Moreover, the enrichment of circCUL2 in tumor tissues was significantly correlated with the poor prognosis of PDAC patients. Upregulation of circCUL2 expression in normal fibroblasts (NFs) induced the iCAF phenotype, and then iCAFs promoted PDAC progression through IL6 secretion in vitro. Furthermore, circCUL2-transduced NFs promoted tumorigenesis and metastasis of PDAC cells in vivo, which was blocked by an anti-IL6 antibody. Mechanistically, circCUL2 functioned as a ceRNA and modulated the miR-203a-3p/MyD88/NF-κB/IL6 axis, thereby further activating the STAT3 signaling pathway in pancreatic cancer cells to induce PDAC progression. Conclusions: We showed that the circCUL2/miR-203a-5p/MyD88/NF-κB/IL6 axis contributes to the induction of iCAFs and established a distinct fibroblast niche for PDAC progression, which could help the development of strategies that selectively target tumor-promoting CAFs in PDAC. [ABSTRACT FROM AUTHOR]

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by clusters of cancer cells surrounded by a dense desmoplastic stroma. However, little is known about stromal cell heterogeneity in the pancreatic tumor microenvironment. Methods: We conducted circRNA profiling in primary fibroblasts by high-throughput sequencing and detected circCUL2 levels in PDAC tissues by qRT–PCR. We subsequently investigated the effect of circCUL2 on inflammatory cancer-associated fibroblast (iCAF) activation, heterogeneity and protumor activity by ELISA, flow cytometry, colony formation and transwell assays in vitro and by xenograft models in vivo. The regulatory effect of circCUL2 on miR-203a-3p/MyD88/IL6 was examined by RNA pulldown, FISH, and luciferase reporter assays. Results: We identified that circCUL2 was specifically expressed in cancer-associated fibroblasts (CAFs) but not in cancer cells. Moreover, the enrichment of circCUL2 in tumor tissues was significantly correlated with the poor prognosis of PDAC patients. Upregulation of circCUL2 expression in normal fibroblasts (NFs) induced the iCAF phenotype, and then iCAFs promoted PDAC progression through IL6 secretion in vitro. Furthermore, circCUL2-transduced NFs promoted tumorigenesis and metastasis of PDAC cells in vivo, which was blocked by an anti-IL6 antibody. Mechanistically, circCUL2 functioned as a ceRNA and modulated the miR-203a-3p/MyD88/NF-κB/IL6 axis, thereby further activating the STAT3 signaling pathway in pancreatic cancer cells to induce PDAC progression. Conclusions: We showed that the circCUL2/miR-203a-5p/MyD88/NF-κB/IL6 axis contributes to the induction of iCAFs and established a distinct fibroblast niche for PDAC progression, which could help the development of strategies that selectively target tumor-promoting CAFs in PDAC. [ABSTRACT FROM AUTHOR]

Long non-coding RNAs (lncRNAs) are important regulators in pathological processes, yet their potential roles in pancreatic ductal adenocarcinoma (PDAC) are poorly understood. Here, we found that a novel lncRNA, LOC389641, was upregulated in PDAC tissues and cell lines. The expression of LOC389641 was significantly correlated with staging, lymph node metastasis and overall survival. Knockdown of LOC389641 impaired cell proliferation and invasion and induced cell apoptosis in vitro, whereas overexpression of LOC389641 had the opposite effect. The growth promoting effect of LOC389641 was also demonstrated in vivo. Further, a significant negative correlation was observed between E-cadherin levels and LOC389641 levels in vivo. Knockdown of LOC389641 upregulated E-cadherin expression, but knockdown of E-cadherin had a limited influence on LOC389641. Importantly, after E-cadherin was inhibited, the enhancement of LOC389641 on cell invasion was hindered. Moreover, the expression of LOC389641 was closely associated with its genomic neighboring gene TNFRSF10A. Lastly, knockdown experiments showed that TNFRSF10A might be a connection between LOC389641and E-cadherin. We conclude that LOC389641 promotes PDAC progression and increases cell invasion by regulating E-cadherin with the possible involvement of TNFRSF10A. [ABSTRACT FROM AUTHOR]

Background: The results of laparoscopic pancreaticoduodenectomy combining with mesentericoportal vein resection and reconstruction (LPD-MPVRs) for pancreatic head adenocarcinoma are rarely reported. The aim of present study was to explore the short- and long-term outcomes of different type of LPD-MPVRs. Methods: Patients who underwent LPD-MPVRs in 14 Chinese high-volume pancreatic centers between June 2014 and December 2020 were selected and compared. Results: In total, 142 patients were included and were divided into primary closure (n = 56), end-end anastomosis (n = 43), or interposition graft (n = 43). Median overall survival (OS) and median progress-free survival (PFS) between primary closure and end-end anastomosis had no difference (both P > 0.05). As compared to primary closure and end-end anastomosis, interposition graft had the worst median OS (12 months versus 19 months versus 17 months, P = 0.001) and the worst median PFS (6 months versus 15 months versus 12 months, P < 0.000). As compared to primary closure, interposition graft had almost double risk in major morbidity (16.3 percent versus 8.9 percent) and about triple risk (10 percent versus 3.6 percent) in 90-day mortality, while End-end anastomosis had only one fourth major morbidity (2.3 percent versus 8.9 percent). Multivariate analysis revealed postoperation hospital stay, American Society of Anesthesiologists (ASA) score, number of positive lymph nodes had negative impact on OS, while R0, R1 surgical margin had protective effect on OS. Postoperative hospital stay had negative impact on PFS, while primary closure, end-end anastomosis, short-term vascular patency, and short-term vascular stenosis positively related to PFS. Conclusions: In LPD-MPVRs, interposition graft had the worst OS, the worst PFS, the highest rate of major morbidity, and the highest rate of 90-day mortality. While there were no differences in OS and PFS between primary closure and end-end anastomosis. [ABSTRACT FROM AUTHOR]

6K: overlap was found between the Transwell invasion assay Vector group and PLACT1+JSH-23 group; the correct image is now used (column 1, row 2) Graph The corrected figures are provided here. Correction: lncRNA-PLACT1 sustains activation of NF- B pathway through a positive feedback loop with I B /E2F1 axis in pancreatic cancer 2K: overlap was found between the Transwell migration assay and invasion assay in si-PLACT1#1 group of AsPC-1 cells; the representative image of the invasion assay in si-PLACT1#1 group of AsPC-1 cells has been replaced with the correct image Graph Fig. [Extracted from the article]

Background: Cancer-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. Methods: circRNA 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. Results: circFARP1 (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. Conclusions: The 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. [ABSTRACT FROM AUTHOR]

Background: While the best technique for pancreatic anastomosis during Whipple's procedure remains controversial, laparoscopic pancreaticoduodenectomy (LPD) has been rapidly increasing in popularity. Because of their feasibility and reliability, new pancreatic anastomosis techniques may have vital roles when adapted for LPD. Here, we describe a new pancreaticojejunostomy (PJ) technique using three sutures (termed the "three sutures" PJ technique), which facilitates pancreatic anastomosis during total LPD. Methods: A total of 149 patients who underwent LPD using the "three sutures" PJ technique at three hospitals were included in this study (81 patients at Guangdong Provincial People's Hospital [GDPH], 60 patients at Sun Yat-Sen Memorial Hospital [SMH], and 8 patients at Affiliated Hospital of Guangdong Medical University [AHGMU]). Data on the demographic characteristics, operative outcomes, and postoperative results (pancreatic fistula rate, mortality rate, and length of hospital stay) of these patients were collected and analyzed. Results: A surgical video showing the details of the "three sutures" PJ method was included. The mean operation times at GDPH, SMH, and AHGMU were 4.08 ± 0.99 h, 4.65 ± 1.53 h, and 4.67 ± 0.64 h, respectively, and the average PJ times were 17.96 ± 3.49 min, 18.19 ± 2.63 min, and 22.5 ± 3.96 min, respectively. The numbers of grade B pancreatic fistulas were 9 (11.11%), 2 (3.33%), and 1 (12.50%), respectively, and two patients had grade C fistulas, one each at GDPH and SMH. The numbers of clinically relevant postoperative pancreatic fistula (CR-POPF) were 10 (12.35%), 3 (5.00%), and 1 (12.50%) in each center, respectively. The overall rate of CR-POPF was 9.40% (14/149) among patients of all three centers. The perioperative mortality rate was 0%. Conclusions: The "three sutures" PJ technique for total LPD is a safe and reliable method, with a low risk of pancreatic fistula, short anastomosis time, and steep learning curve. [ABSTRACT FROM AUTHOR]

Background: Prophylactic somatostatin to reduce the incidence of clinically relevant postoperative pancreatic fistula after pancreaticoduodenectomy remains controversial. We assessed the preventive efficacy of somatostatin on clinically relevant postoperative pancreatic fistula in intermediate-risk patients who underwent pancreaticoduodenectomy at pancreatic centres in China. Methods: In this multicentre, prospective, randomised controlled trial, we used the updated postoperative pancreatic fistula classification criteria and cases were confirmed by an independent data monitoring committee to improve comparability between centres. The primary endpoint was the rate of clinically relevant postoperative pancreatic fistula within 30 days after pancreaticoduodenectomy. Results: Eligible patients (randomised, n = 205; final analysis, n = 199) were randomised to receive postoperative intravenous somatostatin (250 μg/h over 120 h; n = 99) or conventional therapy (n = 100). The primary endpoint was significantly lower in the somatostatin vs control group (n = 13 vs n = 25; 13% vs 25%, P = 0.032). There were no significant differences for biochemical leak (P = 0.289), biliary fistula (P = 0.986), abdominal infection (P = 0.829), chylous fistula (P = 0.748), late postoperative haemorrhage (P = 0.237), mean length of hospital stay (P = 0.512), medical costs (P = 0.917), reoperation rate (P > 0.99), or 30 days' readmission rate (P = 0.361). The somatostatin group had a higher rate of delayed gastric emptying vs control (n = 33 vs n = 21; 33% vs 21%, P = 0.050). Conclusions: Prophylactic somatostatin treatment reduced clinically relevant postoperative pancreatic fistula in intermediate-risk patients after pancreaticoduodenectomy. Trial registration: NCT03349424. [ABSTRACT FROM AUTHOR]

Background: The activation of NF-κB signaling pathway is regarded as the dominant process that correlates with tumorigenesis. Recently, increasing evidence shows that long noncoding RNAs (lncRNAs) play crucial roles in sustaining the NF-κB signaling pathway. However, the underlying mechanisms have not yet been elucidated. Methods: The expression and clinical features of PLACT1 were analyzed in a 166-case cohort of PDAC by qRT-PCR and in situ hybridization. The functional role of PLACT1 was evaluated by both in vitro and in vivo experiments. Chromatin isolation by RNA purification assays were utilized to examine the interaction of PLACT1 with IκBα promoter. Results: We identified a novel lncRNA-PLACT1, which was significantly upregulated in tumor tissues and correlated with progression and poor survival in PDAC patients. Moreover, PLACT1 promoted the proliferation and invasion of PDAC cells in vitro. Consistently, PLACT1 overexpression fostered the progression of PDAC both in orthotopic and lung metastasis mice models. Mechanistically, PLACT1 suppressed IκBα expression by recruiting hnRNPA1 to IκBα promoter, which led to increased H3K27me3 that decreased the transcriptional level of IκBα. Furthermore, E2F1-mediated overexpression of PLACT1 modulated the progression of PDAC by sustained activation of NF-κB signaling pathway through forming a positive feedback loop with IκBα. Importantly, administration of the NF-κB signaling pathway inhibitor significantly suppressed PLACT1-induced sustained activation of NF-κB signaling pathway, leading to reduced tumorigenesis in vivo. Conclusions: Our findings suggest that PLACT1 provides a novel epigenetic mechanism involved in constitutive activation of NF-κB signaling pathway and may represent a new therapeutic target of PDAC. [ABSTRACT FROM AUTHOR]

Macrophage-targeted therapy offers new options for intractable pancreatic ductal adenocarcinoma (PDAC), which has a low 5-year survival rate. However, the factors regulating the biological function and phenotype of macrophages in PDAC are incompletely understood. Here, we found that CD51 was positively associated with the poor prognosis of PDAC patients and was highly expressed on macrophages but not on pancreatic cancer cells. Subsequently, we found that CD51 was a marker of macrophages, which promoted the stemness of pancreatic cancer cells. Furthermore, knockdown of CD51 in macrophages drove macrophages toward an M1-like phenotype. Mechanistically, macrophage-expressed CD51 contributed to the acquisition of stemness traits of pancreatic cancer cells by regulating the TGF-β1/smad2/3 pathway. Our data demonstrate the central role played by macrophage-expressed CD51 in the acquisition of stemness traits of pancreatic cancer cells through the paracrine induction of TGF-β1. We first show the connection between the CD51/TGF-β1/smad2/3 axis and PDAC cancer stem cell properties and then indicate that CD51-targeted therapy is a new therapeutic modality for PDAC. [ABSTRACT FROM AUTHOR]

The present study aimed to determine how the expression and function of HOTTIP modifies, and regulates the metabotropic glutamate receptor 1 (mGluR1) to affect human pancreatic cancer cell viability. HOTTIP expression was higher in human pancreatic cancer tissue compared with in para-carcinoma tissue. However, downregulation of HOTTIP expression was revealed to significantly reduce cell viability, induce apoptosis, promote caspase-3 and caspase-8 activities and increase Bax expression in pancreatic cancer cells. Additionally, downregulation of HOTTIP expression significantly suppressed mGluR1 and mitigated activation of the phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway in pancreatic cancer cells. To the best of our knowledge, the present study is the first to identify that the anticancer effect of HOTTIP against human pancreatic cancer functions the mGluR1 pathway. [ABSTRACT FROM AUTHOR]

Our previous study demonstrated that long non-coding RNA (lncRNA) HOTTIP was maximally expressed in PDAC, and promoted cancer cell progression and epithelial to mesenchymal transition (EMT). Numerous studies indicated that lncRNAs or EMT supported cancer stem cells. However, the role of HOTTIP in pancreatic cancer stem cells (PCSCs) remains unclear. Here, we evaluated the role and mechanism of HOTTIP in PCSCs. First, we analyzed the relationship between HOTTIP expression and overall or disease-free survival in 90 patients with PDAC after radical resection. Patients with higher HOTTIP expression had shorter disease-free survival and overall survival than those with lower expression. Expression of HOTTIP and other lncRNAs was detected in PCSCs and non-PCSCs by laser capture microdissection (LCM). HOTTIP was highly expressed in PCSCs. In addition, in vitro assays showed that HOTTIP alterations affected stemness, including sphericity, tumorigenesis, and stem factors (LIN28, NANOG, OCT4, and SOX2) and markers (ALDH1, CD44, and CD133). Mechanistically, HOTTIP mediated HOXA9 to enhance the Wnt/β-catenin pathway by binding to WDR5 in PCSCs. In vivo results showed that HOTTIP or HOXA9 alterations influenced stemness. Our results indicate that the HOTTIP/WDR5/HOXA9/Wnt axis contributes to PCSC stemness and is a potential therapeutic target for PDAC. [ABSTRACT FROM AUTHOR]