GEM-resistant Pancreatic Cancer Research Articles

Cancer-associated fibroblast-derived COL17A1 promotes gemcitabine resistance and tumorigenesis in pancreatic cancer cells by interacting with ACTN4.

Cancer-associated fibroblasts (CAFs) are key components of tumor microenvironment and have been identified to be involved in modulating drug resistance in cancers by secreting molecules. Pancreatic cancer (PC) is a leading cause of cancer mortality with high aggressiveness. Gemcitabine (GEM) is one of primary antineoplastic drugs for PC. Collagen XVII (COL17A1) expression was found to be upregulated in GEM-resistant CAFs. Here, this study focused on investigating whether CAFs affected GEM resistance in PC by secreting COL17A1 and its associated mechanisms. In total, 60 newly diagnosed PC patients only with GEM-based chemotherapy were recruited. Normal fibroblasts (NFs) and CAFs were isolated using fresh normal and resistant PC tissues. Human pancreatic duct epithelial (HPDE) cells were used for functional analyses. Levels of COL17A1 and Actinin Alpha 4 (ACTN4) were measured by using qRT-PCR and western blotting. Functional analyses were conducted using MTT, 5-ethynyl-2'-deoxyuridine, transwell, and sphere formation assays, respectively. The interaction between COL17A1 and ACTN4 was analyzed by Co-immunoprecipitation and immunofluorescence assays. Animal models were established for in vivo analysis. CAF incubation promoted GEM resistance and enhanced the proliferation, invasion and stemness in GEM-resistant PC cells. COL17A1 was highly expressed in resistant CAFs and GEM-resistant PC cells, and CAF incubation could increase COL17A1 expression in resistant PC cells. Moreover, COL17A1 silencing in GEM-resistant PC cells or the incubation of COL17A1-decreased CAF with GEM-resistant PC cells could suppress GEM resistance and cell oncogenic phenotype progression. Mechanistically, COL17A1 interacted with ACTN4 protein, and the anticancer effects mediated by COL17A1-decreased CAFs in resistant PC cells were reversed by ACTN4 overexpression. In vivo assay also showed that COL17A1-decreased CAFs suppressed the growth and GEM resistance in PC by ACTN4. CAFs-derived COL17A1 promoted GEM resistance and tumorigenesis in PC by interacting with ACTN4, suggesting a new method for overcoming GEM resistance in PC.

A Novel circ_0075829/miR-326/GOT1 ceRNA Crosstalk Regulates the Malignant Phenotypes and Drug Sensitivity of Gemcitabine-Resistant Pancreatic Cancer Cells.

Although gemcitabine (GEM) is the cornerstone of the treatment of pancreatic cancer (PC), GEM resistance frequently arises. Circular RNA (circRNA) circ_0075829 is highly expressed in PC. However, whether circ_0075829 contributes to GEM resistance of PC is largely unknown. To generate GEM-resistant PC cells (BxPC-3/GR and SW1990/GR), we exposed GEM-sensitive PC cells to GEM. Circ_0075829, microRNA (miR)-326, and glutamic-oxaloacetic transaminase 1 (GOT1) were quantified by a qRT-PCR or western blot method. Cell survival and viability were gauged by MTS assay. Cell proliferation, apoptosis, invasion, and migration were assessed by EdU, flow cytometry, transwell, and wound-healing assays, respectively. Dual-luciferase reporter assays were used to verify the relationship between miR-326 and circ_0075829 or GOT1. Mouse xenografts were performed to evaluate the role of circ_0075829 in vivo. Our data showed that circ_0075829 was upregulated in GEM-resistant PC tissues and cells. Knockdown of circ_0075829 impeded the proliferation, invasion, migration, and glutamine metabolism, and promoted cell apoptosis and GEM sensitivity of GEM-resistant PC cells. Moreover, circ_0075829 silencing suppressed the tumorigenicity of SW1990/GR cells and sensitized them to the cytotoxic effect of GME in vivo. Mechanistically, circ_0075829 bound miR-326 and exerted regulatory effects by affecting miR-326 expression. GOT1 was a direct miR-326 target and a key downstream effector of miR-326. Furthermore, circ_0075829 modulated GOT1 expression via miR-326. Our findings establish a novel regulatory network, the circ_0075829/miR-326/GOT1 competing endogenous RNA (ceRNA) crosstalk, in the regulation of GEM resistance in PC.

Tumor-derived exosome PPP3CB induce gemcitabine resistance by regulating miR-298/STAT3 in pancreatic cancer

PurposeDue to resistance to gemcitabine (GEM), patients with pancreatic cancer (PC) usually have poor prognosis and low survival rate. The purpose of our research was to explore the impact of exosome PPP3CB on GEM resistance in PC, and concurrently analyze the regulatory role of the miR-298/STAT3 signaling pathway. MethodsExosomes isolated from PC cells were verified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting (WB). The interaction between PPP3CB and miR-298 was verified using dual-luciferase reporter gene assay, followed by evaluation of cell growth and death using CCK8 assay, EdU staining, and flow cytometry. ResultsIncreased PPP3CB expression was observed in GEM-resistant PC cells. Exosomes from PC cells and GEM-resistant PC cells were successfully extracted by ultra-high speed centrifugation. Confocal microscopy showed internalization of fluorescein amide (FAM)-labeled GEM-resistant exosomes by PC cells. PPP3CB enhanced the proliferation of GEM-resistant PC cells and inhibited their apoptosis, whereas down-regulation of PPP3CB promoted the death of PC cells and inhibited the proliferation of GEM-resistant PC cells, and enhance the susceptibility of PC cells to GEM. Additionally, PPP3CB positively regulated STAT3 expression in PC cells by down-regulating miR-298, thus promoting the growth and inhibiting the death of PC cells. ConclusionPC cell-derived exosome PPP3CB enhances STAT3 expression by downregulating miR-298, stimulating cell growth, and suppressing cell death, thereby increasing the resistance of PC cells to GEM.

Knockdown of TGF-β in Pancreatic Cancer Helps Ameliorate Gemcitabine Resistance.

The TGF-β gene is a gemcitabine (GEM) resistance gene; however, the mechanism by which it regulates GEM resistance in pancreatic cancer remains unclear. The PANC-1 cell line was treated with GEM and then stimulated with TGF-β. Subsequently, we constructed GEM-resistant pancreatic cancer cell lines, knocked down TGF-β in these cell lines, and detected changes in the proliferation and apoptosis of drug-resistant cancer cells. In addition, the protein expression levels of KLF-4, GFI-1, and ZEB-1 were determined. The xenograft tumor models of nude mice were constructed by subcutaneously injecting GEM-resistant PANC-1 cells into mouse axilla. The tumors were removed, dissected, and weighed after 6 weeks. The protein levels of KLF-4, GFI-1, and ZEB-1 in tumor tissues were quantified. In addition, the percentage of M2 macrophages in tumor tissues was determined using flow cytometry. The protein levels of TGF-β in pancreatic cancer cells were significantly decreased after GEM treatment. The protein expression of KLF-4 was downregulated, whereas the expressions of GFI-1 and ZEB-1 were upregulated after TGF-β stimulation. Apoptosis increased and proliferation decreased after TGF-β knockdown in GEM-resistant pancreatic cancer cells, moreover, silencing TGF-β promoted the expression of Caspase 3 and Cleaved caspase 3. In addition, the protein expression of KLF-4 was upregulated, whereas the expressions of GFI-1 and ZEB-1 were downregulated. Further, the volume and weight of the transplanted tumor decreased after TGF-β knockdown. The protein expression of KLF-4 was upregulated, whereas the expressions of GFI-1 and ZEB-1 were downregulated in tumor tissues. In addition, the percentage of M2 macrophages decreased in tumor tissues after TGF-β knockdown. The knockdown of TGF-β inhibits epithelial-to-mesenchymal transition, suppresses the proliferation and promotes the apoptosis of drug-resistant cancer cells, and decreases the macrophage polarization to the M2 phenotype, consequently ameliorating GEM resistance in pancreatic cancer.

E3 ubiquitin ligase UBR5 promotes gemcitabine resistance in pancreatic cancer by inducing O-GlcNAcylation-mediated EMT via destabilization of OGA.

Pancreatic cancer (PC) is among the deadliest malignancies, with an extremely poor diagnosis and prognosis. Gemcitabine (GEM) remains the first-line drug for treating PC; however, only a small percentage of patients benefit from current immunotherapies or targeted therapies. Resistance to GEM is prevalent and affects long-term survival. We found that ubiquitin-protein ligase E3 module N-recognition 5 (UBR5) is a therapeutic target against GEM resistance. UBR5 was markedly upregulated in clinical GEM-resistant PC samples and GEM-resistant PC cells. UBR5 knockdown markedly increased GEM sensitivity in GEM-resistant PC cell lines. UBR5-mediated GEM resistance was accompanied by activation of epithelial-mesenchymal transition (EMT) and could be mitigated by inhibiting EMT. Further analysis revealed that UBR5 promoted GEM resistance in PC cells by enhancing O-GlcNAcylation-mediated EMT. In addition, UBR5 knockdown resulted in increased O-GlcNAase (OGA) levels, an essential negatively regulated enzyme in the O-GlcNAcylation process. We identified a negative association between OGA and UBR5 levels, which further supported the hypothesis that O-GlcNAcylation-mediated GEM resistance induced by UBR5 is OGA-dependent in PC cells. Mechanistic studies revealed that UBR5 acts as an E3 ubiquitin ligase of OGA and regulates O-GlcNAcylation by binding and modulating OGA, facilitating its degradation and ubiquitination. Additionally, high-throughput compound library screening using three-dimensional protein structure analysis and drug screening identified a Food and Drug Administration drug, Y-39983 dihydrochloride, as a potent GEM sensitiser and UBR5 inhibitor. The combination of Y-39983 dihydrochloride and GEM attenuated tumour growth in a mouse xenograft tumour model. Collectively, these data demonstrated that UBR5 plays a pivotal role in the sensitisation of PC to GEM and provides a potential therapeutic strategy to overcome GEM resistance.

Hyperthermia improves gemcitabine sensitivity of pancreatic cancer cells by suppressing the EFNA4/β-catenin axis and activating dCK

BackgroundPreviously, our investigations have underscored the potential of hyperthermia to improve the therapeutic efficacy of gemcitabine (GEM) in pancreatic cancer (PC). Nonetheless, the precise underlying mechanisms remain elusive. MethodsWe engineered two GEM-resistant PC cell lines (BxPC-3/GEM and PANC-1/GEM) and treated them with GEM alongside hyperthermia. The impact of hyperthermia on the therapeutic potency of GEM was ascertained through MTT assay, assessment of the concentration of its active metabolite dFdCTP, and evaluation of deoxycytidine kinase (dCK) activity. Lentivirus-mediated dCK silencing was further employed to validate its involvement in mediating the GEM-sensitizing effect of hyperthermia. The mechanism underlying hyperthermia-mediated dCK activation was explored using bioinformatics analyses. The interplay between hyperthermia and the ephrin A4 (EFNA4)/β-catenin/dCK axis was investigated, and their roles in GEM resistance was further explored via the establishment of xenograft tumor models in nude mice. ResultsHyperthermia restored dCK expression in GEM-resistant cell lines, concurrently enhancing GEM sensitivity and fostering DNA damage and cell death. These observed effects were negated by dCK silencing. Regarding the mechanism, hyperthermia activated dCK by downregulating EFNA4 expression and mitigating β-catenin activation. Overexpression of EFNA4 activated the β-catenin while suppressing dCK, thus diminishing cellular GEM sensitivity—a phenomenon remediated by the β-catenin antagonist MSAB. Consistently, in vivo, hyperthermia augmented the therapeutic efficacy of GEM on xenograft tumors through modulation of the ephrin A4/β-catenin/dCK axis. ConclusionThis study delineates the role of hyperthermia in enhancing GEM sensitivity of PC cells, primarily mediated through the suppression of the EFNA4/β-catenin axis and activation of dCK.

Visualization research on ENT1/NIS dual-function gene therapy to reverse drug resistance mediated by MUC1 in GEM-resistant pancreatic cancer

PurposeTo use bifunctional target genes to increase the intracellular transport of gemcitabine (GEM) to reverse chemotherapy resistance and to simultaneously use reporter gene imaging to localize therapeutic genes. The therapeutic effect was evaluated by [18F]FLT PET/CT to visualize the effect of gene therapy. MethodsA viral gene vector containing the pancreatic cancer-targeting promoter MUC1 for specific transcription of equilibrative nucleoside transporter 1 (ENT1) and NIS (nuclide transport channel) was employed. [125I]NaI uptake tests and [131I]NaI SPECT imaging were performed to verify the function of NIS and the target function of MUC1. The correlation between [18F]FLT uptake and GEM resistance were assessed, and the influence ENT1 and thymidine kinase 1 (TK1) expression on [18F]FLT micro-PET/CT was measured, which provides a theoretical basis for the use of [18F]FLT micro-PET/CT to evaluate the efficacy of gene therapy. ResultsFirst, functions of gene therapy were confirmed: ENT1 reversed the drug resistance of GEM-resistant pancreatic cancer cells by increasing GEM intracellular transport; MUC1 drove NIS target gene expression in pancreatic cancer; and therapeutic genes could be localized using [131I]NaI SPECT reporter gene imaging. Second, the [18F]FLT uptake ratio was affected by drug resistance and GEM treatment. The mechanism underlying this effect was related to ENT1 and TK1. Increased expression of ENT1 inhibited the expression of TK1 after GEM chemotherapy to reduce the uptake of [18F]FLT. Finally, micro-PET/CT indicated that the SUVmax of [18F]FLT could predict survival time. SUVmax exhibited an increasing trend in resistant pancreatic cancer but a trend of inhibition after upregulation of ENT1, which was more significant after GEM treatment. ConclusionsBifunctional targeted genes can localize therapeutic genes through reporter gene imaging, reverse the drug resistance of GEM-resistant pancreatic cancer and be visually evaluated through [18F]FLT micro-PET/CT.

CircACTR2 attenuates gemcitabine chemoresiatance in pancreatic cancer through PTEN mediated PI3K/AKT signaling pathway

BackgroundRecently, accumulating studies have unveiled that circRNAs exert critical function in a variety of tumor biological processes including chemoresistance. Our previous study has found circACTR2 is significantly down-regulated in acquired gemcitabine (GEM)- resistant pancreatic cancer (PC) cells, which has not been well-explored. Our study aimed to research the function and molecular mechanism of circACTR2 in PC chemoresistance.MethodsqRT-PCR and western blot analysis was performed to detect gene expression. The effect of circACTR2 on PC GEM resistance were examined by CCK-8 and flow cytometry assays. Whether circACTR2 could sponge miR-221-3p and regulate PTEN expression were determined by bioinformatics analysis, RNA pull-down, and Dual-luciferase reporter assay.ResultscircACTR2 was notably down-regulated in a panel of GEM-resistant PC cells lines, and negatively associated with aggressive phenotype and poor prognosis of PC. circACTR2 downregulation contributed to GEM chemoresistance of PC cells with decreased S phase ratio of cell cycle and cell apoptosis, as confirmed by gain- and loss-of-function assays in vitro. In addition, circACTR2 overexpression retarded GEM resistance in vivo. Further, circACTR2 acted as a ceRNA against miR-221-3p, which directly targeted PTEN. The mechanistic studies revealed that loss of circACTR2 promoted GEM resistance in PC through activating the PI3K/AKT signaling pathway by downregulating PTEN expression in a miR-221-3p dependent manner.ConclusionscircACTR2 reversed the chemoresistance of PC cells to GEM through inhibiting PI3K/AKT signaling pathway by sponging miR-221-3p and upregulating PTEN expression.

Cancer-associated fibroblasts suppress ferroptosis and induce gemcitabine resistance in pancreatic cancer cells by secreting exosome-derived ACSL4-targeting miRNAs

BackgroundPancreatic cancer continues to be one of the world's most lethal cancers. Chemotherapy resistance in patients with advanced pancreatic cancer often accompany with dismal prognosis, highlighting the need to investigate mechanisms of drug resistance and develop therapies to overcome chemoresistance. MethodsThis research was filed with the Chinese Clinical Trial Registry (ChiCTR2200061320). In order to isolate primary normal fibroblasts (NFs) and cancer-associated fibroblasts (CAFs) samples of pancreatic ductal adenocarcinoma (PDAC) and paracancerous pancreatic tissue from individuals diagnosed with PDAC were obtained. The exosomes were obtained using ultracentrifugation, and their characteristics were determined by Western blotting, nanoparticle tracking analysis, and transmission electron microscopy. CAF-derived miRNAs were analyzed by RT-qPCR and high-throughput sequencing. Gemcitabine (GEM) was employed to promote ferroptosis, and ferroptosis levels were determined by monitoring lipid reactive oxygen species (ROS), cell survival, and intracellular Fe2+ concentrations. To assess in vivo tumor response to GEM therapy, a xenograft tumor mouse model was utilized. ResultsExosomes derived from CAFs in PDAC did not exhibit innate GEM resistance. CAFs promoted chemoresistance in PDAC cells following GEM treatment by secreting exosomes, and maintaining signaling communication with cancer cells. Mechanistically, miR-3173–5p derived from CAF exosomes sponged ACSL4 and inhibited ferroptosis after uptake by cancer cells. ConclusionThis work demonstrates a novel mode of acquired chemoresistance in PDAC and identifies the miR-3173–5p/ACSL4 pathway as a promising treatment target for GEM-resistant pancreatic cancer.

LncRNA SNHG6 Upregulates KPNA5 to Overcome Gemcitabine Resistance in Pancreatic Cancer via Sponging miR-944.

Gemcitabine (GEM) is the gold-standard therapeutic regimen for patients with pancreatic cancer (PC); however, patients may receive limited benefits due to the drug resistance of GEM. LncRNA SNHG6 is reported to play key roles in drug resistance, but its role and molecular mechanism in PC remain incompletely understood. We found that LncRNA SNHG6 is drastically downregulated in GEM-resistant PC and is positively correlated with the survival of PC patients. With the help of bioinformatic analysis and molecular approaches, we show that LncRNA SNHG6 can sponge miR-944, therefore causing the upregulation of the target gene KPNA5. In vitro experiments showed that LncRNA SNHG6 and KPNA5 suppress PC cell proliferation and colony formation. The Upregulation of LncRNA SNHG6 and KPNA5 increases the response of GEM-resistant PANC-1 cells to GEM. We also show that the expression of KPNA5 is higher in patients without GEM resistance than in those who developed GEM resistance. In summary, our findings indicate that the LncRNA SNHG6/miR944/KPNA5 axis plays a pivotal role in overcoming GEM resistance, and targeting this axis may contribute to an increasing of the benefits of PC patients from GEM treatment.

CircLMTK2 Silencing Attenuates Gemcitabine Resistance in Pancreatic Cancer by Sponging miR-485-5p and to Target PAK1

Pancreatic cancer (PC) has a high degree of malignancy and poor prognosis, and countless patients have distant metastasis when diagnosed. Gemcitabine (GEM) chemotherapy is one of the main ways of treatment. However, PC cells have been displayed chemoresistance to GEM during treatment. Circular RNAs (circRNAs) have been demonstrated to be the most popular diagnostic and prognostic biomarkers in PC with GEM resistance. Here, we assessed the potential of circLMTK2 in the GEM resistance of PC cells. Functional assays were implemented to measure the impacts of circLMTK2 on the proliferation, migration/invasion, and apoptosis of GEM-resistant PC cells. Bioinformatics analysis and mechanical experiments displayed the underlying mechanism of circLMTK2 in GEM-resistant PC cells. We found that circLMTK2 was upregulated in PC and GEM-resistant PC tissues and cells. CircLMTK2 knockdown suppressed proliferation, invasion, migration, and enhanced apoptosis in GEM-resistant PC cells. Moreover, circLMTK2 silencing could decrease GEM resistance-associated tumor size in vivo. In terms of mechanism, circLMTK2 served as a sponge for miR-485-5p, and miR-485-5p bound to p21 (RAC1) activated kinase 1 (PAK1), which were clarified via the dual-luciferase assay in PC cell lines. We confirmed that circLMTK2 knockdown attenuated GEM-resistant PC cells by regulating PAK1 via miR-485-5p. Our study demonstrated that circLMTK2 may be a novel diagnostic and prognostic biomarker in GEM-resistant PC cells.

Phosphomimetic Dicer S1016E triggers a switch to glutamine metabolism in gemcitabine-resistant pancreatic cancer

ObjectiveDicer is an enzyme that processes microRNAs (miRNAs) precursors into mature miRNAs, which have been implicated in various aspects of cancer progressions, such as clinical aggressiveness, prognosis, and survival outcomes. We previously showed that high expression of Dicer is associated with gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC); thus, in this study, we aimed to focus on how Dicer is involved in GEM resistance in PDAC, including cancer prognosis, cell proliferation, and metabolic regulation. MethodsWe generated stable shRNA knockdown of Dicer in GEM-resistant PANC-1 (PANC-1 GR) cells and explored cell viability by MTT and clonogenicity assays. Metabolomic profiling was employed to investigate metabolic changes between parental cells, PANC-1, and PANC-1 GR cells, and further implied to compare their sensitivity to the glutaminase inhibitor, CB839, and GEM treatments. To identify putative phosphorylation site involves with Dicer and its effects on GEM resistance in PDAC cells, we further generated phosphomimetic or phosphomutant Dicer at S1016 site and examined the changes in drug sensitivity, metabolic alteration, and miRNA regulation. ResultsWe observed that high Dicer levels in pancreatic ductal adenocarcinoma cells were positively correlated with advanced pancreatic cancer and acquired resistance to GEM. Metabolomic analysis indicated that PANC-1 GR cells rapidly utilised glutamine as their major fuel and increased levels of glutaminase (GLS): glutamine synthetase (GLUL) ratio which is related to high Dicer expression. In addition, we found that phosphomimetic Dicer S1016E but not phosphomutant Dicer S1016A facilitated miRNA maturation, causing an imbalance in GLS and GLUL and resulting in an increased response to GLS inhibitors. ConclusionOur results suggest that phosphorylation of Dicer on site S1016 affects miRNA biogenesis and glutamine metabolism in GEM-resistant pancreatic cancer.

Gemcitabine-Loaded Albumin Nanoparticle Exerts An Antitumor Effect on Gemcitabine-Resistant Pancreatic Cancer Cells Induced by MDR1 and MRP1 Overexpression in Vitro.

PurposeGemcitabine (GEM) is the first-line chemotherapeutic drug for pancreatic cancer treatment in clinical practice. However, many reasons can reduce the efficacy of GEM, among which the high expression of ATP-binding cassette (ABC) transporters is a significant factor. In this study, we aimed to investigate the antitumor effect of gemcitabine-loaded human serum albumin nanoparticle (GEM-HSA-NP) on GEM-resistant pancreatic cancer cells induced by the high expression of ABC transporters, namely multidrug resistance protein 1/P-gp/ABCB1 (MDR1) and multidrug resistance-associated protein 1/ ABCC1 (MRP1).MethodsMDR1 and MRP1 were stably overexpressed via lentiviral transduction in the pancreatic cancer cell lines BxPC3 and PANC1. Proliferation inhibition assays, cell cycle arrest and apoptosis analyses were conducted to examine the antitumor effect of GEM-HSA-NP. In addition, intracellular ATP levels were determined to explore the potential mechanisms implicated preliminarily.ResultsWhen administered to GEM-resistant cancer cells, GEM-HSA-NP displayed its antitumor effect by promoting the inhibition of proliferation, cell cycle arrest, and apoptosis induction. Intracellular ATP depletion, caused by the albumin component of GEM-HSA-NP was proposed to be potentially involved in the modulation of ABC transporter activity.ConclusionGEM-HSA-NP can effectively overcome GEM-resistance induced by MDR1 and MRP1 overexpression, which highlights its potential value in a clinical setting.

4-Acetylantroquinonol B enhances cell death and inhibits autophagy by downregulating the PI3K/Akt/MDR1 pathway in gemcitabine-resistant pancreatic cancer cells.

Gemcitabine (GEM) is a typical chemotherapeutic drug used to treat pancreatic cancer, but GEM resistance develops within weeks after chemotherapy. Hence, the development of a new strategy to overcome drug resistance is urgent. 4-Acetylantroquinonol B (4-AAQB), a ubiquinone derived from Taiwanofungus camphoratus, has hepatoprotective, anti-obesity, and antitumor activities. However, the role of 4-AAQB in enhancing GEM sensitivity is unclear. This study aimed to determine the underlying mechanisms by which 4-AAQB enhances cytotoxicity and GEM sensitivity. Cell viability was dramatically reduced by 4-AAQB (2 and 5 µM) treatment in the MiaPaCa-2 and GEM-resistant MiaPaCa-2 (MiaPaCa-2GEMR) human pancreatic cancer cells. 4-AAQB led to cell cycle arrest, upregulated the levels of reactive oxygen species (ROS), promoted apoptosis, and inhibited autophagy, which subsequently enhanced GEM chemosensitivity by suppressing the receptor for advanced glycation end products (RAGE)/high mobility group box 1 (HMGB1)-initiated PI3K/Akt/multidrug resistance protein 1 (MDR1) signaling pathway in both cell lines. Vascular endothelial growth factor A (VEGFA) expression, cell migration, and invasion were also inhibited by the 4-AAQB incubation. Overall, this combination treatment strategy might represent a novel approach for GEM-resistant pancreatic cancer.

Exosomal lncRNA UCA1 Derived From Pancreatic Stellate Cells Promotes Gemcitabine Resistance in Pancreatic Cancer via the SOCS3/EZH2 Axis.

ObjectivePancreatic cancer is associated with poor prognosis and dismal survival rates. This study aims to investigate roles of lncRNA UCA1-loaded exosomes secreted by pancreatic stellate cells (PSCs) in Gemcitabine (Gem) resistance of pancreatic cancer under hypoxia, which involves the methylation of SOCS3 and EZH2 recruitment.MethodsThe exosomes were isolated from PSCs and hypoxic PSCs (HPSCs), and co-cultured with pancreatic cancer cells transduced with manipulated lncRNA UCA1, EZH2, and SOCS3. The interaction among lncRNA UCA1, EZH2, and SOCS3 was characterized by RIP and ChIP assays. Next, MTT assay, flow cytometry and TUNEL staining and Transwell assay were used to detect cell viability, apoptosis, invasion, and migration. Gem-resistant pancreatic cancer cell line (GemMIA-R3) was established, which was applied in a mouse xenograft model of pancreatic cancer, with MTT assay to determine Gem sensitivity.ResultsLncRNA UCA1 was highly expressed, while SOCS3 was poorly expressed in pancreatic cancer tissues. Hypoxia induced activation of PSCs and promoted release of exosomes. LncRNA UCA1 delivered by hypoxic PSC-derived exosomes (HPSC-EXO) regulated histone methylation level in SOCS3 gene region through recruitment of EZH2. In vitro and in vivo experimental results confirmed that lncRNA UCA1-loaded HPSC-EXO promoted malignant phenotypes, inhibited apoptosis, and promoted Gem resistance of pancreatic cancer cells as well as tumorigenesis in mice.ConclusionUnder hypoxic conditions, exosomes secreted by hypoxia-induced PSCs deliver lncRNA UCA1 into pancreatic cancer cells, where lncRNA UCA1 recruits EZH2 and regulates histone methylation level in SOCS3 gene region, thereby augmenting pancreatic cancer resistance to Gem.

LncRNA HIF1A-AS1 Promotes Gemcitabine Resistance of Pancreatic Cancer by Enhancing Glycolysis through Modulating the AKT/YB1/HIF1α Pathway

Gemcitabine (GEM) resistance is a major challenge for chemotherapy of pancreatic cancer. Previous studies have reported on the role of long noncoding RNA (lncRNA) in tumorigenesis of pancreatic cancer, however, the involvement of lncRNA in the development of GEM resistance of pancreatic cancer remains unclear. In the present study, we demonstrated that the antisense RNA1 of HIF1α (HIF1A-AS1) was significantly elevated in the GEM-resistant pancreatic cancer cells. Gain- and lost-of-function experiments validated that HIF1A-AS1 promoted GEM resistance of pancreatic cancer cells both in vitro and vivo. We further revealed that HIF1A-AS1 upregulated HIF1α expression and thus promoted glycolysis to enhance GEM resistance of pancreatic cancer cells. Mechanistically, HIF1A-AS1 facilitated the interaction between serine/threonine kinase AKT and Y-box-binding protein 1 (YB1), which promoted phosphorylation of YB1 (pYB1). Meanwhile, HIF1A-AS1 recruited pYB1 to HIF1α mRNA that consequently promoted translation of HIF1α. Furthermore, HIF1α promoted HIF1A-AS1 transcription by directly binding to the HIF1α response element in the promoter area of HIF1A-AS1 to form a positive feedback. Consistently, both HIF1A-AS1 and HIF1α were upregulated in pancreatic cancer tissues and associated with poor overall survival. Together, our results underline a reciprocal loop of HIF1A-AS1 and HIF1α that contributes to GEM resistance of pancreatic cancer and indicate that HIF1A-AS1 might serve as a novel therapeutic target for GEM resistance of pancreatic cancer. SIGNIFICANCE: These findings show that a reciprocal feedback of HIF1A-AS1 and HIF1α promotes gemcitabine resistance of pancreatic cancer, which provides an applicable therapeutic target.

The enhancement of Tetrandrine to gemcitabine-resistant PANC-1 cytochemical sensitivity involves the promotion of PI3K/Akt/mTOR-mediated apoptosis and AMPK-regulated autophagy

BackgroundIn the process of tumor development, the resistance of pancreatic cancer cells to gemcitabine (GEM) is mainly due to the suppression and dysregulation of apoptosis signals to a large extent. Therefore, it is very necessary to develop pro-apoptotic drugs for combined treatment of pancreatic cancer to increase the activity of GEM and improve the prognosis of pancreatic cancer. Methods and ResultsGEM-resistant PANC-1 cells were treated with increasing doses of GEM. The effects of GEM and TET on apoptosis were evaluated by flow cytometry and Hoechst 33258 staining. We also evaluated the expression of survivin by real-time PCR, and the expression levels of proteins involved in apoptosis, autophagy, and PI3K/Akt/mTOR signaling were detected by western blotting. The results showed that TET downregulated expression of survivin by inhibiting the PI3K/Akt/mTOR signaling pathway to promote pancreatic cancer cell apoptosis, thereby enhancing pancreatic cancer cell sensitivity to GEM. Moreover, TET enhanced cytotoxic and autophagy-dependent cell death by upregulating the AMPK-autophagy axis, and this effect was reversed by inhibition of AMPK. ConclusionsTET promotes apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway and promotes autophagy via up-regulating the AMPK signaling pathway to play an anti-tumor effect in GEM-resistant pancreatic cancer cells, which represents a new therapeutic strategy for the treatment of GEM-resistant pancreatic cancer.

Ursolic acid restores sensitivity to gemcitabine through the RAGE/NF-κB/MDR1 axis in pancreatic cancer cells and in a mouse xenograft model.

Gemcitabine (GEM) is a first-line drug for pancreatic cancer therapy, but GEM resistance is easily developed in patients. Growing evidence suggests that cancer chemoprevention and suppression are highly associated with dietary phytochemical and microbiota composition. Ursolic acid (UA) has anti-inflammatory and anticancer effects; however, its role in improving cancer drug resistance in vivo remains unclear. In this study, the aim was to explore the role of UA in managing drug resistance-associated molecular mechanisms and the influence of gut microbiota. The in vitro results showed that receptor for advanced glycation end products (RAGE), nuclear factor kappa B p65 (NF-κB/p65), and multidrug resistance protein 1 (MDR1) protein levels were significantly increased in GEM-resistant pancreatic cancer cells (named MIA PaCa-2 GEMR) compared to MIA PaCa-2 cells. Downregulation of RAGE, pP65, and MDR1 protein expression not only was observed following UA treatment but also was seen in MIA PaCa-2 GEMR cells after transfection with a RAGE siRNA. Remarkably, the enhanced effects of UA coupled with GEM administration dramatically suppressed the RAGE/NF-κB/MDR1 cascade and consequently inhibited subcutaneous tumor growth. Moreover, UA could increase alpha diversity and regulate the composition of gut microbiota, especially in Ruminiclostridium 6. Taken together, these results provide the first direct evidence of MDR1 attenuation and chemosensitivity enhancement through inhibition of the RAGE/NF-κB signaling pathway in vitro and in vivo, implying that UA may be used as an adjuvant for the treatment of pancreatic cancer in the future.

Everolimus regulates the activity of gemcitabine-resistant pancreatic cancer cells by targeting the Warburg effect via PI3K/AKT/mTOR signaling

BackgroundGemcitabine (GEM) resistance remains a significant clinical challenge in pancreatic cancer treatment. Here, we investigated the therapeutic utility of everolimus (Evr), an inhibitor of mammalian target of rapamycin (mTOR), in targeting the Warburg effect to overcome GEM resistance in pancreatic cancer.MethodsThe effect of Evr and/or mTOR overexpression or GEM on cell viability, migration, apoptosis, and glucose metabolism (Warburg effect) was evaluated in GEM-sensitive (GEMsen) and GEM-resistant (GEMres) pancreatic cancer cells.ResultsWe demonstrated that the upregulation of mTOR enhanced cell viability and favored the Warburg effect in pancreatic cancer cells via the regulation of PI3K/AKT/mTOR signaling. However, this effect was counteracted by Evr, which inhibited aerobic glycolysis by reducing the levels of glucose, lactic acid, and adenosine triphosphate and suppressing the expression of glucose transporter 1, lactate dehydrogenase-B, hexokinase 2, and pyruvate kinase M2 in GEMsen and GEMres cells. Evr also promoted apoptosis by upregulating the pro-apoptotic proteins Bax and cytochrome-c and downregulating the anti-apoptotic protein Bcl-2. GEM was minimally effective in suppressing GEMres cell activity, but the therapeutic effectiveness of Evr against pancreatic cancer growth was greater in GEMres cells than that in GEMsen cells. In vivo studies confirmed that while GEM failed to inhibit the progression of GEMres tumors, Evr significantly decreased the volume of GEMres tumors while suppressing tumor cell proliferation and enhancing tumor apoptosis in the presence of GEM.ConclusionsEvr treatment may be a promising strategy to target the growth and activity of GEM-resistant pancreatic cancer cells by regulating glucose metabolism via inactivation of PI3K/AKT/mTOR signaling.

Ursolic acid promotes apoptosis, autophagy, and chemosensitivity in gemcitabine-resistant human pancreatic cancer cells.

Gemcitabine (GEM) resistance in pancreatic adenocarcinoma mediated by the receptor for advanced glycation end products (RAGE) has been demonstrated. Therefore, investigating the safety and the potential of new auxiliary methods for pancreatic cancer treatment is urgent. Ursolic acid (UA), a natural pentacyclic triterpenoid found in apple peels, rosemary, and thyme, has been reported to have anticancer capacity. This study aimed to reveal the underlying mechanisms of UA in cell death and drug enhancement, especially in GEM-resistant pancreatic cancer cells. First, GEM-resistant cells (MIA Paca-2GEMR cells) were established by incrementally increasing GEM culture concentrations. UA treatment reduced cell viability through cell cycle arrest and endoplasmic reticulum (ER) stress, resulting in apoptosis and autophagy in a dose-dependent manner in MIA Paca-2 and MIA Paca-2GEMR cells. High RAGE expression in MIA Paca-2GEMR cells was suppressed by UA treatment. Interestingly, knocking down RAGE expression showed similar UA-induced effects in both cell lines. Remarkably, UA had a drug-enhancing effect by decreasing cell viability and increasing cell cytotoxicity when combined with GEM treatment. In conclusions, UA triggered ER stress, subsequently regulating apoptosis- and autophagy-related pathways and increasing GEM chemosensitivity in pancreatic cancer cells by inhibiting the expression of RAGE.