Gemcitabine-resistant Pancreatic Cancer Research Articles

TRIM11 suppresses ferritinophagy and gemcitabine sensitivity through UBE2N/TAX1BP1 signaling in pancreatic ductal adenocarcinoma.

Gemcitabine is first-line chemotherapy for pancreatic cancer, however, the development of resistance limits its effectiveness. The tripartite motif-containing 11 (TRIM11) protein plays crucial roles in tumor development and undergoes auto-polyubiquitination to promote interactions in selective autophagy. Therefore, Understanding whether TRIM11 is involved in ferritinophagy and gemcitabine resistance in pancreatic cancer is critical in developing pancreatic cancer therapeutics. TRIM11 expression was validated by Western blot analysis, real-time polymease chain reaction, and immunohistochemical staining. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Colony formation assays were performed to investigate pancreatic ductal adenocarcinomas (PDAC) cell viability. Mouse xenograft model of PDAC cells was established to verify the role of TRIM11 in vivo. Coimmunoprecipitation was used to identify the reciprocal regulation between TRIM11 and UBE2N. In this study, we found that TRIM11 expression were higher in PDAC cells and tissues. TRIM11 overexpression promotes PDAC cell proliferation in vitro and tumor growth in vivo. Decreased expression of TRIM11 in PDAC patients is associated with decreased UBE2N and increased TAX1BP1 expression. Coimmunoprecipitation established that TRIM11 interacts and colocalizes with UBE2N. Mechanistically, TRIM11 promoted gemcitabine resistance and suppressed ferritinophagy through UBE2N-TAX1BP1 signaling. Our findings identify TRIM11 as a key regulator of TAX1BP1 signaling with a crucial role in ferritinophagy and gemcitabine resistance in PDAC.

EMT-Induced Gemcitabine Resistance in Pancreatic Cancer Involves the Functional Loss of Equilibrative Nucleoside Transporter 1.

Epithelial-mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, membrane localization, and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, membrane localization, and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM-positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed IHC analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface coexpression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT.

S100A14 promotes progression and gemcitabine resistance in pancreatic cancer

S100 calcium binding protein A14 (S100A14) plays an important role in the progression of several types of cancer. However, its roles in pancreatic ductal adenocarcinoma (PDAC) are largely unexplored. Here, we characterized the functional roles of S100A14 in the progression and chemoresistance of PDAC. Gene expression microarray identified that S100A14 was significantly highly expressed in four pairs of human PDAC tumor compared with corresponding non-tumor tissues genes. Quantitative reverse transcription PCR (qRT-PCR), western blotting and immunohistochemical staining (IHC) showed that S100A14 was frequently overexpressed in PDAC cell lines and tissues. Moreover, expression level of S100A14 was positively correlated to advanced cancer stages. Further, Kaplan-Meier survival analysis suggested that PDAC patients with low S100A14 expression had longer overall survival in TCGA PDAC datasets. Transient overexpressing of S100A14 promoted cell proliferation, anchorage-independent colony formation, cell migration and invasion in cell lines with low endogenous S100A14 levels, while transient silencing of S100A14 inhibited cell proliferation, anchorage-independent colony formation, cell migration and invasion in cell lines with high endogenous S100A14 levels. Persistent knockdown of S100A14 by transducing shRNAs carrying lentivirus inhibited subcutaneous tumor formation in nude mice, and sensitized the PDAC cells to gemcitabine treatment. Taken together, S100A14 exhibited oncogenic properties by promoting cell proliferation, transformation, migration and invasion, and enhanced in vivo tumor growth. More importantly, inhibition of S100A14 could effectively abrogate the cancerous properties of the PDAC cells. Our study indicated that S100A14 was a valuable target for the development of therapeutic strategy, as well as a diagnostic and prognosis biomarker for PDAC patients.

A MET Targeting Antibody-Drug Conjugate Overcomes Gemcitabine Resistance in Pancreatic Cancer.

Pancreatic cancer is an aggressive disease associated with a poor 5-year overall survival. Most patients are ineligible for surgery due to late diagnosis and are treated primarily with chemotherapy with very limited success. Pancreatic cancer is relatively insensitive to chemotherapy due to multiple factors, including reduced bioavailability of drugs to tumor cells. One strategy to improve drug efficacy with reduced toxicity is the development of antibody-drug conjugates (ADC), which have now been used successfully to treat both solid and liquid tumors. Here, we evaluate the efficacy of TR1801-ADC, a newly developed ADC composed of a MET antibody conjugated to the highly potent pyrrolobenzodiazepine toxin-linker, tesirine. We first evaluated MET expression and subcellular localization in pancreatic cancer cell lines, human tumors, and patient-derived xenografts (PDX). We then tested TR1801-ADC efficacy in vitro in pancreatic cancer cell lines. Preclinical evaluation of TR1801-ADC efficacy was conducted on PDXs selected on the basis of their MET expression level. We show that MET is highly expressed and located at the plasma membrane of pancreatic cancer cells. We found that TR1801-ADC induces a specific cytotoxicity in pancreatic cancer cell lines and a profound tumor growth inhibition, even in a gemcitabine-resistant tumor. We also noted synergism between TR1801-ADC and gemcitabine in vitro and an improved response to the combination in vivo. Together, these results suggest the promise of agents such as TR1801-ADC as a novel approach to the treatment of pancreatic cancer.

The tumor microenvironment contributes to gemcitabine resistance in pancreatic cancer: a narrative review

The tumor microenvironment contributes to gemcitabine resistance in pancreatic cancer: a narrative review

MicroRNA-7 modulates cellular senescence to relieve gemcitabine resistance by targeting PARP1/NF-κB signaling in pancreatic cancer cells.

Senescence is activated in response to gemcitabine to prevent the propagation of cancer cells. However, there is little evidence on whether senescence is involved in gemcitabine resistance in pancreatic cancer. Increasing evidence has demonstrated that microRNAs (miRs) are potential regulators of cellular senescence. The present study aimed to investigate whether aberrant miR-7 expression modulated senescence to influence pancreatic cancer resistance to chemotherapy. In the present study, cell senescence assay, ALDEFLUOR™ assay, luciferase reporter assay, flow cytometry, quantitative PCR, immunohistochemistry and western blot analysis were performed to explore the association between senescence and gemcitabine therapy response, and to clarify the underlying mechanisms. The present study revealed that gemcitabine-induced chronically existing senescent pancreatic cells possessed stemness markers. Therapy-induced senescence led to gemcitabine resistance. Additionally, it was found that miR-7 expression was decreased in gemcitabine-resistant pancreatic cancer cells, and that miR-7 acted as an important regulator of cellular senescence by targeting poly (ADP-ribose) polymerase 1 (PARP1)/NF-κB signaling. When miR-7 expression was restored, it was able to sensitize pancreatic cancer cells to gemcitabine. In conclusion, the present study demonstrated that miR-7 regulated cellular senescence and relieved gemcitabine resistance by targeting the PARP1/NF-κB axis in pancreatic cancer cells.

Research advances of intracellular mechanisms underlying gemcitabine resistance in pancreatic cancer

Research advances of intracellular mechanisms underlying gemcitabine resistance in pancreatic cancer

ERK-mediated transcriptional activation of Dicer is involved in gemcitabine resistance of pancreatic cancer.

Gemcitabine has been a commonly used therapeutic agent for treatment of pancreatic cancer. In the clinic, agrowing resistance to gemcitabine has been observed in patients with pancreatic cancer, and investigation of the underlying mechanism of gemcitabine resistance is urgently required. The microRNA (miRNA)-producing enzyme, Dicer, is crucial for the maturation of miRNAs, andis involvedin clinical aggressiveness, poor prognosis, and survival outcomes in various cancers, however, the role of Dicer in acquired gemcitabine resistance of pancreatic cancer isstill not clear. Here, we found that Dicer expression was significantly increased in gemcitabine-resistant PANC-1 (PANC-1/GEM) cells compared with parental PANC-1 cells and observed a high level of Dicer correlated with increased risk of pancreatic cancer. Suppression of Dicer obviously decreased gemcitabine resistance in PANC-1/GEM cells; consistently, overexpression of Dicer in PANC-1 cells increased gemcitabine resistance. Moreover, we identified that transcriptional factor Sp1 targeted the promoter region of Dicer and found ERK/Sp1 signaling regulated Dicer expression in PANC-1/GEM cells, as well as positively correlated with pancreatic cancer progression and suggest that targeting the ERK/Sp1/Dicer pathway has potential therapeutic value for pancreatic cancer with acquired resistance to gemcitabine.

Abstract PO-062: EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1

Abstract Epithelial-mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a significant loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, basolateral membrane localization and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, basolateral localization and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed immunohistochemical analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface co-expression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT. Citation Format: Brenna Weadick, Debasis Nayak, Avinash K. Persaud, Sau Wai Hung, Radhika Raj, Wei Chen, Junan Li, Terence M. Williams, Rajgopal Govindarajan. EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1 [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-062.

The role of ferroptosis regulators in the prognosis, immune activity and gemcitabine resistance of pancreatic cancer.

BackgroundFerroptosis is a novel form of regulated cell death that can inhibit the progression of chemotherapy-resistant tumors. However, the types of cancer most susceptible to ferroptosis induction and the role of ferroptosis regulators in cancers, especially pancreatic cancer, remain unclear.MethodsRNA sequencing data of 31 cancers were collected from The Cancer Genome Atlas (TCGA) and The Genotype-Tissue Expression (GTEx). A nomogram integrating patients’ clinical information and risk scores based on the expression levels of ferroptosis regulators was depicted. Correlations among the activity levels of 29 immunity-associated gene sets, immune scores, infiltrating immune cells and key ferroptosis regulators were assessed.ResultsWe performed a pan-cancer analysis and identified 14 distinct cancers that may show a robust response to ferroptosis inducers. Interestingly, the Xc-complex, which is the major target of ferroptosis induction, was upregulated in gemcitabine-resistant pancreatic cancer cells (P<0.05). Furthermore, we focused on the role of ferroptosis regulators in mediating the survival of patients with pancreatic cancer and constructed a prognostic model with good accuracy (AUC =0.713). We also correlated elevated sensitivity to ferroptosis with higher scores for CD8+ T cells (P<0.001), the type two interferon response (P<0.001) and immune checkpoints (P<0.05).ConclusionsWe hypothesized that the ferroptosis pathway plays an important role in the prognosis of pancreatic cancer. Immuno- and chemotherapy combined with a ferroptosis inducer is a feasible therapeutic approach for pancreatic cancer.

MicroRNA-136-5p regulates gemcitabine resistance in pancreatic cancer via down-regulating ZNF32.

We explored the regulation of microRNA-136-5p on gemcitabine resistance of pancreatic cancer (PCa) and further highlighted the crosstalk between microRNA-136-5p and ZNF32, so as to provide an effective theoretical basis for target treatment of PCa. MicroRNA-136-5p and ZNF32 levels in tumor specimens of 48 patients with PCa were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) method, and the interplay between microRNA-136-5p and clinicopathological parameters, as well as prognosis of those patients was also analyzed. Meanwhile, in gemcitabine-resistant PCa cell lines PANC-1 and CFPAC-1, microRNA-136-5p overexpression model was constructed, and cell counting kit-8 (CCK-8), transwell, as well as cell wound healing assays were carried out to assess the impact of microRNA-136-5p on PCa cell functions. Finally, Luciferase assay and recovery experiments were conducted to specify the precise underlying mechanism. qRT-PCR results revealed a significant low expression of microRNA-136-5p both in tumor tissues of PCa patients and in PCa cell lines compared to the normal control groups. In addition, microRNA-136-5p mimics markedly attenuated the proliferation and migration abilities of the gemcitabine-resistant PCa cell lines. The Luciferase assay verified certain binding sites between microRNA-136-5p and ZNF32, while qPCR results indicated a negative correlation between the two in PCa tissues. Moreover, recovery experiments demonstrated that ZNF32 overexpression reversed the inhibitory effect on the malignant progression of gemcitabine-resistant PCa cells induced by microRNA-136-5p. MicroRNA-136-5p can reduce the proliferation rate and metastasis ability of PCa cells via regulating ZNF32, and thus alleviates gemcitabine resistance in PCa cells.

Emodin alleviates gemcitabine resistance in pancreatic cancer by inhibiting MDR1/P-glycoprotein and MRPs expression.

Gemcitabine is a gold standard chemotherapeutic agent for pancreatic cancer. However, gemcitabine has limited effectiveness due to the short-term development of chemoresistance. Emodin, a natural anthraquinone derivative isolated from the roots of rheumatic palm leaves prevents immunosuppression and exerts anticancer effects. The present study aimed to evaluate the effect of emodin on gemcitabine resistance. Gemcitabine-resistant PANC-1 pancreatic cancer cell xenografts were established in athymic mice, which were randomly assigned into four treatments groups as follows: Gemcitabine group, Emodin group, Gemcitabine+Emodin group and Negative control group. Body weight, tumor volume and tumor weight were measured over the course of treatment. The effect of each treatment on tumor tissue proliferation and apoptosis from nude mice was evaluated by using immunohistochemistry. The effect of each treatment on the proliferation of gemcitabine-resistant PANC-1 cells was also determined by using the Cell Counting Kit-8. Then, reverse transcription-quantitative (RT-q) PCR and western blotting were used to detect the mRNA and protein expression, respectively, of multidrug resistance gene 1 (MDR1) and the drug resistance-related proteins MRP1 and MRP5. The function and expression level of DR1 gene product, p-glycoprotein, was also analysed by flow cytometry and RT-qPCR, respectively. The results demonstrated that the combination of gemcitabine and emodin significantly reduced xenograft volume and reduced tumor growth in mice compared with treatment with gemcitabine or emodin only. In addition, emodin treatment reduced resistance to gemcitabine, which was characterized by the downregulation of P-glycoprotein, MRP1 and MRP5 expression in the group receiving combination treatment. The level of P-glycoprotein was also decreased in the group treated with gemcitabine+emodin compared with the single treatment groups. Taken together, these results demonstrated that emodin enhanced gemcitabine efficacy in tumor treatment and alleviated gemcitabine resistance in PANC-1 cell xenografts in mice via suppressing MDR1/P-glycoprotein and MRP expression.

High Expression of MUC15 Is Correlated with Poor Prognosis of Pancreatic Cancer and Promotes Migration, Invasion, and Chemo-Resistance In Vitro.

BackgroundMUC15, one of the hydrophilic glycoproteins that protect wet-surfaced epithelia, has been shown to be involved in tumorigenesis of various tumors. However, the mechanism of MUC15 in pancreatic cancer have not been revealed yet. Our study focused on investigating its clinical significance and function in pancreatic cancer.Material/MethodsUsing tissue microarrays and immunohistochemical staining, we evaluated MUC15 expression in 92 patients diagnosed with pancreatic ductal adenocarcinoma (PDAC). The correlations between MUC15 expression and clinicopathological variables and prognosis were analyzed. To validate our findings, we analyzed the data from an online database. We then demonstrated its function or mechanism in pancreatic cancer cell lines using transwell assay, cytotoxicity assay, cell apoptotic detection, and western blot.ResultsThe expression level of MUC15 was remarkably increased in PDAC tissues in comparison with para-cancerous tissues, and was associated with poor prognosis. Cytoplasmic MUC15 expression was identified as an independent prognostic indicator for overall survival by multivariate Cox regression analysis. Functionally, overexpressed MUC15 enhanced the migration and invasion ability in cancer cells. In vitro studies revealed that MUC15 enhanced the gemcitabine resistance of pancreatic cancer. Additionally, the regulatory mechanism of MUC15 in PDAC were correlated with ERK and AKT signaling pathways.ConclusionsWe performed integrated analysis and revealed that MUC15 is a good prognostic predictor for patients with PDAC. The functional experiments showed that MUC15 contributed to the malignant behaviors of pancreatic cancer in vitro.

Targeting the Microenvironment to Overcome Gemcitabine Resistance in Pancreatic Cancer.

Pancreatic cancer is characterized by an extensive and complex microenvironment, and is resistant to both chemotherapy and immune checkpoint blockade. The study by Principe and colleagues in this issue of Cancer Research proposes a combinatorial approach based on targeting the very mechanisms of resistance to gemcitabine, a commonly used chemotherapeutic agent. The authors show that gemcitabine treatment causes profound changes in the pancreatic cancer microenvironment, including elevated TGFβ signaling and immune checkpoint expression, as well as increased antigen presentation in tumor cells. Accordingly, they show that the combination of chemotherapy, TGFβ signaling inhibition, and immune checkpoint blockade effectively restores antitumor immunity and results in a significant survival benefit.See related article by Principe et al., p. 3101.

LncRNA PVT1 promotes gemcitabine resistance of pancreatic cancer via activating Wnt/\u03b2-catenin and autophagy pathway through modulating the miR-619-5p/Pygo2 and miR-619-5p/ATG14 axes

BackgroundPancreatic cancer is one of the most lethal malignancies and has an extremely poor diagnosis and prognosis. The development of resistance to gemcitabine is still a major challenge. The long noncoding RNA PVT1 was reported to be involved in carcinogenesis and chemoresistance; however, the mechanism by which PVT1 regulates the sensitivity of pancreatic cancer to gemcitabine remains poorly understood.MethodsThe viability of pancreatic cancer cells was assessed by MTT assay in vitro and xenograft tumor formation assay in vivo. The expression levels of PVT1 and miR-619-5p were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Western blotting analysis and qRT-PCR were performed to assess the protein and mRNA levels of Pygo2 and ATG14, respectively. Autophagy was explored via autophagic flux detection under confocal microscopy and autophagic vacuole investigation under transmission electron microscopy (TEM). The functional role and mechanism of PVT1 were further investigated by gain- and loss-of-function assays in vitro.ResultsIn the present study, we demonstrated that PVT1 was up-regulated in gemcitabine-resistant pancreatic cancer cell lines. Gain- and loss-of-function assays revealed that PVT1 impaired sensitivity to gemcitabine in vitro and in vivo. We further found that PVT1 up-regulated the expression of both Pygo2 and ATG14 and thus regulated Wnt/β-catenin signaling and autophagic activity to overcome gemcitabine resistance through sponging miR-619-5p. Moreover, we discovered three TCF/LEF binding elements (TBEs) in the promoter region of PVT1, and activation of Wnt/β-catenin signaling mediated by the up-regulation of Pygo2 increased PVT1 expression by direct binding to the TBE region. Furthermore, PVT1 was discovered to interact with ATG14, thus promoting assembly of the autophagy specific complex I (PtdIns3K-C1) and ATG14-dependent class III PtdIns3K activity.ConclusionsThese data indicate that PVT1 plays a critical role in the sensitivity of pancreatic cancer to gemcitabine and highlight its potential as a valuable target for pancreatic cancer therapy.

A G-quadruplex-binding compound shows potent activity in human gemcitabine-resistant pancreatic cancer cells

Gemcitabine is a drug of choice in the treatment of human pancreatic cancer. Chemo-resistance to this drug is common and has been attributed to a variety of distinct mechanisms, involving > 100 genes. A recently developed small-molecule G-quadruplex ligand, the trisubstituted naphthalene diimide compound CM03, has previously been shown to have equivalent potency to gemcitabine in the pancreatic cancer cell line MIA PaCa-2. We report here on cell lines of increased resistance to gemcitabine that have been generated from this line, with the most resistant having 1,000-fold reduced sensitivity to gemcitabine. These resistant lines retain nM sensitivity to CM03. The molecular basis for the retention of potency by this G-quadruplex ligand has been examined using whole transcriptome data analysis with RNA-seq. This has revealed that the pattern of pathways down regulated by CM03 in the parental MIA PaCa-2 cell line is largely unaffected in the gemcitabine-resistant line. The analysis has also shown that the expression patterns of numerous genes involved in gemcitabine sensitivity are down regulated in the resistant line upon CM03 treatment. These results are supportive of the concept that G-quadruplex small molecules such as CM03 have potential for clinical use in the treatment of gemcitabine-resistant human pancreatic cancer.

Activating miRNA-mRNA network in gemcitabine-resistant pancreatic cancer cell associates with alteration of memory CD4+ T cells.

BackgroundTo identify key microRNAs (miRNAs) and their target mRNAs related to gemcitabine-resistant pancreatic cancer (PC) and investigate the association between gemcitabine-resistant-related miRNAs and mRNAs and immune infiltration.MethodsExpression profiles of miRNAs and mRNAs were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed miRNAs and mRNAs (referred to as “DEmiRNAs” and “DEmRNAs”, respectively) were distinguished between gemcitabine-resistant PC cells and its parental cells. The DEmRNAs targeted by the DEmiRNAs were retrieved using miRDB, microT, and Targetscan. Furthermore, GO and KEGG pathway enrichment analysis and GSEA were performed. The Kaplan-Meier plotter was used to analyze the prognosis of key DEmiRNAs and DEmRNAs on PC patients. The relationship between the key DEmRNAs and tumor-infiltrating immune cells in PC was investigated using CIBERSORT method using the LM22 signature as reference. Key infiltrating immune cells were further analyzed for the associations with prognosis of TCGA PAAD patients.ResultsFour DEmiRNAs, including hsa-miR-3178, hsa-miR-485-3p, hsa-miR-574-5p, and hsa-miR-584-5p, were identified to target seven DEmRNAs, including MSI2, TEAD1, GNPDA1, RND3, PRKACB, TRIM68, and YKT6, individually, in gemcitabine-resistant PC cells versus parental cells. Gemcitabine-resistant PC cells were enriched in proteasome-related, immune-related, and memory CD4+ T cell-related pathways, indicating a gemcitabine therapeutic effect on PC cells. All four DEmiRNAs and almost all DEmRNAs had an impact on the prognosis of PC patients. All seven DEmRNAs had remarkable effects on CD4+ memory T cells, which were affected by the gemcitabine therapeutic effect. Effector memory CD4+ T cells rather than central memory CD4+ T cells predicted a good prognosis according to the TCGA PAAD dataset.ConclusionsGemcitabine resistance can alter the fraction of memory CD4+ T cells via hsa-miR-3178, hsa-miR-485-3p, hsa-miR-574-5p and hsa-miR-584-5p targeted MSI2, TEAD1, GNPDA1, RND3, PRKACB, TRIM68, and YKT6 network in PC.

Activation of GLP-1 receptor enhances the chemosensitivity of pancreatic cancer cells.

This study aimed to determine whether and how the glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide affects the chemoresistance and chemosensitivity of pancreatic cancer cells to gemcitabine in vitro and in vivo. The GLP-1R and protein kinase A (PKA) levels were compared between the human pancreatic cancer cell line PANC-1 and the gemcitabine-resistant cell line PANC-GR. The in vitro effects of liraglutide on the cell proliferation and apoptosis as well as the nuclear factor-kappa B NF-κB expression levels of PANC-GR cells were evaluated. In addition, a mouse xenograft model of human pancreatic cancer was established by s.c. injection of PANC-1 cells, and the effects of liraglutide on the chemosensitivity were evaluated in vitro and in vivo. In contrast to PANC-1 cells, PANC-GR cells exhibited lower expression levels of GLP-1R and PKA. Incubation with liraglutide dose dependently inhibited the growth, promoted the apoptosis, and increased the expression of GLP-1R and PKA of PANC-GR cells. Similar effects of liraglutide were observed in another human pancreatic cancer cell line MiaPaCa-2/MiaPaCa-2-GR. Either the GLP-1R antagonist Ex-9, the PKA inhibitor H89, or the NF-κB activator lipopolysaccharide (LPS) could abolish the antiproliferative and proapoptotic activities of liraglutide. Additionally, each of these agents could reverse the expression of NF-κB and ABCG2, which was decreased by liraglutide treatment. Furthermore, liraglutide treatment increased the chemosensitivity of pancreatic cancer cells to gemcitabine, as evidenced by in vitro and in vivo experiments. Thus, GLP-1R agonists are safe and beneficial for patients complicated with pancreatic cancer and diabetes, especially for gemcitabine-resistant pancreatic cancer.

Imidazo[2,1-b] [1,3,4]thiadiazoles with antiproliferative activity against primary and gemcitabine-resistant pancreatic cancer cells

A new series of eighteen imidazo [2,1-b] [1,3,4]thiadiazole derivatives was efficiently synthesized and screened for antiproliferative activity against the National Cancer Institute (NCI-60) cell lines panel. Two out of eighteen derivatives, compounds 12a and 12h, showed remarkably cytotoxic activity with the half maximal inhibitory concentration values (IC50) ranging from 0.23 to 11.4 μM, and 0.29–12.2 μM, respectively. However, two additional compounds, 12b and 13g, displayed remarkable in vitro antiproliferative activity against pancreatic ductal adenocarcinoma (PDAC) cell lines, including immortalized (SUIT-2, Capan-1, Panc-1), primary (PDAC-3) and gemcitabine-resistant (Panc-1R), eliciting IC50 values ranging from micromolar to sub-micromolar level, associated with significant reduction of cell-migration and spheroid shrinkage. These remarkable results might be explained by modulation of key regulators of epithelial-to-mesenchymal transition (EMT), including E-cadherin and vimentin, and inhibition of metalloproteinase-2/-9. High-throughput arrays revealed a significant inhibition of the phosphorylation of 45 tyrosine kinases substrates, whose visualization on Cytoscape highlighted PTK2/FAK as an important hub. Inhibition of phosphorylation of PTK2/FAK was validated as one of the possible mechanisms of action, using a specific ELISA. In conclusion, novel imidazothiadiazoles show potent antiproliferative activity, mediated by modulation of EMT and PTK2/FAK.

Effect of microRNA-762 on the drug resistance to gemcitabine of pancreatic cancer PANC-1 cell line

Objective To explore the effect of microRNA (miRNA, miR)-762 on the drug resistance to gemcitabine (GEM) of pancreatic cancer PANC-1 cells. Methods Real-time quantitative polymerase chain reaction (Real-time PCR) was used to detect the expression of miR-762 mRNA in gemcitabine-resistant pancreatic cancer cell line PANC-1/GEM and the non-drug-resistant cell line PANC-1 of pancreatic cancer. The miR-762 mimics, miR-762 inhibitors and scramble sequences were transfected into PANC-1/GEM cells respectively with Lipofectamine™ 2000. The proliferation and the drug sensitivity of PANC-1/GEM cells to GEM were measured by cell counting kit-8 (CCK-8) assay. The apoptosis of PANC-1/GEM cells was examined by flow cytometry. The expression of apoptosis related proteins was detected by Western blotting. Results The miR-762 expression was significantly up-regulated in PANC-1/GEM cells (2.88±0.37) compared to that in PANC-1 cells (1.22±0.32) (t=7.340, P<0.01), and the difference is statistically significant. The miR-762 mRNA expression in PANC-1/GEM cells were obviously increased after transfection with miR-762 mimics in mimics group (4.96±0.67) as compared with negative control group (2.87±0.45) (t=-4.920, P<0.01), but markedly decreased after transfection with miR-762 inhibitors in mimics group (0.72±0.18) as compared with negative control group (2.87±0.45) (t=8.430, P<0.01). Meanwhile, A450, half maximal inhibitory concentration (IC50) and B cell lymphoma/leukemia-2 (bcl-2), phosphorylated protein kinase B (p-Akt) and phosphorylated glycogen synthase kinase 3β (p-GSK-3β) protein expression in miR-762 mimics group were significantly higher than those in negative control group after transfection, and apoptosis rate and bcl-2 associated X protein (bax) protein expression were significantly lower than those in negative control group after transfection. While A450, IC50 and bcl-2, p-Akt and p-GSK-3β protein expression in miR-762 inhibitors group were significantly lower than those in negative control group after transfection, and apoptosis rate and bax protein expression were significantly higher than those in negative control group after transfection (P<0.01). Conclusion The expression of miR-762 is up-regulated in pancreatic cancer drug resistant cells and can induce the cell proliferation and inhibit cell apoptosis in PANC-1/GEM cells, thus reducing the sensitivity of PANC-1/GEM cells to GEM, which may be associated with the inhibition of pro-apoptotic factor bax expression and the promotion of bcl-2, p-Akt and p-GSK-3β expression. Key words: Pancreatic cancer; MicroRNA-762; Gemcitabine; Chemoresistance