Establishment of gemcitabine-resistant human pancreatic cancer cells and effect of brefeldin-a on the resistant cell line

Unravelling the complexities of resistance mechanism in pancreatic cancer: insights from in vitro and ex-vivo model systems

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor prognosis and rising global deaths. Late diagnosis, due to absent early symptoms and biomarkers, limits treatment mainly to chemotherapy, which soon encounters resistance. PDAC treatment innovation is hampered by its complex and heterogeneous resistant nature, including mutations in key genes and a stromal-rich, immunosuppressive tumour microenvironment. Recent studies on PDAC resistance stress the need for suitable in vitro and ex vivo models to replicate its complex molecular and microenvironmental landscape. This review summarises advances in these models, which can aid in combating chemoresistance and serve as platforms for discovering new therapeutics. Immortalised cell lines offer homogeneity, unlimited proliferation, and reproducibility, but while many gemcitabine-resistant PDAC cell lines exist, fewer models are available for resistance to other drugs. Organoids from PDAC patients show promise in mimicking tumour heterogeneity and chemosensitivity. Bioreactors, co-culture systems and organotypic slices, incorporating stromal and immune cells, are being developed to understand tumour-stroma interactions and the tumour microenvironment's role in drug resistance. Lastly, another innovative approach is three-dimensional bioprinting, which creates tissue-like structures resembling PDAC architecture, allowing for drug screening. These advanced models can guide researchers in selecting optimal in vitro tests, potentially improving therapeutic strategies and patient outcomes.

Proteomics and Bioinformatics Identify Drug-Resistant-Related Genes with Prognostic Potential in Cholangiocarcinoma

Drug resistance is a major challenge in the treatment of advanced cholangiocarcinoma (CCA). Understanding the mechanisms of drug resistance can aid in identifying novel prognostic biomarkers and therapeutic targets to improve treatment efficacy. This study established 5-fluorouracil- (5-FU) and gemcitabine-resistant CCA cell lines, KKU-213FR and KKU-213GR, and utilized comparative proteomics to identify differentially expressed proteins in drug-resistant cells compared to parental cells. Additionally, bioinformatics analyses were conducted to explore the biological and clinical significance of key proteins. The drug-resistant phenotypes of KKU-213FR and KKU-213GR cell lines were confirmed. In addition, these cells demonstrated increased migration and invasion abilities. Proteomics analysis identified 81 differentially expressed proteins in drug-resistant cells, primarily related to binding functions, biological regulation, and metabolic processes. Protein-protein interaction analysis revealed a highly interconnected network involving MET, LAMB1, ITGA3, NOTCH2, CDH2, and NDRG1. siRNA-mediated knockdown of these genes in drug-resistant cell lines attenuated cell migration and cell invasion abilities and increased sensitivity to 5-FU and gemcitabine. The mRNA expression of these genes is upregulated in CCA patient samples and is associated with poor prognosis in gastrointestinal cancers. Furthermore, the functions of these proteins are closely related to the epithelial-mesenchymal transition (EMT) pathway. These findings elucidate the potential molecular mechanisms underlying drug resistance and tumor progression in CCA, providing insights into potential therapeutic targets.

Biodegradable gemcitabine-loaded microdevice with sustained local drug delivery and improved tumor recurrence inhibition abilities for postoperative pancreatic tumor treatment

At present, the 10-year survival rate of patients with pancreatic cancer is still less than 4%, mainly due to the high cancer recurrence rate caused by incomplete surgery and lack of effective postoperative adjuvant treatment. Systemic chemotherapy remains the only choice for patients after surgery; however, it is accompanied by off-target effects and server systemic toxicity. Herein, we proposed a biodegradable microdevice for local sustained drug delivery and postoperative pancreatic cancer treatment as an alternative and safe option. Biodegradable poly(l-lactic-co-glycolic acid) (P(L)LGA) was developed as the matrix material, gemcitabine hydrochloride (GEM·HCl) was chosen as the therapeutic drug and polyethylene glycol (PEG) was employed as the drug release-controlled regulator. Through adjusting the amount and molecular weight of PEG, the controllable degradation of matrix and the sustained release of GEM·HCl were obtained, thus overcoming the unstable drug release properties of traditional microdevices. The drug release mechanism of microdevice and the regulating action of PEG were studied in detail. More importantly, in the treatment of the postoperative recurrence model of subcutaneous pancreatic tumor in mice, the microdevice showed effective inhibition of postoperative in situ recurrences of pancreatic tumors with excellent biosafety and minimum systemic toxicity. The microdevice developed in this study provides an option for postoperative adjuvant pancreatic treatment, and greatly broadens the application prospects of traditional chemotherapy drugs.

Sex Determining Region Y Box 9 Induces Chemoresistance in Pancreatic Cancer Cells by Induction of Putative Cancer Stem Cell Characteristics and Its High Expression Predicts Poor Prognosis

OBJECTIVES

Pancreatic cancer is a highly chemoresistant tumor and underlying mechanisms are not well understood. Sex determining region Y box 9 (Sox9) is a transcription factor playing important roles on maintenance of pluripotent cells during pancreatic organogenesis. The purpose of this study is to evaluate the roles of Sox9 in pancreatic cancer.

METHODS

The Sox9 expression was evaluated by immunohistochemical analysis. Effects of Sox9 inhibition by siRNA or shRNA on chemosensitivity, sphere formation, stem cell markers expression, and in vivo tumor formation rate were examined using pancreatic cancer cell lines.

RESULTS

High expression of Sox9 in pancreatic cancer tissue is correlated with poor prognosis (P = 0.011). Cells with high Sox9 expression (PANC-1, Capan-1) showed stronger chemoresistance to Gemcitabine than cells with low Sox9 expression (BxPC-3, MIA PaCa-2). The chemosensitivity in PANC-1 was recovered by suppressing Sox9 using siRNA (P < 0.05). Both sphere formation rate and the proportion of CD44CD24 cells were decreased by Sox9 inhibition. Tumor formation rate of Tet-on inducible Sox9 shRNA-transfected PANC-1 cells in KSN/Slc nude mice was decreased by induction of shRNA with doxycycline feeding (P < 0.05).

CONCLUSION

Sox9 plays an important role in chemoresistance by the induction of stemness in pancreatic cancer cells.

Effect of brefeldin A and castanospermine on resistant cell lines as supplements in anticancer therapy

In the present study, we analyzed the influence of brefeldin A (BFA) and castanospermine (CAS) on the activity, stability and localization of P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) in various resistant cell lines. The impact of BFA and CAS on cell viability was assessed using the MTT test. Western blotting (WB) was performed to assess the effect of the inhibitors on the expression of the investigated proteins. Immunofluorescence was employed to assess the effect of BFA and CAS on the cellular localization of the proteins. Flow cytometry was used to verify the functional role of inhibitors on drug uptake and efflux. The MTT test showed that BFA had a significant effect on cell viability in LoVo/Dx and W1PR cell lines. WB analysis demonstrated that BFA partially blocked Pgp N-glycosylation and induced BCRP degradation and CASP 3-dependent apoptosis in W1TR cells; however, the BFA activity was p53-independent. CAS had no effect on the stability of Pgp but increased the level of non-glycosylated BCRP. The expression of p53 protein decreased in all of the cells that were treated with CAS. Immunofluorescence revealed that BFA caused a more granular Pgp signal in W1PR and BCRP in A2780T1 cells. Furthermore, BFA caused morphological changes in LoVo/Dx and W1TR cell lines. CAS also induced a granular signal in all of the cell lines, except W1TR. The flow cytometry showed higher dye accumulation in sensitive cell lines. We observed an increase in the mean fluorescence intensity (MFI) of Rho123 in LoVo/Dx cells treated with BFA and CAS, but no differences were observed in W1PR. BFA had no effect on the MFI of W1TR, but CAS led to an increase in the level of intracellular H33342 in W1TR and A2780T1 cells. These results suggest that these compounds are likely to be useful as supplements in anticancer therapy.

Establishment of human pancreatic cancer gemcitabine‑resistant cell line with ribonucleotide reductase overexpression

A gemcitabine (GEM)-resistant human pancreatic cancer cell line (PANC-1RG7) was established in vitro by gradually increasing GEM concentrations and cloning cell cultures to develop a cellular model of acquired drug resistance studies. We found that PANC-1RG7 cells exhibited significantly different morphological characteristics from parental cells. PANC-1RG7 cells grew slowly (p<0.05), yet the cell cycle remained unchanged (p>0.05). PANC-1RG7, with a resistance index to GEM of 39.9, showed cross-resistance characteristics to methotrexate, gefitinib, cisplatin and 5-fluorouracil. The proliferation inhibition of GEM was significantly reduced in vivo (p<0.05). The known resistance-associated genes and proteins we detected remained unchanged, with the exception of cytidine deaminase, multidrug resistance-related protein and breast cancer resistance protein genes, which decreased; by contrast, 5'-nucleotidase, ribonucleotide reductase (RRM) 1 and RRM2 proteins increased (p<0.05). Therefore, a cell line with acquired GEM resistance was established successfully. Resistance was acquired by overexpressing RRM1 and RRM2 proteins.

Akt/mTOR signaling pathway is crucial for gemcitabine resistance induced by Annexin II in pancreatic cancer cells

BACKGROUND

Although gemcitabine has been widely used as a first-line chemo reagent for patients with pancreatic cancer, the response rate remains low. We previously identified Annexin II as a factor involved in gemcitabine resistance against pancreatic cancer. The aims of this study were to elucidate the signaling mechanism by which Annexin II induces gemcitabine resistance and to develop a new therapy that overcomes the resistance against gemcitabine.

METHODS

We compared the specific profiles of 12 targeted phosphorylated (p-) signaling proteins in gemcitabine-resistant (GEM-) and its wild-type pancreatic cancer cell lines (MIA PaCa-2) using the Bio-Plex assay system. We also evaluated the expression levels of Annexin II and two phosphoproteins, which showed different expressions in these two cell lines, by immunohistochemistry.

RESULTS

Annexin II overexpression was significantly associated with rapid recurrence after gemcitabine-adjuvant chemotherapy in patients with resected pancreatic cancer (P < 0.05). Bio-Plex analysis showed up-regulation of p-Akt in GEM-MIA PaCa-2 cells in which Annexin II is highly expressed. The expression level of p-Akt was significantly correlated with that of the downstream protein, p-mTOR, in pancreatic cancer tissues. Inhibition of mTOR phosphorylation canceled gemcitabine resistance in GEM-MIA PaCa-2 cells.

CONCLUSIONS

The Akt/mTOR pathway is involved in mechanisms of gemcitabine resistance induced by Annexin II in pancreatic cancer cells. This indicates that combination therapy with the mTOR inhibitor may overcome gemcitabine resistance. Annexin II as an indicator for selection of gemcitabine resistance could thus be applied to the development of novel tailor-made approaches for pancreatic cancer treatment.

Genexol inhibits primary tumour growth and metastases in gemcitabine-resistant pancreatic ductal adenocarcinoma

INTRODUCTION

Gemcitabine, the current standard of care for pancreatic ductal adenocarcinoma (PDA), has a less than 10% partial response rate. Genexol-PM, a modified form of paclitaxel, has been shown to have antitumour effects in clinical trials of metastatic breast and small-lung-cell carcinoma. The aim of the present study was to determine if Genexol would be a beneficial treatment for gemcitabine-resistant PDA.

MATERIALS AND METHODS

We measured the in vitro IC50s of gemcitabine and genexol in cell lines sensitive and resistant to gemcitabine. In vivo, animals with orthotopic pancreatic tumours, resistant to gemcitabine, were treated with phosphate-buffered saline (PBS), gemcitabine, Genexol or gemcitabine+Genexol. Tumour progression was monitored using red fluorescent protein imaging.

RESULTS

We showed equivalent IC50s for gemcitabine-sensitive and gemcitabine-resistant cell lines when treated with genexol. In vivo treatment with genexol resulted in a greater per cent reduction in tumour size, less metastatic spread and longer survival compared with treatment with gemcitabine.

DISCUSSION

Genexol proved to be an effective treatment for gemcitabine-resistant PDA. These data combined with the successful clinical use of genexol in Phase II trials of other malignancies suggests it maybe an effective treatment for pancreatic cancer, specifically for those patients resistant to gemcitabine.

Disulfiram/copper complex inhibiting NFkappaB activity and potentiating cytotoxic effect of gemcitabine on colon and breast cancer cell lines

Most of the gemcitabine (dFdC) resistant cell lines manifested high NFkappaB activity. The NFkappaB activity can be induced by dFdC and 5-FU exposure. The chemosensitizing effect of disulfiram (DS), an anti-alcoholism drug and NFkappaB inhibitor, and copper (Cu) on the chemoresistant cell lines was examined. The DS/Cu complex significantly enhanced the cytotoxicity of dFdC (resistant cells: 12.2-1085-fold) and completely reversed the dFdC resistance in the resitant cell lines. The dFdC-induced NFkappaB activity was markedly inhibited by DS/Cu complex. The data from this study indicated that DS may be used in clinic to improve the therapeutic effect of dFdC in breast and colon cancer patients.

Annexin II overexpression predicts rapid recurrence after surgery in pancreatic cancer patients undergoing gemcitabine-adjuvant chemotherapy

BACKGROUND

Gemcitabine has been shown to exhibit significant clinical activity against pancreatic cancer and has become a first-line chemotherapeutic for this disease in recent years. However, there are still many patients who do not respond to this treatment and it is expected to improve the clinical outcome if we can develop a method to predict the efficacy of gemcitabine before treatment. The purpose of this study was to determine novel factors that make pancreatic cancer resistant to gemcitabine.

MATERIALS AND METHODS

Using the high-resolution proteomic approach, agarose two-dimensional gel electrophoresis, we compared protein profiling of a gemcitabine-resistant pancreatic cancer cell line with its wild-type.

RESULTS

We identified Annexin II as an up-regulated protein in the gemcitabine-resistant pancreatic cancer cell line. Immunohistochemistry demonstrated that Annexin II was mainly expressed at the cell surface of pancreatic cancer cells. Interestingly, Annexin II overexpression in cancer cells was significantly associated with rapid recurrence after gemcitabine adjuvant chemotherapy in postoperative patients (P = .0078), and its staining was also an independent prognostic indicator of recurrence in pancreatic cancer patients who underwent adjuvant gemcitabine treatment after curative surgery on multivariate analysis (P = .0047). In addition, inhibition of Annexin II expression by siRNA in pancreatic cancer cell lines increased the cytotoxic efficacy of gemcitabine. These results indicate that Annexin II overexpression may induce gemcitabine resistance in pancreatic cancer resulting in rapid recurrence.

CONCLUSIONS

Analysis of Annexin II expression in cancer tissues may predict the clinical outcome of gemcitabine treatment, leading to the development of a new method for tailor-made treatment for this disease.

Treatment with an oral fluoropyrimidine, S-1, plus cisplatin in patients who failed postoperative gemcitabine treatment for pancreatic cancer: a pilot study

BACKGROUND

This study set out to evaluate, in patients with gemcitabine-resistant pancreatic cancer, the response rate and toxicity of S-1 plus cisplatin (CDDP).

METHODS

Seventeen patients with histologically diagnosed invasive ductal pancreatic cancer were enrolled in this study. All patients had growing recurrent pancreas cancer despite the administration of gemcitabine. Thirteen patients underwent pancreatectomy, and 2 underwent choledochojejunostomy and gastrojejunostomy without pancreatectomy. S-1 (80 mg/m(2) per day) was orally administered for 21 consecutive days, followed by a 14-day rest period. CDDP (40 mg/m(2)) in 500 ml saline was administered by intravenous drip on day 8. This schedule was repeated every 5 weeks until the occurrence of disease progression, unacceptable toxicities, or the patient's refusal to continue.

RESULTS

Five (29.4%) patients achieved a partial response and 2 (11.8%) had stable disease. In 5 of 15 patients (33.3%) who had elevated serum carbohydrate antigen (CA)19-9 levels at the start of treatment the CA19-9 was reduced by more than 50%. The median survival time was 10 months (range, 20 months), with 63.7% and 31.9% of patients alive at 6 and 12 months, respectively. Major adverse reactions in the 15 patients included gastrointestinal toxicities of grade 1 or 2. Only one patient (5.9%) developed grade 3 leucopenia.

CONCLUSION

S-1 with CDDP has a promising effect against gemcitabine-resistant pancreatic cancer, with easily manageable toxicities. Further investigation of this regimen is warranted in patients with pancreatic cancer, especially in comparison with gemcitabine.