Background: Pancreatic cancer is unresectable in over 80% patients owing to difficulty in early diagnosis. Chemotherapy is the most frequently adopted therapy for advanced pancreatic cancer. The development of drug resistance to gemcitabine, which is always used in standard chemotherapy, often results in therapeutic failure. However, the molecular mechanisms underlying the gemcitabine resistance remain unclear.
Aim: This study sought to explore the microRNA-mRNA network that is associated with the development of gemcitabine resistance and to identify molecular targets for overcoming the gemcitabine resistance.
Method: A gemcitabine-resistant cell line (SW1990/GEM) was established by exposing SW1990 pancreatic cancer cells to long-term gemcitabine with increasing concentrations. The mRNA and microRNA expression profiles of SW1990 cells and SW1990/GEM cells were determined using RNA-seq analysis. The expression profiles of selected genes and microRNAs were confirmed by using Q-PCR assays. The differential mRNAs and microRNAs were identified, the microRNA -target regulation information was integrated, and a microRNA–mRNA regulatory network associated with gemcitabine resistance development in pancreatic cancer cells was constructed.
Results: SW1990/GEM was established with a high IC50 (the concentration needed for 50% growth inhibition, 847.23 μM). By comparing the results in control SW1990 cells, 507 upregulated genes and 550 downregulated genes in SW1990/GEM cells were identified as differentially expressed genes correlated with gemcitabine sensitivity. The upregulated genes were mainly associated with drug response and apoptosis, and the downregulated genes were correlated with cell cycle progression and RNA splicing. Furthermore, combining the differentially expressed microRNAs and mRNAs as well as the predicted targets for these microRNAs, a core microRNA-mRNA regulatory network was constructed.
Conclusions: A differential gene and microRNA expression pattern was constructed in gemcitabine resistant pancreatic cancer cells, which may be useful for the detection and treatment of drug resistance in pancreatic cancer patients.