SILAC-Based Quantitative Proteomics Identifies Multifactorial Mechanism of Oxaliplatin Resistance in Pancreatic Cancer Cells

Oxaliplatin is a commonly used chemotherapeutic drug for the treatment of pancreatic cancer. Understanding the cellular mechanisms of oxaliplatin resistance is important for developing new strategies to overcome drug resistance in pancreatic cancer. In this study, we performed a stable isotope labelling by amino acids in cell culture (SILAC)-based quantitative proteomic analysis of oxaliplatin-resistant and sensitive pancreatic cancer PANC-1 cells. We identified 107 proteins whose expression levels changed between oxaliplatin-resistant and sensitive cells, which were involved in multiple biological processes, including DNA repair, drug response, apoptotic signalling, and the type 1 interferon signalling pathway. Notably, myristoylated alanine-rich C-kinase substrate (MARCKS) and wntless homolog protein (WLS) were upregulated in oxaliplatin-resistant cells compared to sensitive cells, as confirmed by qRT-PCR and Western blot analysis. We further demonstrated the activation of AKT and {beta}-catenin signalling (downstream targets of MARCKS and WLS, respectively) in oxaliplatin-resistant PANC-1 cells. Additionally, we show that the siRNA-mediated suppression of both MARCKS and WLS enhanced oxaliplatin sensitivity in oxaliplatin-resistant PANC-1 cells. Taken together, our results provide insights into multiple mechanisms of oxaliplatin resistance in pancreatic cancer cells and reveal that MARCKS and WLS might be involved in the chemotherapeutic resistance in pancreatic cancer.