Comparison of anti-cancer effects of novel protein disulphide isomerase (PDI) inhibitors in breast cancer cells characterized by high and low PDIA17 expression.

BACKGROUND: Protein disulphide isomerases (PDIs) play an important role in cancer progression. However, the relative contribution of the various isoforms of PDI in tumorigenesis is not clear. METHODS: The content of PDI isoforms in 22 cancer cells lines was investigated using LC-MS/MS-based proteomic analysis. The effects of PDIA1, PDIA3 and PDIA17 inhibition on the proliferation, migration and adhesion of MCF-7 and MDA-MB-231 cells, identified as high and low PDIA17 expressing cells, respectively, were assessed using novel aromatic N-sulphonamides of aziridine-2-carboxylic acid derivatives as PDI inhibitors. RESULTS: PDIA1 and PDIA3 were the most abundant in cancer cell lysates and were also detected extracellularly in breast cancer cells (MDA-MB-231 and MCF-7). Some cancer cell lines (e.g., MCF-7, HT-29) showed upregulated expression of PDIA17, whereas in others (e.g., MDA-MB-231, 67NR), PDIA17 was not detected. The simultaneous inhibition of PDIA1 and PDIA3 showed similar anti-proliferative effects in MCF-7 and MDA-MB-231 breast cancer cells. However, the inhibition of PDIA1 and PDIA17 in the MCF-7 cell line resulted in more effective anti-adhesive and anti-proliferative effects. CONCLUSIONS: PDIA1 and PDIA3 represent major isoforms of multiple cancer cells, and their non-selective inhibition displays significant anti-proliferative effects irrespective of whether or not PDIA17 is present. The more pronounced anti-adhesive effects of PDI inhibition in hormone-sensitive MCF-7 cells featured by higher levels of PDIs when compared to triple-negative MDA-MB-231 cells suggests that targeting extracellular PDIA1 and PDIA3 with or without additional PDIA17 inhibition may represent a strategy for personalized anti-adhesive, anti-metastatic therapy in cancers with high PDI expression.