Protein disulfide isomerase: a promising target for cancer therapy

Protein disulfide isomerase (PDI) has a key role in maintaining cellular homeostasis by mediating oxidative protein folding. It catalyzes disulfide bond formation, breakage and rearrangement in the endoplasmic reticulum and has chaperone protein activity. Increasing evidence suggests that PDI supports the survival and progression of several cancers. During the past decade, robust PDI activity assays have been developed and several PDI inhibitors identified, but none has been approved for clinical use. Herein, we review current knowledge of the role of PDI in cancer and discuss various assays for measuring the activities of PDI, highlighting their sensitivities and usefulness for high-throughput screening. The previously reported PDI inhibitors require further validation to serve as bona fide leads and additional optimization to generate novel drug candidates for clinical studies.