The present application demonstrates that Salinosporamide A can be used to sensitize cancer cells to cancer therapy. Furthermore, the present application demonstrates that Salinosporamide A acts as a therapeutic agent to kill or inhibit cancer cells after sensitization of the cells by an antibody or other chemosensitizing reagents. The cancer cells can be either therapy-sensitive or therapy resistant. The present application further demonstrates that Salinosporamide A induces the expression of Raf kinase inhibitor protein (RKIP) and PTEN, tumor suppressor proteins, and inhibits the expression of YY1, a transcriptional regulator protein overexpressed in cancer cells and also inhibits the growth factor pleiotrophin (PTN).
