2‐D PAGE‐based comparison of proteasome inhibitor bortezomib in sensitive and resistant mantle cell lymphoma

Abstract

Although gene expression following bortezomib treatment has been previously explored, direct effects of bortezomib-induced proteasome inhibition on protein level has not been analyzed so far. Using 2-D PAGE in five mantle cell lymphoma cell lines, we screened for cellular protein level alterations following treatment with 25 nM bortezomib for up to 4 h. Using MS, we identified 38 of the 41 most prominent reliably detected protein spots. Twenty-one were affected in all cell lines, whereas the remaining 20 protein spots were exclusively altered in sensitive cell lines. Western blot analysis was performed for 17 of the 38 identified proteins and 70.6% of the observed protein level alterations in 2-D gels was verified. All cell lines exhibited alterations of the cellular protein levels of heat shock-induced protein species (HSPA9, HSP7C, HSPA5, HSPD1), whereas sensitive cell lines also displayed altered cellular protein levels of energy metabolism (ATP5B, AK5, TPI1, ENO-1, ALDOC, GAPDH), RNA and transcriptional regulation (HNRPL, SFRS12) and cell division (NEBL, ACTB, SMC1A, C20orf23) as well as tumor suppressor genes (ENO-1, FH). These proteins clustered in a tight interaction network centered on the major cellular checkpoints TP53. The results were confirmed in primary mantle cell lymphoma, thus confirming the critical role of these candidate proteins of proteasome inhibition.

Quantitative proteomic analysis to decipher the differential apoptotic response of bortezomib‐treated APL cells before and after retinoic acid differentiation reveals involvement of protein toxicity mechanisms

“…The inducible heat‐shock 70 kDa protein 1A/1B (HSP71) and the heat shock 90 kDa protein A (HS90A) are upregulated upon BZ treatment in NB4 cells as previously described in other cellular models but at a lesser extent for HSP71 or not at all for HS90A in differentiated NB4 cells. These changes likely reflect a stress response in agreement with the recognized role of the chaperone proteins in the protection of cells against therapeutic agents.…”

The Hsp90 inhibitor IPI-504 overcomes bortezomib resistance in mantle cell lymphoma in vitro and in vivo by down-regulation of the prosurvival ER chaperone BiP/Grp78

“…11 Exactly how the misfolded proteins are shuttled to the proteasome remains unclear but may involve discrete structures known as aggresomes and molecular chaperones of the Hsp70 family. 33,34 Accordingly, deregulated expression of several Hsp70 family members is associated with bortezomib resistance in a wide range of B-cell malignancies, including MCL, 25 multiple myeloma (MM), 35 and diffuse large B-cell lymphoma, 36 and it may alter the response of cyclin D1-overexpressing B cells to chemotherapeutic agents. 37 In the present work, we developed 2 MCL-derived cell lines with acquired resistance to bortezomib, showing no defect in proteasome activity or apoptosis machinery, but presenting altered levels of the ER Hsp70 homolog BiP/Grp78 after bortezomib treatment.…”

“…25,26 Therefore, we analyzed the expression of Hsp90, its co-chaperones, Hsp70 and Hsp27, and the UPR components BiP/Grp78 and phospho-eIF2␣ in Jeko-1, JBR, Z-138, and ZBR cells. After bortezomib treatment, BiP/Grp78 was the only upregulated chaperone in JBR and ZBR cells, compared with their parental cell lines ( Figure 1D).…”

Suppression of fructose‐bisphosphate aldolase C expression as a predictor of advanced oral squamous cell carcinoma

“…18,19 Moreover, ALDOC was altered specifically in bortezomib-induced apoptosis cells and may be an apparent target for molecular-targeted therapies. 20 ALDOC is believed to play nonglycolytic roles and may be involved in cancer progression. However, the critical roles and underlying mechanism of ALDOC in human oral cancer are unknown.…”