Determinants of Sensitivity to DZNep Induced Apoptosis in Multiple Myeloma Cells

Abstract

The 3-Deazaneplanocin A (DZNep), one of S-adenosylhomocysteine (AdoHcy) hydrolase inhibitors, has shown antitumor activities in a broad range of solid tumors and acute myeloid leukemia. Here, we examined its effects on multiple myeloma (MM) cells and found that, at 500 nM, it potently inhibited growth and induced apoptosis in 2 of 8 MM cell lines. RNA from un-treated and DZNep treated cells was profiled by Affymetrix HG-U133 Plus 2.0 microarray and genes with a significant change in gene expression were determined by significance analysis of microarray (SAM) testing. ALOX5 was the most down-regulated gene (5.8-fold) in sensitive cells and was expressed at low level in resistant cells. The results were corroborated by quantitative RT-PCR. Western-blot analysis indicated ALOX5 was highly expressed only in sensitive cell line H929 and greatly decreased upon DZNep treatment. Ectopic expression of ALOX5 reduced sensitivity to DZNep in H929 cells. Furthermore, down-regulation of ALOX5 by RNA interference could also induce apoptosis in H929. Gene expression analysis on MM patient dataset indicated ALOX5 expression was significantly higher in MM patients compared to normal plasma cells. We also found that Bcl-2 was overexpressed in DZNep insensitive cells, and cotreatment with DZNep and ABT-737, a Bcl-2 family inhibitor, synergistically inhibited growth and induced apoptosis of DZNep insensitive MM cells. Taken together, this study shows one of mechanisms of the DZNep efficacy on MM correlates with its ability to down-regulate the ALOX5 levels. In addition, DZNep insensitivity might be associated with overexpression of Bcl-2, and the combination of ABT-737 and DZNep could synergistically induced apoptosis. These results suggest that DZNep may be exploited therapeutically for a subset of MM.

Phosphorylation-mediated EZH2 inactivation promotes drug resistance in multiple myeloma

“…Consistent with our previous reports in which adhesion-mediated signals from fibronectin-engaged VLA-4 play critical roles in the establishment of CAM-DR in MM cells (17, 18), Figure 4E). This is compatible with previous studies showing that it was not DZNep, but chaetocin, that exerted significant cytotoxicity against MM cells (19,20). Furthermore, we examined the effects of EZH2 knockdown on anti-MM drug-induced cytotoxicity because H3K27 trimethylation was mainly catalyzed by EZH2.…”

EZH2 overexpression in natural killer/T-cell lymphoma confers growth advantage independently of histone methyltransferase activity

“…by guest www.bloodjournal.org From compound capable of depleting PRC2 components called DZNep. 31 As reported previously, [31][32][33][34] DZNep effectively and dose-dependently reduced cellular levels of EZH2 in KHYG1 and NKYS, resulting in apoptosis as detected by PARP cleavage using western blot and Annexin V analysis by flow cytometry in a dose-dependent manner ( Figure 6A,C). At the same time, CCND1 is downregulated by DZNep at both the mRNA and protein levels ( Figure 6A-B).…”

PRIMA-1, a Mutant p53 Reactivator, Restores the Sensitivity of TP53 Mutant-Type Thyroid Cancer Cells to the Histone Methylation Inhibitor 3-Deazaneplanocin A

“…Although DZNep exhibits promising antitumor effects, emerging evidence suggests that specific molecular factors determine the DZNep response or resistance in different tumors. For example, it has been reported that ALOX5 levels may contribute to DZNep sensitivity in multiple myeloma cells (24). Moreover, estrogen receptor-negative breast cancers with low BRCA1 levels may be particularly sensitive to DZNep (25).…”