Proteomic Analysis Identifies Oxidative Stress Induction by Adaphostin

Abstract

Purpose: Activities distinct from inhibition of Bcr/abl have led to adaphostin (NSC 680410) being described as “a drug in search of a mechanism.” In this study, proteomic analysis of adaphostin-treated myeloid leukemia cell lines was used to further elucidate a mechanism of action. Experimental Design: HL60 and K562 cells treated with adaphostin for 6, 12, or 24 h were analyzed using two-dimensional PAGE. Differentially expressed spots were excised, digested with trypsin, and analyzed by liquid chromatography–tandem mass spectrometry. The contribution of the redox-active hydroquinone group in adaphostin was also examined by carrying out proteomic analysis of HL60 cells treated with a simple hydroquinone (1,4-dihydroxybenzene) or H2O2. Results: Analysis of adaphostin-treated cells identified 49 differentially expressed proteins, the majority being implicated in the response to oxidative stress (e.g., CALM, ERP29, GSTP1, PDIA1) or induction of apoptosis (e.g., LAMA, FLNA, TPR, GDIS). Interestingly, modulation of these proteins was almost fully prevented by inclusion of an antioxidant, N-acetylcysteine. Validation of the proteomic data confirmed GSTP1 as an adaphostin resistance gene. Subsequent analysis of HL60 cells treated with 1,4-dihydroxybenzene or H2O2 showed similar increases in intracellular peroxides and an almost identical proteomic profiles to that of adaphostin treatment. Western blotting of a panel of cell lines identified Cu/Zn superoxide dismutase (SOD) as correlating with adaphostin resistance. The role of SOD as a second adaphostin resistance gene was confirmed by demonstrating that inhibition of SOD using diethyldithiocarbamate increased adaphostin sensitivity, whereas transfection of SOD I attenuated toxicity. Importantly, treatment with 1,4-dihydroxybenzene or H2O2 replicated adaphostin-induced Bcr/abl polypeptide degradation, suggesting that kinase inhibition is a ROS-dependent phenomenon. Conclusion: Adaphostin should be classified as a redox-active–substituted dihydroquinone.

Oxidative Stress by Targeted Agents Promotes Cytotoxicity in Hematologic Malignancies

“…Closer inspection of the chemical structure of adaphostin reveals that it is a dihydroquinone derivative, and from studies in primary acute myelogenous leukemia (AML) (119) and chronic lymphocytic leukemia (CLL) cells (101), as well as a host of cell lines that do not express BCR=ABL (63,75), it is clear that the activity of adaphostin activity does not depend on the presence of the BCR=ABL kinase. Transcriptional and proteomic profiling of adaphostin effects in a panel of cells that included BCR=ABL-positive and BCR=ABL-nonexpressing cells, provides independent confirmation of these findings (40,106). Upregulation of oxidative stressrelated genes such as heat-shock proteins and proteins such as glutathione S-transferase and superoxide dismutase were described in these studies.…”

A copper chelate of thiosemicarbazone NSC 689534 induces oxidative/ER stress and inhibits tumor growth in vitro and in vivo

“…To terminate the assay, serum-containing media was replaced with serum- and leucine-free RPMI 1640 containing 0.03 µCi of [ 14 C]-leucine and the samples processed as described in Stockwin et al [16]. Results are expressed as % [ 14 C]-leucine incorporation into the control-treated cells.…”

Proteomics Analysis of Alfalfa Response to Heat Stress

“…2-DE in combination with MS allows rapid and reliable protein identification [6], [7]. In recent years, proteomic approaches have been widely used to the systematic study of the responses to a wide range of abiotic stresses, such as cold [8], [9], oxidative stress [10], drought [11], [12] and salt [13]. Most components of the heat stress response mechanism in plants also can be identified through high-throughput proteomic analysis [14], [15].…”