Mitochondrial dysfunction has been associated with chronic degenerative diseases, aging and cancer. Mitochondrial proteins are interesting targets for the study of apoptosis in leukemia and other malignancies. Modern mass-spectrometry instrumentation has achieved excellent performance in terms of sensitivity, resolution and mass accuracy; however, so far, the contribution of proteomics to the care of patients with AML is virtually zero. Therefore, we set up strategies for the proteomic analysis of the mitochondria enriched cytoplasmic fractions in primary AML cells. Primary AML cells and normal blood cells were derived from bone marrow aspirates of a group of five patients with AML (M1 and M2) at the time of initial diagnosis before chemotherapy and three healthy controls. Peptide mass spectra were obtained on a MALDI-TOF-TOF mass spectrometer. Protein identification was processed and analyzed by searching the Swiss-Prot protein database using the MASCOT search engine of Matrix Science that integrated in the Global ProteinServer Workstation. Tandem electrospray ionization mass spectrometry (ESI-MS/MS) experiments were performed on a quadrupole (Q)-time of flight 2 (Q-TOF2) hybrid quadrupole/TOF mass spectrometry. We identified 48 spots corresponding to 38 proteins in primary AML cells, the expressions of which were altered significantly compared with normal blood cells. Out of these deregulated proteins, totally 12 and 20 proteins were observed in up- or down-regulated spots, respectively. Interestingly, prohibitin (gi4505773) was highly expressed in primary AML cells. Prohibitin is known to induce growth suppression and repress E2F-mediated transcription. But it has recently found that prohibitin protects cells from apoptosis by down-regulating E2F activity when Rb family members are inactive (

Oncogene 2002;21:4539–48
). The current proteomic analysis for primary AML cells supports that prohibitin not only acts as a repressor of E2F activity during normal cellular conditions, but may also aid in the decision between survival and death during times of apoptotic stimulation. Our ongoing studies will try to elucidate the precise role and mechanism in primary AML cells. Six proteins (ADP-ribosylation factor guanine nucleotide-exchange factor 2, cytokeratin-9, vimentin, chain A, kinesin family member 1C and gi34533624 unnamed protein product) were exclusively identified in primary cells. In conclusion, this mitochondrial proteomic analyses enable us to define the deregulated mitochondria-related proteins important for the initiation and the progression of AML. Also, these analyses may promote the identification of new targets for specific treatment approaches in AML.

Topics:
adp-ribosylation factors, bone marrow aspiration, cancer, chemotherapy regimen, cytoplasm, degenerative disorders, growth retardation, guanine nucleotide exchange factors, leukemia, mass spectrometry

Author notes

Disclosure: No relevant conflicts of interest to declare.

2007, The American Society of Hematology
2007
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