Perspectives of proteomics in acute myeloid leukemia

Mass spectrometry-based proteomics and its potential use in haematological research

In the last decade proteomics has made great progress reaching throughput and comprehensiveness comparable to genomics technologies. Mass spectrometry plays a key role in proteomics and has become an indispensable method for molecular and cellular biology because many cellular changes in response to internal or external stimuli can only be detected at the proteome level. Furthermore, different from genomics which depends on the availability of DNA or RNA, proteomics is not restricted to cellular samples, but also allows the analysis of biological fluids like serum, plasma or urine. This article provides an overview of the recent developments in proteomics techniques useful for haematological research.

Proteomics-based prediction of clinical response in acute myeloid leukemia

OBJECTIVE

Response to chemotherapy is achieved in 60% to 70% of patients with acute myeloid leukemia. The ability to predict responders may help in stratifying patients and exploring different therapeutic approaches for nonresponders. Proteomics methods were used to search for predictive factors or combinations of factors.

MATERIALS AND METHODS

Peripheral blood plasma samples from 41 patients with confirmed acute myeloid leukemia with intermediate or poor cytogenetics were obtained prior to induction therapy for proteomic analysis. For each plasma sample, four fractions eluted from a strong anion column were applied to 3 different ProteinChip array surfaces and 12 surface-enhanced laser desorption/ionization spectra were generated. Peaks that correlated with response were identified, and decision trees incorporating these peaks along with various clinical and laboratory findings were constructed to predict response.

RESULTS

Multiple decision trees were constructed. One peak, when combined with age, provided strong positive prediction of responders with 83% accuracy. A second tree, which combined one peak with both cytogenetics and the percent of monocytes in peripheral blood, detected responders with 95% accuracy. A third peak was adequate to predict responders in the intermediate cytogenetic group with 86% accuracy.

CONCLUSIONS

Proteomic analysis should be further explored to define factors important in predicting clinical response in patients with acute myeloid leukemia.

Mass spectrometry based targeted protein quantification: methods and applications

The recent advance in technology for mass spectrometry-based targeted protein quantification has opened new avenues for a broad range of proteomic applications in clinical research. The major breakthroughs are highlighted by the capability of using a "universal" approach to perform quantitative assays for a wide spectrum of proteins with minimum restrictions and the ease of assembling multiplex detections in a single measurement. The quantitative approach relies on the use of synthetic stable isotope labeled peptides or proteins, which precisely mimic their endogenous counterparts and act as internal standards to quantify the corresponding candidate proteins. This report reviews recently developed platform technologies for emerging applications of clinical proteomics and biomarker development.

High correlation of the proteome patterns in bone marrow and peripheral blood blast cells in patients with acute myeloid leukemia

Background

When comparing myelogenous blasts from bone marrow and peripheral blood, immunophenotyping usually show a strong correlation of expression of surface antigens. However, it remains to be determined, whether this correlation also exists on the level of protein expression.

Method

Therefore, we investigated both bone marrow and peripheral blood blast cells from six patients with newly diagnosed acute myeloid leukemia (AML) using conventional two-dimensional electrophoresis in the first dimension and linear polyacrylamide gels (12%) in the second dimension. Proteins were visualized using the silver staining method and image analysis was performed using the PDQuest system.

Results

For each patient over 80 proteins were evaluated in the sample from peripheral blood and bone marrow. We could demonstrate that the protein expression profile of bone marrow did not significantly differ from the expression patterns of peripheral blast cells.

Conclusion

The proteome-set of leukemic blast cells from marrow and blood, does not differ substantially when drawn from AML patients with over 80 percent blast cells in both compartments. This indicates that in AML, blasts from peripheral blood samples can be considered suitable for investigations of the proteome using 2D-electrophoresis.

Proteomics and cancer epidemiology

Profiling of differentially expressed proteins is perhaps the most important and useful approach in developing tools for risk assessment in a population, diagnostic screening, and therapeutics. Proteomic markers have potential for identifying individuals at high risk of developing cancer; however, these markers have not been extensively used in cancer epidemiologic studies. Several markers have to be clinically validated. In this chapter, methods used in proteomic analysis of clinical samples, challenges in the proteomics and cancer epidemiology, and their potential solutions are discussed.

Molecular mechanisms of drug resistance in acute myeloid leukaemia

Resistance to chemotherapy in acute myeloid leukaemia is a major obstacle to a successful outcome for many patients. Often, there is resistance against a broad range of drugs due to multiple, simultaneously active processes. These mechanisms include effects on drug influx and efflux, drug activation/inactivation, DNA repair mechanisms, altered response of end targets, an altered haematopoietic microenvironment and dysfunctional apoptotic pathways. This article reviews the factors that determine leukaemic cell chemosensitivity and discusses the potential for rationally guided therapy.