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Abstract :
[en] Multiple myeloma is an incurable hematological malignancy located in the bone marrow. Nowadays, disease management is still complicated due to drug resistance leading to relapses for patients. Therefore, it is of high interest to identify new cell surface antigens that could act as targets of several immunotherapeutic approaches including monoclonal antibodies as well as promising active therapies such as chimeric antigen receptor T cells (CART cells).
Since clinical proteomics usually involves complex samples (cell proteome), the use of highly resolutive and sensitive instruments to perform comprehensive analysis of those complex proteomes is relevant.
Capillary zone electrophoresis tandem mass spectrometry (CZE-MS/MS) is an interesting tool for proteomic analysis as the separation principle is different to liquid chromatography tandem mass spectrometry (LC-MS/MS). Therefore, the combination of both techniques can bring complementary information to enlarge proteome coverage.
In this study, sample preconcentration techniques were investigated in order to improve sample loading and therefore sensitivity. The use of dynamic pH junction (DPJ) allowed the identification of more peptides and proteins compared to conventional injections. Besides, an approximate 100-fold gain in sensitivity was observed using DPJ.
Then, a nanoflow sheath liquid interface (EMASS-II) was compared to the traditional coaxial sheath liquid interface (Triple tube). The use of EMASS-II interface allowed the identification of approximately two times more peptides and proteins thanks to an improvement in sensitivity. Indeed, compared to the Triple tube, peak height and peak area were improved by a factor of 12 and 23-fold, respectively.
Finally, data obtained using CZE-MS/MS was compared to those acquired using LC-Chip-MS/MS. Interestingly, 50% of the identified proteins obtained with CZE were unique to this electrophoretic technique. Therefore, we consider that the interest of using CZE-MS/MS for clinical proteomic studies is high.
In conclusion, we were able to overcome the lack of sensitivity resulting from CZE-MS coupling interface by using online preconcentration and a nanoflow sheath-liquid interface, namely EMASS-II. Besides, the results also proved that proteome coverage is enhanced when CZE and LC-Chip are used in combination owing to their orthogonality.
