Identification of glutathione S-transferase π 1 as a prognostic proteomic biomarker for multiple myeloma using proteomic profiling.

Multiple myeloma (MM) is a B-cell hematological malignancy with monoclonal plasma cell proliferation in the bone marrow. Early diagnosis of MM remains difficult due to the lack of specific symptoms and biomarkers. In the present study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the ClinProt system was used to detect potential biomarkers for MM from the bone marrow samples of 30 patients and 30 healthy controls. A total of 10 of the most significantly differentiated peaks between the patients and controls were identified. When patients with MM were compared with controls, 6 peaks with m/z values of 1,779.24, 1,866.32, 2,022.36, 2,878.9, 4,417.76 and 7,155.38 were upregulated, and 4 peaks with m/z values of 1,466.54, 1,520.02, 1,546.53 and 2,991.05 were downregulated. Of these 10 peaks, 4 peaks (pk 8, 1,866.32 Da; pk 15, 2,878.90 Da; pk 17, 2,991.05 Da; and pk 3, 1,520.02 Da) were further sequenced and identified using liquid chromatography/electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Furthermore, the expression of fibronectin 1 and glutathione S-transferase pi 1 (GSTP1) were validated in patients with MM via ELISAs. Clinical data and statistical analysis indicated that GSTP1 expression was closely associated with the clinical stage of patients with MM. High GSTP1 levels were an independent risk factor for worse prognosis in patients with MM. These results demonstrate that GSTP1 may be a novel biomarker for early diagnosis, prognosis and monitoring of minimal residual disease in MM.