The Potential Prognostic Markers for Myelodysplatic Syndromes Studied By Surface Plasmon Resonance Imaging and Mass Spectrometry

Introduction

Myelodysplastic syndromes are clonal hematopoetic stem cell disorders characterized by refractory cytopenias with displasia as a result of ineffective hematopoiesis. Approximately 30 percent of MDS cases progress to acute myeloid leukemia. Excess blasts are the strongest predictors for poor outcome and are associated with disease progression. Because of its heterogeneity and lack of molecular and protein markers that effectively monitor disease progression, clinical management of MDS patients is challenging.

The concentrations of several proteins were found elevated during MDS disease. Their interaction with receptors/ligands is a part of signaling pathways that may play a crucial role in pathogenesis of the disease. Serum levels of vascular cell adhesion protein 1 (VCAM1) and intercellular adhesion molecule 1 (ICAM1) were found higher in MDS patients in comparison with control group and were related to MDS severity. Alpha-2-HS-glycoprotein (FETUA) was analyzed in plasma of MDS patients. Leucine-rich alpha-2-glycoprotein (LRG) was found increased in RAEB-I and RAEB-II patients by proteomic studies.

In this work we developed a protein chip for study of molecular interactions in plasma of MDS patients using surface plasmon resonance (SPR) imaging. Interacting proteins were analyzed and identified using LC-MS/MS.

Methods

Patients with diagnosis of refractory anemia and refractory anemia with ringed sideroblasts (RA/RARS, n=13), refractory cytopenia with multilineage dysplasia (RCMD, n=16), and refractory anemia with excess blasts (RAEB, n=15) as a subgroup of MDS, and MDS patients who progress to acute myeloid leukemia (AML, n=8) were chosen for this study.

The high-resolution SPR imaging (SPRi) system with polarization contrast and internal referencing combined with dispersionless microfluidics was used to study protein interactions. Passive mixing structures were employed to further improve the sensing performance of this SPRi biosensor.

The respective biomarkers (ICAM1, VCAM1, FETUA and LRG) were covalently attached to the functionalized sensor surface and interaction with their counterparts in MDS plasma samples were monitored.

Interacting proteins were removed from the chip surface by diluted NaOH, treated by trypsin, analyzed by nanoLC-MS/MS (TripleTOF 5600) and identified using ProteinPilot database.

Results and Conclusion

Significant differences were observed between analyzed MDS subtypes for VCAM1, FETUA, and LRG (ANOVA: P = 0,00755, P = 0,0306 and P < 0.001 respectively). Using post hoc Tukey contrasts tests we ascertained that sensor responses were significantly higher in group RCMD and AML with respect to the healthy donors for immobilized VCAM1 and in group RA/RARS, RCMD, RAEB and AML with respect to the healthy donors for LRG. Moreover sensor responses were significantly higher in group AML with respect to the RA, RCMD or RAEB for immobilized LRG. Based on our results LRG seems to be a suitable marker of MDS progression.

The identified proteins presented in MDS plasma samples unlike in healthy donor plasma are clusterin, protein S100-A8, serum amyloid A-1 protein, annexin A2, and zinc-alpha-2-glycoprotein among others. S100-A8 and clusterin have been connected with MDS or AML previously; it could be tested as a new protein marker of MDS by SPRi. The results show that SPR biosensors combined with nanoLC-MS/MS are a promising tool for improvement of the diagnosis in complex heterogeneous malignancies.