[PubMed] [Google Scholar] 9

[PubMed] [Google Scholar] 9. leukemia morphology, including monoblastic cases. Reactivity of CSPG4-specific mAb with leukemic blasts was not limited to those with the rearranged MLL gene. CSPG4 was also expressed on AML blasts with a complex karyotype, FLT3 mutation, or NPM1 mutation. The results indicate that CSPG4 is expressed and detectable by flow cytometry using the mAb 225. 28 on a proportion of blasts of all Talnetant hydrochloride subtypes of AML irrespective of cytogenetic and molecular abnormalities. mAb 225.28 could be useful in detecting AML blasts by flow cytometry. Key words: Chondroitin sulfate proteoglycan-4 (CSPG4), Acute myeloid leukemia (AML), Monoclonal antibody (mAb) 225.28, Cytogenetic and molecular abnormalities INTRODUCTION Chondroitin sulfate proteoglycan-4 (CSPG4), a transmembrane proteoglycan, was originally identified as a highly immunogenic tumor antigen on the surface of melanoma cells. It consists of a 280-kDa N-linked glycoprotein and a proteoglycan component with the molecular weight of 450 kDa (1,2). CSPG4 is expressed on the surface of differentiated malignant cells, progenitor cells, and cancer-initiating cells in various types of solid tumors. CSPG4 has been shown to play an important role in the growth, migration, and metastatic dissemination of tumor cells (1,2). The complex mechanisms by which CSPG4 affects tumor progression are currently under investigation, and its association with other cell surface proteins and receptor tyrosine kinases as well as its potential role in modulating functions of these proteins are of special interest. CSPG4 is highly expressed on malignant cells in various types of cancer and therefore is readily available to be targeted by monoclonal antibodies (mAbs). Therefore, investigating the expression of CSPG4 in patients with acute myeloid leukemia (AML) could lead to the development of effective CSPG4-targeted mAb-based therapies. Using a mAb known as 7.1 that recognized the human homolog of the rat NG2 chondroitin ETS1 sulfate proteoglycan molecule, it was previously demonstrated that NG2 expression was variable in AML, correlated with Talnetant hydrochloride 11q23 chromosomal abnormalities and was mostly detectable in monoblastic cases (3C9). Furthermore, its expression had a predictive value, as greater NG2 expression on leukemic blasts correlated with poor responses to Talnetant hydrochloride chemotherapy and shorter progression-free survival. NG2 was not detected on the surface of normal hematopoietic precursor cells or leukemia stem cells (3C9). Expression of CSPG4 on blasts in newly diagnosed AML patients using mAbs specific for the CSPG4 has not been extensively investigated. Also, CSPG4 expression on blasts and its relation to molecular markers known to have prognostic significance in AML merit further investigation. Using hybridoma technology, we generated a mAb 225.28 reactive with CSPG4 and used this mAb to characterize antigenic determinants expressed on AML blasts. Here we evaluate CSPG4 expression on myeloblasts isolated from peripheral blood of newly diagnosed adult AML patients and examine its relationship to different cytogenetic and molecular abnormalities and distinct morphologic subtypes of AML. MATERIALS AND METHODS Patients, Flow Cytometry, and Antibodies Blood samples were obtained from newly diagnosed AML patients prior to any treatment (n?=?18). All subjects signed an informed consent approved by the Institutional Review Board at the University of Pittsburgh. Peripheral venous blood (20C50 ml) was collected into heparinized tubes. The samples were hand-carried to the laboratory and processed using Ficoll-Hypaque gradients. Peripheral blood mononuclear cells (PBMCs) were recovered, washed in AIM-V medium (Invitrogen, Carlsbad, CA, USA), counted in a trypan blue dye, and immediately used for experiments. Mouse anti-human CD33-PE-Cy7 (IgG1) and mouse anti-human CD45-PerCP-Cy5.5 (IgG1) were purchased from eBioscience (San Diego, CA, USA). Mouse anti-human CD34-APC (IgG1), mouse anti-human CD117-PE (IgG1), and all mouse IgG1 isotype controls were purchased from Biolegend (San Diego, CA, USA). DAPI was purchased from Invitrogen (Grand Island, NY, USA). The CSPG4-specific mouse mAb 225.28, an IgG2a, was developed and characterized in Dr. Soldano Ferrones laboratory as previously described (9C11). Briefly, this mAb was generated from a BALB/c mouse immunized at weekly intervals with three injections of 1 1??107 melanoma cells (colo38) treated with recombinant IFN- (1,000 U/ml for 72 h). Splenocytes from immunized mice were hybridized with murine myeloma cells. Hybridization, subcloning, and growth of hybridoma in culture and in the peritoneal cavity of BALB/c mice were performed according to standard procedures (12). Ascitic fluids were obtained, clarified by centrifugation, diluted, and precipitated with 50% saturated ammonium sulfate. The precipitate was dialyzed against 5 mM Tris buffer, pH 7.5, and chromatographed on DEAE-Sepharose in the same buffer. Purity of collected fractions was determined by SDS-PAGE in 7.5% gel under nonreducing conditions; Ig fractions were combined and concentrated to 5C10 mg/ml on Amicon P-30 membrane. For use in flow cytometry, mAb 225.28 was conjugated with fluorescein isothiocyanate (FITC) at the Genomics and Proteomics Facility (University of Pittsburgh, Pittsburgh, PA, USA). Isotype.