Cancer specific Mucin‐1 glycoforms are expressed on multiple myeloma

Abstract

SummaryPresent therapies cannot cure the large majority of patients with multiple myeloma (MM) and therefore new treatment strategies are imperative. This study analysed the different glycosylation profiles of Mucin-1 (MUC1) on MM and acute myeloid leukaemia (AML) cells using a series of anti-MUC1 antibodies. Seventy-three per cent of the MM patients had plasma cells that expressed the fully glycosylated forms of MUC1. In contrast to controls, normal bone marrow cells and AML cells, the differentiation-dependent and cancer-associated glycoforms of MUC1 were present on 59% and 36% MM tumour cells respectively. This indicated that aberrantly glycosylated MUC1 is a potential immunotherapeutic target in MM patients.Keywords: multiple myeloma, Mucin-1, glycoforms, immunotherapy, tumour-associated antigens. Flow cytometryBM samples were prepared for flow cytometry according to standard procedures. All incubations were at room temperature and samples were washed in between. Briefly: following lysis of erythrocytes, cells were incubated with a series of anti-MUC1 mAbs (van Leeuwen et al, 2006) or isotype control (BD Biosciences, San Diego, CA, USA). Subsequently, cells were incubated with a PE-conjugated rabbit anti-mouse IgG antibody (Dako, Glostrup, Denmark), after which unoccupied binding sites were blocked by incubation with normal mouse serum. Finally, cells were stained with CD38-fluorescein isothiocyanate (FITC), CD45-peridinin chlorophyll (PerCP), CD34-allophycocyanin (APC) or CD11c-APC, CD33-FITC (all: BD Biosciences), followed by fixation, and acquisition of 10 6 events for each sample using a FACSsort cytometer (BD Biosciences). Staining intensities for MUC1 were defined by the mean fluorescence intensity (MFI) ratios (MFI specific antibody/MFI isotype control). An MFI ratio that was greater than the average MFI ratio of control cells (CD34 + cells present in BM from MM patients) + 2 standard deviations (SD) was considered as positive for MUC1 expression. Results and discussionThe monoclonal PC causing MM can have an immature and mature phenotype based on their differential expression of CD45 (Schneider et al, 1997;Kumar et al, 2003). As demonstrated in Fig 1A, et al, 1996). BM from all MM patients had a MPC population, while 19 patients also had an IPC subset. The histograms in Fig 1C show that the different glycoforms of MUC1 were detected on IPC as well as MPC, with a similar expression profile. None of the groups 2 and 3 mAbs reacted with control cells or BM cells from normal donors, including non-malignant PC, although a subset of these cells were stained occasionally by antibodies from group 1 (data not shown). Figure 2A demonstrates that MPC from 59% and 36% of the MM patients bound antibodies from groups 2 and 3, respectively, while 73% were positive for group 1 antibodies. A similar trend was observed for IPC although less samples reacted with antibodies from groups 2 and 3 (Fig 2B). Staining of PC by group 2 and/or 3 antibodies was always accompanied by intense recognition by antibodies from grou...

MUC1-C drives MYC in multiple myeloma

“…[13][14][15][16][17][18] In addition, the WNT/b-catenin pathway is activated in MM and is a potential target for the treatment of MM. [57][58][59] However, the mechanism(s) responsible for activation of WNT signaling in MM cells has been unclear.…”

“…MUC1-C is aberrantly expressed in MM cell lines and primary MM cells. [13][14][15][16][17][18] The MUC1-C cytoplasmic domain binds directly to b-catenin and inhibits b-catenin degradation. 22 The MUC1-C cytoplasmic domain also functions as a substrate for GSK3b and blocks GSK3b-mediated b-catenin phosphorylation.…”

“…[13][14][15][16][17][18] MUC1 consists of 2 subunits. 19 The MUC1 N-terminal extracellular subunit includes glycosylated tandem repeats that are characteristic of the mucin family.…”

Targeting MUC1-C is synergistic with bortezomib in downregulating TIGAR and inducing ROS-mediated myeloma cell death

“…[17][18][19][20][21][22] However, the functional significance of MUC1 expression in MM cells remains poorly understood. Certain insights into MUC1 function have evolved from the finding that MUC1 is translated as a single polypeptide which undergoes autocleavage into 2 subunits in the ER that, in turn, form a stable heterodimer at the cell surface.…”

Survival of Human Multiple Myeloma Cells Is Dependent on MUC1 C-Terminal Transmembrane Subunit Oncoprotein Function

“…The MUC1 oncoprotein is aberrantly expressed by most, if not all, multiple myeloma cell lines and primary patient samples (Takahashi et al, 1994;Burton et al, 1999;Treon et al, 1999;Paydas et al, 2001;Cloosen et al, 2006;Baldus et al, 2007;Kawano et al, 2008). MUC1 consists of two subunits that form a heterodimeric complex at the cell membrane (Kufe, 2009).…”