Widespread Deregulation of Phosphorylation-Based Signaling Pathways in Multiple Myeloma Cells: Opportunities for Therapeutic Intervention

Abstract

Multiple myeloma (MM) is a neoplasm of plasma cell origin that is largely confined to the bone marrow (BM). Chromosomal translocations and other genetic events are known to contribute to deregulation of signaling pathways that lead to transformation of plasma cells and progression to malignancy. However, the tumor stroma may also provide trophic support and enhance resistance to therapy. Phosphorylation of proteins on tyrosine, serine and threonine residues plays a pivotal role in cell growth and survival. Therefore, knowing the status of phosphorylation-based signaling pathways in cells may provide key insights into how cell growth and survival is promoted in tumor cells. To provide a more comprehensive molecular analysis of signaling disruptions in MM, we conducted a kinome profile comparison of normal plasma cells and MM plasma cells as well as their surrounding cells from normal BM and diseased BM. Integrated pathway analysis of the profiles obtained reveals deregulation of multiple signaling pathways in MM cells but also in surrounding bone marrow blood cells compared to their normal counterparts. The deregulated kinase activities identified herein, which include the mTOR (mammalian target of rapamycin)/p70S6K and ERK1/2 (extracellular signal-regulated kinases 1 and 2) pathways, are potential novel molecular targets in this lethal disease.

Feasibility study: Phosphospecific flow cytometry enabling rapid functional analysis of bone marrow samples from patients with multiple myeloma

“…High STAT3 phosphorylation levels have been linked to many cancers including MM . Furthermore, STAT3 deregulation has been observed in MM and has been proposed as a target for therapeutic intervention . In our observation, some samples seem to have a high constitutive level of STAT‐3 phosphorylation, which may be of interest to such investigations.…”

Modulation of Human Peripheral Blood Mononuclear Cell Signaling by Medicinal Cannabinoids

“…Kinome profiling was performed as described in (Fuhler et al, 2011). PBMCs were lysed in ice-cold Pepchip cell lysis buffer (20 mM Tris-HCl, pH 7.5, 150 mM NaCl, 1 mM Na2EDTA, 1 mM EGTA, 1% Triton X-100, 2.5 mM sodium pyrophosphate, 1 mM MgCl2, 1 mM μ-glycerophosphate, 1 mM Na3VO4, 1 mM NaF, 1 μg/ml leupeptin, 1 μg/ml aprotinin, 1 mM PMSF).…”

“…The above-mentioned considerations prompted us to explore the effects of medical marijuana using kinome profiling (Fuhler et al, 2011; Hazen et al, 2011), revealing wide-spread signaling effects of cannabis on peripheral blood mononuclear cells.…”

Development of a robust flow cytometry-based pharmacodynamic assay to detect phospho-protein signals for phosphatidylinositol 3-kinase inhibitors in multiple myeloma

“…Decades of studies have provided the rationale for testing PI3K inhibitors, such as GDC-0941, in cancer prevention and treatment [7-9]. Currently, small molecule inhibitors targeting PI3K and AKT (Perifosine) pathways are being evaluated in clinical trials of MM [10]. …”

“…GCD-0941 is a potent oral pan-PI3K inhibitor that has demonstrated reduced phosphorylation of downstream proteins including S6 ribosomal protein (pS6) in tumor cells by IHC in Phase I studies of patients with solid tumors [12]. From a tumor PD perspective, there are intrinsic caveats with IHC or MSD assays to assess the protein phosphorylation of S6 in MM [10], a blood cancer whose tumor cells reside within the bone marrow with variable tumor content between 5-95% in newly diagnosed patients.…”