ABSTRACT
Epidermal growth factor receptor (EGFR) and its ligand heparin-binding EGF-like growth factor (HB-EGF) sustain endothelial cell proliferation and angiogenesis in solid tumors, but little is known about the role of HB-EGF-EGFR signaling in bone marrow angiogenesis and multiple myeloma (MM) progression. We found that bone marrow endothelial cells from patients with MM express high levels of EGFR and HB-EGF, compared with cells from patients with monoclonal gammopathy of undetermined significance, and that overexpressed HB-EGF stimulates EGFR expression in an autocrine loop. We also found that levels of EGFR and HB-EGF parallel MM plasma cell number, and that HB-EGF is a potent inducer of angiogenesis in vitro and in vivo. Moreover, blockade of HB-EGF-EGFR signaling, by an anti-HB-EGF neutralizing antibody or the EGFR inhibitor erlotinib, limited the angiogenic potential of bone marrow endothelial cells and hampered tumor growth in an MM xenograft mouse model. These results identify HB-EGF-EGFR signaling as a potential target of anti-angiogenic therapy, and encourage the clinical investigation of EGFR inhibitors in combination with conventional cytotoxic drugs as a new therapeutic strategy for MM.
ABSTRACT
Multiple myeloma (MM) is a genetically heterogeneous disease that includes a subgroup of 10-15% of patients facing dismal survival despite the most intensive treatment. Despite improvements in biological knowledge, MM is still an incurable neoplasia, and therapeutic options able to overcome the relapsing/refractory behavior represent an unmet clinical need. The aim of this review is to provide an integrated clinical and biological overview of high-risk MM, discussing novel therapeutic perspectives, targeting the neoplastic clone and its microenvironment. The dissection of the molecular determinants of the aggressive phenotypes and drug-resistance can foster a better tailored clinical management of the high-risk profile and therapy-refractoriness. Among the current clinical difficulties in MM, patients' management by manipulating the tumor niche represents a major challenge. The angiogenesis and the stromal infiltrate constitute pivotal mechanisms of a mutual collaboration between MM and the non-tumoral counterpart. Immuno-modulatory and anti-angiogenic therapy hold great efficacy, but variable and unpredictable responses in high-risk MM. The comprehensive understanding of the genetic heterogeneity and MM high-risk ecosystem enforce a systematic bench-to-bedside approach. Here, we provide a broad outlook of novel druggable targets. We also summarize the existing multi-omics-based risk profiling tools, in order to better select candidates for dual immune/vasculogenesis targeting.
ABSTRACT
The investigational drug MP0250 is a multi-specific DARPin® molecule that simultaneously binds and neutralizes VEGF and HGF with high specificity and affinity. Here we studied the antiangiogenic effects of the MP0250 in multiple myeloma (MM). In endothelial cells (EC) isolated from bone marrow (BM) of MM patients (MMEC) MP0250 reduces VEGFR2 and cMet phosphorylation and affects their downstream signaling cascades. MP0250 influences the secretory profile of MMEC and inhibits their in vitro angiogenic activities (spontaneous and chemotactic migration, adhesion, spreading and capillarogenesis). Compared to anti-VEGF or anti-HGF neutralizing mAbs, MP0250 strongly reduces capillary network formation and vessel-sprouting in a Matrigel angiogenesis assay. MP0250 potentiates the effect of bortezomib in the same in vitro setting. It significantly reduces the number of newly formed vessels in the choriollantoic membrane assay (CAM) and the Matrigel plug assay. In the syngeneic 5T33MM tumor model, MP0250 decreases the microvessel density (MVD) and the combination MP0250/bortezomib lowers the percentage of idiotype positive cells and the serum levels of M-protein. Overall results define MP0250 as a strong antiangiogenic agent with potential as a novel combination drug for treatment of MM patients.
ABSTRACT
OBJECTIVE: Alterations in the handling of renal salt reabsorption may contribute to interindividual differences in blood pressure regulation and susceptibility to hypertension. CLC-K chloride channels and their accessory subunit barttin play a pivotal role in kidney by controlling chloride and water absorption. Compounds selective for CLC-Ks, such as the benzofuran derivative MT-189, may have a significant therapeutic potential. Here, we assessed the feasibility of using CLC-K blockers in hypertension and aimed at enhancing drug inhibitory affinity. METHODS AND RESULTS: We demonstrated that acute in-vivo administration of MT-189 to spontaneously hypertensive rats (SHR) caused a reduction of blood pressure and defined the CLC-K/barttin gene expression pattern in kidney of SHR in comparison with normotensive Wistar-Kyoto rats. Based on MT-189, we designed and tested a new series of benzofuran derivatives on CLC-K chloride channels heterologously expressed in HEK293 cells. These studies enabled us to elucidate the causative molecular relationship for obtaining the most potent and selective inhibitor (SRA-36) described so far, with an IC50 of 6.6â±â1âµmol/l. The biophysical and pharmacological characterization of A447T CLC-Ka and Y315F CLC-Ka, both polymorphisms associated with hypertension, showed that SRA-36 is an efficacious inhibitor of the chloride currents sustained by these polymorphisms. Molecular docking studies allowed hypothesizing an inhibition mechanism for the considered ligands, laying the foundations for the rational design of new and more effective CLC-K inhibitors. CONCLUSION: The SRA-36 molecule represents a new potential therapeutic option for hypertension.
