A novel therapeutic approach targeted notch in multiple myeloma based on small molecules uncoupling receptor-ligand interaction

INTRODUCTION: Multiple myeloma (MM) is an incurable hematological cancer characterized by MM cells accumulation in the bone marrow (BM) that promotes tumor survival and drug resistance. The oncogenic Notch signaling plays a crucial role in MM. Overexpression of Jag1 and 2 ligands leads to aberrant Notch activation in MM that results in tumor growth and stimulates MM cells to establish pathological interactions with BM. The data of our group and literature data showed that all these effects can be interfered by knocking down of Jag1 and 2 expression (1,2). This evidence prompted us to develop a therapeutic tool to selectively inhibit Notch activity using an unprecedented approach based on small molecules disrupting Notch-Jag interaction. EXPERIMENTAL MODEL: 25 top-scoring small molecules able to disrupt Notch-Jag complex were selected in silico by a multistep approach based on protein-protein docking and virtual high-throughput screening of a chemical library Asinex. Two compounds were validated for their biological activity. RESULTS: A Notch responsive reporter assay on HEK293T cells showed that compound 1 and 2 were able to significantly reduce the Notch transcriptional activity in a dose-dependent manner. Compound’s ability to affect MM cell viability was assessed in a cell growth analysis performed on two MM cell lines, U266 and KMS12. A time-course treatment with the compounds showed a dose-dependent MM cell growth inhibition comparable to the effect obtained with Notch pan-inhibitor. CONCLUSION: The proposed approach promises to be effective in inhibiting Notch activity in MM cells. We will expand and optimize candidate compounds to provide a complete preclinical package. REFERENCES: 1. Houde C, et al. Overexpression of the NOTCH ligand JAG2 in malignant plasma cells from multiple myeloma patients and cell lines. Blood. 2004;104(12):3697-704 2. Colombo M, et al. Notch signaling drives multiple myeloma induced osteoclastogenesis. Oncotarget. 2014;5(21):10393-406