Identification of a Novel c-Myc Inhibitor 7594-0037 by Structure-Based Virtual Screening and Investigation of Its Anti-Cancer Effect on Multiple Myeloma

Abstract

Introduction

Multiple myeloma (MM) is an extremely malignant and incurable hematological cancer. Increased expression of the c-Myc oncoprotein is closely associated with shorter overall survival of MM patients, implying that c-Myc is a potential therapeutic target.

Main Methods

We identified a potential c-Myc inhibitor 7594–0037 by structure-based virtual screening from the ChemDiv database. CCK8 assay and flow cytometry were used to detect MM cell viability, cell cycle and apoptosis. Q-PCR and Western blot were used to measure corresponding mRNA and protein expression levels. Protein stability assay measured the stability of c-Myc.

Results

Compound 7594–0037 exhibited stronger anti-proliferative activity against MM cells, and induced MM cell cycle G2 phase arrest and apoptosis. More importantly, compound 7594–0037 overcame myeloma resistance to bortezomib and exhibited a synergistic effect with bortezomib, resulting in increased MM cell death. The mechanism consists of compound 7594–0037 facilitating c-Myc protein degradation via decreasing the c-Myc S62 phosphorylation levels mediated by PIM1 kinase. Molecular dynamics simulation with the c-Myc/7594-0037 complex showed that compound 7594–0037 bound tightly to the N-terminus of c-Myc, and blocked the binding interaction of the two termini of c-Myc, which resulted in c-Myc entering into an unstable state.

Conclusion

Overall, our study provides preliminary data for compound 7594–0037, which can be used as a novel c-Myc inhibitor and is a potential candidate therapeutic drug for multiple myeloma.

Keywords:

• multiple myeloma
• c-Myc inhibitor
• virtual screening
• drug resistance
• apoptosis

Acknowledgments

This research was funded by he National Natural Science Foundation of China [grant number 81600173 and 21708033]; the Postdoctoral Science Foundation of China [grant numbers 2018T110554]; the Program for Distinguished Talents of Six Domains in Jiangsu Province (grant number YY-046) and the Qing Lan Project of Jiangsu Province; and Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant No. 18KJB416008).

Abbreviations

MM, multiple myeloma; PIM1, Proviral Insertion site in Moloney Murine Leukemia Virus (MMLV))1; bHLH–LZ, basic-helix-loop-helix leucine zipper; BRD4, bromodomain and extraterminal domain 4; RPMI, Roswell Park Memorial Institute; FBS, fetal bovine serum; PBS, phosphate-buffered saline; MD, molecular dynamics; PI, propidium iodide; BTZ, bortezomib; CHX, cycloheximide; RMSD, root mean square deviation.

Disclosure

The authors report no conflicts of interest in this work.