MI-63: A novel small-molecule inhibitor targets MDM2 and induces apoptosis in embryonal and alveolar rhabdomyosarcoma cells with wild-type p53

Abstract

BACKGROUND: Interruption of the role of p53s as a tumour suppressor by MDM2 may be one of the mechanisms by which cancer cells evade current therapy. Blocking the inhibition of wild-type p53 by MDM2 in cancer cells should reactivate p53's tumour suppressor functions and enhance current cancer treatments. MI-63 is a novel non-peptide small molecule that has shown strong binding affinity (K i ¼ 3 nM) for MDM2; however, its effects on paediatric cancer cells and the specific mechanism of tumour suppressor reactivation have not been evaluated. METHODS: Rhabdomyosarcoma (RMS), the most common childhood soft tissue sarcoma, expresses either wild-type or mutant p53 protein. We examined the inhibitory effects of MI-63 in embryonal RMS (ERMS) and alveolar RMS (ARMS) cell lines expressing wildtype or mutated p53. RESULTS: Treatment with MI-63 reduced cell viability by 13.4% and by o1%, respectively, at 72 h in both RH36 and RH18 cell lines expressing wild-type p53. In contrast, RH30 and RD2 cells expressing p53 mutants are resistant to MI-63 treatment. An increased expression of p53, p21 WAF1 , and Bax protein was observed after treatment with MI-63 in RMS cells with wild-type p53, and apoptosis was confirmed by cleaved PARP and caspase-3 expression. However, RD2 and RH30 RMS cells, as well as human normal skeletal muscle cells, showed a minimal increase in p53 signalling and no induction of cleaved PARP and caspase-3. MI-63 was compared with Nutlin-3, a known MDM2 inhibitor, and was found to be more potent in the inhibition of cell proliferation/viability. Further, synergy was observed when MI-63 was used in combination with doxorubicin. CONCLUSION: These results indicate that MI-63 is a potent therapeutic agent for RMS cells expressing wild-type p53 protein.

2-Deoxyglucose Induces Noxa-Dependent Apoptosis in Alveolar Rhabdomyosarcoma

“…Other possible determinants of the sensitivity to 2-DG are p53 and HIF-1, which regulate the glycolytic phenotype. p53 is not functional in any of the 3 sensitive alveolar rhabdomyosarcoma cell lines tested (29,30), which would agree with data that indicate that p53 protects cells from metabolic stress. However, RD cells are also deficient in p53 but still insensitive.…”

“…Apoptosis induced by glucose deprivation in hematopoietic cells is inhibited by overexpression of Bcl-2 or Bcl-x L , and it has been shown to be mediated by Noxa, Puma, or Bim (20,25). We could not detect induction of Puma, possibly because this protein is usually induced in a p53-dependent manner, but the alveolar rhabdomyosarcoma cells used in this study are deficient in p53 (29,30). Consistent with data that suggest that death induced by 2-DG is due to ER stress, we observed induction of Bim, which mediates death induced by ER stress in some systems (37).…”

Ubiquitin becomes ubiquitous in cancer

“…27 The pre-clinical investigation and clinical trials of other anti-MDM2 cancer therapeutic compounds RITA, MI-63 and syl-155 is ongoing, and all of these therapeutics, like Nutlin, are based on targeting the MDM2-p53 interaction. [28][29][30] Another p53 E3 ligase, ARF-BP1, originally purified in a complex with p14 ARF , can directly interact with p53 and induce p53 ubiquitination and degradation. 31 ARF-BP1 is highly expressed in 80% of breast cancer cell lines suggesting a potential role of ARF-BP1 in breast cancer tumorigenesis.…”

A Computational Study of Anticancer Activity of Curcumin Derivatives Using in silico Drug Designing and Molecular Docking Tools

“…A value greater than 2 always shows good BBB passage [16]. Molecular weight must not be greater than 500 Daltons; demethoxycurcumin, bisdemethoxycurcumin, α-elemene, (-) β-elemene, (-) δ-elemene, (-) γ-elemene, curdione, calebin A, ar-turmerone obeys the rule.…”