CENPE Inhibition Leads to Mitotic Catastrophe and DNA Damage in Medulloblastoma Cells

Abstract

Medulloblastoma (MB) is the most frequent brain tumor in children. The standard treatment consists in surgery, followed by radiotherapy and chemotherapy. These therapies are only partially effective since many patients still die and those who survive suffer from neurological and endocrine disorders. Therefore, more effective therapies are needed. Primary microcephaly (MCPH) is a rare disorder caused by mutations in 25 different genes. Centromere-associated protein E (CENPE) heterozygous mutations cause the MCPH13 syndrome. As for other MCPH genes, CENPE is required for normal proliferation and survival of neural progenitors. Since there is evidence that MB shares many molecular features with neural progenitors, we hypothesized that CENPE could be an effective target for MB treatment. In ONS-76 and DAOY cells, CENPE knockdown induced mitotic defects and apoptosis. Moreover, CENPE depletion induced endogenous DNA damage accumulation, activating TP53 or TP73 as well as cell death signaling pathways. To consolidate CENPE as a target for MB treatment, we tested GSK923295, an allosteric inhibitor already in clinical trial for other cancer types. GSK923295, induced effects similar to CENPE depletion with higher penetrance, at low nM levels, suggesting that CENPE’s inhibition could be a therapeutic strategy for MB treatment.

Inhibiting microcephaly genes as alternative to microtubule targeting agents to treat brain tumors

“…A molecule that selectively inhibits KIF14 ATPase activity was identified in a screen of small molecules [ 141 ]. Ultimately, a plethora of different molecules have been proposed as CENPE inhibitor: Syntelin, PF-2771, and Compound-A were shown to inhibit CENPE motor domain [ 107 – 109 ]; but the most promising molecule is GSK923295 that has already finished phase I clinical trial for other types of cancers [ 110 ] and it was shown to be effective in MB [ 106 ]. In conclusion, inhibition of KNL1, CENPE, ASPM, CITK, and KIF14 may mimic the effects of MTAs on cell division but could work with particular effectiveness on brain tumor cells, underscoring the importance of developing specific inhibitors and test them in clinical trials.…”

“… MCPH 4 KNL1 Kinetochore scaffold 1 Binds microtubules at the kinetochore by two distinct microtubule-binding regions at N-terminal [ 61 ] Chromosome misalignment, no microtubule-kinetochore attachment, and multinucleated cell formation [ 59 , 60 ] KNL1 knockdown decreases the proliferation and cloning ability of GBM cells [ 65 ] MCPH 5 ASPM Abnormal spindle-like, microcephaly-associated protein Controls the number and length of astral microtubules and microtubule disassembly at spindle poles [ 71 , 72 ] Altered spindle orientation, cytokinesis failure, apoptosis [ 67 , 70 , 71 ] ASPM loss impairs GBM and MB tumor growth and increases DNA damage [ 50 , 77 – 80 ] MCPH 13 CENPE Centromere-associated protein E Microtubule motor protein. Promotes microtubule elongation at kinetochore and controls the length of astral microtubules [ 98 – 103 ] Chromosome misalignment, no microtubule-kinetochore attachment, altered spindle orientation, mitotic arrest [ 92 – 94 ] CENPE inhibition reduces proliferation of GBM and MB cells, increases DNA damage and induces mitotic catastrophe [ 105 , 106 ] MCPH 17 CIT Citron Rho-interacting serine/threonine kinase Controls the number and length of astral microtubules and promotes microtubule stabilization at midbody [ 71 , 124 ] Altered spindle orientation, cytokinesis failure, apoptosis [ 120 , 126 ] CITK loss impairs MB tumor growth, increases DNA damage and the sensitivity to radiation and cisplatin …”

“…In pediatric high-grade glioma cell lines, CENPE knockdown, alone or in combination with TZM, reduces cell proliferation and induces cell cycle arrest [ 105 ]. Moreover, CENPE knockdown induces mitotic catastrophe and DNA damage in MB cell lines [ 106 ]. All together these data suggest that CENPE could be a potential target in GBM and MB treatment, blocking microtubule stabilization and impairing mitosis (Table 2 ).…”

“…Lastly, the allosteric inhibitor GSK923295 binds the ATPase pocket and has already finished the phase I clinical trial [ 110 ]. This compound was shown to be effective against MB cell lines, where it abolished the clonogenic potential and induced mitotic catastrophe and DNA damage [ 106 ]. Given this result in MB, it would be interesting to test the efficacy of this compound in other in vitro and in vivo HGBT models.…”

Molecular Genetics of Microcephaly Primary Hereditary: An Overview

“…CENPE is required for capturing spindle MTs and attachment to the kinetochores [ 102 , 103 ]. Defects in the organization of spindle MTs and delayed progression of the mitosis, leading to abnormal exit from mitosis have been described in MCPH13 patient-derived cell lines as well as in medulloblastoma [ 101 , 104 ]; the presence of binucleate cells of unequal size suggests that, in the absence of CENPE, chromosome segregation and cytokinesis fails [ 101 , 104 ]. Knockout of Cenpe in mice is embryonic lethal, however, in conditional mutants, severe mitotic chromosome misalignment and chromosome segregation fails, in accordance with the observations in human cells [ 105 , 106 ].…”