CEP131 Abrogates CHK1 Inhibitor-Induced Replication Defects and Is Associated with Unfavorable Outcome in Neuroblastoma

Figure 1

Increased expression of MDM2 and decreased DNA replication capacity were observed in response to Checkpoint kinase 1 inhibitor (CHK1i, PF-477736): (a) quantitative RT-PCR analysis of MDM2 mRNA levels in various neuroblastoma cell lines treated with 0, 1, and 5 μM CHK1i for 24 h; (b) immunoblot analysis using anti-p53, anti-phosphorylated p53 at Ser¹⁵ (P-p53 ^Ser15), anti-MDM2, anti-p21, or anti-phosphorylated histone H2A.X at Ser¹³⁹ (γH2AX) antibodies in NB-39-nu cells treated at the indicated time points with 1 μM CHK1i; and (c) detection of S phase nuclei. NB-39-nu cells were treated with or without 1 μM CHK1i for indicated time periods and then exposed to EdU for 20 min. One hundred nuclei stained with 4′,6-diamidino-2-phenylindole (DAPI, nuclear DNA, blue) were counted in each of the triplicate sets and the relative numbers of EdU-labeled S phase nuclei (red) were scored. Data are presented as the mean ± SD. and .

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