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Figure S3 from Diffuse Intrinsic Pontine Glioma Cells Are Vulnerable to Mitotic Abnormalities Associated with BMI-1 Modulation

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posted on 2023-04-03, 17:23 authored by Shiva Senthil Kumar, Satarupa Sengupta, Xiaoting Zhu, Deepak Kumar Mishra, Timothy Phoenix, Lisa Dyer, Christine Fuller, Charles B. Stevenson, Mariko DeWire, Maryam Fouladi, Rachid Drissi

A, Soft agar assay of an additional cell line, CCHMC-DIPG-1, to assess sensitization to IR when treated with PTC596 and its respective quantification. Error bars represent the SD from two independent experiments run in triplicate. B, Relative cell growth calculated by WST-1 assay at Day 7 used to calculate the CI values in figure 4C. Three independent experiments were performed and data from one experiment is shown as a representative result. Error bars represent the SD from triplicates.

Funding

CancerFree KIDS Pediatric Cancer Research Alliance

Pray Hope and Believe Foundation

PTC Therapeutics

Cure Starts Now Foundation

Division of Oncology, and the Brain Tumor Center

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ARTICLE ABSTRACT

Diffuse intrinsic pontine glioma (DIPG) is a poor-prognosis pediatric brain tumor with a median survival of less than 1 year. No effective therapy is currently available, and no therapeutic advances have been made in several decades. We have previously identified BMI-1 as a potential therapeutic target in DIPG and have shown that BMI-1 is highly expressed in DIPG tumors regardless of histone 3 subtype. In the present study, we show that the modulation of BMI-1 leads to DNA damage, M phase cell-cycle arrest, chromosome scattering, and cell death. Interestingly, EZH2 inhibition did not alter these effects. Furthermore, modulation of BMI-1 sensitizes DIPG patient-derived stem-like cells to ionizing radiation (IR). Treatment of DIPG stem-like cells with PTC596, a BMI-1 modulator, and IR impairs the kinetics of DNA damage response (DDR). Both DDR foci formation and resolution were delayed, resulting in further reduction in cell viability compared with either treatment alone. In vivo, treatment of mice bearing DIPG xenografts with PTC596 leads to decreased tumor volume and growth kinetics, increased intratumoral apoptosis, and sustained animal survival benefit. Gene expression analysis indicates that BMI-1 expression correlates positively with DIPG stemness and BMI-1 signature. At the single-cell level, the analysis reveals that BMI-1 pathway is upregulated in undifferentiated cells and positively correlates with stemness in DIPG tumors. Together, our findings indicate that BMI-1 modulation is associated with mitotic abnormalities, impaired DDR, and cell death, supporting the combination of BMI-1 modulation and radiation as a promising novel therapy for children with DIPG.

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