Abstract 496: Checkpoint kinase 1 inhibition suppresses cell growth and enhances cisplatin sensitivity in medulloblastoma cells
Bibliographic record
Abstract
Abstract Background: Medulloblastoma is the most common malignant brain tumor in children and remains a therapeutic challenge due to its significant therapy-related morbidity. Checkpoint kinase 1 (CHK1) is highly expressed in many cancers and regulates critical steps in mitotic progression and DNA-damage response. Activation of CHK1 pathway promotes treatment resistance in tumor cells. Recent studies suggest that targeting CHK1 with a small molecule inhibitor, to sensitize tumors to a variety of DNA-damaging agents, is a promising approach to tumor therapy. Methods: The expression of CHK1 mRNA in medulloblastoma patient samples and cell lines were examined using microarray analysis and qRT-PCR respectively. Western blot analysis was conducted on medulloblastoma cell lines to analyze expression level of CHK1 protein. The effect of AZD7762, a small molecule inhibitor of CHK1, on colony forming ability of medulloblastoma cell lines in combination with cisplatin was examined using colony formation assay and methylcellulose assay. The impact of AZD7762 in combination with cisplatin on tumor cell proliferation was further evaluated in real-time using xCELLigence. The effect of AZD7762 on cell viability was assessed using Guava ViaCount assay. Furthermore, the effects on key signaling pathways were analyzed using immunofluorescence, senescence assay, and apoptosis assay. Results: Analysis of gene expression and western blot experiments revealed that CHK1 mRNA and protein levels are over expressed in all medulloblastoma patient samples and in cell lines when compared to normal pediatric cerebellum. High CHK1 expression correlates with adverse outcomes in a large cohort of medulloblastoma patients. Inhibition of CHK1 by a low nanomolar concentration of AZD7762 potently inhibited cell growth, suppressed the colony-forming ability, and increased cellular apoptosis of medulloblastoma cells. Furthermore, AZD7762 pretreatment sensitized medulloblastoma cells to cisplatin synergistically. Conclusions: CHK1 expression is a prognostic marker in medulloblastoma and targeting CHK1 with a small molecule inhibitor, in combination with cisplatin, is an attractive strategy in treatment of medulloblastoma that warrants further investigation. Citation Format: Monil Shah, Eric Prince, Sujatha Venkataraman, Ilango Balakrishnan, Irina Alimova, Peter Harris, Marc Remeke, Michael D. Taylor, Michael H. Handler, Nicholas K. Foreman, Rajeev Vibhakar. Checkpoint kinase 1 inhibition suppresses cell growth and enhances cisplatin sensitivity in medulloblastoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 496. doi:10.1158/1538-7445.AM2015-496
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".