Combining CRISPR/Cas9 mutagenesis and a small-molecule inhibitor to probe the function of MELK in cancer

Giuliano, C. J.; Lin, A.; Smith, J. C.; Palladino, A. C.; Sheltzer, J. M.

doi:10.1101/203984

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bioRxiv · 10.1101/203984

Combining CRISPR/Cas9 mutagenesis and a small-molecule inhibitor to probe the function of MELK in cancer

Giuliano, C. J.·Lin, A.·Smith, J. C.·Palladino, A. C.·Sheltzer, J. M.

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Abstract

The Maternal Embryonic Leucine Zipper Kinase (MELK) has been identified as a promising therapeutic target in multiple cancer types. MELK over-expression is associated with aggressive disease, and MELK has been implicated in numerous cancer-related processes, including chemotherapy resistance, stem cell renewal, and tumor growth. On the basis of these findings, a MELK inhibitor is currently being tested in several clinical trials. Here, we report that cancer cell lines harboring CRISPR/Cas9-induced null mutations in MELK exhibit wild-type growth in vitro, under environmental stress, in the presence of multiple chemotherapy agents, and in vivo. By combining our MELK-knockout clones with a recently-described, highly-specific MELK inhibitor, we further demonstrate that the acute inhibition of MELK results in no specific anti-proliferative phenotype. Analysis of gene expression data from cohorts of cancer patients identifies MELK expression as a correlate of tumor mitotic activity, explaining its association with poor clinical prognosis. In total, our results demonstrate the power of CRISPR/Cas9-based genetic approaches to investigate cancer drug targets, and call into question the rationale for treating patients with anti-MELK monotherapies.

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Giuliano, C. J., Lin, A., Smith, J. C., Palladino, A. C., Sheltzer, J. M.. 2017-10-16. Combining CRISPR/Cas9 mutagenesis and a small-molecule inhibitor to probe the function of MELK in cancer. https://doi.org/10.1101/203984

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