Abstract LB054: A novel chemical proteomics approach toward the identification of kinase targets to sensitize tumour cells to the standard of care drug paclitaxel

Abstract Introduction: Chemotherapy, through various signaling pathways changes the kinase activation profiles in tumour cells and it has been shown that blockade of specific kinases led to sensitization of tumour cells to chemotherapeutic drugs. We surmised that, following chemotherapeutic drug treatment, determination of the kinase binding profile of a specific inhibitor using its corresponding chemoprobe may lead to the identification of kinases to be targeted for potentiating the action of the chemotherapeutic drug. The approach we chose to study was to design a chemoprobe carrying a kinase inhibitor warhead to capture and read the kinase binding profiles before and after the chemotherapeutic drug treatment. Our proof-of-concept was made with AB19, a chemoprobe designed with the scaffold of crizotinib, a MET receptor tyrosine kinase inhibitor. The ability of AB19 to bind to MET was validated using KATO-II gastric cancer cells in which MET is amplified. Material and Methods: Gastric cancer cell line KATO-II, prostate cancer cells DU145, PC3 and 22RV1 and normal prostate cells RWPE-1 were used to determine IC50 values for the different drugs alone and in combination with paclitaxel. Cells were lysed 2 h and 24 h after drug treatment. The chemoprobes (control probe or AB19) were subsequently added and kinases captured using magnetic pull down. Proteomics analyses were performed by mass spectrometry. Results: The results showed that AB19 pulled down MET (its primary target) and many other kinases, including LCK, Src, EPHA2, and FAK1 that play an important role in cancer progression. Importantly, the kinase pull-down profiles by the chemoprobe were similar to that reported for free crizotinib, thereby validating the ability of the chemoprobe to simulate the binding of the free drug. In vitro studies with AB19 revealed the following: (a) the kinase pull-down profiles varied with cell lines, with the presence or absence of some important kinases and (b) under conditions where the cells were pretreated with paclitaxel, the kinase profiles between treated and non-treated cells were similar. However, disappearance and appearance of key targets were observed. Based upon the detection of an increase in aurora kinase A (AURKA) and mammalian target of rapamycin (mTOR) spectral counts, we designed 2-drug combinations of specific inhibitors of the latter targets with paclitaxel under equieffective and sequential administrations. Of all the combinations studied, Alisertib (AURKA inhibitor) + paclitaxel was the most synergistic. Conclusion: Taken together, the results suggest that AURKA is a unique target for sensitizing cells to paclitaxel and this novel chemical proteomics approach can be developed as a novel strategy to identify kinase inhibitors capable of significantly sensitizing cancer cells to standard of care drugs. Citation Format: Alaa Omar Baryyan, Ana Belen Fraga Timiraos, Kurt Dejgaard, Bertrand J. Jean-Claude. A novel chemical proteomics approach toward the identification of kinase targets to sensitize tumour cells to the standard of care drug paclitaxel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB054.

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