Identifying Physiological Substrates of the Snf-1-Related Kinase Hunk: New Biomarkers of Kinase Activity and Therapeutic Targets in Metastatic Breast Cancer.

摘要

Kinases play key roles in the etiology of most cancers. Knowing what proteins are phosphorylated by these kinases is necessary to understand how aberrant kinase activity is linked to disease, to reveal new therapeutic targets, and to anticipate effects of kinase inhibition. There is currently an intense interest in identifying therapeutic strategies to regulate kinase activity in cancers, typically using small molecule inhibitors. Highly successful small molecule kinase inhibitors are already in use to treat several forms of cancer. It is relatively straightforward to identify lead small molecule kinase inhibitors, however cost issues preclude the majority from ever reaching patients. To expedite the flow of targeted anticancer agents to patients, the FDA has approved using Phase 0 trials, in which a primary endpoint is to evaluate target modulation in a small number of patient samples to establish mechanism of action. It is absolutely critical to identify direct physiological substrates of kinases so that anti-phosphosite antibodies can be derived to determine if exploratory kinase inhibitor drugs are truly hitting their intended targets in patients. A recent study demonstrated convincingly that the Snf-1-related serine/threonine kinase Hunk is essential for autochthonous tumor metastasis in a MYC-driven breast cancer model. Another recent study reported the development of a novel, efficient approach to identify true physiological kinase substrates from any tissue or cell source termed the Reverse In-gel Kinase Assay (RIKA). The goal of the work in this project was to bring these two advancements together to identify Hunk substrates, providing the first look downstream of the only kinase known to be required for breast cancer metastasis and to inform strategies to block Hunk activity in breast cancer.