Abstract LB031: WNK are drug targets for triple negative breast cancer

Abstract Triple negative breast cancer (TNBC) accounts for 10-20% of breast cancer cases, and is associated with poor diagnosis and prognostics. Due to the lack of therapeutics available, it is urgent to identify biomolecular targets to develop more efficient treatments [1]. Depletion and inhibition of the protein kinase With No Lysine (WNK) reduces migration of breast cancer cells, slowing down TNBC metastasis [2][3]. For this reason, WNKs are promising cancer drug targets. Other works suggest WNKs are also targets for the treatment of hypertension and stroke. The main focus of this work is to understand the molecular mechanisms of this family of proteins, which will help to develop more efficient drugs. WNKs are serine-threonine kinases important in ion transport regulation [4]. WNKs are critical intracellular osmosensors, with their function related to an equilibrium between an inactive dimer and an autophosphorylation-competent monomer. The dimer conformation covers phosphorylation sites [5], while simultaneously trapping water molecules [6]. The water trapping feature is hypothesized to be linked to ion pairs and clusters of charges between the Activation loop and the Catalytic loop. To access the role of these ion pairs, we expressed and purified seven mutants of key amino acids, analyzed their activity, phosphorylation state and sensitivity to ions and pressure. Some of these mutants are more monomeric, active and autophosphorylation competent than the wild-type, elucidating the role of these amino acids in the function of WNKs. Interestingly, some mutants are more sensitive to potassium, which confirms the WNK inhibition site for this ion [7]. [1]B. D. Lehmann et al., “Identification of human triple-negative breast cancer subtypes and preclinical models for selection of targeted therapies,” J. Clin. Invest., vol. 121, no. 7, pp. 2750–67, 2011.[2]S. Shyamasundar, et al., “miR-93 inhibits the invasive potential of triple-negative breast cancer cells in vitro via protein kinase WNK1,” Int. J. Oncol., vol. 49, no. 6, pp. 2629–36, 2016.[3]A. B. Jaykumas et al., “WNK1 Enhances Migration and Invasion in Breast Cancer Models,” Mol. Cancer Ther., vol. 20, no. 10, pp. 1800–08, 2021.[4]D. R. Alessi, et al., “The WNK-SPAK/OSR1 pathway: master regulator of cation-chloride cotransporters,” Sci. Signal., vol. 7, p. 334, 2014.[5]X. Min, et al., “Crystal structure of the kinase domain of WNK1, a kinase that causes a hereditary form of hypertension,” Structure, vol. 12, no. 7, pp. 1303-11, 2004.[6]R. Akella et al., “Osmosensing by WNK Kinases,” Mol. Biol. Cell, vol. 32, no. 18, pp. 1614–23, 2021.[7]J. M. Pleinis et al., “WNKs are potassium-sensitive kinases,” Am. J. Physiol Cell Physiol, vol. 320, no. 5, pp. C703-21, 2021. Citation Format: Liliana dos Reis Teixeira, John Humphreys, Haixia He, Radha Akella, Elizabeth Goldsmith. WNK are drug targets for triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB031.