Abstract P005: GRK4 Inhibitors Suppress Breast Cancer Cell Growth And Potentiate The Inhibitory Effect Of Dopaminergic D 1 Receptor Agonist SKF38393

Autor: Peng Xu, Katherine Schiermeyer, Jiping Wang, Stephen Marshall, Wei Yue, John J Gildea, Robin A. Felder
Rok vydání: 2020
Předmět:
Zdroj: Hypertension. 76
ISSN: 1524-4563
0194-911X
DOI: 10.1161/hyp.76.suppl_1.p005
Popis: The renal dopaminergic D 1 receptor (D 1 R) regulates sodium excretion which is terminated by phosphorylation by G protein-coupled receptor kinases 4 (GRK4). GRK4 gene variants are associated with increased GRK4 activity and reduced sodium excretion resulting in hypertension. Breast cancer incidence is higher in hypertensive women. We found that GRK4 is a potential molecule linking these two diseases. We hypothesized that GRK4 inhibitors would be beneficial to patients with hypertension and breast cancer. Three potential GRK4 inhibitors (compounds A, B, and C) were tested for their effect on the growth of breast cancer cells MDA-MB-468, MCF-7, and benign mammary epithelial cells MCF-10A controls. These cell lines had high, low, and no GRK4 expression respectively. Growth of MDA-MB-468 and MCF-7 cells was effectively inhibited by compound C with IC 50 16.8±1.9 nM (n=2). MCF-10A cells were relatively resistant to compound C with IC 50 49.3±4.0 nM (n=3) that is significantly higher than the cancer cells (p50 was 1.5-2.3 μM). Growth inhibition of compound A was similar in MCF-7 and MCF-10A cells but less effective in MDA-MB-468 cells indicating GRK4 inhibition may not be the only target for growth inhibition of this compound. It has been reported that D 1 R agonists inhibit growth of breast cancer cells. We hypothesized that blockade of GRK4 would increase sensitivity of breast cancer cells to the inhibitory effect of a D 1 R agonist. In MDA-MB-468 cells, SKF38393 (SKF) at 20 μM caused a 36% reduction in cell number (from 276.7±0.47E4 to 177.7±4.33E4). Compound C alone reduced cell number by 37% (172.4±0.04E4, 5 nM) and 51% (136.3±7.87E4, 10 nM) respectively. Combination treatment induced more reduction in cell number, 63% (100.4±5.54E4, 5 nM) and 84% (44.1±12.7E4, 10 nM). Similarly, Compound A also enhanced the inhibitory effect of SKF. A left-shift of the SKF dose-response curve in GKR4 knock-down MDA-MB-468 cells confirmed that inhibition of GRK4 increases sensitivity of breast cancer cells to SKF. Our preliminary results suggest that targeting GRK4 with compound C and a dopaminergic agonist could be a novel strategy for breast cancer therapy especially for the patients with hypertension.
Databáze: OpenAIRE
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