Abstract: Objective To investigate the effect of IKKε kinase on hypoxic injury in rat cardiomyocyte cell line H9c2. Methods H9c2 cells, H9c2 cells with IKKε knockdown or overexpression, were cultured in vitro. A hypoxic injury model was established using H9c2 cells. The cells were divided into the following groups: normal control, acute hypoxia, IKKε overexpression, IKKε knockdown, acute hypoxia + IKKε overexpression, and acute hypoxia + IKKε knockdown. The CCK-8 assay was used to detect cell viability. A commercial kit was used to detect the activity of lactate dehydrogenase (lactate dehydrogenase, LDH). Lyso-Tracker staining was employed to detect the level of lysosomal acidification. Immunofluorescence was used to detect the expressions of Beclin-1, LC3-Ⅱ/Ⅰ, and IL-1β. ELISA was applied to detect the concentration of IL-1β. Western blot was carried out to detect the expressions of IKKε, autophagy-related proteins (Beclin-1, LC3, p62), and apoptosis-related proteins (Bcl-2, Caspase-3, Bax). Results Compared with the normal control group, the viability of H9c2 cardiomyocytes in the acute hypoxia control group was weakened, the LDH activity was significantly increased, the level of lysosomal acidification was significantly decreased, autophagy was enhanced, and apoptosis was increased. Compared with the acute hypoxia group, the acute hypoxia + IKKε knockdown group exhibited enhanced cell viability, significantly decreased LDH activity, enhanced autophagy, reduced apoptosis, and an attenuated inflammatory response. The acute hypoxia + IKKε overexpression group showed results opposite to those of the acute hypoxia + IKKε knockdown group. Conclusions Knocking down IKKε can alleviate hypoxic-induced injury in H9c2 cardiomyocytes, and the mechanism may be related to enhanced autophagy, reduced apoptosis, and an attenuated inflammatory response.

Key words: IKKε kinase, autophagy, apoptosis, hypoxic injury of cardiomyocytes, H9c2 cells