Background: Recent findings around long noncoding RNAs (lncRNAs) have opened novel areas of research around their prospective use in overcoming chemoresistance. Herein, we aimed to investigate the role of lncRNA H19 in temozolomide (TMZ) resistance of human glioma cells and the possible mechanisms.
Methods: Short-/long-term oxidative stress was induced, and TMZ-resistant glioma cells (U251^TMZ and LN229^TMZ) were established. Small interfering RNA (siRNA) and overexpression plasmids were used to modulate the expression of H19 and/or luciferase the reporters. The MTT assay and immunoblotting of cleaved caspase-3, cyclin D1, XIAP and Bcl-2 were conducted to evaluate TMZ sensitivity. Luciferase reporter and quantitative real-time PCR (qRT-PCR) assays were used to verify the activation of NF-κB pathways by H19.
Results: Knockdown of H19 in U251^TMZ and LN229^TMZ cells decreased half maximal inhibitory concentration (IC₅₀) values for TMZ and increased cell apoptosis, and H19 overexpression in U251 and LN229 cells led to the opposite effects, indicating that the H19 confers TMZ resistance to glioma cells. Furthermore, knockdown of H19 decreased the NF-κB signaling, which was revealed by repressed reporter activity and declined expression of its downstream targets in TMZ-resistant glioma cells. In contrast, H19 overexpression in U251 and LN229 cells resulted in an increase in NF-κB activation. Blockage of NF-κB activation by its inhibitor abolished TMZ resistance caused by H19 overexpression. Addition of H₂O₂ to induce oxidative stress largely reversed TMZ sensitivity caused by H19 knockdown.
Conclusion: H19 confers TMZ resistance through activating NF-κB signaling and may represent a novel therapeutic target for TMZ-resistant gliomas.
Keywords: H19, oxidative stress, TMZ resistance, NF-κB pathway, glioma