Isoforms of Ionotropic Glutamate Receptor GRIK2 Induce Senescence of Carcinoma Cells

The aberrant regulation of growth and proliferation is a key feature of carcinoma cells. In order to use molecular strategies to correct these defects toward therapeutic purposes, it is important to characterize the entire spectrum of causative molecules.

By using gene transfer technique, SKOV3 ovarian carcinoma cells were transduced with an expression construct of glutamate receptor 6 (glutamate ionotropic receptor kainate type subunit 2, GRIK2) in retroviral vector PQCXIP. The senescence of transduced cells was subsequently characterized.

Our results demonstrated that retroviral transduction occurs with high frequency and transduced cells continue to proliferate, albeit at a significantly reduced rate, up to 39 days. Some transduced colonies stopped proliferating after 12 days, and none of the clones proliferated beyond 37 days. The doubling time for these transduced cells increased progressively until they reached a complete cell-cycle arrest. The proliferating cells were distinguished by bromodeoxyuridine incorporation and 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay. The growth and cell cycle arrest in transduced cells accompanied activation of senescence-associated β-galactosidase. Furthermore, we have demonstrated a decrease in the levels of active protein kinase B and increase in the abundance of inactive cyclin-dependent kinase 1.

These results indicate involvement of GRIK2 in senescence and suggests GRIK2 as a potential target for therapeutic intervention of cancer cells.