·Human glioblastoma cell lines (U87, U251 and SF188) and human astrocytes were cultured in vitro. The cells were treated with NCX blockers SN-6, YM244769, SEA0400, CB-DMB and the chemotherapeutic agent temozolomide (TMZ). SN-6, YM244769 and SEA0400 were selective inhibitors for the reverse operation of NCX; while CB-DMB was NCX bidirectional blocker, but preferentially blocked the forward mode of NCX. The TMZ was used as a reference drug. Cell counting kit-8 (CCK-8) assay was used to quantify and assess the cell viability, and half maximal inhibitory concentration (IC₅₀) of the drug was obtained. Calcium imaging was used to detect the changes of Ca²⁺ signal in U87 cells treated with NCX inhibitors, and Western blotting was used to detect the expression of mitogen-activated protein kinase (MAPK) signaling pathway proteins. Cellular apoptosis was evaluated by flow cytometry assay.

·CCK-8 results showed that direct application of the NCX bidirectional blocker CB-DMB to glioblastoma cell lines (U87, U251 and SF188) for 48 h caused a dose-dependent growth inhibition with IC₅₀ values of 2.06, 2.19 and 1.82 μmol/L, respectively. In contrast, NCX reverse blockers SN-6, YM244769 and SEA0400 had no significant effect on the growth activity of glioblastoma cells. CB-DMB had little effect on the growth activity of human astrocytes. Calcium imaging and Western blotting results confirmed that CB-DMB blocked the forward transport mode of NCX to elevate intracellular Ca²⁺, causing intracellular calcium overload and then inducing apoptosis of U87 cells and activating MAPK signaling pathway. Flow cytometry assay results showed that the rate of apoptosis induced by CB-DMB in glioblastoma cells was much faster than that induced by TMZ (P=0.002). The combination of CB-DMB and TMZ enhanced the inhibitory effect of TMZ on the growth of tumor cells.

·The inhibitory effect of CB-DMB on the growth of human glioblastoma cells may be related to blocking the forward transport mode of NCX. The plasma membrane NCX is a potential new target for the treatment of human glioblastoma.