Downregulation of SPHK1 expression decreases the resistance of glioma cells to apoptosis.

<p>(A) SPHK1 knockdown was achieved by introducing specific shRNAs in glioma cells. α-tubulin was used as a loading control. (B) Silencing of SPHK1 led to significant decrease of enzymatic activity in glioma cells. (C) Knockdown of SPHK1 enhances cell death. (D) SPHK1 knockdown enhanced the sensitivity of glioma cells to adriamycin-induced apoptosis. Quantification of TUNEL positive cells (left panel) and Annexin V⁺/PI⁻ cells (right panel). Results are expressed as percentages of total cells. (E) PARP cleavage and cleaved caspase 3 levels were assessed in indicated cell lines treated with UV irradiation (40 J/m²) or adriamycin (1.0 µM) for 24 h via WB. α-tubulin was used as a loading control. For (B), (C) and (D), error bars represent mean ± SD from three independent experiments with similar results. *, <i>p</i><0.05.