Fig. 4

Correlation of LAT4expression with the mTOR activation and radiotherapy sensitivity of TMZ-resistant cells. (A) Western blot analysis was conducted to determine the expression levels of LAT4, p-mTOR, and p-S6 in both TMZ-sensitive and -resistant cells. (B) The effect of LAT4 knockdown on the expression levels of p-mTOR and pS6 in TMZ-resistant cells. (C) Cell viability assay results illustrating the OD at 450 nm for TMZ-sensitive and -resistant cells within 96 h, following treatment with either DMSO (control) or TMZ (200 µM), under different radiation conditions (0 Gy and 4 Gy). (D) The expression level of LAT4, p-mTOR, and p-S6 protein in TMZ-resistant cells under the treatment of BCH. (E, F) Representative fluorescence microscopy images of DAPI/γH2AX staining in TMZ-sensitive and -resistant cells within 96 h, after 4 Gy radiation exposure for 0–6 h are presented (E), or treatment with either DMSO or TMZ (200 µM) (F). The fluorescence of DAPI (blue) and γH2AX (red) indicate the presence of nucleus DNA damage and repair foci, respectively. All data from more than three independent experiments are presented as SD. A two-tailed t-test was used for comparisons between the two indicated groups (** p < 0.01, *** p < 0.001)