Fig. 5: The effect of riluzole on xCT expression in xenograft tumors, riluzole resistant human cell lines, and tumor biopsies from a riluzole monotherapy phase II clinical study.
From: Participation of xCT in melanoma cell proliferation in vitro and tumorigenesis in vivo
a Quantification of endogenous xCT protein expression by western immunoblots using excised xenografts derived from human melanoma cell lines, C8161 and 1205Lu. Xenografted tumors were treated with vehicle (DMSO) or riluzole (7.5 mg/kg) daily by oral gavage for 3 weeks. Western blot data shows decreased level of endogenous xCT protein in riluzole treated samples compared to vehicle-treated ones (left panel). Quantifications were done and normalized to GAPDH (right panel). For the bar graphs, values are presented as the mean ± SEM from three independent experiments; *P < 0.05, compared with each control (Veh). b Western immunoblots assessing endogenous xCT levels in pre- and post-riluzole treated patient tumors from phase II riluzole monotherapy clinical trial. High endogenous level of xCT in post-treatment tumors are generally correlated with poor prognosis (4/7). Three clinically responded stable disease patients (PT1, PT11, PT5) showed a decreased level of xCT protein in post-treatment compared to that of pre-treatment samples. β-actin was used as loading control. c Melanoma cells resistant to riluzole were selected by growing cells in the presence of low concentration of riluzole (5 μM) for 3 passages. Protein lysates were prepared and subjected to western immunoblots. Relative expression of xCT was presented as a fold ratio compared to PA. PA, parent cells, RR, riluzole resistant cells
