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. 2011 Jan 14;18(6):959–973. doi: 10.1038/cdd.2010.170

Figure 3.

Figure 3

Increased Mdk expression confers human glioma cells resistance to THC. (a) Kaplan–Meier survival curves for 115 glioblastoma tumors from patients collected at the Virgen de la Salud Hospital (Toledo) and classified according to Mdk expression. Mdk expression is associated to a lower overall survival of GBM patients (P<0.037). Mdk positive or negative expression is shown by green or blue lines, respectively. OS: overall survival. (b) Mdk concentration, as determined by ELISA, in the supernatant of 10 human glioma cell lines (mean±S.D.; n=3; **P<0.01 from each THC-sensitive glioma cell line). (c and d) Effect of THC on the viability (72 h) of T98 (c) and HG2 (d) cells transfected with control (siC) or midkine-selective (siMdk) siRNA (mean±S.D.; n=5 for each cell line, **P<0.01 from vehicle-treated, siC-transfected cells and from vehicle-treated, siMdk-transfected cells and ##P<0.01 from THC-treated, siC-transfected cells). Mdk mRNA levels (as determined by real-time quantitative PCR) were reduced in siMdk-transfected cells relative to their corresponding siC-transfected cells by 81±9% (T98 cells) and 84±9% (HG2 cells), respectively (n=5 for T98 and HG2 cells). (e) Effect of THC on the viability of U87 cells incubated with conditioned medium (C.M.) obtained from U87 or T98 cells. When indicated, the corresponding C.M. was pre-incubated with a neutralizing anti-Mdk (α-Mdk) or isotype unspecific (α-Unsp) antibody (mean±S.D.; n=4; **P<0.01 from vehicle-treated cells, #P<0.05 or ##P<0.01 from THC-treated, U87 C.M.-incubated cells and ΦΦP<0.01 from THC-treated, T98 C.M.-incubated cells). (f) Effect of THC on the viability of U87 cells incubated with exogenous Mdk (mean±S.D.; n=5; **P<0.01 from vehicle-treated cells and ##P<0.01 from THC-treated cells not incubated with Mdk)