Fig. 6.

MYXV infection of BTICs resulted in loss of stem cell markers in vitro and in vivo. (A) BTIC lines BT012, -25, and -48 spheres were infected with 1 MOI of MYXV GFP and stained for nestin, Sox2, and TuJ1 24 h after infection. MYXV is able to infect both nestin- and Sox2-positive cells, demonstrating its ability to target the stem cell fraction within the sphere. (B) All BTICs lost protein expression of stem cell markers Sox2 and/or Musashi-1 (MSI) following MYXV infection with 5 MOIs. Protein collected 24 h post-infection with MYXV with (M + R) or without (M) a 2-h pretreatment with 100 nM rapamycin compared with control (CT) or rapamycin alone (R). Phospho-P70 (pP70) blots demonstrate that the concentration of rapamycin we used was sufficient to inhibit mTOR activity. (C) BT025 was implanted in SCID mice and treated with MYXV, rapamycin, or the combination therapy starting 5 wk post-implantation for a total of 2 wk. Tumors were resected and flow cytometery performed looking at human CD133 cell surface expression. Figures are a result of a pool of 5 animals per group, and percent positive results reflect a subtraction of the isotype control for each group.