Figure 5.

The effects of temozolomide on GSCs in vivo (human-derived GBM43 flank model). (a) Figure describing in vivo experiment set up. GBM43 tumors were implanted in the flank of athymic nude mice and treated for 5 consecutive days with different doses of TMZ (2.5, 5, and 10 mg/kg/day) or DMSO. Five days post-therapy tumors were collected, measured, weighed, and analyzed using FACS and immunofluorescence staining. (b) Representative plot depicting the relative tumor volume over time (during the 10 days post-initial therapy). In addition, there is a representation of tumor measure post collection. TMZ treatment was able to cause tumor shrinkage under all conditions and in a dose-dependent manner. (c) FACS analysis of the GSC population in the collected tumors. Suboptimal doses of TMZ (2.5 mg/kg/day) consistently and significantly triggered the highest increase in the GSC population when compared with the control group. This observation was true for the CD133⁺, (d) CD15⁺, and (e) Sox-2⁺ GSC populations. (f) Immunofluorescence staining ( × 20 magnification) with double-positive GSC markers (CD133/Sox2) reaffirmed the above findings. (g) Frequency of CD133, CD133/CD15, and CD133/Sox2 markers in GBM12, GBM26, and GBM39 flank tumors treated with or without TMZ (2.5 mg/kg/day). Error bars represent S.D. from the average of at least five samples. Error bars denote S.E.M. P: ns (P>0.05), *P<0.05, **P<0.01, ***P<0.001, one-way analysis of variance