Figure 5. Macrophage depletion reduces CSC population, tumor size, and SOX2 in vivo.

(A) Representative flow diagrams for control and clodronate A223 treated tumors demonstrate decreased percentage of SP cells for primary and secondary tumors. Secondary tumors refer to SP cells isolated from primary tumors and transplanted into new recipient mice. (B) Reduced SP cell and Non-SP cell populations in clodronate treated mice. Two pairs analyzed per model group. (C) TAM depletion in mice decreased murine SCC tumor growth (mm³). (D) Mouse SCC tumor SOX2 expression decreased with macrophage depletion. Left, representative tumor regions in control and clodronate treated tumors. Right, quantification of SOX2+ cells per mm² tumor for selected regions (control n = 3, clodronate n = 4). (E) Percent CSC population significantly reduced in HM clodronate treated tumors compared to control, but not in NSG clodronate treated tumors (NSG control n = 6, NSG clodronate n = 6, HM control n = 8, HM clodronate n = 8). (F) After 4 weeks clodronate treatment, HM treated tumors were 25% smaller than HM control tumors and 42% smaller than NSG treated tumors, negating null hypothesis (NSG control n = 6, NSG clodronate n = 9, HM control n = 8, HM clodronate n = 8). (G) Human HNSCC PDX SOX2 expression was reduced in HM clodronate treated mice, but not in NSG clodronate treated mice (n = 5 for NSG groups, n = 8 for HM groups). N values represent number of tumors analyzed. For D and G, scale bars: 100μm. Statistical significance in C, D, and E determined by 2-tailed unpaired Student’s t test *P<0.05, ***P<0.001.