Fig. 4.

Impact of stable ALDH1A2 silencing in an orthotopic mouse xenograft model. a Western blot analysis with whole cell lysate of FaDu-mock and FaDu-shALDH1A2 clones confirms stable silencing of ALDH1A2, while no alteration in RARβ protein level was detected. Detection of β-Actin served as control for quantity and quality of protein lysates. b Representative pictures of IHC staining with tumor sections derived from FaDu-mock or FaDu-shALDH1A2-injected xenografts to analyze ALDH1A2 expression, tumor cell proliferation (Ki67), apoptosis (cleaved caspase 3) and the mesenchymal-like phenotype (Vimentin). Counterstaining with hematoxylin to visualize tissue architecture; scale bar = 20 μm. c The graph represents quantification of the tumor volume (in mm³) in mice (n = 4 per group) at the indicated time points after implantation with either FaDu-mock or FaDu-shALDH1A2 clones. Dashed line indicates surgical threshold. Mean values ± SD and p values are given in Additional file 2: Table S5. d Representative pictures of an IHC staining (brown signal) with serial tumor sections demonstrate inverse expression of ALDH1A2 and vimentin in OPSCC. Counterstaining with hematoxylin to visualize tissue architecture; white bar = 80 μm