Extended Data Figure 6 : Competitive advantage of SOX2–GFP+ cells and inefficient reversibility of SOX2 expression during tumour transplantation.

From: SOX2 controls tumour initiation and cancer stem-cell functions in squamous-cell carcinoma

Extended Data Figure 6

a, Scheme summarizing the experimental strategy used to define the tumour-propagating capacities of SOX2–GFP+ and GFP TEC populations during serial transplantations of DMBA/TPA-induced SCCs. b, FACS analysis of SOX2–GFP and CD34 within the TEC population in a representative primary SCC. c, Co-immunostaining for K14 (white), CD34 (green) and SOX2 (red) in a primitive mouse skin SCC and tumours arising following the serial transplantation of SOX2–GFP+ TECs, showing the increased proportion of cells expressing SOX2 after serial transplantation. d, Scheme representing the strategy used to measure enrichment of SOX2–GFP+ TECs during serial transplantations. Epcam+ TECs were FACS isolated from primary SCCs, primary (1st graft) and secondary grafts (2nd graft) using co-staining for Epcam and Lin. e, Representative FACS plots of SOX2–GFP+ expression in Epcam+/Lin TECs from SCC, 1st and 2nd grafts. These data show that the proportion of SOX2–GFP+ TECs increases over serial transplantation. f, Quantification of the proportion of SOX2–GFP+ cells in TECs from primary SCCs (n = 6), 1st graft (n = 7) and 2nd graft (n = 13). Analysis of variance was performed (P < 0.0001) followed by Tukey test for comparison of each pair of conditions. g, Scheme representing the strategy and FACS analysis used to measure reversibility of SOX2–GFP+ and SOX2–GFP TECs upon transplantation. TECs were sorted based on SOX2–GFP expression from primary tumour (SCC) and primary (1st) graft, using co-staining for Epcam, SOX2–GFP and Lin. h, FACS quantification of the proportion of SOX2–GFP+ cells in the primary graft from SOX2–GFP+ and SOX2–GFP tumours. (n = 5 tumours from 5 mice for each group). i, j, Co-immunostaining for K14 (red) and GFP (green) (i) and for K14 (green) and SOX2 (red) (j) in primary tumours arising from transplantation of SOX2–GFP+ or SOX2–GFP TECs, showing the inefficient reversibility of SOX2-negative cells into SOX2-positive cells. Hoechst nuclear staining is represented in blue. Scale bars, 50 μm. Data represent the mean and s.e.m. NS, not significant.