Figure 1: RAF1 is expressed at low levels in human HCC and suppresses the growth of both HCC xenografts and chemically induced tumours.
From: A cell-autonomous tumour suppressor role of RAF1 in hepatocarcinogenesis
(a) RAF1 expression in a cohort of 31 HCC patients. Left panel, representative IHC image (T, tumour; NT, non-tumour). Scale bar, 50 μm. Middle panel, RAF1 expression in matched tumour and non-tumour tissue (a.u.=arbitrary units). Right panel, RAF1 expression in tumours correlates inversely with tumour grade (ratio: protein expression in tumour/non-tumour tissue). (b) Inducible shRNA-mediated RAF1 silencing does not impact A- or BRAF expression (top panel) but increases the proliferation of Hep3B cells in culture (bottom panel; n=6). (c) Inducible shRNA-mediated RAF1 silencing strongly promotes the growth of Hep3B xenografts. (d,e) Ablation of RAF1 in liver parenchymal cells promotes chemically induced hepatocarcinogenesis. Top panels, experimental protocols. Left bottom panel, macroscopic appearance of F/F and Δhep (d) or Δp/np (e) tumour-bearing livers 30 weeks (w) after DEN injection; arrows indicate tumours. Scale bars, 0.5 cm. Middle panels, liver:body weight ratio of untreated or DEN/Pb-treated mice. Right panels, tumour numbers and % of tumour-occupied area in control, Δhep (d) and Δp/np (e) livers. In (d), no DEN: F/F n=4, Δhep=6; DEN-treated: F/F n=7, Δhep=8. In (e), DEN-treated: F/F n=10, Δp/np n=11. (f,g) Quantification of Ki67+ cells: (f) and inflammatory cells (g; F4/80+ cells, granulocytes and CD3+ cells) in tumour-bearing F/F and Δhep livers. Np=non-parenchymal cells. (h) Chemokine levels in the serum of F/F and Δhep mice. (i) Chemo-/cytokine levels in tumour-bearing livers. Data are presented as mean ± SEM, *P≤0.05, **P<0.01, ***P<0.005. In the box and whiskers plots (Tukey method), the box represents interquartile range, the middle bar the median, and the whiskers extend to 1.5 times the interquartile range. In (a), non-tumour versus tumour comparisons were analysed using paired Wilcoxon signed-rank test. P values are indicated in the graph (middle panel); in the right panel data were analysed using Spearman correlation. Spearman's rank correlation coefficient (rs) and P values are indicated within the graph. See also Supplementary Figs 1 and 2 and Supplementary Tables 1 and 2.
