Fig. 6: STK4 is negatively related to HCC severity via activating Hippo signaling.

A–C SKT4 expression was detected in HCC tumors and peri-tumors (A), oncospheres and non-spheres (B), as well as liver CSCs and non-CSCs (C). n = 3 independent experiments. Results are shown as means ± SD. Exact P values from left to right A: 0.0406, 0.0115, 0.0063, 0.0027, 0.036, 0.0104. Exact P values from left to right B: 0.0063, 0.0069, 0.0003, 0.013, 0.0025. Exact P values from left to right C: 0.022, 0.003, 0.031, 0.029, 0.0037. D Immunohistochemistry with anti-MST1 antibody was performed in HCC samples. Scale bar, 400 μm. E Expression levels of SKT4 in HCC samples provided by Wang’s cohort (GSE14520). F 1 × 10⁶ STK4 depleted or control cells were subcutaneously injected into BALB/c nude mice, followed by measurement of tumor parameters every 4 days. n = 3 for each group. Results are shown as means ± SD. Exact P values from left to right: 0.00062, 0.00126, 0.027, 0.016. G Immunohistochemistry with YAP antibody was performed in human HCC samples. Scale bars, 75 μm. H Expression levels of MST1, pMST1, and pYAP1 were examined by Western blotting in HCC tumors and peri-tumors. I STK4 deficiency rescued the impaired sphere-formation capacity, which was caused by SNORD88B ASO2. Representative images (upper panel) and statistical results (lower panel) are shown. Scale bar, 500 μm. n = 3 independent experiments. Results are shown as means ± SD. Exact P values from left to right: 0.0005, 0.023, 2.82E−05, 0.002. J Western blot analysis showed that SNORD88B overexpression remarkably reduced YAP1 phosphorylation, which could be rescued by overexpression of MST1. K Localization of YAP1 in SNORD88B knockdown or control liver CSCs was analyzed by immunofluorescence staining. Scale bars, 40 μm. *P < 0.05; **P < 0.01; ***P < 0.001 by two-tailed Student’s T-test. Data are representative of at least three independent experiments.