Fig. 1: Observation of STAT3 mRNA localization in HCCLM3 protrusions.

a Schematic diagram of Boyden chamber. Cells were placed in the upper chamber with a 1-μm pore size microporous membrane, only allowing the migration of cells prominent to the lower chamber. b RT-PCR analysis shows that STAT3α, rather than STAT3β, is primarily expressed in the cell protrusions c Fluorescence in situ hybridization (FISH) detection to indicate the localization of STAT3 mRNA in HCCLM3 cells. Scale bar: 100 μm. d Representative images of STAT3 by immunohistochemical (IHC) staining showing high STAT3 expression in carcinoma tissues (left panel) versus non-carcinoma tissues (right panel) (scale bar: 25 μm (in the enlarged image), n = 21 biologically independent samples). Interestingly, STAT3 was mainly gathered in the nucleus (indicated by red arrow, left panel) in carcinoma tissues whereas scattered on the edge of the cell membrane in non-carcinoma tissues (indicated by red arrow, right panel). e Statistics of average optical density of STAT3 in d. f Analysis of STAT3 expression in 20 metastatic HCC tissues versus counterpart non-metastatic tissues in GEO dataset (GSE28248). g Stable knockdown of STAT3 in HCCLM3 cells by lentiviral shRNA sequences (shSTAT3). The knockdown effect was verified at both the mRNA and protein levels. h–j STAT3 depletion obviously inhibited the migration (h, i) and invasion (j) of HCCLM3 cells. Scale bar: 100 μm. The values in the graphs represent the mean of three biologically independent experiments. Error bars represent ±s.d. *P < 0.05, **P < 0.01, ***P < 0.001 by two-tailed Student’s t-test.