A. Levels of CD147 mRNA in 23 HCC tissue (T) and adjacent non-cancerous tissue (N) were measured by qRT-PCR. B, C. Expression of CD147 in HCC cell lines (SMMC-7721, Huh-7, HepG2, PLC/PRF/5, and Hep3B) and normal hepatocytes (QSG-7701) was measured by qRT-PCR (B) and western blot (C). D, E. CD147 overexpression was confirmed by qRT-PCR (D) and western blot (E). F. CD147 overexpression increases proliferation in PLC/PRF/5, Hep3B, and HepG2 cells. G. CD147 overexpression increases the resistance of PLC/PRF/5, Hep3B, and HepG2 cells to cytotoxic chemotherapy. H, I. CD147 knockdown was confirmed by qRT-PCR (H) and western blot (I). J, K. Knockdown of CD147 inhibits cell proliferation (J) and decreases resistance to cytotoxic chemotherapy (K). Cell proliferation was measured using CCK-8 assays at 96 (F, J) and 48 hours (G, K). Cells were treated with doxorubicin (1 μg/mL), etoposide (10 μg/mL), and fluorouracil (5-FU; 100 μg/mL) for 2 days. Relative cell viability is shown as the fold change compared to mock control cells (G, K). GAPDH was used as a loading control in (C), (E), and (I). The qRT-PCR data in (A), (B), (D), and (H) were normalized to 18S RNA and are shown as the fold change relative to QSG-7701 cells in (B), EV groups in (D), and sh-Ctrl groups in (H). EV, empty vector. Sh-Ctrl, scramble shRNA vector control. All experiments were repeated three times. The bars represent the mean ± S.D. (n = 3), *p < 0.05, **p < 0.01.