Fig. 2
Specific knockdown of HER3 expression markedly inhibits TNBC cell proliferation and mammosphere formation in vitro and profoundly suppresses TNBC tumor growth in vivo. A and B, HCC1806, MDA-MB-468 (MDA-468), and MDA-MB-231 (MDA-231) cells were infected with lentivirus containing either control shRNA (shControl) or specific shRNA against HER3 (shHER3) for 24 h. The cells were then seeded in 96-well plates, incubated at a regular cell culture incubator, and monitored for growth via an IncuCyte system for 64 h. The cell growth curves were generated by GraphPad Prism9 software with the data obtained through IncuCyte scanning every 4 h (A). The cells were then subjected to mammosphere formation assays. After 14 days, representative images of the mammospheres were shown and the number and size of those mammospheres were examined, quantified, and presented in the bar graphs (B). Data shows a representative of three independent experiments. Bars, SD. *, p < 0.05, **, p < 0.01, ***, p < 0.005. C, Luciferase-labelled HCC1806 cells were infected with lentivirus containing either control shRNA (shControl) or HER3 shRNA (shHER3) for 24 h. The HCC1806-shControl or HCC1806-shHER3 cells (5 × 105) were orthotopically inoculated into the left or right mammary fat pads of female nude mice, respectively (n = 4). In vivo bioluminescent imaging of the mammary tumors was obtained with the IVIS spectrum at day 1, 7, or 14 after cell inoculation. The graph showed the luciferase signal intensity of the mammary tumors obtained from the mice injected with HCC1806-shControl or HCC1806-shHER3 cells at day 1 and 14. A significant difference was observed using a two-sided Student’s t-test