Fig. 7: PPP3CB/FOXO3a/IRS1 signaling contributed to poor response to Herceptin in vivo.
a Pool2/sh-Con or pool2/sh-IRS1 cells were subcutaneously inoculated into the armpit of female Balb/C athymic nude mice to generate tumor xenografts. When the tumor size reached ~100 mm3, the mice were randomly grouped and received intraperitoneal (i.p.) injection of PBS or Herceptin (10 mg/kg) (n = 5) once every 5 days. The tumor growth was measured every 5 days (left). At the experimental endpoint, the tumor weights were measured (right), ****p < 0.0001. b Pool2 cells with control sgRNA vector (sg-Con) or IRS1 gene specific sgRNA (sg-IRS1) were subcutaneously inoculated into the armpit of female Balb/C athymic nude mice to generate xenograft tumors. When the tumor sizes reached ~100 mm3, the mice were randomly grouped and received i.p. injection of Herceptin (10 mg/kg) or PBS (n = 5) once every 5 days. The tumor growth was measured every 5 days (left). At the experimental endpoint, the tumor weights were measured (right), ****p < 0.0001. c, d The serum and tumor tissues were obtained from 23 HER2-positive breast cancer patients with a good response to Herceptin-containing treatments and 17 HER2-positive breast cancer patients with a poor response to Herceptin-containing treatments. The levels of IGF2 in the serum were detected by ELISA (c), ****p < 0.0001; The expression of IRS1, PPP3CB, and p-FOXO3a in the tumors was examined by Immunohistochemistry (IHC) assays (d). Data are presented as mean values ± SEM (c). Statistical significance was determined by a two-tailed Student’s t-test (a–c). e Kaplan–Meier analyses of overall survival (OS), relapse-free survival (RFS), and distant metastasis-free survival (DMFS) in breast cancer patients with low versus high expression of PPP3CB. The survival curves were shown with the hazard ratio with 95% confidence intervals and logrank P-values.
