Fig. 5

Combined treatment of palbociclib and PEG10-ASO regresses the palbociclib-resistant breast cancer synergistically in a xenograft model. A Experimental design for in vivo efficacy test using acquired palbociclib-resistant xenograft model in BALB/c nude mice. When tumor reached 60–80 mm3, mice were randomized to control-ASO (n = 5), palbociclib (n = 5), PEG10-ASO (n = 5), and combination (n = 5) treatment groups. Control-ASO and PEG10-ASO were administrated intraperitoneally (i.p.) for 3 weeks (15 mg/kg/day for first 5 days loading, followed by 17 days of maintenance dose of 15 mg/kg, 3 times/week). Palbociclib (100 mg/kg/day) was given by oral gavage for 3 weeks. B Gross harvested tumor. The black dotted circles represent the complete regression of the tumor. C Average tumor sizes of the indicated treatment groups before sacrifice. Independent sample t-test: ***p < 0.001, Abbreviation: ns, not significant. D Average tumor growth of MCF7-PR xenograft tumor treated with indicated drugs. Error bars represent SD of 5 tumors per group. Independent sample t-test: ***p < 0.001, Abbreviation: ns, not significant. E Average body weight of mice with indicated groups. Error bars represent the SD of 5 mice per group. F Immunoblots using xenograft tumors showed the suppression of PEG10 in the PEG10-ASO and combination treatment groups, along with altered ZEB1 and E-cadherin expression. G IHC staining of PEG10 in MCF7-PR xenograft tumors of indicated groups. Staining images were taken at 400 × magnification. The bar graph represented the PEG10 protein expression in five random, non-overlapped fields. Data are presented as mean ± SD. Independent sample t-test: ***p < 0.001, Abbreviation: ns, not significant. H IHC staining of Ki67 in MCF7-PR xenograft tumors of indicated groups. Staining images were taken at 400 × magnification. The bar graph represented the Ki67 cells in five random, non-overlapped fields. Data are presented as mean ± SD. Independent sample t-test: *p < 0.05, ***p < 0.001. I TUNEL assay using xenograft tumors at sacrifice. Staining images in each group are shown and bar graphs represent average apoptotic cells in each group in five random, non-overlapped fields at 400 × magnification. Data are presented as mean ± SD. Independent sample t-test: **p < 0.01, ***p < 0.001, Abbreviation: ns, not significant