Fig. 6: Inhibition of c-myc sensitizes breast cancer cells to palbociclib in vivo.

Empty vector or shMyc were transfected into MDA-MB-231 cells, which were injected into nude mice, respectively. Mice bearing MDA-MB-231 xenografts with a tumor volume of 100 mm³ (6 for each group) was then randomly grouped and treated with vehicle (orally), or palbociclib at a dose of 100 mg/kg twice a week by oral gavage. a Visualization of the mice and tumors, after 21 days of initial treatment. b Tumor volumes were calculated every 3 days. c The qRT-PCR was performed to detect the average expression miR-29b-3p in xenograft tumors. d Western blot analysis of c-myc and CDK6 in xenograft tumors. GAPDH was used as an internal control. e The tumors were removed from the mice in 21 days after drug treatment ended, and immunohistochemical staining for CDK6, c-myc, and Ki-67 were conducted. Expression ratio of CDK6, c-myc, and ki67 in each of the treatment arms are shown. f Immunohistochemical staining of c-myc and Ki-67 in patient-derived tumor xenograft (PDX) model of patient 2 and 5. g The positive stained cells of Ki-67 before and after palbociclib treatment in all eight PDX models. Error bars indicate mean ± SD.