Fig. 8

Overexpression of circLHFPL2 improved sensitivity of MEK inhibitors in CRC cells with PIK3CA mutations. A Western blotting showed the protein expression level of P-gp and BCRP in HCT116 and DLD1 cells with or without PIK3CA mutation, transfected with circLHFPL2 overexpression plasmid or empty vector. B Western blotting showed the protein expression of P-gp and BCRP in CRC tissues with or without PIK3CA mutations. C Tissue microarray (TMA) analysis for P-gp and BCRP expression in 30 PIK3CA-mutant and 30 PIK3CA non-mutant CRC tissues by immunohistochemistry. D CCK-8 assay revealed the viability of PIK3CA^H1047R and PIK3CA^E545K cells transfected with circLHFPL2 overexpression plasmid or with empty vector treatment with AZD6244 or RDEA119 for 24 h (inhibitor concentration: 0.01, 0.1, 1, 5, 10 μM). Black arrow indicates IC50 value. E and F AZD6244 inhibited the growth of xenografted tumors of HCT116 PIK3CA^H1047R (E) and WT (F) cells. Overexpression of circLHFPL2 enhanced the tumor sensitivity to AZD6244 especially in PIK3CA-mutant tumors. 10 mg/kg of AZD6244 was injected intraperitoneally every 3 days. Data are presented as mean ± SEM; n ≥ 3