The polylactic-co-glycolic acid polyethylene glycol conjugated with cell penetrating peptide R7 (PLGA–PEG-R7)/polysulfadimethoxine-folate nanoparticles loaded with docetaxel (DTX) and GDC0941 (R7/PSD-Fol NPs) were prepared to overcome multidrug resistance (MDR) and enhance the antitumor activity. First, polysulfadimethoxine-folate was synthesized to construct the R7/PSD-Fol NPs. The R7/PSD-Fol NPs were prepared with the abilities of effective entrapment and drug loading. Due to the pH-sensitive effect of PSD-folate, the releasing of DTX and GDC0941 from the R7/PSD-Fol NPs was lower in pH 7.4 buffer solution than that in pH 5.0 buffer solution. The half maximal inhibitory concentration (IC50) of MCF-7 and resistant to doxorubicin (MCF-7/Adr) cells illustrated the cytotoxicity of R7/PSD-Fol nanoparticles by using the MTT method. The uptake of R7/PSD-Fol NPs was visualized by using the fluorescence of Rh-123 to detect the targeting effect of folate on the surface of R7/PSD-Fol NPs. The results of the cell apoptosis and the depolarization of mitochondrial membrane potential (MMP) were adopted to show the cytotoxicity of the R7/PSD-Fol NPs on MCF-7/Adr cells. The Western blot revealed the inhibition of PI3K/Akt pathway in MCF-7/Adr cells induced by R7/PSD-Fol NPs. Finally, both in vivo distribution and in vivo antitumor showed the R7/PSD-Fol NPs displayed the better distribution at tumor site and the stronger suppression of tumor growth in the tumor bearing nude mice compared with control group. It was concluded that R7/PSD-Fol NPs loaded with DTX and GDC0941 could overcome MDR and enhance the antitumor effect further.
Docetaxel (DTX) is one kind of well-known anticancer drugs against tumors. GDC0941 was used to inhibit PI3K/Akt signal pathway and improve anti-tumor activity. PLGA-PEG-R7 (poly lactic-co-glycolic acid polyethylene glycol bending with cell penetrating peptide R7)/poly sulfadimethoxine-Folate nanoparticles (R7/PSD-Fol NPs) were made to load DTX and GDC0941 simultaneously. In vitro, the release capacity of DTX and GDC0941 inside nanoparticles was determined and both drugs could release from nanoparticles to 70% within 48h. The result of flow cytometry showed that GDC0941 had no interference on cell uptake and R7/PSD-Fol NPs could enhance MCF-7 cells uptake the most significantly. In cell colony study, GDC0941 could further improve the anti-tumor effect of DTX and inhibit the formation of cell clones on the basis of enhancing the uptake of R7/PSD-Fol NPs. The capability of cell colony formation was as follows: DTX > DTX + GDC0941 > R7 NPs > R7/PSD-Fol NPs. The expression of cell apoptosis proteins treated with R7/PSD-Fol NPs was the lowest. The addition of GDC0941 could decrease the full-length content of apoptotic proteins caspase-3 and caspase-9. In vivo, pharmacokinetic parameters results showed us that GDC0941 had no interference on pharmacokinetic study. Main pharmacokinetic parameters of DTX suspension and R7/PSD-Folate NPs suspension showed significant differences.
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