To improve the efficiency of insulin via oral administration, pH-sensitive carboxylated chitosan grafted poly(methyl methacrylate) nanoparticles (CCGN) were prepared. CCGN were characterized by (1)H NMR, dynamic light scattering, zeta potential, and transmission electron microscopy, and the hypoglycemic effect of insulin loaded CCGN via the oral route was evaluated in normal and diabetic rats. CCGN exhibited a homogeneous morphology and a spherical shape with core-shell structure. They were aggregated in simulated gastric fluid while separated in simulated intestinal fluid. Insulin was mainly located in the shell of the CCGN via hydrogen bonding, electrostatic interaction, and Van der Waals force. Insulin release from the CCGN exhibited a pH-sensitive property in that it had a slow release rate at pH 2.0 and a fast release rate at pH 6.8 and 7.4. The pharmacological bioavailability after oral administration of insulin loaded CCGN at a dose of 25 IU/kg was found to be 9.7%. Besides, CCGN showed desirable tissue and blood compatibility. Therefore, the CCGN would be a promising delivery carrier for protein drugs via the oral route.

Matrix metalloproteinases (MMPs) have been regarded as major critical molecules assisting tumor cells during metastasis, for excessive ECM (ECM) degradation, and cancer cell invasion. In the present study, in vitro and in vivo assays were employed to examine the inhibitory effects of kaempferol, a natural polyphenol of flavonoid family, on tumor metastasis. Data showed that kaempferol could inhibit adhesion, migration, and invasion of MDA-MB-231 human breast carcinoma cells. Moreover, kaempferol led to the reduced activity and expression of MMP-2 and MMP-9, which were detected by gelatin zymography, real-time PCR, and western blot analysis, respectively. Further elucidation of the mechanism revealed that kaempferol treatment inhibited the activation of transcription factor activator protein-1 (AP-1) and MAPK signaling pathway. Moreover, kaempferol repressed phorbol-12-myristate-13-acetate (PMA)-induced MMP-9 expression and activity through suppressing the translocation of protein kinase Cδ (PKCδ) and MAPK signaling pathway. Our results also indicated that kaempferol could block the lung metastasis of B16F10 murine melanoma cells as well as the expression of MMP-9 in vivo. Taken together, these results demonstrated that kaempferol could inhibit cancer cell invasion through blocking the PKCδ/MAPK/AP-1 cascade and subsequent MMP-9 expression and its activity. Therefore, kaempferol might act as a therapeutic potential candidate for cancer metastasis.

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Novel chitosan derivatives carrying linoleic acid (LA) as hydrophobic moieties and poly(beta-malic acid) (PMLA) as hydrophilic moieties (LA/PMLA double grafted chitosan, LMC) were synthesized. It self-assembled into nanoparticles of 190-350 nm in water, which carried negative surface charges in physiological pH. The critical aggregation concentration of the LMC deceased with an increase in the LA content. Paclitaxel (PTX) was loaded into the LMC nanoparticles with a high loading efficiency and the maximum loading capacity of 9.9 +/- 0.4%. PTX-LMC nanoparticles exhibited a sustained release within 24 h in pH 7.4 phosphate-buffered saline (PBS), and the release rate was affected by the LA content and PMLA length. Hemolysis and acute toxicity assessment indicated that the LMC nanoparticles were safe drug carriers for i.v. administration. Additionally, PTX-LMC showed significantly potent tumor inhibition efficacy relative to that of TAXOL in S-180 bearing mice. Therefore, the LMC nanoparticles could be an effective and safe vehicle for systemic administration of hydrophobic drugs, especially PTX.

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