pH-Responsive Artesunate Polymer Prodrugs with Enhanced Ablation Effect on Rodent Xenograft Colon Cancer.

PURPOSE: In this study, pH-sensitive poly(2-ethyl-2-oxazoline)-poly(lactic acid)-poly(ß-amino ester) (PEOz-PLA-PBAE) triblock copolymers were synthesized and were conjugated with an antimalaria drug artesunate (ART), for inhibition of a colon cancer xenograft model. METHODS: The as-prepared polymer prodrugs are tended to self-assemble into polymeric micelles in aqueous milieu, with PEOz segment as hydrophilic shell and PLA-PBAE segment as hydrophobic core. RESULTS: The pH sensitivity of the as-prepared copolymers was confirmed by acid-base titration with pKb values around 6.5. The drug-conjugated polymer micelles showed high stability for at least 96 h in PBS and 37°C, respectively. The as-prepared copolymer prodrugs showed high drug loading content, with 9.57%±1.24% of drug loading for PEOz-PLA-PBAE-ART4. The conjugated ART could be released in a sustained and pH-dependent manner, with 92% of released drug at pH 6.0 and 57% of drug released at pH 7.4, respectively. In addition, in vitro experiments showed higher inhibitory effect of the prodrugs on rodent CT-26 cells than that of free ART. Animal studies also demonstrated the enhanced inhibitory efficacy of PEOz-PLA-PBAE-ART2 micelles on the growth of rodent xenograft tumor. CONCLUSION: The pH-responsive artesunate polymer prodrugs are promising candidates for colon cancer adjuvant therapy.

[Preparation of docetaxel-loaded nanomicelles and their anti-Lewis lung cancer effect in vitro].

Docetaxel-loaded nanomicelles were prepared in this study to improve the solubility and tumor targeting effect of docetaxel(DTX),and further evaluate their anticancer effects in vitro. PBAE-DTX nanomicelles were prepared by film-hydration method with amphiphilic block copolymer polyethyleneglycol methoxy-polylactide(PELA) and pH sensitive triblock copolymer polyethyleneglycol methoxy-polylactide-poly-ß-aminoester(PBAE) were used respectively to prepare PELA-DTX nanomicelles and PBAE-DTX nanomicelles. The nanomicelles were characterized by physicochemical properties and the activity of mice Lewis lung cancer cells was studied. The results of particle size measurement showed that the blank micelles and drug-loaded micelles had similar particle sizes, ranging from 10 to 100 nm. The particle size of PBAE micelles was changed under weak acidic conditions, with good pH response. The encapsulation efficiency of the above two types of DTX-loaded nanomicelles determined by HPLC was(93.8±1.70)% and(87.2±4.10)%, and the drug loading amount was(5.3±0.10)% and(4.9±0.05)%,respectively. Furthermore,the DTX micelles also showed significant inhibitory effects on Lewis lung cancer cells by MTT assay, and pH-sensitive PBAE-DTX showed better cytotoxicity. The results of flow cytometry indicated that,the apoptosis rate of lung cancer Lewis cells was(20.72±1.47)%,(29.71±2.38)%,and(40.91±1.90)%(P<0.05) at 48 h after treatment in DTX,PELA-DTX,and PBAE-DTX groups. The results showed that different docetaxel preparations could promote the apoptosis of Lewis cells, and PBAE-DTX had stronger apoptotic-promoting effect. The pH-sensitive DTX-loaded micelles are promising candidates in developing stimuli triggered drug delivery systems in acidic tumor micro-environments with improved inhibitory effects of tumor growth on Lewis lung cancer.