BACKGROUND: The clinical efficacies of anticancer drugs are limited by non-selective toxic effects on healthy tissues and low bioavailability in tumor tissue. Therefore, the development of vehicles that can selectively deliver and release drugs at the tumor site is critical for further improvements in patient survival.
METHODS: We prepared a CEC nano-drug delivery system, CEC@ZIF-8, with a zeolite imidazole framework-8 (ZIF-8) as a carrier, which can achieve the response of folate receptor (FR). We characterized this system in terms of morphology, particle size, zeta potential, infrared (IR), x-ray diffraction (XRD), and transcriptome analysis, and examined the in vitro cytotoxicity and cellular uptake properties of CEC@ZIF-8 using cervical cancer cells. Lastly, we established a TC-1 tumor-bearing mouse model and evaluated its in vivo anti-cervical cancer activity.
RESULTS: The CEC@ZIF-8 nano-delivery system had favorable biocompatibility, heat stability, and pH responsiveness, with a CEC loading efficiency of 12%, a hydrated particle size of 174 ± 5.8 nm, a zeta potential of 20.57 mV, and slow and massive drug release in an acidic environment (pH 5.5), whereas release was 6% in a neutral environment (pH 7.4). At the same time, confocal imaging and cell viability assays demonstrated greater intracellular accumulation and more potent cytotoxicity against cancer cells compared to free CEC. The mechanism was analyzed by a series of transcriptome analyses, which revealed that CEC@ZIF-8 NPs differentially regulate the expression levels of 1057 genes in cancer cells, and indicated that the enriched pathways were mainly cell cycle and apoptosis-related pathways via the enrichment analysis of the differential genes. Flow cytometry showed that CEC@ZIF-8 NPs inhibited the growth of HeLa cells by arresting the cell cycle at the G0/G1 phase. Flow cytometry also revealed that CEC@ZIF-8 NPs induced greater apoptosis rates than CEC, while unloaded ZIF-8 had little inherent pro-apoptotic activity. Furthermore, the levels of reactive oxygen species (ROS) were also upregulated by CEC@ZIF-8 NPs while ROS inhibitors and caspase inhibitors reversed CEC@ZIF-8 NPs-induced apoptosis. Finally, CEC@ZIF-8 NPs also reduced the growth rate of xenograft tumors in mice without the systemic toxicity observed with cisplatin treatment.
CONCLUSIONS: The CEC@ZIF-8 nano-drug delivery system significantly enhanced the anti-cervical cancer effect of CEC both in vivo and in vitro, providing a more promising drug delivery system for clinical applications and tumor management. At the same time, this work demonstrates the clinical potential of CEC-loaded ZIF-8 nanoparticles for the selective destruction of tumor tissues.
