In recent years, metal organic frameworks (MOFs) have been widely developed as vehicles for the effective delivery of drugs to tumor tissues. Due to the high loading capacity and excellent biocompatibility of MOFs, they provide an unprecedented opportunity for the treatment of cancer. However, drugs which are commonly used to treat cancer often cause side effects in normal tissue accumulation. Therefore, the strategy of drug targeting delivery based on MOFs has excellent research significance. Here, we introduce several intelligent targeted drug delivery systems based on MOFs and their characteristics as drug-loading systems, and the challenges of MOFs are discussed. This article covers the following types of MOFs: Isoreticular Metal Organic Frameworks (IRMOFs), Materials of Institute Lavoisier (MILs), Zeolitic Imidazolate Frameworks (ZIFs), University of Oslo (UiOs), and MOFs-based core-shell structures. Generally, MOFs can be reasonably controlled at the nanometer size to effectively achieve passive targeting. In addition, different ligands can be modified on MOFs for active or physicochemical targeting. On the one hand, the targeting strategy can improve the concentration of the drugs at the tumor site to improve the efficacy, on the other hand, it can avoid the release of the drugs in normal tissues to improve safety. Despite the challenges of clinical application of MOFs, MOFs have a number of advantages as a kind of smart delivery vehicle, which offer possibilities for clinical applications.

A MIL series metal‒organic framework (MOF), MIL-100(Fe), was successfully synthesized at the nanoscale and fully characterized by TEM, TGA, XRD, FTIR, DLS, and BET. A toxicological assessment was performed using two different cell lines: human normal liver cells (HL-7702) and hepatocellular carcinoma (HepG2). In vitro cytotoxicity of MIL-100(Fe) was evaluated by the MTT assay, LDH releasing rate assay, DAPI staining, and annexin V/PI double staining assay. The safe dose of MIL-100(Fe) was 80 μg/mL. It exhibited good biocompatibility, low cytotoxicity, and high cell survival rate (HL-7702 cells’ viability >85.97%, HepG2 cells’ viability >91.20%). Therefore, MIL-100(Fe) has a potential application as a drug carrier.

Hepatocellular carcinoma (HCC) is one of the most common cancers with the highest morbidity and mortality. It is necessary to develop new anti-liver cancer drugs. Itraconazole is a popular systemic anti-fungal drug with a strong anti-tumor effect. However, so far, it is not clear whether itraconazole has specific anti-tumor effect on liver cancer. The purpose of this study was to investigate itraconazole resistant effect of liver cancer and to explore its potential anti-cancer mechanism. The effect of itraconazole on the proliferation of liver cancer cells was studied with MTT assay. Flow cytometry was used to determine the effect of itraconazole on apoptosis, cell cycle distribution, changes in intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). In addition, after DAPI staining, nuclear morphological changes were observed under the fluorescent microscope, and the release of lactate dehydrogenase (LDH) was measured using the microplate reader. Finally, the expressions of proteins related to the anti-tumor signaling pathway were determined by Western blotting. The results showed that itraconazole significantly inhibited the proliferation of HepG2 and Bel-7405 cells. In addition, the data showed that itraconazole induced apoptosis in HepG2 cells, increased the production of ROS, blocked cell cycle, and decreased MMP. Furthermore, itraconazole inhibited HCC cell growth and promoted apoptosis through the Hh, Wnt/catenin, AKT/mTOR/S6K, ROS and death receptor pathways. Finally, we come to the conclusion that itraconazole exerts anti-liver cancer effect, and has potential for use as a new drug for liver cancer in clinic.

Emodin is the main component of traditional Chinese medicines including rhubarb, Polygonum multiflorum, and Polygonum cuspidatum. It has confirmed hepatotoxicity and may be the main causative agent of liver damage associated with the above-mentioned traditional Chinese medicines. However, current research does not explain the mechanism of emodin in hepatotoxicity. In this study, L02 cells were used as a model to study the mechanism of emodin-induced hepatocyte apoptosis using quantitative proteomics, and the results were verified by Western blot. A total of 662 differentially expressed proteins were discovered and analyzed using Gene Ontology (GO) and pathway enrichment analysis. The results show that the oxidative phosphorylation pathway is highly represented. Abnormalities in this pathway result in impaired mitochondrial function and represent mitochondrial damage. This result is consistent with mitochondria membrane potential measurements. Analysis of differentially expressed proteins revealed that emodin mainly affects oxidative phosphorylation pathways by inhibiting the function of the mitochondrial respiratory chain complexes; the mitochondrial respiratory chain complex activity assay result also confirmed that emodin could inhibit the activity of all mitochondrial complexes. This results in an increase in caspase-3, a decrease in mitochondrial membrane potential (MMP,) an increase in reactive oxygen species (ROS), and disorders in ATP synthesis, etc., eventually leading to mitochondrial damage and hepatocyte apoptosis in vitro.

Curcumin (Cur) is a naturally hydrophobic polyphenol with potential pharmacological properties. However, the poor aqueous solubility and low bioavailability of curcumin limits its ocular administration. Thus, the aim of this study was to prepare a mixed micelle in situ gelling system of curcumin (Cur-MM-ISG) for ophthalmic drug delivery. The curcumin mixed micelles (Cur-MMs) were prepared via the solvent evaporation method, after which they were incorporated into gellan gum gels. Characterization tests showed that Cur-MMs were small in size and spherical in shape, with a low critical micelle concentration. Compared with free curcumin, Cur-MMs improved the solubility and stability of curcumin significantly. The ex vivo penetration study revealed that Cur-MMs could penetrate the rabbit cornea more efficiently than the free curcumin. After dispersing the micelles in the gellan gum solution at a ratio of 1:1 (v/v), a transparent Cur-MM-ISG with the characteristics of a pseudoplastic fluid was formed. No obvious irritations were observed in the rabbit eyes after ocular instillation of Cur-MM-ISG. Moreover, Cur-MM-ISG showed a longer retention time on the corneal surface when compared to Cur-MMs using the fluorescein sodium labeling method. These findings indicate that biocompatible Cur-MM-ISG has great potential in ophthalmic drug therapy.

Phillyrin Mitigates Apoptosis and Oxidative Stress in Hydrogen Peroxide-Treated RPE Cells through Activation of the Nrf2 Signaling Pathway: Oxidative stress-induced dysfunction or apoptosis in retinal pigment epithelial (RPE) cells is an important cause of dry age-related macular degeneration (AMD). Although phillyrin has been shown to exert significant antioxidant effects, the underlying mechanism of action remains unclear. The purpose of this study was to investigate the protective effect of phillyrin on hydrogen peroxide- (H₂O_2-) induced oxidative stress damage in RPE cells and the potential mechanism involved. It was found that phillyrin significantly protected RPE cells from H₂O₂ cytotoxicity. Furthermore, phillyrin alleviated oxidative stress-induced apoptosis via inhibition of endogenous and exogenous apoptotic pathways. Compared with the H₂O₂-treated group, the expressions of cleaved caspase-3, cleaved caspase-9, cleaved polymerase (PARP), death receptor Fas, and cleaved caspase-8, as well as Bax/Bcl-2 ratio were decreased in RPE cells after the phillyrin intervention. In addition, phillyrin reversed the oxidative stress-induced reductions in superoxide dismutase (SOD) and glutathione (GSH) levels and annulled the elevations in reactive oxygen species (ROS) and malondialdehyde (MDA), thereby restoring oxidant-antioxidant homeostasis. Phillyrin treatment upregulated the expressions of cyclin E, cyclin-dependent kinase 2 (CDK2), and cyclin A and downregulated the expressions of p21 and p-p53, thereby reversing the G0/G1 cell cycle arrest in H₂O₂-treated RPE cells. Pretreatment with phillyrin also increased the expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2), total Nrf2, heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductases-1 (NQO-1) in RPE cells and inhibited the formation of Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 protein complex. Thus, phillyrin effectively protected RPE cells from oxidative stress through activation of the Nrf2 signaling pathway and inhibition of the mitochondria-dependent apoptosis pathway.