A G2/M-phase specific drug delivery system based on increased exposure of phosphatidylethanolamine on mitotic cancer cells and low pH in tumor tissues

Dual-modified starch micelles as a promising nanocarrier for doxorubicin

Natural amphiphilic polymer micelles have garnered considerable research attention as nanocarriers for delivering drugs. The objective of this study was to explore the possibility of applying biocompatible dual-modified starch micelles as drug delivery vehicles. To this end, a dual-modified corn starch polymer (SCD) was synthesized with zwitterionic sulfobetaine and deoxycholic acid; spherical micelles with an average particle size of ~200 nm were prepared through the self-assembly of SCD. The effects of dual modification on the degree of substitution, molecular structure, and functional properties of SCD were investigated. Further, doxorubicin was successfully incorporated into the micelles, and an in vitro drug release study was performed to confirm that the drug-loaded micelles displayed pH-sensitive properties with controlled and sustained release. The dissolve-diffuse-erosion-degradation release process was described according to the dynamic models of drug release for SCD micelles. The results can be used as reference information for further studies in the biotechnology and pharmaceutical domains.

HIF-2α-targeted interventional chemoembolization multifunctional microspheres for effective elimination of hepatocellular carcinoma

Transcatheter arterial chemoembolization (TACE) is widely used for the treatment of advanced hepatocellular carcinoma (HCC). However, the long-term hypoxic microenvironment caused by TACE seriously affects the therapeutic effect of TACE. HIF-2α plays a crucial role on the chronic hypoxia process, which might be an ideal target for TACE therapy. Herein, a multifunctional polyvinyl alcohol (PVA)/hyaluronic acid (HA)-based microsphere (PT/DOX-MS) co-loaded with doxorubicin (DOX) and PT-2385, an effective HIF-2α inhibitor, was developed for enhanced TACE treatment efficacy. In vitro and in vivo studies revealed that PT/DOX-MS had a superior ability to treat HCC by blocking the tumor cells in G2/M phase, prompting cell apoptosis, and inhibiting tumor angiogenesis. The antitumor mechanisms of PT/DOX-MS were possibly due to that the introduction of PT-2385 could effectively inhibit the expression level of HIF-2α in hypoxic HCC cells, thereby down-regulating the expression levels of Cyclin D1, VEGF and TGF-α. In addition, the combination of DOX and PT-2385 could jointly inhibit VEGF expression, which was another reason accounting for the combined anti-cancer effect of PT/DOX-MS. Overall, our study demonstrated that PT/DOX-MS is a promising embolic agent for enhanced HCC treatment via the combined effect of hypoxia microenvironment improvement, chemotherapy, and embolization.

Recognition Sites for Cancer-targeting Drug Delivery Systems

BACKGROUND

Target-homing drug delivery systems are now gaining significant attention for use as novel therapeutic approaches in antitumor targeting for cancer therapy. Numerous targeted drug delivery systems have been designed to improve the targeting effects because these systems can display a range of favorable properties, thus, providing suitable characteristics for clinical applicability of anticancer drugs, such as increasing the solubility, and improving the drug distribution at target sites. The majority of these targeting systems are designed with respect to differences between cancerous and normal tissues, for instance, the low pH of tumor tissues or overexpressed receptors on tumor cell membranes. Due to the growing number of targeting possibilities, it is important to know the tumor-specific recognition strategies for designing novel, targeted, drug delivery systems. Herein, we identify and summarize literature pertaining to various recognition sites for optimizing the design of targeted drug delivery systems to augment current chemotherapeutic approaches.

OBJECTIVE

This review focuses on the identification of the recognition sites for developing targeted drug delivery systems for use in cancer therapeutics.

METHODS

We have reviewed and compiled cancer-specific recognition sites and their abnormal characteristics within tumor tissues (low pH, high glutathione, targetable receptors, etc.), tumor cells (receptor overexpression or tumor cell membrane changes) and tumor cell organelles (nuclear and endoplasmic reticular dysregulation) utilizing existing scientific literature. Moreover, we have highlighted the design of some targeted drug delivery systems that can be used as homing tools for these recognition sites.

RESULTS AND CONCLUSION

Targeted drug delivery systems are a promising therapeutic approach for tumor chemotherapy. Additional research focused on finding novel recognition sites, and subsequent development of targeting moieties for use with drug delivery systems will aid in the evaluation and clinical application of new and improved chemotherapeutics.

Phosphatidylserine targeting peptide-functionalized pH sensitive mixed micelles for enhanced anti-tumor drug delivery

In recent decades, targeted drug delivery systems (TDDS) have been widely used as an ideal method of improving therapeutic effects and reducing systemic side effects of chemotherapeutic agents. Historically, a handful of methods have been developed to further improve the targeting ability of delivery systems. Thus, in this study, two methods, taking advantage of tumor characteristics, were used for the creation of a multi-targeted delivery system. The first was the fabrication of pH-sensitive micelles, lending the ability to increase drug release by exploiting the acidic tumor environment. The second method was through utilization of the surface-exposed phosphatidylserine (PS) of tumors, which is normally found in the inner leaflet in healthy cells. Using PS as a target site, PS binding peptide (PSBP-6) was conjugated to pH-sensitive mixed micelles, (consisting of poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PDLLA) and poly (ethylene glycol)-b-poly (L-histidine) (PEG-PHIS)). After successful preparation of micelles, paclitaxel (PTX), a common chemotherapeutic agent, was selected to measure drug loading capacity and encapsulation efficiency, showing 7.9% and 83.5%, respectively. The in vitro release of PTX from mixed micelles at pH 5.0, 6.5, and 7.4 was 78.1, 56.8, and 51.4%, respectively, indicating acid-triggered drug release. The PSBP-6-modified, mixed micelles exhibited significantly enhanced in vitro cytotoxicity and demonstrated more efficient cellular uptake compared to unmodified mixed micelles in the HeLa cell line. Moreover, pharmacokinetic, in vivo biodistribution, and fluorescence imaging studies showed that PSBP-6-PEG-PDLLA/PEG-PHIS mixed micelles provide prolonged time in blood circulation and enhanced tumor accumulation. These results suggest that the use of PS as a novel targeting site is advantageous, and that these new multi-targeted mixed micelles show great potential for realization of broad prospects in the targeted treatment of tumors for chemotherapeutic delivery.