Delivery of RGD-modified liposome as a targeted colorectal carcinoma therapy and its autophagy mechanism

Liposomes are among the most extensively applied drug carriers due to their excellent biocompatibility, controllable size and ease of modification. In the present study, we prepared untargeted liposomes (LP) and targeting liposomes modified with Arg-Gly-Asp (RGD-LP), and Doxorubicin Hydrochloride (DOX) or fluorescent probe was loaded. RGD-LP/DOX was identified to be uniformly spherical in size 131.2 ± 2.7 nm. Based on flow cytometry analysis and the confocal laser scanning microscopy, RGD-LP had a higher uptake into HRT-18 colorectal cancer cells than LP. Further, in vivo imaging study further suggested that RGD-LP could significantly increase the liposome accumulation in the tumour tissues of the mice bearing subcutaneous tumours. By investigating the targeting mechanism of RGD-LP, we found that they entered the cell via macropinocytosis. When loaded with DOX, RGD-LP exerted stronger tumour growth inhibitory activity against tumours of colorectal carcinoma compared to LP. Moreover, RGD-LP induced autophagy. Therefore, RGD-LP have the potential to be applied as a targeted colorectal carcinoma therapy.

The functions of exosomes targeting astrocytes and astrocyte-derived exosomes targeting other cell types

Astrocytes are the most abundant glial cells in the central nervous system; they participate in crucial biological processes, maintain brain structure, and regulate nervous system function. Exosomes are cell-derived extracellular vesicles containing various bioactive molecules including proteins, peptides, nucleotides, and lipids secreted from their cellular sources. Increasing evidence shows that exosomes participate in a communication network in the nervous system, in which astrocyte-derived exosomes play important roles. In this review, we have summarized the effects of exosomes targeting astrocytes and the astrocyte-derived exosomes targeting other cell types in the central nervous system. We also discuss the potential research directions of the exosome-based communication network in the nervous system. The exosome-based intercellular communication focused on astrocytes is of great significance to the biological and/or pathological processes in different conditions in the brain. New strategies may be developed for the diagnosis and treatment of neurological disorders by focusing on astrocytes as the central cells and utilizing exosomes as communication mediators.

Navigations of the targeting pathway of nanomedicines towards tumor

INTRODUCTION

Nanomedicines (NMs) have emerged as a promising approach for revolutionizing cancer treatment outcomes, mainly due to their benefits in the tumor targeted delivery of therapeutics. The preferential accumulation of NMs in tumor has been widely verified by macroscopical technologies. Accordingly, several classic and emerging targeting mechanisms have been proposed to support the tumor-specific delivery of NMs. The targeting mechanism has been a topic of intensive interest and controversy in the field of NMs development. Especially, the mechanisms by which NMs target tumor remain elusive.

AREA COVERED

This topical review mainly discussed the evolution of the targeting mechanisms, crucial issues associated with each mechanism, and confused debates among the mechanisms. The targeting mechanisms of tumor-specific NMs discussed here include the enhanced permeability and retention (EPR) effect, protein corona-mediated targeting delivery, circulating cell mediated transportation, and transcytosis.

EXPERT OPINION

It is of great significance for ultimate clinical translation to have more comprehensive considerations on the mechanism driving the pathway of NMs toward tumors. Our thoughts in this review are expected to provide comprehensive understanding on the mechanisms and elicit thorough explorations on new mechanism to renovate the knowledge framework of NMs delivery.

Triple-controlled oncolytic adenovirus expressing melittin to exert inhibitory efficacy on hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant disease, and its outcome of routine therapies is poor. Comprehensive treatment including gene therapy is an important way to improve patients' prognosis and survival. In this study, we successfully constructed a triple-controlled cancer-selective oncolytic adenovirus, QG511-HA-Melittin, carrying melittin gene, in which the hybrid promoter, hypoxia-response element (HRE)-AFP promoter, was used to control viral E1a expression targeting AFP-positive cancer cells in hypoxia microenviroment, and the E1b-55 kDa gene was deleted in cancer cells with p53-deficiency. The cytological experiments found that the viral replication of QG511-HA-Melittin was increased to 12800-folds in Hep3B cells within 48 h, and 130-folds in SMMC-7721, but the virus did not replicate in L-02 cells. QG511-HA-Melittin had a strong inhibition effect on AFP-positive HCC cell proliferation, such as Hep3B and HepG2, whereas, there was low or no inhibition effect of QG511-HA-Melittin on AFP-negative cancer cells SMMC-7721 and normal cells L-02. In the in vivo experiment, compared with the blank control group, QG511-HA-Melittin can significantly inhibit the growth of HCC xenografts (P<0.05). The survival of mice in QG511-HA-Melittin group was much longer than that of the blank control group. Both in vitro and in vivo experiments manifested that QG511-HA-Melittin exerts an inhibitory effect on HCC cells, which may provide a new strategy for HCC biotherapy.