Inorganic Kernel-Reconstituted Lipoprotein Biomimetic Nanovehicles Enable Efficient Targeting "Trojan Horse" Delivery of STAT3-Decoy Oligonucleotide for Overcoming TRAIL Resistance

Recent Development of LDL-Based Nanoparticles for Cancer Therapy

Low-density lipoprotein (LDL), a natural lipoprotein transporting cholesterol in the circulatory system, has been a possible drug carrier for targeted delivery. LDL can bind to the LDL receptor (LDLR) with its outside apolipoprotein B-100 and then enter the cell via LDLR-mediated endocytosis. This targeting function inspires researchers to modify LDL to deliver different therapeutic drugs. Drugs can be loaded in the surficial phospholipids, hydrophobic core, or apolipoprotein for the structure of LDL. In addition, LDL-like synthetic nanoparticles carrying therapeutic drugs are also under investigation for the scarcity of natural LDL. In addition to being a carrier, LDL can also be a targeting molecule, decorated to the surface of synthetic nanoparticles loaded with cytotoxic compounds. This review summarizes the properties of LDL and the different kinds of LDL-based delivery nanoparticles, their loading strategies, and the achievements of the recent anti-tumor advancement.

Nanoparticle-Mediated Delivery of STAT3 Inhibitors in the Treatment of Lung Cancer

Lung cancer is a common malignancy worldwide, with high morbidity and mortality. Signal transducer and activator of transcription 3 (STAT3) is an important transcription factor that not only regulates different hallmarks of cancer, such as tumorigenesis, cell proliferation, and metastasis but also regulates the occurrence and maintenance of cancer stem cells (CSCs). Abnormal STAT3 activity has been found in a variety of cancers, including lung cancer, and its phosphorylation level is associated with a poor prognosis of lung cancer. Therefore, the STAT3 pathway may represent a promising therapeutic target for the treatment of lung cancer. To date, various types of STAT3 inhibitors, including natural compounds, small molecules, and gene-based therapies, have been developed through direct and indirect strategies, although most of them are still in the preclinical or early clinical stages. One of the main obstacles to the development of STAT3 inhibitors is the lack of an effective targeted delivery system to improve their bioavailability and tumor targetability, failing to fully demonstrate their anti-tumor effects. In this review, we will summarize the recent advances in STAT3 targeting strategies, as well as the applications of nanoparticle-mediated targeted delivery of STAT3 inhibitors in the treatment of lung cancer.

STAT3 pathway in cancers: Past, present, and future

Signal transducer and activator of transcription 3 (STAT3), a member of the STAT family, discovered in the cytoplasm of almost all types of mammalian cells, plays a significant role in biological functions. The duration of STAT3 activation in normal tissues is a transient event and is strictly regulated. However, in cancer tissues, STAT3 is activated in an aberrant manner and is induced by certain cytokines. The continuous activation of STAT3 regulates the expression of downstream proteins associated with the formation, progression, and metastasis of cancers. Thus, elucidating the mechanisms of STAT3 regulation and designing inhibitors targeting the STAT3 pathway are considered promising strategies for cancer treatment. This review aims to introduce the history, research advances, and prospects concerning the STAT3 pathway in cancer. We review the mechanisms of STAT3 pathway regulation and the consequent cancer hallmarks associated with tumor biology that are induced by the STAT3 pathway. Moreover, we summarize the emerging development of inhibitors that target the STAT3 pathway and novel drug delivery systems for delivering these inhibitors. The barriers against targeting the STAT3 pathway, the focus of future research on promising targets in the STAT3 pathway, and our perspective on the overall utility of STAT3 pathway inhibitors in cancer treatment are also discussed.

Gather wisdom to overcome barriers: Well-designed nano-drug delivery systems for treating gliomas

Due to the special physiological and pathological characteristics of gliomas, most therapeutic drugs are prevented from entering the brain. To improve the poor prognosis of existing therapies, researchers have been continuously developing non-invasive methods to overcome barriers to gliomas therapy. Although these strategies can be used clinically to overcome the blood‒brain barrier (BBB), the accurate delivery of drugs to the glioma lesions cannot be ensured. Nano-drug delivery systems (NDDS) have been widely used for precise drug delivery. In recent years, researchers have gathered their wisdom to overcome barriers, so many well-designed NDDS have performed prominently in preclinical studies. These meticulous designs mainly include cascade passing through BBB and targeting to glioma lesions, drug release in response to the glioma microenvironment, biomimetic delivery systems based on endogenous cells/extracellular vesicles/protein, and carriers created according to the active ingredients of traditional Chinese medicines. We reviewed these well-designed NDDS in detail. Furthermore, we discussed the current ongoing and completed clinical trials of NDDS for gliomas therapy, and analyzed the challenges and trends faced by clinical translation of these well-designed NDDS.

Crosstalk of low density lipoprotein and liposome as a paradigm for targeting of 5-fluorouracil into hepatic cells: cytotoxicity and liver deposition

This study aimed to utilize cholesterol conjugation of 5-fluorouracil (5-FUC) and liposomal formulas to enhance the partitioning of 5-FU into low density lipoprotein (LDL) to target hepatocellular carcinoma (HCC). Thus, 5-FU and 5-FUCwere loaded into liposomes. Later, the direct loading and transfer of 5-FU, and 5-FUC from liposomes into LDL were attained. The preparations were characterized in terms of particle size, zeta potential, morphology, entrapment efficiency, and cytotoxicity using the HepG2 cell line. Moreover, the drug deposition into the LDL and liver tissues was investigated. The present results revealed that liposomal preparations have a nanosize range (155 - 194 nm), negative zeta potential (- 0.82 to - 16 mV), entrapment efficiency of 69% for 5-FU, and 66% for 5-FUC. Moreover, LDL particles have a nanosize range (28-49 nm), negative zeta potential (- 17 to -27 mV), and the entrapment efficiency is 11% for 5-FU and 85% for 5-FUC. Furthermore, 5-FUC loaded liposomes displayed a sustained release profile (57%) at 24 h compared to fast release (92%) of 5-FU loaded liposomes. 5-FUC and liposomal formulas enhanced the transfer of 5-FUC into LDL compared to 5-FU. 5-FUC loaded liposomes and LDL have greater cytotoxicity against HepG2 cell lines compared to 5-FU and 5-FUC solutions. Moreover, the deposition of 5-FUC in LDL (26.87ng/mg) and liver tissues (534 ng/gm tissue) was significantly increased 5-FUC liposomes compared to 5-FU (11.7 ng/g tissue) liposomal formulation. In conclusion, 5-FUC is a promising strategy for hepatic targeting of 5-FU through LDL-mediated gateway.

Design and encapsulation of anticancer dual HSP27 and HER2 inhibitor into low density lipoprotein to target ovarian cancer cells

Tumor cells overexpress low-density lipoprotein (LDL) receptors (LDL-r). Hence, LDL is proposed as a targeting shuttle of anticancer drugs. Therefore, the objective of this study was to synthesize a dual inhibitor of heat shock protein 27 (HSP27) and human epidermal growth factor receptor 2 (HER2) conjugated with cholesterol and encapsulated into LDL for selective targeting of ovarian cancer cells. In the present study, the anticancer agent and its cholesterol conjugate were successfully prepared and characterized physically for color, shape, and melting point. Moreover, the compounds were chemically characterized for ¹H NMR and ¹³C NMR spectra using FTIR and LCMS/MS. Our results revealed that the prepared anticancer agent and its cholesterol conjugate elicited dual HSP27 and HER2 inhibition, as confirmed using western blotting. The anticancer agent (compound D) entered cells and targeted the HSP27 function, thereby reducing HER2 expression. However, a cholesterol-conjugated anticancer agent (compound F) had high cellular uptake and inhibited the growth of SKOV3 cells after encapsulation into LDL. The obtained results concluded that the design of an LDL-encapsulated cholesterol-conjugated HSP27-HER2 dual inhibitor may be a promising approach to realize specific targeted achieve killing of ovarian cancer.

RUNX3 enhances TRAIL-induced apoptosis by upregulating DR5 in colorectal cancer

RUNX3 is frequently inactivated by DNA hypermethylation in numerous cancers. Here, we show that RUNX3 has an important role in modulating apoptosis in immediate response to tumor necrosis factor-related apoptosis-including ligand (TRAIL). Importantly, no combined effect of TRAIL and RUNX3 was observed in non-cancerous cells. We investigated the expression of the death receptors (DRs) DR4 and DR5, which are related to TRAIL resistance. Overexpression of RUNX3 increased DR5 expression via induction of the reactive oxygen species (ROS)-endoplasmic reticulum (ER) stress-effector CHOP. Reduction of DR5 markedly decreased apoptosis enhanced by the combined therapy of TRAIL and RUNX3. Interestingly, RUNX3 induced reactive oxygen species production by inhibiting SOD3 transcription via binding to the Superoxide dismutase 3 (SOD3) promoter. Additionally, the combined effect of TRAIL and RUNX3 decreased tumor growth in xenograft models. Our results demonstrate a direct role for RUNX3 in TRAIL-induced apoptosis via activation of DR5 and provide further support for RUNX3 as an anti-tumor.

Effect of STAT3 decoy oligodeoxynucleotides mediated by ultrasound-targeted microbubbles combined with ultrasound on the growth of squamous cell carcinoma of the esophagus

Effect of STAT3 decoy oligodeoxynucleotides (ODN) transduced by ultrasound microbubbles combined with ultrasound on the growth of esophageal squamous cell carcinoma and its mechanism were analyzed. EC9706 cells were cultured in vitro and divided into four groups: group E (ultrasound microbubble + ultrasound irradiation), group P (liposome + ultrasound irradiation), group C (ultrasound), and group CC (ultrasound microbubbles). Mutant ODNs were used in groups E and P and the control group was group EC and PC, respectively. Immunofluorescence assay and flow cytometry were used to detect the transfection efficiency of each group. MTT colorimetric assay was performed to analyze the inhibition rate in each group. The effect of STAT3 decoy ODN on the proliferation of esophageal squamous carcinoma cells was calculated. Revese transcription-quantitative PCR (RT-qPCR) and western blotting were performed to detect the expression of the STAT signaling pathway downstream of gene expression levels. The model of subcutaneous transplantation of nude mice was used to show the effect of different transfections and STAT3 decoy ODN on the weight and volume of the transplanted tumor in mice. The cell inhibition rate was higher in group E than in groups P (F=8.382, P<0.001) and CC (F=6.469, P<0.001). Compared with groups EC, PC and C, respectively, the mRNA expression of STAT3, bcl-xL and Cyclin D1 decreased in groups E, P and CC (F=5.328, P<0.001). The weight and volume of nude mice in groups E, P and CC exhibited an inhibitory effect on the weight and volume of nude mice. Ultrasound irradiation combined with ultrasound microbubbles is an effective transfection method. The transfection of STAT3 decoy ODN can significantly inhibit the activity of esophageal squamous cell carcinoma cells and enhance apoptosis of cells, which has potential clinical value.