Liposomal Doxorubicin: the Sphingomyelin/Cholesterol System Significantly Enhances the Antitumor Efficacy of Doxorubicin.

Doxorubicin (DOX) has a cytotoxic effect on many tumor cells; however, its clinical application is limited owing to its strong side effects. Although Doxil® reduces the cardiotoxicity of free DOX, it has also introduced a new dose-limiting toxicity. In a previous study, a sialic acid-cholesterol conjugate (SA-CH) was synthesized and modified onto the surface of DOX-loaded liposomes to target tumor-associated macrophages (TAMs), further improving the efficacy of DOX-loaded liposomes over that of Doxil®. Meanwhile, the good retention characteristics and promising antitumor ability of sphingomyelin/cholesterol (SM/CH) system for water-soluble drugs have attracted wide attention. Therefore, we aimed to use SA-CH as the target and hydrogenated soybean phosphatidylcholine (HSPC) or egg sphingomyelin (ESM) as the membrane material to develop a more stable DOX-loaded liposome with stronger antitumor activity. The liposomes were evaluated for particle size, polydispersity index, zeta potential, entrapment efficiency, in vitro release, long-term storage, cytotoxicity, cellular uptake, pharmacokinetics, tumor targetability, and in vivo antitumor activity. In the liposomes prepared using HSPC/CH, sialic acid (SA) modification considerably increased the accumulation of DOX-loaded liposomes in the tumor, thus exerting a better antitumor effect. However, SA modification in DOX-ESL (SA-CH-modified DOX-loaded liposomes prepared by ESM/CH) destroyed the strong retention effect of the ESM/CH system on DOX, resulting in a reduced antitumor effect. Notably, DOX-ECL (DOX-loaded liposome prepared by ESM/CH) had the optimal storage stability, lowest toxicity, and optimal antitumor effect due to better drug retention properties. Thus, the ESM/CH liposome of DOX is a potential drug delivery system. Sketch of the effect of two DOX-loaded liposomes with hydrogenated soybean phospholipid (HSPC) and egg sphingomyelin (ESM) as lipid membrane material and surface-modified SA derivative on tumor growth inhibition.

An Application of Tumor-Associated Macrophages as Immunotherapy Targets: Sialic Acid-Modified EPI-Loaded Liposomes Inhibit Breast Cancer Metastasis.

Breast cancer metastasis is an important cause of death in patients with breast cancer and is closely related to circulating tumor cells (CTCs) and the metastatic microenvironment. As the most infiltrating immune cells in the tumor microenvironment (TME), tumor-associated macrophages (TAMs), which highly express sialic acid (SA) receptor (Siglec-1), are closely linked to tumor progression and metastasis. Furthermore, the surface of CTCs also highly expressed receptor (Selectin) for SA. A targeting ligand (SA-CH), composed of SA and cholesterol, was synthesized and modified on the surface of epirubicin (EPI)-loaded liposomes (EPI-SL) as an effective targeting delivery system. Liposomes were evaluated for characteristics, stability, in vitro release, cytotoxicity, cellular uptake, pharmacokinetics, tumor targeting, and pharmacodynamics. In vivo and in vitro experiments showed that EPI-SL enhanced EPI uptake by TAMs. In addition, cellular experiments showed that EPI-SL could also enhance the uptake of EPI by 4T1 cells, resulting in cytotoxicity second only to that of EPI solution. Pharmacodynamic experiments have shown that EPI-SL has optimal tumor inhibition with minimal toxicity, which can be ascribed to the fact that EPI-SL can deliver drugs to tumor based on TAMs and regulate TME through the depletion of TAMs. Our study demonstrated the significant potential of SA-modified liposomes in antitumor metastasis. Schematic diagram of the role of SA-CH modified EPI-loaded liposomes in the model of breast cancer metastasis.

Deuterated colchicine liposomes based on oligomeric hyaluronic acid modification enhance anti-tumor effect and reduce systemic toxicity.

Deuterated drugs are produced by substituting hydrogen atoms with deuterium atoms at specific sites in a drug molecule to prolong its metabolic cycle and reduce the production of toxic metabolites. Deuterated drugs have recently attracted increasing attention from the pharmaceutical industry. Colchicine exhibits a strong anti-tumor activity but has a short half-life, rapid attenuated drug concentration, narrow treatment window, and lack of tumor-specific targeting in vivo, resulting in toxicity and side effects. In this study, we explored whether deuteration could reduce the toxicity of colchicine. We prepared deuterated colchicine liposomes coated with oligo-hyaluronic acid, which can bind to the tumor-specific CD44 receptor and reduce the clearance of immune cells from the blood, resulting in a long blood circulation time and active targeting. We observed that deuteration of the colchicine B ring reduced drug toxicity and improved the anti-tumor response in 4 T1 breast cancer. Liposomes modified with oligo-hyaluronic acid exhibited increased tumor accumulation, further improving the anti-tumor effect of the drugs. Our results provide a basis for the development and application of deuterated drugs in the field of nano-preparations.

MicroRNA-34a and microRNA-146a target CELF3 and suppress the osteogenic differentiation of periodontal ligament stem cells under cyclic mechanical stretch.

Background/purpose: During orthodontic tooth movement, mechanical forces induce the osteogenic differentiation of periodontal ligament stem cells (PDLSCs), which contributes to alveolar bone remodeling. MicroRNAs (miRNAs) are involved in regulating PDLSC osteogenic differentiation. Therefore, we intended to explore the role of miR-34a and miR-146a in osteogenic differentiation of PDLSCs under cyclic stretch. Materials and methods: Phenotypic identification of PDLSCs was determined by flow cytometry analysis. PDLSCs were incubated with osteogenic differentiation medium for 3 weeks and the osteogenic differentiation capability was detected by Alizarin Red staining. To mimic the orthodontic forces, cyclic mechanical stretch was applied to PDLSCs. Alkaline phosphatase (ALP) activity assay and ALP staining were used for evaluating the ALP activity. The expression of osteogenesis markers in PDLSCs was assessed by western blotting and qRT-PCR. The binding between miR-34a (or miR-146a) and CUGBP Elav-like family member 3 (CELF3) was validated by luciferase reporter assay. Results: Cyclic stretch elevated ALP activity and the expression of osteogenesis markers, osteopontin (OPN), runt-related transcription factor 2 (RUNX2), type I collagen (COL1), ALP, osteocalcin (OCN) and osterix (OSX), in PDLSCs. MiR-146a and miR-34a were downregulated in PDLSCs under cyclic stretch. Either overexpressing miR-146a and miR-34a reduced ALP activity and the expression of osteogenesis markers. CELF3 was a target of both miR-146a and miR-34a. CELF3 silencing attenuated while CELF3 overexpression enhanced ALP activity and the expression of osteogenesis markers. Conclusion: MiR-34a and miR-146a repress cyclic stretch-induced osteogenic differentiation of PDLSCs via regulating the expression of CELF3.