Notoginsenoside R1 counteracts mesenchymal stem cell-evoked oncogenesis and doxorubicin resistance in osteosarcoma cells by blocking IL-6 secretion-induced JAK2/STAT3 signaling.

Tumor microenvironment is a critical participant in the initiation, progression and drug resistance of carcinomas, including osteosarcoma. Notoginsenoside R1 (NGR1) is a proverbial active ingredient of the traditional Chinese medicine Panax notoginseng (PN) and possess undeniable roles in several cancers. Nevertheless, its function in osteosarcoma and tumor microenvironment remains elusive. In the current study, exposure to NGR1 dose-dependently inhibited osteosarcoma cell viability and migration, and induced apoptosis. Furthermore, osteosarcoma cells that were incubated with conditioned medium (CM) from bone marrow mesenchymal stem cells (BMSCs) exhibited greater proliferation, migration capacity and MMP-2 and MMP-9 expression relative to control cells, which was reversed when BMSCs were treated with NGR1. Notably, administration with NGR1 antagonized CM-evoked doxorubicin resistance in osteosarcoma cells by decreasing cell viability and increasing cell apoptosis and caspase-3/9 activity. Mechanically, NGR1 suppressed IL-6 secretion from BMSCs, as well as the subsequent activation of the JAK2/STAT3 signaling in osteosarcoma cells. In addition, blocking the JAK2 pathway by its antagonist AG490 reversed CM-induced osteosarcoma cell proliferation, migration and doxorubicin resistance. Moreover, exogenous supplementation with IL-6 engendered not only the reactivation of the JAK2/STAT3 signaling but also muted NGR1-mediated efficacy against osteosarcoma cell malignancy and doxorubicin resistance. Collectively, NGR1 may directly restrain osteosarcoma cell growth and migration, or indirectly antagonize MSC-evoked malignancy and drug resistance by interdicting IL-6 secretion-evoked activation of the JAK2/STAT3 pathway. Consequently, the current study may highlight a promising therapeutic strategy against osteosarcoma by regulating tumor cells and the tumor microenvironment.

Therapeutic impacts of GNE­477­loaded H2O2 stimulus­responsive dodecanoic acid­phenylborate ester­dextran polymeric micelles on osteosarcoma.

Osteosarcoma (OS) is a highly malignant primary bone neoplasm that is the leading cause of cancer­associated death in young people. GNE­477 belongs to the second generation of mTOR inhibitors and possesses promising potential in the treatment of OS but dose tolerance and drug toxicity limit its development and utilization. The present study aimed to prepare a novel H2O2 stimulus­responsive dodecanoic acid (DA)­phenylborate ester­dextran (DA­B­DEX) polymeric micelle delivery system for GNE­477 and evaluate its efficacy. The polymer micelles were characterized by morphology, size and critical micelle concentration. The GNE­477 loaded DA­B­DEX (GNE­477@DBD) tumor­targeting drug delivery system was established and the release of GNE­477 was measured. The cellular uptake of GNE­477@DBD by three OS cell lines (MG­63, U2OS and 143B cells) was analyzed utilizing a fluorescent tracer technique. The hydroxylated DA­B was successfully grafted onto dextran at a grafting rate of 3%, suitable for forming amphiphilic micelles. Following exposure to H2O2, the DA­B­DEX micelles ruptured and released the drug rapidly, leading to increased uptake of GNE­477@DBD by cells with sustained release of GNE­477. The in vitro experiments, including MTT assay, flow cytometry, western blotting and RT­qPCR, demonstrated that GNE­477@DBD inhibited tumor cell viability, arrested cell cycle in G1 phase, induced apoptosis and blocked the PI3K/Akt/mTOR cascade response. In vivo, through the observation of mice tumor growth and the results of H&E staining, the GNE­477@DBD group exhibited more positive therapeutic outcomes than the free drug group with almost no adverse effects on other organs. In conclusion, H2O2­responsive DA­B­DEX presents a promising delivery system for hydrophobic anti­tumor drugs for OS therapy.

Effects of soybean isoflavone on metabolism of rat osteoblasts and cytokines in vitro.

The effects and mechanisms of soybean isoflavone on osteoblast (OB) proliferation in vitro were investigated. Fifty female Wistar rats were randomly divided into five groups with 10 rats in each group. Rat OBs were separated and cultured. The first generation of OBs cultured for 48 hr at various concentrations of isoflavone were set as the experimental groups, the OBs exposed to estradiol (E2 ) culture were considered as positive control group. The biological characterization of OBs was investigated by phase contrast microscopy and alkaline phosphatase (ALP) histochemistry. The concentrations of interleukin (IL-1), osteoprotegerin (OPG), transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and vascular endothelial growth factor (VEGF) in isoflavone culture solutions were determined. Proliferation rate of OBs was increased in experimental group comparing that in the blank group. ALP activity in experimental group was higher than that in blank group. No significant differences of ALP activity were observed between E2 culture group and isoflavone group at concentrations of 10-5 and 10-7 mM (P > 0.05). Furthermore, in the experimental groups at low isoflavone concentrations, the concentrations of OPG, TGF, and VEGF were increased and positively correlated with OB proliferation. However, the concentrations of IL-1, GM-CSF were decreased at higher concentration of isoflavone and were negatively correlated with OB proliferation. Soybean isoflavone could promote the growth and proliferation of rat OB, it might act as the stimulator of OPG, TGF, and VEGF pathway, and the inhibitor of IL-1, GM-CSF pathway as well.