Metastatic and recurrent bone primary bone cancers

Effect of the Notch1-mediated PI3K-Akt-mTOR pathway in human osteosarcoma

Purpose: Osteosarcoma is one of the most common malignant bone tumours in early adolescence. The incidence rate of osteosarcoma has stagnated over the past 30 years, highlighting the need to develop novel therapies. In osteosarcoma cells, Notch1 expression is absent, and the Notch1 pathway is related to cancer cell proliferation, apoptosis and autophagy. Our study aimed to investigate the role of Notch1 in osteosarcoma development.

Methods: We measured NICD1 expression induced by doxycycline treatment at various concentrations. The viability of human osteosarcoma cells (MG-63) induced by doxycycline was measured. Flow cytometry and cell apoptosis analysis were conducted to measure the effect of Notch1 on the cell cycle of human osteosarcoma cells. We also used a GFP-LC3 plasmid to detect Notch1-induced autophagy in MG-63 cells. Western blotting was conducted to analyse expression of the PI3K/Akt/mTOR signalling pathway through Notch1 induction by doxycycline.

Results: In this study, we demonstrated that Notch1 activation by doxycycline potently suppressed cell proliferation by inducing S phase arrest in osteosarcoma cells. Doxycycline-induced Notch1 activation also induced apoptosis and autophagy in osteosarcoma cells. Moreover, we found that Notch1 inhibited PI3K/Akt/mTOR signalling to induce apoptosis and autophagy.

Conclusion: In summary, our results revealed that Notch1 activation by doxycycline induces S phase arrest, apoptosis and autophagy by blocking PI3K/Akt/mTOR signalling in human osteosarcoma cells. Notch1 may be a potential clinical antitumour target for osteosarcoma therapy.

Docetaxel, bevacizumab, and gemcitabine for very high risk sarcomas in adolescents and young adults: A single-center experience

BACKGROUND

Adolescent and young adult (AYA) patients with very high risk sarcomas have poor outcomes and are in need of novel therapies.

PROCEDURE

From January 2005 to February 2016, we retrospectively identified all AYA patients with relapsed or metastatic high-grade sarcomas, who were treated with at least one cycle of docetaxel (T), bevacizumab (A), and gemcitabine (G) (TAG ; T = 100 mg/m² Day 8, A = 15 mg/kg Day 1, G = 1,000 mg/m² Days 1 and 8).

RESULTS

Fourteen patients, median age of 20 (15-30), received a total of 80 cycles of TAG, and were followed for a median of 83 months. Diagnosis included osteosarcoma (OST; 8), Ewing sarcoma (3), and soft tissue sarcoma (3). Five of 14 patients achieved clinical remission (CR), 3 had partial responses (PR), 3 had stable disease (SD), and 3 had progressive disease (PD). The median progression-free survival and overall survival were 7 and 19 months, respectively. The objective response rate (CR + PR) and tumor control rate (CR + PR + SD) were 57% and 79%, respectively, with two patients alive after 5 years; toxicities included thrombocytopenia, neutropenia, and capillary leak syndrome.

CONCLUSIONS

Our study builds on previous studies utilizing TAG in adult leiomyosarcoma (LMS) by focusing on AYA, non-LMS sarcomas, especially OST. Our experience suggests that TAG is well tolerated and has activity in very high risk sarcomas in AYA.

Aloe-emodin-mediated photodynamic therapy induces autophagy and apoptosis in human osteosarcoma cell line MG‑63 through the ROS/JNK signaling pathway

The present study was carried out to investigate the effect and mechanisms of aloe-emodin (AE)-mediated photodynamic therapy (AE-PDT) on the human osteosarcoma cell line MG-63. After treatment with AE-PDT, the human osteosarcoma cell line MG-63 was tested for levels of viability, autophagy, reactive oxygen species (ROS) and apoptosis and changes in cell morphology with the Cell Counting Kit-8 (CCK-8), monodansylcadaverine (MDC) and Hoechst staining and transmission electron microscopy. The expression of proteins including LC-3, cleaved caspase-3, Beclin-1, Bcl-2, p-JNK, t-JNK and β-actin was examined with western blotting. AE-PDT significantly inhibited the viability of the MG-63 cells in an AE-concentration- and PDT energy density-dependent manner. Autophagy and apoptosis of MG-63 cells was substantially promoted in the AE-PDT group compared to the control group, the AE alone group and the light emitting diode (LED) alone group. Inhibition of autophagy by 3-meth-yladenine (3-MA) (5 mM) and chloroquine (CQ) (15 µM) significantly promoted the apoptosis rate and improved the sensitivity of the MG-63 cells to AE-PDT. AE-PDT was found to induce the expression of ROS and p-JNK. ROS scavenger, N-acetyl-L-cysteine (NAC, 5 mM), was able to hinder the autophagy, apoptosis and phosphorylation of JNK, and JNK inhibitor (SP600125, 10 µM) significantly inhibited the autophagy and apoptosis, and attenuated the sensitivity of MG63 cells to AE-PDT. In conclusion, AE-PDT induced the autophagy and apoptosis of human osteosarcoma cell line MG-63 through the activation of the ROS-JNK signaling pathway. Autophagy may play a protective role during the early stage following treatment of AE-PDT.