Betulin inhibits mTOR and induces autophagy to promote apoptosis in human osteosarcoma cell lines.

Betulin is a lupane type pentacyclic triterpenoid, and commonly found in the bark of birch trees. It displays various pharmacological properties, such as antibacterial, anti-inflammation, antitumor, and antiviral. In this report, we attempted to investigate the anti-proliferative and pro-apoptotic effects of betulin on osteosarcoma cell lines. Our results revealed that betulin significantly decreased cell viability and colony formation in osteosarcoma cell lines. Dose-dependent induction of Annexin V positive cells, activated caspase 8, activated caspase 9, activated caspase 3, and the cleavage of poly (ADP-ribose) polymerase were observed after the treatment with betulin, indicating betulin induces apoptosis in osteosarcoma cell lines. mTOR has been identified as a key modulator of autophagy in response to different stresses. In this study, we found that the treatment with betulin suppressed the activation of mTOR, and increased the level of LC 3-II, the autophagy marker, in osteosarcoma cell lines. Co-administration of the autophagy inhibitor chloroquine significantly rescued the cell viability and the clonogenic activity in betulin-treated osteosarcoma cell lines. Our data showed that betulin induced autophagy, and the up-regulated autophagy positively contributed to the apoptosis. Taken together, our findings suggested that betulin may serve as a promising anti-proliferative agent for treating osteosarcoma.

Carnosol-Induced ROS Inhibits Cell Viability of Human Osteosarcoma by Apoptosis and Autophagy.

Carnosol is an anti-oxidant and anti-inflammatory compound from rosemary. In this paper, we investigated antitumor activity of carnosol against human osteosarcoma cells. We found the viability of human osteosarcoma MG-63 cells was significantly decreased in the presence of carnosol (cell viabilities: 17.2% for 20[Formula: see text]µg/ml of CS vs. 100% for control, [Formula: see text]). Carnosol induced apoptosis and cell cycle arrest in a dose-dependent manner in MG-63 cells. Furthermore, carnosol exposure increased the levels of reactive oxygen species (ROS). The pre-treatment of NAC, the ROS scavenger, blocked the inhibition of cell viability in the carnosol treatment, indicating that ROS is important in the antiproliferation effect. Moreover, we demonstrated that carnosol significantly induced autophagy and co-administration of autophagy inhibitor reduced the antiproliferating effect of carnosol. This result exhibited the cytotoxic effect of autophagy induced by carnosol in MG-63 cells. Interestingly, the treatment of NAC decreased carnosol-induced autophagy. Collectively, these data indicate that carnosol suppresses the viability of human osteosarcoma MG-63 cells by upregulation of apoptosis and autophagy, which are both mediated by ROS. Thus, carnosol might serve as a potential therapeutic agent against osteosarcoma.

Continuous Wave Spectroscopy with Diffusion Theory for Quantification of Optical Properties: Comparison Between Multi-distance and Multi-wavelength Data Fitting Methods.

Typically, continuous wave spectroscopy (CWS) can be used to accurately quantify biological tissue optical properties (µ a and µ s ') by employing the diffuse reflectance information acquired at multiple source-detector separations (multi-distance). On the other hand, sample optical properties can also be obtained by fitting multi-wavelength light reflectance acquired at a single source detector separation to the diffusion theory equation. To date, multi-wavelength and multi-distance methods have not yet been rigorously compared for their accuracy in quantification of the sample optical properties. In this investigation, we compared the accuracy of the two above-mentioned quantifying methods in the optical properties recovery. The liquid phantoms had µ a between 0.004 and 0.011 mm(-1) and µ s ' between 0.55 and 1.07 mm(-1) whose optical properties mimic the human breast. Multi-distance data and multi-wavelength data were fitted to the same diffusion equation for consistency. The difference between benchmark µ a and µ s ' and the fitted results, ΔError (ΔE) was used to evaluate the accuracy of the two methods. The results showed that either method yielded ΔE within 15-30 % when values were within certain limits to standard values applicable to µ s ' and µ a for human adipose tissue. Both methods showed no significant differences in ΔE values. Our results suggest that both multi-distance and multi-wavelength methods can yield similar reasonable optical properties in biological tissue with a proper calibration.