Burmannic Acid Inhibits Proliferation and Induces Oxidative Stress Response of Oral Cancer Cells

Abstract

Burmannic acid (BURA) is a new apocarotenoid bioactive compound derived from Indonesian cinnamon; however, its anticancer effect has rarely been investigated in oral cancer cells. In this investigation, the consequences of the antiproliferation of oral cancer cells effected by BURA were evaluated. BURA selectively suppressed cell proliferation of oral cancer cells (Ca9-22 and CAL 27) but showed little cytotoxicity to normal oral cells (HGF-1). In terms of mechanism, BURA perturbed cell cycle distribution, upregulated mitochondrial superoxide, induced mitochondrial depolarization, triggered γH2AX and 8-hydroxy-2-deoxyguanosine DNA damage, and induced apoptosis and caspase 3/8/9 activation in oral cancer cells. Application of N-acetylcysteine confirmed oxidative stress as the critical factor in promoting antiproliferation, apoptosis, and DNA damage in oral cancer cells.

Antiproliferation- and Apoptosis-Inducible Effects of a Novel Nitrated [6,6,6]Tricycle Derivative (SK2) on Oral Cancer Cells

“…A pancaspase-FITC kit (Abcam, Cambridge, UK) enables a general detection of caspase-signaling activators such as caspase-1 and 3 to 9 [ 19 ]. Moreover, the individual activity of Cas 3, Cas 8, and Cas 9 was detected using OncoImmunin kits (Gaithersburg, MD, USA) [ 54 , 55 ]. Cells were treated with 10 μM substrate (PhiPhiLux-G1D2, CaspaLux8-L1D2, and CaspaLux9-M1D2) (1:1000) at 37 °C for 1 h. These substrates were individually cleaved by activated Cas 3, Cas 8, and Cas 9 to generate green fluorescence.…”

“…The MitoSOX was probed using MitoSOX™ Red (Molecular Probes, Invitrogen, Eugene, OR, USA), producing fluorescence for flow cytometry [ 55 ]. In brief, cells were treated with 5 μM MitoSOX at 37 °C for 30 min.…”

“…The MMP was probed using MitoProbe™ DiOC 2 (3) (Invitrogen, San Diego, CA, USA), producing fluorescence for flow cytometry [ 55 ]. Cells were treated with 20 nM DiOC 2 (3) for 30 min.…”

“…Utilizing flow cytometry, the γH2AX level was detected using a p-Histone H2A.X (Ser 139) antibody (Santa Cruz Biotechnology, Santa Cruz, CA, USA) (1:50 dilution) at 4 °C for 1 h [ 55 ]. Subsequently, an Alexa Fluor 488-conjugated secondary antibody (Jackson Laboratory, Bar Harbor, ME, USA) (1:50 dilution) was used for 30 min at RT.…”

“…Utilizing flow cytometry, 8-OHdG, an oxidative nucleotide marker, was assessed using an 8-OHdG-FITC antibody (Santa Cruz Biotechnology) at a 100X dilution for 1 h at RT [ 55 ]. Finally, flow cytometry analysis was performed using an Accuri C6 using the FL1 channel.…”