ABSTRACT
Honokiol (HNK) is a small organic molecule purified from magnolia species and has demonstrated anticancer activities in a variety of cancer cell lines; however, its effect on oral squamous cell carcinoma (OSCC) cells is unknown. We investigated the antitumor activities of HNK on OSCC cells in vitro for the first time. The inhibitory effects of HNK on the growth and proliferation of OSCC cells were demonstrated via in vitro 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and propidium iodide (PI) assays, and the apoptotic cells were investigated by the observation of morphological changes and detection of DNA fragmentation via PI, TdT-mediated dUTP-biotin nick end labeling (TUNEL), and DNA ladder assays, as well as flow cytometry assay. The results showed that HNK inhibited the growth and proliferation of OSCC cells in vitro in a time and dose-dependent manner. The inhibitory effect was associated with the cell apoptosis induced by HNK, evidenced by the morphological features of apoptotic cells, TUNEL-positive cells and a degradation of chromosomal DNA into small internucleosomal fragments. The study also demonstrated here that the inhibition or apoptosis mediated by 15 microg x mL(-1) or 20 microg x mL(-1) of HNK were more stronger compared with those of 20 microg x mL(-1) 5-fluorouracil (5-Fu, the control) applied to OSCC cells, when the ratio of OSCC cell numbers were measured between the treatment of different concentrations of HNK to the 5-Fu treatment for 48 h. HNK is a promising compound that can be potentially used as a novel treatment agent for human OSCC.
Subject(s)
Humans , Antineoplastic Agents , Pharmacology , Therapeutic Uses , Antineoplastic Combined Chemotherapy Protocols , Pharmacology , Therapeutic Uses , Apoptosis , Biphenyl Compounds , Pharmacology , Therapeutic Uses , Carcinoma, Squamous Cell , Drug Therapy , Cell Line, Tumor , Cell Proliferation , Cell Survival , Drugs, Chinese Herbal , Pharmacology , Therapeutic Uses , Flow Cytometry , Fluorouracil , Pharmacology , Therapeutic Uses , In Situ Nick-End Labeling , Lignans , Pharmacology , Therapeutic Uses , Magnolia , Mouth Neoplasms , Drug Therapy , Phytotherapy , Plant Extracts , Pharmacology , Therapeutic UsesABSTRACT
<p><b>AIM</b>To investigate the effect of DAPT (gamma-secretase inhibitor) on the growth of human tongue carcinoma cells and to determine the molecular mechanism to enable the potential application of DAPT to the treatment of tongue carcinoma.</p><p><b>METHODOLOGY</b>Human tongue carcinoma Tca8113 cells were cultured with DAPT. Cell growth was determined using Indigotic Reduction method. The cell cycle and apoptosis were analyzed by flow cytometry. Real-time PCR and Immuno-Fluorescence (IF) were employed to determine the intracellular expression levels.</p><p><b>RESULTS</b>DAPT inhibited the growth of human tongue carcinoma Tca8113 cells by inducing G0-G1 cell cycle arrest and apoptosis. The mRNA levels of Hairy/Enhancer of Split-1 (Hes-1), a target of Notch activation, were reduced by DAPT in a dose-dependent manner. Coincident with this observation, DAPT induced a dose-dependent promotion of constitutive Caspase-3 in Tca8113 cells.</p><p><b>CONCLUSION</b>DAPT may have a therapeutic value for human tongue carcinoma. Moreover, the effects of DAPT in tumor inhibition may arise partly via the modulation of Notch-1 and Caspase-3.</p>