Anti-cancer activity of highly purified sulfur in immortalized and malignant human oral keratinocytes.
Sulfur is commonly used in Asia as an herbal medicine to treat inflammation and cancer, and potent chemopreventive effects have been demonstrated in various in vivo and in vitro models for sulfur-containing compounds found in naturally occurring products. Here, we report the growth inhibitory and apoptosis-related effects of a newly developed highly purified sulfur (HPS) on immortalized human oral keratinocytes (IHOKs) and on oral cancer cells representing two stages of oral cancer (HN4, HN12) based on a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Western blotting, cell cycle analysis, and nuclear staining. The purity of the sulfur preparation was verified by high-performance liquid chromatography. HPS inhibited the proliferation of immortalized and malignant oral keratinocytes in a dose- and time-dependent manner. FITC-annexin V staining, DNA fragmentation testing, and Hoechst 33258 staining revealed that HPS inhibited cell growth via apoptosis. HPS increased the sub-G1 cell cycle fraction, with decreased expression of cyclins D1, D2, and E and their activating partners cdk2, cdk4, and cdk6, and a concomitant induction of p53 and p21/WAF1. Furthermore, HPS treatment increased the cytosolic level of cytochrome c and resulted in caspase-3 activation; this effect was correlated with Bax up-regulation and Bcl-2 down-regulation. Thus, these data suggest that HPS is a potential candidate for anti-cancer therapy in oral cancer.
Lee
Jun
J
Department of Oral and Maxillofacial Surgery, College of Dentistry, Wonkwang University, Iksan, South Korea.
Lee
Hwa-Jeong
HJ
Park
Jong-Dae
JD
Lee
Sun-Kyung
SK
Lee
Sang-Im
SI
Lim
Hyun-Dae
HD
Lee
You-Mee
YM
Yun
Young-Gab
YG
Jeon
Byung-Hun
BH
Ree
In-Soo
IS
Jun
Chang-Duk
CD
Lee
Suk-Keun
SK
Kim
Eun-Cheol
EC
D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016213:Cyclins / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000473:pathology; D009062:Mouth Neoplasms / Q000188:drug therapy*; D009367:Neoplasm Staging; D013457:Sulfur Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D000970:Antineoplastic Agents; D016213:Cyclins; D013457:Sulfur Compounds