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.

Iron chelator differentially activates macrophage inflammatory protein-3alpha/CCL20 in immortalized and malignant human oral keratinocytes.

Macrophage inflammatory protein-3alpha (MIP-3alpha or CCL20) is an intriguing molecule in cancer immunotherapy, but MIP-3alpha expression and signalling are not well understood in oral cancer cells. We investigated CCL20 expression and signal transduction by treating immortalized human oral keratinocyte (IHOK) and oral cancer (HN4) cells with deferoxamine (DFO) and examined the mRNA expression of CCL20 using RT-PCR and ELISA. IHOK and HN4 cells treated with DFO showed increased mRNA and protein expression of CCL20, and the upregulation of DFO-induced CCL20 expression was higher in IHOK cells than in HN4 cells. Selective inhibitors of p38 and ERK1/2 abolished DFO-induced CCL20 expression in both IHOK and HN12 cells, and p38 and ERK1/2 inhibitors prevented DFO-induced degradation of I-kappaB and NF-kappaB activation. Activation of c-fos and c-jun also occurred following DFO treatment in IHOK and HN4 cells. Collectively, these results suggest that DFO-induced MIP-3alpha, which is involved in the MAP kinase, c-fos, c-jun, and NF-kappaB pathways, may be an important mediator of the antitumour immune response in oral keratinocytes and warrants consideration as a target molecule for oral cancer treatment.

Smartphone use and schema-based learning in dentomaxillofacial radiology practice: a case report from one College of Dentistry.

OBJECTIVES: This study investigates the students' satisfaction and awareness of competency towards smartphone use and schema-based learning in dental radiology practice. METHODS: Third year students undertaking a dental radiology practicum at a dental school were divided into two groups: one group received traditional clinical training, whereas the other group used smartphones in classes and received new training using schema assignments. At the end of the course, students' satisfaction with the training and self-awareness of their competency were surveyed, and their achievement was assessed. RESULTS: Although students' satisfaction with smartphone-based training was generally high, it was less than that of students trained by traditional instruction. However, most students that received smartphone-based training had higher self-scored competency before than after training. The smartphone group scored higher on true/false or multiple-choice questions, whereas the traditional group scored higher on short-answer questions. CONCLUSIONS: Smartphone education with schema based assignment proved to be attractive in dental radiology, but students showed less satisfaction, and need to meet the requirements of evidence-based practice. Although the full use of smartphone education with schema is not recommended in dental education, we think that it could be try to use as a supplementary approach with traditional didactic method to facilitate student's exploration and self-study to cope with rapid change in educational environment.