This study evaluated cell viability and cytokine release in immortalized human oral fibroblasts (hTERT-hNOFs) and keratinocytes (IHOK) exposed to a dental-impregnated gingival retraction cord. To prepare the extracts, dental gingival retraction cords impregnated with aluminum chloride hexahydrate were immersed in a cell culture medium for 24 h at 37 °C. hTERT-hNOFs and IHOK were cultured for 24 h. The cell culture medium was removed and extracts of the dental gingival retraction cords were added. After incubation with the extract solution, cell viability was evaluated using an MTT assay. The levels of the cytokines IL-1α and IL-8 were measured in the supernatants of each cell type. The cell viability after exposure to the extract solution for 10 min exceeded 70 % in both cell types. The ET50 values for hTERT-hNOF and IHOK were 35.75 and 28.98 min, respectively. For IHOK, the IL-1α level was (5.35 ± 5.22) pg/mL at 10 min, (3.58 ± 5.38) pg/mL at 20 min, and (2.85 ± 4.28) pg/mL at 60 min of exposure (p > 0.05). The IL-8 level in IHOK was (67.16 ± 18.70) pg/mL at 10 min, (78.36 ± 7.50) pg/mL at 20 min, and (111.9 ± 26.10) pg/mL at 60 min of exposure (p > 0.05). Cytokine release was not observed from hTERThNOFs. Based on these results, cell viability and cytokine release were confirmed in cells exposed to the impregnated gingival retraction cord. In addition, the application of the extracts to hTERT-hNOF and IHOK during the actual contact time and determination of ET50 may be beneficial for evaluating the biocompatibility of dental-impregnated gingival retraction cords.

Repetitive or excessive exposure to ultraviolet (UV) radiation causes oxidative stress-mediated skin photoaging through the overproduction of reactive oxygen species. Actinidia polygama is known as a medical plant used in oriental medicine for treating several diseases such as abdominal pain, stroke and rheumatoid arthritis. Recently, it was reported that A. polygama extract had anti-wrinkle and skin hydrating properties in ultraviolet B (UVB)-exposed hairless mice. However, the molecular biological mechanism of this extract on alleviating skin photoaging is still unknown. Therefore, we investigated the anti-photoaging effects of PB203, which is the powder of A. polygama extract, in the in vivo and in vitro photoaging models. First, PB203 showed 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities due to the presence of anti-oxidant components including flavonoids and polyphenols. In UVB-irradiated hairless mice, oral administration of PB203 (100 mg/ kg) significantly improved wrinkle formation, skin dehydration, elasticity and skin barrier function by decreasing the levels of matrix metalloproteinases (MMPs) and increasing those of collagen I, filaggrin, involucrin and loricrin. Especially, the reduced production of p-p38, p-c-Jun and p-c-Fos by PB203 reversed the elevated levels of MMPs mediated by UVB exposure, resulting in the upregulation of collagen I expression. Consistent with these animal data, PB203 remarkably enhanced the mRNA expression of collagen I, filaggrin, involucrin and loricrin, while suppressed that of MMPs in UVB-irradiated HaCaT cells. And PB203 increased the wound recovery rate of cells by promoting their proliferation and migration. Moreover, PB203 significantly recovered the activity of superoxide dismutase inhibited by UVB in both mice and cells. In conclusion, PB203, which protects skin from UVB-induced photodamage by exerting antioxidant properties, can be considered to have sufficient potential as a functional ingredient or therapeutic agent improving skin photoaging and related skin symptoms.

Immortalization is an essential process of the transformation of cells to a neoplastic growth. High risk human papillomavirus (hrHPV) infection has been the major cause of head and neck squamous cell carcinoma (HNSCC). The aim of this study was to search for a novel pathway causing immortalization in HPV16 E6/E7 transfected immortalized oral keratinocytes (IHOK). hrHPV integration sites were identified through DNA sequencing. HPV16 E6/E7 genes were integrated into 1q32.2, 12q21.2, 15q15.2, and 19q13.43 in IHOKs. Array-CGH was conducted to examine the deranged sites of the genes of IHOK. Of the 587 amplification genes, 70 genes were resided on chromosome 20. We selected PLAGL2 and MAPRE1 as the most amplified genes. PLAGL2 and MAPRE1 mRNA showed higher expression in IHOK than in normal keratinocytes. Knockdown of MAPRE1 significantly reduced telomerase activity. The analysis using a public database substantiated our data, showing the amplification of chromosome 20 and MAPRE1. In conclusion, our results suggest that MAPRE1 could play a crucial role in activating telomerase activity in hrHPV-infected cells. This finding may provide basic data to develop a novel target therapy for hrHPV-related HNSCC.

Mushroom is known for anti-inflammatory and anti-oxidative potential. This study provides evidence that theinhibitory effect of mushroom on the expression of pro-inflammatory cytokines in human keratinocytes, HaCaT cells. To definethe underlying mechanisms of action, tumor necrosis factorα/IFNγ-activated human keratinocytes model was used. Mushroomsignificantly inhibited the expression of cytokines in HaCaT cells. Taken together, the results demonstrate that mushroom inhibitedinflammtion, suggesting that mushroom (DW extract: Grifola frondosa Cordyceps militaris), (Ethanol extract: Ganoderma lucidum,Lentinus edodes, Cordyceps militaris, Flammulina velutipes) might be a candidate for the treatment of skin inflammation.

The aim of this study was to determine the beneficial effect of propofol on human keratinocytes that have undergone hypoxia reoxygenation (H/R) injury and to investigate whether autophagy is associated with the protective mechanism. Thus, we evaluated how propofol influences the intracellular autophagy and apoptosis during the H/R process in the HaCaT cells. The cultured human keratinocyte cells were exposed to 24 h of hypoxia (5% CO2, 1% O2, 94% N2) followed by 12 h of reoxygenation (5% CO2, 21% O2, 74% N2). The experiment was divided into 4 groups: (1) Control=Normoxia ; (2) H/R=Hypoxia Reoxygenation ; (3) PPC+H/R=Propofol Preconditioning+Hypoxia Reoxygenation; (4) 3-MA+PPC+ H/R=3-MA-Methyladenine+Propofol Preconditioning+ Hypoxia Reoxygenation. In addition, Western blot analysis was performed to identify the expression of apoptotic pathway parameters, including Bcl-2, Bax, and caspase 3 involved in mitochondrial-dependent pathway. Autophagy was determined by fluorescence microscopy, MDC staining, AO staining, and western blot. The H/R produced dramatic injuries in keratinocyte cells. In our study, the viability of Propofol in H/R induced HaCaT cells was first studied by MTT assay. The treatment with 25, 50, and 100 μM Propofol in H/R induced HaCaT cells enhanced cell viability in a dose-dependent manner and 100 μM was the most effective dose. The Atg5, Becline-1, LC3-II, and p62 were elevated in PPC group cells, but H/R-induced group showed significant reduction in HaCaT cells. The Atg5 were increased when autophagy was induced by Propofol, and they were decreased when autophagy was suppressed by 3-MA. These data provided evidence that propofol preconditioning induced autophagy and reduced apoptotic cell death in an H/R model of HaCaT cells, which was in agreement with autophagy playing a very important role in cell protection.

Propionibacterium acnes (P. acnes) cause an inflammatory acne that plays an important role in the pathogenesis of acne by inducing inflammatory mediators. Bee venom therapy has been used in oriental medicine for the relief of pain and the treatment of inflammatory diseases. However, a direct effect of bee venom in skin inflammation has not been established. The purpose of this study was to investigate anti-inflammatory properties of bee venom in skin inflammation stimulated by heat-killed P. acnes using human keratinocytes and monocytes cell line. P. acnes stimulates the production of proinflammatory cytokines such as interleukins-1β, -8, interferon-γ and tumor necrosis factor-α in HaCaT and THP-1 cells. Bee venom effectively inhibits the secretion of IL-1β, IL-8, IFN-γ, and TNF-α. P. acnes treatment activates the expression of TLR2, which results in IL-8 expression. However, bee venom treatment reduces the expression of TLR2 and IL-8. Based on these results, bee venom has effects on anti-inflammatory activity against P. acnes in HaCaT and THP-1 cells.

Cellular microenvironment is an essential issue for regulating epithelial characteristics through the alteration of intricate signaling pathways and intercellular communications in different cell types. Thus, microenvironment influences tumor initiation, progression, and metastasis. This study aimed to investigate the relationship between microenvironment and epithelial property in HPV16 E6/E7-immortalized human oral keratinocytes (IHOKs). To investigate characteristics of IHOK cultured in different media, two media were used, which included keratinocyte growth media (KGM), F-medium composed of 3:1 ratio of DMEM and F-12 (P media) supplemented with 10% FBS and 1% penicillin/streptomycin. Proliferative property and invasive and migratory activity were observed. As results, proliferating activities of IHOK in different culture condition were changed. Likewise, migratory and invasive activities were also different depending on media types. These results suggest that cellular microenvironment can affect modification of biological properties of epithelial cells.

MicroRNAs (miRNAs) are small non-coding RNAs that mediate gene expression at the post-transcriptional level by degrading or repressing targeted mRNAs. These molecules are about 21-25 nucleotides in length and exert their effects by binding to partially complementary sites in mRNAs, predominantly in the 3'-untranslated region (3'-UTR). Recent evidence has demonstrated that miRNAs can function as oncogenes or tumor suppressors through the modulation of multiple oncogenic cellular processes in cancer development, including initiation, cell proliferation, apoptosis, invasion and metastasis. In our present study, we examined the expression profile of miRNAs related to oral cancer cell growth inhibition using normal human oral keratinocytes (NHOK) and YD-38 human oral cancer cells. By miRNA microassay analysis, 40 and 31 miRNAs among the 1,769 examined were found to be up- and down-regulated in YD-38 cells compared with NHOK cells, respectively. Using qRT-PCR analysis, the expression levels of miR-30a and miR-1246 were found to be increased in YD-38 cells compared with NHOK cells, whereas miR-203 and miR-125a were observed to be decreased. Importantly, the overexpression of miR-203 and miR-125a significantly inhibited the growth of YD-38 cells. This finding and the microarray data indicate the involvement of specific miRNAs in the development and progression of oral cancer.

Considering the great potential of iron chelators at inhibiting the proliferation of tumor cells, in order to determine the molecular and biological basis for the effects of iron chelator in oral cancer, we investigated the effects of iron chelator, desferrioxamine (DFO), on the gene profiling analysis of immortalized human oral keratinocytes (IHOK), and oral cancer cells (HN12), using the cDNA microarray. We identified 46 clones cDNA exhibiting more than 2 fold overexpression in DFO treated IHOK and HN12 cells, and 94 cDNA reveal more than 2 fold down-regulated expression. Examination of gene expression that differs between DFO treated vs. control IHOK and HN12 cells apprear to be related to : cell cycle regulator, cell growth and apoptosis, signal transduction and stress. p21 for cell cell cycle factor was upregualted, and cyclin-cdk gene was decreased expression, so we observed cell cycle arrest in DFO treated IHOK and HN12 cells. In tumor growth, we have identified downregulation of hemidesmosomal protein (bullous pemphigoid antigen 1) and epiregulin expression in DFO treated IHOK and oral cancer cells. Signal transducers including mitogen-activated protein kinase-activated protein kinase 5, serine/thereonine kinase 6 were downregulated with DFO treated cells, suggesting the DFO regulates the p38 MAP kianse pathway in immortalized and maignant oral keratincytes. In conclusion, we have demonstrated the high-throughput utility of cDNA array hybridization in parallel to the gene expression analysis to identify genes that are expressed differentially in DFO treated with immortalized and malignant oral keratinocytes. The differentially expressed genes identified here should be informative in DFO-induced anti-cancer effects.

The prominent side effect of cyclosporin A, immunosuppressive agent, in oral tissues is gingival overgrowth(GO). It is characterized by the gingival enlargement with epithelial thickening, a large number of proliferating fibroblasts and overproduction of ECM components. Fibroblast accumulation in Cs A induced GO is caused by the Inhibition of apoptosis. But CsA effect on normal human oral keratinocyte(NHOK) remains unclear. Transglutaminase 2(TGase 2) which is expressed and activated in tissue where epithelial cells undergo apoptosis has been used as a marker for apoptotic cells. The purpose of this study were to study the effect of CsA on the proliferation and apoptosis of cultured NHOK by TGase 2 expression. After primary cultured NHOK was treated by 0.1, 1.0 and 10ug/ml Cs A, growth curve, MTT assay for succinyl dehydrogenase activity and RT-PCR for TGase 2 mRNA expression were done. The obtained results were as follows. MTT assay showed about 65% cell viability at 1.0μg/ml and 40% at 10μg/ml CsA. Growth curve showed normal S curve on control & DMSO, while decreased growth rate after 3 days of higher CsA tx. TGase 2 mRNA expression of cultured NHOK was the highest at 10μg/ml Cs A. TEM showed chromosome margination, and vacuole formation and clustered mitochodria in cytoplasm of cultured NHOK after CsA tx. It suggested that higher CsA might induce apoptosis of NHOK correlated with increased TGase 2 mRNA expression

Macrophage inflammatory prote in -3α (M1P-3a 01' CCL20) is an intr땅uing molecule in CanCel‘ irrununotherapy‘ but M1P-3 a expr ession and signaling are not well under s tood in oral cancer cell s. We investigated CCL20 expression a nd signal trans duction by treating immortal ized hllman oral keratinocyte (IHO찌 and oral ca ncer (뻐 4) cells with defe roxa llline (DFO) and examined the mRNA express ion 01' CCL20 using RT- PCR and ELI8A. lHOK and HN4 cells treated with DFO sbowed increased mRNA and protein expression 01' CCL20. and the upregulation 01' DFO-induced CCL20 expression was higher in IHOK cells than in HN4 cells 8elective inhibitors of p38 and ERKl/2 abol ished DF'O- induced CCL20 expression in both lHOK and HN12 cells. and p38 and ERKl/2 inhibitors prevented DFO- induceddegradati on 01' 1 -κ B and NF'-K B activation. Activation 01' c-fos and c-jun also occmred fo l lowing DFO treatment in IHOK and HN4 cells Collectively, these results suggest that DFO-indllced M1 P- 3a. which is involved in the MAP kinase‘ c-fos, c-jun, and NF-K B pathways, may be an important mediator of the a ntitumor immune response in oral keratinocytes ancl warrants con sideration as a target molecule for oral cancer t reatment

Heme oxygenase-l (HO-l) exhibits cyt oprotective effects in many different cell types and is induced by nicotine exposure in human gingival fibroblasts‘ However‘ therole of HO- l in cancer cells exposed to nicotine has not previously been descnbed We investigated the effects of nicotine on HO-l protein expression and cell viability in immortalized (IHOK) and malignant (HN12) human ora l keratinocyte cells using the MTT assay and Western blotting. We al so examined the involvement of t he phosphoinosit ide-3-0H- kinase (PI3K), mitogen-acti vated protein kinase (MAPK) , and nucJear factor-κ B (NF-κ B) signaling pathways in nicotine-induced cytotoxicity and HO- l levels in IHOK and HN12 cell s‘ Nicotine induced HO- l pro ducti on and had cytotoxic effects on cells in both a concentration- and time-dependent manner. Nicotine-induced cytotox icity and accumulation of HO- l were greater in JJ-IOK cells than in HN12 cells Molecular inhibitors of the ERK, p38 MAP kinase, PI3K, and NF-κ B signaling pathways blocked the cytotoxic effects and induction of J-IO-l expression by nicotine. Treatmen t with an t ioxida nts (bil irubin, N-acetyl cysteine) protected cells against nicotine-induced cytotoxicity and blocked the upregula tion of J-IO- l, the effects of which were more pronounced in II-IOK cells than in HN12 cells Collecti vely, these results suggest that J-IO- l plays a principal role in the protective response to nicotine in oral cancel and immortalized keratinocytes. Moreover, the addition of exogenous antioxidants may help to protect oral epithelial cells as chemopreventive agents against nicotine-induced oxidative stress.

Heme oxygenase-l (HO-l) exhibits cyt oprotective effects in many different cell types and is induced by nicotine exposure in human gingival fibroblasts‘ However‘ therole of HO- l in cancer cells exposed to nicotine has not previously been descnbed We investigated the effects of nicotine on HO-l protein expression and cell viability in immortalized (IHOK) and malignant (HN12) human ora l keratinocyte cells using the MTT assay and Western blotting. We al so examined the involvement of t he phosphoinosit ide-3-0H- kinase (PI3K), mitogen-acti vated protein kinase (MAPK) , and nucJear factor-κ B (NF-κ B) signaling pathways in nicotine-induced cytotoxicity and HO- l levels in IHOK and HN12 cell s‘ Nicotine induced HO- l pro ducti on and had cytotoxic effects on cells in both a concentration- and time-dependent manner. Nicotine-induced cytotox icity and accumulation of HO- l were greater in JJ-IOK cells than in HN12 cells Molecular inhibitors of the ERK, p38 MAP kinase, PI3K, and NF-κ B signaling pathways blocked the cytotoxic effects and induction of J-IO-l expression by nicotine. Treatmen t with an t ioxida nts (bil irubin, N-acetyl cysteine) protected cells against nicotine-induced cytotoxicity and blocked the upregula tion of J-IO- l, the effects of which were more pronounced in II-IOK cells than in HN12 cells Collecti vely, these results suggest that J-IO- l plays a principal role in the protective response to nicotine in oral cancel and immortalized keratinocytes. Moreover, the addition of exogenous antioxidants may help to protect oral epithelial cells as chemopreventive agents against nicotine-induced oxidative stress.

Sulfur is commonly used in Asia as a n herba l medicine to treat infl ammation and cancel‘. and potent chemopreventive effects have been demonstrated in various in vivo and in vitromodels for sulfur-containing compounds found in naturally occun‘ ing products. Here, we report the growth inhibitory and apoptosis-related effects of a newly developedhigh- purity eclible sulfur (ES) on immortali zecl human oral keratinocytes (IHOKs) and on oral cancer cells representing two stages of oral can cer (HN4‘ HN12) basecl on an 3-(4. 5-Dimethylt hiazol-2-yl)-2.5-cliphenyl tetrazolium bromide (MTT) a ssay, Western blotting, cell cycle analysis, ancl nuclear staining. The puri ty of the ES used in th is s tucly was verified by high performance liquid chromat ography (HPLC) , amino acid analysis and energy di spersive spectroscopy (EDS). ES inhibitecl the proliferation of immor talized and malignant oral kerati nocytes in a dose- and time-dependent manner FITC-Annexin V staining. DNA fragmentation testing. and Hoechst 33258 staining revealed that ES inhibits cell growth via apoptosis . ES blocked cell-cycle progression at the sub- Gl phase, with decreased expression 0 1' cyclins Dl, D2, and E, and t heir activating partners cdk2, cdk4, and cdk6‘ and a concomitant induction of p53 and p21/WAF1. Furthermore, ES treatment increased the cytosolic level of cytochrome c a nd resulted in caspase-3 activation‘ and thi s effect was correlated wi th Bax up- regulation and Bcl-2 down- regulation Taken together, these clata suggest that ES is a potential chemopreventive and chemotherapeutic agent for oral cancel

Cell behavior of the transformed cells is known to affect by interaction with extracellular matrix (ECM) proteins and integrin. To investigate the alterations of both integrin expression and cell-matrix interaction during neoplastic conversion of human oral kerationcytes, we studied expression levels of integrin subunits by flow cytometry and cellular responses to the ECM proteins in normal human oral keratinocytes (NHOKs), HPV-immortalized HOK-16B line, and three oral cancer cell lines established from HOK-16B line, CTHOK-16B-BaP, CTHOK-16B-DMBA, and CTHOK-16B-Dexa lines. The expression levels of α and β integrin subunits were shown decreased tendency in human oral keratinocytes undergoing immortalization and tumorigenic transformation except CTHOK-16B-DMBA line tested. Although αuβ6 integrin is known to be highly expressed in squamous cell carcinomas, and the altered integrin expression is suspected to be associated with cellular carcinogenesis, αu integrin subunit and αuβ6 egrin did not express in oral cancer cell lines tested. Cell behavior to the ECM proteins in HOK-16B line was generally similar to that of exponentially proliferating NHOKs. The adhesion activity profiles of type I collagen were very similar to that of its laminin counterparts, but fibronectin showed minimal adhesion activity under our conditions compared to the BSA control. The ability of the CTHOK-16B-BaP line to spread upon type I collagen and laminin markedly decreased, but migration was notably increased on type I collagen. In contrast, CTHOK-16B-DMBA and CTHOK-16B-Dexa lines spread less but migrated more upon type I collagen than immortalized HOK-16B line. These data indicate that downregulation of integrin subunits causes the changes of cellular responses to the ECM proteins during neoplastic conversion of human oral keratinocytes, and that cellular responses to the ECM proteins in oral cancer cell lines established by exposing different carcinogens are variable according to chemical carcinogens treatment.

We have examined the effect of NO donor, S-nitl‘ oso-N-acetyl-DL-penicillamine(SNAP) on heme oxygenase-1 (HQ-l) ex pression in human oral immortalized & malignant keratinocytes, and investigated in the control of keratinocyte proliferation evidence tha t HO-1 cou ld be involved in a low dose of NO, NO inhibitor, HOinducer, and HO inhibitor medi ated cytoprotect ion against cytotoxi city induced by a high dose of NO Oral keratinocyte growth inhibitory or anti-proliferative effects were exerted by with SNAP and hemin in a dose- and cul tivation time dependent manner The level of HQ-1 protein was increased in all cell types after exposure hernin dose, and the hemin induced HQ-1 protein achieved at higher maximum level by 12 hrs in all kind of cells , The pretreatment of cells with 0, 2 μ M SNAP reduced 1 mM SNAP-induced death in IHOK and HN4 cells , These cytoprotective effects on high dose of NO induced HQ-1 expresion and cell ular toxicity were blocked by low dose of SNAP, HCB, and ZnPP IX supporting the involvement of HQ-1 in high dose NO induced growth arrest or cell death, But these cytoprotection pattern is different from immortalized and malignant keratinocytes , These results indirectly demonstrate that HQ-1 could be involved in cytoprotection by NO priming against high dose NO induced cytotoxicity in immortalized and maigla nt oral keratinocytes, Thus, HQ-1 might be an important cellular target of NO donor, with clinical implications for the pre vention of inJlammatory di seases and anti-tumor immunity

Sulfur is commonly used in Asia as an herbal medicine to treat inflammation and cancer , a nd potent chemo preventi ve effects have been demons tra ted in various in vivo and in vitromodels for s ul fur-containing compounds found in natura l1y occurring product s. Here, we 1'eport the growth inhibitory and apoptosis-related effects of a n ewly developedhigh-puri ty edible sulfur(ES) on immo1'tali zed human o1'al ke1'atinocytes(IHOKs) and on oral cancer cells representing two stages of oral cancer (HN4‘ HN12) based on an 3-(4,5-Dimethylthiazol-2-yl) -2.5- diphe n yltetrazolium bromide(MTI) assay, Western blotting, cell cycle analysis, and nuclear staining. The puri ty of the ES used in thi s study was ve1'ified by high performance liquid chromatog1'aphy (HPLC) , ami no acid analysis and energy dispersive spectroscopy(EDS). ES inhibited the prolife1'ation of imrnortalized and ma lig nant o1'al kerati nocytes in a dose- and time-dependent manne1' FITC-Annex.in V staining, DNA fragmentation t esting. and Hoechst 33258 s taining revealed that ES inhibits cell growth via apoptosis. ES bl ocked cell-cycle prog1'ession at t he sub-Gl phase‘ wi th decreased expression of cyclins Dl, D2‘ and E, and their activating partn ers cdk2‘ cdk4‘ and cdkfì, and a concomitant induction of p53 and p21/WAF1. Furthe1'more, ES treatment in creased the cytosolic level of cytochrome c and resulted in caspase- 3 activation‘ and thi s effect was co1'1'elated with Bax up-regulation and Bcl-2 down-1'egulation Taken together‘ these data suggest that ES is a potential chemopreventive and chemotherapeut ic agent fo r oral ca ncer

1'0 determine Lhe ll1echanism of cell c1eath incluced by iron chelators. we explored the pathways of the three structurally relatecl ll1 itogen-activatecl protein(MAP) kinase subfami li esduring iron cbelator- inclucecl apoptosis ancl differentiation of oral precancerous ancl cancel‘ cells. The iron chelator c1 eferoxamine(DFO) exertecl potent timeancl c1ose-c1epenclent inhi bitory effects on the growth of IHOK and HN4 cells The major mechanism of growth inhibition following DFO treatment was fOllncl to be apoptosis incluction. as assessecl by annexin V-FITC staining. cell cycle analysis‘ DNA lacldering, a ncl Hoechst staining. We report that DF'O s trongly activates the p38 MAP kinase and extracell ular signal- regu lated kinase(ERK). but c10es not activate the c-Jun N-terminal kin ase/ stl않s-activaLecl protein kinase(JNK/8APK) . Of the three MAP kinase blockers usecl‘ the selective p38 MAP kinase inhibitor 8ß203580 ancl ERK inhibitor PD98059 protected oral premaIignant ancl malignant cells againsL iron chelator- nclllced cell death. which incl icates that the p38 MAP kinase serves as a major mecliator 01' apoptos is induced by this iron chelator DFO also evoked the release of cytochrome c from mitochondria, and incluced the activation of caspase-3 ancl caspase-8 in oral cancer cells, which suggests that apoptosis occurs via the mi tochoncl ri on - mecl iaLed pathway. DFO enhanced the expression of Bax in IHOK ancl HN4 cells. consistent witll thei r p53 status Moreover. DFO downregulatecl the expression 01' Bcl-2 in oral cancer cells. which suggests that DFO- incluced apoptos is 01' oraJ cancer and precancerous cells may be mediatecl by an increase in the ratio of pro-apoptotic to anti-apoptotic proteins. ln terestingJy, trcatmcnt 01' IHOK ancl HN4 cel ls with 8B203580 abolishecl cytochrome c release‘ as wel l as the activation of caspase-3 and caspase-8. DFO suppressecl the expression of epithelial di ffe rentiation markers, such as involucrin, t ransglutaminase II. CK6. and CK19. ancl this suppression was blockecl by p38 ancl ERK MAP kinase ll1hlbltors The oral premalignant(IHOK) ancl malignant cell s(I-lN4) showed differential responses to DFO with respect to the expression of cel l cycle regulatory proteins. cell growth. ancl apoptosis. Coll ectively. the current study reveals that p38 MAP kinase plays an ill1 portant role in iron chela tor-mecliatecl cel l cleath and in the suppression of differentiation of oral premalignantandmalignanLcell s.by activating a c10wnstream apoptotic cascade that executes the ceIl c1eath pathway