Oral bacterial infections substantially affect the development of various periodontal diseases and oral cancers. However, the molecular mechanisms underlying the association between Fusobacterium nucleatum (F. nucleatum ), a major periodontitis (PT)-associated pathogen, and these diseases require extensive research. Previously, our RNAsequencing analysis identified a few hundred differentially expressed genes in patients with PT and peri-implantitis (PI) than in healthy controls. Thus, in the present study using oral squamous cell carcinoma (OSCC) cells, we aimed to evaluate the effect of F. nucleatum infection on genes that are differentially regulated in patients with PT and PI. Human oral squamous cell carcinoma cell lines OSC-2O, HSC-4, and HN22 were used. These cells were infected with F. nucleatum at a multiplicity of infection of 100 for 3 hours at 37℃ in 5% CO2. Gene expression was then measured using reverse-transcription polymerase chain reaction. Among 18 genes tested, the expression of CSF3, an inflammation-related cytokine, was increased by F. nucleatum infection. Additionally, F. nucleatum infection increased the phosphorylation of AKT, p38 MAPK, and JNK in OSC-20 cells. Treatment with p38 MAPK (SB202190) and JNK (SP600125) inhibitors reduced the enhanced CSF3 expression induced by F. nucleatum infection. Overall, this study demonstrated that F. nucleatum promotes CSF3 expression in OSCC cells through p38 MAPK and JNK signaling pathways, suggesting that p38 MAPK and JNK inhibitors may help treat F. nucleatum-related periodontal diseases by suppressing CSF3 expression.

Oral squamous cell carcinoma (OSCC), which accounts for approximately 90% of oral cancers, has a high rate of local recurrence and a poor prognosis despite improvements in treatment. Exosomes released from OSCC cells promote cell proliferation and metastasis. Although it is clear that the biogenesis of exosomes is mediated by the endosomal sorting complex required for transport (ESCRT) machinery, the gene expression pattern of ESCRT, depending on the cell type, remains elusive. The exosomal release from the human OSCC cell lines, HSC-3 and HSC-4, and their corresponding gefitinib-resistant sub-cell lines, HSC-3/GR and HSC-4/GR, was assessed by western blot and flow cytometry. The levels of ESCRT machinery proteins, including Hrs, Tsg101, and Alix, and whole-cell ubiquitination were evaluated by western blot. We observed that the basal level of exosomal release was higher in HSC-3/GR and HSC-4/GR cells than in HSC-3 and HSC-4 cells, respectively. Long-term gefitinib exposure of each cell line and its corresponding gefitinib-resistant sub-cell line differentially induced the expression of the ESCRT machinery. Furthermore, whole-cell ubiquitination and autophagic flux were shown to be increased in gefitinib-treated HSC-3 and HSC-4 cells. Our data indicate that the expression patterns of the ESCRT machinery genes are differentially regulated by the characteristics of cells, such as intracellular energy metabolism. Therefore, the expression patterns of the ESCRT machinery should be considered as a key factor to improve the treatment strategy for OSCC.

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer and is associated with high recurrence, poor treatment, and low survival rates. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that regulates the response to hypoxia, a major factor in the tumor microenvironment that affects tumor development and progression in various cancer types. However, microRNA (miRNA) sequence analysis revealed that only a few miRNAs targeting HIF-1α had been discovered. In the present study, we investigated HIF-1α expression in OSCC and the effect of HIF-1α-targeting miRNAs on the progression and metastatic potential of OSCC. We analyzed public databases to explore which miRNAs target HIF-1α expression. In addition, the expression of proteins involved in the cell cycle, proliferation, and apoptosis in HSC-2 cells was analyzed after miRNA-126 mimic treatment. Furthermore, to investigate the effect of miRNA-126 on the proliferation and invasion ability of OSCC cells, 5-ethynyl-2′-deoxyuridine and Transwell assays were performed. The activities of MMP-2 and MMP-9 were evaluated via gelatin zymography. Our results showed that miRNA-126, which targets HIF-1α, enhances OSCC cell proliferation by regulating the cell cycle and reinforces the cell mobility of OSCC via HIF-1α expression. These findings suggest that miRNA-126 may be a novel marker for OSCC treatment and the development of new tools for patients with OSCC.

Resveratrol has been reported to exert anticancer activity via modulation of multiple pathways and genes. In this study, we examined the effect of resveratrol on YD-10B human oral squamous cell carcinoma cells and its molecular mechanisms of action. We found that resveratrol inhibited the proliferation of YD-10B cells in a dose- and timedependent manner. The suppressive effect of resveratrol was accompanied by a reduction in Bmi-1 gene expression. We observed that silencing the Bmi-1 gene by small interfering RNA effectively downregulated the levels of GLUT1 mRNA and protein, which were also repressed by resveratrol. Bmi-1 silencing increased the number of YD-10B cells in S-phase arrest by approximately 2.3-fold compared with the control. In conclusion, the results of the present study demonstrate, for the first time, that resveratrol suppresses Bmi-1-mediated GLUT1 expression in human oral squamous cell carcinoma cells and suggest that the specific molecular targeting of Bmi-1 and/or GLUT1 expression can be combined with a chemotherapeutic strategy to improve the response of oral cancer cells to resveratrol.

Recently chronic inflammation is focused on the association with cancer progression and acquisition of aggressive biologic behaviors, such as invasion, metastasis, and resistance to chemotherapeutic reagents. Due to the close vicinity within oral cavity, oral cancer may be intimately associated with chronic periodontitis. The present study was done to observe the effect of chronic periodontitis on oral cancer cells by utilizing P. gingivalis infection, a major pathogen in chronic periodontitis. We analyzed and compared the mRNA expression levels of epithelial-mesenchymal transition (EMT) markers in non-infected and P. gingivalis-infected oral cancer cells. Eighty-six genes, which are well known as EMT markers, were analyzed using commercially available EMT microarray plates, performed in triplicate. Among the 86 genes, the expression of 26 was increased (≥ 2 fold) by P. gingivalis, whereas that of 7 genes was decreased (≥ 2 fold). Our study suggests that P. gingivalis infection evokes significant changes in EMT-related genes. Further observations on molecular mechanisms underlying these changes may help to clarify the role of chronic periodontitis on cancer progression and to develop more efficient preventive and therapeutic modalities for oral cancer. (182 words)

The role of CXCR7, a seven-transmembrane G-protein coupled chemokine receptor, which binds with high affinity to chemokine CXCL11 and CXCL12 in oral cancer cells and the effect of transient CXCR7-downregulation on proliferation and migration of oral squamous cell carcinoma (OSCC) cells have not been reported. The aim of the present study was to evaluate the effects of CXCR7 on an OSCC cell line. In this study, we down-regulated CXCR7 in the KOSCC25B OSCC cell line by siRNA. In vitro cell proliferation and migration assays were used to investigate the effect of CXCR7- downregulation on cell proliferation and migration in si.KOSCC25B cells. The CXCR7 down-regulated OSCC cells grew significantly slower than the negative control siRNA transfected KOSCC25B cells (p<0.05). Additionally, migration of si.KOSCC25B cells decreased significantly compared with non-transfected KOSCC25B cells (p<0.007). These results suggest that down-regulation of CXCR7 induces anti-proliferative and anti-migratory effects in OSCC, and that CXCR7 may be a useful target molecule for the treatment of OSCC.

The fruit of Kochia scoparia Scharder is traditionally used as a medicinal ingredient to treat allergic skin diseases and inflammatory diseases in China, Japan and Korea. Recently, several studies reported that K. scoparia had potential for the cytotoxicity of human cancer cells. To investigate the anti-cancer effect of K. scoparia on oral cancer and to determine the specific type of cell death induced by MEKS treatment. We investigated the anti-cancer effects of K. scoparia, methanol extract (MEKS) in HSC4 human oral cancer cells. We examined the effects of MEKS on the proliferation rate, cell cycle arrest, 7-AAD-ANNEXIN V double stain, reactive oxygen species (ROS) generation and activation of apoptosis and necroptosis-associated proteins in HSC4 cells. MTT assay results demonstrated that MEKS decreased the proliferation rates of HSC4 cells in a dose-dependent manner with an IC50 value of 45.3 μg/ml. MEKS at 50 μg/ml significantly increased the sub-G1 DNA contents of HSC4 cells to 84.8%, versus untreated cells. However, the activation of apoptosis-associated proteins such as cleaved caspase 3, cleaved caspase 8, cleaved caspase 9 and cleaved Poly (ADP-ribose) polymerase (PARP) did not detect. The level of Bax protein markedly increased in MEKS-treated HSC4 cells. In addition, the cell viability of the DPQ pre-treated HSC4 cells with MEKS treatment was significantly greater than that of MEKS treated-cells. These results suggest that MEKS inhibits cell proliferation and induces necroptosis in oral cancer cells and that MEKS may have potential chemotherapeutic value for the treatment of human oral cancer.

OSCC is currently the most common malignancy of the head and neck, affecting tens of thousands of patients per year worldwide. Natural flavonoids from plants are potential sources for novel anti-cancer drugs. Icariin is the active ingredient of flavonol glycoside, which is derived from the medical plant Herba Epimedii. A metabolite of icariin, icariside II exhibits a variety of pharmacological actions, including anti-rheumatic, anti-depressant, cardiovascular protective, and immunomodulatory functions. However, the exact mechanism causing the apoptosis-inducing effect of icariside II in OSCC is still not fully understood. In the present study, we assessed the anti-cancer effect of icariside II in OSCC cell lines by measuring its effect on cell viability, cell proliferation, and mitochondria membrane potential (MMP). Icariside II treatment of OSCC cells resulted in a dose- and time-dependent decrease in cell viability. Hoechst staining indicated apoptosis in icariside II-treated HSC cells. Icariside II inhibited cell proliferation and induced apoptosis in HSC cells, with significant increases in all present parameters in HSC-4 cells. The results clearly suggested that icariside II induced apoptosis via activation of intrinsic pathways and caspase cascades in HSC-4 cell lines. The collective findings of the study suggested that Icariside II is a potential treatment for OSCC; in addition, the data could provide a basis for the development of a novel anti-cancer strategy.

Chronic inflammation is widely considered to predispose individuals to cancer. Microorganisms facilitate recruitment and activation of inflammatory cells and thus allow release of inflammatory mediators. These molecules can then promote accumulation of mutations, leading to tumor development in the host. Porphyromonas gingivalis, a pathogen causing chronic periodontitis, is detected in oral squamous cell carcinoma (OSCC) tissues. Considering a strong link between chronic inflammation and tumor development, functional consequences of P. gingivalis infection may include malignant transformation of the host cells. In this study, we monitored transcriptional changes induced by invasion of P. gingivalis in OSCC cells using microarrays. Our preliminary results suggest changes in a wide range of genes involved in inflammation, apoptosis and autophagy, tumor progression, and carcinogenesis. Further studies on molecular mechanisms underlying these changes will lay a useful foundation to elucidate the role of microorganism-related inflammation and for the development of preventive and therapeutic agents for oral cancer.

The use of bacteria in the treatment of cancer has a long and interesting history. The use of live bacteria in this way however has a number of potential problems including toxicity. Purified low molecular weight bacterial proteins have therefore been tested as anticancer agents to avoid such complications. Oral cancer is a widely occurring disease around the world and these lesions are typically very resistant to anticancer agents. In our present study we investigated the effects of purified recombinant azurin from Pseudomonas (P.) aeruginosa against YD-9 (p53-positive) human oral squamous carcinoma cells. Azurin showed cytotoxic effects against these cells in a dose dependent manner. The cell death accompanied by this treatment was found to be characterized by chromatin condensation and apoptotic bodies. Azurin treatment was further found to increase the expression of p53 The stabilization of p53 and induction of apoptosis in YD-9 cells by azurin suggests that it has potentially very strong anticancer properties in oral squamous carcinoma.

Cytosolic Ca2+ is an important regulator of tumor cell proliferation and metastasis. Recently, the strategy of blocking receptors and channels specific to certain cancer cell types has emerged as a potentially viable future treatment. Oral squamous cell carcinoma is an aggressive form of cancer with a high metastasis rate but the receptor-mechanisms involved in Ca2+ signaling in these tumors have not yet been elucidated. In our present study, we report that bradykinin induces Ca2+ signaling and its modulation in the human oral squamous carcinoma cell line, HSC-3. Bradykinin was found to increase the cytosolic Ca2+ levels in a concentration-dependent manner. This increase was inhibited by pretreatment with the phospholipase C-β inhibitor, U73122, and also by 2-aminoethoxydiphenyl borate, an inhibitor of the inositol 1,4,5-trisphosphate receptor. Pretreatment with extracellular ATP also inhibited the peak bradykinin-induced Ca2+ rise. In contrast, the ATP-induced rise in cytosolic Ca2+ was not affected by pretreatment with bradykinin. Pretreatment of the cells with either forskolin or phorbol 12-myristate 13-acetate (activators of adenylyl cyclase and protein kinase C, respectively) prior to bradykinin application accelerated the recovery of cytosolic Ca2+ to baseline levels. These data suggest that bradykinin receptors are functional in Ca2+ signaling in HSC-3 cells and may therefore represent a future target in treatment strategies for human oral squamous cell carcinoma.

Tumor cells under hypoxic conditions are often found due to the rapid outgrowth of their vascular supply, and,in order to survive hypoxia, these cells induce numerous signaling factors. Erk is an important kinase in cell survival, and its activity is regulated by Raf kinases through numerous growth factor receptors. The authors investigated Erk activation and Raf/Erk signaling using the hypoxia-mimetic agent, cobalt chloride (CoCl2), in oral squamous cell carcinoma (OSCC) cells. CoCl2 increases Erk phosphorylation in both a dose- and time-dependent manner. In addition, blocking the activation of epidermal growth factor receptor (EGFR) using PD168393 abolished Erk activation in response to CoCl2, suggesting that Erk phosphorylation by CoCl2 is dependent on EGFR.

Anti-proliferation of methanol extract of Curcuma rhizome on oral squamous cell carcinoma (KB) and osteosarcoma (HOS) cells were investigated. In order to elucidate the involvement of telomerase inhibitory activity as a part of anti-proliferative effect of Curcuma rhizome on cancer cells, we measured telomerase activity in Curcuma rhizome extract-treated cancer cells. The concentration inhibited cell proliferation to 50% (IC50)of the methanol extract of Curcuma rhizome against oral squamous cell carcinoma (KB) cells and osteosarcoma (HOS) cells were 21.30 μg/mℓ and 39.3μg/mℓ respectively. The methanol extract of Curcuma rhizome showed inhibitory telomerase inhibitory effect which is required for cancer cell immortality. Therefore, it seems that the anticancer effect of methanol extract of Curcuma rhizome is at least partially due to telomerase inhibitory effect. Five fraction samples were prepared according to its polarity differences and analyzed anti-proliferative effects of each fraction samples on oral squamous cell carcinoma and osteosarcoma cells. Anticancer effect was observed in dichloromethane, and ethylacetate fractions. The highest anticancer effect was found in dichloromethane fraction which had IC50value of 23.3 μg/mℓ and 10.5μg/mℓ against oral squamous cell carcinoma (KB) cells and osteosarcoma (HOS) cells, respectively.

A novel indirubin analog, 5'-nitro-indirubinoxime inhibits cell proliferation and induces apoptosis against various human cancer cells. In this study, we performed the microarray analysis to identify genes differentially expressed in the KB oral squamous carcinoma cells after treated with 5'-nitro-indirubinoxime. Among the 10,800 genes analyzed, 1,701 genes (15.8%) showed statistically different expression level in the 5'-nitro-indirubinoxime treated cells with respect to untreated control cells. Among those, 263 genes (15.5%) were down-regulated and 220 genes (12.9%) were up-regulated more than 2-fold. Functionally related gene clusters include genes associated with signal transduction (18.1%), especially genes related with apoptosis (3.5%) and cell cycle regulation (5.8%). Our application of microarray analysis on 5'-nitro-indirubinoxime treated oral cancer cells allows the identification of candidate genes for providing novel insights into the indirubin mediated antitumor activity.

Concerns remain regarding the biocompatibility and adverse effects of dental casting alloys. The aim of this study was to understand the cytopathogenic effect of metal ions, which might be released from dental alloys, on oral squamous carcinoma(OSC) cells. The cellular morphology, viability, the type of cell death and molecular change in response to metal ion salt solutions including aluminum(Al), cobalt(Co), copper(Cu) and nickel(Ni) were examined. The values for the metal ions with the exception of AI were estimated to be between 400 and 600μM. The cells treated with the metal ions showed apoptotic change with the exception of Al ions. Metal ion-induced apoptosis was further confirmed using flow cytometric analysis. This study showed that the cytotoxicity and the mode of cell death by metal ions clearly depend on the cell type, the type of metal ion and the duration of exposure. The protein level of Rb, a tumor suppressor that affects apoptosis para-doxically, was higher in the cells treated with Co, Cu and Ni. It is believed that apoptosis and cell damage in the OSC cells treated with Co, Cu or Ni can be evoked by the regulation of Rb.