Human Oral Carcinoma Cell Lines Research Articles

BMP‐2 Expression Correlates with Local Failure in Surgically Treated Head and Neck Squamous Cell Carcinoma

Objectives: Preclinical data show that exogenous administration of recombinant human bone morphogenetic protein-2 (rhBMP-2) to human oral carcinoma cell lines increases pathogenicity using a nude mouse model. The objectives of this study are to 1) describe the characteristics of baseline protein expression of BMP-2 in head and neck squamous cell carcinomas (HNSCCs), and 2) determine if BMP-2 expression level correlates with worse oncologic outcomes. Methods: Tissue samples from 149 patients with oral, oropharyngeal, and laryngeal/hypopharyngeal squamous cell carcinomas treated at an academic medical center between 1999 and 2010 were assembled into a tissue microarray. Immunohistochemistry for BMP-2 was performed, and staining was quantified using a standardized scoring system. Specimens were categorized by high or low expression level. Statistical analyses using log-rank, Wilcoxon, and Fisher’s exact test were performed for associations between clinical and pathologic features and patient survival. Results: BMP-2 expression at any level was present in 146 of 149 (97.9%) tissue samples. Tumors with high BMP-2 expression had higher rates of local failure compared with low-expressing tumors (17.3% vs 6.3% P = 0.04). However, there was no significant association for BMP-2 expression level and tumor location, T stage, N stage, regional failure, distant failure, or overall survival. Conclusions: HNSCCs with high levels of BMP-2 protein expression are associated with higher rates of local recurrence. These data may have important implications for using rhBMP-2 in tissue engineering reconstructive approaches in the setting of cancer-related defects. Further, the consistent expression of BMP-2 suggests this pathway may be a novel therapeutic target.

Cucurbitacin E as Inducer of Cell Death and Apoptosis in Human Oral Squamous Cell Carcinoma Cell Line SAS

Human oral squamous cell carcinoma (OSCC) is a common form of malignant cancer, for which radiotherapy or chemotherapy are the main treatment methods. Cucurbitacin E (CuE) is a natural compound previously shown to be an antifeedant as well as a potent chemopreventive agent against several types of cancer. The present study investigates anti-proliferation (using MTT assay, CuE demonstrated cytotoxic activity against SAS cell with IC50 values at 3.69 μM) and induced apoptosis of human oral squamous cell carcinoma SAS cells after 24 h treatment with CuE. Mitochondrial membrane potential (MMP) and caspase activity were studied and our results indicate that CuE inhibits cell proliferation as well as the activation of apoptois in SAS cells. Both effects increased in proportion to the dosage of CuE and apoptosis was induced via mitochondria- and caspase-dependent pathways. CuE can induce cell death by a mechanism that is not dependent on apoptosis induction, and thus represents a promising anticancer agent for prevention and treatment of OSCC.

Spindle and kinetochore associated complex subunit 1 regulates the proliferation of oral adenosquamous carcinoma CAL-27 cells in vitro

BackgroundThe prognosis of oral squamous cell carcinoma is very poor due to local recurrence and metastasis. This study explores the molecular events involved in oral carcinoma with the goal of developing novel therapeutic strategies. The mitotic spindle is a complex mechanical apparatus required for the accurate segregation of sister chromosomes during mitosis. Spindle and kinetochore associated complex subunit 1 (SKA1) is a microtubule-binding subcomplex of the outer kinetochore that is essential for proper chromosome segregation. In recent years, much attention has been focused on determining how SKA proteins interact with each other, as well as their biological role in cancer cells. However, the precise role of SKA1 in oral carcinoma remains unknown.MethodsIn order to investigate the role of SKA1 in oral cancer, we employed lentivirus-mediated shRNA to silence SKA1 expression in the CAL-27 human oral adenosquamous carcinoma cell line.ResultsDepletion of SKA1 in CAL-27 cells significantly decreased cell proliferation, as determined by MTT and colony formation assays. These results strongly demonstrate that reduced SKA1 protein levels may cause inhibition of tumor formation. The shRNA-mediated depletion of SKA1 also led to G2/M phase cell cycle arrest and apoptosis.ConclusionThis is the first report to show that SKA1 plays an important role in the progression of oral adenosqamous carcinoma. Thus, silencing of SKA1 by RNAi might be a potential therapy for this disease.

Metabolomic profiling of sodium fluoride-induced cytotoxicity in an oral squamous cell carcinoma cell line

Sodium fluoride (NaF) is used in dentistry as a preventive agent for dental caries because of its ability to remineralize the tooth surface and its antibacterial effect. Although one of its target molecules in bacteria is enolase, its site of action in human cells has not been identified. The aim of this study was to identify target metabolites that are coupled to NaF-induced cytotoxicity in the HSC-2 human oral squamous cell carcinoma cell line. Cell viability, membrane integrity and apoptosis induction were analyzed by MTT assay, trypan blue exclusion and caspase-3 activation, respectively. Cells were treated with a minimal cytotoxic concentration of NaF for various times and subjected to comprehensive metabolomics analysis using capillary electrophoresis-mass spectrometry. In the early stages, inhibition of the enolase reaction in glycolysis pathway was observed. This was coupled with rapid inhibition of the progression of TCA cycle. In the later stages, gradual increases in the AMP/ATP ratio (a putative marker of apoptosis) and oxidized products (e.g. GSSH, and methionine sulfoxide), and marginal changes in polyamine levels (putative marker of necrosis) were observed. This manuscript provides the new insight into the global impact of NaF on metabolic pathways in human oral squamous cell carcinoma cells.

Phthalocyanines functionalized with 2-methyl-5-nitro-1H-imidazolylethoxy and 1,4,7-trioxanonyl moieties and the effect of metronidazole substitution on photocytotoxicity

Four novel magnesium(II) and zinc(II) phthalocyanines bearing 1,4,7-trioxanonyl, polyether and/or (2-methyl-5-nitro-1H-imidazol-1-yl)ethoxy, heterocyclic substituents at their non-peripheral positions were synthesized and assessed in terms of physicochemical and biological properties. Magnesium phthalocyanine derivatives bearing polyether substituents (Pc-1), a mixed system of polyether and heterocyclic substituents (Pc-3), and four heterocyclic substituents (Pc-4), respectively, were synthesized following the Linstead macrocyclization reaction procedure. Zinc phthalocyanine (Pc-2) bearing polyether substituents at non-peripheral positions was synthesized following the procedure in n-pentanol with the zinc acetate, and DBU. Novel phthalocyanines were purified by flash column chromatography and characterized using NMR, MS, UV–Vis and HPLC. Moreover, two precursors in macrocyclization reaction phthalonitriles were characterized using X-ray. Photophysical properties of the novel macrocycles were evaluated, including UV–Vis spectra analysis and aggregation study. All macrocycles subjected to singlet oxygen generation and the oxidation rate constant measurements exhibited lower quantum yields of singlet oxygen generation in DMSO than in DMF. In addition, the Pc-2 molecule was found to be the most efficient singlet oxygen generator from the group of macrocycles studied. The photocytotoxicity evaluated on the human oral squamous cell carcinoma cell line, HSC-3, for Pc-3 was significantly higher than that for Pc-1, Pc-2, and Pc-4. Interestingly, Pc-3 was found to be the most active macrocycle in vitro although its ability to generate singlet oxygen was significantly lower than those of Pc-1 and Pc-2. However, attempts to encapsulate phthalocyanines Pc-1–Pc-3 in liposomal membranes were unsuccessful. The phthalocyanine–nitroimidazole conjugate, Pc-4 was encapsulated in phosphatidylglycerol:phosphatidylcholine unilamellar liposomes and subjected to photocytotoxicity study.

Anti-Inflammatory Components from the Root of Solanum erianthum

Two new norsesquiterpenoids, solanerianones A and B (1–2), together with nine known compounds, including four sesquiterpenoids, (−)-solavetivone (3), (+)-anhydro-β-rotunol (4), solafuranone (5), lycifuranone A (6); one alkaloid, N-trans-feruloyltyramine (7); one fatty acid, palmitic acid (8); one phenylalkanoid, acetovanillone (9), and two steroids, β-sitosterol (10) and stigmasterol (11) were isolated from the n-hexane-soluble part of the roots of Solanum erianthum. Their structures were elucidated on the basis of physical and spectroscopic data analyses. The anti-inflammatory activity of these isolates was monitored by nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW264.7 cells. The cytotoxicity towards human lung squamous carcinoma (CH27), human hepatocellular carcinoma (Hep 3B), human oral squamous carcinoma (HSC-3) and human melanoma (M21) cell lines was also screened by using an MTT assay. Of the compounds tested, 3 exhibited the strongest NO inhibition with the average maximum inhibition (Emax) at 100 μM and median inhibitory concentration (IC50) values of 98.23% ± 0.08% and 65.54 ± 0.18 μM, respectively. None of compounds (1–9) was found to possess cytotoxic activity against human cancer cell lines at concentrations up to 30 μM.

RUNX3 confers sensitivity to pheophorbide a-photodynamic therapy in human oral squamous cell carcinoma cell lines

Photodynamic therapy (PDT) with photosensitizer is one of the promising modalities for cancer treatment. For clinical use of PDT, screening process should be preceded to enhance sensitivity to PDT. Thus, we investigated a molecular biomarker to determine the sensitivity to pheophorbide a (Pa)-PDT in immortalized human oral keratinocytes (IHOK) and oral squamous cell carcinoma (OSCC) cell lines. Two IHOK and several OSCC cell lines were used. After Pa-PDT, cell viability was reduced by more than 50%, and reactive oxygen species were generated in IHOK and OSCC cell lines. Additionally, apoptosis occurred in PDT-treated cells. IHOK(S) and IHOK(P), the two IHOK cell lines derived from the same source, showed a difference in cytotoxicity after Pa-PDT. To explain this difference in cytotoxicity, we looked at the expression of Wnt signaling-related genes in these two cell lines, for the morphology of IHOK(S) which was spindle like and elongated and distinct from IHOK(P) and the parent cell. Among the relevant genes, runt-related transcription factor 3 (RUNX3), an apoptosis-related gene, was selected as a potential marker that confers sensitivity to PDT. We found that the cytotoxicity by Pa-PDT was proportional to RUNX3 expression in OSCC cell lines. Additionally, knockdown of RUNX3 expression reduced cytotoxicity by Pa-PDT, suggesting that RUNX3 might be a biomarker to determine sensitivity to Pa-PDT. This was the first study to find a new target molecule that enhances Pa-PDT effects in IHOK and OSCC cell lines. Hence, the development of a PDT-dependent biomarker could provide a novel approach to improve the effects of PDT on oral precancerous and cancerous lesions.

The radiosensitization effect of mTOR inhibitior in human tongue squamous cell carcinoma.

e13585 Background: mTOR plays a critical role in malignant phenotype in many tumors. Everolimus [RAD001 (40-O-(2-hydroxyethyl)-rapamycin)] is a rapamycin rapalog that is being developed as an antitumor agent and is approved for various cancers. Recently, RAD001 has also been reported to increase the radiosensitization following for amplifying the autophagic pathway; however, it could promote an alternative mechanism that leads to apoptosis. In HNSCC, radiation therapy is a common form of cancer treatment, but locoregional recurrence and/or distant metastasis is the most cause of failure after RT and it results in HNSCC significant morbidity. Evidence from previous studies showed that RAD001 enhanced the cytotoxic effects of radiation in HNSCC cell lines. The molecular mechanism of radiosensitization by RAD001 in HNSCC has not cleared.Our aim is to evaluate the role of molecular mechanism of RAD001-mediated radiosensitization in HNSCC. Methods: Radiosensitivity effects of RAD001 were assays on human oral squamous cell carcinoma cell lines (SCC4 and DuFa). RAD001 (30 and 300 nM)and radiation (0~8 Gy) alone and in combination were evaluated for antitumor activity in the clonogenic assay. Next, we also evaluated the RAD001 on radiation-induced signal transduction by western blot analysis. Results: Here, we show that 300nM RAD001 plus 6 Gy cohort with significant HNSCC cell line growth suppression compared to 6 Gy alone (p=0.004) or 30n MRAD001 plus 6 Gy (p=0.008). RAD001 treatment effectively reduces mTOR downstream effector p-S6 protein compared with the vehicle or irradiated alone. RAD001 + 6 Gy significantly increases p53 and PARP cleavage, which facilitates apoptosis. Unexpectedly, autophagy pathway, such as beclin 1 and LC3II were not affected by RAD001. Addiationlly, we discover that Akt phosphorylation (Ser473) is up-regulated after RAD001/and irradiation of HNSCC cells. Conclusions: These findings suggest radiosensitization by the RAD001 involves the induction of apoptosis in HNSCC. Notwithstanding, Akt signaling is increased under RAD001 and it could attenuate anticancer efficacy instead, contribute to the development of resistance.

Involvement of cholesterol depletion from lipid rafts in apoptosis induced by methyl-β-cyclodextrin

Methyl-β-cyclodextrin (M-β-CyD), which is widely used as a lipid rafts disrupting agent, is known to induce cytotoxicity at high concentration. In the present study, we investigated the potential of M-β-CyD as an antitumor drug. M-β-CyD markedly caused apoptotic cell-death in KB cells, a human oral squamous carcinoma cell line, Ihara cells, a highly pigmented human melanoma cell line, and M213 cells, a human cholangiocarcinoma cell line, through cholesterol depletion in cell membranes. The DNA content and mitochondrial transmembrane potential in KB cells were significantly decreased after treatment with M-β-CyD. Additionally, M-β-CyD elevated the caspase-3/7 activity in KB cells. Meanwhile, M-β-CyD did not induce the formation of autophagic vacuoles in KB cells. M-β-CyD drastically inhibited the tumor growth after intratumoral injection to Colon-26 cells-bearing mice. These results strongly suggest that M-β-CyD induced apoptosis in tumor cells and had the potential a novel antitumor agent and/or its lead compound.

Gene Delivery with Active Targeting to Ovarian Cancer Cells Mediated by Folate Receptor α

Folate receptor alpha (FRalpha) is overexpressed on ovarian cancer cells and is a promising molecular target for ovarian cancer gene therapy, but there was still no related report. In this study, folate modified cationic liposomes (F-PEG-CLPs) for ovarian cancer gene delivery were developed for the first time. Folate-poly(ethylene glycol)-succinate-cholesterol (F-PEG-suc-Chol) was firstly synthesized and then used to prepare folate-targeted cationic liposomes/plasmid DNA complexes (F-targeted lipoplexes). F-targeted lipoplexes were prepared by post-insertion method, and displayed membrane structure by transmission electron microscopy observation with the diameter of 193 nm-200 nm and the zeta potential of 35 mV-38 mV. DNase degradation experiments showed that plasmid DNA could be effectively shielded by F-targeted lipoplexes in vitro. F-targeted lipoplexes could transfer gene into human ovarian carcinoma cell line SKOV-3, and 0.1% F-PEG-CLPs composed by DOTAP/Chol/mPEG-Chol/F-PEG-suc-Chol (50:45:5:0.1, molar ratio) had the highest transfection efficiency. The transfection activity of F-targeted lipoplexes could be competitively inhibited by free folic acid, demonstrating that folate-FRalpha interaction caused high transfection efficiency of F-targeted lipoplexes. The uptake mechanism of F-targeted lipoplexes was further validated on human oral carcinoma cell line KB and human liver carcinoma cell line HepG2. The concentration-dependent and time-dependent cytotoxicity of targeted material F-PEG-suc-Chol was observed by MTT assay on SKOV-3 cell and its application would not increase the cytotoxicity of F-targeted lipoplexes in SKOV-3 cells. All the data indicated that F-PEG-CLPs would be a promising gene vector targeting for ovarian cancer therapy.

Abstract 3880: Exploring the role of up-regulated genes in highly metastatic oral cancer subline using spontaneous metastatic mouse model.

Abstract Metastasis is one of the critical factors contributing to poorer prognosis and QOL in cancer patients. Although this mechanism has been gradually revealed, there are few genes found as useful diagnostic markers or molecular targets for clinical application so far. In this study, we attempted to establish in vitro/in vivo metastatic models using a human oral squamous cell carcinoma cell lines (HOC313). We first carried out in vivo selection of high-metastatic tumor cells by means of sequential subcutaneous (s.c.) implantation (1×107 cells) of this cell line into SCID mice, resulting in the establishment of a highly metastatic subline which metastasized to axillary lymph nodes and lung. Moreover, we developed the imaging system using parent cells and highly metastatic cells. Then, to explore metastasis-related genes and signaling pathways, we performed integrative analyses using array CGH, cDNA microarray and the systems biological approach based on their data sets. Then we identified copy number aberrations (CNAs) of chromosome 19 and differentially expressed genes between parent cells and high-metastatic cells. Up regulated genes in high-metastatic cells are related with cell growth, migration, invasion and metastatic ability. Among these, one gene was closely associated with migration, invasion and metastasis. Moreover, when knocking down of this gene, we observed morphological change from mesenchymal phenotype to epithelial phenotype. Further analyses of these genes may ultimately lead to the development of novel modalities of diagnosis and therapy for cancer metastasis. Citation Format: Tomoki Muramatsu, Ken-ichi Kozaki, Seiya Imoto, Rui Yamaguchi, Satoru Miyano, Johji Inazawa. Exploring the role of up-regulated genes in highly metastatic oral cancer subline using spontaneous metastatic mouse model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3880. doi:10.1158/1538-7445.AM2013-3880

Characterization and in vitro cytotoxicity of doxorubicin-loaded γ-polyglutamic acid-chitosan composite nanoparticles

In this study, γ-polyglutamic acid (γ-PGA) and chitosan (CS) nanoparticles were characterized as a carrier for the anti-cancer drug doxorubicin (DOX). Using ionic complexation between the positively charged DOX and the negatively charged polyelectrolyte γ-PGA, DOX:γ-PGA complexes were produced with an efficiency of approximately 99%. SEM micrographs demonstrated that the complexation of γ-PGA and DOX alone does not lead to the formation of nanoparticles and that the addition of a third component, chitosan, is required. Drug-loaded DOX:γ-PGA:CS nanoparticles were produced with particle sizes ranging from ~150 to ~630nm. The stability of the DOX:γ-PGA:CS nanoparticles was examined by suspending the nanoparticles in different kinds of aqueous media. For the first time, in vitro studies with DOX-loaded nanoparticles demonstrated the cytotoxicity of the nanoparticles against a human oral squamous cell carcinoma cell line (HN-5a). Non-drug-loaded γ-PGA:CS nanoparticles did not display cytotoxic effects. It was shown that the encapsulated or surface-bound DOX did not lose its bioactivity and the prepared drug-loaded particles exhibited a considerable anti-proliferative activity against the human cancer cell line.

ChemInform Abstract: Novel Cytotoxic Phenanthrenequinone from Odontioda Marie Noel “Velano”.

AbstractA new phenanthrenequinone (I) is isolated together with known ephemeranthoquinone B.

Photophysical and photobiological properties of a sulfonated chlorin photosensitiser TPCS2a for photochemical internalisation (PCI)

This study investigated the photophysical and photobiological properties of a new amphiphilic chlorin photosensitiser, disulfonated tetraphenylchlorin (TPCS(2a)), for photochemical internalisation (PCI). The absorption and fluorescence spectra of TPCS(2a) were examined in a range of solvents together with fluorescence lifetime measurements. The fluorescence lifetime of TPCS(2a) was found to be 8.5 ns in methanol, whereas non-exponential decays were observed in distilled water due to sensitiser dimerisation. The singlet oxygen quantum yield of TPCS(2a) was determined as 0.62 in deuterated methanol by direct observation of singlet oxygen phosphorescence. In a human oral squamous carcinoma (HN5) cell line, intracellular co-localisation of TPCS(2a) and Alexa488-labelled saporin, a macromolecular toxin, was observed corresponding predominantly to a lysosomal distribution. Intracellular fluorescence redistribution of TPCS(2a) and Alexa488-saporin was observed after 405 nm irradiation. Using two-photon confocal microscopy at 840 nm, and fluorescence lifetime imaging (FLIM), the lifetime was measured as 6 ns in HN5 cells. PCI using TPCS(2a) was shown to be very effective, and a synergistic increase in saporin toxicity was achieved in HN5 cells where viability was significantly reduced after light exposure compared to saporin (25 nM) treatment alone. The results demonstrate the favourable photophysical and photobiological properties of TPCS(2a) for PCI, which induces the relocalisation of a macromolecular anti-cancer toxin inside cells and significantly enhances cell death.

Efficient nonviral gene therapy with FasL and Del1 fragments in mice

The expression of FasL in cancer cells is currently being explored as a potential cancer therapy. Because high levels of FasL are necessary for effective treatment, current methods typically rely on the use of highly efficient viral vectors. However, because viral vector-based gene therapy is associated with certain risks, the development of effective nonviral routes for gene delivery would be useful. The present study aimed to improve FasL gene therapy with a nonviral vector by taking advantage of the E3 and C1 domains of Del1 protein, which induces apoptosis and localizes to the extracellular matrix. Mouse explanted tumors derived from a human oral squamous cell carcinoma cell line, SCCKN, were treated with plasmids encoding FasL (pFasL), E3C1 (pE3C1), and a fusion of FasL and E3C1 (pFasL-E3C1). The plasmids were injected locally every 7 days along with a transfection reagent, Jet-PEI (PolyPlus-transfection, San Marcos, CA, USA). All mice treated with a negative control plasmid or pFasL died within 49 days. By contrast, 83% of mice treated with pFasL-E3C1 survived longer than 49 days. Histochemical studies revealed that the fusion protein is localized to the stroma and induces apoptosis in stromal cells and adjacent parenchymal cells. The results obtained in the present study suggest that the protein deposition-based approach described, which makes use of the E3 and C1 domains of Del1, could comprise a novel method for cancer gene therapy with nonviral vectors.

Angucyclines from an insect-derived actinobacterium Amycolatopsis sp. HCa1 and their cytotoxic activity

One new angucyclinone derivative, amycomycin A (1), and one new angucycline, amycomycin B (2), along with 5 known compounds (3–7), were isolated from an actinobacterium Amycolatopsis sp. HCa1 associated with the grasshopper, Oxya chinensis. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR spectra. Compounds 1–7 were tested in vitro for their cytotoxic effects on five cell lines including human gastric adenocarcinoma cell line (BGC823), human hepatocarcinoma cell line (HepG2), human melanoma cell line (A375), human oral squamous carcinoma cell line (KB), and ghost cell line (Ghost-R5X4). Cell viability assays showed that compound 7 was active in four cell lines with IC50 values less than 18.0μM except in KB showing no activity up to 100μM.

Development of Chitosan Oligosaccharide-Modified Gold Nanorods for in Vivo Targeted Delivery and Noninvasive Imaging by NIR Irradiation

In the present study, we demonstrate the synthesis and applications of multifunctional gold nanorod-based probes for specific targeting and noninvasive imaging based on localized heating generated by gold nanorods after NIR irradiation. The structural design of the probe consists of MUA (11-mercaptoundecanoic acid)-capped gold nanorods covalently linked with low-molecular-weight chitosan oligosaccharide (M(w) ~5000) via carbodiimide (EDC) coupling agent. This surface modification is performed for complete replacement of toxic CTAB (hexadecyltrimethyl-ammonium chloride) and acid-responsive delivery of gold nanorods in acidic environment as known to be present at tumor surrounding areas. The resulting chitosan oligosaccharide-modified gold nanorods (CO-GNRs) were further conjugated with tumor targeting monoclonal antibody against EGFR (epidermal growth factor receptor) to provide localized targeting functionality owing to the overexpression of EGFR in human oral adenosquamous carcinoma cell line CAL 27. Initial in vitro and in vivo toxicity assessments indicated that CO-GNRs did not induce any significant toxicity and are thus suitable for biological applications. Furthermore, selective targeting and accumulation of CO-GNRs were observed in vitro via two-photon luminescence imaging studies in CAL 27, which was also observed through in vivo targeting studies performed via NIR (near-infrared) laser irradiation in CAL 27 xenografts of BALB/c nude mice. Hence, the CO-GNRs that we have developed are biocompatible and nontoxic and can be a potential candidate for in vivo targeted delivery, noninvasive imaging based on localized hyperthermia, and photothermal-related therapies.

Radiation protective effect of Hypoxia-inducible factor-1 (HIF-1 ) on human oral squamous cell carcinoma cell lines

We examined the effects of 5-Gy radiation on the expression of hypoxia-inducible factor-1α (HIF-1α) and the radiosensitivity of five human oral squamous cell carcinoma (OSCC) cell lines (SAS, Ca9-22, TT, BSC-OF and IS-FOM). In all of the cell lines, HIF-1α was expressed in mRNA, and radiation had no influence on gene transcription. The number of apoptotic cells increased 72 h after irradiation in cell lines SAS, Ca9-22 and TT cells, indicating low transcriptional levels of HIF-1α, and the levels of non-cleaved caspase-3, an executioner of apoptosis, and non-cleaved poly (adenosine diphosphate-ribose) polymerase (PARP), a marker of DNA damage early in apoptosis, decreased simultaneously. Conversely, radiation failed to induce apoptosis or to decrease expression of non-cleaved caspase-3 and PARP in cell lines BSC-OF and IS-FOM cells that expressed high levels of HIF-1α. BSC-OF and IS-FOM cells exhibited high migratory capacity. When CoCl(2) was present in the medium, HIF-1α expression increased along with the survival of Ca9-22 cells after radiation exposure. These results suggest that OSCC cells expressing high levels of HIF-1α are resistant to radiation. HIF-1α can be used to control the short-term radiosensitivity of cells.

The potential anticancer activity of extracts derived from the roots of Scutellaria baicalensis on human oral squamous cell carcinoma cells

Various herb products derived from plants have potent biological effects including anticancer activity. In the present study, the antitumor activity of a herbal product derived from the Scutellaria baicalensis (S. baicalensis) was examined, using in vitro assays in a human oral squamous cell carcinoma (OSCC) cell line. Results showed that S. baicalensis root extract at the concentration of 100 μg/ml inhibited monolayer- and anchorage-independent growth in human OSCC cell lines, while not affecting the adhering abilities of cells. This suggested that it did not alter the expression of any of the adhesion receptors that mediate cell-extracellular matrix (ECM) interactions. The S. baicalensis root extract demonstrated potent cytostatic and apoptotic effects due to the downregulation of the cyclin-dependent kinase 4 expression and its partner cyclin D1, resulting in G1 arrest and poly (ADP-ribose) polymerase (PARP) cleavage. Additionally, the S. baicalensis root extract was found to have blocked vascular endothelial growth factor (VEGF)-induced migration and tube formation in human endothelial cells. Taken together, these results demonstrate that as a herbal product, the S. baicalensis root extract is a potential inhibitor of tumori- and angiogenesis and may be valuable in the development of pharmaceutical medications for the treatment of oral squamous cell carcinoma.

Tumor necrosis factor-α enhanced fusions between oral squamous cell carcinoma cells and endothelial cells via VCAM-1/VLA-4 pathway

Fusion between cancer cells and host cells, including endothelial cells, may strongly modulate the biological behavior of tumors. However, no one is sure about the driving factors and underlying mechanism involved in such fusion. We hypothesized in this study that inflammation, one of the main characteristics in tumor microenvironment, serves as a prominent catalyst for fusion events. Our results showed that oral cancer cells can fuse spontaneously with endothelial cells in co-culture and inflammatory cytokine tumor necrosis factor-α (TNF-α) increased fusion of human umbilical vein endothelium cells and oral cancer cells by up to 3-fold in vitro. Additionally, human oral squamous cell carcinoma cell lines and 35 out of 50 (70%) oral squamous carcinoma specimens express VLA-4, an integrin, previously implicated in fusions between human peripheral blood CD34-positive cells and murine cardiomyocytes. Expression of VCAM-1, a ligand for VLA-4, was evident on vascular endothelium of oral squamous cell carcinoma. Moreover, immunocytochemistry and flow cytometry analysis revealed that expression of VCAM-1 increased obviously in TNF-α-stimulated endothelial cells. Anti-VLA-4 or anti-VCAM-1 treatment can decrease significantly cancer–endothelial adhesion and block such fusion. Collectively, our results suggested that TNF-α could enhance cancer–endothelial cell adhesion and fusion through VCAM-1/VLA-4 pathway. This study provides insights into regulatory mechanism of cancer–endothelial cell fusion, and has important implications for the development of novel therapeutic strategies for prevention of metastasis.