Epithelial-mesenchymal Transition In Head And Neck Squamous Cell Carcinoma Research Articles

Impact of Hypoxia and the Levels of Transcription Factor HIF-1α and JMJD1A on Epithelial-Mesenchymal Transition in Head and Neck Squamous Cell Carcinoma Cell Lines.

This study aimed to assess the impact of hypoxia on epithelial-mesenchymal transition (EMT) in head and neck squamous cell carcinoma (HNSCC), focusing on the involvement of transcription factors hypoxia inducible factor 1 (HIF-1α) and Jumonji Domain-Containing Protein 1A (JMJD1A). FaDu and Cal33 cell lines were subjected to hypoxic and normoxic conditions. Cell proliferation was quantified electronically, while PCR and western blot analyses were used to measure mRNA and protein levels of HIF-1α, JMJD1A, and EMT markers. EMT was further characterized through immunofluorescence, migration, and invasion assays. Hypoxic conditions significantly reduced cell proliferation after 48 hours in both cell lines. HIF-1α mRNA levels increased initially during short-term hypoxia but declined thereafter, while JMJD1A mRNA levels showed a sustained increase with prolonged hypoxia. Western blot analysis revealed contrasting trends in protein levels. EMT marker expression varied markedly over time at both the mRNA and protein levels, suggesting EMT induction in hypoxia within 24 hours. Immunofluorescence, migration, and invasion assays supported these findings. The study provides evidence of hypoxia-induced EMT in HNSCC, although conflicting results suggest a complex interplay among molecular regulators involved in this process.

P4HA2 contributes to head and neck squamous cell carcinoma progression and EMT through PI3K/AKT signaling pathway

Head and neck squamous cell carcinoma (HNSCC) can be defined as a deadly illness with a dismal prognosis in advanced stages. Therefore, we seek to examine P4HA2 expression and effect in HNSCC, along with the underlying mechanisms. This study utilized integrated bioinformatics analyses to evaluate the P4HA2 expression pattern, prognostic implication, and probable function in HNSCC. The study conducted various in vitro experiments, including colony formation, CCK-8, flow cytometry, wound healing, and transwell assays, on the human HNSCC cell line CAL-27 to examine the involvement of P4HA2 in HNSCC progression. Moreover, western blotting was used to investigate epithelial-mesenchymal transition (EMT) markers and PI3K/AKT pathway markers to elucidate the underlying mechanisms. P4HA2 expression was significantly enhanced in HNSCC, and its overexpression was correlated to tumor aggressiveness and a poor prognosis in patients. Based on in vitro experiments, the overexpressed P4HA2 enhanced cell proliferation, migration, invasion, as well as EMT while reducing apoptosis, whereas P4HA2 silencing exhibited the reverse effect. P4HA2 overexpression enhanced PI3K/AKT phosphorylation in HNSCC cells. Moreover, LY294002 was observed to counteract the effects of upregulated P4HA2 on proliferation, migration, invasion, and EMT in HNSCC. Collectively, we indicated that P4HA2 promoted HNSCC progression and EMT via PI3K/AKT signaling pathway.

Increased FGL1 Expression Predicts Poor Prognosis and Promotes EMT in Head and Neck Squamous Cell Carcinoma.

Fibrinogen-like protein 1 (FGL1) is a proliferation- and metabolism-related factor secreted by the liver that is aberrantly expressed and functionally abnormal in human malignancies. However, the role of FGL1 in head and neck squamous cell carcinoma (HNSCC) remains unknown. We analysed FGL1 expression in HNSCC and its impact on patient survival using the TCGA database. The role of FGL1 in HNSCC cells was investigated by Cell Counting Kit-8, colony formation, and Transwell assays. In addition, we conducted in vivo experiments to assess the effect of FGL1 knockdown on tumour growth. We found that FGL1 was highly expressed in HNSCC and correlated with a poor prognosis. Downregulation of FGL1 expression inhibited the proliferation and invasion of HNSCC cells. Furthermore, mechanistic analysis revealed that FGL1 induced an epithelial-mesenchymal transition (EMT) phenotype and, thus, the malignant progression of HNSCC cells. Finally, xenograft models showed that FGL1 knockdown significantly inhibited EMT in HNSCC in vivo. Our study revealed that FGL1, an oncogene, promotes the malignant progression of HNSCC, providing new perspective on and potential therapeutic target for the treatment of HNSCC.

Deubiquitinase YOD1 suppresses tumor progression by stabilizing E3 ligase TRIM33 in head and neck squamous cell carcinoma

Ubiquitination is a reversible process that not only controls protein synthesis and degradation, but also is essential for protein transport, localization and biological activity. Deubiquitinating enzyme (DUB) dysfunction leads to various diseases, including cancer. In this study, we aimed to explore the functions and mechanisms of crucial DUBs in head and neck squamous cell carcinoma (HNSCC). Based on bioinformatic analysis and immunohistochemistry detection, YOD1 was identified to be significantly downregulated in HNSCC specimens compared with adjacent normal tissues. Further analysis revealed that reduced YOD1 expression was associated with the malignant progression of HNSCC and indicated poor prognosis. The results of the in vitro and in vivo experiments verified that YOD1 depletion significantly promoted growth, invasion, and epithelial-mesenchymal transition in HNSCC. Mechanistically, YOD1 inhibited the activation of the ERK/β-catenin pathway by suppressing the ubiquitination and degradation of TRIM33, leading to the constriction of HNSCC progression. Overall, our findings reveal the molecular mechanism underlying the role of YOD1 in tumor progression and provide a novel potential therapeutic target for HNSCC treatment.

FAM83A promotes proliferation and metastasis via Wnt/\u03b2-catenin signaling in head neck squamous cell carcinoma

This research aimed to investigate the expression and function of FAM83A in the proliferation and metastasis in head and neck squamous cell carcinoma (HNSCC). FAM83A mRNA and protein expressions in HNSCC were detected in primary HNSCC samples and cell lines. The associations between FAM83A expression and clinicopathologic variables were evaluated through tissue microarrays. Besides, FAM83A knockdown and overexpression cell lines were constructed to assess cell growth and metastasis in vitro and the relationship between FAM83A and epithelial-mesenchymal transition (EMT). Furthermore, two models of xenograft tumors in nude mice were used to assess the tumorigenicity and metastasis ability of FAM83A in vivo. In the present study, overexpression of FAM83A in HNSCC samples was significantly associated with tumor size, lymph node status and clinical tumor stages. Mechanically, FAM83A could promote HNSCC cell growth and metastasis by inducing EMT via activating Wnt/β-catenin signaling pathway. Rescue experiment demonstrated the inhibition of β-catenin could counteract the function of FAM83A. Also, the FAM83A knockdown could suppress tumor growth and distant metastasis in the xenograft animal models of HNSCC. In conclusion, this study identifies FAM83A as an oncogene of HNSCC. This study provides new insights into the molecular pathways that contribute to EMT in HNSCC. We revealed a previously unknown FAM83A-Wnt–β-catenin signaling axis involved in the EMT of HNSCC. There may be a potential bi-directional signaling loop between FAM83A and Wnt/β-catenin signaling pathway in HNSCC.

Regulation of FN1 degradation by the p62/SQSTM1-dependent autophagy\u2013lysosome pathway in HNSCC

Epithelial–mesenchymal transition (EMT) is involved in both physiological and pathological processes. EMT plays an essential role in the invasion, migration and metastasis of tumours. Autophagy has been shown to regulate EMT in a variety of cancers but not in head and neck squamous cell carcinoma (HNSCC). Herein, we investigated whether autophagy also regulates EMT in HNSCC. Analyses of clinical data from three public databases revealed that higher expression of fibronectin-1 (FN1) correlated with poorer prognosis and higher tumour pathological grade in HNSCC. Data from SCC-25 cells demonstrated that rapamycin and Earle’s balanced salt solution (EBSS) promoted autophagy, leading to increased FN1 degradation, while 3-methyladenine (3-MA), bafilomycin A1 (Baf A1) and chloroquine (CQ) inhibited autophagy, leading to decreased FN1 degradation. On the other hand, autophagic flux was blocked in BECN1 mutant HNSCC Cal-27 cells, and rapamycin did not promote autophagy in Cal-27 cells; also in addition, FN1 degradation was inhibited. Further, we identified FN1 degradation through the lysosome-dependent degradation pathway using the proteasome inhibitor MG132. Data from immunoprecipitation assays also showed that p62/SQSTM1 participated as an autophagy adapter in the autophagy–lysosome pathway of FN1 degradation. Finally, data from immunoprecipitation assays demonstrated that the interaction between p62 and FN1 was abolished in p62 mutant MCF-7 and A2780 cell lines. These results indicate that autophagy significantly promotes the degradation of FN1. Collectively, our findings clearly suggest that FN1, as a marker of EMT, has adverse effects on HNSCC and elucidate the autophagy–lysosome degradation mechanism of FN1.

Epithelial-Mesenchymal Transition in Head and Neck Cancer

Metastasis is one of the most important factors in the prognosis and choice of treatment strategy of patients with head and neck squamous cell carcinoma (HNSCC). In order for dissemination to take effect, tumor cells must segregate themselves from their primary tumor site and migrate into the blood or lymphatic vessels. To detach from the primary tumor, cells have to disrupt cell-cell adhesion, remodel of the cytoskeleton, change in cell-matrix adhesion and finally return to their original condition. This temporary and reversible process is known as the epithelial-mesenchymal transition (EMT). EMT is a dynamic cellular process in which epithelial cells acquire mesenchymal features and suggested to play an important role during cancer invasion and metastasis. With the recent explosion of knowledge on EMT in carcinogenesis, EMT has become an interesting target for anticancer therapy. This review article first highlights at the biochemical changes that take place around the cell membrane called cadherin switching during EMT and looks at the current literature on EMT in HNSCC. Understanding the mechanism of EMT will provide insight to the metastasis of HNSCC and may lead to the development of novel anti-cancer therapeutics.

Targeting of EZH2 inhibits epithelial‑mesenchymal transition in head and neck squamous cell carcinoma via regulating the STAT3/VEGFR2 axis.

Tumor metastasis regulated by epithelial‑mesenchymal transition (EMT) plays a significant role in the development of human cancers, whereas the molecular mechanisms of this process in head and neck squamous cell carcinoma (HNSCC) remain elusive. In this study, we found that inhibition of enhancer of zeste homolog2 (EZH2) resulted in suppressed EMT in HNSCC invitro and invivo. We reported that signal transducer and activator of transcription factor3 (STAT3)/vascular endothelial growth factor receptor2 (VEGFR2) axis served as the downstream signaling of EZH2 and mediated EMT in HNSCC. EZH2 inhibition downregulated the expression of key molecules of the STAT3/VEGFR2 axis and EMT‑related markers, while the expression of E‑cadherin was upregulated in HNSCC cells. Targeting the EZH2/STAT3/VEGFR2 axis significantly reduced motility of HNSCC cells. Furthermore, EZH2 knockdown reduced the growth of xenograft HNSCC tumors via inhibiting the EZH2/STAT3/VEGFR2 axis. In conclusion, we proposed that EZH2 regulates EMT and tumor invasion and metastasis in HNSCC by governing the STAT3/VEGFR2 axis. These findings provide a rationale for developing novel strategies to treat invasive and metastatic HNSCC via targeting the EZH2/STAT3/VEGFR2 pathway.

Metformin sensitizes hypoxia-induced gefitinib treatment resistance of HNSCC via cell cycle regulation and EMT reversal.

ObjectivesThe objectives of this study were to explore the mechanisms of metformin sensitization to hypoxia-induced gefitinib treatment in resistant head and neck squamous cell carcinoma (HNSCC) and evaluate the effects of this combined treatment strategy.MethodsThe effects of gefitinib treatment on HNSCC were measured under normoxic and hypoxic conditions. The relationship between hypoxia and cell cycle and epithelial–mesenchymal transition (EMT) in tumor cells were analyzed. Palbociclib and LY294002 were used in combination with gefitinib to evaluate the effects on HNSCC cell cytotoxicity during hypoxia. Finally, metformin was used to evaluate the sensitizing effects of gefitinib treatment on HNSCC in vivo and in vitro.ResultsCell viability and apoptosis assays demonstrated a significant difference in HNSCC cells treated with gefitinib between the normoxia and hypoxia groups. Hypoxia induced the expression of cyclin D1, decreased the percentage of cells in G1, and promoted the EMT of tumor cells. Both palbociclib and LY294002 enhanced gefitinib-induced cytotoxicity of HNSCC cells under hypoxic conditions. Encouragingly, metformin sensitized HNSCC to gefitinib treatment in vivo and in vitro.ConclusionHypoxia promotes G1–S cell cycle progression and EMT in HNSCC, resulting in gefitinib treatment resistance. Metformin sensitizes HNSCC to gefitinib treatment, which might serve as a novel combined treatment strategy.

Abstract 1605: Cetuximab inhibits migration, invasion, metastasis and epithelial-mesenchymal transition but not proliferation via GEP100-Arf6-AMAP1 pathway in head and neck squamous cell carcinoma

Abstract Background: Recently, irradiation combined with Cetuximab (Cmab) is being one of the standard therapeutic options against head and neck squamous cell carcinoma (HNSCC), especially in advanced/recurrent cases. While this concurrent chemo-radiotherapy is widely accepted and tolerated, Cmab monotherapy has been reported to be unsatisfactory to treat HNSCC, and detailed mechanism of Cmab to show such clinical efficacy is unknown. Methods: To assess the impact of Cmab on proliferation, migration, and invasion of HNSCC, WST assay, wound healing assay, and matrigel invasion assay were incorporated in this study. Effects of Cmab on the grade of epithelial-mesenchymal transition (EMT), expression level of membrane type 1-matrix-metalloproteinase (MT1-MMP), and activity of EGFR-GEP100-Arf6-AMAP1 pathway, were evaluated using the immunocytochemistry, western blot analysis and Arf6 activation assay, respectively. Furthermore, In vivo efficacy of Cmab was evaluated in highly aggressive and metastatic HSC-3-M3 cells using orthotopic xenograft model in nude mice nu/nu. Results: Inhibition of migration and invasion were observed in 4 HNSCC cell lines by Cmab application. However, proliferation potential of HNSCC were not affected by this chemotherapeutic agent. Increased expression of E-cadherin, with decreased expression of N-cadherin and MT1-MMP, were observed after Cmab treatment in vitro to suggest that Cmab may inhibit EMT in HNSCC. Furthermore, inhibition of Tyr 1086 phosphorylation in EGFR, as well as the inactivation of Arf6 coupled with suppression of both GEP100 and AMAP1 expressions were observed by Cmab application. These results suggested that Cmab might have the potential to suppress the activity of EGFR-GEP100-Arf6-AMAP1 pathway. Furthermore, less metastasis of the cancer was observed in the Cmab treatment group compared with control group in vivo. Conclusions: Our study is the first to provide that Cmab could affect HNSCC through inhibition of migration and invasion of cancer cells, regardless of its anti-proliferative action. EMT inhibition after Cmab application was also clarified in this study. Furthermore, our study suggested that EGFR-GEP100-Arf6-AMAP1 pathway may have some role in the invasion and metastasis of HNSCC. Future studies to further assess the precise mechanism of Cmab against HNSCC are warranted. Citation Format: Yoshifumi Matsumoto, Hiroyuki Sakurai, Yasunao Kogashiwa, Koichiro Saito. Cetuximab inhibits migration, invasion, metastasis and epithelial-mesenchymal transition but not proliferation via GEP100-Arf6-AMAP1 pathway in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1605.

Snail-induced EMT promotes cancer stem cell-like properties in head and neck cancer cells.

Epithelial-mesenchymal transition (EMT) is a key process involved in the invasion and metastasis of cancer cells. Furthermore, EMT can induce a cancer stem cell (CSC)-like phenotype in a number of tumor types. We demonstrated that Snail is one of the master regulators that promotes EMT and mediates cancer cell migration and invasion in many types of malignancies including head and neck squamous cell carcinoma (HNSCC). In the present study, we investigated the role of Snail in inducing and maintaining CSC-like properties through EMT in HNSCC. We established HNSCC cell lines transfected with Snail. Stem cell markers were evaluated with real-time RT-PCR and western blot analysis. CSC properties were assessed using sphere formation and WST-8 assays as well as chemosensitivity and chick chorioallantoic membrane in vivo invasion assays. Introduction of Snail induced EMT properties in HNSCC cells. Moreover, Snail-induced EMT maintained the CSC-like phenotype, and enhanced sphere formation capability, chemoresistance and invasive ability. These data suggest that Snail could be one of the critical molecular targets for the development of therapeutic strategies for HNSCC.

Signaling Pathways Supporting Tumor Invasion in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly invasive cancer. A number of signaling pathways like PI3K, Rho and TGFβ/SMAD drive the invasive nature of HNSCC. The PI3K pathway is the most altered pathway in HNSCC. Both upstream and downstream members of this pathway have been found to be mutated or overexpressed leading to an increase in cell invasion. The Rho pathway is also commonly activated; however, only overexpression or downregulation of Rho’s upstream regulators are found in HNSCC. Finally, TGFβ/SMAD pathway activation leads to epithelial mesenchymal transition in HNSCC and subsequently invasion, though loss of TGFβ/ SMAD signaling has also been shown to increase cell invasion.

Abstract 1141: p53-dependent regulation of epithelial-to-mescenchymal transition by nf-κb in head and neck squamous cell carcinoma

Abstract PURPOSE: In head and neck squamous cell carcinoma (HNSCC), mutations of p53 usually coexist with aberrant activation of NF-kappaB (NF-κB) and other transcription factors which promote tumor pathogenesis. However, how these factors mediate oncogenesis and metastasis is not fully understood. Herein we investigate the mechanisms by which p53 and NF-κB contribute to Epithelial-Mesenchymal Transition (EMT) in HNSCC. EXPERIMENTAL DESIGN: We evaluated the effects of p65 mutation on the molecular events of EMT in surgical specimens and HNSCC cell lines. We examined the correlation with tumor histologic features. RESULTS: In HNSCC cell lines with mutant p53, p65 knockdown promotes EMT. In contrast, in normal oral epithelial cells or HNSCC cells with WT p53, p65 over-expression, instead of knockdown, promotes EMT. Ablation of p53 in normal oral epithelial cells blocks p65 induced EMT. These findings are functionally corroborated herein in three-dimensional cell culture, anchorage-independent growth assays, and tumor cell migration assays. CONCLUSIONS: This is the first report indicating the role of p53 status in the NF-κB -induced promotion of EMT in HNSCC. Bortezomib-based regimens have been shown to have minimal activity in recurrent or metastatic head and neck cancer. Our new findings are important in understanding a possible basis for these clinical findings as well as defining important implications for targeted chemoprevention and therapy. Citation Format: Yuan Lin, Jie Luo, Elliot Abemayor, Sherven Sharma, Steven Dubinett, Maie St John. p53-dependent regulation of epithelial-to-mescenchymal transition by nf-κb in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1141. doi:10.1158/1538-7445.AM2014-1141

Apricoxib upregulates 15-PGDH and PGT in tobacco-related epithelial malignancies

Background:Despite focused research in conventional therapies and considerable advances in the understanding of the molecular carcinogenesis of head and neck squamous cell carcinoma (HNSCC), the 5-year survival rate for patients with advanced disease remains ∼15–20%. The major causes of HNSCC-related deaths are cervical node and distant metastasis. E-cadherin has a key role in epithelial intercellular adhesion and its downregulation is a hallmark of epithelial–mesenchymal transition (EMT), which is associated with invasion, metastasis, and poor prognosis. Epithelial–mesenchymal transition is the major mechanism responsible for mediating invasiveness and metastasis of epithelial cancers. Recently, we reported the role of E-cadherin transcriptional repressors in the inflammation-induced promotion of EMT in HNSCC, which is mediated by COX-2. These findings suggest that therapies targeting the cyclooxygenase pathway may diminish the propensity for tumour metastasis in HNSCC by blocking the PGE2-mediated induction of E-cadherin transcriptional repressors.Methods:Herein, we evaluate the efficacy of the COX-2 inhibitor, apricoxib, in HNSCC cell lines. Apricoxib is effective in preventing tumour cell growth in three-dimensional, and anchorage-independent growth assays, as well as decreasing the capacity for tumour cell migration.Results:Herein, we evaluate the efficacy of the COX-2 inhibitor, apricoxib, in HNSCC cell lines. Apricoxib is effective in preventing tumour cell growth in three-dimensional, and anchorage-independent growth assays, as well as decreasing the capacity for tumour cell migration. Treatment of HNSCC cells with apricoxib also causes greater upregulation of E-cadherin and Muc1 expression and downregulation of vimentin, as compared with celecoxib treatment. This has significant implications for targeted chemoprevention and anti-cancer therapy because E-cadherin expression has been implicated as a marker of sensitivity to epidermal growth factor receptor tyrosine kinase inhibitor and other therapies. We show for the first time the molecular mechanisms underlying the efficacy of apricoxib in HNSCC cells.Conclusion:In addition to reversing EMT via inhibition of COX-2, apricoxib upregulates 15-prostaglandin dehydrogenase and the prostaglandin transporter, thereby reducing the levels of active PGE2 by both suppressing its synthesis and increasing its catabolism. These findings have significant implications for metastasis and tumour progression in HNSCC.

The role of ZEB1 in the inflammation-induced promotion of EMT in HNSCC

Objectives To determine the role of ZEB1 in the inflammation-induced promotion of the epithelial-mesenchymal transition (EMT) in head and neck squamous cell carcinoma (HNSCC). Study Design A molecular biology study. Real-time quantitative reverse-transcriptase polymerase chain reaction (RT-PCR), Western blot analysis, and immunohistochemical staining of human HNSCC tissue sections were used to determine how inflammation affects the transcriptional repressor, ZEB1. Setting An academic hospital laboratory. Subjects and Methods Relative ZEB1 RNA levels were determined by RT-PCR, and protein expression was evaluated in situ by immunohistochemical staining of human HNSCC tissue sections. Results IL-1β-treated HNSCC cell lines demonstrated a significant decrease in E-cadherin mRNA and an increase in the mRNA expression of the transcriptional repressor ZEB1. IL-1β exposure led to enhanced ZEB1 binding at the chromatin level, as determined by chromatin immunoprecipitation assays (ChIP). An inverse relationship between ZEB1 and E-cadherin was demonstrated in situ by immunohistochemical staining of human HNSCC tissue sections. Conclusions Our recent investigations indicate that inflammatory mediators are potent regulators of EMT in HNSCC. This is the first report indicating the role of ZEB1 in the inflammation-induced promotion of EMT in HNSCC. This newly defined pathway for transcriptional regulation of E-cadherin in HNSCC has important implications for targeted chemoprevention and therapy.

Relation between proinflammatory mediators and epithelial-mesenchymal transition in head and neck squamous cell carcinoma

Increasing evidence suggests that the tumor microenvironment plays an important role in tumor progression and oncogenesis. Various proinflammatory mediators contribute to tumor proliferation, neoangiogenesis, invasion, metastasis, and resistance to cancer therapy such as hormonal therapy and chemotherapy. The major causes of death related to head and neck squamous cell carcinoma (HNSCC) include cervical node and distant metastases. Epithelial-mesenchymal transition (EMT) has been identified to play a key role in mediating the tumor invasion and metastasis of carcinomas. Herein, the relationship between proinflammatory mediators and EMT in HNSCC was investigated. Immunohistochemical expression of interleukin-1 β (IL-1β), cyclooxygenase-2 (COX-2), Slug and E-cadherin in relationship to histologic differentiation, clinical stage and nodal status was evaluated in 146 surgical specimens of HNSCC. A correlation was noted between increased expression of IL-1β and nodal status, as well as increased expression of COX-2 and histologic differentiation, clinical stage and nodal status. Increased Slug expression was correlated with histologic differentiation and clinical stage. Decreased E-cadherin expression was correlated with histologic differentiation and nodal status. A significant relationship was observed between IL-1β and COX-2. However, a significant inverse correlation was noted between Slug and E-cadherin. A significant relationship was observed between increased proinflammatory mediator IL-1β/COX-2 expression and increased EMT marker Slug/E-cadherin expression. These results indicate that proinflammatory mediators IL-1β and COX-2 may induce EMT through an increase in Slug and a decrease in E-cadherin. The present findings suggest that various anti-inflammatory agents could be used as an adjuvant treatment modality with anti-cancer chemotherapeutic drugs in HNSCC.

Proinflammatory Mediators Upregulate Snail in Head and Neck Squamous Cell Carcinoma

Inflammatory cytokines have been implicated in the progression of head and neck squamous cell carcinoma (HNSCC). Herein we investigate the mechanisms by which interleukin-1beta (IL-1beta) might contribute to Epithelial-Mesenchymal Transition (EMT) in HNSCC. We evaluated the effect of IL-1beta on the molecular events of EMT in surgical specimens and HNSCC cell lines. We examined the correlation with tumor histologic features, and a SCID xenograft model was used to assess the effects of Snail overexpression. Cyclooxygenase-2 (COX-2)-dependent pathways contribute to the modulation of E-cadherin expression in HNSCC. An inverse relationship between COX-2 and E-cadherin was shown in situ by double immunohistochemical staining of human HNSCC tissue sections. Treatment of HNSCC cells with IL-1beta caused the downregulation of E-cadherin expression and upregulation of COX-2 expression. This effect was blocked in the presence of COX-2 small hairpin RNA. IL-1beta-treated HNSCC cell lines showed a significant decrease in E-cadherin mRNA and an increase in the mRNA expression of the transcriptional repressor Snail. IL-1beta exposure led to enhanced Snail binding at the chromatin level. Small hairpin RNA-mediated knockdown of Snail interrupted the capacity of IL-1beta to downregulate E-cadherin. In a SCID xenograft model, HNSCC Snail-overexpressing cells showed significantly increased primary and metastatic tumor burdens. IL-1beta modulates Snail and thereby regulates COX-2-dependent E-cadherin expression in HNSCC. This is the first report indicating the role of Snail in the inflammation-induced promotion of EMT in HNSCC. This newly defined pathway for transcriptional regulation of E-cadherin in HNSCC has important implications for targeted chemoprevention and therapy.