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Emerging studies have demonstrated that long non‑coding RNAs (lncRNAs) play essential roles in tumorigenesis. However, the role and function of lncRNAs in hypopharyngeal squamous cell carcinoma (HSCC) have not been completely elucidated. The present study explored the function of a novel lncRNA, RP11‑156L14.1, in HSCC. RP11‑156L14.1 was revealed to be highly expressed in HSCC tissues and cell lines. Knockdown of RP11‑156L14.1 inhibited proliferation, migration, and invasion in HSCC cells. Furthermore, RP11‑156L14.1 regulated epithelial‑mesenchymal transition (EMT) by controlling EMT‑related protein expression. Mechanistically, RP11‑156L14.1 exerted its function as a competing endogenous RNA (ceRNA) and directly interacted with miR‑548ao‑3p. The present study also demonstrated that miR‑548ao‑3p regulated signal sequence receptor subunit 1 (SSR1) expression by targeting SSR1 3'‑UTR. Moreover, the xenograft HSCC tumor model revealed that knockdown of RP11‑156L14.1 markedly suppressed HSCC tumor growth in vivo. In summary, these findings indicated that the lncRNA RP11‑156L14.1 functions as an oncogene in HSCC by competing with miR‑548ao‑3p in regulating SSR1 expression. The RP11‑156L14.1/miR‑548ao‑3p/SSR1 axis could be utilized as a potential novel biomarker and therapeutic target for HSCC.

The present study aimed to investigate the clinical relevance of circulating tumor cells (CTCs) in patients with locally advanced head and neck squamous cell carcinoma (LA‑HNSCC), particularly in patients with nasopharyngeal and hypopharyngeal squamous cell carcinoma. CTCs were isolated using negative immunomagnetic bead enrichment and were identified by fluorescence in situ hybridization. Youden's index and the receiver operating characteristic (ROC) curve were used to select the optimal CTC baseline value. χ2 test or Fisher's test were used to determine the association between CTC counts and clinical parameters, curative effects and prognosis. The Kaplan‑Meier estimator was used to analyze overall survival (OS) and progression‑free survival (PFS). In the present study, 356 peripheral blood samples (178 pretreatment samples and 178 post‑treatment samples) from 178 patients were examined. The results revealed that the pretreatment CTC detection rate was 73.8%. The minimum, maximum and median CTC counts were 1, 22 and 2/3.2 ml, respectively. The number of polyploid CTCs was associated with distant metastasis (P=0.026). In addition, patients with undetectable CTCs, and decreasing or negative CTCs post‑treatment tended to have a good prognosis (P<0.05). For nasopharyngeal squamous cell carcinoma, the PFS of patients with increased CTCs and CTCs ≥2/3.2 ml after treatment was significantly lower (P<0.05). For hypopharyngeal squamous cell carcinoma, it was suggested that CTCs with a cutoff value of 3 may be used to evaluate PFS and OS before and after treatment. In conclusion, CTCs may be used to monitor disease progression and the response to chemoradiotherapy for patients with LA‑HNSCC. Furthermore, CTCs are a better predictor of the prognosis of hypopharyngeal squamous cell carcinoma than that of nasopharyngeal squamous cell carcinoma.

Hypopharyngeal carcinoma (HPC) is an aggressive malignancy with the worst prognosis among all head and neck cancers. MicroRNAs (miRNAs) are involved in the development of many human cancers, and may function as oncogenes or tumor suppressors. The present study aimed to evaluate the effects of miRNA (miR)‑194‑5p on the proliferation and invasion of HPC cells and to identify the potential regulatory mechanism. First, miR‑194‑5p and Smad ubiquitin regulatory factor 1 (SMURF1) expression levels were examined in HPC tissues. Subsequently, to explore the effects of miR‑194‑5p on SMURF1, a dual‑luciferase reporter gene assay was performed to verify the target relationship. To define the role of miR‑194‑5p in HPC progression, miR‑194‑5p upregulation and depletion were used to evaluate its effects on cell viability, invasion and migration. SMURF1 silencing and rapamycin [an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway] treatment were also used to analyze the regulatory mechanism in HPC. Finally, tumor growth was assessed in xenografted tumors in nude mice. SMURF1 was demonstrated to be highly expressed, whereas miR‑194‑5p was poorly expressed in HPC tissues; SMURF1 was identified as a target gene of miR‑194‑5p. FaDu hypopharyngeal squamous cell carcinoma cells treated with miR‑194‑5p mimics exhibited decreased viability, invasion and migration. The results indicated that miR‑194‑5p may inactivate the mTOR signaling pathway by targeting SMURF1. In addition, the in vivo experiments further verified these regulatory effects. These data suggested that miR‑194‑5p‑targeted SMURF1 inhibition may be involved in the disruption of HPC progression through the repression of the mTOR signaling pathway.

Laryngeal carcinoma is one of the most common tumors concerning otorhinolaryngology head and neck surgery, however, the pathogenesis of laryngeal carcinoma remains unclear. MicroRNAs (miRNAs) have been reported to play vital roles in the pathogenesis of laryngeal carcinoma Herein, the present study was designed to explore the function and mechanism of miRNA‑98 in hypopharyngeal carcinoma. In brief, qRT‑PCR, MTT assay, western blot analysis, Transwell assay and luciferase reporter assay were performed. Based on the results, miRNA‑98 expression was downregulated in patients with hypopharyngeal carcinoma. Downregulation of miRNA‑98 promoted cell growth and migration, and decreased the apoptotic rate of hypopharyngeal carcinoma cells. Overexpression of miRNA‑98 increased the apoptotic rate, and inhibited cell growth and migration of hypopharyngeal carcinoma cells. Moreover, luciferase reporter assays revealed that MTDH is a direct target of miRNA‑98 and overexpression of miRNA‑98 induced the protein expression of PTEN and suppressed that of PI3K and p‑Akt. si‑MTDH attenuated the anticancer effects of miRNA‑98 on hypopharyngeal carcinoma via the PTEN/AKT pathway. To the best of our knowledge, the present study confirmed for the first time that miRNA‑98 inhibits hypopharyngeal carcinoma cell proliferation and induces apoptosis via the PTEN/AKT pathway by MTDH.

Accumulating evidence has suggested that circular RNAs (circRNAs), a novel class of non‑coding RNAs, have crucial roles in tumor progression. However, the significance of circRNAs in hypopharyngeal cancer (HCa) remains to be investigated. The present study has identified aberrantly expressed circRNAs by performing circRNA sequencing analyses of three pairs of tumor and adjacent normal samples from patients with HCa. The results demonstrated that 173 circRNAs were differentially expressed (DE), including 71 upregulated and 102 downregulated circRNAs (FDR<0.05 and fold changes of ≥2 or ≤0.5 by Mann‑Whitney U test followed by Benjamini‑Hochberg correction for multiple testing). Pathway analyses of the genes producing DE circRNAs revealed that many of them were involved in cancer‑related pathways. To further illustrate the roles of circRNAs in HCa progression, a competing endogenous RNA (ceRNAs) network was constructed, consisting of circRNAs, miRNA, and miRNA targeted genes. The results demonstrated that multiple cancer‑related pathways were affected by performing enrichment analyses of the targeted genes. Of note, a ceRNA subnetwork was isolated, consisting of two circRNAs (hsa&#95;circ&#95;0008287 and hsa&#95;circ&#95;0005027) and one miRNA (hsa‑miR‑548c‑3p), which significantly affect both ErbB and Hippo signaling pathways. In conclusion, the present study identified a set of circRNAs that are potentially implicated in the tumorigenesis of HCa and may serve as potential biomarkers for the diagnosis of HCa.

The present study aimed to investigate the effects of photothermal therapy with gold nanorods (AuNRs) or epidermal growth factor receptor monoclonal antibody‑conjugated AuNRs (EGFRmAb‑AuNRs) on hypopharyngeal carcinoma (HC) in nude mice. In addition, the associated signaling pathways were explored. Briefly, a subcutaneous transplantable hypopharyngeal tumor model was established in nude mice injected with FaDu human HC cells. A total of 70 nude mice were randomly divided into seven groups, each of which received a different treatment. Mice were treated with AuNRs, locally or through intravenous injection, whereas EGFRmAb or EGFRmAb‑AuNRs were only administered locally. Near infrared spectroscopy (NIR) was also applied for plasmonic photothermal therapy (PPTT). The growth curve and the inhibitory rate for tumor growth were used to evaluate the effects of each treatment. Flow cytometry and the terminal‑deoxynucleotidyl transferase dUTP nick end labeling assay were adopted to detect apoptosis of cells in the transplanted tumors. Reverse transcription‑quantitative polymerase chain reaction and western blotting were used to determine the mRNA and protein expression levels of target genes, respectively. Local treatment with AuNRs + NIR or EGFRmAb significantly inhibited tumor growth, and EGFRmAb conjugation further increased the inhibitory effects. Furthermore, there was a significant increase in apoptosis of tumor cells in the AuNRs + NIR, EGFRmAb and EGFRmAb‑AuNRs + NIR groups; treatment with EGFRmAb‑AuNRs + NIR induced the highest apoptotic effect. Mechanistic studies indicated that EGFRmAb‑AuNRs + NIR may inhibit tumors through the AKT serine/threonine kinase (Akt) and DNA damage signaling pathways. In the AKT pathway, the mRNA and protein expression levels of phosphatase and tensin homolog were increased, whereas the expression levels of Akt and glycogen synthase kinase 3β were decreased. In the DNA damage signaling pathway, the mRNA and protein expression levels of ATR serine/threonine kinase, checkpoint kinase 1 and p53 were enhanced, whereas phosphorylated‑p53 protein expression was reduced. The present findings indicated that AuNRs + NIR inhibited HC tumor growth, and conjugating EGFRmAb to AuNRs further enhanced the inhibitory effects. EGFRmAb conjugation may increase the antitumor effects of AuNRs‑induced PPTT by downregulating the phosphatidylinositol‑3‑kinase/Akt pathway and upregulating the DNA damage pathway. These findings may provide novel insights into tumor‑targeting PPTT in vivo.

The aim of the present study was to investigate the key genes, miRNAs and pathways in hypopharyngeal squamous cell carcinoma (HPSCC) and to elucidate the mechanisms underlying HPSCC development. The gene and microRNA (miRNA) expression profiles of HPSCC tissues and adjacent normal tissues from three subjects were obtained. Differentially expressed genes (DEGs) and differentially expressed miRNAs were identified in HPSCC. Functional annotation and protein‑protein interaction (PPI) network were conducted to elucidate the biological functions of DEGs. A total of 160 DEGs (16 upregulated and 144 downregulated genes) and 79 differentially expressed miRNAs (48 upregulated and 31 downregulated miRNAs) were identified in HPSCC. The deregulated genes were significantly involved in spliceosome, cell cycle and RNA degradation. In the PPI network, S‑phase kinase associated protein 1 (SKP1), non‑POU domain containing octamer binding (NONO) and zinc activated ion channel (ZACN) were identified as hub proteins. On the whole, the present study may help to gain a comprehensive understanding of tumorigenesis in HPSCC and provide valuable information for early diagnosis and drug design of HPSCC in future research.

Forkhead box M1 (FoxM1), a member of the Fox family of transcriptional factors, is involved in the development of various human malignancies. However, the expression level of FoxM1 and its functional role in hypopharyngeal squamous cell carcinoma (HSCC) remained unclear to date. The aim of the present study was to investigate the FoxM1 expression in 63 HSCC and 20 adjacent normal tissues, as well as to evaluate its association with the clinicopathological parameters and its diagnostic value in HSCC. To further explore the biological function of FoxM1 in vitro, siRNAs were used to knockdown the expression of FoxM1 in the HSCC cell line Fadu. The results revealed that FoxM1 protein was highly expressed in HSCC tissues and that its high expression was closely associated with HSCC tumor differentiation (P=0.004), tumor size (P=0.002), clinical stage (P=0.001), lymph node metastasis (P=0.002), treatment (P=0.045) and expression of the proliferation marker Ki-67 (P<0.001). Additionally, the elevated expression of FoxM1 in HSCC patients consistently predicted a poor survival time. Knockdown of FoxM1 expression blocked Fadu cell proliferation and promoted apoptosis, and also led to the downregulation of cyclin A1 expression. Furthermore, decreased expression of FoxM1 markedly impeded cell migration and reversed the epithelial-mesenchymal transition phenotype, as indicated by decreased expression of vimentin and increased expression of E-cadherin in Fadu cells. These results indicate that FoxM1 may act as an oncogene and serve as a therapeutic target against malignant progression in HSCC.

The aim of this study was to determine the effect of A disintegrin and metalloprotease 10 (ADAM10) protein expression on the progression, migration and prognosis of hypopharyngeal squamous cell carcinoma (HSCC). Immunohistochemistry and western blot analysis were performed to detect ADAM10 expression in human HSCC specimens. Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis and wound-healing assay were employed to investigate the effects of ADAM10 knockdown (ADAM10-RNAi) on major oncogenic properties of FaDu cells. We detected that ADAM10 was overexpressed in HSCC specimens and its expression level was associated with differentiation (p<0.001), tumor size (p=0.019), lymph node metastasis (p=0.001), clinical stage (p<0.001), proliferation marker Ki-67 expression (P=0.001) and overall survival (p<0.046). ADAM10-RNAi in FaDu cells resulted in the inhibition of proliferation and the decrease in migration. Moreover, mechanistic experiments revealed that ADAM10-RNAi resulted in an increase in E-cadherin and a decrease in N-cadherin and vimentin expression. Our study implies that high expression of ADAM10 promotes the proliferation and migration of HSCC. These findings may help to provide a method for treatment of HSCC.

Stathmin1, a microtubule-destabilizing phosphoprotein, is considered to play a crucial role in regulating cellular microtubule dynamics and controlling mitosis. Previous studies have showed that STMN1 is highly expressed in many human malignancies and is related to development, invasion and metastasis of tumors. However, its expression pattern, clinical performance and functional roles in hypopharyngeal squamous cell carcinoma (HSCC) have not been addressed. In this study, we found that STMN1 was significantly elevated in HSCC and its expression level was correlated with poor differentiation (P<0.001), clinical stage (P<0.001), large tumor size (P=0.001) and lymph node metastasis (P=0.008). A positive correlation between STMN1 and Ki‑67 expression was also exhibited. High STMN1 expression predicted poor survival. Furthermore, we found that knockdown of STMN1 by siRNAs inhibited the FaDu cell proliferation and migration. Moreover, decreased STMN1 expression in FaDu cells reversed the acquisition of EMT phenotype by upregulating E-cadherin, as well as reduced vimentin expression at protein and mRNA levels. These results suggested that STMN1 plays an important role in proliferation and migration of HSCC and may be used as a potential prognostic biomarker or therapeutic target of HSCC.

Aberrant expression of miR-15a was recently reported in several types of cancers; however, its role in HPV-positive hypopharyngeal squamous cell carcinoma (HSCC) remains obscure. In the present study, we investigated the mechanism by which miR-15a induces HPV-positive HSCC apoptosis. Synthetic miR-15a mimics were transfected into FaDu cells (HPV-negative), and the miR-15a inhibitor was transfected into HPV-positive HSCC cells. miR-15a expression was analyzed by RT-PCR, and BCL2L2 and BCL2 were analyzed by western blotting. The Hochest 33342/propidium iodide (PI) and caspase-3/-9 assays, and Annexin V staining were used to assess the effect of miR-15a on apoptosis. After transfection, overexpression of miR-15a in the FaDu cells was associated with significantly decreased BCL2L2 and BCL2 expression and a significant increase in the apoptosis rate. The opposite results were observed in HPV-positive HSCC, where downregulation of miR-15a suppressed apoptosis. These findings indicate that miR-15a acts as a tumor suppressor in HPV-positive HSCC.

Hypopharyngeal squamous cell carcinoma (HSCC) is one of the most common head and neck cancers with high invasiveness and poor prognosis. To identify targeted therapeutics against metastasis, a better understanding of the regulation of HSCC cell invasion is needed. In recent years, G protein-coupled receptor kinases (GRKs) have been implicated in cancer metastasis through phosphorylation of the activated form of G protein coupled receptors (GPCRs). However, there is little information regarding GRKs expression in HSCC. In the present study, we examined GRK6 expression in HSCC and also assessed the possible cause of its aberrant expression, as well as its clinical significance. Real-time quantitative PCR (qPCR) and western blotting were performed to analyze the expression of GRK6 in HSCC tissues and corresponding non-malignant tissues. Subsequently, paired HSCC and corresponding non-malignant tissues were evaluated for the methylation status of GRK6 gene promoter using methylation-specific PCR (MSP). Furthermore, we investigated the methylation status and the clinicopathological significance of GRK6 in 45 paired HSCC and corresponding non-malignant tissues. The suppression of GRK6 in hypopharyngeal cell line FaDu by GRK6-shRNA lentivirus transfection was utilized to detect the role of GRK6 in hypopharyngeal cancer progression. Our results showed that the expression of GRK6 mRNA and protein was significantly lower in HSCC than in corresponding adjacent non-tumor tissues, and this downregulation was found to be in accordance with aberrant methylation of the gene. Hypermethylation of the gene was observed in 77.8% (35/45) of the HSCC tissues, while it was found in only 42.2% (19/45) of the corresponding non-malignant tissues. GRK6 methylation was related to depth of tumor invasion and TNM stage. Upon treatment with 5-aza-2'-deoxycytidine, GRK6 expression was upregulated in FaDu cells, and cell invasion was signinficantly inhibited. Furthermore, the suppression of GRK6 by shRNA transfection enhanced FaDu cells invasion. Our results indicate that the aberrant methylation of GRK6 gene promoter may underlie its downregulation in HSCC, and may play an important role in the metastasis of HSCC.

Hypopharyngeal squamous cell carcinoma is a common type of malignant tumor among head and neck squamous cell carcinomas (HNSCCs). Heavy smoking and/or drinking is associated with the development of HNSCC. However, HNSCC also occurs in individuals that do not drink or smoke, possibly due to infection with the human papilloma virus (HPV). HPV-16 has been shown to be closely associated with the occurrence of several types of cancers. However, its role in hypopharyngeal squamous cell carcinoma remains unclear. In the present study, we investigated the effects of HPV-16 on hypopharyngeal squamous cell carcinoma and FaDu cells. Lentiviral vectors were used to establish FaDu cells that expressed the E6 and E7 proteins of HPV-16. We used quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assays and western blotting to detect and determine the levels of expression for E6-E7 mRNAs and proteins. Cell Counting Kit-8 (CCK-8) assays, enzyme-linked immunosorbent assays (ELISA), Transwell assays, and flow cytometry were used to assess the effects of HPV-16 E6-E7 on the proliferation, invasion, metastasis and apoptosis of FaDu cells. Expression of microRNAs was analyzed by qRT-PCR. We found that the expression levels of HPV-16 E6-E7 were increased in FaDu cells transfected with the lentiviral vector compared with that observed in the control cells. In addition, the rates of apoptosis were decreased in the transfected cells, while proliferation was increased. The average numbers of cells penetrating the Matrigel were significantly higher than those for the controls. We detected miR-363 and miR-15a, and their expression levels were significantly increased in the HPV-16-positive patients and in FaDu cells expressing HPV-16 E6-E7. We found that HPV-16 E6-E7 appeared to inhibit apoptosis, and to increase cell proliferation, invasion and metastasis. Furthermore, miR-363 and miR-15a were overexpressed in the hypopharyngeal squamous cell carcinoma samples infected with HPV-16, and in FaDu cells stably expressing HPV-16 E6-E7. These findings may provide a new clue of the mechanisms involved in the pathogenesis of HPV-16-positive hypopharyngeal squamous cell carcinoma.

Epidermal growth factor receptor (EGFR) signaling plays an important role in tumor cell resistance to therapy. In addition to ligand binding, mutual and cooperative interactions of EGFR with integrin cell adhesion receptors critically influence proper downstream signaling through a number of bridging adapter proteins. In the present study, we analyzed the role of two of these adapter proteins, called PINCH1 and Nck2, for cellular radioresistance in combination with EGFR-targeting using the monoclonal antibody cetuximab. siRNA-mediated knockdown of PINCH1 or Nck2 resulted in enhanced radiosensitivity of 3D grown human squamous cell carcinoma cell lines FaDu (head and neck) and A431 (epidermis) comparable with effects seen after cetuximab treatment. Combination of knockdown and cetuximab did not result in additive nor synergistic effects regarding clonogenic radiation survival. Modifications in MAPK, Akt and FAK phosphorylation occurred upon cetuximab treatment as well as PINCH1 or Nck2 depletion. We further found this tumor cell radiosensitization to be due to attenuated repair of DNA double strand breaks and altered Rad50 and Nbs1 expression but without changes in other DNA repair proteins such as ATM, DNA-PK and Mre11. Our data suggest that the adaptor proteins PINCH1 and Nck2 critically contribute to cellular radioresistance and proper EGFR signaling in 3D lrECM grown human squamous cell carcinoma cells. Further investigations are warranted to identify the intracellular signaling network controlled by EGFR, PINCH1 and Nck2.

Our recent study of the microRNA (miRNA) expression signature of hypopharyngeal squamous cell carcinoma (HSCC) revealed that microRNA-504 (miR-504) is significantly downregulated in HSCC tissues, suggesting that this miRNA is a candidate tumor suppressor. However, several previous reports indicated that miR-504 has an oncogenic function through targeting TP53. The aim of this study was to investigate the functional significance of miR-504 in cancer cells and to identify novel targets regulated by this miRNA in HSCC cells. First, we confirmed the downregulation of miR-504 in HSCC clinical specimens (P<0.0001) by qPCR. Using two sources of miR-504 to restore function, we observed significant inhibition of cancer cell proliferation in head and neck SCC (HNSCC) cell lines (FaDu, SAS and HSC3) and HCT116 colon carcinoma cells (p53+/+ and p53-/-). In HNSCC cells, induction of cell cycle arrest was observed by miR-504 transfection. To identify the molecular targets of miR-504, we performed gene expression analysis of miR-504 transfectants and in silico database analyses. Our data showed that cell cycle-related genes (RB1, CDK6, CDC23 and CCND1) were candidate target genes of miR-504. In HSCC clinical specimens, the expression of cyclin-dependent kinase 6 (CDK6) was significantly higher in cancer tissues compared to non-cancer tissues (P=0.0004). A significant inverse correlation between CDK6 and miR-504 expression was found (r=-0.43, P=0.0039). Expression of miR-504 inhibited CDK6 expression in HNSCC cells. Loss of tumor-suppressive miR-504 enhanced HSCC cell proliferation through targeting CDK6. The identification of novel tumor-suppressive miR-504-mediated molecular pathways and targets provide new insights into HSCC oncogenesis.

Identification of a reliable biomarker for predicting prognosis in head and neck cancers is highly desirable and has long been sought. There have been several reports that members of the regenerating gene (REG) family are highly expressed in chronic inflammation and in tumors of the digestive organs. In addition, it has been described in several reports that REG expression is associated with the progression of digestive cancers. In the present study, we evaluated the effect of REG expression on the prognosis of hypopharyngeal cancer. We investigated 37 cases with hypopharyngeal squamous cell carcinoma, determined REG mRNA expression, which is easily detected in formalin-fixed paraffin-embedded tissues using the real-time reverse transcriptase-polymerase chain reaction method, and evaluated the survival rate using the Kaplan-Meier method. According to these results, REG III mRNA expression was significantly associated with prolonged survival. Therefore, we constructed hypopharyngeal cancer cell lines transfected with REG III and assessed the cell proliferation and chemosensitivity and/or radiosensitivity in vitro. Cells transfected with REG III exhibited significantly lower cell proliferation and higher chemosensitivity and/or radiosensitivity compared with the control cells. These data suggest that REG III may be a reliable biomarker of prognosis in hypopharyngeal cancer. This is the first report concerning the association of REG III expression and the prognosis of head and neck squamous cell carcinoma including hypopharyngeal cancer.

The transcription factor TWIST is an important factor in regulating epithelial-mesenchymal transition (EMT) and tumor metastasis. To explore the functions of TWIST in hypopharyngeal cancer, we investigated if overexpression of TWIST has an effect on FaDu cell morphology, and if alteration of TWIST has an effect on E-cadherin, N-cadherin, c-fos, MMP-9, as well as in cell migration, and the invasion ability of FaDu cells. Moreover, we also studied the relationship between TWIST overexpression and clinicopathological characteristics in hypopharyngeal cancer tissue samples by immunohistochemical assays. The results showed that overexpression of TWIST-induced morphological changes, such as occurrence of EMT. TWIST overexpression also increased cell migration and invasion ability, accompanied by an alteration of E-cadherin, N-cadherin, c-fos and MMP-9 expression. Furthermore, immunohistochemical assays showed that TWIST overexpression was related with tumor differentiation (P=0.038), tumor size (P=0.048) and lymph node metastasis (P=0.044). The data presented reveal that overexpression of TWIST plays a significant role in the metastasis of hypopharyngeal tumors, and alteration of TWIST has an effect on the EMT, c-fos and MMP-9 expression in FaDu cells. We conclude that TWIST promotes hypopharyngeal carcinoma metastasis, and the TWIST/c-fos/MMP-9 signaling pathway may play an important role in the metastasis of FaDu cells.

The major obstacle to tumor chemotherapy is drug resistance. In the present study, we investigated the characteristics of FaDu cells (a hypopharyngeal carcinoma cell line) with multidrug resistance (MDR) induced by Taxol. The resistant cell line, FaDu/T, was grown by exposing normal FaDu cells to escalating concentrations of Taxol stepwise for over 12 months. The multidrug resistant sensitivities of the FaDu/T cells to cisplatin (DDP), 5-fluorouracil (5-FU), doxorubicin (Dox) and vincristine (VCR) were investigated by methyl-thiazolyl-tetrazolium (MTT) assay. Cell apoptosis was measured by acridine orange and Hoechst 33342/propidium iodide double staining. Cell cycle distribution and the cell apoptosis index were quantified using flow cytometry. Reverse transcription-polymerase chain reaction (RT-PCR) was conducted to determine the mRNA levels of the MDR-related genes MDR1/ABCB1 and BCRP/ABCG2. Western blotting was used to assay the expression of MDR1/ABCB1 and BCRP/ABCG2 and the apoptosis-related proteins caspase-3, Bcl-2 and Bax. Compared with the FaDu cells, the drug resistance of FaDu/T cells to DDP, 5-FU, Dox and VCR was increased 8.99-, 21.96-, 31.42- and 10.00-fold, respectively. The percentages of FaDu/T cells in the G0/G1 and G2/M phases were increased while the cell percentage in the S phase decreased as compared with the percentages of FaDu cells. The anti-apoptotic ability increased prominently, as the index of apoptosis decreased. Furthermore, caspase-3, Bcl-2 and Bax expression was altered accordingly to resist apoptosis in the FaDu/T cells. MDR1/ABCB1 expression increased significantly at both the mRNA and protein levels, while BCRP/ABCG2 expression appeared to inversely affected, i.e. decreased, in a concentration-dependent manner. These -findings may provide theoretical support for the prevention of MDR in clinical cancer chemotherapy.

High levels of mitotic progression-associated PLK1 and stress-associated HSF1 have been observed in various human cancers. In the present study, we investigated the effects of PLK1 and HSF1 knockdown on the proliferation of oral cancer cells using small interfering RNA. In human oral squamous cell carcinoma (SCC) tissues, the levels of PLK1 and HSF1 were higher compared to normal tissues. The expression levels of PLK1 and HSF1 were also elevated in the human oral SCC cell lines FaDu and HEp-2. Disruption of PLK1 induced cell cycle arrest at G2/M phase as well as apoptosis in oral cancer cells. Interestingly, knockdown of both PLK1 and HSF1 expression decreased cell proliferation while increasing apoptotic cell death in synergistic fashion. These results establish the potential value of PLK1 and HSF1 as targets for oral cancer therapy.

Multiple chromosomal aberrations have been reported in head and neck squamous cell carcinoma (HNSCC). But less information is available on specific patterns of chromosomal amplifications which distinguish different areas of head and neck tumors. To elucidate genetic mechanisms causing the aggressive growth and high proliferation of hypopharyngeal squamous cell carcinoma (SCC), we performed reverse chromosome painting (RCP) on a total of eight hypopharyngeal SCC including invasive carcinoma and preinvasive tissue. Five hypopharyngeal invasive carcinomas showed amplifications on chromosome 3q. Furthermore, we detected gains on chromosomes 11q and 6p. Compared to the histologically classified preinvasive tissues, we found amplified alterations on chromosome 6p, 11q and 12q, but none of them showed gains on chromosome 3q. This observed heterogeneity in hypopharyngeal SCC might reflect a specific role of chromosome 3q as a late event in the highly invasive capacity of these SCC.