Hypopharyngeal Squamous Cell Carcinoma Tissues Research Articles

Upregulation of fascin-1 is involved in HIF-1α-dependent invasion and migration of hypopharyngeal squamous cell carcinoma.

Fascin-1 is an actin-bundling protein, which specifically interacts with F-actin to form parallel actin bundles, and participates in the regulation of cell adhesion, interactions and migration. However, the expression and regulatory mechanisms of fascin-1 in hypopharyngeal squamous cell carcinoma (HSCC) remain poorly understood. The present study investigated the effects and underlying molecular mechanism of fascin-1 on the invasion and metastasis of HSCC. The results demonstrated that fascin-1 was overexpressed and correlated with lymph node metastasis and tumor-node-metastasis stage in HSCC tissues. Further in vitro study revealed that fascin-1 promoted cell morphology polarization to increase the motility of FaDu cells. In addition, fascin-1 significantly promoted the migration and invasion of FaDu cells. At the molecular level, fascin-1 promoted cell invasion and migration by upregulating matrix metalloproteinase-2 (MMP-2) expression in FaDu cells. Immunohistochemical analysis revealed that a correlation existed between hypoxia inducible factor (HIF)-1α and fascin-1 expression in the HSCC tissues. Furthermore, the results from a cobalt chloride-induced hypoxia model demonstrated that fascin-1 may be upregulated by HIF-1α in FaDu cells. Further analysis revealed that fascin-1 knockdown significantly decreased the invasion of cells under hypoxia and partially reversed hypoxia-induced MMP-2 expression under hypoxia in FaDu cells. In conclusion, fascin-1 was upregulated by HIF-1α, and promoted the invasion and migration of HSCC cells; therefore, fascin-1 may provide a potential target for the treatment of invasion and metastasis in HSCC.

Low expression of AIM2 combined with high expression of p‑STAT3 is associated with poor prognosis in hypopharyngeal squamous cell carcinoma.

Studies indicate that the AIM2 inflammasome plays an important role in tumor occurrence and development. The present study examined the prognostic significance of AIM2 expression and the correlation between AIM2 expression and p‑STAT3 expression in hypopharyngeal squamous cell carcinoma (HSCC), which remain unknown. AIM2 and p‑STAT3 were detected using immunohistochemistry (IHC) in 111 paraffin‑embedded tissue samples from primary HSCC sites and 20 samples from matched adjacent non‑malignant sites. Western blotting was utilized to investigate AIM2, p‑STAT3 and total STAT3 in 5 pairs of fresh tissue samples. Western blotting indicated that AIM2 expression was significantly lower (P<0.05), but that p‑STAT3 levels and the p‑STAT3/STAT3 ratio were higher (P<0.01) in HSCC tissues than in adjacent normal hypopharyngeal tissues. IHC analysis of the 111 HSCC samples revealed low AIM2 and high p‑STAT3 expression in 48 (43.2%) and 58 (52.3%) samples, respectively. High AIM2 expression and low p‑STAT3 expression were detected in 13 (75%) and 18 (90%) adjacent normal hypopharyngeal tissue samples, respectively. In the HSCC samples, low AIM2 expression was closely related to lymph node metastasis and intravascular tumor thrombus (P<0.05). Kaplan‑Meier survival curves revealed that low AIM2 levels were strongly associated with poor survival for HSCC patients (P<0.0001). Additionally, Cox proportional hazards regression models indicated that low AIM2 expression significantly predicted poor prognosis for HSCC patients (P<0.0001), and multivariate analysis revealed that AIM2 expression could be an independent prognostic factor for HSCC patients (P<0.0001). Furthermore, AIM2 expression was negatively correlated with p‑STAT3 expression in the HSCC tissue samples, and combined analysis revealed that patients with low AIM2 and high p‑STAT3 levels had the worst survival rate. Moreover, receiver operating characteristic (ROC) curve analysis confirmed that AIM2 was predictive of specific survival in all HSCC patients [area under the curve (AUC)=0.7160]. In conclusion, our data suggested that for HSCC patients, AIM2 and p‑STAT3 expression detected via IHC could serve as a biomarker to predict tumor progression and as an independent prognostic factor.

Notch1 serves as a prognostic factor and regulates metastasis via regulating EGFR expression in hypopharyngeal squamous cell carcinoma.

ObjectiveHypopharyngeal squamous cell carcinoma (HSCC) remains one of the most lethal malignancies in head and neck. Notch1 has been validated to play prominent roles in the occurrence and development of various types of cancer. The aim of this study was to explore the function and underlying mechanism of Notch1 in HSCC.Patients and methodsSeventy-one cancer tissue samples and adjacent noncancerous formalin-fixed paraffin embedded tissue specimens were analyzed by immunohistochemistry. As Notch1 is overexpressed in HSCC, we further questioned whether there was a relationship between Notch1 and the clinicopathological characteristics. After confirming the successful knockdown of Notch1 by siRNA, the migration and invasion after gene knockdown were investigated by Transwell chambers. We then tried to identify YBX1 and EGFR expression using real-time PCR (RT-PCR) and Western blot analyses. To further determine whether the downexpression of EGFR was caused by YBX1 and the overexpression of YBX1 was caused by gene amplification, the expression of EGFR was detected by RT-PCR and Western blot assays.ResultsWe found that the expression of Notch1 and EGFR in HSCC tissues was upregulated compared with those in the adjacent noncancerous tissues. Further clinicopathological characteristics analysis revealed that the expression of Notch1 was positively correlated with distant metastasis (P=0.003) and tumor differentiation (P=0.031). The high expression of Notch1 is an independent prognostic factor for a poor overall survival in patients with HSCC (P=0.015, χ2=10.403). Knocking down of Notch1 significantly inhibits the migration and invasion of FaDu cells in vitro. Mechanistic investigation reveals that Notch1 knockdown is found suppressing the expression of EGFR at transcriptional level. Interestingly, we further found that Notch1 knockdown also decreased the expression of YBX1, which is a transcription factor of EGFR. Moreover, the upregulation of YBX1 reverses the suppression of Notch1 on EGFR. Furthermore, forced overexpression of YBX1 induced the invasion of FaDu cells.ConclusionTaken together, we found a positively cross-linked role of Notch1 signaling in the outcome of HSCC, providing a novel valuable prognostic marker and potential therapeutic target for the treatment of HSCC patients. Notch1 is a core signaling molecule for regulating migration and invasion via interplaying with EGFR in HSCC cells.

Silencing Ras-Related C3 Botulinum Toxin Substrate 1 Inhibits Growth and Migration of Hypopharyngeal Squamous Cell Carcinoma via the P38 Mitogen-Activated Protein Kinase Signaling Pathway.

BackgroundRas-related C3 botulinum toxin substrate 1 (Rac1) is implicated in a variety of cellular functions and is related to tumor growth and metastasis. This study aimed to explore the role of Rac1 in hypopharyngeal squamous cell carcinoma (HSCC).Material/MethodsThe Rac1 expression in HSCC tissues was determined by quantitative real-time polymerase chain reaction and Western blot analysis. The level of Rac1 in HSCC cells was downregulated by a Rac1-specific shRNA. Then, the growth and metastasis of HSCC cells were assessed in vitro by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, flow cytometry, Hoechst staining, and Transwell assay. Moreover, cells transfected with Rac1 shRNA or negative control were injected subcutaneously into the right axilla of mice, and then the effects of Rac1 silencing on the growth of HSCC were also explored in vivo. Additionally, activation of the P38 mitogen-activated protein kinase (MAPK) signaling pathway was assessed by Western blot.ResultsRac1 was highly expressed in HSCC tissues. Silencing Rac1 inhibited the proliferation and cell cycle progress of HSCC cells, and induced their apoptosis. Rac1 silencing also suppressed the migration and invasion of HSCC cells. In vivo study showed that silencing Rac1 suppressed the growth of tumor bodies. Moreover, the P38 MAPK signaling pathway was implicated in the tumor-suppressing effect of Rac1 silencing in vitro and in vivo.ConclusionsSilencing Rac1 suppressed the growth and migration of HSCC through the P38 MAPK signaling pathway. Due to its contribution in HSCC, Rac1 has the potential to become a promising antitumor therapeutic target for HSCC.

FoxM1 overexpression promotes cell proliferation and migration and inhibits apoptosis in hypopharyngeal squamous cell carcinoma resulting in poor clinical prognosis.

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 down-regulation 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.

Novel circular RNA expression profiles reflect progression of patients with hypopharyngeal squamous cell carcinoma.

Circular RNAs (circRNAs), a novel class of endogenous noncoding RNAs, have been shown to have important roles in a number of diseases, including several types of cancers. We hypothesized that circRNAs are involved in the pathogenesis of hypopharyngeal squamous cell carcinoma (HSCC). To test our hypothesis, we initially compared the expression profiles of circRNAs in 4 paired HSCC and adjacent normal tissue samples by using a circRNA microarray. The microarray data showed that 2392 circRNAs, including 1304 upregulated and 1088 downregulated circRNA transcripts, were significantly dysregulated in the HSCC tissues. The 10 most dysregulated circRNAs from the microarray analysis were further validated in another 32 pairs of specimens using quantitative real-time polymerase chain reaction assays. These circRNAs might sponge microRNAs (miRNAs) in predicted circRNA-miRNA-mRNA networks. Bioinformatics analysis was also performed to predict possible pathways in which these networks might be involved. Finally, we analyzed the interaction between validated circRNAs and their potential cancer-related miRNA targets. We are the first to comprehensively delineate the expression profiles of circRNAs in HSCC and to provide potential candidates for future mechanism studies. Our study is potentially of critical significance in uncovering the roles of circRNAs in HSCC.

Caveolin-1 is overexpressed in hypopharyngeal squamous cell carcinoma and correlates with clinical parameters

The present study aimed to identify the role of caveolin-1 (CAV1) in hypopharyngeal squamous cell carcinoma (HSCC) and identify its possible correlation with tumor clinical parameters. Expression of CAV1 was measured using immunohistochemical staining of 66 HSCC samples and 44 samples from morphologically normal tissues adjacent to the carcinomas. Expression of CAV1 in HSCC and paracancerous tissues were 71.2 and 9.5% respectively. Levels of CAV1 expression were significantly associated with tumor differentiation, tumor-node-metastasis stage and lymph nodes metastasis (P<0.05). The present study identified that expression of CAV1 in HSCC is significantly higher than in paracancerous tissues, suggesting that this high expression of CAV1 is associated with tumor invasion and metastasis.

Prognostic significance of claudin-1 and cyclin B1 protein expression in patients with hypopharyngeal squamous cell carcinoma.

Claudin-l and cyclin B1 are abnormally expressed in certain malignancies, but their expression in hypopharyngeal squamous cell carcinoma (HSCC) has not been reported thus far. Studying the expression levels of claudin-1 and cylin B1 in HSCC tissues and their association with clinical stage, pathological grade and prognosis in patients with HSCC may provide a theoretical basis and guide future research on HSCC targeted therapy. The protein expression levels of the above two biomarkers was immunohistochemically detected in 97 HSCC cases and 90 matched adjacent tissue samples. The correlation between the expression levels of claudin-1 and cylin B1 and the patients' clinical parameters was analyzed via Pearson's χ2 test, while survival analysis was performed using a log-rank test. The results of the current study revealed that claudin-1 and cyclin B1 were highly expressed in HSCC tissues, and the expression of claudin-1 was associated with tumor differentiation degree and lymph node metastasis, while cyclin B1 expression was associated with tumor differentiation degree. Furthermore, Kaplan-Meier analysis revealed that claudin-1 expression correlated with survival (P=0.003), and the expression levels of claudin-1 and cyclin B1 were observed to be positively correlated, in patients with HSCC. Cyclin B1 and claudin-1 exhibited an elevated expression in HSCC specimens, thus suggesting their use as tumor markers. Therefore, the joint detection of claudin-1 and cyclin B1 may aid to guide cancer therapy and to determine prognosis in HSCC. Furthermore, claudin-1 may be used as an HSCC-monitoring index, and may serve as a therapeutic target.

AB209630, a long non-coding RNA decreased expression in hypopharyngeal squamous cell carcinoma, influences proliferation, invasion, metastasis, and survival.

Long noncoding RNAs (lncRNAs) are associated with the development, progression, and prognosis of human cancers. However, the clinical significance and biological function of lncRNAs in hypopharyngeal squamous cell carcinoma (HSCC) remain largely unknown. We characterized the novel lncRNA AB209630 in vivo and in vitro. First, using qRT-PCR, we evaluated whether AB209630 levels differ between HSCC tissues/cell lines and adjacent normal tissues/cell lines. We then assessed whether AB209630 expression levels stimulate or inhibit proliferation, invasion, apoptosis, and metastasis in vitro. Finally, we investigated whether AB209630 levels in tumor tissues were associated with survival outcomes. Our results demonstrated that AB209630 levels were markedly lower in HSCC tissues and cells than in normal tissues and cells, and increased expression of AB209630 level significantly inhibited growth, metastasis, and invasion and stimulated apoptosis in vitro. In addition, patients with decreased expression of AB209630 had a significantly poorer prognosis than those with high AB209630 expression. These data suggest that increased expression of AB209630 might either stimulate or inhibit biological activities involved in HSCC development, indicating a potential application of AB209630 in future treatment for this disease. This study suggest that AB209630 functions as a tumor suppressor in HSCC, and its decreased expression may help predict a poor prognostic outcome of HSCC. Our future work will focus on the mechanisms of whether and how AB209630 as a tumor suppressor gene is involved in HSCC development.

MicroR-140-5p suppresses tumor cell migration and invasion by targeting ADAM10-mediated Notch1 signaling pathway in hypopharyngeal squamous cell carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs of approximately 22 nucleotides that negatively regulate gene expression at the post-transcriptional level. Downexpression of miR-140-5p was reported in some human cancers, and combined with a reduction of cell migration and invasion, suggesting that miR-140-5p functions as a tumor suppressor. However, little is known about the expression and function of miR-140-5p in hypopharyngeal squamous cell carcinoma (HSCC). In this research, we found that miR-140-5p was significantly downregulated in HSCC tissues and correlated to tumor classification and lymph node metastasis. Restoration of miR-140-5p suppressed the migration and invasion of FaDu cells, and decreased the protein expression levels of ADAM10. Furthermore, the luciferase reporter assay revealed that miR-140-5p was directly bound to ADAM10 mRNA and knockdown of ADAM10 could inhibit FaDu cell migration and invasion and reduced the protein expression levels of and Notch1 intracellular domain (NICD1). Of note, knockdown of Notch1 could inhibit the migration and invasion of FaDu cells and rescued the effect of miR-140-5p inhibitor in FaDu cells. Taken together, our study demonstrates that miR-140-5p suppresses tumor migration and invasion by inhibiting ADAM10-mediated Notch1 signaling pathway and suggests that miR-140-5p could have potential therapeutic applications in HSCC.

Aberrant GRK6 promoter methylation is associated with poor prognosis in hypopharyngeal squamous cell carcinoma.

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.

Expression of Skp2 and p27kip1 proteins in hypopharyngeal squamous cell carcinoma and its clinical significance.

The aim of the present study was to determine the effect of S-phase kinase-associated protein 2 (Skp2) and cyclin-dependent kinase inhibitor p27kinase-interacting protein 1 (p27kip1) protein expression on the occurrence and development of hypopharyngeal squamous cell carcinoma. The protein expression levels of Skp2 and p27kip1 were detected in 42 hypopharyngeal squamous cell carcinoma and 15 normal hypopharyngeal mucous membrane specimens using the an immunohistochemical PV-9000 two-step method. The expression levels of Skp2 protein were significantly different in hypopharyngeal squamous cell carcinomas and normal hypopharyngeal mucous membranes (61.90 vs. 26.67%; P<0.05). By contrast, the protein expression levels of Skp2 were significantly positively correlated with tumor T stage (rs=0.329, P<0.05) and cervical lymph node metastasis (rs=0.402, P<0.05). Furthermore, the expression levels of p27kip1 protein were significantly different in hypopharyngeal squamous cell carcinomas and normal hypopharyngeal mucous membranes (11.9 vs. 53.33%; P<0.05), while p27kip1 protein expression was significantly negatively correlated with tumor T-stage (rs=-0.351, P<0.05) and cervical lymph node metastasis (rs=-0.371, P<0.05). Notably, a significant negative correlation was observed between the expression levels of Skp2 and p27kip1 proteins in hypopharyngeal squamous cell carcinoma (P<0.05). In addition, abnormal expression levels of Skp2 and p27kip1 proteins were observed in hypopharyngeal squamous cell carcinoma tissues. Thus, Skp2 and p27kip1 proteins may be involved in the development of hypopharyngeal squamous cell carcinoma. The current study proposed that combined detection of Skp2 and p27kip1 may be useful for assessing the characteristics and prognosis of hypopharyngeal squamous cell carcinoma.

MicroRNA-504 inhibits cancer cell proliferation via targeting CDK6 in hypopharyngeal squamous cell carcinoma

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 kinase6 (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.

Significance of the expression of integrin β1, VEGF and MVD in hypopharyngeal squamous cell carcinoma.

This study aimed to determine the expression of integrin β1 and vascular endothelial growth factor (VEGF) and microvascular density (MVD) by CD105 staining in hypopharyngeal squamous cell carcinoma to determine their association with clinicopathologic characteristics, and to determine their role and the effects of their interactions in the development and progression of hypopharyngeal squamous cell carcinomas. The expression of integrin β1 and VEGF and MVD in hypopharyngeal squamous cell carcinomas and normal hypopharyngeal tissues were evaluated using immunohistochemistry. The Image-Pro Plus software was used to determine the mean optical density of the immunohistochemical images. Integrin β1 expression was significantly higher in hypopharyngeal squamous cell carcinoma tissues (78.00%) than in normal hypopharyngeal tissues (35.00%; P = 0.001) and significantly differed across pathologic grades and different T stages, and regarding the presence of cervical lymph node metastasis (P < 0.05). VEGF expression was significantly higher in hypopharyngeal squamous cell carcinoma tissues (74.00%) than in normal hypopharyngeal tissues (30.00%; P = 0.002), VEGF overexpression differed significantly across different pathologic grades and different T stages, and regarding the presence of cervical lymph node metastasis (P < 0.05). The MVD count was significantly higher in hypopharyngeal squamous cell carcinoma tissues (37.10 ± 5.95) than in normal hypopharyngeal tissues (8.70 ± 3.34; P = 0.000). MVD differed significantly across different pathologic grades and different T stages, and regarding the presence of cervical lymph node metastasis (P < 0.05). The expression of integrin β1 and VEGF and the MVD count exhibited no significant differences in terms of age, gender, history of smoking, and clinical stages (P > 0.05). VEGF expression was positively associated with the MVD count of hypopharyngeal squamous cell carcinomas (r = 0.582, P = 0.000); however, integrin β1 was not associated with VEGF or MVD (P > 0.05). Integrin β1 and VEGF are overexpressed and MVD increased in hypopharyngeal squamous cell carcinomas. VEGF is positively correlated with MVD.

Abstract 2094: MicroRNA expression signatures in hypopharyngeal squamous cell carcinoma (HSCC): miR-489 inhibits cell proliferation by targeting PTPN11

Abstract Head and neck squamous cell carcinoma (HNSCC) affects the oral cavity, oropharynx, larynx, and hypopharynx, and is the sixth most common cancer accounting for over 500,000 new cases annually, worldwide. Hypopharyngeal squamous cell carcinomas (HSCC) are an aggressive malignancy associated with one of the worst prognoses within HNSCC. Survival rates of patients with HSCC have not improved despite recent advances in various treatment modalities, including surgery, radiotherapy and chemotherapy. Understanding of the molecular oncogenic pathways underlying HSCC would be helpful to improve diagnosis, therapy, and prevention of the disease. MicroRNAs (miRNA) are a class of naturally occurring, small, non-coding RNA that can control gene expression by targeting mRNA molecules for translational repression or cleavage. Mature miRNAs originate from pre-miRNAs that consist of 70- to 100-nucleotide hairpins. The precursors are cleaved by cytoplasmic RNase III Dicer to give around 22-nucleotide miRNA duplexes. One strand of the short-lived duplex is then degraded, whereas the other strand serves as mature miRNA. Mature miRNAs bind through partial sequence homology to the 3’-untranslated regions (3’-UTR) of target messenger RNAs, and block either translation or mRNA degradation. In cancer research, miRNAs have recently been found to be aberrantly expressed in several types of human cancer, and it appears that some miRNAs can function as oncogenes or tumor suppressors. Dysregulated miRNAs may play a role in carcinogenesis or tumor progression by altering normal gene expression patterns. The aim of this study was to identify tumor suppressive miRNAs based on miRNA expression signatures of HSCC tissues and to predict biological target genes. Expression levels of 365 human mature miRNAs were screened using the stem-loop real-time quantitative PCR method. We identified 11 up-regulated and 31 down-regulated mature miRNAs based on miRNA expression signatures. Gain-of-function analysis of down-regulated miRNAs revealed that five miRNAs (miR-489, miR-126, miR-195, miR-1 and miR-497) inhibited cell growth in cancer cell lines, with miR-489 inhibiting cell growth in all cancer cell lines examined. We identified PTPN11, a cytoplasmic protein tyrosine phosphatase that contains two Scr homology domains, as a miR-489 target gene using genome-wide gene expression analysis. miR-489-transfected cells showed reduced PTPN11 protein and mRNA expression levels. In addition, knockdown of PTPN11 expression inhibited cell growth, which suggested that PTPN11 functioned as an oncogene. Tumor suppressive miRNAs and target oncogenes may provide new insights into the mechanisms in cancer. Our findings have therapeutic implications and may be exploited for future HSCC treatments. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2094.