title: Downregulated Chibby in laryngeal squamous cell carcinoma with increased expression in laryngeal carcinoma Hep-2 cells.
abstract: Chibby (Cby) inhibits Wnt/β-catenin-mediated transcriptional activation by competing with Lef-1 (the transcription factor and target of β-catenin) to bind to β-catenin. This suggests that Cby could be a tumor suppressor protein. In the present study, we examined Cby expression in laryngeal squamous cell carcinoma (LSCC) and its function and mechanism in laryngeal carcinoma cell lines. Cby expression levels were investigated by immunohistochemistry in a panel of 36 LSCC patient cases. The expression of β-catenin, c-myc and cyclin D1 in Hep-2 were determined through RT-PCR and western blot analysis. Activity of Wnt/β-catenin signaling pathway after overexpression of Cby was measured by TCF/LEF luciferase reporter gene assay. Proliferation, clone forming ability, cell cycle distribution and cell apoptosis of Hep-2 cells were detected by MTT assay, plate colony forming assay, flow cytometry and TUNEL assay, respectively. This study showed that expression of Cby protein was strongly downregulated in LSCC tumor tissues in comparison to normal laryngeal mucosa samples. No significant correlation was found between the expression of Cby in tumor tissue and gender, age, clinical stage and tumor differentiation of laryngeal cancer patients. When Cby was overexpressed in Hep-2 cells, the expression of cyclin D1 was reduced and β-catenin activity was inhibited. Proliferation and plate colony forming assays revealed a significant inhibitory effect of Cby on growth and colony formation ability of Hep-2 cells after Cby overexpression in comparison to control and mock-infected cells. In addition, we also found that upregulated expression of Cby resulted in accumulation of numbers of cells in G0/G1 phase with concomitant decrease in S phase by cell cycle assay. TUNEL staining demonstrated that, compared with the control group, the rate of apoptosis in the plv-cs2.0-Cby group was significantly increased. Taken together, downregulation of Cby was observed in LSCC, but with no significant correlation to the clinicopathological features of LSCC patients. Overexpression of Cby effectively suppressed laryngeal carcinoma cell growth and promoted its apoptosis. A better understanding of the mechanisms of Cby gene activation in LSCC could provide potential novel therapeutic targets for human laryngeal carcinoma.
authors.affiliation: Department of Otolaryngology, The First Hospital Affiliated to Huzhou University Medical College, Huzhou, Zhejiang 313000, P.R. China.
authors.forename: Jue
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Otolaryngology, The First Hospital Affiliated to Huzhou University Medical College, Huzhou, Zhejiang 313000, P.R. China.
authors.forename: Gang
authors.initials: G
authors.lastname: Ren
authors.affiliation: Department of Otolaryngology, the 174th Hospital of PLA, Xiamen, Fujian 361003, P.R. China.
authors.forename: De-An
authors.initials: DA
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Bo-An
authors.initials: BA
authors.lastname: Li
authors.affiliation: Department of Otolaryngology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China.
authors.forename: Cheng-Fu
authors.initials: CF
authors.lastname: Cai
authors.affiliation: Department of Otolaryngology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Otolaryngology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China.
authors.forename: Xian-Yang
authors.initials: XY
authors.lastname: Luo
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D019938:Cyclin D1 / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006801:Humans; D007822:Laryngeal Neoplasms / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D060449:Wnt Signaling Pathway
chemical_list: C473750:CBY1 protein, human; C530104:CCND1 protein, human; D002352:Carrier Proteins; D009687:Nuclear Proteins; D019938:Cyclin D1