Abstract
The aim of the present study was to explore mechanisms underlying the effects of down-regulating β-catenin expression on esophageal carcinoma (EC) cells. Cell cycle distribution and apoptosis were determined using flow cytometry and annexin V apoptosis assay, respectively. Transmission electron microscopy (TEM) was used to examine changes in ultrastructure, while expression of cyclin D1 protein and mRNA was detected by western blot and real-time PCR. Proliferating cell nuclear antigen (PCNA) and extracellular signal-regulated kinase (ERK) 1/2 were evaluated by Western blot analysis. PCNA labeling index (LI) was determined by immunocytochemistry. Compared with pGen-3-con transfected and Eca-109 cells, the percentage of G0/G1-phase pGen-3-CTNNB1 transfected cells was obviously increased (P<0.05), with no significant difference among the three groups with regard to apoptosis (P>0.05). pGen-3-CTNNB1 transfected cells exhibited obvious decrease in cyclin D1 mRNA and protein expression (P<0.05) and the ultrastructure of Eca-109 cells underwent a significant change after being transfected with pGen-3-CTNNB1, suggesting that down-regulating β-catenin expression can promote the differentiation and maturation. The expression of PCNA and the ERKI/2 phosphorylation state were also down-regulated in pGen-3-CTNNB1 transfected cells (P<0.05). At the same time, the PCNA labeling index was decreased accordingly (P<0.05). Inhibition of EC Eca-109 cellproliferation by down-regulating β-catenin expression could improve cell ultrastructure by mediating blockade in G0/G1 through inhibiting cyclin D1, PCNA and the MAPK pathway (p-ERK1/2).
Highlights
Esophageal carcinoma (EC) is prevalent in some regions of the world, and occurs at a very high frequency in certain parts of China and the mortality rate ranked the fourth among cancer-related death (Zou et al, 2002; Jemal et al, 2011)
Though great improvement has been achieved in this domain, the current knowledge of the components of Wnt/ß-catenin pathway is still not sufficient to fully explain many aspects of ß-catenin function in Esophageal squamous cell carcinoma (ESCC), and it is still unclear what mechanisms and molecules are involved in the suppression of proliferation and growth of esophageal carcinoma (EC) cells mediated by shRNA against ß-catenin
MTT, clone formation assay, and xenograft tumor model were employed to investigate the impact of down-regulating ß-catenin expression on EC Eca-109 cells growth, and results indicated that knocking down ß-catenin expression might inhibit cell proliferation (Wang et al, 2009), but the exact mechanism remained unclear
Summary
Esophageal carcinoma (EC) is prevalent in some regions of the world, and occurs at a very high frequency in certain parts of China and the mortality rate ranked the fourth among cancer-related death (Zou et al, 2002; Jemal et al, 2011). The previous studies have indicated that ß-catenin functioned as an oncogene in the cancerization process of ESCC, and accumulation of ß-catenin in cytoplasm and nucleus was frequent events during the carcinogenesis of the squamous epithelium of the esophagus (Kimura et al, 1999; de Castro et al, 2000; Zhou et al, 2002). Studies by us and other researchers have indicated that silencing of β-catenin gene could inhibite the proliferation and growth of human EC Eca-109 cells in vitro and in nude mice (Veeramachaneni et al, 2004; Wang et al, 2009), but the exact mechanisms remained unclear. Though great improvement has been achieved in this domain, the current knowledge of the components of Wnt/ß-catenin pathway is still not sufficient to fully explain many aspects of ß-catenin function in ESCC, and it is still unclear what mechanisms and molecules are involved in the suppression of proliferation and growth of EC cells mediated by shRNA against ß-catenin
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