ABSTRACT
Enhancer of Zeste Homolog 2(EZH2), which can change chromatin structure by tri-methylation of the 27th lysine of H3 in nucleosome histone (H3K27me3), is involved in different types of cancers. However, the role and mechanism underlying aberrant EZH2 expression in laryngeal squamous cells carcinoma (LSCC) remain unclear. In the present study, we found that down-regulation of EZH2 and H3K27me3 in LSCC cells (Hep-2 and SCC10A) resulted in an mesenchymal-epithelial transition(MET) like cell morphology and lower invasion in vitro, weakened tumor growth, intrahepatic and pulmonary metastasis in vivo. Furthermore, EZH2 promoted the epithelial-mesenchymal transition(EMT) process through down-regulation of Ca2+ dependent cell adhesion molecule E (E-cadherin) and up-regulation of H3K27me3 in vitro and in vivo. Moreover, E-cadherin was transcriptionally induced upon stable knockdown of EZH2, and quantitative chromatin immunoprecipitation(qChIP) analysis confirmed the depletion of H3K27me3 enrichment on E-cadherin promoter upon EZH2 knockdown in Hep-2 and SCC10A cells. In addition, the expression of EZH2 was positively correlated with that of H3K27me3 and both of them were inversely correlated with E-cadherin expression in human LSCC tissues. In summary, this study indicated that EZH2 promoted invasion and metastasis of LSCC via EMT through H3K27me3.
Subject(s)
Carcinoma, Squamous Cell/metabolism , Enhancer of Zeste Homolog 2 Protein/metabolism , Gene Expression Regulation, Neoplastic , Histones/metabolism , Laryngeal Neoplasms/metabolism , Animals , Antigens, CD , Cadherins/metabolism , Calcium/metabolism , Cell Line, Tumor , Epithelial-Mesenchymal Transition , Gene Knockdown Techniques , Humans , Immunohistochemistry , Lymphatic Metastasis , Mice , Mice, Nude , Neoplasm Invasiveness , Neoplasm Metastasis , Promoter Regions, Genetic , Real-Time Polymerase Chain ReactionABSTRACT
microRNA-129-5p may have a relationship with laryngeal squamous cell carcinoma (LSCC), but the expression and function of miRNA-129-5p are not fully understood. This study was performed to investigate the expression and function of miRNA-129-5p in LSCC and its effects on STAT3. HBE and Hep-2 cells were cultured and analyzed by western blotting and real-time PCR. miR-129-5p expression was detected by real-time PCR. Hep-2 cells were transfected with a miR-129-5p expression vector. Cell proliferation, invasion, migration, cell cycle, and apoptosis assays were used to determine the role of miRNA-129-5p in the growth, invasion, and migration of LSCC cells and to determine the importance of STAT3 in these effects. STAT3 mRNA expression in Hep-2 cells was significantly higher than that in HBE cells (P < 0.05). miR-129-5p expression detected by real-time PCR showed that it was expressed at a lower level in Hep-2 cells than in HBE cells (P < 0.05). Compared with the control cells, the transfected cells showed lower STAT3 mRNA expression. For up to 7 days in culture, the transfected cells showed lower proliferation than the control cells (P < 0.05). After 24 h in culture, the apoptosis rate in miR-129-5p-transfected cells was 3.48 ± 0.38 %, while the rate in control cells was 0.92 ± 0.09 % (P = 0.0028), but the statistical significance was lost after 72 h in culture (P = 0.3180). The invasion and migration of the cells were inhibited after 24 and 72 h in culture when the miR-129-5p expression in Hep-2 cells was upregulated (P = 0.0037 and 0.00383, respectively), while there was no statistically significant difference at 48 h (P = 0.0712). STAT3 expression could be suppressed by the upregulation of miR-129-5p expression. Both the proliferation and migration of tumor cells were suppressed when the level of STAT3 expression was decreased. The apoptosis rate of tumor cells was also increased. Based on these data, we suggest that miR-129-5p may directly inhibit STAT3 expression and play an important role in the development of LSCC.