Abstract
Genetic and epigenetic alterations influence gene expression and lead to aberrant gene functions in the progression of cancer. Epigenetic changes in chromatin involve functional alteration through post-translational modifications on histone proteins, particularly histone 3 (H3) and histone 4 (H4). Histone lysine demethylases (KDMs) in couple with histone methyltransferase regulates the histone methyl marks and have been indicated in carcinogenesis. The jumonji-only histone demethylase KDM8 (or JMJD5), an H3K36me2 demethylase has been found to be overexpressed in breast cancer and regulates cell cycle. Whether KDM8 regulates one or more aspects of the malignant process (dysregulated potential of replication, tissue invasion and metastasis) remains elusive. Here, we are interested to investigate the tumor metastasis phenotype owing to its severe clinical outcome into the advanced cancer stage. Understanding how an epithelial phenotype transforms into a mesenchymal one, referred as epithelial-mesenchymal transition (EMT), is important to unravel the central mechanisms that induces invasion and metastasis of tumor. To this aim, KDM8-overexpressing MCF-7 and MDA-MB-231 cells were chosen in this study. KDM8 was knockdown in these cells (MCF7-KDM8-kd and 231-KDM8-kd) via short-hairpin RNA. Analysis of the parental and KDM8-kd cells showed a significant decrease in cell proliferation and migration of both KDM8-kd cell lines. EMT markers in KDM8-kd breast cancer cell lines were also investigated by Real Time-PCR and Western blotting analysis. We found a much lower expression of N-cadherin in 231-KDM8-kd cells and a higher level of E-cadherin in MCF7-KDM8-kd cells. A master EMT regulator, Twist expression is significantly reduced in 231-KDM8-kd cells. These results together suggest that KDM8 is involved in regulating the Twist signaling pathway that promotes metastasis.