KDM4A, KDM4B and KDM4C in non-small cell lung cancer

KDM4A, KDM4B and KDM4D are lysine demethylases which demethylate H3 at lysine K9 and K36 sites, additionally KDM4D also the H1.4 linker histone at K26 lysine. Lysine methylation changes can repress or induce gene expression at specific sites thus influencing cellular functions. We analysed the immunohistochemical expression of KDM4A, KDM4B and KDM4D in a clinical material of 188 patients with lung carcinomas. There were 132 (70%) squamous cell carcinomas, 53 (28%) adenocarcinomas and 3 (2%) large cell carcinomas in the study. Additionally, the trimethylated state of chromatin was detected with an antibody to trimethylated H3K9 residue. Nuclear KDM4A and KDM4D were associated with the presence of lymph node metastases in tumors. Cytoplasmic KDM4A was associated with poor survival of the patients (P = 0.015) and with a shorter recurrence free interval (P = 0.028). KDM4A and KDM4D appear to have a significant role in the metastatic spread of lung carcinomas. The findings are also in line with their proposed involvement in mechanisms associated with cell proliferation, apoptosis and DNA repair.

EZH2, a potential regulator of dental pulp inflammation and regeneration

INTRODUCTION

Dental pulp has limited capability to regenerate, which happens in the early stage of pulpitis. An ambiguous relationship exists; inflammation may impair or support pulp regeneration. Epigenetics, which is involved in cell proliferation and inflammation, could regulate human dental pulp cell (HDPCs) regeneration. The aim of this study was to determine the role of the epigenetic mark, enhancer of zeste homolog 2 (EZH2), in the inflammation, proliferation, and regeneration of dental pulp. We used trimethylated histone H3 lysine 27(H3K27me3) and its lysine demethylase 6B (KDM6B) to monitor functional effects of altered EZH2 levels.

METHODS

We detected epigenetic marks (EZH2, H3K27me3, and KDM6B) in pulp tissue by immunohistochemistry and immunofluorescence. EZH2 levels in HDPCs in inflammatory responses or differentiation were analyzed by quantitative polymerase chain reaction and Western blot. Quantitative polymerase chain reaction was used to assess the effects of EZH2 inhibition on interleukins in HDPCs upon tumor necrosis factor alpha stimulation. Cell proliferation was tested by cell counting kit-8, cell cycle, and apoptosis analysis. HDPC differentiation was investigated by quantitative polymerase chain reaction, alkaline phosphatase activity, and oil red O staining.

RESULTS

EZH2 and H3K27me3 were decreased, whereas KDM6B was increased in infected pulp tissue and cells, which were similar to HDPC differentiation. EZH2 inhibition suppressed IL-1b, IL-6, and IL-8 messenger RNA (mRNA) in HDPCs upon inflammatory stimuli and impeded HDPC proliferation by decreasing cell number, arresting cell cycle, and increasing apoptosis. Suppressed EZH2 impaired adipogenesis, peroxisome proliferator-activated receptor r (PPAR-r), and CCAAT-enhancer binding protein a (CEBP/a) mRNA in adipogenic induction while enhancing alkaline phosphatase activity, Osx, and bone sialoprotein (BSP) mRNA in mineralization induction of HDPCs.

CONCLUSIONS

EZH2 inhibited HDPC osteogenic differentiation while enhancing inflammatory response and proliferation, suggesting its role in pulp inflammation, proliferation, and regeneration.

KDM4C (GASC1) lysine demethylase is associated with mitotic chromatin and regulates chromosome segregation during mitosis

Various types of human cancers exhibit amplification or deletion of KDM4A-D members, which selectively demethylate H3K9 and H3K36, thus implicating their activity in promoting carcinogenesis. On this basis, it was hypothesized that dysregulated expression of KDM4A-D family promotes chromosomal instabilities by largely unknown mechanisms. Here, we show that unlike KDM4A-B, KDM4C is associated with chromatin during mitosis. This association is accompanied by a decrease in the mitotic levels of H3K9me3. We also show that the C-terminal region, containing the Tudor domains of KDM4C, is essential for its association with mitotic chromatin. More specifically, we show that R919 residue on the proximal Tudor domain of KDM4C is critical for its association with chromatin during mitosis. Interestingly, we demonstrate that depletion or overexpression of KDM4C, but not KDM4B, leads to over 3-fold increase in the frequency of abnormal mitotic cells showing either misaligned chromosomes at metaphase, anaphase-telophase lagging chromosomes or anaphase-telophase bridges. Furthermore, overexpression of KDM4C demethylase-dead mutant has no detectable effect on mitotic chromosome segregation. Altogether, our findings implicate KDM4C demethylase activity in regulating the fidelity of mitotic chromosome segregation by a yet unknown mechanism.