Analysis of H3K27me3 expression and DNA methylation at CCGG sites in smoking and non-smoking patients with non-small cell lung cancer and their clinical significance

Abstract

Smoking frequently leads to epigenetic alterations, including DNA methylation and histone modifications. The effect that smoking has on the DNA methylation levels at CCGG sites, the expression of trimethylation of histone H3 at lysine 27 (H3K27me3) and enhancer of zeste homolog 2 (EZH2), and their interactions in patients with non-small cell lung cancer (NSCLC) were analyzed. There were a total of 42 patients with NSCLC, 22 with adenocarcinomas and 20 with squamous cell carcinomas enrolled in the present study. Expression of H3K27me3, EZH2 and proliferating cellular nuclear antigen (PCNA) were immunohistochemically detected. DNA methylation at CCGG sites was evaluated via histoendonuclease-linked detection of DNA methylation sites. The apoptotic index of cancerous tissues obtained from patients of different smoking statuses was evaluated via the terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling method. The association with clinicopathological data was calculated relative to different smoking statuses. Compared with the non-smokers, smokers with NSCLC exhibited a significantly lower apoptotic index (P<0.05), and frequently had a lower level of DNA methylation at CCGG sites, lower H3K27me3 expression and a higher EZH2 expression (P<0.05). DNA methylation levels at CCGG sites were negatively correlated to the Brinkman index (P=0.017). Furthermore, there was a parallel association between the H3K27me3 and EZH2 expression levels in the majority of smokers, whereas in the majority of non-smokers, there was a diverging association (P=0.015). There was a diverging association between the PCNA and EZH2 expression levels in the majority of smokers; however, in the majority of non-smokers, there was a parallel association (P=0.048). In addition, the association between the CCGG methylation ratio and immunohistochemical expression of H3K27me3 was a parallel association in the majority of smokers, while in the majority of non-smokers there was a diverging association (P=0.049). Conclusively, patients with NSCLC and different smoking statuses exhibit different epigenetic characteristics. Additionally, DNA methylation levels at the CCGG sites may have the ability to determine associations between the expression levels of H3K27me3, EZH2 and PCNA.

RUNX3/H3K27me3 Co-Expression Defines a Better Prognosis in Surgically Resected Stage I and Postoperative Chemotherapy-Naive Non-Small-Cell Lung Cancer

“…Calculated staining score of immunopositive cells and cutoff value determination were mentioned in our previous studies [ 24 , 25 ]. Expression of H3K27me3 in cancerous samples was categorized into low (IHC score ≤4) and high (IHC score >4) subgroups.…”

“…Although loss of RUNX3 expression is prevailing in human solid malignancies, the role of its association in pathogenesis of respiratory malignancies still requires further elucidation. Our previous studies firstly found that NSCLC patients with higher trimethylated histone H3 at lysine 27 (H3K27me3) level demonstrated a lower probability of postoperative local relapse and determined loss of H3K27me3 expression as an independent risk factor [ 24 , 25 ], and secondly found that NSCLC patients with higher RUNX3 level demonstrated a lower likelihood of postoperative distant metastasis, and the loss of RUNX3 expression predicted worst outcome and shorter overall survival (OS) [ 26 ]. In light of both local relapse and distant metastasis contributing to worse outcome in the postoperative setting and the epigenetic regulation that histone modification might have on oncogenes and TSGs, we thus hypothesized that assessment of H3K27me3/RUNX3 co-expression might probably play some role in predicting the surgical outcome of NSCLC patients after radical resection.…”

Loss of H3K27 methylation identifies poor outcomes in adult-onset acute leukemia

“…Patient number is very limited, but it is noteworthy that two out of three patients who were resistant against TKI were prior smokers compared to none of the 8 responders. In patients with non-small cell lung cancer, smokers have been identified with lower H3K27me3 protein expression compared to non-smokers [ 47 ]. Furthermore, cigarette smoke has already been proposed to accelerate progression of FLT3-ITD AML by altering DNA methylation [ 48 ].…”

Silencing of long noncoding RNA PVT1 inhibits podocyte damage and apoptosis in diabetic nephropathy by upregulating FOXA1

“…A functional study has reported that EZH2 usually works as an inhibitor of cancer suppressor genes and that lncRNAs can regulate the growth and metastasis of tumor cells by binding to EZH2 9 . Histone 3 lysine 27 trimethylation (H3K27me3) is a transcription-suppressive histone modification whose methylation is achieved via EZH2 10 . One study suggested that the downregulation of EZH2 can decrease H3K27me3 in teratoma-forming cells 11 .…”