14P - Histone H2AX phosphorylation increases apoptosis of lung cancer cells by miR-3196/PUMA pathway

Date 07 May 2017
Event ELCC 2017
Session Poster Display Session
Topics Lung and other Thoracic Tumours
Pathology/Molecular Biology
Presenter Chengrong Lu
Citation Annals of Oncology (2017) 28 (suppl_2): ii1-ii5. 10.1093/annonc/mdx090
Authors C. Lu, C. Xu, L. Zhang, L. Duan
  • Aviation Medicine Research Laboratory, Air Force General Hospital (PLA), 100142 - Beijing/CN

Abstract

Background

Increasing amount of studies indicate that histone H2AX acts as a novel tumor suppressor, but the detailed mechanism of apoptosis in tumor cells regulated by H2AX remains elusive.

Methods

Microarray assay was performed to analyze differentially expressed apoptosis-related miRNAs regulated by H2AX in lung cancer cells. The flow cytometry (FCM) assay was performed for detection of apoptosis. Quantitative RT-PCR (qRT-PCR) was used to detect miR-3196 expression. Chromatin immunoprecipitation (ChIP) together with qRT-PCR was used to evaluate the binding of gamma-H2AX and RNA polymerase II to the miR-3196 promoter, and H3K27 trimethylation level in the promoter region of miR-3196. H2AX, BIRC7, PUMA and β-actin protein levels were determined by western blotting. The miR-3196 binding to PUMA mRNA at the 3′-UTR and miR-3196 promoter activity were evaluated by luciferase assay. Lipofectamine 2000 was used for transfection of vectors and miR-3196 mimics or miR-3196 inhibitor.

Results

The data from microarray assay demonstrated that histone H2AX was involved in regulation of miRNAs expression during lung cancer cell apoptosis. H2AX knockdown affected the expression of 16 miRNAs, resulting in the downregulation of 1 and the upregulation of 15 miRNAs. Among the upregulated miRNAs, miR-3196 was identified as a target of H2AX and shown to inhibit apoptosis in lung cancer cells by targeting p53 upregulated modulator of apoptosis (PUMA). Phosphorylated H2AX (gamma-H2AX) was shown to bind to the promoter of miR-3196 and regulate its expression. In addition, H2AX phosphorylation increased H3K27 trimethylation in the promoter region of miR-3196 and inhibited the binding of RNA polymerase II to the promoter of miR-3196, leading to the inhibition of miR-3196 transcription. Taken together, these results indicated that miR-3196 is inhibited by H2AX phosphorylation and attenuates lung cancer cell apoptosis by downregulating PUMA.

Conclusions

Histone H2AX phosphorylation increases apoptosis of lung cancer cells via the miR-3196/PUMA pathway.

Clinical trial identification

This study does not contain clinical trial.

Legal entity responsible for the study

Air Force General Hospital (PLA)

Funding

National Natural Science Foundation of China

Disclosure

All authors have declared no conflicts of interest.