The histone variant H2A.X is a regulator of the epithelial–mesenchymal transition

Abstract

The epithelial–mesenchymal transition (EMT), considered essential for metastatic cancer, has been a focus of much research, but important questions remain. Here, we show that silencing or removing H2A.X, a histone H2A variant involved in cellular DNA repair and robust growth, induces mesenchymal-like characteristics including activation of EMT transcription factors, Slug and ZEB1, in HCT116 human colon cancer cells. Ectopic H2A.X re-expression partially reverses these changes, as does silencing Slug and ZEB1. In an experimental metastasis model, the HCT116 parental and H2A.X-null cells exhibit a similar metastatic behaviour, but the cells with re-expressed H2A.X are substantially more metastatic. We surmise that H2A.X re-expression leads to partial EMT reversal and increases robustness in the HCT116 cells, permitting them to both form tumours and to metastasize. In a human adenocarcinoma panel, H2A.X levels correlate inversely with Slug and ZEB1 levels. Together, these results point to H2A.X as a regulator of EMT.

Twist1 and Slug mediate H2AX-regulated epithelial-mesenchymal transition in breast cells

“…4,[18][19][20][21] These observations indicate that H2A.X loss leads to the activation of EMT program in breast cells. As many of the movement-associated genes observed in MCF10A cells were also found to regulate EMT, migration and invasion in human colon cancer cell line HCT116, 12 our data suggest the existence of H2A.X-driven EMT signature shared by breast and colon cancer cells. We then analyzed the movement-associated genes shared between MCF10A and HCT116 cells.…”

“…4). These genes seem to be conserved in colon cancer cells, 12 thus suggesting that the role of H2A.X in EMT is more broad. EMT occurs in embryogenesis and organ development, in tissue regeneration and in metastasis during cancer progression.…”

“…12 In the present study, we asked whether epithelial cells from a different origin, breast tissue, might also exhibit EMT following H2A.X removal. Utilizing normal and H2A.X-null MCF10A cell lines, we observed that the H2A.X deletion correlated with elevated levels of migration and invasion, as substantiated by wound healing and transwell invasion assays respectively (Fig.…”

“…In our recent study, we reported that Slug (Snail2) and Zeb1 concomittantly regulate H2A.X loss-induced EMT in human colon cancer cells. 12 As none of these EMT transcription factors was found in our micro array data sets from MCF10A cells, we accessed the transcript levels of the main EMT transcription factors including Twist1, Snail1, Snail2 (Slug) and Zeb1 using real time PCR assay. Our data indicated that in contrast to HCT116 cells, 12 Twist1 was found overexpressed in H2A.X-deficient MCF10A cells (Fig.…”

“…Reverse transcription and Real-time PCR were performed as previously described. 12 Oligonucleotides were purchased from Life Technologies and their sequences are available on demand.…”