RNF8 promotes epithelial-mesenchymal transition of breast cancer cells

Abstract

BackgroundEpithelial-mesenchymal transition (EMT) is a crucial step for solid tumor progression and plays an important role in cancer invasion and metastasis. RNF8 is an ubiquitin E3 ligase with RING domain, and plays essential roles in DNA damage response and cell cycle regulation. However the role of RNF8 in the pathogenesis of breast cancer is still unclear.MethodsThe expression of RNF8 was examined in different types of breast cell lines by Western Blotting. EMT associated markers were examined by Immunofluorescence and Western Blotting in MCF-7 when RNF8 was ectopically overexpressed, or in MDA-MB-231 when RNF8 was depleted. Transwell and wound healing assays were performed to assess the effect of RNF8 on cell mobility. The xenograft model was done with nude mice to investigate the role of RNF8 in tumor metastasis in vivo. Breast tissue arrays were used to examine the expression of RNF8 by immunohistochemistry. Kaplan-Meier survival analysis for the relationship between survival time and RNF8 signature in breast cancer was done with an online tool (http://kmplot.com/analysis/).ResultsRNF8 is overexpressed in highly metastatic breast cancer cell lines. Overexpression of RNF8 in MCF-7 significantly promoted EMT phenotypes and facilitated cell migration. On the contrary, silencing of RNF8 in MDA-MB-231 induced MET phenotypes and inhibited cell migration. Furthermore, we proved that these metastatic behavior promoting effects of RNF8 in breast cancer was associated with the inactivation of GSK-3β and activation of β-catenin signaling. With nude mice xenograft model, we found that shRNA mediated-downregulation of RNF8 reduced tumor metastasis in vivo. In addition, we found that RNF8 expression was higher in malignant breast cancer than that of the paired normal breast tissues, and was positively correlated with lymph node metastases and poor survival time.ConclusionsRNF8 induces EMT in the breast cancer cells and promotes breast cancer metastasis, suggesting that RNF8 could be used as a potential therapeutic target for the prevention and treatment of breast cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0363-6) contains supplementary material, which is available to authorized users.

Silencing of Prrx2 Inhibits the Invasion and Metastasis of Breast Cancer both In Vitro and In Vivo by Reversing Epithelial-Mesenchymal Transition

“…EMT plays an important role in the differentiation of tissues and organs and in the formation of the body plan, as well as contributes to cancer progression and other diseases [21, 22]. In the current study, we found that Prrx2 may participate in the EMT process, which is supported by the following evidence.…”

The Functions of DNA Damage Factor RNF8 in the Pathogenesis and Progression of Cancer

“…RNF8 is a newly identified coactivator of ERα [10]. The expression of RNF8 was found to be higher in malignant breast cancer tissues compared with normal tissues and was strongly correlated to lymph node metastases and poor survival [82]. The increased level of RNF8 in breast cancer samples was positively correlated with ERα expression.…”

“…The inhibition of GSK3β causes the accumulation and nuclear translocation of β-catenin, which activates EMT-related gene transcription [81]. Overexpression of RNF8 in MCF-7 cells promoted the phosphorylation of GSK3β and further inhibited the activity of GSK3β [82]. The phosphorylation of β-catenin decreased and its protein level increased in RNF8 overexpressed cells, while phosphorylated β-catenin increased and its expression decreased in RNF8 silenced cells.…”

“…When the telomere was already uncapped by deletion of TRF2, the E3 ligase activity of RNF8 in promoting H2A ubiquitination helped to induce C-NHEJ and further caused genomic instability [46]. Furthermore, expression of RNF8 was found to be higher in breast cancer than in normal tissues and was correlated to poor prognosis [82]. RNF8 activated the β-catenin pathway via its E3 ligase activity and promoted EMT phenotype of breast cancer cell [82].…”

Two-faced activity of RNF8: What “twists” it from a genome guardian to a cancer facilitator?

“…A recent study conducted by Shao and colleagues supports our findings by showing that RNF8 is upregulated in malignant breast cancer cells and that overexpressed RNF8 can promote EMT in cell-based experiments and a nude mouse xenograft model. 10 Although DSB-associated RNF8 was known to be a guardian of the genome, we have revealed a novel role for DSB-dissociated RNF8 in cancer metastasis and chemoresistance (Fig. 1).…”