Breast cancer is the most frequent cancer among women worldwide. Biomarkers for early detection and prognosis of these patients are needed. We hypothesized that deafness, autosomal dominant 5 (DFNA5) may be a valuable biomarker, based upon strong indications for its role as tumor suppressor gene and its function in regulated cell death. In this study, we aimed to analyze DFNA5 methylation and expression in the largest breast cancer cohort to date using publicly available data from TCGA, in order to further unravel the role of DFNA5 as detection and/or prognostic marker in breast cancer. We analyzed Infinium HumanMethylation450k data, covering 22 different CpGs in the DFNA5 gene (668 breast adenocarcinomas and 85 normal breast samples) and DFNA5 expression (Agilent 244K Custom Gene Expression: 476 breast adenocarcinomas and 56 normal breast samples; RNA-sequencing: 666 breast adenocarcinomas and 71 normal breast samples). DFNA5 methylation and expression were significantly different between breast cancer and normal breast samples. Overall, breast cancer samples showed higher DFNA5 methylation in the putative gene promoter compared to normal breast samples, whereas in the gene body and upstream of the putative gene promoter, the opposite is true. Furthermore, DFNA5 methylation, in 10 out of 22 CpGs, and expression were significantly higher in lobular compared to ductal breast cancers. An important result of this study was the identification of a combination of one CpG in the gene promoter (CpG07504598) and one CpG in the gene body (CpG12922093) of DFNA5, which was able to discriminate between breast cancer and normal breast samples (AUC = 0.93). This model was externally validated in three independent datasets. Moreover, we showed that estrogen receptor state is associated with DFNA5 methylation and expression. Finally, we were able to find a significant effect of DFNA5 gene body methylation on a 5-year overall survival time. We conclude that DFNA5 methylation shows strong potential as detection and prognostic biomarker for breast cancer.

DFNA5 promoter methylation a marker for breast tumorigenesis DFNA5 promoter methylation a marker for breast tumorigenesis

Gasdermin E (GSDME), also known as deafness autosomal dominant 5 (DFNA5) and previously identified to be an inducer of regulated cell death, is frequently epigenetically inactivated in different cancer types, suggesting that GSDME is a tumor suppressor gene. In this study, we aimed to evaluate the tumor-suppressive effects of GSDME in two intestinal cancer mouse models. To mimic the silencing of GSDME by methylation as observed in human cancers, a Gsdme knockout (KO) mouse was developed. The effect of GSDME on tumorigenesis was studied both in a chemically induced and in a genetic intestinal cancer mouse model, as strong evidence shows that GSDME plays a role in human colorectal cancer and representative mouse models for intestinal cancer are available. Azoxymethane (AOM) was used to induce colorectal tumors in the chemically induced intestinal cancer model (n = 100). For the genetic intestinal cancer model, Apc^1638N/+ mice were used (n = 37). In both experiments, the number of mice bearing microscopic proliferative lesions, the number and type of lesions per mouse and the histopathological features of the adenocarcinomas were compared between Gsdme KO and wild type (WT) mice. Unfortunately, we found no major differences between Gsdme KO and WT mice, neither for the number of affected mice nor for the multiplicity of proliferative lesions in the mice. However, recent breakthroughs on gasdermin function indicate that GSDME is an executioner of necrotic cell death. Therefore, it is possible that GSDME may be important for creating an inflammatory microenvironment around the tumor. This is in line with the trend towards more severe inflammation in WT compared to Gsdme KO mice, that we observed in our study. We conclude that the effect of GSDME in tumor biology is probably more subtle than previously thought.

Role of DFNA5 in hearing loss and cancer – a comment on Rakusic et al Lieselot Croes,1,2 Ken Op de Beeck,1,2 Guy Van Camp1 1Center of Medical Genetics (CMG), Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; 2Center for Oncological Research (CORE), Department of Medicine, University of Antwerp, Antwerp, BelgiumWe would like to comment on the paper published by Rakusic et al about sudden bilateral hearing loss in gastric cancer as the only symptom of disease.1 The authors state that “Inactivated DFNA5, otherwise described in hereditary bilateral deafness, perhaps favors the development of deafness in patients with gastric cancer”.1 We believe this conclusion is erroneous. Although DFNA5 has been implicated in both hearing loss and cancer, the underlying molecular mechanisms are different and completely opposite (Figure 1). View original paper by Rakusic et al