ANK2 Hypermethylation in Canine Mammary Tumors and Human Breast Cancer.

Johannes J Schabort,Seok Won Kim,Kang-Hoon Lee,A-Reum Nam,Je-Yoel Cho,Jeong Eon Lee

doi:10.3390/ijms21228697

Abstract

Canine mammary tumors (CMT) constitute the most common tumor types found in female dogs. Understanding this cancer through extensive research is important not only for clinical veterinary applications, but also in the scope of comparative oncology. The use of DNA methylation as a biomarker has been noted for numerous cancers in the form of both tissue and liquid biopsies, yet the study of methylation in CMT has been limited. By analyzing our canine methyl-binding domain sequencing (MBD-seq) data, we identified intron regions of canine ANK2 and EPAS1 as differentially methylated regions (DMGs) in CMT. Subsequently, we established quantitative methylation specific PCR (qMSP) of ANK2 and EPAS1 to validate the target hypermethylation in CMT tissue, as well as cell free DNA (cfDNA) from CMT plasma. Both ANK2 and EPAS1 were hypermethylated in CMT and highlighted as potential tissue biomarkers in CMT. ANK2 additionally showed significant hypermethylation in the plasma cfDNA of CMT, indicating that it could be a potential liquid biopsy biomarker as well. A similar trend towards hypermethylation was indicated in HBC at a specific CpG of the ANK2 target on the orthologous human region, which validates the comparative approach using aberrant methylation in CMT.

Highlights

Canine mammary tumors (CMT) are the most common neoplasia diagnosed in female dogs and are found to be malignant in approximately 50% of cases [1,2,3,4]
These identified CMT differentially methylated regions (DMRs) were found in CpG islands in the 21st and 1st introns of ANK2 and EPAS1, respectively, and the increase in methylation in the cancer samples are shown via linear mixed model (LMM) with thresholds of both 10% and 5% (Figure 1C)
CMT is a common malignancy in female dogs and, in the scope of using dogs as animal models for human disease, its study can be translated to human breast cancer (HBC)

Summary

Introduction

Canine mammary tumors (CMT) are the most common neoplasia diagnosed in female dogs and are found to be malignant in approximately 50% of cases [1,2,3,4]. The expedited study rate due to faster disease progression and shorter lifespan, histological and mechanistic similarities [5], spontaneous disease occurrence, and exposure to similar environments as humans make dogs ideal models for comparative oncology [11,12]. In CMT, aberrant methylation has been reported for a few genes such as ERα [17], DAPK1, MGMT [18], and BRCA1 [19], yet gene-specific methylation of CMT remains largely unknown. These methylation changes are often observed early during carcinogenesis [20] making them ideal biomarkers for early detection and prognosis. Tissue biomarkers remain the standard for cancer diagnosis and prognosis, yet in recent years the interest in liquid biopsy biomarkers have risen [21]

Methods

Results

Conclusion