Use of genome-wide DNA methylation analysis to identify prognostic CpG site markers associated with longer survival time in dogs with multicentric high-grade B-cell lymphoma.
Yong Bin Teoh, Teita Ishizaki, Yumiko Kagawa, Shoko Yokoyama, Jaroslav Jelinek, Yuki Matsumoto, Hirotaka Tomiyasu, Hajime Tsujimoto, Mitsuyoshi Takiguchi, Jumpei Yamazaki
Journal of veterinary internal medicine, 38, 1, 316, 325, 2024年, ［国際誌］
英語, 研究論文（学術雑誌）, BACKGROUND: DNA methylation analysis might identify prognostic CpG sites in CHOP-treated dogs with multicentric high-grade B-cell lymphoma (MHGL) with heterogenous prognosis. OBJECTIVE: To identify prognostic CpG sites of MHGL through genome-wide DNA methylation analysis with pyrosequencing validation. ANIMALS: Test group: 24 dogs. Validation group: 100 dogs. All client-owned dogs were diagnosed with MHGL and treated with CHOP chemotherapy. METHODS: Cohort study. DNA was extracted from lymph node samples obtained via FNA. Genome-wide DNA methylation analysis using Digital Restriction Enzyme Analysis of Methylation (DREAM) was performed on the test group to identify differentially methylated CpG sites (DMCs). Bisulfite pyrosequencing was used to measure methylation status of candidate DMCs in the validation group. Median survival times (MST) were analyzed using Kaplan-Meier (log-rank) product limit method. RESULTS: DREAM analyzed 101 576 CpG sites. Hierarchical clustering of 16 262 CpG sites in test group identified group with better prognosis (MST = 55-477 days vs 10-301 days, P = .007). Volcano plot identified 1371 differentially methylated CpG sites (DMCs). DMC near the genes of FAM213A (DMC-F) and PHLPP1 (DMC-P) were selected as candidates. Bisulfite-pyrosequencing performed on validation group showed group with methylation level of DMC-F < 40% had favorable prognosis (MST = 11-1072 days vs 8-1792 days, P = .01), whereas group with the methylation level combination of DMC-F < 40% plus DMC-P < 10% had excellent prognosis (MST = 18-1072 days vs 8-1792 days, P = .009). CONCLUSION AND CLINICAL IMPORTANCE: Methylation status of prognostic CpG sites delineate canine MGHL cases with longer MST, providing owners with information on expectations of potential improved treatment outcomes.

Anaplastic oligodendroglioma with nasal invasion and systemic metastasis in a dog.
Tomoko Takahashi, Hitoshi Shiozawa, Teita Ishizaki, Kazuki Okada, Hirotaka Kondo
The Journal of veterinary medical science, 85, 10, 1052, 1056, 2023年10月17日, ［国内誌］
英語, 研究論文（学術雑誌）, An 11-year-old spayed female French bulldog was referred on suspicion of nasal tumor. Anaplastic oligodendroglioma in the olfactory bulb that was suspected to have invaded the nasal cavity was diagnosed from imaging and histopathology. Metastasis to cervical lymph nodes was suspected, with no other metastases identified. The brain-to-nasal lesion and lymph nodes were treated with hypo-fractionated radiation therapy. Nasal congestion soon resolved. About 3 months later, follow-up computed tomography revealed multiple hepatic and splenic masses, which were cytologically suspected as metastatic oligodendroglioma. Nimustine, followed by toceranib phosphate, seemed to have no effect, and the dog died on day 167. Postmortem examination revealed the primary tumor disappearance and systemic metastases. Canine oligodendroglioma can grow outside the cranial vault, and systemically metastasize.

Diverse genome-wide DNA methylation alterations in canine hepatocellular tumours.
Yu Asari, Jumpei Yamazaki, Oo Thandar, Tamami Suzuki, Keisuke Aoshima, Kyosuke Takeuchi, Ryohei Kinoshita, Sangho Kim, Kenji Hosoya, Teita Ishizaki, Yumiko Kagawa, Jaroslav Jelinek, Shoko Yokoyama, Noboru Sasaki, Hiroshi Ohta, Kensuke Nakamura, Mitsuyoshi Takiguchi
Veterinary medicine and science, 2023年07月22日, ［国際誌］
英語, 研究論文（学術雑誌）, BACKGROUND: Canine hepatocellular tumours (HCTs) are common primary liver tumours. However, the exact mechanisms of tumourigenesis remain unclear. Although some genetic mutations have been reported, DNA methylation alterations in canine HCT have not been well studied. OBJECTIVES: In this study, we aimed to analyse the DNA methylation status of canine HCT. METHODS: Tissues from 33 hepatocellular carcinomas, 3 hepatocellular adenomas, 1 nodular hyperplasia, 21 non-tumour livers from the patients and normal livers from 5 healthy dogs were used. We analysed the DNA methylation levels of 72,367 cytosine-guanine dinucleotides (CpG sites) in all 63 samples. RESULTS AND CONCLUSIONS: Although a large fraction of CpG sites that were highly methylated in the normal liver became hypomethylated in tumours from most patients, we also found some patients with less remarkable change or no change in DNA methylation. Hierarchical clustering analysis revealed that 32 of 37 tumour samples differed from normal livers, although the remaining 5 tumour livers fell into the same cluster as normal livers. In addition, the number of hypermethylated genes in tumour livers varied among tumour cases, suggesting various DNA methylation patterns in different tumour groups. However, patient and clinical parameters, such as age, were not associated with DNA methylation status. In conclusion, we found that HCTs undergo aberrant and diverse patterns of genome-wide DNA methylation compared with normal liver tissue, suggesting a complex epigenetic mechanism in canine HCT.

DNA methylation landscape of 16 canine somatic tissues by methylation-sensitive restriction enzyme-based next generation sequencing.
Jumpei Yamazaki, Yuki Matsumoto, Jaroslav Jelinek, Teita Ishizaki, Shingo Maeda, Kei Watanabe, Genki Ishihara, Junya Yamagishi, Mitsuyoshi Takiguchi
Scientific reports, 11, 1, 10005, 10005, 2021年05月11日, ［国際誌］
英語, 研究論文（学術雑誌）, DNA methylation plays important functions in gene expression regulation that is involved in individual development and various diseases. DNA methylation has been well studied in human and model organisms, but only limited data exist in companion animals like dog. Using methylation-sensitive restriction enzyme-based next generation sequencing (Canine DREAM), we obtained canine DNA methylation maps of 16 somatic tissues from two dogs. In total, we evaluated 130,861 CpG sites. The majority of CpG sites were either highly methylated (> 70%, 52.5-64.6% of all CpG sites analyzed) or unmethylated (< 30%, 22.5-28.0% of all CpG sites analyzed) which are methylation patterns similar to other species. The overall methylation status of CpG sites across the 32 methylomes were remarkably similar. However, the tissue types were clearly defined by principle component analysis and hierarchical clustering analysis with DNA methylome. We found 6416 CpG sites located closely at promoter region of genes and inverse correlation between DNA methylation and gene expression of these genes. Our study provides basic dataset for DNA methylation profiles in dogs.

Genome-wide DNA methylation analysis identifies promoter hypermethylation in canine malignant melanoma.
T Ishizaki, J Yamazaki, J Jelinek, K Aoshima, T Kimura
Research in veterinary science, 132, 521, 526, 2020年10月, ［国際誌］
英語, 研究論文（学術雑誌）, Canine malignant melanoma is a common cancer with a high mortality rate. Although previous studies have evaluated various aspects of this tumour, the exact mechanism of tumourigenesis remains unknown. Epigenetic mechanisms, such as DNA methylation, have recently gained attention as aetiological factors for neoplasia in humans. This study aimed to analyse genome-wide DNA methylation patterns in canine malignant melanoma based on next-generation sequencing data. A total of 76,213 CpG sites, including 29,482 sites in CpG islands (CGIs), were analysed using next-generation sequencing of methylation-specific signatures, obtained by sequential digestion with enzymes, to compare normal oral mucosal samples from four healthy dogs, four canine melanoma cell lines (3 oral cavity and 1 skin), and five clinical samples of oral canine melanoma. Malignant melanoma showed increased methylation at thousands of normally unmethylated CpG sites in CGIs and decreased methylation at normally methylated CpG sites in non-CGIs. Interestingly, the promoter regions of 81-393 genes were hypermethylated; 23 of these genes were present in all melanoma cell lines and melanoma clinical samples. Among these 23 genes, six genes with "sequence-specific DNA binding" annotation were significantly enriched, including three Homeobox genes-HMX2, TLX2, and HOXA9-that may be involved in the tumourigenesis of canine malignant melanoma. This study revealed widespread alterations in DNA methylation and a large number of hypermethylated genes in canine malignant melanoma.

Genome-wide DNA methylation analysis in canine gastrointestinal lymphoma.
Hiroshi Ohta, Jumpei Yamazaki, Jaroslav Jelinek, Teita Ishizaki, Yumiko Kagawa, Nozomu Yokoyama, Noriyuki Nagata, Noboru Sasaki, Mitsuyoshi Takiguchi
The Journal of veterinary medical science, 82, 5, 632, 638, 2020年03月25日, ［査読有り］, ［国内誌］
英語, 研究論文（学術雑誌）, DNA methylation is the covalent modification of methyl groups to DNA mostly at CpG dinucleotides and one of the most studied epigenetic mechanisms that leads to gene expression variability without affecting the DNA sequence. Genome-wide analysis of DNA methylation identified the signatures that could define subtypes of human lymphoma patients. The objective of this study was to conduct the genome-wide analysis of DNA methylation in dogs with gastrointestinal lymphoma (GIL). Genomic DNA was extracted from endoscopic biopsies from 10 dogs with GIL. We performed Digital Restriction Enzyme Assay of DNA Methylation (DREAM) for genome-wide DNA methylation analysis that could provide highly quantitative information on DNA methylation levels of CpG sites across the dog genome. We successfully obtained data of quantitative DNA methylation level for 148,601-162,364 CpG sites per GIL sample. Next, we analyzed 83,132 CpG sites to dissect the differences in DNA methylation between GIL and normal peripheral blood mononuclear cells (PBMCs). We found 383-3,054 CpG sites that were hypermethylated in GIL cases compared to PBMCs. Interestingly, 773 CpG sites including promoter regions of 61 genes were identified to be commonly hypermethylated in more than half of the cases, suggesting conserved DNA methylation patterns that are abnormal in GIL. This study revealed that there was a large number of hypermethylated sites that are common in most of canine GIL. These abnormal DNA methylation could be involved in tumorigenesis of the canine GIL.

Long interspersed nucleotide element-1 hypomethylation in canine malignant mucosal melanoma.
Teita Ishizaki, Jumpei Yamazaki, Shinji Meagawa, Nozomu Yokoyama, Keisuke Aoshima, Mitsuyoshi Takiguchi, Takashi Kimura
Veterinary and comparative oncology, 2020年03月18日, ［査読有り］, ［国際誌］
英語, Canine malignant melanoma is a common cancer with a high mortality rate and is a clinically important disease. DNA methylation has been considered to be a potential tumorigenic mechanism through aberrant DNA methylation at promoter region which represses gene transcription. Global hypomethylation could also facilitate chromosome instability. There are few reports regarding DNA methylation in canine malignant melanoma; therefore, the purpose of this study was to examine DNA methylation status of long interspersed nucleotide element-1 (LINE-1) to be a surrogate marker of genome-wide methylation changes in this disease. We measured levels of DNA methylation of two adjacent cytosine-guanine sites on CpG island (CGI) at the putative promoter of canine LINE-1 sequence by bisulphite-pyrosequencing in 41 canine melanoma patient samples as well as six cell lines compared with normal mucosae. The survival rates were obtained from owners or medical records. We found DNA methylation levels of LINE-1 in normal mucosae were methylated. Interestingly, both melanoma cell lines and clinical melanoma samples showed remarkable hypomethylation. In addition, patients with lower LINE-1 methylation showed worse prognosis than those with higher LINE-1 methylation, though the difference did not reach statistical significance (P = .09). Here, we demonstrate that hypomethylation of LINE-1 is an epigenetically aberrant feature in canine melanoma with possible prognostic value.

Veterinary Oncology　　　　　　　　　　　　　　　
石崎 禎太, 脾臓の細胞診
インターズー, 2015年04月

CAP (Companion Animal Practice)　　　　　　　　　　　　　　　
石崎 禎太, 病理学的にみた鼻腔内腫瘍
緑書房, 2013年09月

教育講演 細胞診断学　　　　　　　　　　　　　　　
第15回 日本獣医がん学会, 2016年06月
［招待講演］

Diagnostic cytology for neoplastic diseases　　　　　　　　　　　　　　　
Teita Ishizaki
AMAMS, 2015年10月
［招待講演］

米国獣医臨床病理学専門医への道　　　　　　　　　　　　　　　
石崎 禎太
日本獣医臨床病理学会 2015年学術大会, 2015年05月30日
［招待講演］

これくらいは知っておきたい腎泌尿器検査の解釈　　　　　　　　　　　　　　　
石崎 禎太
第11回 鹿児島大学小動物臨床フォーラム, 2015年03月01日
［招待講演］

胸腹水のケミストリーと細胞診　　　　　　　　　　　　　　　
石崎 禎太
日本獣医臨床病理学会 2014年学術大会, 2014年05月31日