Abdul K Siraj1, Poyil Pratheeshkumar1, Sandeep Kumar Parvathareddy1, Rong Bu1, Tariq Masoodi1, Kaleem Iqbal1, Maha Al-Rasheed1, Fouad Al-Dayel2, Saif S Al-Sobhi3, Ali S Alzahrani4, Mohammed Al-Dawish5, Khawla S Al-Kuraya6. 1. Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Center, Riyadh, 11211, Saudi Arabia. 2. Department of Pathology, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia. 3. Department of Surgery, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia. 4. Endocrinology, Research Centre. King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. 5. Department of Diabetes and Endocrinology, Prince Sultan Military Medical City, Riyadh 11159, Saudi Arabia. 6. Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Center, Riyadh, 11211, Saudi Arabia. Electronic address: Kkuraya@kfshrc.edu.sa.
Abstract
BACKGROUND: Thyroid cancer is the second most common cancer affecting Saudi women after breast cancer, with papillary thyroid carcinoma (PTC) accounting for 80-90% of thyroid cancers. DNA methyltransferases affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. METHODS: We sought to evaluate the frequency of DNA methyltransferase 3A (DNMT3A) alterations in a large cohort of >1000 PTC cases using exome sequencing, capture sequencing, immunohistochemistry and methylation-specific polymerase chain reaction. We also performed in vitro analysis to investigate the role of DNMT3A methylation in PTC cell lines. RESULTS: DNMT3A pathogenic mutations were noted in 1.2% (12/1013) of PTC cases. Reduced/loss of DNMT3A expression was seen in 59.8% (579/968) of PTC cases and was significantly associated with the DNMT3A mutation (p = 0.0120). DNMT3A alterations (mutation and/or loss of expression) were associated with aggressive clinical parameters and a poor outcome. The promoter region of the DNMT3A gene was methylated in 57.1% of PTC cases tested and was significantly associated with reduced DNMT3A protein expression (p = 0.0253). Treatment of the methylated PTC cell line with 5-aza-2'-deoxycytidine resulted in demethylation of the DNMT3A gene, leading to restoration of its expression. Demethylation significantly potentiated the TRAIL-mediated apoptosis in PTC cells. Interestingly, silencing of DNMT3A using siRNA suppressed TRAIL-mediated apoptosis. CONCLUSION: These findings suggest that DNMT3A alterations play an important role in PTC pathogenesis and demethylation agents can be used to restore the function of DNMT3A in a subset of patients with PTC.
BACKGROUND: Thyroid cancer is the second most common cancer affecting Saudi women after breast cancer, with papillary thyroid carcinoma (PTC) accounting for 80-90% of thyroid cancers. DNA methyltransferases affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. METHODS: We sought to evaluate the frequency of DNA methyltransferase 3A (DNMT3A) alterations in a large cohort of >1000 PTC cases using exome sequencing, capture sequencing, immunohistochemistry and methylation-specific polymerase chain reaction. We also performed in vitro analysis to investigate the role of DNMT3A methylation in PTC cell lines. RESULTS:DNMT3A pathogenic mutations were noted in 1.2% (12/1013) of PTC cases. Reduced/loss of DNMT3A expression was seen in 59.8% (579/968) of PTC cases and was significantly associated with the DNMT3A mutation (p = 0.0120). DNMT3A alterations (mutation and/or loss of expression) were associated with aggressive clinical parameters and a poor outcome. The promoter region of the DNMT3A gene was methylated in 57.1% of PTC cases tested and was significantly associated with reduced DNMT3A protein expression (p = 0.0253). Treatment of the methylated PTC cell line with 5-aza-2'-deoxycytidine resulted in demethylation of the DNMT3A gene, leading to restoration of its expression. Demethylation significantly potentiated the TRAIL-mediated apoptosis in PTC cells. Interestingly, silencing of DNMT3A using siRNA suppressed TRAIL-mediated apoptosis. CONCLUSION: These findings suggest that DNMT3A alterations play an important role in PTC pathogenesis and demethylation agents can be used to restore the function of DNMT3A in a subset of patients with PTC.
Authors: Sara Mellid; Javier Coloma; Bruna Calsina; María Monteagudo; Juan M Roldán-Romero; María Santos; Luis J Leandro-García; Javier Lanillos; Ángel M Martínez-Montes; Cristina Rodríguez-Antona; Cristina Montero-Conde; Joaquín Martínez-López; Rosa Ayala; Xavier Matias-Guiu; Mercedes Robledo; Alberto Cascón Journal: Cancers (Basel) Date: 2020-11-09 Impact factor: 6.639