Qi Zhang1, Lu Qian Wang2, Kwan Yeung Wong2, Zhen Yu Li1, Chor Sang Chim2. 1. Department of Haematology, Affiliated Hospital of Xuzhou Medical College, Xuzhou Medical College, Xuzhou, Jiangsu Province, China. 2. Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong, Hong Kong.
Abstract
AIMS: The miR-9 family microRNAs (miRNAs) are tumour suppressor miRNAs implicated in carcinogenesis. We postulated that miR-9-1, miR-9-2 and miR-9-3 may be inactivated by aberrant promoter methylation in multiple myeloma (MM). METHODS: Methylation of miR-9-1, miR-9-2 and miR-9-3 was studied by methylation-specific PCR (MSP) in six normal controls, including three each of healthy peripheral blood (PB) or bone marrow buffy coat, 10 MM cell lines, 62 primary MM marrow samples at diagnosis and 22 at relapse/progression. RESULTS: MSP, verified by quantitative pyrosequencing, showed that the promoters of miR-9-3 and miR-9-1 were unmethylated in normal controls but methylated in 4 (40%) and 5 (50%) of 10 MM cell lines, respectively. However, the promoter of miR-9-2 was methylated in three normal PB buffy coat controls and in CD138-sorted healthy marrow plasma cells, indicating possibly tissue specific rather than tumour-specific methylation of miR-9-2, which was thus not studied further. In WL-2 cells, which were completely methylated for miR-9-3, 5-aza-2'-deoxycytidine treatment caused miR-9-3 promoter demethylation and pri-miR-9-3 re-expression. In primary samples, methylation of miR-9-3 was detected in 1 of 62 patients at diagnosis and 1 of 22 patients at relapse/progression. However, miR-9-1 methylation was absent in both primary samples at diagnosis and at relapse/progression. CONCLUSIONS: Hypermethylation of miR-9-3 and miR-9-1 is tumour-specific in MM, leading to reversible miRNA silencing. Frequent methylation of miR-9-3 and miR-9-1 in cell lines, but not in primary samples, may be acquired during in vitro culture, and indicates an unimportant role of miR-9 methylation in myelomagenesis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
AIMS: The miR-9 family microRNAs (miRNAs) are tumour suppressor miRNAs implicated in carcinogenesis. We postulated that miR-9-1, miR-9-2 and miR-9-3 may be inactivated by aberrant promoter methylation in multiple myeloma (MM). METHODS: Methylation of miR-9-1, miR-9-2 and miR-9-3 was studied by methylation-specific PCR (MSP) in six normal controls, including three each of healthy peripheral blood (PB) or bone marrow buffy coat, 10 MM cell lines, 62 primary MM marrow samples at diagnosis and 22 at relapse/progression. RESULTS: MSP, verified by quantitative pyrosequencing, showed that the promoters of miR-9-3 and miR-9-1 were unmethylated in normal controls but methylated in 4 (40%) and 5 (50%) of 10 MM cell lines, respectively. However, the promoter of miR-9-2 was methylated in three normal PB buffy coat controls and in CD138-sorted healthy marrow plasma cells, indicating possibly tissue specific rather than tumour-specific methylation of miR-9-2, which was thus not studied further. In WL-2 cells, which were completely methylated for miR-9-3, 5-aza-2'-deoxycytidine treatment caused miR-9-3 promoter demethylation and pri-miR-9-3 re-expression. In primary samples, methylation of miR-9-3 was detected in 1 of 62 patients at diagnosis and 1 of 22 patients at relapse/progression. However, miR-9-1 methylation was absent in both primary samples at diagnosis and at relapse/progression. CONCLUSIONS: Hypermethylation of miR-9-3 and miR-9-1 is tumour-specific in MM, leading to reversible miRNA silencing. Frequent methylation of miR-9-3 and miR-9-1 in cell lines, but not in primary samples, may be acquired during in vitro culture, and indicates an unimportant role of miR-9 methylation in myelomagenesis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Authors: Marina Castro Coêlho; Ingrid Costa Queiroz; José Maria Chagas Viana Filho; Sabrina Garcia de Aquino; Darlene Camati Persuhn; Naila Francis Paulo de Oliveira Journal: J Appl Oral Sci Date: 2020-04-03 Impact factor: 2.698