The 3p14.2 tumour suppressor ADAMTS9 is inactivated by promoter CpG methylation and inhibits tumour cell growth in breast cancer |
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Authors: | Hongbin Zhang Fang Yu Qianqian Li Cui Tan Hongying Xu Jianming Ying Lili Li Dejuan Yang Weiyan Peng Jun Tang Shuman Li Guosheng Ren Qian Tao Tingxiu Xiang |
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Institution: | 1. Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China;2. The Second people's hospital of JingDe Zhen, Jiangxi, China;3. The Sixth people's hospital of Chongqing, Chongqing, China;4. Cancer Epigenetics Laboratory, State Key Laboratory of Oncology in South China, Department of Clinical Oncology, Sir YK Pao Center for Cancer and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong and CUHK Shenzhen Research Institute, Hong Kong, China;5. Department of Pathology, Cancer Hospital, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing, China |
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Abstract: | Chromosome region 3p12‐14 is an important tumour suppressor gene (TSG) locus for multiple cancers. ADAMTS9, a member of the metalloprotease large family, has been identified as a candidate 3p14.2 TSG inactivated by aberrant promoter CpG methylation in several carcinomas, but little known about its expression and function in breast cancer. In this report, ADAMTS9 expression and methylation was analysed in breast cancer cell lines and tissue samples. ADAMTS9 RNA was significantly down‐regulated in breast cancer cell lines (6/8). After treating the cells with demethylation agent Aza and TSA, ADAMTS9 expression was dramatically increased. Bisulphite genomic sequencing and methylation‐specific PCR detected promoter methylation, which was associated with decreased ADAMTS9 expression. Hypermethylation was also detected in 130/219 (59.4%) of primary tumours but only in 4.5% (2/44) of paired surgical margin tissues. Ectopic expression of ADAMTS9 in tumor cells induced significant growth suppression, cell cycle arrest at the G0/G1 phase, enhanced apoptosis and reduced cell migration and invasion. Conditioned culture medium from ADAMTS9‐transfected BT549 cells markedly disrupted tube formation ability of human umbilical vein endothelial cell (HUVEC) in Matrigel. Furthermore, ADAMTS9 inhibited AKT signaling and its downstream targets (MDM2, p53, p21, p27, E‐cadherin, VIM, SNAIL, VEGFA, NFκB‐p65 and MMP2). In addition, we demonstrated, for the first time, that ADAMTS9 inhibits AKT signaling, through suppressing its upstream activators EGFR and TGFβ1/TβR(I/II) in breast cancer cells. Our results suggest that ADAMTS9 is a TSG epigenetically inactivated in breast cancer, which functions through blocking EGFR‐ and TGFβ1/TβR(I/II)‐activated AKT signaling. |
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Keywords: | ADAMTS9 tumour suppressor methylation
EGFR
TGFβ |
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