title: Frequent epigenetic inactivation of cystatin M in breast carcinoma.
abstract: Cystatin M is a potent endogenous inhibitor of lysosomal cysteine proteases. In breast carcinoma, cystatin M expression is frequently downregulated. It has been shown that cystatin M expression suppressed growth and migration of breast cancer cells. We examined the methylation status of the CpG island promoter of cystatin M in four breast cancer cell lines (MDAMB231, ZR75-1, MCF7 and T47D), in 40 primary breast carcinoma and in corresponding normal tissue probes by combined bisulphite restriction analysis. To investigate the effects of cystatin M expression on the growth of breast carcinoma, cystatin M was transfected in T47D. The cystatin M promoter was highly methylated in all four-breast cancer cell lines. Primary breast tumours were significantly more frequently methylated compared to normal tissue samples (60 vs 25%; P=0.006 Fisher's exact test). Treatment of breast cancer cells with 5-aza-2'-deoxycytidine (5-Aza-CdR), reactivated the transcription of cystatin M. Transfection of breast carcinoma cells with cystatin M caused a 30% decrease in colony formation compared to control transfection (P=0.002). Our results show that cystatin M is frequently epigenetically inactivated during breast carcinogenesis and cystatin M expression suppresses the growth of breast carcinoma. These data suggest that cystatin M may encode a novel epigenetically inactivated candidate tumour suppressor gene.
authors.affiliation: AWG Tumour Genetics of the Medical Faculty, Institute for Human Genetics, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Schagdarsurengin
authors.forename: G P
authors.initials: GP
authors.lastname: Pfeifer
authors.forename: R
authors.initials: R
authors.lastname: Dammann
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics; D055332:Cystatin M; D015891:Cystatins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D020868:Gene Silencing; D006801:Humans; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism
chemical_list: C525104:CST6 protein, human; D055332:Cystatin M; D015891:Cystatins; D025521:Tumor Suppressor Proteins