英国研究人员日前报告说，人类基因组中一些“垃圾DNA”产生的物质与乳腺癌等癌症存在相关性，这项发现有助于研发新的癌症治疗方法。$ i6 l% F% Q! \% X, P- a
' P, U- M- R! ^$ J' ^$ S英国诺丁汉大学等机构研究人员在美国《基因组学》杂志上报告说，他们发现人类基因组中名为L1的DNA序列会导致生成一些反常产物，而这些产物多见于乳腺癌细胞中。 5 H9 V% M/ L/ U8 i+ K V R- ?Genomics December 2009 doi:10.1016/j.ygeno.2009.08.013 . v0 a, ~; H# J* M; b: ]
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Isolation of cancer-specific chimeric transcripts induced by hypomethylation of the LINE-1 antisense promoter3 x3 a3 Y# r+ e) C) y+ a) l, ?
* u$ a# v8 ^8 o$ C4 L# P0 L+ SHazel A. Cruickshanksa, b and Cristina Tufarelli, a, b, 2 U$ h W7 ^9 ~. i3 B& b& g6 J2 n+ b! O' |+ b# v% Y9 n2 E
aWolfson Centre for Stem Cells, Tissue Engineering and Modelling (STEM), Centre for Biomolecular Sciences, University of Nottingham, Nottingham, NG7 2RD, UK 5 h! i6 W) r8 M) _# Z1 b: d+ g6 q4 KbDepartment of Genetics, University of Leicester, Leicester, LE1 7RH, UK ; n* c$ d# W4 ^ 1 c8 N: q- f$ I' S0 f6 m4 \, o: q' dThe antisense promoter of human LINE-1 (L1) retroelements can direct transcription of adjacent unique genomic sequences generating chimeric RNAs, which can perturb transcription of neighbouring genes. As L1 elements constitute 17% of the human genome, chimeric transcription is potentially widespread, but the extent to which this occurs is largely unknown. Using a genome-wide screen we have isolated novel chimeric transcripts that are unique to breast cancer cell lines, primary tumours and colon cancer cells. Expression of the cancer-specific chimeric transcripts can be induced in non-malignant breast epithelial cells by the demethylating drug 5-azacytidine. These findings indicate that loss of L1 methylation in cancer cells is linked to the expression of L1-chimeric transcripts which may therefore constitute a useful set of markers of malignancy.