LINE-1が癌に飛び込む実頻度が初めて（？）報告されたよ。サイエンス

ヒト疾病におけるトランスポゾンの挿入イベントは、これまで散発的に報告されてきた。古くは1988年のKazazianによる血友病遺伝子へのLINE-1飛び込みと破壊と血友病のde-novo発症。もうひとつ1992年の中村研時代の三木さんによる乳癌（APC遺伝子に飛び込んだLINE-1による発症）が小生には印象的。今回、このレトロトランスポジションが比較的頻度高くヒト癌で生じているという論文がScienceに掲載された。

このデータは小生がこの２０年で待ち望んでいたLandscapeの一つだ。こんな頻度なのかというのが感想である。症例報告的に少ない訳でもないのね、というのがもう一つの感想である。あるんだね、実際のところ、レトロトランスポジション

1. Y. Mik　et al　 Disruption of the APC gene by a retrotransposal insertion of L1 sequence in a colon cancer. Cancer Res. 52, 643 (1992).　　Abstract/FREE Full Text
   
   
2. Nature 332, 164 - 166 (10 March 1988); doi:10.1038/332164a0 Haemophilia A resulting from de novo insertion of L1 sequences represents a novel mechanism for mutation in man H. Kazazian et al
   

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Science 24 August 2012: 967-971.
Published online 28 June 2012

• Received for publication 19 March 2012.
• Accepted for publication 15 June 2012.

Landscape of Somatic Retrotransposition in Human Cancers

• Eunjung Lee,　Rebecca Iskow,　Lixing Yang,他多数　and The Cancer Genome Atlas Research Network

Abstract

Transposable elements (TEs) are abundant in the human genome, and some are capable of generating new insertions through RNA intermediates. In cancer, the disruption of cellular mechanisms that normally suppress TE activity may facilitate mutagenic retrotranspositions. We performed single-nucleotide resolution analysis of TE insertions in 43 high-coverage whole-genome sequencing data sets from five cancer types. We identified 194 high-confidence somatic TE insertions, as well as thousands of polymorphic TE insertions in matched normal genomes. Somatic insertions were present in epithelial tumors but not in blood or brain cancers. Somatic L1 insertions tend to occur in genes that are commonly mutated in cancer, disrupt the expression of the target genes, and are biased toward regions of cancer-specific DNA hypomethylation, highlighting their potential impact in tumorigenesis.

somaticな挿入はほとんどがLINE-1でありAluは少ないようだ。

Fig 2のレジェンドから引用すると・・・・

• Frequency of high-confidence somatic L1 insertions varies across 5 colorectal, 7 prostate, 8 ovarian, 7 multiple myeloma, and 16 glioblastoma tumors. Three epithelial cancers (colorectal, prostate, and ovarian) show frequent somatic L1 insertions, whereas no insertions are observed in the blood and brain cancers. One colorectal tumor (CR3518) contains 102 L1 insertions, increasing the average somatic event frequency for colorectal tumors from 9 to 28 when this sample is included.

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