Comprehensive analysis of mutant ERa found in cancers to reveal their aberrant functions

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K07651
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 50010:Tumor biology-related
• Research Institution: Japanese Foundation for Cancer Research
• Principal Investigator: NAKADAI Tomoyoshi 公益財団法人がん研究会, がん研究所 がんエピゲノムプロジェクト, 研究員 (10364770)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: ERa / Breast cancer / Mutation / FoxA1 / NcoA2 / ATAC-seq / ChIP-seq / K303R

Outline of Final Research Achievements

MB453 inducibly expressing mutant K303R was established and ATAC/ChIP-seq analyses were performed. The results showed that both of wild type and the mutant K303R associated with DNA-bound FoxA1 indirectly, but only the mutant K303R opened those regions. Moreover, biochemical analyses showed that the mutant K303R induced the association of NcoA2 to FoxA1/DNA complex. These results proposed the novel mechanism of breast cancer development by the mutant K303R.
Nine ERa mutants, which were shown to exhibit functional abnormalities in the luciferase assay, were also introduced into MB453. ATAC/ChIP-seq analyses revealed that mutant A86V/S463P showed the constitutive active phenotype as Y537S, and also mutants E247K/E380Q showed the novel abnormality (induced association to AP-1 binding region).

Free Research Field

遺伝子発現制御

Academic Significance and Societal Importance of the Research Achievements

これまで高頻度変異体ERαの解析によるがんの治療や診断への応用がすすんでいる。一方中程度以下の変異については、未解析かつがん化との関連性を統計学的に見出すことも難しい。本研究はこれらの問題点へ切り込むことを目的とし、ルシフェラーゼアッセイやNGS等の網羅的解析を行い、複数の変異体の異常性の有無と新規異常性について明らかにした。特に変異体K303Rの異常性の分子機構（NcoA2のFoxA1会合の促進）を解明、新規がん化機構の提唱を行った。同時に野生型ERαの間接的FoxA1への会合を発見、野生型ERaの新機能を発見した。以上、本研究はERaの新規機能とERα変異を有するがんの理解へつながった。