並列タイトル等T-box Transcription Factor BRACHYURY and SOX2 Increase Self-Renewal and Invasive Phenotype in Adenoid Cystic Carcinoma : Implication for a New Therapeutic Principle
学位博士(歯学)
Doctor of Philosophy in Dental Science
一般注記博士論文全文, 博士論文要旨, 最終試験結果の要旨, 論文審査の要旨
Background: The high frequencies of recurrence and distant metastasis of adenoid cystic carcinoma (ACC) emphasize the need to better understand the biological factors associated with these outcomes. Recent studies suggest that epithelial–mesenchymal transition (EMT) correlates with cancer metastasis. In addition, there is growing evidence of the association of EMT with cancer stem cells (CSCs). Recently, we showed that the T-box transcription factor BRACHYURY could be a strong regulator of EMT. Further, we previously established the metastatic ACCS-M GFP cell line and reported that SOX2 knockdown partially inhibits EMT phenotypes of ACCS-M GFP cells. Thus, in this study, we further tested whether BRACHYURY and SOX2 is a regulator of cancer stemness by means of forced expression and silencing of these genes in adenoid cystic carcinoma (ACC) cell lines.
Methods: BRACHYURY, SOX2, or both were transfected into ACC cell lines. Short hairpin RNA (shRNA) silencing of these genes was also performed. We analysed these cell lines with respect to self-renewal phenotypes using a sphere-formation assay, and we assessed the expression levels of EMT markers and stem cell markers using real-time reverse transcription-polymerase chain reaction (RT-PCR). Cell migration and invasiveness in vitro were evaluated using a wound healing assay and a tumor cell dissemination assay, respectively. Characteristics of CSCs were also analyzed by sphere-forming ability and in vivo tumorigenicity.
Results: Forced expression of BRACHYURY or SOX2 slightly increased expression of EMT and stem cell markers and the self-renewal phenotype. The expression levels, however, were much lower compared to those of cancer stem cell-like cells. Forced co-expression of BRACHYURY and SOX2 strongly upregulated EMT and stem cell markers and the self-renewal phenotype. Cell migration and invasiveness in vitro were also remarkably enhanced. These synergistic effects increased expression levels of FIBRONECTIN, SNAIL, SLUG, ZEB1, and TGF-β2. In particular, the effects on FIBRONECTIN and TGF-β2 were significant. BRACHYURY knockdown significantly inhibited cell migration and invasion, and decreased tumorigenicity in ACC cells.
Conclusions: We found that BRACHYURY and SOX2 synergistically promote cancer stemness in ACC cells. This finding points to the importance of gene or protein networks associated with BRACHYURY and SOX2 in the development and maintenance of the CSC phenotype. This study demonstrates that BRACHYURY knockdown reduces invasiveness of CSCs in vivo, suggesting that BRACHYURY silencing may be a useful therapeutic tool for salivary gland carcinoma including adenoid cystic carcinoma.
The part of this thesis is originally based on:
Naonari Akimoto, Kodai Nakamura, Hiroshi Hijioka, Kenichi Kume, Yoshiaki Matsumura and Tsuyoshi Sugiura
Transfection of T-Box Transcription Factor BRACHYURY and SOX2 Synergistically Promote Self-Renewal and Invasive Phenotype in Oral Cancer Cells
International Journal of Molecular Sciences 2018, 19(11):3620
DOI: 10.3390/ijms19113620
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）