Fhit イデンシ ノックアウト マウス ニ オケル シュヨウ オヨビ チョウカン イジョウ ノ ハッセイ ニ カンスル ケンキュウ

京都大学0048新制・課程博士博士(医学)甲第12907号医博第3067号新制||医||943(附属図書館)UT51-2007-H180京都大学大学院医学研究科生理系専攻(主査)教授 野田 亮, 教授 千葉 勉, 教授 鍋島 陽一学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDA

Antitumor activity of the MEK inhibitor trametinib on intestinal polyp formation in Apc[Δ716] mice involves stromal COX-2

Extracellular signal-regulated kinase is an MAPK that is most closely associated with cell proliferation, and the MEK/ERK signaling pathway is implicated in various human cancers. Although epidermal growth factor receptor, KRAS, and BRAF are considered major targets for colon cancer treatment, the precise roles of the MEK/ERK pathway, one of their major downstream effectors, during colon cancer development remain to be determined. Using Apc[Δ716] mice, a mouse model of familial adenomatous polyposis and early-stage sporadic colon cancer formation, we show that MEK/ERK signaling is activated not only in adenoma epithelial cells, but also in tumor stromal cells including fibroblasts and vascular endothelial cells. Eight-week treatment of Apc[Δ716] mice with trametinib, a small-molecule MEK inhibitor, significantly reduced the number of polyps in the large size class, accompanied by reduced angiogenesis and tumor cell proliferation. Trametinib treatment reduced the COX-2 level in Apc[Δ716] tumors in vivo and in primary culture of intestinal fibroblasts in vitro. Antibody array analysis revealed that trametinib and the COX-2 inhibitor rofecoxib both reduced the level of CCL2, a chemokine known to be essential for the growth of Apc mutant polyps, in intestinal fibroblastsin vitro. Consistently, trametinib treatment reduced the Ccl2 mRNA level in Apc[Δ716] tumors in vivo. These results suggest that MEK/ERK signaling plays key roles in intestinal adenoma formation in Apc[Δ716] mice, at least in part, through COX-2 induction in tumor stromal cells

Inactivation of chemokine (C-C motif) receptor 1 (CCR1) suppresses colon cancer liver metastasis by blocking accumulation of immature myeloid cells in a mouse model

Recent reports have suggested critical roles of myeloid cells in tumor invasion and metastasis, although these findings have not led to therapeutics. Using a mouse model for liver dissemination, we show that mouse and human colon cancer cells secrete CC-chemokine ligands CCL9 and CCL15, respectively, and recruit CD34+ Gr-1− immature myeloid cells (iMCs). They express CCL9/15 receptor CCR1 and produce matrix metalloproteinases MMP2 and MMP9. Lack of the Ccr1, Mmp2, or Mmp9 gene in the host dramatically suppresses outgrowths of disseminated tumors in the liver. Importantly, CCR1 antagonist BL5923 blocks the iMC accumulation and metastatic colonization and significantly prolongs the survival of tumor-bearing mice. These results suggest that CCR1 antagonists can provide antimetastatic therapies for patients with disseminated colon cancer in the liver

Loss of SMAD4 From Colorectal Cancer Cells Promotes CCL15 Expression to Recruit CCR1(+) Myeloid Cells and Facilitate Liver Metastasis.

[Background & Aims]Loss of the tumor suppressor SMAD4 correlates with progression of colorectal cancer (CRC). In mice, colon tumors that express CCL9 recruit CCR1+ myeloid cells, which facilitate tumor invasion and metastasis by secreting matrix metalloproteinase 9. [Methods]We used human CRC cell lines to investigate the ability of SMAD4 to regulate expression of CCL15, a human ortholog of mouse CCL9. We used immunohistochemistry to compare levels of CCL15 and other proteins in 141 samples of human liver metastases. [Results]In human CRC cell lines, knockdown of SMAD4 increased CCL15 expression, and overexpression of SMAD4 decreased it. SMAD4 bound directly to the promoter region of the CCL15 gene to negatively regulate its expression; transforming growth factor-β increased binding of SMAD4 to the CCL15 promoter and transcriptional repression. In livers of nude mice, SMAD4-deficient human CRC cells up-regulated CCL15 to recruit CCR1+ cells and promote metastasis. In human tumor samples, there was a strong inverse correlation between levels of CCL15 and SMAD4; metastases that expressed CCL15 contained 3-fold more CCR1+cells than those without CCL15. Patients with CCL15-expressing metastases had significantly shorter times of disease-free survival than those with CCL15-negative metastases. CCR1+ cells in the metastases expressed the myeloid cell markers CD11b and myeloperoxidase, and also matrix metalloproteinase 9. [Conclusions]In human CRC cells, loss of SMAD4 leads to up-regulation of CCL15 expression. Human liver metastases that express CCL15 contain higher numbers CCR1+ cells; patients with these metastases have shorter times of disease-free survival. Reagents designed to block CCL15 recruitment of CCR1+ cells could prevent metastasis of CRC to liver