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CCR1-mediated accumulation of myeloid cells in the liver microenvironment promoting mouse colon cancer metastasis.

Hirai H, Fujishita T, Kurimoto K, Miyachi H, Kitano S, Inamoto S, Itatani Y, Saitou M, Maekawa T, Taketo MM - Clin. Exp. Metastasis (2014)

Bottom Line: We have found four distinct types of myeloid cells recruited to the metastatic foci; neutrophils, eosinophils, monocytes and fibrocytes.Either genetic inactivation of Ccr1 or antibody-mediated neutrophil depletion reduced subsequent recruitment of fibrocytes.The results also suggest relevant mechanisms in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Transfusion Medicine and Cell Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

ABSTRACT
To understand colon cancer metastasis, we earlier analyzed a mouse model that developed liver metastasis of cancer cells disseminated from the spleen. We suggested that CCR1(+) bone marrow (BM)-derived cells are recruited to the microenvironment of disseminated colon cancer cells, and produce metalloproteinases MMP9 and MMP2, helping metastatic colonization. In the present study, we have examined these myeloid cells expressing CCR1 and/or MMPs in detail. To this end, we have established bacterial artificial chromosome (BAC)-based transgenic mouse lines in which membrane-targeted Venus fluorescent protein (mVenus) was expressed under the control of Ccr1 gene promoter. Then, myeloid cells obtained from the BM and liver metastatic foci were analyzed by the combination of flow cytometry and cytology/immunohistochemistry, in situ RNA hybridization, or quantitative RT-PCR. We have found four distinct types of myeloid cells recruited to the metastatic foci; neutrophils, eosinophils, monocytes and fibrocytes. These cell types exhibited distinct expression patterns for CCR1, MMP2 and MMP9. Namely, neutrophils found in the early phase of cancer cell dissemination expressed CCR1 exclusively and MMP9 preferentially, whereas fibrocytes accumulated in later phase expressed MMP2 exclusively. Either genetic inactivation of Ccr1 or antibody-mediated neutrophil depletion reduced subsequent recruitment of fibrocytes. The recruitment of CCR1(+) neutrophils in early phase of colon cancer dissemination appears to cause that of fibrocytes in late phase. These results implicate the key role of CCR1 in colon cancer metastasis in this mouse model, and explain why both MMP9 and MMP2 are essential as genetically demonstrated previously. The results also suggest relevant mechanisms in humans.

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A schematic representation on the roles of myeloid cells in promoting colon cancer liver metastasis. After CCL9-expressing mouse colon cancer cells (CMT93) are allowed to disseminate to the liver, CCR1+ host myeloid cells (mostly neutrophils) are recruited to the cancer cell foci in the early phase (~1 day). Neutrophils produce MMP9 and help cancer foci to expand, and at the same time recruit fibrocytes in the late phase (1–2 weeks). Fibrocytes express MMP2 and help further expansion (colonization) of the cancer foci
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Fig8: A schematic representation on the roles of myeloid cells in promoting colon cancer liver metastasis. After CCL9-expressing mouse colon cancer cells (CMT93) are allowed to disseminate to the liver, CCR1+ host myeloid cells (mostly neutrophils) are recruited to the cancer cell foci in the early phase (~1 day). Neutrophils produce MMP9 and help cancer foci to expand, and at the same time recruit fibrocytes in the late phase (1–2 weeks). Fibrocytes express MMP2 and help further expansion (colonization) of the cancer foci

Mentions: In the present study, we have demonstrated that nearly all CCR1 expressing cells accumulating at the metastatic foci are neutrophils (Figs. 1, 2). CCR1 was indeed critical for the recruitment of neutrophils, because early (day 1) accumulation of Ccr1-mVenus+ Gr-1+ neutrophils was significantly compromised in Ccr1−/− mutant mice (Fig. 6a). In addition, recruitment of monocyte/fibrocytes to the metastatic foci on day 7 was also reduced in Ccr1−/− mice. Chronologically, accumulation of neutrophils took place earlier than that of fibrocytes (Fig. 5). Moreover, antibody-mediated depletion of neutrophils caused a significant reduction in the fibrocyte number at the foci on day 7 (Supplementary Fig. 5a, b). Collectively, these results suggest that CCR1-mediated early accumulation of neutrophils triggers the fibrocyte recruitment at later stages. It is conceivable that neutrophils either recruited fibrocytes directly or stimulated monocytes to be converted to fibrocytes, or both (Fig. 8).Fig. 8


CCR1-mediated accumulation of myeloid cells in the liver microenvironment promoting mouse colon cancer metastasis.

Hirai H, Fujishita T, Kurimoto K, Miyachi H, Kitano S, Inamoto S, Itatani Y, Saitou M, Maekawa T, Taketo MM - Clin. Exp. Metastasis (2014)

A schematic representation on the roles of myeloid cells in promoting colon cancer liver metastasis. After CCL9-expressing mouse colon cancer cells (CMT93) are allowed to disseminate to the liver, CCR1+ host myeloid cells (mostly neutrophils) are recruited to the cancer cell foci in the early phase (~1 day). Neutrophils produce MMP9 and help cancer foci to expand, and at the same time recruit fibrocytes in the late phase (1–2 weeks). Fibrocytes express MMP2 and help further expansion (colonization) of the cancer foci
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4256518&req=5

Fig8: A schematic representation on the roles of myeloid cells in promoting colon cancer liver metastasis. After CCL9-expressing mouse colon cancer cells (CMT93) are allowed to disseminate to the liver, CCR1+ host myeloid cells (mostly neutrophils) are recruited to the cancer cell foci in the early phase (~1 day). Neutrophils produce MMP9 and help cancer foci to expand, and at the same time recruit fibrocytes in the late phase (1–2 weeks). Fibrocytes express MMP2 and help further expansion (colonization) of the cancer foci
Mentions: In the present study, we have demonstrated that nearly all CCR1 expressing cells accumulating at the metastatic foci are neutrophils (Figs. 1, 2). CCR1 was indeed critical for the recruitment of neutrophils, because early (day 1) accumulation of Ccr1-mVenus+ Gr-1+ neutrophils was significantly compromised in Ccr1−/− mutant mice (Fig. 6a). In addition, recruitment of monocyte/fibrocytes to the metastatic foci on day 7 was also reduced in Ccr1−/− mice. Chronologically, accumulation of neutrophils took place earlier than that of fibrocytes (Fig. 5). Moreover, antibody-mediated depletion of neutrophils caused a significant reduction in the fibrocyte number at the foci on day 7 (Supplementary Fig. 5a, b). Collectively, these results suggest that CCR1-mediated early accumulation of neutrophils triggers the fibrocyte recruitment at later stages. It is conceivable that neutrophils either recruited fibrocytes directly or stimulated monocytes to be converted to fibrocytes, or both (Fig. 8).Fig. 8

Bottom Line: We have found four distinct types of myeloid cells recruited to the metastatic foci; neutrophils, eosinophils, monocytes and fibrocytes.Either genetic inactivation of Ccr1 or antibody-mediated neutrophil depletion reduced subsequent recruitment of fibrocytes.The results also suggest relevant mechanisms in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Transfusion Medicine and Cell Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

ABSTRACT
To understand colon cancer metastasis, we earlier analyzed a mouse model that developed liver metastasis of cancer cells disseminated from the spleen. We suggested that CCR1(+) bone marrow (BM)-derived cells are recruited to the microenvironment of disseminated colon cancer cells, and produce metalloproteinases MMP9 and MMP2, helping metastatic colonization. In the present study, we have examined these myeloid cells expressing CCR1 and/or MMPs in detail. To this end, we have established bacterial artificial chromosome (BAC)-based transgenic mouse lines in which membrane-targeted Venus fluorescent protein (mVenus) was expressed under the control of Ccr1 gene promoter. Then, myeloid cells obtained from the BM and liver metastatic foci were analyzed by the combination of flow cytometry and cytology/immunohistochemistry, in situ RNA hybridization, or quantitative RT-PCR. We have found four distinct types of myeloid cells recruited to the metastatic foci; neutrophils, eosinophils, monocytes and fibrocytes. These cell types exhibited distinct expression patterns for CCR1, MMP2 and MMP9. Namely, neutrophils found in the early phase of cancer cell dissemination expressed CCR1 exclusively and MMP9 preferentially, whereas fibrocytes accumulated in later phase expressed MMP2 exclusively. Either genetic inactivation of Ccr1 or antibody-mediated neutrophil depletion reduced subsequent recruitment of fibrocytes. The recruitment of CCR1(+) neutrophils in early phase of colon cancer dissemination appears to cause that of fibrocytes in late phase. These results implicate the key role of CCR1 in colon cancer metastasis in this mouse model, and explain why both MMP9 and MMP2 are essential as genetically demonstrated previously. The results also suggest relevant mechanisms in humans.

Show MeSH
Related in: MedlinePlus