Loss of SMAD4 Promotes Colorectal Cancer Progression by Accumulation of Myeloid-Derived Suppressor Cells through the CCL15–CCR1 Chemokine Axis

We previously reported that loss of SMAD4 promotes chemokine CCL15 expression to recruit CCR1(+) myeloid cells via the CCL15-CCR1 axis, which facilitates metastasis of colorectal cancer to the liver. The purposes of this study were to investigate whether essentially the same mechanism works in tumor invasion of the primary colorectal cancer and to evaluate the clinical importance of CCL15 expression and CCR1(+) cell accumulation.Using human...