Differentially expressed genes of CD11b+Gr-1+ myeloid cells

Differentially expressed genes of CD11b+Gr-1+ immature myeloid cells (IMCs) in the bone marrow and colonic tumor setting of histidine decarboxylase (HDC)-KO mice were examined by microarray (Affymetrix Mouse 430.2 array). Myeloid differentiation-related candidate genes were sought to be isolated and functionally studied. Total RNA of HDC-expressing CD11b+Gr-1+ IMCs of bone marrow were extracted from HDC-EGFP and HDC-EGFP/HDC-KO mice (3 mice in each group). CD11b+Gr-1+ myeloid-derived suppressor cells (MDSCs) of colon tumor were sorted from 10-12 colon tumors of WT and HDC-KO mice (5 mice in each group), and pooled to extract total RNA for microarray studies. Two technical replicates for each of the four groups. Four sets of comparisons were performed to screen for upregulated or downregulated genes in the HDC-KO CD11b+Gr-1+ IMCs or MDSCs (experiment group) compared to the WT group: (1) HDC-expressing CD11b+Gr-1+ IMCs of bone marrow of HDC KO mice compared to bone marrow IMCs of WT mice; (2) CD11b+Gr-1+ MDSCs in tumors of HDC-KO mice compared to WT mice; (3) CD11b+Gr-1+ MDSCs of WT colon tumors compared to IMCs in the WT bone marrow; and (4) CD11b+Gr-1+ MDSCs of colon tumors of HDC-KO mice compared to IMCs in the bone marrow of HDC-KO mice.