Summary of studies, which demonstrated relationships between levels of MDSCs and tumorigenesis in CRC patients

Sample typeMDSC phenotypeNumber of samplesMain findingsReferences
Peripheral bloodLin–/lowHLA-DR CD11b+CD33+ MDSCs64 patientsIncreased percentage and the absolute number of Lin–/lowHLA-DRCD11b+CD33+ MDSCs compared with healthy controls. This increase is closely correlated with clinical cancer stage and tumor metastasis but not primary tumor size[20]
Peripheral bloodCD11b+CD33+HLA-DR MDSCs23 patients with stage IV metastatic CRCPatients with advanced CRC display enhanced MDSC levels and reduced CD247 expression[37]
Peripheral blood and tumor tissuesCD33+HLA-DR MDSC49 CRC patientsA considerable increase in the percentage of CD33+HLA-DR MDSCs was observed in the peripheral blood and tumor tissues of CRC patients as compared with healthy controls[18]
Peripheral blood and tumor tissuesCD33+CD11b+HLA-DR32 age-matched healthy donors and 42 patients with CRC at the time of first diagnosisCRC patients had elevated levels of CD33+CD11b+HLA-DR MDSCs in primary tumor tissues and in peripheral blood. These elevated circulating MDSCs were correlated with advanced TNM stages and lymph node metastases[42]
Tumor tissuesCD45+LinHLA-DR CD11b+CD33+CD66b+154 patients with colorectal adenocarcinomaActivated inflammatory-DCs induced γδT17 cells to secrete IL-8, tumor necrosis factor alpha, and GM-CSF with a concomitant accumulation of immunosuppressive PMN-MDSCs in the tumor[44]
Tumor tissuesCD33+CD11b+HLA-DR MDSCs145 newly diagnosed CRC patients who did not accept any preoperative chemoradiotherapyA significant association between CD33+ MDSC number and YAP1 and PTEN levels in CRC patients. The CD33+ MDSCs, YAP1, and PTEN were identified as predictors for the prognosis of CRC patients[46]
Peripheral blood and tumor tissuesCD33+CD11b+HLA-DR–/lowCD15+CD33+CD11b+HLA- DRCD14CD1521 CRC and 21 healthy donorsThe expansion of peripheral GMCs correlated with higher stage and histological grade of cancer, thereby suggesting their role in cancer progression[47]
Peripheral bloodM-MDSCs were detected as CD45+CD11b+CD33+HLA- DRlowCD14+CD15, G-MDSCs (CD33hi PMN- MDSC) were detected as CD45+CD11b+CD33hiHLA- DRlowCD14CD15+10 patients with advanced colorectal carcinomaLevels of circulating M-MDSCs were not associated with metastatic disease within advanced CRC patients. Levels of circulating CD33hi PMN-MDSCs were elevated in patients with distant metastases compared to T3 M0 subgroup[52]
PBMCM-MDSCs (defined as CD14+HLA-DR–/low) PMN-MDSCs (defined as low density, CD33+CD11b+CD14 CD15+SSChi)1 CRC patient and 8 healthy donorsA significant expansion of CD38+ M-MDSCs and a trend of expansion of CD38+ PMN-MDSCs (accompanied by a trend of increased CD38 expression on both M-MDSCs and PMN-MDSCs) were observed in PBMCs of CRC patients when compared with healthy donors[54]

PBMC: peripheral blood mononuclear cell