Suppressive expression of CD274 increases tumorigenesis and cancer stem cell phenotypes in cholangiocarcinoma.
Bottom Line: Furthermore, the CD274(low) cells possess several CSC-related characteristics, such as high aldehyde dehydrogenase (ALDH) activity, reduced reactive oxygen species production and a dormant state in the cell cycle.Furthermore, depletion of CD274 expression by shRNA in RBE cells enhances their tumorigenicity and increases ALDH activity.These results strongly suggest that CD274 has a novel function in the negative regulation of CSC-related phenotypes in human cholangiocarcinoma, which is distinct from its immunomodulatory actions.
Affiliation: Division of Cancer Biology and Therapeutics, Miyagi Cancer Center Research Institute, Natori, Japan; Department of Cancer Science, Tohoku University Graduate School of Medicine, Sendai, Japan.Show MeSH
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Mentions: We then investigated the CSC-related characteristics of the CD274low and CD274high populations derived from RBE and HuCCT1 cells. They were sorted by anti-CD274 antibody staining and the resulting populations were assessed for ALDH activity using the Aldefluor assay system followed by FACS analysis. The RBE CD274low population was 46.1% ALDH+, whereas the RBE CD274high population was 10.2% ALDH+ (Fig.2a). The HuCCT1 CD274low and CD274high populations showed 52.4% and 38.3% ALDH+, respectively. We then measured the retinal metabolism in vitro, because ALDH metabolizes all-trans retinals to all-trans retinoic acids. The level of retinoic acids produced by the CD274low population was significantly higher than that produced by the CD274high population (Fig.2c,d) in both RBE and HuCCT1 cells. These results are compatible with those of the Aldefluor assay. The CD274low and CD274high populations were further assessed for ROS levels. The ROS levels were significantly lower in the CD274low populations than in the CD274high populations derived from both RBE and HuCCT1 cells (Fig.2e,f). These results indicate that the CD274low populations of both cholangiocarcinoma cell lines predominantly exhibit CSC-related characteristics such as high ALDH1 activity and low ROS production.
Affiliation: Division of Cancer Biology and Therapeutics, Miyagi Cancer Center Research Institute, Natori, Japan; Department of Cancer Science, Tohoku University Graduate School of Medicine, Sendai, Japan.