The involvement of iron in chemerin induced cell cycle arrest in human hepatic carcinoma SMMC7721 cells

Chemerin exhibits a tumor-inhibitory role in hepatocellular carcinoma. However, the effect of chemerin on essential metal elements in hepatic cells remains unclear. In our study, the contents of six important metal ions, including potassium, calcium, sodium, magnesium, iron and zinc, were detected in human hepatoma SMMC7721 and immortal hepatic QSG7701 cells by ICP-AES. The data showed that chemerin only decreases the content of intracellular iron in SMMC7721 cells. The reduction was due to the blockage of iron entry through the decrease in the mRNA levels of divalent metal transporter 1, iron regulatory proteins and transferrin receptors. Furthermore, the reduction of the cellular iron content induced alterations of p53–p27–p21 signaling to arrest the cell cycle at S phase in SMMC7721 cells treated by chemerin. Conversely, iron addition led to recovery from the inhibitory effect of chemerin on SMMC7721 cells. The results suggest that chemerin plays an important role in inhibiting the cell proliferation of hepatocellular carcinomas by interfering with cellular iron homeostasis in this type of tumors.