Involvement of insulin-like growth factor binding protein-3 in the retinoic acid receptor-α-mediated inhibition of hepatocellular carcinoma cell proliferation

We examined the relationship between the expression of retinoic acid receptor-α (RAR-α) and upregulation of insulin-like growth factor binding protein-3 (IGFBP-3) in the retinoid-induced inhibition of hepatocellular carcinoma (HCC) cell proliferation. HCC cell lines showed a marked expression of RAR-α, whereas the expression levels of RAR-β and RAR-γ were relatively lower. An RAR-α agonist significantly inhibited the HCC cell proliferation both in vitro and in vivo. The RAR-α expression closely related to the upregulation of IGFBP-3 as compared with RAR-β or RAR-α expressions. RAR-α agonist would be beneficial to inhibit the growth of HCC.