Human sulfatase 1 exerts anti-tumor activity by inhibiting the AKT/ CDK4 signaling pathway in melanoma

Human sulfatase 1 (hSulf-1) has aryl sulfatase activity. It can reduce the sulfation of cell surface heparan sulfate proteoglycan (HSPG) and inhibit various growth factor receptor-mediated signaling pathways. In most cancers, hSulf-1 is inactivated, which endows cancer cells with increasesed cell proliferation and metastatic activities, inhibition of apoptosis, and decreased sensitivity to radio- and chemotherapy. In this study, we found that hSulf-1 overexpression in melanoma cells can inhibit cell proliferation and induce cell cycle arrest and apoptosis by decreasing the protein kinase B (AKT) phosphorylation and limiting CDK4 nuclear import. We further confirmed that hSulf-1 overexpression can inhibit AKT phosphorylation and CDK4 nuclear localization and retard the growth of melanoma xenograft tumors in nude mice. Overall, hSulf-1 function in melanoma cells provides an ideal molecular treatment target. An important anti-tumor mechanism of hSulf-1 operates by decreasing downstream AKT signaling pathway activity and inhibiting the nuclear import of CDK4.