Single nucleotide polymorphisms and Zn transport by nuclear ZIP11 shape cancer phenotypes in HeLa cells

Abstract

ABSTRACTZinc (Zn) is an essential micronutrient that regulates critical biological processes such as enzymatic function, gene expression, and cell signaling and provides structural stability to proteins. Under physiological conditions, Zn is a divalent cation (Zn2+) in an inactive redox state. Maintaining Zn homeostasis is essential for normal cell development and function, and any dysregulation in supply and transport can lead to pathophysiological conditions. Zn transporters, such as ZIP11, are critical regulators in Zn homeostasis. In mammals, ZIP11 belongs to the GufA subfamily of ZIP transporters and is primarily found in the nucleus and the Golgi apparatus. Our laboratory recently reported an essential role of ZIP11 in maintaining nuclear Zn levels in the cervical cancer cell line HeLa that supports various hallmark phenotypes of cancer. Genomic analysis of publicly available cervical and ovarian cancer patient datasets identified several single-nucleotide polymorphisms (SNPs) in the ZIP11 coding region that correlated with disease severity. We hypothesized that these SNPs might have potentially deleterious consequences as they are in coding regions that could affect ZIP11 function by increasing substrate accessibility, potentially enhancing the carcinogenic phenotype of HeLa cells. In addition, we identified a classic Zn-metal binding site (MBS) composed of three relevant residues which may be required for transmembrane Zn-transport, maintenance of metal homeostasis, and the carcinogenic properties of HeLa cells. To address these questions, we utilized our well-established model of stably knock down (KD)ZIP11in HeLa cells and overexpressed ZIP11 encoding single mutations corresponding to the SNPs and the MBS. Overexpression of ZIP11 encoding SNPs restored the Zn levels and the proliferation, migration, and invasive defects ofZIP11KD cells. On the other hand, cells expressing ZIP11 with single MBS mutations exhibited a phenotype similar to KD cells, suggesting that Zn transport by this transporter is necessary for establishing and maintaining carcinogenic properties. The work highlights the functional relevance of nuclear Zn transport by ZIP11 to maintain homeostasis and support carcinogenic properties in ovarian cancer cells.