Zinc dysregulation in cancers and its potential as a therapeutic target

The maintenance of cellular calcium homeostasis is associated with cellular signalling transduction and the functions of many membrane compartments, especially endoplasmic reticulum (ER) function. ER-localized proteins that serve to maintain ER and cellular calcium homeostasis in Candida albicans are still unclear. In this study, Spf1, the putative C. albicans homologue of the Saccharomyces cerevisiae ER-localized P-type calcium ATPase ScSpf1, was investigated for its roles in cellular calcium homeostasis, hyphal development and virulence. We constructed an Spf1 null mutant which showed decreased vegetative growth rate and hypersensitivity to EGTA, high-level calcium and antifungal drugs. Similar to treatments of ER stress agents, deletion of SPF1 stimulated calcium influx in the presence of FK506, resulting in an increase in cellular calcium contents, and induced expression of the calcium-dependent response elements gene CCH1, which is essential for the cell calcium survival pathway. Moreover, the spf1 null mutant had defects in hyphal development and biofilm formation, and was severely attenuated in virulence. These findings provided phenotypic evidence supporting roles for Spf1 in the maintenance of cellular calcium homeostasis, ER stress responses, hyphal development, biofilm formation and virulence in C. albicans.

Exposure to airborne PM 2.5 suppresses microRNA expression and deregulates target oncogenes that cause neoplastic transformation in NIH3T3 cells Exposure to airborne PM2.5 suppresses microRNA expression and deregulates target oncogenes that cause neoplastic transformation in NIH3T3 cells

Background & Aims A common variant in the solute carrier family 39 member 6 gene (SLC39A6) has been associated with survival times of patients with esophageal squamous cell carcinoma (ESCC). We investigated the function of SLC39A6 and ways in which this variant affects tumor progression by studying ESCC samples and cell lines. Methods SLC39A6 was expressed or knocked down by expression of short hairpin RNAs in ESCC cells (KYSE30 and KYSE450) and HeLa cells using lentiviral vectors; we analyzed effects on proliferation, colony formation, migration, and invasion in vitro. Cells were grown as xenograft tumors in nude mice and tumor volume and metastases were quantified; tumors were collected and analyzed histologically. Cells were also analyzed for levels of intracellular zinc and messenger RNA (mRNA) expression patterns. We obtained ESCC and adjacent normal esophageal tissues from 94 patients who underwent esophagectomy in China from 2010 through 2014. Survival times of patients were measured from the date of diagnosis to the date of last follow-up or death. We sequenced mRNAs and compared levels between tumor and non-tumor tissues using the Wilcox rank-sum test. Total proteins in cell lines or tissue samples were measured by immunoblotting. We searched publicly available databases for variants of SLC39A6 in human tumor and non-tumor tissues. Results Knockdown of SLC39A6 reduced proliferation of ESCC cells in culture and metastasis of xenograft tumors in mice. Cells that overexpressed SLC39A6 had significant increases in intracellular levels of zinc and were more invasive in assays, activating phosphatidylinositol 3-kinase signaling to AKT serine/threonine kinase 1 and mitogen-activated protein kinase 1. Cells that overexpressed SLC39A6 had increased expression of mRNAs and proteins associated with metastasis, such as matrix metalloproteinase (MMP) 1, MMP3, MYC, and snail family transcriptional repressor 2 (SNAI2 or SLUG). Levels of MMP1, MMP3, MYC, and SLUG mRNAs correlated with levels of SLC39A6 mRNA in ESCC samples from patients. ESCC tissues had increased levels of SLC39A6 mRNA compared with non-tumor tissues; the increase correlated with tumor metastasis to lymph node and reduced patient survival time. Conclusions In an analysis of ESCC samples and cell lines, we associated increased expression of SLC39A6 with tumor invasiveness, intracellular level of zinc, and patient survival time. ESCC cell lines that overexpress SLC39A6 up-regulate expression MMP1, MMP3, MYC, and SLUG and form metastatic xenograft tumors in mice. Up-regulation of SLC39A6 might be used to determine prognoses of patients with ESCC or as a therapeutic target.