Single-gene knockout-coupled omics analysis identifies C9orf85 and CXorf38 as two uncharacterized human proteins associated with ZIP8 malfunction.

Human transmembrane protein metal cation symporter ZIP8 (SLC39A8) is a member of the solute carrier gene family responsible for intracellular transportation of essential micronutrients, including manganese, selenium, and zinc. Previously, we established a ZIP8-knockout (KO) human cell model using the CRISPR/Cas9 system and explored how the expression of ZIP8 could possibly contribute to a wide range of human diseases. To further assess the biophysiological role of ZIP8, in the current study, we employed isobaric tags for relative and absolute quantitation (iTRAQ) and detected the changes of the proteome in ZIP8-KO cells (proteomic data are available via ProteomeXchange with identifier PXD036680). A total of 286 differentially expressed proteins (206 downregulated and 80 upregulated proteins) were detected in the ZIP8-KO cell model, and subsequent bioinformatics analyses (GO, KEGG, KOG, and PPI) were performed on these proteins. Interestingly, four "uncharacterized" proteins (proteins with unknown biological function) were identified in the differentially expressed proteins: C1orf198, C9orf85, C17orf75, and CXorf38-all of which were under-expressed in the ZIP8-KO cells. Notably, C9orf85 and CXorf38 were amongst the top-10 most downregulated proteins, and their expressions could be selectively induced by essential micronutrients. Furthermore, clinical-based bioinformatic analysis indicated that positive correlations between the gene expressions of ZIP8 and C9orf85 or CXorf38 were observed in multiple cancer types. Overall, this study reveals the proteomic landscape of cells with impaired ZIP8 and uncovers the potential relationships between essential micronutrients and uncharacterized proteins C9orf85 and CXorf38. The differentially expressed proteins identified in ZIP8-KO cells could be the potential targets for diagnosing and/or treating human ZIP8-associated diseases, including but not limited to malnutrition, viral infection, and cancers.

The Impact of ZIP8 Disease-Associated Variants G38R, C113S, G204C, and S335T on Selenium and Cadmium Accumulations: The First Characterization.

The metal cation symporter ZIP8 (SLC39A8) is a transmembrane protein that imports the essential micronutrients iron, manganese, and zinc, as well as heavy toxic metal cadmium (Cd). It has been recently suggested that selenium (Se), another essential micronutrient that has long been known for its role in human health and cancer risk, may also be transported by the ZIP8 protein. Several mutations in the ZIP8 gene are associated with the aberrant ion homeostasis of cells and can lead to human diseases. However, the intricate relationships between ZIP8 mutations, cellular Se homeostasis, and human diseases (including cancers and illnesses associated with Cd exposure) have not been explored. To further verify if ZIP8 is involved in cellular Se transportation, we first knockout (KO) the endogenous expression of ZIP8 in the HeLa cells using the CRISPR/Cas9 system. The elimination of ZIP8 expression was examined by PCR, DNA sequencing, immunoblot, and immunofluorescence analyses. Inductively coupled plasma mass spectrometry indicated that reduced uptake of Se, along with other micronutrients and Cd, was observed in the ZIP8-KO cells. In contrast, when ZIP8 was overexpressed, increased Se uptake could be detected in the ZIP8-overexpressing cells. Additionally, we found that ZIP8 with disease-associated single-point mutations G38R, G204C, and S335T, but not C113S, showed reduced Se transport ability. We then evaluated the potential of Se on Cd cytotoxicity prevention and therapy of cancers. Results indicated that Se could suppress Cd-induced cytotoxicity via decreasing the intracellular Cd transported by ZIP8, and Se exhibited excellent anticancer activity against not all but only selected cancer cell lines, under restricted experimental conditions. Moreover, clinical-based bioinformatic analyses revealed that up-regulated ZIP8 gene expression was common across multiple cancer types, and selenoproteins that were significantly co-expressed with ZIP8 in these cancers had been identified. Taken together, this study concludes that ZIP8 is an important protein in modulating cellular Se levels and provides insights into the roles of ZIP8 and Se in disease prevention and therapy.

Ubiquitin carboxyl-terminal hydrolase isozyme L1/UCHL1 suppresses epithelial-mesenchymal transition and is under-expressed in cadmium-transformed human bronchial epithelial cells.

Cadmium (Cd), a highly toxic heavy metal, is widespreadly distributed in the environment. Chronic exposure to Cd is associated with the development of several diseases including cancers. Over the decade, many researches have been carried on various models to examine the acute effects of Cd; yet, limited knowledge is known about the long-term Cd exposure, especially in the human lung cells. Previously, we showed that chronic Cd-exposed human bronchial epithelial BEAS-2B cells exhibited transformed cell properties, such as anchorage-independent growth, augmented cell migration, and epithelial-mesenchymal transition (EMT). To study these Cd-transformed cells more comprehensively, here, we further characterized their subproteomes. Overall, a total of 63 differentially expressed proteins between Cd-transformed and passage-matched control cells among the five subcellular fractions (cytoplasmic, membrane, nuclear-soluble, chromatin-bound, and cytoskeletal) were identified by mass spectrometric analysis and database searching. Interestingly, we found that the thiol protease ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1) is one of the severely downregulated proteins in the Cd-transformed cells. Notably, the EMT phenotype of Cd-transformed cells can be suppressed by forced ectopic expression of UCHL1, suggesting UCHL1 as a crucial modulator in the maintenance of the proper differentiation status in lung epithelial cells. Since EMT is considered as a critical step during malignant cell transformation, finding novel cellular targets that can antagonize this transition may lead to more efficient strategies to inhibit cancer development. Our data report for the first time that UCHL1 may play a function in the suppression of EMT in Cd-transformed human lung epithelial cells, indicating that UCHL1 might be a new therapeutic target for chronic Cd-induced carcinogenesis. Graphical abstract.

The Impact of Coilin Nonsynonymous SNP Variants E121K and V145I on Cell Growth and Cajal Body Formation: The First Characterization.

Coilin is the main component of Cajal body (CB), a membraneless organelle that is involved in the biogenesis of ribonucleoproteins and telomerase, cell cycle, and cell growth. The disruption of CBs is linked to neurodegenerative diseases and potentially cancers. The coilin gene (COIL) contains two nonsynonymous SNPs: rs116022828 (E121K) and rs61731978 (V145I). Here, we investigated for the first time the functional impacts of these coilin SNPs on CB formation, coilin subcellular localization, microtubule formation, cell growth, and coilin expression and protein structure. We revealed that both E121K and V145I mutants could disrupt CB formation and result in various patterns of subcellular localization with survival motor neuron protein. Noteworthy, many of the E121K cells showed nucleolar coilin accumulation. The microtubule regrowth and cell cycle assays indicated that the E121K cells appeared to be trapped in the S and G2/M phases of cell cycle, resulting in reduced cell proliferation. In silico protein structure prediction suggested that the E121K mutation caused greater destabilization on the coilin structure than the V145I mutation. Additionally, clinical bioinformatic analysis indicated that coilin expression levels could be a risk factor for cancer, depending on the cancer types and races.

Resveratrol Promotes Tumor Microvessel Growth via Endoglin and Extracellular Signal-Regulated Kinase Signaling Pathway and Enhances the Anticancer Efficacy of Gemcitabine against Lung Cancer.

The synergistic anticancer effect of gemcitabine (GEM) and resveratrol (RSVL) has been noted in certain cancer types. However, whether the same phenomenon would occur in lung cancer is unclear. Here, we uncovered the molecular mechanism by which RSVL enhances the anticancer effect of GEM against lung cancer cells both in vitro and in vivo. We established human lung adenocarcinoma HCC827 xenografts in nude mice and treated them with GEM and RSVL to detect their synergistic effect in vivo. Tumor tissue sections from nude mice were subjected to hematoxylin and eosin staining for blood vessel morphological observation, and immunohistochemistry was conducted to detect CD31-positive staining blood vessels. We also established the HCC827-human umbilical vein endothelial cell (HUVEC) co-culture model to observe the tubule network formation. Human angiogenesis antibody array was used to screen the angiogenesis-related proteins in RSVL-treated HCC827. RSVL suppressed the expression of endoglin (ENG) and increased tumor microvessel growth and blood perfusion into tumor. Co-treatment of RSVL and GEM led to more tumor growth suppression than treatment of GEM alone. Mechanistically, using the HCC827-HUVEC co-culture model, we showed that RSVL-suppressed ENG expression was accompanied with augmented levels of phosphorylated extracellular signal-regulated kinase (ERK) 1/2 and increased tubule network formation, which may explain why RSVL promoted tumor microvessel growth in vivo. RSVL promoted tumor microvessel growth via ENG and ERK and enhanced the anticancer efficacy of GEM. Our results suggest that intake of RSVL may be beneficial during lung cancer chemotherapy.

Lasting DNA Damage and Aberrant DNA Repair Gene Expression Profile Are Associated with Post-Chronic Cadmium Exposure in Human Bronchial Epithelial Cells.

Cadmium (Cd) is a widespread environmental pollutant and carcinogen. Although the exact mechanisms of Cd-induced carcinogenesis remain unclear, previous acute/chronic Cd exposure studies have shown that Cd exerts its cytotoxic and carcinogenic effects through multiple mechanisms, including interference with the DNA repair system. However, the effects of post-chronic Cd exposure remain unknown. Here, we establish a unique post-chronic Cd-exposed human lung cell model (the "CR0" cells) and investigate the effects of post-chronic Cd exposure on the DNA repair system. We found that the CR0 cells retained Cd-resistant property even though it was grown in Cd-free culture medium for over a year. The CR0 cells had lasting DNA damage due to reduced DNA repair capacity and an aberrant DNA repair gene expression profile. A total of 12 DNA repair genes associated with post-chronic Cd exposure were identified, and they could be potential biomarkers for identifying post-chronic Cd exposure. Clinical database analysis suggests that some of the DNA repair genes play a role in lung cancer patients with different smoking histories. Generally, CR0 cells were more sensitive to chemotherapeutic (cisplatin, gemcitabine, and vinorelbine tartrate) and DNA damaging (H2O2) agents, which may represent a double-edged sword for cancer prevention and treatment. Overall, we demonstrated for the first time that the effects of post-chronic Cd exposure on human lung cells are long-lasting and different from that of acute and chronic exposures. Findings from our study unveiled a new perspective on Cd-induced carcinogenesis-the post-chronic exposure of Cd. This study encourages the field of post-exposure research which is crucial but has long been ignored.

Cadmium telluride quantum dot-exposed human bronchial epithelial cells: a further study of the cellular response by proteomics.

Quantum dots (QDs) are luminescent nanoparticles with superior versatility. In this regard, cadmium telluride (CdTe) QDs have been widely used for various bioimaging applications. Although these nano-Cd containing particles can be capped with shells to reduce their cytotoxicity, these shells would be gradually disintegrated after a certain period of time, thereby inevitably exerting nanotoxicity. Previously, we showed that treatment of human bronchial epithelial BEAS-2B cells with uncapped CdTe QDs (520Q, 580Q and 730Q with emission maximum at 520, 580 and 730 nm, respectively) elicited dose-dependent cytotoxicity for 520Q and 580Q (<5 nm), while 730Q (>5 nm) elicited negligible cytotoxicity. In order to gain a more global perspective on the action mechanism of these nano-Cd particles, here, we further characterized the proteome response of BEAS-2B when challenged with the above QDs. Interestingly, among the three nano-Cd particles, we observed that 520Q and 580Q treatment altered the BEAS-2B proteome significantly in a very similar magnitude while 730Q has no obvious impact at all, as compared with the untreated control. Notably, the treatment of BEAS-2B with glutathione before nano-Cd particles abrogated the induction/repression of differentially expressed proteins and prevented cell death. Taken together, our findings show that uncapped CdTe nanoparticles (520Q and 580Q) induce oxidative stress in human bronchial epithelial cells, and the similarly altered protein signatures also suggest potential mitotoxicity and common cellular and detoxification responses upon exposure of lung cells to these two QDs. On the other hand, 730Q may exert a more noticeable effect after long-term exposure, but not upon transient exposure.

Epiproteome profiling of cadmium-transformed human bronchial epithelial cells by quantitative histone post-translational modification-enzyme-linked immunosorbent assay.

Cadmium (Cd), a carcinogenic toxic metal, is pervasively distributed in the soil, water and air. Chronic exposure to Cd has been correlated to lung disease development including cancers. Although many studies have been conducted to investigate the proteome response of cells challenged with Cd, the epiproteomic responses (i.e., global histone post-translational modifications [PTMs]), particularly in human lung cells, are largely unexplored. Here, we provide an epiproteome profiling of human bronchial epithelial cells (BEAS-2B) chronically treated with cadmium chloride (CdCl2 ), with the aim of identifying global epiproteomic signatures in response to Cd epigenotoxicity. Total histone proteins from Cd-treated and untreated BEAS-2B cells were isolated and subject to quantitative histone PTM-enzyme-linked immunosorbent assay using 18 histone PTM antibodies. Our results unveiled that chronic Cd treatment led to the marked downregulation of H3K4me2 and H3K36me3 and upregulation of H3K9acS10ph, H4K5ac, H4K8ac and H4K12ac PTM marks. Cd-treated cells exhibit transformed cell properties as evidenced by enhanced cell migration and the ability of anchorage-independent growth on soft agar. Notably, treatment of Cd-transformed cells with C646, a potent histone acetyltransferase inhibitor, suppressed the expression of mesenchymal marker genes and cell migration ability of these cells. Taken together, our studies provide for the first time the global epiproteomic interrogation of chronic Cd-exposed human lung cells. The identified aberrant histone PTM alterations associated with Cd-induced epigenotoxicity likely account for the epithelial-mesenchymal transition and neoplastic survival of these cells.

Acute and chronic cadmium telluride quantum dots-exposed human bronchial epithelial cells: The effects of particle sizes on their cytotoxicity and carcinogenicity.

Quantum dots (QDs) are semiconducting nanocrystals with unique optical properties. When coated with shell/capping, QDs are not deleterious to cells and organisms. However, when QDs are retained in the cellular environment for a certain period of time, their coatings may be degraded, yielding "naked" QDs. Although some studies have documented the acute effects of cadmium telluride (CdTe) QDs in various cell lines, however, to our knowledge, there are no published studies on the chronic effects of CdTe QDs in normal lung cells. In this study, we therefore sought to study the effects of CdTe QDs of various particle sizes on their cytotoxicity and carcinogenicity in normal human bronchial epithelial cells (BEAS-2B). A total of three particle sizes of CdTe QD with emission maximum at 520, 580, and 730 nm were employed (abbreviated as 520Q, 580Q, and 730Q, respectively). Our results indicated that acute exposure to 520Q (∼2.04 nm in diameter) and 580Q (∼3.24 nm in diameter) elicited dose-dependent cytotoxicity; while acute exposure to 730Q (∼5.40 nm in diameter) elicited negligible cytotoxicity in BEAS-2B cells. Notably, chronic exposure to CdTe QD of all three tested particle sizes induced BEAS-2B cell transformation as evidenced by enhanced cell migration and anchorage-independent growth on soft agar. Taken together, our findings suggest that CdTe QDs are potent human lung carcinogens.