Serum Levels of Cytokine-Induced Apoptosis Inhibitor 1 (CIAPIN1) as a Potential Prognostic Biomarker of Cholangiocarcinoma

The mortality rate of cholangiocarcinoma (CCA) is high since there is a lack of a non-invasive technique to accurately detect tumors at the early stage. CCA biomarkers are consistently needed for various purposes including screening, early diagnosis, prognosis and follow-up. Herein, using bioinformatic analysis of our mitochondrial proteome database of CCA tissues, we identified cytokine-induced apoptosis inhibitor 1 (CIAPIN1) as a potential prognostic biomarker for CCA. CIAPIN1 levels in the sera of 159 CCA patients and 93 healthy controls (HC) were measured using a dot blot assay. The median level ± quartile deviation of CIAPIN1 level in the sera of CCA patient group was 0.5144 ± 0.34 µg/µL, which was significantly higher than 0.2427 ± 0.09 µg/µL of the HC group (p < 0.0001). In CCA patients, higher serum CIAPIN1 level was significantly associated with lymph node metastasis (p = 0.024) and shorter overall survival time (p = 0.001, Kaplan–Meier test). Cox regression analysis showed that the serum CIAPIN1 level can be an independent prognostic indicator for the survival of CCA patients. Moreover, for the prediction of CCA prognosis, CIAPIN1 is superior to CEA, CA19-9 and ALP. In conclusion, CIAPIN1 can be a serum biomarker candidate for the poor prognosis of CCA.

MiRNA-195-5p Functions as a Tumor Suppressor and a Predictive of Poor Prognosis in Non-small Cell Lung Cancer by Directly Targeting CIAPIN1

Accumulating evidence suggests that microRNAs (miRNAs) has been proven to be a critical regulator in the tumor progression, of which miR-195-5p was reported to function as tumor suppressor in prostate cancer and oral squamous cell carcinoma. However, studies on the clinical significance and biological function of miR-195-5p in non-small cell lung cancer (NSCLC) were still unavailable. Here, we reported that the expression of miR-195-5p was decreased in NSCLC tissues and cell lines. Downregulation of miR-195-5p was significantly associated with TNM stage, tumor size and lymph node metastasis. The Kaplan-Meier survival analysis demonstrated that the survival time of NSCLC patients with high expression of miR-195-5p was longer than those with low expression during the 5-year follow up period (p = 0.0410). COX regression analysis indicated that miR-195-5p expression was an independent prognostic indicator for the survival of NSCLC patients (HR = 2.45, 95% CI: 1.53–4.63; p = 0.007). Results of functional analyses revealed that overexpression of miR-195-5p in A549 cells inhibited cell proliferation, induced cell cycle G0/G1 phase arrest and apoptosis using MTT and flow cytometry analysis. Furthermore, bioinformatics and luciferase reporter assays demonstrated that cytokine-induced apoptosis inhibitor 1 (CIAPIN1), an anti-apoptotic molecule was a direct target of miR-195-5p in NSCLC cells. Meta-analysis based on Oncomine database showed CIAPIN1 was significantly up-regulated in human lung cancer tissues. Consistently, knockdown of CIAPIN1 phenocopied the inhibitory effects of miR-195-5p overexpression in NSCLC cell function. These findings suggest that miR-195-5p could be used as a potential prognostic predictor and tumor suppressor in NSCLC.

NBP35 interacts with DRE2 in the maturation of cytosolic iron-sulphur proteins in Arabidopsis thaliana

Proteins of the cytosolic pathway for iron-sulphur (FeS) cluster assembly are conserved, except that plants lack a gene for CFD1 (Cytosolic FeS cluster Deficient 1). This poses the question of how NBP35 (Nucleotide-Binding Protein 35 kDa), the heteromeric partner of CFD1 in metazoa, functions on its own in plants. Firstly, we created viable mutant alleles of NBP35 in Arabidopsis to overcome embryo lethality of previously reported knockout mutations. RNAi knockdown lines with less than 30% NBP35 protein surprisingly showed no developmental or biochemical differences to wild-type. Substitution of Cys14 to Ala, which destabilized the N-terminal Fe4 S4 cluster in vitro, caused mild growth defects and a significant decrease in the activity of cytosolic FeS enzymes such as aconitase and aldehyde oxidases. The DNA glycosylase ROS1 was only partially decreased in activity and xanthine dehydrogenase not at all. Plants with strongly depleted NBP35 protein in combination with Cys14 to Ala substitution had distorted leaf development and decreased FeS enzyme activities. To find protein interaction partners of NBP35, a yeast-two-hybrid screen was carried out that identified NBP35 and DRE2 (Derepressed for Ribosomal protein S14 Expression). NBP35 is known to form a dimer, and DRE2 acts upstream in the cytosolic FeS protein assembly pathway. The NBP35-DRE2 interaction was not disrupted by Cys14 to Ala substitution. Our results show that NBP35 has a function in the maturation of FeS proteins that is conserved in plants, and is closely allied to the function of DRE2.

EPR studies of wild type and mutant Dre2 identify essential [2Fe--2S] and [4Fe--4S] clusters and their cysteine ligands

Yeast Dre2 (anamorsin or CIAPIN1) is an essential component for cytosolic Fe/S cluster biosynthesis. The C-terminal domain contains eight evolutionarily conserved cysteine residues, and we previously demonstrated that the yeast Dre2 overexpressed in Escherichia coli contains one binuclear ([2Fe-2S]) cluster and one tetranuclear ([4Fe-4S]) cluster. In this study, we replaced each conserved cysteine with alanine and analyzed the effects by Electron Paramagnetic Resonance. Although the C311A mutant lacked both signals, our data clearly suggest that the [2Fe-2S] cluster is ligated to Cys252, Cys263, Cys266 and Cys268, whereas the [4Fe-4S] cluster is ligated to Cys311, Cys314, Cys322 and Cys325. By simulation analysis of the C263A and C322A data, we obtained the g-values for the [4Fe-4S] cluster (g_x,y,z = 1.830, 1.947 and 2.018) and for the [2Fe-2S] cluster (g_x,y,z =1.919, 1.962 and 2.001). We also observed spin-spin interaction between the two clusters, suggesting their close proximity. Chemically reconstituted Dre2 showed air sensitivity of the [4Fe-4S] cluster converting to a [2Fe-2S] cluster. Furthermore, using a yeast shuffle strain, we demonstrated for the first time that each of the Cys Fe-S cluster ligands with the exception of C252 is essential, indicating that both Dre2 clusters are needed for cell viability.

Knock-down of CIAPIN1 sensitizes K562 chronic myeloid leukemia cells to Imatinib by regulation of cell cycle and apoptosis-associated members via NF-κB and ERK5 signaling pathway

CIAPIN1 (cytokine-induced apoptosis inhibitor 1) was recently identified as an essential downstream effector of the Ras signaling pathway. However, its potential role in regulating myeloid leukemia cells sensitivity to Imatinib remains unclear. In this study, we found depletion of CIAPIN1 inhibited proliferation and triggered more apoptosis of K562CML (chronic myeloid leukemia) cells with or without Imatinib treatment. Meanwhile, CIAPIN1 depletion decreased ERK5 phosphorylation and NF-κB activity. Importantly, treating CIAPIN1-depleted K562 cells with ERK5 signaling pathway specific inhibitor, XMD8-92, further inhibited proliferation and promoted apoptosis with or without Imatinib treatment. Treatment with the NF-κB specific inhibitor, Bay 11-7082, induced nearly the same inhibition of proliferation and promotion of apoptosis conferred by CIAPIN1 depletion as was observed with XMD8-92 treatment. Further, XMD8-92 and Bay 11-7082 synergistically inhibited proliferation and promoted apoptosis of CIAPIN1-depleted K562 cells with or without Imatinib treatment. The nude mice transplantation model was also performed to confirm the enhanced sensitivity of CIAPIN1-depleted K562 cells to Imatinib. Thus, our results provided a potential management by which CIAPIN1 knock-down might have a crucial impact on enhancing sensitivity of K562 cells to Imatinib in the therapeutic approaches, indicating that CIAPIN1 knock-down might serve as a combination with chemotherapeutical agents in leukemia diseases therapy.

CIAPIN1 targets Na⁺/H⁺ exchanger 1 to mediate MDA-MB-231 cells' metastasis through regulation of MMPs via ERK1/2 signaling pathway

Cytokine-induced antiapoptotic inhibitor 1 (CIAPIN1) was recently identified as an essential downstream effector of the Ras signaling pathway and has been confirmed to be closely associated with various malignant tumors. However, its potential role in regulating breast cancer metastasis remains unclear. Matrix metalloproteinases (MMPs) are a broad family of zinc-biding endopeptidases that participate in the extracellular matrix (ECM) degradation that accompanies cancer cell invasion, metastasis and angiogenesis. In this study, we found up-regulation of CIAPIN1 by lentiviral expression vector inhibited the migration, invasion and MMPs expression of MDA-MB-231 cells. Further, CIAPIN1 over-expression decreased NHE1 (Na(+)/H(+) exchanger 1) expression and ERK1/2 phosphorylation. Importantly, treating CIAPIN1 over-expressed MDA-MB-231 cells with the NHE1 specific inhibitor, Cariporide, further inhibited the metastatic capacity, MMPs expression and phosphorylated ERK1/2. Treatment with the MEK1 specific inhibitor, PD98059, induced nearly the same suppression of CIAPIN1 over-expression-dependent migration, invasion and MMPs expression as was observed with Cariporide. Further, Cariporide and PD98059 synergistically suppressed migration, invasion and MMPs expression of CIAPIN1 over-expressed MDA-MB-231 cells. Thus, our results revealed the mechanism by which CIAPIN1 targeted NHE1 to mediate migration and invasion of MDA-MB-231 cells through regulation of MMPs via ERK1/2 signaling pathway.

Expression of RhoGDI2 and CIAPIN1 in gastric carcinoma

AIM: To detect the expression of RhoGTPase dissociation inhibitor 2 (RhoGDI2) and cytokine-induced apoptosis inhibitor 1 (CIAPIN1) in gastric cancer and to analyze their clinical significance.

METHODS: Immunohistochemistry was used to detect the expression of RhoGDI2 and CIAPIN1 in 94 gastric cancer specimens.

RESULTS: The positive rates of RhoGDI2 and CIAPIN1 in gastric cancer were 67.02% and 77.66%, respectively. The expression of RhoGDI2 and CIAPIN1 was related to tumor differentiation, depth of invasion, lymph node metastasis, distant metastasis and TNM stage in gastric cancer. There was a positive correlation between the expression of RhoGDI2 and that of CIAPIN1.

CONCLUSION: The expression of RhoGDI2 is correlated with that of CIAPIN1 in gastric cancer. CIAPIN1 is very likely to be regulated by RhoGDI2, and functions as a downstream target gene of RhoGDI2 in tumor invasion and metastasis. Both of them may be involved in regulating the invasion and metastasis of gastric cancer.

Crystal structure of the N-terminal methyltransferase-like domain of anamorsin

Anamorsin is a recently identified molecule that inhibits apoptosis during hematopoiesis. It contains an N-terminal methyltransferase-like domain and a C-terminal Fe-S cluster motif. Not much is known about the function of the protein. To better understand the function of anamorsin, we have solved the crystal structure of the N-terminal domain at 1.8 Å resolution. Although the overall structure resembles a typical S-adenosylmethionine (SAM) dependent methyltransferase fold, it lacks one α-helix and one β-strand. As a result, the N-terminal domain as well as the full-length anamorsin did not show S-adenosyl-L-methionine (AdoMet) dependent methyltransferase activity. Structural comparisons with known AdoMet dependent methyltransferases reveals subtle differences in the SAM binding pocket that preclude the N-terminal domain from binding to AdoMet. The N-terminal methyltransferase-like domain of anamorsin probably functions as a structural scaffold to inhibit methyl transfers by out-competing other AdoMet dependant methyltransferases or acts as bait for protein-protein interactions.