Cytokine-induced Apoptosis Inhibitor Research Articles

Expression of cytokine-induced apoptosis inhibitor 1 in gastric cancer tissues and its effects on invasion and migration of SGC-7901 cell

To examine the expression of cytokine-induced apoptosis inhibitor1 (CIAPIN1) in gastric cancer and normal mucosa tissues, and to investigate its effects on migration and invasion of gastric cancer cells. Immunohistochemistry was used to detect CIAPIN1 expression in 15 samples of normal gastric mucosa tissues, 148 samples of gastric cancer tissues (42 of non-metastasis gastric cancer tissues without other organs or lymph node metastasis, 106 of metastasis gastric cancer tissues with lymph node metastasis), and 37 samples of gastric cancer lymph node metastasis tissues. Association of CIAPIN1 expression with clinicopathological characteristics of gastric cancer was analyzed by Chi-square test. SGC-7901 cell lines of high CIAPIN1 expression and low CIAPIN1 expression were established. Transwell assay was applied to detect the invasion and migration of CIAPIN1-regulated gastric cancer cells. Positive rate of CIAPIN1 expression in gastric cancer tissues was lower than that in normal gastric mucosa tissues (41.2% vs. 86.7%, P=0.0008), and in metastasis gastric cancer tissues was also lower than that in non-metastasis gastric cancer tissues (34.9% vs. 71.4%, P=0.0000). Furthermore, the positive rate of CIAPIN1 expression was closely related to the TNM staging of gastric cancer (TNM stage I(, II( and III( were 55.0%, 53.5% and 24.4%, respectively, P=0.0037). But there was no significant difference of positive expressive rate between metastatic gastric cancer tissues and metastatic lymph node tissues(34.9% vs. 21.6%, P=0.3700). Transwell assay showed that up-regulated CIAPIN1 expression would significantly reduce, while down-regulated CIAPIN1 expression would significantly promote the invasion and migration of SGC-7901 cells (all P<0.05). Positive rate of CIAPIN1 expression is low in gastric cancer tissues and shows inhibition of invasion and migration of gastric cancer cells.

Molecular cloning, expression and functional characterization of a teleostan cytokine-induced apoptosis inhibitor from rock bream (Oplegnathus fasciatus)

Apoptosis plays a key role in the physiology of multicellular organisms and is regulated by different promoting and inhibitory mechanisms. Cytokine-induced apoptotic inhibitor (CIAPI) was recently identified as a key factor involved in apoptosis inhibition in higher vertebrate lineages. However, most of the CIAPIs of lower vertebrate species are yet to be characterized. Herein, we molecularly characterized a teleostan counterpart of CIAPI from rock bream (Oplegnathus fasciatus), designating as RbCIAPI. The complete coding region of RbCIAPI was consisted of 942 nucleotides encoding a protein of 313 amino acids with a predicted molecular mass of ~33 kDa. RbCIAPI gene exhibited a multi-exonic architecture, consisting 9 exons interrupted by 8 introns. Protein sequence analysis revealed that RbCIAPI shares significant homology with known CIAPI counterparts, and phylogenetic reconstruction confirmed its closer evolutionary relationship with its fish counterparts. Ubiquitous spatial distribution of RbCIAPI was detected in our quantitative real time polymerase chain reaction (qPCR) analysis, where more prominent expression levels were observed in the blood and liver tissues. Moreover, the RbCIAPI basal transcription level was found to be modulated by different bacterial and viral stimuli, which could be plausibly supported by our previous observations on the transcriptional modulation of the caspase 3 counterpart of rock bream (Rbcasp3) in response to the same stimuli. In addition, our in vitro functional assay demonstrated that recombinant RbCIAPI could detectably inhibit the proteolysis activity of recombinant Rbcasp3. Collectively, our preliminary results suggest that RbCIAPI may play an anti-apoptotic role in rock bream physiology, likely by inhibiting the caspase-dependent apoptosis pathway. Therefore, RbCIAPI potentially plays an important role in host immunity by regulating the apoptosis process under pathogenic stress.

Cytokine-induced apoptosis inhibitor 1 inhibits the growth and proliferation of multiple myeloma.

The present study investigated the differential expression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) in human multiple myeloma (MM) bone marrow tissue and adjacent healthy bone marrow tissue. In addition, the effect of a transduced CIAPIN1 gene on the growth of the RPMI-8226 human MM cell line was investigated. CIAPIN1 protein expression was detected in 32 samples of paraffin-embedded MM and adjacent healthy bone marrow tissue using immunohistochemistry. The CIAPIN1 gene (Ad-CIAPIN1, small interfering RNA) was inserted into a lentiviral vector and transfected into the RPMI-8226 human MM cell line. The expression of target proteins CIAPIN1 and insulin-like growth factor 1 U (IGF-1), cell cycle-regulatory proteins and functional proteins was detected using western blotting. MTT and soft agar colony formation assays were conducted, and cellular tumorigenicity in nude mice was assessed, in order to investigate the proliferative capacity of cells in vitro and in vivo. Flow cytometry was applied in order to analyze changes in the cell cycle and cell apoptosis. CIAPIN1 expression was significantly reduced in cells from the 32 MM samples compared with those from healthy bone marrow (P<0.05). Upregulation of CIAPIN1, following transduction by lentiviral vectors, caused cells to arrest in G1/S phase of the cell cycle and significantly inhibited the growth of the RPMI-8226 MM cell line in vitro and in vivo. CIAPIN1 was shown to inhibit cell growth. Specifically, it inhibited cyclin-dependent kinase 2, cyclin-dependent kinase 4 and insulin-like growth factor-1. Increased expression of CIAPIN1 also led to an increase in the levels of p27 and Rb, an effect that may have been achieved via regulation of cell cycle proteins and functional proteins. The results of the present study suggest that downregulation of the CIAPIN1 gene in MM cells may be associated with the development of this disease. CIAPIN1 transfection in RPMI-8226 cells significantly inhibited the growth of tumor cells, suggesting that the CIAPIN1 gene is a potential tumor suppressor.

CIAPIN1 gene silencing enhances chemosensitivity in a drug-resistant animal model in vivo

Overexpression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) contributes to multidrug resistance (MDR) in breast cancer. This study aimed to evaluate the potential of CIAPIN1 gene silencing by RNA interference (RNAi) as a treatment for drug-resistant breast cancer and to investigate the effect of CIAPIN1 on the drug resistance of breast cancer in vivo. We used lentivirus-vector-based RNAi to knock down CIAPIN1 in nude mice bearing MDR breast cancer tumors and found that lentivirus-vector-mediated silencing of CIAPIN1 could efficiently and significantly inhibit tumor growth when combined with chemotherapy in vivo. Furthermore, Western blot analysis showed that both CIAPIN1 and P-glycoprotein expression were efficiently downregulated, and P53 was upregulated, after RNAi. Therefore, we concluded that lentivirus-vector-mediated RNAi targeting of CIAPIN1 is a potential approach to reverse MDR of breast cancer. In addition, CIAPIN1 may participate in MDR of breast cancer by regulating P-glycoprotein and P53 expression.

Drosophila CIAPIN1 homologue is required for follicle cell proliferation and survival

The conserved cytokine-induced apoptosis inhibitor-1 (CIAPIN1) gene has been implicated in several processes, such as apoptosis, cell division, angiogenesis and Fe/S protein biogenesis. In this study, we identified the Drosophila CIAPIN1 homologue (D-CIAPIN1) and studied its role in ovarian development. We found that D-CIAPIN1 is conserved as it can complement the nonviability of the yeast CIAPIN1-deletion strain. Several D-CIAPIN1 alleles were identified, including one allele in which that codon encoding the highly conserved twin cysteine CX2 C motif is mutated, demonstrating for the first time the importance of this motif to protein function. We demonstrated D-CIAPIN1 is an essential gene required for ovarian development. We found that D-CIAPIN1 female mutants are sterile, containing rudimentary ovaries. We noted a decrease in follicle cell numbers in D-CIAPIN1 mutant egg chambers. We further demonstrated that the decrease in follicle cell numbers in D-CIAPIN1 mutants is due to a reduced mitotic index and enhanced cell death. Our study reveals that D-CIAPIN1 is essential for egg chamber development and is required for follicle cell proliferation and survival.

CIAPIN1 siRNA Inhibits Proliferation, Migration and Promotes Apoptosis of VSMCs by Regulating Bcl-2 and Bax

Migration, proliferation and apoptosis of vascular smooth muscle cells (VSMCs) have recently been identified as important processes in a variety of human vascular diseases, including atherosclerosis, arterial injury, and restenosis after angioplasty. These processes are regulated by interactions between the local cell-cell and cytokine environment. Cytokine induced apoptosis inhibitor (CIAPIN1) is a novel antiapoptotic molecule and plays a vitally important role in malignant phenotypes of cancers. However, the effect of CIAPIN1 on VSMCs has not been reported. In the present study, we constructed the adenovirus encoding CIAPIN1 siRNA and transduced it into VSMCs. The results demonstrated that CIAPIN1 siRNA inhibited proliferation, migration and promotes apoptosis of VSMCs by regulating Bcl-2 and Bax. Our results suggest that CIAPIN1 siRNA might play the key role in VSMC biological function and provide the new therapeutic strategy for vascular diseases.

Molecular characterization of a cytokine-induced apoptosis inhibitor from Schistosoma japonicum

Cytokine-induced apoptosis inhibitor (CIAP) is a novel antiapoptotic molecule, which is different to inhibitor of apoptosis protein or B-cell lymphoma 2. CIAP was originally identified as a molecule that conferred resistance to apoptosis induced by growth factor starvation. However, it remains to be undercharacterized in schistosomes. Here, we molecularly characterize a novel cytokine-induced apoptosis inhibitor from Schistosoma japonicum (SjCIAP). The transcription of the SjCIAP occurred at all of developmental stages investigated including eggs, cercariae, schistosomula, and adult schistosomes. Functional assay indicated that the SjCIAP could inhibit caspase activity in either human cell lines or schistosome lysates. Our preliminary results suggest that the SjCIAP may play important roles in parasitic living and development by regulating apoptosis, and drug target of SjCIAP might be a potential for schistosomiasis control.

Down Regulation of CIAPIN1 Reverses Multidrug Resistance in Human Breast Cancer Cells by Inhibiting MDR1

Cytokine-induced apoptosis inhibitor 1 (CIAPIN1), initially named anamorsin, a newly indentified antiapoptotic molecule is a downstream effector of the receptor tyrosine kinase-Ras signaling pathway. Current study has revealed that CIAPIN1 may have wide and important functions, especially due to its close correlations with malignant tumors. However whether or not it is involved in the multi-drug resistance (MDR) process of breast cancer has not been elucidated. To explore the effect of CIAPIN1 on MDR, we examined the expression of P-gp and CIAPIN1 by immunohistochemistry and found there was positive correlation between them. Then we successfully interfered with RNA translation by the infection of siRNA of CIAPIN1 into MCF7/ADM breast cancer cell lines through a lentivirus, and the expression of the target gene was significantly inhibited. After RNAi the drug resistance was reduced significantly and the expression of MDR1mRNA and P-gp in MCF7/ADM cell lines showed a significant decrease. Also the expression of P53 protein increased in a statistically significant way (p ≤ 0.01) after RNAi exposure. In addition, flow cytometry analysis reveals that cell cycle and anti-apoptotic enhancing capability of cells changed after RNAi treatment. These results suggested CIAPIN1 may participate in breast cancer MDR by regulating MDR1 and P53 expression, changing cell cycle and enhancing the anti-apoptotic capability of cells.

CIAPIN1 nuclear accumulation predicts poor clinical outcome in epithelial ovarian cancer

BackgroundEpithelial ovarian cancer (EOC) is an aggressive disease with poor prognosis. The expression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) correlates with the malignant progression of several cancers. However, the relationship between the subcellular localization of CIAPIN1 and clinical characteristics in EOC remains unclear.MethodsImmunohistochemistry was performed to detect CIAPIN1 expression in 108 EOC tissues. CIAPIN1 expressions in eight fresh EOC tissues were detected by Western blotting. The relationship between CIAPIN1 subcellular expression and patients’ clinicopathological features, including prognosis, was evaluated. Immunohistochemistry and immunofluorescence were employed to assess the CIAPIN1 subcellular localization in the EOC cell lines A2780 and HO8910. In addition, all patients were followed up to assess the prognostic value of CIAPIN1 in patients with EOC.ResultsCIAPIN1 is highly expressed in EOC, but is present at low levels in paired non-cancerous ovarian epithelial tissues. The results of Western blotting were in accordance with the immunohistochemical results. Poor differentiation of the tumors and EOC cell lines correlated with higher levels of CIAPIN1 nuclear expression. CIAPIN1 nuclear expression significantly correlated with the Federation International of Gynecology and Obstetrics (FIGO) stage and histological differentiation (P = 0.034 and P < 0.0001, respectively). Moreover, nuclear localization of CIAPIN1 was selected as an unfavorable prognostic factor by both univariate and multivariate analyses ( P < 0.001). However, no significant correlations were observed between cytoplasmic localization of CIAPIN1 and clinicopathological parameters.ConclusionsCIAPIN1 might play a crucial role in the differentiation of EOC cells. Elevated expression of nuclear CIAPIN1 negatively correlated with the survival of EOC patients, suggesting that nuclear CIAPIN1 might serve as a prognostic biomarker for EOC patients.

A S‐adenosylmethionine methyltransferase‐like domain within the essential, Fe‐S‐containing yeast protein Dre2

Yeast Dre2 is an essential Fe-S cluster-containing protein that has been implicated in cytosolic Fe-S protein biogenesis and in cell death regulation in response to oxidative stress. Its absence in yeast can be complemented by the human homologous antiapoptotic protein cytokine-induced apoptosis inhibitor 1 (also known as anamorsin), suggesting at least one common function. Using complementary techniques, we have investigated the biochemical and biophysical properties of Dre2. We show that it contains an N-terminal domain whose structure in solution consists of a stable well-structured monomer with an overall typical S-adenosylmethionine methyltransferase fold lacking two α-helices and a β-strand. The highly conserved C-terminus of Dre2, containing two Fe-S clusters, influences the flexibility of the N-terminal domain. We discuss the hypotheses that the activity of the N-terminal domain could be modulated by the redox activity of Fe-S clusters containing the C-terminus domain in vivo.

Proteomic Analysis of Early-Responsive Redox-Sensitive Proteins in Arabidopsis

Regulation of protein function through oxidative modification has emerged as an important molecular mechanism modulating various biological processes. Here, we report a proteomic study of redox-sensitive proteins in Arabidopsis cells subjected to H2O2 treatment. Four gel-based approaches were employed, leading to the identification of four partially overlapping sets of proteins whose thiols underwent oxidative modification in the H2O2-treated cells. Using a method based on differential labeling of thiols followed by immunoprecipitation and Western blotting, five of the six selected putative redox-sensitive proteins were confirmed to undergo oxidative modification following the oxidant treatment in Arabidopsis leaves. Another method, which is based on differential labeling of thiols coupled with protein electrophoretic mobility shift assay, was adopted to reveal that one of the H2O2-sensitive proteins, a homologue of cytokine-induced apoptosis inhibitor 1 (AtCIAPIN1), also underwent oxidative modification in Arabidopsis leaves after treatments with salicylic acid or the peptide elicitor flg22, two inducers of defense signaling. The redox-sensitive proteins identified from the proteomic study are involved in various biological processes such as metabolism, the antioxidant system, protein biosynthesis and processing, and cytoskeleton organization. The identification of novel redox-sensitive proteins will be helpful toward understanding of cellular components or pathways previously unknown to be redox-regulated.

Apoptosis Governs the Elimination of Schistosoma japonicum from the Non-Permissive Host Microtus fortis

The reed vole, Microtus fortis, is the only known mammalian host in which schistosomes of Schistosoma japonicum are unable to mature and cause significant pathogenesis. However, little is known about how Schistosoma japonicum maturation (and, therefore, the development of schistosomiasis) is prevented in M. fortis. In the present study, the ultrastructure of 10 days post infection schistosomula from BALB/c mice and M. fortis were first compared using scanning electron microscopy and transmission electron microscopy. Electron microscopic investigations showed growth retardation and ultrastructural differences in the tegument and sub-tegumental tissues as well as in the parenchymal cells of schistosomula from M. fortis compared with those in BALB/c mice. Then, microarray analysis revealed significant differential expression between the schistosomula from the two rodents, with 3,293 down-regulated (by ≥2-fold) and 71 up-regulated (≥2 fold) genes in schistosomula from the former. The up-regulated genes included a proliferation-related gene encoding granulin (Grn) and tropomyosin. Genes that were down-regulated in schistosomula from M. fortis included apoptosis-inhibited genes encoding a baculoviral IAP repeat-containing protein (SjIAP) and cytokine-induced apoptosis inhibitor (SjCIAP), genes encoding molecules involved in insulin metabolism, long-chain fatty acid metabolism, signal transduction, the transforming growth factor (TGF) pathway, the Wnt pathway and in development. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) and PI/Annexin V-FITC assays, caspase 3/7 activity analysis, and flow cytometry revealed that the percentages of early apoptotic and late apoptotic and/or necrotic cells, as well as the level of caspase activity, in schistosomula from M. fortis were all significantly higher than in those from BALB/c mice.

Proteomic Profiles of Mouse Neuro N2a Cells Infected with Variant Virulence of Rabies Viruses

We characterized the proteomes of murine N2a cells following infection with three rabies virus (RV) strains, characterized by distinct virulence phenotypes (i.e., virulent BD06, fixed CVS-11, and attenuated SRV9 strains), and identified 35 changes to protein expression using two-dimensional gel electrophoresis in whole-cell lysates. The annotated functions of these proteins are involved in various cytoskeletal, signal transduction, stress response, and metabolic processes. Specifically, a-enolase, prx-4, vimentin, cytokine-induced apoptosis inhibitor 1 (CIAPIN1) and prx-6 were significantly up-regulated, whereas Trx like-1 and galectin-1 were down-regulated following infection of N2a cells with all three rabies virus strains. However, comparing expressions of all 35 proteins affected between BD06-, CVS-11-, and SRV9-infected cells, specific changes in expression were also observed. The up-regulation of vimentin, CIAPIN1, prx-4, and 14-3-3 theta/delta, and downregulation of NDPK-B and HSP-1 with CVS and SRV9 infection were ≥ 2 times greater than with BD06. Meanwhile, Zfp12 protein, splicing factor, and arginine/serine-rich 1 were unaltered in the cells infected with BD06 and CVS- 11, but were up-regulated in the group infected with SRV9. The proteomic alterations described here may suggest that these changes to protein expression correlate with the rabies virus' adaptability and virulence in N2a cells, and hence provides new clues as to the response of N2a host cells to rabies virus infections, and may also aid in uncovering new pathways in these cells that are involved in rabies infections. Further characterization of the functions of the affected proteins may contribute to our understanding of the mechanisms of RV infection and pathogenesis.

Identification of Differentially Regulated Secretome Components During Skeletal Myogenesis

Myogenesis is a well-characterized program of cellular differentiation that is exquisitely sensitive to the extracellular milieu. Systematic characterization of the myogenic secretome (i.e. the ensemble of secreted proteins) is, therefore, warranted for the identification of novel secretome components that regulate both the pluripotency of these progenitor mesenchymal cells, and also their commitment and passage through the differentiation program. Previously, we have successfully identified 26 secreted proteins in the mouse skeletal muscle cell line C2C12 (1). In an effort to attain a more comprehensive picture of the regulation of myogenesis by its extracellular milieu, quantitative profiling employing stable isotope labeling by amino acids in cell culture was implemented in conjunction with two parallel high throughput online reverse phase liquid chromatography-tandem mass spectrometry systems. In summary, 34 secreted proteins were quantified, 30 of which were shown to be differentially expressed during muscle development. Intriguingly, our analysis has revealed several novel up- and down-regulated secretome components that may have critical biological relevance for both the maintenance of pluripotency and the passage of cells through the differentiation program. In particular, the altered regulation of secretome components, including follistatin-like protein-1, osteoglycin, spondin-2, and cytokine-induced apoptosis inhibitor-1, along with constitutively expressed factors, such as fibulin-2, illustrate dynamic changes in the secretome that take place when differentiation to a specific lineage occurs.

Nuclear translocation of anamorsin during drug-induced dopaminergic neurodegeneration in culture and in rat brain

Anamorsin, also called cytokine-induced apoptosis inhibitor 1 (CIAPIN1), was recently identified to confer resistance to apoptosis induced by growth factor deprivation and to be indispensible for hematopoiesis. Recently, it was demonstrated that anamorsin is also widely distributed in both fetal and adult tissues. In this study, we evaluated the tissue distribution of anamorsin in the central nervous system (CNS) during development. In situ hybridization and immunoblot analyses revealed that anamorsin mRNA and protein were both highly and widely expressed in various regions of the CNS, including the cerebral cortex, hippocampus, midbrain, cerebellum, medulla, and spinal cord. Based on these findings, we examined its cellular localization during drug-induced neurodegeneration in MN9D dopaminergic cells. Both immunocytochemical localization and immunoblot analyses indicated that cytosolic anamorsin was translocated into the nucleus in a time-dependent manner following treatment with a reactive oxygen species (ROS)-inducing drug, 6-hydroxydopamine (6-OHDA). Treatment of cells with the apoptosis-inducing reagent, staurosporine, did not appear to cause translocation of anamorsin into the nucleus. When cells were treated with the nuclear export inhibitor, Leptomycin B, alone or with 6-OHDA, nuclear anamorsin levels increased, indicating that nuclear influx and efflux of anamorsin are regulated by 6-OHDA treatment. In rat brain injected with 6-OHDA, nuclear translocation of anamorsin was identified in certain tyrosine hydroxylase (TH)-positive neurons as well as TH-negative cells. Furthermore, treatment of MN9D cells with hydrogen peroxide or ROS-inducing trace metals caused nuclear translocation of anamorsin. Taken together, our data indicate that nuclear translocation of anamorsin is a ROS-dependent event and may participate in the regulation of transcription of critical molecules during dopaminergic neurodegeneration.

CIAPIN1 as a therapeutic target in cancer

Importance of the field: Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) is a newly identified cytokine-induced apoptosis inhibitor, which has roles in cell division and angiogenesis. Owing to its prognostic value for human tumors and involvement in cancer progression and tumor cell resistance to anticancer agents, CIAPIN1 has been proposed as an attractive target for new anticancer interventions.Areas covered in this review: We define CIAPIN1's potential function as a new therapeutic target for anticancer interventions and this review covers all related literature on CIAPIN1 in cancer from the past 5 yearsWhat the reader will gain: Several preclinical studies have demonstrated that CIAPIN1 is associated with chemotherapy resistance, increased tumor recurrence and shorter patient survival in different human tumor models, making anti-CIAPIN1 therapy an attractive cancer treatment strategy. Recent studies also suggest that CIAPIN1 is expressed at low levels in some types of malignant tumors and that its overexpression may inhibit their proliferation or tumorigenesis.Take home message: Considering that the exact expression and function of CIAPIN1 are still not well characterized and understood, better knowledge of CIAPIN1 in normal versus tumor tissues will be instrumental for the design of optimal strategies to selectively disrupt CIAPIN1 in cancer.

Downregulated expression of CIAPIN1 may contribute to gastric carcinogenesis by accelerating cell proliferation and promoting cell cycle progression

Our previous studies revealed that cytokine induced apoptosis inhibitor 1 (CIAPIN1), which was reported to be essential in mouse definitive hematopoiesis, was related to multidrug resistance in gastric cancer cells and that the distribution of CIAPIN1 in normal human tissues was similar to the distribution of Ras. This study aimed to explore whether CIAPIN1 plays a role in gastric carcinogenesis. Expression of CIAPIN1 in normal, inflammatory gastric mucosa, gastric precancerous lesions and gastric adenocarcinoma was detected by immunohistochemistry and Western blotting and, influence of CIAPIN1 on the proliferation of gastric cancer cells was investigated by ectopic expression of CIAPIN1 and RNA interference (RNAi). Our immunohistochemical results demonstrated that the expression of CIAPIN1 in gastric antral mucosa was progressively reduced along the sequence of normal/inflammatory gastric mucosa-atrophy-intestinal metaplasia-dysplasia-adenocarcinoma. The downregulation of CIAPIN1 in cancerous tissues was further confirmed by Western blotting. No relationship between the expression level of CIAPIN1 and the clinicopathological parameters such as age, gender, differentiation, TNM stage and the existence of metastasis was found in gastric cancer patients. In in vitro cellular experiments, ectopic expression of CIAPIN1 by cDNA transfection resulted in suppression of cell proliferation and inhibition of cell cycle progression while knockdown of CIAPIN1 with siRNA accelerated cell proliferation and promoted cell cycle progression in SGC7901 and MKN28 gastric cancer cells. These results suggest that downregulated CIAPIN1 expression may contribute to gastric carcinogenesis by accelerating cell proliferation and promoting cell cycle progression.

A new apoptosis inhibitor, CIAPIN1 (cytokine-induced apoptosis inhibitor 1), mediates multidrug resistance in leukemia cells by regulating MDR-1, Bcl-2, and Bax

We investigated the role of cytokine-induced apoptosis inhibitor 1 (CIAPIN1), a newly identified apoptosis inhibitor, in leukemia cell multidrug resistance (MDR) and its possible underlying mechanisms. CIAPIN1 was found to be overexpressed at the mRNA and protein levels in the vincristine-induced multidrug-resistant leukemia cell line HL-60/VCR, compared with HL-60, its parental cell line. In this study, we transfected HL-60 with a eukaryotic expression vector of CIAPIN1. In vitro drug sensitivity assays suggested that HL-60-CIAPIN1 cells conferred resistance to both P-glycoprotein (P-gp)-related and -unrelated drugs. Blocking CIAPIN1 expression in HL-60/VCR cells by CIAPIN1-specific small interfering RNA increased the cells' sensitivity to various chemotherapeutic drugs. Flow cytometry results suggested that CIAPIN1 expression could suppress adriamycin-induced apoptosis, accompanied by a decreased accumulation and increased release of adriamycin. Semiquantitative RT-PCR, Western blot analysis, and luciferase reporter assays suggested that CIAPIN1 could significantly upregulate the expression of MDR-1 and Bcl-2, the transcription of the MDR-1 gene, as well as downregulate the expression of Bax. Additionally, the inhibition of CIAPIN1 expression by RNA interference or P-gp inhibitor could partially reverse CIAPIN1-mediated MDR. Taken together, our findings suggest that downregulating CIAPIN1 could sensitize leukemia cells to chemotherapeutic drugs by downregulating MDR-1 and Bcl-2 and by upregulating Bax, yet not altering either glutathione-S-transferase activity or intracellular glutathione content in leukemia cells. Further study of CIAPIN1's function may reveal more of the mechanisms of leukemia MDR and result in the development of strategies to treat leukemia.

Subcellular Localization of CIAPIN1

Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) is a newly identified anti-apoptotic molecule. Our previous studies have demonstrated that CIAPIN1 is ubiquitously expressed in normal fetal and adult human tissues and confers multidrug resistance in gastric cancer cells, possibly by upregulating the expression of multidrug resistance gene 1 and multidrug resistance-related protein 1. However, fundamental biological functions of CIAPIN1 have not been elucidated. In this study, we first predicted the subcellular localization of CIAPIN1 with bioinformatic approaches and then characterized the intracellular localization of CIAPIN1 in both human and mouse cells by a combination of techniques including (a)immunohistochemistry and immunofluorescence, (b) His-tagged CIAPIN1 expression, and (c)subcellular fractionation and analysis of CIAPIN1 in the fractions by Western blotting. All methods produced consistent results; CIAPIN1 was localized in both the cytoplasm and the nucleus and was accumulated in the nucleolus. Bioinformatic prediction disclosed a putative nuclear localization signal and a putative nuclear export signal within both human and mouse CIAPIN1. These findings suggest that CIAPIN1 may undergo a cytoplasm-nucleus-nucleolus translocation.

CIAPIN1 confers multidrug resistance by upregulating the expression of MDR-1 and MRP-1 in gastric cancer cells

In a previous study, we observed that cytokine-induced apoptosis inhibitor 1 (CIAPIN1), a newly identified apoptosis inhibitor, was upregulated at the mRNA level in a multidrug-resistant gastric cancer cell line SGC7901/VCR. The aim of this study was to explore the role of CIAPIN1 in the development of multidrug resistance (MDR) in gastric cancer cells. Upregulation of CIAPIN1 in MDR gastric cancer cells was confirmed by semiquantitative RT-PCR and Western blotting. Using cDNA transfection and RNA interference, we successfully established stable transfectants with up-regulation (i.e. SGC7901-pCIAPIN1) or down-regulation (i.e. SGC7901-pSiCIAPIN1 and SGC7901/ADR-pSiCIAPIN1) of CIAPIN1 expression, respectively. In vitro drug sensitivity assay demonstrated that overexpression of CIAPIN1 conferred MDR in SGC7901 cells whereas downregulation of CIAPIN1 sensitized SGC7901 and SGC7901/ADR cells to anticancer drugs. CIAPIN1 protected both SGC7901 and SGC7901/ADR cells from ADR-induced apoptosis and reduced intracellular accumulation and retention of adriamycin. Moreover, expression of P-glycoprotein (P-gp or MDR-1, a product of MDR-1 gene) and MDR-related protein-1 (MRP-1) was upregulated by CIAPIN1. In addition, Western blotting revealed that CIAPIN1 decreased the expression of Bcl-2, Bax and p53. Therefore, it is concluded that CIAPIN1 confers MDR in gastric cancer cells, likely by upregulating MDR-1 and MRP-1.