A novel basement membrane-induced gene identified in the human endometrial adenocarcinoma cell line HEC1B

Icb-1 expression inhibits growth and fulvestrant response of breast cancer cells and affects survival of breast cancer patients

PURPOSE

Human gene icb-1 recently has been reported to be part of a gene expression score predicting response to antiestrogen fulvestrant in breast cancer patients. In the present study, we examined to what extent icb-1 expression would affect the response of breast cancer cells to this antiestrogen in vitro and investigated underlying molecular mechanisms. Using open access mRNA data, we elucidated the significance of icb-1 expression for survival of breast cancer patients.

METHODS

Icb-1 gene expression was knocked down by RNAi. Breast cancer cell growth after treatment with fulvestrant was assessed using the Cell Titer Blue assay. Gene expression was analyzed by Western blot analysis or RT-qPCR. Survival analyses were performed using bioinformatical online tools and data.

RESULTS

Knockdown of icb-1 in T-47D breast cancer cells significantly increased growth of this cell line and also elevated the growth-stimulatory effect of E2 (p < 0.001). After treatment with different concentrations of fulvestrant, icb-1 knockdown cells exhibited a significantly enhanced response to this drug (p < 0.01). On the molecular level, icb-1 knockdown led to elevated expression of ESR1 and its target gene TFF1 (pS2) and enhanced E2-triggered up-regulation of proliferation genes. Finally, bioinformatical meta-analysis of gene expression data of 3951 breast cancer patients revealed that high icb-1 expression increases their relapse-free survival (HR = 0.87, p < 0.05).

CONCLUSION

The presented data further support a tumor-suppressive role of icb-1 in breast cancer and suggest an inhibitory effect of this gene on fulvestrant action, which both are suggested to be mediated by suppression of cellular E2 response.

cDNA expression library screening revealed novel functional genes involved in clear cell carcinogenesis of the ovary in vitro

In order to identify genes involved in the pathogenesis of clear cell carcinoma of the ovary (CCC), functional screening using a cDNA expression library was performed. We extracted mRNA from a CCC cell line (RMG-1), established a cDNA library using a retroviral vector, transfected that library into mouse NIH3T3 cells and sequenced the resultant foci. The tissue-type specific expression of isolated genes and their transforming activities were evaluated. Seven genes were isolated. Of these genes, the mRNA expression of SEC61B and DVL1 is significantly stronger in CCC than in other histological types (p < .05). Immunohistochemical staining reveals the stronger expression of SEC61B and C1ORF38 than normal ovarian tissues (p < .05). Focus formation is confirmed by the transfection of SEC61B, C1ORF38, and DVL1 into NIH3T3 cells. The present study identified novel genes including SEC61B, C1ORF38, and DVL1, involved in the pathogenesis of CCC. These genes may be additional therapeutic targets for CCC.Impact statementWhat is already known on this subject? Several important genetic abnormalities, including ARID1A and PIK3CA mutations, have been reported in ovarian clear cell carcinoma (CCC).What the results of this study add? SEC61B, C1ORF38, and DVL1 were newly detected as candidate genes involved in ovarian clear cell carcinogenesis.What the implications are of these findings for clinical practice and/or further research? Functional screening using a cDNA expression library may be a useful technique to identify functional genes for pathogenesis. The information obtained using this technique may provide new therapeutic targets of CCC.

Vitamin D and Endometrium: A Systematic Review of a Neglected Area of Research

Growing evidence supports a role of vitamin D (VD) in reproductive health. Vitamin D receptor (VDR) is expressed in the ovary, endometrium, and myometrium. The biological actions of VD in fertility and reproductive tissues have been investigated but mainly using animal models. Conversely, the molecular data addressing the mechanisms underlying VD action in the physiologic endometrium and in endometrial pathologies are still scant. Levels of VDR expression according to the menstrual cycle are yet to be definitively clarified, possibly being lower in the proliferative compared to the secretory phase and in mid-secretory compared to early secretory phase. Endometrial tissue also expresses the enzymes involved in the metabolism of VD. The potential anti-proliferative and anti-inflammatory effects of VD for the treatment of endometriosis have been investigated in recent years. Treatment of ectopic endometrial cells with 1,25(OH)₂D₃ could significantly reduce cytokine-mediated inflammatory responses. An alteration of VD metabolism in terms of increased 24-hydroxylase mRNA and protein expression has been demonstrated in endometrial cancer, albeit not consistently. The effect of the active form of the vitamin as an anti-proliferative, pro-apoptotic, anti-inflammatory, and differentiation-inducing agent has been demonstrated in various endometrial cancer cell lines.

Icb-1 gene polymorphism rs1467465 is associated with susceptibility to ovarian cancer

In this study, we tested the hypothesis that single nucleotide polymorphisms (SNPs) of differentiation-associated human gene icb-1 (C1orf38) may be associated with ovarian cancer susceptibility. For this purpose, we compared the genotype and allele frequencies of the SNPs rs1467465 and rs12048235 in a group of 184 ovarian cancer patients with a control group of 184 age- and gender-matched women without any malignancy. Genotype-phenotype association revealed that A allele of SNP rs1467465 was more frequent in ovarian cancer patients than in the control group (0.40 vs. 0.33, OR 1.37, 95% CI 1.013-1.853, p = 0.04). After analysis of allele positivity we observed that A-positive genotypes were more frequent in the ovarian cancer group (0.65 vs. 0.53, OR 1.63, 95% CI 1.072-2.483, p = 0.02). Furthermore, the heterozygous genotype of rs1467465 was found to be more frequent in the patients group (0.50 vs. 0.41, OR 1.63, 95% CI 1.045-2.045, p = 0.03). No significant results were obtained with regard to SNP rs1204823. Our data suggest, that SNP rs1467465 of human gene icb-1 might affect susceptibility to ovarian cancer.

icb-1 Gene counteracts growth of ovarian cancer cell lines

Human gene icb-1 has been originally identified to be involved in differentiation processes of cancer cells. To examine the function of icb-1 in ovarian cancer, we knocked down its expression in three ovarian cancer cell lines and performed microarray-based gene expression profiling with subsequent gene network modeling. Loss of icb-1 expression accelerated proliferation of SK-OV-3, OVCAR-3 and OAW-42 cells and led to upregulation of ovarian cancer biomarkers like KLK10 and CLDN16. Most of the upregulated genes were part of oncogenic pathways regulated by ERα or TNF. Our data suggest that icb-1 gene inhibits growth and progression of ovarian cancer cells.

Network analysis of icb-1 gene function in human breast cancer cells

Icb-1 is a human gene previously described by our group to exert important functions in cancer cells of different origin. We now performed microarray-based gene expression profiling with subsequent network modeling to further elucidate the role of icb-1 in breast cancer cells. Analyzing the effect of icb-1 knockdown on the transcriptome of MCF-7 cells, we found 151 differentially expressed genes exhibiting more than twofold changes, 97 of which were up- and 54 downregulated. Most of the upregulated genes were cancer-related genes associated with poor prognosis, invasion and metastasis, building an oncogenic network of TNF target genes. On the other hand, network analysis identified the downregulated genes to be primarily involved in interferon signaling and cellular apoptosis. Confirming these network data, we observed that cells with reduced levels of icb-1 exhibited an impaired response to the apoptosis inducers tamoxifen, staurosporine, actinomycin, and camptothecin. The data of this study suggest that icb-1 might exert a tumor-suppressor function in breast cancer and that its loss might confer relative resistance of breast cancer cells to apoptotic drugs.

Issues to be considered when studying cancer in vitro

Various cancer treatment approaches have shown promising results when tested preclinically. The results of clinical trials, however, are often disappointing. While searching for the reasons responsible for their failures, the relevance of experimental and preclinical models has to be taken into account. Possible factors that should be considered, including cell modifications during in vitro cultivation, lack of both the relevant interactions and the structural context in vitro have been summarized in the present review.

Themis2/ICB1 is a signaling scaffold that selectively regulates macrophage Toll-like receptor signaling and cytokine production

Background

Thymocyte expressed molecule involved in selection 1 (Themis1, SwissProt accession number Q8BGW0) is the recently characterised founder member of a novel family of proteins. A second member of this family, Themis2 (Q91YX0), also known as ICB1 (Induced on contact with basement membrane 1), remains unreported at the protein level despite microarray and EST databases reporting Themis2 mRNA expression in B cells and macrophages.

Methodology/Principal Findings

Here we characterise Themis2 protein for the first time and show that it acts as a macrophage signalling scaffold, exerting a receptor-, mediator- and signalling pathway-specific effect on TLR responses in RAW 264.7 macrophages. Themis2 over-expression enhanced the LPS-induced production of TNF but not IL-6 or Cox-2, nor TNF production induced by ligands for TLR2 (PAM3) or TLR3 (poly I∶C). Moreover, LPS-induced activation of the MAP kinases ERK and p38 was enhanced in cells over-expressing Themis2 whereas the activation of JNK, IRF3 or NF-κB p65, was unaffected. Depletion of Themis2 protein by RNA inteference inhibited LPS-induced TNF production in primary human macrophages demonstrating a requirement for Themis2 in this event. Themis2 was inducibly tyrosine phosphorylated upon LPS challenge and interacted with Lyn kinase (P25911), the Rho guanine nucleotide exchange factor, Vav (P27870), and the adaptor protein Grb2 (Q60631). Mutation of either tyrosine 660 or a proline-rich sequence (PPPRPPK) simultaneously interrupted this complex and reduced by approximately 50% the capacity of Themis2 to promote LPS-induced TNF production. Finally, Themis2 protein expression was induced during macrophage development from murine bone marrow precursors and was regulated by inflammatory stimuli both in vitro and in vivo.

Conclusions/Significance

We hypothesise that Themis2 may constitute a novel, physiological control point in macrophage inflammatory responses.

Icb-1 Gene expression is elevated in human endometrial adenocarcinoma and is closely associated with HER2 expression

Human gene icb-1 (C1orf38) has been initially cloned by our group from endometrial adenocarcinoma cells. In this study, we examined icb-1 expression in 90 endometrial cancer and normal endometrial tissue specimens. Expression of icb-1 was significantly (about 3.5-fold) higher in endometrial cancer than in normal endometrium (p <.0001). Determination of various molecular markers revealed that only Ki-67 expression differed between both groups in a similarly significant manner. Furthermore, we observed a highly significant positive correlation of icb-1 transcript levels with c-erbB2 (HER2) expression (p <.0001). Our data strongly encourage further studies on the function of icb-1 in endometrial cancer.

Themis controls thymocyte selection through regulation of T cell antigen receptor-mediated signaling

Themis (thymocyte-expressed molecule involved in selection), a member of a family of proteins with unknown functions, is highly conserved among vertebrates. Here we found that Themis had high expression in thymocytes between the pre-T cell antigen receptor (pre-TCR) and positive-selection checkpoints and low expression in mature T cells. Themis-deficient thymocytes showed defective positive selection, which resulted in fewer mature thymocytes. Negative selection was also impaired in Themis-deficient mice. A greater percentage of Themis-deficient T cells had CD4(+)CD25(+)Foxp3(+) regulatory and CD62L(lo)CD44(hi) memory phenotypes than did wild-type T cells. In support of the idea that Themis is involved in TCR signaling, this protein was phosphorylated quickly after TCR stimulation and was needed for optimal TCR-driven calcium mobilization and activation of the kinase Erk.

Single nucleotide polymorphisms in human gene icb-1 and breast cancer susceptibility

In this study, we tested the hypothesis that single nucleotide polymorphisms (SNPs) of differentiation-associated human gene icb-1 (C1orf38) may be associated with breast cancer susceptibility. A total of 646 women--323 breast cancer cases and just as many controls--were included. Breast cancer patients more frequently carried the homozygous genotype AA of SNP rs1467465 than did healthy women. Analysis of allele positivity revealed that AG or GG genotypes were significantly less frequent in breast cancer patients, suggesting that presence of G allele might have protective effects. Our data suggest that SNP rs1467465 of human gene icb-1 might affect breast cancer susceptibility.

Expression of differentiation-associated gene icb-1 is estrogen-responsive in ovarian and breast cancer cell lines

icb-1 (C1orf38) is a human gene initially described by our group to be upregulated during in vitro differentiation processes of endometrial adenocarcinoma and leukemia cells triggered by different stimuli. We now report presence of a putative imperfect estrogen response element (ERE) in the promoter of icb-1 gene. Given that estrogens are known to regulate cellular differentiation processes of hormone-dependent tissues, we studied whether expression of icb-1 would be regulated by 17-beta (beta) estradiol in breast and ovarian cancer cells. As examined by means of real time PCR, treatment with 17-beta estradiol for at least 24h resulted in a significant increase of icb-1 transcript levels in ERalpha-positive MCF-7 breast cancer and OVCAR-3 ovarian cancer cells, but not in ERalpha-negative SK-BR-3 and SK-OV-3 cells. Upregulation of icb-1 transcript levels was also observed after treatment with specific ERalpha-agonist PPT and was inhibited by co-treatment with pure antiestrogen ICI 182,780 in MCF-7 and OVCAR-3 ovarian cancer cells. Treatment with cycloheximide totally inhibited estrogen effects suggesting that activation of icb-1 gene expression is no ERE-dependent early response but a secondary event requiring protein synthesis. The results of this study demonstrate that transcript levels of differentiation-associated gene icb-1 are estrogen-responsive in breast and ovarian cancer cells in an ERalpha-dependent manner. Whether icb-1 is a mediator of estrogen-triggered cellular differentiation processes has to be determined in further studies.

Expression of icb-1 gene is interferon-gamma inducible in breast and ovarian cancer cell lines and affects the IFNγ-response of SK-OV-3 ovarian cancer cells

Icb-1 (C1orf38) is a human gene initially described to be involved in in vitro differentiation processes of endometrial adenocarcinoma and leukemia cells. In this study, we examined the effect of interferon-gamma on icb-1alpha and beta mRNA levels in human cell lines derived from breast cancer and gynecological malignancies. Furthermore, we intended to approach icb-1 gene function by means of RNA interference (RNAi) to analyze the effect of an icb-1 knockdown on human cancer cells in vitro. Three breast cancer cell lines (MCF-7, SK-BR-3, MDA-MB-231), three ovarian cancer cell lines (SK-OV-3, OVCAR-3 and BG-1) and the endometrial adenocarcinoma cell line HEC-1-A were treated with interferon gamma and the transcript levels of icb-1 isoforms alpha and beta were assessed by means of semiquantitative real-time RT-PCR. Our data demonstrates an interferon-gamma triggered upregulation of icb-1alpha mRNA levels in all breast cancer cell lines and an increase of icb-1beta mRNA in MDA-MB-231 cells. The strongest (about 10-fold) increase of icb-1alpha and beta mRNA after treatment with interferon-gamma was observed in ovarian cancer cell line SK-OV-3. Additionally, our data demonstrates the success of a siRNA-mediated knockdown of icb-1alpha and beta mRNA levels, which resulted in a significant increase of the antiproliferative interferon-gamma effect on SK-OV-3 cells. In conclusion, we report identification of the novel interferon-gamma inducible gene icb-1 which is able to affect the response of ovarian cancer cells to this cytokine.

Detection of increased icb-1 transcript levels in maturing HL-60 cells: a novel marker for granulocytic and monocytic in vitro differentiation

Human gene icb-1 was initially described as a gene with increased expression in endometrial tumor cells differentiated in vitro by culture on a reconstituted basement membrane. We provide evidence for a more general involvement of icb-1 gene function in cellular differentiation processes. We report the up-regulation of icb-1 transcript levels in HL-60 promyelocytic leukemia cells during their in vitro differentiation induced by all-trans retinoic acid, vitamin D(3) or DMSO. Increased icb-1 mRNA levels could be observed both in monocytic and granulocytic differentiation. We also report the identification of the novel icb-1 splice variants icb-1beta and gamma, and the spleen-specific isoform icb-1delta. Expression of icb-1 can be used as a novel marker for in vitro differentiation processes of HL-60 cells.

Comparison of gene expression patterns induced by treatment of human umbilical vein endothelial cells with IFN-alpha 2b vs. IFN-beta 1a: understanding the functional relationship between distinct type I interferons that act through a common receptor

We analyzed whether interferon-alpha 2b (IFN-alpha 2b) and IFN-beta 1a engage their common receptor to generate activated receptor complexes possessing distinct signaling properties. Human vascular endothelial cells (HUVEC) are 100-1000-fold more sensitive to IFN-beta 1a than to IFN-alpha 2b in in vitro assays. An nonarray-based expression profiling (GeneCalling) technology was employed to compare the patterns and levels of gene expression induced by these IFN as the broadest means by which signaling events could be measured. To distinguish subtype-related differences from dose-related effects, RNA was prepared from HUVEC treated with 50-5000 pg/ml of each IFN. The results showed that at 50 pg/ml IFN, only a subset of the genes induced by IFN-beta 1a were also induced by IFN-alpha 2b and that individual genes were induced to higher levels by IFN-beta 1a. In contrast, at 5000 pg/ml, both subtypes induced essentially identical sets of genes to similar levels of expression. No genes were seen to be induced uniquely by IFN-alpha 2b but not by IFN-beta 1a. The results show that the two IFN are intrinsically capable of inducing similar gene induction responses and do not provide evidence that they generate activated receptor complexes possessing distinct signaling properties. In contrast, the two IFN generate gene induction patterns that are both qualitatively and quantitatively distinct at subsaturating and potentially physiologically more relevant concentrations.

Expression of l-3-phosphoserine phosphatase is regulated by reconstituted basement membrane

Reconstituted basement membrane (Matrigel) promotes differentiation of endometrial adenocarcinoma cells in vitro. However, little is known about the molecular basis of these in vitro differentiation processes. Using differential display RT-PCR to search for potential molecular markers we screened for genes which respond to contact to basement membrane by alteration of expression levels. Here we report that the cDNA MT32 represents an mRNA with a time dependent biphasic response pattern to contact to basement membrane. Characterizing MT32 revealed that the sequence of MT32 is identical to l-3-phosphoserine phosphatase. PCR analysis of l-3-phosphoserine phosphatase expression surprisingly revealed at least three variants of this enzyme. In summary, and in view of the literature, l-3-phosphoserine phosphatase and potential variants or family members represent molecular markers to study regulation of gene expression by components of the extracellular matrix. In conclusion, l-3-phosphoserine phosphatase(s) may be important in endometrial carcinogenesis since this enzyme synthesizes important metabolic intermediates which serve both as building blocks for peptide synthesis and for signal transducing molecules.