Expression of EBAG9/RCAS1 is associated with advanced disease in human epithelial ovarian cancer

The roles of exosomal immune checkpoint proteins in tumors

Targeting immune checkpoints has achieved great therapeutic effects in the treatment of early-stage tumors. However, most patients develop adaptive resistance to this therapy. The latest evidence demonstrates that tumor-derived exosomes may play a key role in systemic immune suppression and tumor progression. In this article, we highlight the role of exosomal immune checkpoint proteins in tumor immunity, with an emphasis on programmed death ligand 1 (PD-L1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), as well as emerging evidence on roles of T cell immunoglobulin-3 (TIM-3), arginase 1 (ARG1), and estrogen receptor binding fragment-associated antigen 9 (EBAG9) expressed by exosomes.

Transcriptome sequencing identifies genes associated with invasion of ovarian cancer

OBJECTIVE

To identify key genes in ovarian cancer using transcriptome sequencing in two cell lines: MCV152 (benign ovarian epithelial tumour) and SKOV-3 (ovarian serous carcinoma).

METHODS

Differentially expressed genes (DEGs) between SKOV-3 and MCV152 were identified. Candidate genes were assessed for enrichment in gene ontology function and Kyoto Encyclopaedia of Genes and Genomes pathway. Candidate gene expression in SKOV-3 and MCV152 cells was validated using Western blots.

RESULTS

A total of 2020 upregulated and 1673 downregulated DEGs between SKOV3 and MCV152 cells were identified that were significantly enriched in the cell adhesion function. Upregulated DEGs, such as angiopoietin 2 (ANGPT2), CD19 molecule (CD19), collagen type IV alpha 3 chain (COL4A3), fibroblast growth factor 18 (FGF18), integrin subunit beta 4 (ITGB4), integrin subunit beta 8 (ITGB8), laminin subunit alpha 3 (LAMA3), laminin subunit gamma 2 (LAMC2), protein phosphatase 2 regulatory subunit Bgamma (PPP2R2C) and spleen associated tyrosine kinase (SYK) were significantly involved in the extracellular matrix-receptor interaction pathway. Downregulated DEGs, such as AKT serine/threonine kinase 3 (AKT3), collagen type VI alpha 1 chain (COL6A1), colony stimulating factor 3 (CSF3), fibroblast growth factor 1 (FGF1), integrin subunit alpha 2 (ITGA2), integrin subunit alpha 11 (ITGA11), MYB proto-oncogene, transcription factor (MYB), phosphoenolpyruvate carboxykinase 2, mitochondrial (PCK2), placental growth factor (PGF), phosphoinositide-3-kinase adaptor protein 1 (PIK3AP1), serum/glucocorticoid regulated kinase 1 (SGK1), toll like receptor 4 (TLR4) and tumour protein p53 (TP53) were involved in PI3K-Akt signalling. Expression of these DEGs was confirmed by Western blot analyses.

CONCLUSION

Candidate genes enriched in cell adhesion, extracellular matrix-receptor interaction and PI3K-Akt signalling pathways were identified that may be closely associated with ovarian cancer invasion and potential targets for ovarian cancer treatment.

Prediction of response to anti-cancer drugs becomes robust via network integration of molecular data

Despite the widening range of high-throughput platforms and exponential growth of generated data volume, the validation of biomarkers discovered from large-scale data remains a challenging field. In order to tackle cancer heterogeneity and comply with the data dimensionality, a number of network and pathway approaches were invented but rarely systematically applied to this task. We propose a new method, called NEAmarker, for finding sensitive and robust biomarkers at the pathway level. scores from network enrichment analysis transform the original space of altered genes into a lower-dimensional space of pathways. These dimensions are then correlated with phenotype variables. The method was first tested using in vitro data from three anti-cancer drug screens and then on clinical data of The Cancer Genome Atlas. It proved superior to the single-gene and alternative enrichment analyses in terms of (1) universal applicability to different data types with a possibility of cross-platform integration, (2) consistency of the discovered correlates between independent drug screens, and (3) ability to explain differential survival of treated patients. Our new screen of anti-cancer compounds validated the performance of multivariate models of drug sensitivity. The previously proposed methods of enrichment analysis could achieve comparable levels of performance in certain tests. However, only our method could discover predictors of both in vitro response and patient survival given administration of the same drug.

Extracellular vesicle-mediated EBAG9 transfer from cancer cells to tumor microenvironment promotes immune escape and tumor progression

The antitumor immune response is a critical defense system that eliminates malignant cells. The failure of the system results in immune escape and proceeds to tumor growth. We have previously showed that estrogen receptor-binding fragment-associated antigen 9 (EBAG9) is a relevant cancer biomarker and facilities immune escape of cancers from the immune surveillance. EBAG9 in cancer cells suppresses T-cell infiltration into tumor in vivo, whereas that in host immune cells functions as a limiter for T-cell cytotoxicity. Considering that EBAG9 plays immune suppressive roles in both tumor and microenvironment, we here questioned whether EBAG9 is a transferable protein from cancer to surrounding T cells and affects antitumor immune response. In this study, we showed that spontaneous development of prostate cancer was repressed in a model of Ebag9 knockout mice crossed with transgenic adenocarcinoma of the mouse prostate (TRAMP) mice. We identified TM9SF1 as a collaborative EBAG9 interactor, which regulates epithelial-mesenchymal transition (EMT) in cancer cells. Notably, extracellular vesicles (EVs) from EBAG9-overexpressing prostate cancer cells have a potential to facilitate immune escape of tumors by inhibiting T-cell cytotoxicity and modulating immune-related gene expression in T cells. Furthermore, we showed that a neutralizing antibody for EBAG9 could rescue the EV-mediated immune suppression by recovering T-cell cytotoxicity. In addition to its autocrine functions in cancer cells, EBAG9 could behave as a new class of immune checkpoint that suppresses tumor immunity in a secretory manner. We propose that EBAG9-targeting cancer treatment could be alternative therapeutic options for advanced diseases, particularly for those with EBAG9 overexpression.

Cisplatin-, Doxorubicin-, and Docetaxel-Induced Cell Death Promoted by the Aqueous Extract of Solanum nigrum in Human Ovarian Carcinoma Cells

Chemotherapy is a major clinical treatment for managing patients with advanced and recurrent ovarian cancer. However, the clinical performance of chemotherapy is limited, and adverse effects have been observed. Integrating chemotherapy with current chemotherapeutic drugs and novel antitumor ingredients might improve the clinical performance of current chemotherapy for ovarian cancer. The aqueous extract of Solanum nigrum leaves (AE-SN), a key ingredient in many traditional Chinese medicine formulae, has exhibited tumor suppression efficacy in numerous human cancer cells but not in ovarian cancer cells. In this study, tumor suppression efficacy was determined using the ES-2, SKOV-3, and OVCAR-3 human ovarian cancer cell lines. The half-maximal inhibitory concentrations of the AE-SN in ES-2 and SKOV-3 cells were 1.052 and 1.779 mg/mL, respectively. AE-SN treatment increased the accumulation of mammalian microtubule-associated protein 1 light chain 3 A/B, an autophagic cell marker, in all the tested cell lines; however, it activated the cleavage of caspase-3, an apoptotic marker, only in SKOV-3 cells. Furthermore, the AE-SN also promoted tumor suppression efficiency of cisplatin, doxorubicin, and docetaxel in the tested ovarian cancer cells. In addition, AE-SN-enhanced cell death was associated with AE-SN-induced caspase-3 cleavage in SKOV-3 cells. In conclusion, the AE-SN exhibited tumor suppression efficacy and improved the tumor suppression efficiency of cisplatin, doxorubicin, and docetaxel in human ovarian cancer cells. Therefore, the AE-SN is a candidate antitumor ingredient that can be used in developing future integrated chemotherapy for managing ovarian cancer.

Preclinical evaluation on the tumor suppression efficiency and combination drug effects of fermented wheat germ extract in human ovarian carcinoma cells

Fermented wheat germ extract (FWGE) is a nutrient supplement and a potential antitumor ingredient for developing an integrated chemotherapy with standard chemotherapeutic drugs for treating ovarian cancer patients. In this study, we evaluated the tumor suppression efficiency of FWGE in human ovarian carcinoma cells, SKOV-3 and ES-2, and found the half-maximal inhibitory concentrations (IC50s) to be 643.76 μg/mL and 246.11 μg/mL after 48 h of FWGE treatment. FWGE treatment also induced programmed cell death by activating the caspase-7 cleavage in both SKOV-3 and ES-2 cells, but only caspase-3 and poly(adenosine diphosphate-ribose) polymerase cleavages were activated in SKOV-3 cells. Moreover, FWGE exhibited combination drug effects with cisplatin and docetaxel in SKOV-3 and ES-2 cells by enhancing the cytotoxicity of both drugs. In conclusion, we found that FWGE not only suppressed cell growth but also induced caspase-3-related and caspase-7-related cell death in human ovarian carcinoma cells. FWGE treatment further enhanced the cytotoxicity of cisplatin and docetaxel, suggesting that FWGE is a potential ingredient in the development of adjuvant chemotherapy with cisplatin or docetaxel for treating ovarian cancer patients.

EBAG9 modulates host immune defense against tumor formation and metastasis by regulating cytotoxic activity of T lymphocytes

Estrogen receptor-binding fragment-associated antigen 9 (EBAG9) is a primary estrogen-responsive gene that we previously identified in MCF-7 breast cancer cells using the CpG genomic binding-site cloning technique. The expression of EBAG9 protein is often upregulated in malignant tumors, suggesting that this protein is involved in cancer pathophysiology. In the present study, we investigated the role of EBAG9 in host defense against implanted tumors in Ebag9-knockout (Ebag9KO) mice. MB-49 mouse bladder cancer cells were subcutaneously implanted into Ebag9KO and control mice. We found that tumor formation and metastasis to the lung by MB-49 cells were substantially reduced in Ebag9KO mice compared with control mice. The infiltration of CD8⁺, CD3⁺ and CD4⁺ T cells into the generated tumors was enhanced in Ebag9KO mice compared with controls. Notably, CD8⁺ T cells isolated from tumors in Ebag9KO mice exhibited substantial upregulation of immunity- and chemoattraction-related genes, including interleukin-10 receptor, interferon gamma, granzyme A, granzyme B and chemokine (C-X-C motif) receptor 3 compared with CD8⁺ T cells from tumors in control mice. The CD8⁺ T cells isolated from tumors in Ebag9KO mice also exhibited enhanced degranulation and increased cytolytic activity. Furthermore, the adoptive transfer of CD8⁺ T cells isolated from tumors in Ebag9KO host could repress tumor growth by MB-49 cells implanted in wild-type host. These results suggest that EBAG9 modulates tumor growth and metastasis by negatively regulating the adaptive immune response in host defense. EBAG9 could be a potential target for tumor immunotherapy.

[The involvement of RCAS1 in creating a suppressive tumor microenvironment in patients with pharyngeal squamous cell carcinoma]

INTRODUCTION

Tumor microenvironment makes up the stroma of the neoplasm and is the tissue that determines the growth and progression of the tumor and its ability to create metastases. THE AIM OF THE PRESENT STUDY: has been to evaluate the potential role of RCAS1 protein in creating the suppressive tumor microenvironment in pharyngeal squamous cell carcinomas. The immunoreactivity of RCAS1, CD3, CD25, CD68, CD69 and Foxp3 was assessed in the tissue samples of the tumor, in tumor microenvironment and in the reference samples of palatine tonsils in chronic inflammation.

RESULTS

A statistically significantly higher RCAS1 antigen immunoreactivity was identified in pharyngeal cancer samples than in the stromal samples, the presence of RCAS1 positive macrophages infiltrating the tumor and its stroma was also noticed. The statistically significantly higher RCAS1 antigen immunoreactivity level was identified in the pharyngeal cancer samples in patients with the presence of lymph node metastases in comparison to patients without metastases. The infiltration of CD68 positive cells (macrophages) was significantly higher in the stromal tissue samples than in cancer samples and it was in both, the tumor and the stroma, significantly higher in patients with the presence of lymph node metastases than in patients without metastases. Additionally the presence of CD3 positive TILs was noticed in the tissue of the tumor and in its stroma, the cells were activated, typified by CD69 immunoreactivity which was higher than in the reference samples, and impaired cytotoxicity with low CD25 antigen immunoreactivity. This observation confirmed the presence of selective immune suppression within the tumor and the stroma.

CONCLUSION

RCAS1, an active factor secreted by the tumor and present in its stroma may play an important role in the phenomenon of tumor escape from host immunological surveillance and in creating the immune tolerance for the tumor cells, as well as in the tumor microenvironment remodeling with creating its suppressive profile enabling the further tumor growth and metastases.

Association of positive EBAG9 immunoreactivity with unfavorable prognosis in breast cancer patients treated with tamoxifen

INTRODUCTION

Breast cancer is primarily a hormone-dependent tumor that is regulated by the status of the estrogen and progesterone receptors. We previously identified EBAG9 as an estrogen-responsive gene in MCF-7 human breast carcinoma cells. Upregulation of EBAG9 expression has been observed in several malignant tumors such as advanced breast cancers, indicating that EBAG9 might contribute to tumor progression.

PATIENTS AND METHODS

In the present study, we generated a monoclonal antibody against EBAG9, and then performed immunohistochemical analysis of EBAG9 expression in specimens obtained from breast cancer patients treated with tamoxifen as an adjuvant therapy.

RESULTS

EBAG9 immunoreactivity was detected in the cytoplasm of breast cancer cells and was significantly elevated in breast cancer samples from patients who relapsed during or after adjuvant tamoxifen treatment. Positive EBAG9 immunoreactivity was significantly correlated with poor patient prognosis.

CONCLUSION

These results suggest that EBAG9 expression in tumor regions is associated with an unfavorable prognosis in breast cancer patients treated with tamoxifen.

The membrane molecule RCAS1 induces immune cell apoptosis via the RCAS1-RCAS1R pathway

Tumor-associated antigen receptor-binding cancer antigen expressed on SiSo cells (RCAS1) has been identified as an estrogen-responsive gene and reportedly acts as a ligand for a putative receptor present in a variety of human cell lines and peripheral lymphocytes, thus leading them to apoptosis. In this study, we investigated the biological function of RCAS1 in vitro in inducing the apoptosis of immune cells. We detected the expression of the RCAS1 receptor (RCAS1R) in the cell lines, and investigated the mechanisms behind the apoptosis induced by RCAS1. HeLa cells were transfected with recombinant adenovirus Ad-RCAS1. RCAS1 induced the apoptosis of activated T cells, K562 cells and phytohemagglutinin (PHA)-activated Jurkat cells via the RCAS1-RCAS1R pathway. The expression of RCAS1R was induced. The intracellular overexpression of RCAS1 inhibited the growth of Jurkat and K562 cells. The expression of RCAS1 negatively correlated with the expression of glycogen synthase kinase 3β (GSK3β), but positively correlated with the expression of phosphorylated GSK3β (phGSK3β). RCAS1 expression was identified as a brown staining pattern in the breast cancer specimens. These findings may provide insight into the mechanisms through which tumor cells escape from immune surveillance.

The analysis of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) immunoreactivity within the microenvironment of the ovarian cancer lesion relative to the applied therapeutic strategy

RCAS1 is involved in generating the suppressive profile of the tumor microenvironment that helps cancer cells evade immune surveillance. The status of the cells surrounding the cancer nest may affect both the progression of the cancer and the development of metastases. In cases of ovarian cancer, a large number of patients do not respond to the applied therapy. The patient’s response to the applied therapy is directly linked to the status of the tumor microenvironment and the intensity of its suppressive profile. We analyzed the immunoreactivity of RCAS1 on the cells present in the ovarian cancer microenvironment in patients with the disease; these cells included macrophages and carcinoma-associated fibroblasts. Later we analyzed the immunoreactivity levels within these cells, taking into consideration the clinical stage of the cancer and the therapeutic strategy applied, such as the number of chemotherapy regiments, primary cytoreductive surgery, or the presence of advanced ascites. In the patients who did not respond to the therapy we observed significantly higher immunoreactivity levels of RCAS1 within the cancer nest than in those patients who did respond; moreover, in the non-responsive patients we found RCAS1 within both macrophages and carcinoma-associated fibroblasts. RCAS1 staining may provide information about the intensity of the immuno-suppressive microenvironment profile found in cases of ovarian cancer and its intensity may directly relate to the clinical outcome of the disease.

Maternal blood serum and plasma human tumor-associated antigen RCAS1 during the course of uncomplicated pregnancies: a prospective study

PROBLEM

we aimed to investigate the expression of the tumor-associated RCAS1 protein in maternal blood of uncomplicated pregnancies.

METHOD OF STUDY

maternal blood was obtained from women with uncomplicated pregnancies (N = 43) at 11-13, 20-22, 32-34, 37-38 weeks of gestation, and immediately after delivery. Serum RCAS1 concentration was studied by ELISA, and plasma mRNA was subjected to real-time (RT)-PCR.

RESULTS

serum RCAS1 protein concentration was significantly up-regulated at 11-13 and 20-22 weeks than that at 32-34 weeks and after delivery. RCAS1 mRNA level was significantly increased at 11-13 weeks than that at 37-38 weeks. A significant positive correlation was defined between RCAS1 serum concentration at 11-13 weeks and gestational age at delivery and that between plasma RCAS1 mRNA levels at 37-38 weeks and umbilical cord blood base excess. A significant negative correlation was found between RCAS1 serum concentration at 37-38 weeks and umbilical cord blood pH at delivery.

CONCLUSIONS

RCAS1 protein might have importance in the development of uncomplicated pregnancies and for the prediction of pregnancy outcome.

Akt3 controls vascular endothelial growth factor secretion and angiogenesis in ovarian cancer cells

The PI3 kinase/Akt pathway is commonly deregulated in human cancers, functioning in such processes as proliferation, glucose metabolism, survival and motility. We have previously described a novel function for one of the Akt isoforms (Akt3) in primary endothelial cells: the control of VEGF-induced mitochondrial biogenesis. We sought to determine if Akt3 played a similar role in carcinoma cells. Because the PI3 kinase/Akt pathway has been strongly implicated as a key regulator in ovarian carcinoma, we tested the role of Akt3 in this tumor type. Silencing of Akt3 by shRNA did not cause an overt reduction in mitochondrial gene expression in a series of PTEN positive ovarian cancer cells. Rather, we find that blockade of Akt3, results in smaller, less vascularized tumors in a xenograft mouse model that is correlated with a reduction in VEGF expression. We find that blockade of Akt3, but not Akt1, results in a reduction in VEGF secretion and retention of VEGF protein in the endoplasmic reticulum (ER). The reduction in secretion under conditions of Akt3 blockade is, at least in part, due to the down regulation of the resident golgi protein and reported tumor cell marker, RCAS1. Conversely, over-expression of Akt3 results in an increase in RCAS1 expression and in VEGF secretion. Silencing of RCAS1 using siRNA inhibits VEGF secretion. These findings suggest an important role for Akt3 in the regulation of RCAS1 and VEGF secretion in ovarian cancer cells.

Role of EBAG9 protein in coat protein complex I-dependent glycoprotein maturation and secretion processes in tumor cells

Many proteins mature within the secretory pathway by the acquisition of glycans. Failure to maintain the proper distribution of the glycosylation machinery might lead to disease. High expression levels of the ubiquitous Golgi protein estrogen receptor-binding fragment-associated gene 9 (EBAG9) in human tumors correlate with poor clinical prognosis, and EBAG9 overexpression in epithelial cell lines induces truncated glycans, typical of many carcinomas. Here, we addressed the pathogenetic link between EBAG9 expression and the alteration of the cellular glycome. We applied confocal microscopy, live imaging, pulse-chase labeling in conjunction with immunoprecipitation, and enzymatic activity assays in a variety of EBAG9-overexpressing or depleted epithelial tumor cell lines. EBAG9 shuttles between the ER-Golgi intermediate compartment and the cis-Golgi, and we demonstrate association of EBAG9 with coat protein complex I (COPI)-coated transport vesicles. EBAG9 overexpression imposes delay of endoplasmic reticulum-to-Golgi transport and mislocalizes components of the ER quality control and glycosylation machinery. Conversely, EBAG9 down-regulation accelerates glycoprotein transport through the Golgi and enhances mannosidase activity. Thus, EBAG9 acts as a negative regulator of a COPI-dependent ER-to-Golgi transport pathway in epithelial cells and represents a novel pathogenetic principle in which interference with intracellular membrane trafficking results in the emergence of a tumor-associated glycome.

Epigenetics in human melanoma

BACKGROUND

Recent technological advances have allowed us to examine the human genome in greater detail than ever before. This has opened the door to an improved understanding of the gene expression patterns involved with cancer.

METHODS

A review of the literature was performed to determine the role of epigenetic modifications in human melanoma. We focused the search on histone deacetylation, methylation of gene promoter regions, demethylation of CpG islands, and the role of microRNA. We examined the relationship between human melanoma epigenetics and their importance in tumorigenesis, tumor progression, and inhibition of metastasis. The development and clinical application of select pharmacologic agents are also discussed.

RESULTS

We identified several articles that have extensively studied the role of epigenetics in melanoma, further elucidating the complex processes involved in gene regulation and expression. Several new agents directly affect epigenetic mechanisms in melanoma, with divergent affects on the metastatic potential of melanoma.

CONCLUSIONS

Epigenetic mechanisms have emerged as having a central role in gene regulation of human melanoma, including the identification of several putative tumor suppressor genes and oncogenes. Further research will focus on the development of novel therapeutics that will likely target and alter such epigenetic changes.

EBAG9 inducing hyporesponsiveness of T cells promotes tumor growth and metastasis in 4T1 murine mammary carcinoma

The estrogen receptor-binding fragment-associated gene 9 (EBAG9) has been identified as an estrogen-responsive gene and was recently identified as a tumor-promoting and prognostic factor for renal cell carcinoma. We investigated whether EBAG9 expression was correlated with primary tumor growth and distant tumor metastasis in a murine breast carcinoma model. Knockdown expression of EBAG9 by small interfering RNA significantly suppressed tumor growth and metastasis in vivo in a highly malignant, spontaneously metastasizing 4T1 mouse mammary carcinoma model. 4T1 cells stably overexpressing EBAG9 developed larger and faster tumor growth and lung metastasis compared with parental 4T1 or 4T1 expressing vector alone. Strong specific cytotoxic T lymphocyte activity and enhanced gamma-interferon and interleukin-2 productions were induced in mice that received EBAG9 small interfering RNA therapy. Gene silencing of EBAG9 prolonged the survival of tumor-bearing mice and induced more intensive infiltration of CD8+ T cells in tumor mass. EBAG9 induced apoptosis of T cells, enhanced glycogen synthase kinase 3beta phosphorylation and inhibited gamma-interferon production of T cells when T lymphocytes were cocultured with 4T1 cells overexpressing EBAG9. Furthermore, overexpression of EBAG9 in 4T1 cells was accompanied with enhanced expression of chemokine (C-X-C motif) receptor 4, which might be involved in tumor metastasis. Taken together, our results suggested that EBAG9 promoted primary 4T1 mammary carcinoma growth and distant metastasis, and EBAG9 small interfering RNA exerted overt regression of tumor growth and metastasis. These findings might provide insights into the mechanism through which tumors evade immunosurveillance and provide a strategy for therapeutic intervention of cancer metastases.

Estrogen receptor-binding fragment-associated gene 9 expression and its clinical significance in human testicular cancer

OBJECTIVES

We previously demonstrated that estrogen receptor-binding fragment-associated gene 9 (EBAG9) is a tumor promoting factor in renal cell carcinoma (Ogushi T, Cancer Res. 2005; 65: 3700). Here, we evaluated EBAG9 expression and its clinical significance in normal and malignant human testicular tissues.

METHODS

We investigated the expression of EBAG9 in 90 testicular specimens (28 benign testicular tissue and 62 testicular germ cell tumor samples) by immunohistochemistry using rabbit polyclonal anti-EBAG9 antibody.

RESULTS

Positive immunostaining of EBAG9 in the cytoplasm was found in 32 (52%) cancerous lesions, whereas the immunoreactivity of EBAG9 was weak in benign testicular tissues. Serum lactate dehydrogenaze (LDH) level was significantly higher in EBAG9-positive cases (715.0 +/- 727.3) compared with the negative cases (221.4 +/- 126.8) (P = 0.0016). The EBAG9-positive cases among the patients with advanced clinical stage (Stage II and III) more frequently belonged to the intermediate or poor risk group in the International Germ Cell Consensus Prognostic Classification System (IGCCPCS), compared with the EBAG9-negative cases (P = 0.0012).

CONCLUSIONS

These findings suggest that increased expression of EBAG9 may play a significant role in cancer progression and aggressiveness in testicular germ cell tumors.

The human tumor-associated antigen RCAS1 in pregnancies complicated by pre-eclampsia

The human tumor-associated antigen RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is considered to play a role in the escape of tumor cells from immune surveillance and, at the same time, participates in the inhibition of the maternal immune response during pregnancy. The aim of our study was to investigate the expression of tumor-associated RCAS1 protein in the placenta and amniotic membranes and to assess and compare its concentration in amniotic fluid, maternal and cord blood sera in pregnancies complicated by pre-eclampsia. Samples were obtained from women with pre-eclampsia (N=9), pre-eclampsia with IUGR (N=4), normotensive IUGR (N=7) and healthy term controls (N=25) after delivery. Placentas were studied by immunohistochemistry, Western blot analysis and real-time (RT)-PCR. For assessment of RCAS1 protein concentrations in biological fluids, ELISA was performed. RCAS1 mRNA expression in the placentas of pre-eclamptic patients was significantly lower than in controls (p<0.01). The maternal blood serum RCAS1 protein concentration in the pre-eclampsia cases was also significantly lower than in controls (p=0.0207). The other study groups did not differ significantly. This study reveals the possible role of the RCAS1 protein in the development of pre-eclampsia through an immunological pathway.

Expression of receptor-binding cancer antigen expressed on SiSo cells and estrogen receptor subtypes in the normal, hyperplastic, and carcinomatous endometrium

The objectives were to study the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) and estrogen receptor (ER) subtypes in the normal, hyperplastic, and carcinomatous endometrium and to explore their possible role in carcinogenesis and progression of endometrial carcinoma. Immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to detect protein and messenger RNA expression of RCAS1, ER-alpha, and ER-beta in normal, hyperplastic, and carcinomatous endometrium. Western blotting was also used to detect the RCAS1 protein expression. Immunohistochemistry showed that the high expressions of RCAS1 protein were 0% (0/20), 9.1% (2/22), 40% (8/20), and 68.0% (34/50) in normal, simple, and complex hyperplasia, atypical hyperplasia, and endometrial carcinoma, respectively. There was a significant difference between each group (P < 0.05). The high-level expression of RCAS1 was detected more frequently in endometrial cancer with deep myometrial invasion, vascular invasion, and positive ER-alpha (P < 0.05). Two staining patterns of RCAS1 were observed. All normal, simple, and complex hyperplastic endometrium showed P pattern, while all malignant endometrium were of the D pattern. In atypical endometrium, 25% (5/20) cases showed D pattern. The Western blotting and RT-PCR results correlated with the immunohistochemistry results. The expression and distribution of RCAS1 may be involved in the malignant transformation of endometrium, and RCAS1 coexpression with ER-alpha may be associated with development and metastasis of endometrial carcinoma.

Epitomics: serum screening for the early detection of cancer on microarrays using complex panels of tumor antigens

Efforts toward the development of early detection assays for cancers have traditionally depended on single biomarker molecules. Current technologies have been disappointing and have not resulted in diagnostic tests suitable for clinical practice. Using a high-throughput cloning method, a panel of epitopes/antigens that react with autoantibodies to tumor proteins in the serum of patients with ovarian cancer have been isolated. Discovery of biomarker panels was directed in an unbiased fashion by cloning a large panel of epitopes or tumor antigens, rather than individual biomarkers without a previous notion of their function. The binding properties of these serum antitumor antibodies on microarrays and advanced bioinformatics tools led to a panel of diagnostic antigens. The sequences that were identified using this new technology will lead to the discovery of novel disease-related proteins that have diagnostic value for the presymptomatic detection of cancer. It has been demonstrated that this approach can detect these autoantibodies in the sera of Stage I ovarian cancer patients. There are numerous advantages of employing serum antibodies as the analytes, not the least of which is the ability to rapidly adapt these assays to standard clinical platforms. This technology of global epitope/antigen profiling is referred to as 'epitomics'.

Steroid receptor coactivator-3, a homolog of Taiman that controls cell migration in the Drosophila ovary, regulates migration of human ovarian cancer cells

Border cell migration is a process that occurs during Drosophila ovarian development in which cells derived from a simple epithelium migrate and invade neighboring tissue. This process resembles the behavior of cancerous cells that derive from the simple epithelium of the human ovary. One important regulator of border cell migration is Taiman, a homolog of steroid receptor coactivator-3 (SRC-3). Because increasing evidence indicates that similarities exist between the molecular control of migration of border cells and of cancer cells, we investigated whether SRC-3 controls ovarian cancer cell migration. Little or no SRC-3 expression was detected in normal ovarian surface epithelium, ovarian cysts and borderline ovarian tumors that lack stromal invasion. In contrast, SRC-3 was abundantly expressed in high-grade ovarian carcinomas. Inhibiting SRC-3 expression in ovarian cancer cells markedly reduced cell spreading and migration, and altered intracellular localization of focal adhesion kinase. This inhibitory effect on cell migration was independent of the estrogen receptor (ER) status of the cells. These studies reveal a novel role for SRC-3 in ovarian cancer progression by promoting cell migration, independently of its role in estrogen receptor signaling.

Expression of estrogen-responsive finger protein (Efp) is associated with advanced disease in human epithelial ovarian cancer

OBJECTIVE

The estrogen-responsive ring finger protein (Efp) gene, one of estrogen receptor (ER) target genes, is considered to be essential for estrogen-dependent cell proliferation. To understand the estrogenic action on ovarian cancer, we studied the relationships between Efp and ERs expressions and the correlations of Efp expression with clinicopathological parameters in epithelial ovarian cancer.

METHODS

The protein expressions for Efp, ERalpha and ERbeta were examined by immunoblotting in 12 ovarian cancer cell lines. Efp mRNA expressions were evaluated by quantitative RT-PCR in 12 ovarian cancer cell lines. A total of 100 surgical specimens diagnosed as epithelial ovarian cancer were examined immunohistochemically using antibodies for Efp, ERalpha and ERbeta.

RESULTS

Efp protein was detected in 8 out of 12 cell lines. In Efp protein-positive cell lines, Efp mRNA was expressed higher than that in negative (P=0.021). All of the Efp protein-positive cell lines simultaneously expressed either ERalpha or ERbeta protein. By immunohistochemical staining, Efp immunoreactivity was detected in 63 out of 100 ovarian cancer specimens and positive signals were in the cytoplasm of carcinoma cells. There were significant correlations between Efp and ERalpha, ERbeta immunoreactivity (Efp and ERalpha, P=0.022; Efp and ERbeta, P=0.032). Efp expression was significantly higher in a subgroup with serous adenocarcinoma (P=0.010) and with advanced disease (P=0.026). No significant relationship was detected between Efp immunoreactivity and overall survival.

CONCLUSION

The expression of Efp was detected in human epithelial ovarian cancer and high expression of Efp was correlated with advanced disease and serous adenocarcinoma, and ERs status.

Estrogen receptor-binding fragment-associated antigen 9 is a tumor-promoting and prognostic factor for renal cell carcinoma

The estrogen receptor-binding fragment-associated antigen 9 (EBAG9) has been identified as a primary estrogen-responsive gene in human breast cancer MCF7 cells. A high expression of EBAG9 has been observed in invasive breast cancer and advanced prostate cancer, suggesting a tumor-promoting role of the protein in malignancies. Here we show that intratumoral (i.t.) administration of small interfering RNA against EBAG9 exerted overt regression of tumors following s.c. implantation of murine renal cell carcinoma (RCC) Renca cells. Overexpression of EBAG9 did not promote the proliferation of culture Renca cells; however, the inoculated Renca cells harboring EBAG9 (Renca-EBAG9) in BALB/c mice grew faster and developed larger tumors compared with Renca cells expressing vector alone (Renca-vector). After renal subcapsular implantation, Renca-EBAG9 tumors significantly enlarged compared with Renca-vector tumors in BALB/c mice, whereas both Renca-EBAG9 and Renca-vector tumors were developed with similar volumes in BALB/c nude mice. No apparent difference was observed in specific cytotoxic T-cell responses against Renca-EBAG9 and Renca-vector cells; nonetheless, the number of infiltrating CD8+ T lymphocytes was decreased in Renca-EBAG9 subcapsular tumors. Furthermore, immunohistochemical study of EBAG9 in 78 human RCC specimens showed that intense and diffuse cytoplasmic immunostaining was observed in 87% of the cases and positive EBAG9 immunoreactivity was closely correlated with poor prognosis of the patients. Multivariate analysis revealed that high EBAG9 expression was an independent prognostic predictor for disease-specific survival (P = 0.0485). Our results suggest that EBAG9 is a crucial regulator of tumor progression and a potential prognostic marker for RCC.

Reevaluation of the 22-1-1 antibody and its putative antigen, EBAG9/RCAS1, as a tumor marker

Background

Tumor-associated antigens are appreciated as diagnostic markers, but they have also prompted tremendous efforts to develop tumor-specific immunotherapy. A previously cloned tumor-associated antigen, EBAG9, was initially defined by reactivity with the monoclonal antibody 22-1-1. Functionally, the EBAG9-encoded gene-product was believed to induce apoptosis in activated immune cells. However, using a cell-biological approach we identified EBAG9 as a Golgi-resident modulator of O-linked glycan expression, the latter product was then recognized by the 22-1-1 antibody. Secondly, EBAG9 expression was found physiologically in all murine tissues examined. This raised the question if EBAG9 is tumor-specific and mediates apoptosis itself or through O-linked glycans generated, among them the cognate 22-1-1 antigen Tn.

Methods

We have used immunohistochemistry to detect the expression of 22-1-1 and EBAG9 in various tissues. Correlation between expression of both antigens in cell lines was analysed by immunoblot and flow cytometry. Apoptosis was studied by using flow cytometry and Caspase-Glo™ 3/7 assay kit. Cellular distribution of EBAG9 was analysed by electron and confocal microscopy.

Results

Here, we compared expression of the 22-1-1 and EBAG9-defined antigens in normal and neoplastic tissues in situ. In contrast to 22-1-1 staining, EBAG9 is a ubiquitously expressed antigen in all normal and cancerous tissues. Functional studies on the role of 22-1-1 reactive material did not support any evidence for apoptosis induction. Employing electron and confocal microscopy, a refined subcellular localization of EBAG9 at the Golgi was obtained.

Conclusion

We suggest that the estrogen-inducible EBAG9 gene-product and the 22-1-1 defined antigen are structurally and functionally separate antigens.

EBAG9 adds a new layer of control on large dense-core vesicle exocytosis via interaction with Snapin

Regulated exocytosis is subject to several modulatory steps that include phosphorylation events and transient protein-protein interactions. The estrogen receptor-binding fragment-associated gene9 (EBAG9) gene product was recently identified as a modulator of tumor-associated O-linked glycan expression in nonneuronal cells; however, this molecule is expressed physiologically in essentially all mammalian tissues. Particular interest has developed toward this molecule because in some human tumor entities high expression levels correlated with clinical prognosis. To gain insight into the cellular function of EBAG9, we scored for interaction partners by using the yeast two-hybrid system. Here, we demonstrate that EBAG9 interacts with Snapin, which is likely to be a modulator of Synaptotagmin-associated regulated exocytosis. Strengthening of this interaction inhibited regulated secretion of neuropeptide Y from PC12 cells, whereas evoked neurotransmitter release from hippocampal neurons remained unaltered. Mechanistically, EBAG9 decreased phosphorylation of Snapin; subsequently, association of Snapin with synaptosome-associated protein of 25 kDa (SNAP25) and SNAP23 was diminished. We suggest that the occurrence of SNAP23, Snapin, and EBAG9 also in nonneuronal cells might extend the modulatory role of EBAG9 to a broad range of secretory cells. The conjunction between EBAG9 and Snapin adds an additional layer of control on exocytosis processes; in addition, mechanistic evidence is provided that inhibition of phosphorylation has a regulatory function in exocytosis.

Modulation of gene expression by tumor-derived p53 mutants

p53 mutants with a single amino acid substitution are overexpressed in a majority of human cancers containing a p53 mutation. Overexpression of the mutant protein suggests that there is a selection pressure on the cell indicative of an active functional role for mutant p53. Indeed, H1299 cells expressing mutant p53-R175H, p53-R273H or p53-D281G grow at a faster rate compared with a control cell line. Using p53-specific small interfering RNA, we show that the growth rate of mutant p53-expressing cells decreases as mutant p53 level decreases, demonstrating that the increased cellular growth is dependent on p53 expression. Increased growth rate is not observed for H1299 cell clones expressing mutant p53-D281G (L22Q/W23S), which has been shown to be defective in transactivation in transient transcriptional assays. This shows that the increased growth rate imparted by mutant p53 in H1299 cells requires the transactivation function of mutant p53. By performing microarray hybridization analyses, we show that constitutive expression of three common p53 mutants (p53-R175H, p53-R273H, and p53-D281G) in H1299 human lung carcinoma cells evokes regulation of a common set of genes, a significant number of which are involved in cell growth regulation. Predictably, H1299 cells expressing p53-D281G (L22Q/W23S) are defective in up-regulating a number of these genes. The differences in expression profiles induced by individual p53 mutants in the cells may be representative of the p53 mutants and how they can affect gene expression resulting in the observed "gain of function" phenotypes (i.e., increased growth rate, decreased sensitivity to chemotherapeutic agents, and so forth).