Characterization of ascites-derived ovarian tumor cells from spontaneously occurring ovarian tumors of the chicken: evidence for E-cadherin upregulation

Beyond the Lab: What We Can Learn about Cancer from Wild and Domestic Animals

Cancer research has benefited immensely from the use of animal models. Several genetic tools accessible in rodent models have provided valuable insight into cellular and molecular mechanisms linked to cancer development or metastasis and various lines are available. However, at the same time, it is important to accompany these findings with those from alternative or non-model animals to offer new perspectives into the understanding of tumor development, prevention, and treatment. In this review, we first discuss animals characterized by little or no tumor development. Cancer incidence in small animals, such as the naked mole rat, blind mole rat and bats have been reported as almost negligible and tumor development may be inhibited by increased defense and repair mechanisms, altered cell cycle signaling and reduced rates of cell migration to avoid tumor microenvironments. On the other end of the size spectrum, large animals such as elephants and whales also appear to have low overall cancer rates, possibly due to gene replicates that are involved in apoptosis and therefore can inhibit uncontrolled cell cycle progression. While it is important to determine the mechanisms that lead to cancer protection in these animals, we can also take advantage of other animals that are highly susceptible to cancer, especially those which develop tumors similar to humans, such as carnivores or poultry. The use of such animals does not require the transplantation of malignant cancer cells or use of oncogenic substances as they spontaneously develop tumors of similar presentation and pathophysiology to those found in humans. For example, some tumor suppressor genes are highly conserved between humans and domestic species, and various tumors develop in similar ways or because of a common environment. These animals are therefore of great interest for broadening perspectives and techniques and for gathering information on the tumor mechanisms of certain types of cancer. Here we present a detailed review of alternative and/or non-model vertebrates, that can be used at different levels of cancer research to open new perspectives and fields of action.

Metformin Affects the Transcriptomic Profile of Chicken Ovarian Cancer Cells

Ovarian cancer is the most lethal gynecological malignancy in women. Metformin intake is associated with a reduced incidence of ovarian cancer and increased overall survival rate. We determined the effect of metformin on sphere formation, extracellular matrix invasion, and transcriptome profile of ovarian cancer cells (COVCAR) isolated from ascites of chickens that naturally developed ovarian cancer. We found that metformin treatment significantly decreased sphere formation and invasiveness of COVCAR cells. RNA-Seq data analysis revealed 0, 4, 365 differentially expressed genes in cells treated with 0.5, 1, 2 mM metformin, respectively compared to controls. Transcriptomic and ingenuity pathway analysis (IPA) revealed significant downregulation of MMP7, AICDA, GDPD2, APOC3, APOA1 and predicted inhibition of upstream regulators NFKB, STAT3, TP53 that are involved in epithelial-mesenchymal transition, DNA repair, and lipid metabolism. The analysis revealed significant upregulation of RASD2, IHH, CRABP-1 and predicted activation of upstream regulators VEGF and E2F1 that are associated with angiogenesis and cell cycle. Causal network analysis revealed novel pathways suggesting predicted inhibition of ovarian cancer through master regulator ASCL1 and dataset genes DCX, SEMA6B, HEY2, and KCNIP2. In summary, advanced pathway analysis in IPA revealed novel target genes, upstream regulators, and pathways affected by metformin treatment of COVCAR cells.

From crypts to enteroids: establishment and characterization of avian intestinal organoids

Intestinal organoids (IO), known as “mini-guts”, derived from intestinal crypts, are self-organizing three-dimensional (3D) multicellular ex vivo models that recapitulate intestine epithelial structure and function and have been widely used for studying intestinal physiology, pathophysiology, molecular mechanisms of host-pathogen interactions, and intestinal disease in mammals. However, studies on avian IO are limited and the development of long-term cultures of IO model for poultry research is lacking. Therefore, the objectives of this study were to generate crypt-derived organoids from chicken intestines and to optimize conditions for cell growth and enrichments, passages, and cryopreservation. Crypts were collected from the small intestines of birds at embryonic d-19 and ceca from layer and broiler chickens with ages ranging from d 1 to 20 wk, embedded in a basement membrane matrix, and cultured with organoid growth media (OGM) prepared in house. The crypt-derived organoids were successfully grown and propagated to form 3D spheres like structures that were cultured for up to 3 wk. Organoids were formed on d one, budding appeared on d 3, and robust budding was observed on d 7 and beyond. For cryopreservation, dissociated organoids were resuspended in a freezing medium. The characteristics of IO upon extended passages and freeze-thaw cycles were analyzed using reverse transcription (RT)-PCR, immunoblotting, and live cell imaging. Immunoblotting and RT-PCR using E-cadherin (the marker for epithelial cells), leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5, the marker for stem cells), chromogranin A (the marker for enteroendocrine cells), lysozyme (the marker for Paneth cells), and mucin (the biomarker for goblet cells) confirmed that IO were composed of heterogeneous cell populations, including epithelial cells, stem cells, enteroendocrine cells, Paneth cells, and goblet cells. Furthermore, OGM supplemented with both valproic acid and CHIR99021, a glycogen synthase kinase 3β inhibitor and a histone deacetylase inhibitor, increased the size of the avian IO (P < 0.001). To the best of our knowledge, this is the first comprehensive report for establishing long-term, organoid culture models from small intestines and ceca of layer and broiler chickens. This model will facilitate elucidation of the mechanisms impacting host-pathogen interactions, eventually leading to the discovery of pathogen intervention strategies in poultry.

A Review of Principal Studies on the Development and Treatment of Epithelial Ovarian Cancer in the Laying Hen Gallus gallus

Often referred to as the silent killer, ovarian cancer is the most lethal gynecologic malignancy. This disease rarely shows any physical symptoms until late stages and no known biomarkers are available for early detection. Because ovarian cancer is rarely detected early, the physiology behind the initiation, progression, treatment, and prevention of this disease remains largely unclear. Over the past 2 decades, the laying hen has emerged as a model that naturally develops epithelial ovarian cancer that is both pathologically and histologically similar to that of the human form of the disease. Different molecular signatures found in human ovarian cancer have also been identified in chicken ovarian cancer including increased CA125 and elevated E-cadherin expression, among others. Chemoprevention studies conducted in this model have shown that decreased ovulation and inflammation are associated with decreased incidence of ovarian cancer development. The purpose of this article is to review the major studies performed in laying hen model of ovarian cancer and discuss how these studies shape our current understanding of the pathophysiology, prevention, and treatment of epithelial ovarian cancer.

Effects of age, weight, and housing system on prevalence of dead on arrival and carcass condemnation causes in laying hens

Causes of condemnation and dead on arrival (DoA) birds were studied at the slaughterhouse and effects of age, BW, and housing system were investigated. A total of 1,156 (0.18%) birds were found DoA and 20,754 carcasses out of 629,331 (3.30%) were condemned during postmortem inspection. The main reasons for condemnation were peritonitis, septicemia, salpingitis, emaciation, and tumors. The mean percentages of condemnation by septicemia and emaciation differed according to age and BW groups and were more common in batches of younger (≤87 wk) and lighter (≤1.88 kg) birds. Moreover, peritonitis and ascites differed significantly between age groups, occurring more frequently in batches of older hens. The presence of tumors of the reproductive system was more frequently observed in older and heavier hens. This result raises the possibility of tumors being correlated with the higher number of prior ovulatory events. The total condemnation rate was lower in hens from organic systems, followed by free-range, and differed significantly from barns and cage systems. Carcasses with ascites and peritonitis were found more commonly in hens from cages and barns and both differed significantly from organic systems. Salpingitis was statistically more prevalent in barns, presenting differences from organic and free-range systems. Monitoring condemnation causes of end-of-lay hens at slaughter provided a better understanding of health and welfare issues in different housing systems and allowed to identify potential welfare problems, which can be used to improve management and welfare on farms.

Characterization of ascites-derived aldehyde dehydrogenase-positive ovarian cancer stem cells isolated from Leghorn chickens

Leghorn chickens are used as a preclinical model of ovarian cancer as they develop epithelial ovarian adenocarcinoma spontaneously at a very high frequency. Ovarian cancer is the most lethal disease among all gynecological malignancies in women. A small proportion of ovarian cancer stem cells are responsible for drug resistance and relapse of ovarian cancer. The objectives of this study are to isolate ovarian cancer stem cells from ascites of Leghorn chickens that spontaneously developed ovarian cancer and to determine their invasiveness, spheroid formation in three-dimensional culture devoid of extracellular matrix over several months. Ovarian cancer cells obtained from ascites were subjected to ALDEFLOUR assay that measures aldehyde dehydrogenase (ALDH) activity to separate ALDH1⁺ and ALDH1^- cells by fluorescence-activated cell sorting. The cells were cultured using serum-free media for up to 6 mo in ultra-low attachment plates. Invasiveness of ALDH1⁺ and ALDH1^- cells was determined by Matrigel invasion assay. Cellular uptake of acetylated low-density lipoprotein was evaluated. A small proportion (<4.75%) of ovarian cancer cells isolated from ascites were found to be ALDH1⁺ cells. ALDH1⁺ cells formed a greater number of spheroids and were also highly invasive in extracellular matrix compared to ALDH1^- cells. Several spheroids developed 0.1- to 1-mm-long capillary-like tubules connecting other spheroids, thus forming a complex network that underwent remodeling over several months. Cells in the spheroids incorporated acetylated low-density lipoprotein suggestive of scavenger receptor activity. In summary, ALDH1⁺ ovarian cancer stem cells isolated from ascites of chickens appear to be invasive and form spheroids with complex networks of tubules reminiscent of vascular mimicry. Understanding the structure and function of spheroids and tubular network would provide valuable insight into the biology of ovarian cancer and improve poultry health.

Retrospective study of small pet tumors treated with Artemisia annua and iron

Artemisinin from Artemisia annua L. and its derivatives are well-known antimalarial drugs. In addition, in vitro studies, in vivo studies and clinical trials have demonstrated that these drugs exhibit anticancer activity in human patients with cancer. Therefore, the aim of the present study was to investigate whether a phytotherapeutic A. annua preparation exerts anticancer activity in veterinary tumors of small pets. Dogs and cats with spontaneous cancer (n=20) were treated with standard therapy plus a commercial A. annua preparation (Luparte^®) and compared with a control group treated with standard therapy alone (n=11). Immunohistochemical analyses were performed with formalin-fixed paraffin-embedded tumor biopsies to analyze the expression of transferrin receptor (TfR) and the proliferation marker Ki-67 as possible biomarkers to assess treatment response of tumors to A. annua. Finally, the expression levels of TfR and Ki-67 were compared with the IC₅₀ values towards artemisinin in two dog tumor cells lines (DH82 and DGBM) and a panel of 54 human tumor cell lines. Retrospectively, the present study assessed the survival times of small animals treated by standard therapy with or without A. annua. A. annua treatment was associated with a significantly higher number of animals surviving >18 months compared with animals without A. annua treatment (P=0.0331). Using a second set of small pet tumors, a significant correlation was identified between TfR and Ki-67 expression by immunohistochemistry (P=0.025). To further assess the association of transferrin and Ki-67 expression with cellular response to artemisinin, the present study compared the expression of these two biomarkers and the IC₅₀ values for artemisinin in National Cancer Institute tumor cell lines in vitro. Both markers were inversely associated with artemisinin response (P<0.05), and the expression levels of TfR and Ki-67 were significantly correlated (P=0.008). In conclusion, the promising results of the present retrospective study warrant further confirmation by prospective studies in the future.

Differential Expression Pattern of Epithelial Mesenchymal Transition Gens: AXL, GAS6, Claudin-1, and Cofilin-1, in Different Stages of Epithelial Ovarian Cancer

BACKGROUND

Epithelial ovarian cancer (EOC), is the fatal form of gynecological cancer. Almost 70% of ovarian cancer patients are detected at an advanced stage (III-IV) with metastases. Epithelial-mesenchymal transition (EMT) is a critical process associated with metastasis. This study investigated the expression levels of AXL, GAS6, Claudin-1, and Cofilin-1, as genes involved in EMT in relation to clinicopathologic features in ovarian cancer patients.

METHODS

In this descriptive study, 78 ovarian epithelial cancer patients were enrolled. Samples were provided by the Iran National Tumor Bank, founded by the Cancer Institute of Tehran University of Medical Sciences in 2017. The expression levels of AXL, GAS6, Claudin-1, and Cofilin-1 genes were investigated in a fresh, frozen tumor sample and normal adjacent tissue by real-time PCR (RT-PCR).

RESULTS

Findings showed a significant relationship between the overexpression of AXL and TNM staging (P=0.03). The expression level of GAS6 decreased in more advanced stages (P=0.01). There is a negative relationship between Cofilin-1 expression level and TNM staging (P=0.002). Claudin-1 expression level was higher in low stages compared with that in high stages (P=0.01). There was no relationship between gene expression levels of target genes with size and grade of the tumor.

CONCLUSION

Given the importance of these genes in EMT, alteration in their expression pattern can contribute to the progression of the disease and distant metastasis of cancer cells. Additionally, knowing the alteration pattern of these genes expression can help to better understanding and prediction of the prognosis of EOC.

Histology of the Ovary of the Laying Hen (Gallus domesticus)

The laying hen (Gallus domesticus) is a robust animal model for epithelial ovarian cancer. The use of animal models is critical in identifying early disease markers and developing and testing chemotherapies. We describe the microscopic characteristics of the normally functioning laying hen ovary and proximal oviduct to establish baselines from which lesions associated with ovarian cancer can be more readily identified. Ovaries and oviducts were collected from 18-month-old laying hens (n = 18) and fixed in 10% neutral buffered formalin. Hematoxylin- and eosin-stained sections were examined by light microscopy. Both post-ovulatory follicular regression and atresia of small follicles produce remnant clusters of vacuolated cells with no histological evidence that scar tissue persists. Infiltrates of heterophils are associated with atresia of small follicles, a relationship not previously documented in laying hen ovaries. Because these tissues can be mistaken for cancerous lesions, we present a detailed histological description of remnant Wolffian tissues in the laying hen ovary. Immunohistochemical staining for pancytokeratin produced a positive response in ovarian surface epithelium and staining for vimentin produced a positive response in granulosa cells of follicles. Epithelial cells lining glands of the remnant epoöphoron had a positive response to both pancytokeratin and vimentin, a result also observed in women.

Chemopreventive and Antitumor Efficacy of Curcumin in a Spontaneously Developing Hen Ovarian Cancer Model

We investigated the effect of daily dietary curcumin intake on the development and progression of spontaneous ovarian cancer in a galline (hen) model, as the chicken is the only nonhuman animal in which ovarian cancer spontaneously develops with a high prevalence. At the end of 12 months, ovarian cancer had spontaneously developed in 39% (35/90) of control hens not fed curcumin (n = 90). In comparison, it spontaneously developed in 27% (24/90) and 17% (15/90) of hens given curcumin at 25.8 (n = 90) and 53.0 mg/day (n = 90), respectively (P = 0.004). This represented significant dose-dependent reductions in overall ovarian cancer incidence in the 25.8 and 53.0 mg/day curcumin-fed groups (31% and 57%, respectively). Daily curcumin intake also reduced ovarian tumor sizes (P = 0.04) and number of tumors (P = 0.006). Evaluation of the molecular mechanisms underlying the chemopreventive and antitumor effects of curcumin revealed that NF-κB and STAT3 signaling pathways were significantly inhibited but that the nuclear factor erythroid 2/heme oxygenase 1 antioxidant pathway was induced by curcumin intake in a dose-dependent manner in ovarian tissues (P < 0.05). Sequencing of the Ras family genes (KRAS, NRAS, and HRAS) revealed less frequent KRAS and HRAS mutations in ovarian tumors in the curcumin-fed animals. In conclusion, our results demonstrated for the first time that daily curcumin intake leads to a significant and dose-dependent reduction in spontaneous ovarian cancer incidence and tumor growth, indicating a tremendous role for curcumin as a chemopreventive strategy for ovarian cancer. Cancer Prev Res; 11(1); 59-67. ©2017 AACR.

The PeptideAtlas of the Domestic Laying Hen

Proteomics-based biological research is greatly expanded by high-quality mass spectrometry studies, which are themselves enabled by access to quality mass spectrometry resources, such as high-quality curated proteome data repositories. We present a PeptideAtlas for the domestic chicken, containing an extensive and robust collection of chicken tissue and plasma samples with substantial value for the chicken proteomics community for protein validation and design of downstream targeted proteome quantitation. The chicken PeptideAtlas contains 6646 canonical proteins at a protein FDR of 1.3%, derived from ∼100 000 peptides at a peptide level FDR of 0.1%. The rich collection of readily accessible data is easily mined for the purposes of data validation and experimental planning, particularly in the realm of developing proteome quantitation workflows. Herein we demonstrate the use of the atlas to mine information on common chicken acute-phase proteins and biomarkers for cancer detection research, as well as their localization and polymorphisms. This wealth of information will support future proteome-based research using this highly important agricultural organism in pursuit of both chicken and human health outcomes.

Expression of adiponectin and its receptors is altered in epithelial ovarian tumors and ascites-derived ovarian cancer cell lines

OBJECTIVES

Recent evidence suggests that higher body mass index is associated with a modest increase in ovarian cancer risk. Reduced serum levels of adiponectin are correlated with obesity and increased cancer risk. The objectives of the present study are to determine if expressions of adiponectin and its receptors, AdipoR1 and AdipoR2, are altered in epithelial ovarian tumors and ascites-derived ovarian cancer cell lines and to determine if plasma adiponectin levels are altered in the chicken model of ovarian cancer.

METHODS

Adiponectin, AdipoR1, and AdipoR2 mRNA concentrations in ovaries and chicken ovarian cancer (COVCAR) cell lines were determined by quantitative real-time polymerase chain reaction analysis. Existence of adiponectin isoforms in the ovaries and COVCAR cells was identified by nondenaturing gel electrophoresis. Adiponectin, AdipoR1, and AdipoR2 protein amounts were determined by Western blot analysis. Plasma total adiponectin levels were determined by an enzyme immunoassay.

RESULTS

Adiponectin, AdipoR1, and AdipoR2 mRNA concentrations were significantly lower in cancerous ovaries and COVCAR cell lines compared with normal ovaries and normal ovarian surface epithelial (NOSE) cells, respectively. Adiponectin in ovary and COVCAR cell lines appeared as a heavy-molecular-weight isoform that is greater than 720-kd mass. In addition, a lower-molecular-weight adiponectin isoform was found in COVCAR cells but not in NOSE cells. Adiponectin and AdipoR1 protein concentrations were not different in COVCAR cell lines compared with NOSE cells. However, AdipoR2 protein concentrations were significantly higher in cancerous ovaries but lower in COVCAR cell lines compared with normal ovaries and NOSE cells, respectively. Plasma adiponectin concentrations were not different in chickens that had ovarian carcinoma compared with control animals.

CONCLUSIONS

Expression of adiponectin in ovarian tumors and in metastatic ovarian tumor cells is likely to affect cellular metabolism and proliferation through activating AdipoR1 and/or AdipoR2. Plasma adiponectin levels may not be predictive of advanced stages of ovarian tumor in the chicken model.

The chicken model of spontaneous ovarian cancer

The chicken is a unique experimental model for studying the spontaneous onset and progression of ovarian cancer (OVC). The prevalence of OVC in chickens can range from 5 to 35% depending on age, genetic strain, reproductive history, and diet. Furthermore, the chicken presents epidemiological, morphological, and molecular traits that are similar to human OVC making it a relevant experimental model for translation research. Similarities to humans include associated increased risk of OVC with the number of ovulations, common histopathological subtypes including high-grade serous, and molecular-level markers or pathways such as CA-125 expression and p53 mutation frequency.  Collectively, the similarities between chicken and human OVC combined with a tightly controlled genetic background and predictable onset window provides an outstanding experimental model for studying the early events and progression of spontaneous OVC tumors under controlled environmental conditions. This review will cover the existing literature on OVC in the chicken and highlight potential opportunities for further exploitation (e.g. biomarkers, prevention, treatment, and genomics).

The promise and challenge of ovarian cancer models

The complexity and heterogeneity of ovarian cancer cases are difficult to reproduce in in vitro studies, which cannot adequately elucidate the molecular events involved in tumor initiation and disease metastasis. It has now become clear that, although the multiple histological subtypes of ovarian cancer are being treated with similar surgical and therapeutic approaches, they are in fact characterized by distinct phenotypes, cell of origin, and underlying key genetic and genomic alterations. Consequently, the development of more personalized treatment methodologies, which are aimed at improving patient care and prognosis, will greatly benefit from a better understanding of the key differences between various subtypes. To accomplish this, animal models of all histotypes need to be generated in order to provide accurate in vivo platforms for research and the testing of targeted treatments and immune therapies. Both genetically engineered mouse models (GEMMs) and xenograft models have the ability to further our understanding of key mechanisms facilitating tumorigenesis, and at the same time offer insight into enhanced imaging and treatment modalities. While genetic models may be better suited to examine oncogenic functions and interactions during tumorigenesis, patient-derived xenografts (PDXs) are likely a superior model to assess drug efficacy, especially in concurrent clinical trials, due to their similarity to the tumors from which they are derived. Genetic and avatar models possess great clinical utility and have both benefits and limitations. Additionally, the laying hen model, which spontaneously develops ovarian tumors, has inherent advantages for the study of epithelial ovarian cancer (EOC) and recent work champions this model especially when assessing chemoprevention strategies. While high-grade ovarian serous tumors are the most prevalent form of EOC, rarer ovarian cancer variants, such as small cell ovarian carcinoma of the hypercalcemic type and transitional cell carcinoma, or non-epithelial tumors, including germ cell tumors, will also benefit from the generation of improved models to advance our understanding of tumorigenic mechanisms and the development of selective therapeutic options.

Aquaporin 5 expression is altered in ovarian tumors and ascites-derived ovarian tumor cells in the chicken model of ovarian tumor

BACKGROUND

Aquaporin 5 (AQP5), a member of the aquaporin family of transmembrane channel proteins, is involved in water transport and cellular proliferation in various tumors. The objective of this study was to determine cellular localization of aquaporin 5 (AQP5) in the ovarian tumors of chicken, a preclinical model for human ovarian tumor and to determine if AQP5 mRNA and protein expression levels in cancerous chicken ovaries and in ascites-derived chicken ovarian cancer (COVCAR) cell lines are different from normal ovaries and normal ovarian surface epithelial (NOSE) cells, respectively.

METHODS

Immunohistochemical staining was performed to determine the localization of AQP5-immunoreactive (ir) cells in normal and cancerous ovaries. To determine AQP5 mRNA and protein concentrations in cancerous ovaries and COVCAR cell lines, quantitative real time PCR and Western blotting analysis were performed, respectively. Student's t-test was performed to compare the levels of AQP5 mRNA or protein in cancerous ovaries and COVCAR cell lines with that of normal ovaries and NOSE cells, respectively.

RESULTS

AQP5-ir cells were localized in granulosa and theca layers of normal ovarian follicles whereas cancerous ovaries showed AQP5 immunostaining in the surface epithelium, fibroblast cells of the stroma, and in the cells lining tumor cysts and acini. AQP5 mRNA concentration were significantly lesser while AQP5 protein concentrations were significantly greater in cancerous ovaries compared to that in normal ovaries (P < 0.05). Whereas AQP5 mRNA concentrations were significantly greater while AQP5 protein concentrations were lesser (P < 0.05) in COVCAR cell lines compared with that in NOSE cells.

CONCLUSION

AQP5 is differentially expressed in ovarian tumor and in COVCAR cell lines suggesting a potential involvement of AQP5 in ovarian tumorigenesis, metastasis, and survival of ovarian tumor cells in ascites.