Rodent models for ovarian cancer research

Incidence of malignant transformation in the oviductal fimbria in laying hens, a preclinical model of spontaneous ovarian cancer

Ovarian high grade serous carcinoma (HGSC) is a lethal form of ovarian cancer (OVCA). In most cases it is detected at late stages as the symptoms are non-specific during early stages. Emerging information suggests that the oviductal fimbria is a site of origin of ovarian HGSC. Currently available tests cannot detect ovarian HGSC at early stage. The lack of a preclinical model with oviductal fimbria that develops spontaneous ovarian HGSC is a significant barrier to developing an early detection test for this disease. The goal of this study was to examine if the oviductal fimbria in hens is a site of origin of HGSC and whether it expresses several putative markers expressed in ovarian HGSC in patients. A total of 135 laying hens (4 years old) were selected from a flock using transvaginal ultrasound (TVUS) imaging, followed by euthanasia and gross examination for the presence of solid masses and ascites. Histological types of carcinomas were determined by hematoxylin and eosin staining. Expression of WT-1, mutant p53, CA-125, PAX2 and Ki67 in normal or malignant fimbriae or ovaries were examined using immunohistochemistry, immunoblotting and gene expression assays. This study detected tumors in oviductal fimbriae in hens and routine staining revealed ovarian HGSC-like microscopic features in these tumors. These tumors showed similarities to ovarian HGSC in patients in expressing several markers. Compared with normal fimbriae, intensities of expression of WT-1, mutant p53, CA-125, and Ki67 were significantly (P<0.05) higher in fimbrial tumors. In contrast, expression of PAX2 decreased gradually as the tumor progressed to late stages. The patterns of expression of these markers were similar to those in ovarian HGSC patients. Thus, tumors of the oviductal fimbria in hens may offer a preclinical model to study different aspects of spontaneous ovarian HGSC in women including its early detection.

Optimization of 7,12-dimethylbenz(a)anthracene-induced rat epithelial ovarian tumors

Ovarian carcinoma is the second most common malignant tumor of the female reproductive system and an notable cause of cancer death. The detection and diagnosis of early ovarian carcinomas are still clinical challenges, which calls for imaging studies using early ovarian carcinoma animal models. The present study aimed to optimize the 7,12-dimethylbenz(a)anthracene (DMBA)-induced model of rat ovarian tumors by investigating the delivery methods, induction dose and time of DMBA exposure, and explored the morphological features of tumors using MRI. Three schemes were performed. In scheme one the ovary was covered with absorbable hemostatic gauze loaded with a high concentration of liquid DMBA. For this scheme, 150 Sprague-Dawley rats were divided into three groups depending on the DMBA dose (1.0, 2.0 and 3.0 mg). In scheme two DMBA solution was injected under the ovarian capsule. For this scheme, 159 rats were divided into 0.5, 1.0 and 1.5 mg DMBA groups. In scheme three the ovary was covered with absorbable gauze loaded with a high concentration of solid DMBA. For this scheme 161 rats were divided into 1.0, 2.0 and 3.0 mg DMBA groups. Each group of the three schemes was further subdivided into 60-, 90-, 120-, 150- and 180-day groups. In scheme two, the tumor formation rate was 75.6% (99/131), which was the highest in the 1.5 mg group (86.4%, 38/44) and reached 100% (10/10) on day 120. The induced tumors were serous in 93.9% (93/99) of tumors. Borderline ovarian tumors accounted for 19.2% (19/99) of all tumors, and ovarian cancer accounted for 46.5% (46/99). The mean maximum diameter (MMD) of borderline ovarian tumors was 10.29±3.41 mm, and that of ovarian cancer was 15.19±7.10 mm. MMD of the solid components increased with increasing malignancy. Cystic, cystic-solid and solid tumors were observed. The ovarian subcapsular injection of 1.5 mg DMBA was the best scheme for the rat ovarian tumor model. The present model is ideal for investigating the occurrence, development and imaging of ovarian tumors.

Primary tumors release ITGBL1-rich extracellular vesicles to promote distal metastatic tumor growth through fibroblast-niche formation

Tumor metastasis is a hallmark of cancer. Metastatic cancer cells often reside in distal tissues and organs in their dormant state. Mechanisms underlying the pre-metastatic niche formation are poorly understood. Here we show that in a colorectal cancer (CRC) model, primary tumors release integrin beta-like 1 (ITGBL1)-rich extracellular vesicles (EVs) to the circulation to activate resident fibroblasts in remote organs. The activated fibroblasts induce the pre-metastatic niche formation and promote metastatic cancer growth by secreting pro-inflammatory cytokine, such as IL-6 and IL-8. Mechanistically, the primary CRC-derived ITGBL1-enriched EVs stimulate the TNFAIP3-mediated NF-κB signaling pathway to activate fibroblasts. Consequently, the activated fibroblasts produce high levels of pro-inflammatory cytokines to promote metastatic cancer growth. These findings uncover a tumor-stromal interaction in the metastatic tumor microenvironment and an intimate signaling communication between primary tumors and metastases through the ITGBL1-loaded EVs. Targeting the EVs-ITGBL1-CAFs-TNFAIP3-NF-κB signaling axis provides an attractive approach for treating metastatic diseases.

Models used to screen for the treatment of multidrug resistant cancer facilitated by transporter-based efflux

PURPOSE

Efflux transporters of the adenosine triphosphate-binding cassette (ABC)-superfamily play an important role in the development of multidrug resistance (multidrug resistant; MDR) in cancer. The overexpression of these transporters can directly contribute to the failure of chemotherapeutic drugs. Several in vitro and in vivo models exist to screen for the efficacy of chemotherapeutic drugs against MDR cancer, specifically facilitated by efflux transporters.

RESULTS

This article reviews a range of efflux transporter-based MDR models used to test the efficacy of compounds to overcome MDR in cancer. These models are classified as either in vitro or in vivo and are further categorised as the most basic, conventional models or more complex and advanced systems. Each model's origin, advantages and limitations, as well as specific efflux transporter-based MDR applications are discussed. Accordingly, future modifications to existing models or new research approaches are suggested to develop prototypes that closely resemble the true nature of multidrug resistant cancer in the human body.

CONCLUSIONS

It is evident from this review that a combination of both in vitro and in vivo preclinical models can provide a better understanding of cancer itself, than using a single model only. However, there is still a clear lack of progression of these models from basic research to high-throughput clinical practice.

RNA-Seq transcriptome analysis shows anti-tumor actions of melatonin in a breast cancer xenograft model

Melatonin is a pleiotropic anti-cancer molecule that controls cancer growth by multiple mechanisms. RNA-Seq can potentially evaluate therapeutic response and its use in xenograft tumor models can differentiate the changes that occur specifically in tumor cells or in the tumor microenvironment (TME). Melatonin actions were evaluated in a xenograft model of triple-negative breast cancer. Balb/c nude mice bearing MDA-MB-231 tumors were treated with melatonin or vehicle. RNA-Seq was performed on the Illumina HiSeq. 2500 and data were mapped against human and mouse genomes separately to differentiate species-specific expression. Differentially expressed (DE) genes were identified and Weighted Gene Co-expression Network Analysis (WGCNA) was used to detect clusters of highly co-expressed genes. Melatonin treatment reduced tumor growth (p < 0.01). 57 DE genes were identified in murine cells, which represented the TME, and were mainly involved in immune response. The WGCNA detected co-expressed genes in tumor cells and TME, which were related to the immune system among other biological processes. The upregulation of two genes (Tnfaip8l2 and Il1f6) by melatonin was validated in the TME, these genes play important roles in the immune system. Taken together, the transcriptomic data suggests that melatonin anti-tumor actions occur through modulation of TME in this xenograft tumor model.

Orientation of Preclinical Research in Ovarian Cancer

OBJECTIVES

A large variety of mouse models for cancer exist, also in the field of ovarian cancer. Each model possesses different features, which makes it difficult to interpret their translational value. This review provides an overview of the available ovarian cancer mouse models and their possible use in search for new treatments.

METHODS

This was a PubMed search of available literature on genetically engineered mouse models, xenografts, transplantable models, and immunocompetent mouse models in ovarian cancer, with a specific focus on clinically relevant features of the described models.

RESULTS/CONCLUSIONS

Several preclinical models are available for ovarian cancer. Based on their properties, a model should be carefully selected as a function of the experimental setup to achieve clinically relevant results.

Ficus umbellata Vahl. (Moraceae) Stem Bark Extracts Exert Antitumor Activities In Vitro and In Vivo

A Ficus umbellata is used to treat cancer. The present work was therefore designed to assess antitumor potentials of F. umbellata extracts in nine different cell lines. Cell cycle, apoptosis, cell migration/invasion, levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), caspases activities as well as Bcl-2 and Bcl-xL protein content were assessed in MDA-MB-231 cells. The 7,12-dimethylbenz(a)anthracene (DMBA)-induced carcinogenesis in rats were also used to investigate antitumor potential of F. umbellata extracts. The F. umbellata methanol extract exhibited a CC50 of 180 μg/mL in MDA-MB-231 cells after 24 h. It induced apoptosis in MCF-7 and MDA-MB-231 cells, while it did not alter their cell cycle phases. Further, it induced a decrease in MMP, an increase in ROS levels and caspases activities as well as a downregulation in Bcl-2 and Bcl-xL protein contents in MDA-MB-231 cells. In vivo, F. umbellata aqueous (200 mg/kg) and methanol (50 mg/kg) extracts significantly (p < 0.001) reduced ovarian tumor incidence (10%), total tumor burden (58% and 46%, respectively), average tumor weight (57.8% and 45.6%, respectively) as compared to DMBA control group. These results suggest antitumor potential of F. umbellata constituents possibly due to apoptosis induction mediated through ROS-dependent mitochondrial pathway.

Athymic nude mice as an experimental model for cancer treatment

Athymic nude mice, a murine strain bearing spontaneous deletion in the Foxn1 gene that causes deteriorated or absent thymus (which results in inhibited immune system with reduction of number of T cells), represent a widely used model in cancer research having long lasting history as a tool for preclinical testing of drugs. The review describes three models of athymic mice that utilize cancer cell lines to induce tumors. In addition, various methods that can be applied in order to evaluate activity of anticancer agents in these models are shown and discussed. Although each model has certain disadvantages, they are still considered as inevitable instruments in many fields of cancer research, particularly in finding new drugs that would more effectively combat the cancer disease or enhance the use of current chemotherapy. Finally, the review summarizes strengths and weaknesses as well as future perspectives of the athymic nude mice model in cancer research.

Discovery of prognostic factors for diagnosis and treatment of epithelial-derived ovarian cancer from laying hens

Ovarian cancer is a lethal gynecological cancer causing cancer-related deaths in women worldwide. It is difficult to diagnosis at an early stage when more than 90% patients can be cured because of lack of specific symptoms and early detection markers. Most of malignant ovarian tumors are originated from the germinal epithelium of the ovary. For investigation with animal models of epithelial-derived ovarian cancer (EOC), laying hens are the most relevant animal models because they spontaneously develop EOC as occurs in women through ovulating almost every day. As in women, EOC in the hen is age-related and grossly and histologically similar to that in women. However, domesticated animals are inappropriate for research human EOC due to multiple pregnancies and lactating or seasonally anestrous. In addition, the non-spontaneous nature of rodents EOC limits clinical relevance with human EOC. Recent studies have shown that ovarian cancer could arise from epithelium from the oviduct as oviduct-related genes are up-regulated in EOC of hens. Therefore, we showed in the review: 1) characterization and classification of EOC; 2) chicken models for EOC; 3) relationship estrogen with EOC; 4) candidate prognostic factors for EOC including serpin peptidase inhibior, clade B (ovalbumin), member 3 (SERPINB3), SERPINB11, gallicin 11 (GAL11), secreted phosphoprotein 1 (SPP1) and alpha 2 macroglobulin (A2M) in normal and cancerous ovaries of laying hens; 5) biological roles of microRNAs in development of EOC. Collectively, the present reviews indicate that expression of SERPINB3, SERPINB11, GAL11, SPP1 and A2M is clearly associated with the development of ovarian carcinogenesis. These results provide new insights into the prognostic biomarkers for EOC to diagnose and to evaluate responses to therapies for treating EOC of humans.

Epithelial cell tumors of the hen reproductive tract

There is a paucity of preclinical models that simulate the development of ovarian tumors in humans. At present, the egg-laying hen appears to be the most promising model to study the spontaneous occurrence of ovarian tumors in the clinical setting. Although gross classification and histologic grade of tumors have been used prognostically in women with ovarian tumors, there is currently no single system that is universally used to classify reproductive tumors in the hen. Four hundred and one 192-wk-old egg-laying hens were necropsied to determine the incidence of reproductive tumors using both gross pathology and histologic classification. Gross pathologic classifications were designated as follows: birds presenting with ovarian tumors only (class 1), those presenting with oviductal and ovarian tumors (class 2), those with ovarian and oviductal tumors that metastasized to the gastrointestinal tract (class 3), those with ovarian and oviductal tumors that metastasized to the gastrointestinal tract and other distant organs (class 4), those with oviductal tumors only (class 5), those with oviductal tumors that metastasized to other organs with no ovarian involvement (class 6), and those with ovarian tumors that metastasized to other organs with no oviductal involvement (class 7), including birds with gastrointestinal tumors and no reproductive involvement (GI only) and those with no tumors (normal). Histopathologic classifications range from grades 1 to 3 and are based on mitotic developments and cellular differentiation. An updated gross pathology and histologic classification systems for the hen reproductive malignancies provides a method to report the range of reproductive tumors revealed in a flock of aged laying hens.

Characterization of chemically induced ovarian carcinomas in an ethanol-preferring rat model: influence of long-term melatonin treatment

Ovarian cancer is the fourth most common cause of cancer deaths among women, and chronic alcoholism may exert co-carcinogenic effects. Because melatonin (mel) has oncostatic properties, we aimed to investigate and characterize the chemical induction of ovarian tumors in a model of ethanol-preferring rats and to verify the influence of mel treatment on the overall features of these tumors. After rats were selected to receive ethanol (EtOH), they were surgically injected with 100 µg of 7,12-dimethyl-benz[a]anthracene (DMBA) plus sesame oil directly under the left ovarian bursa. At 260 days old, half of the animals received i.p. injections of 200 µg mel/100 g b.w. for 60 days. Four experimental groups were established: Group C, rats bearing ovarian carcinomas (OC); Group C+EtOH, rats voluntarily consuming 10% (v/v) EtOH and bearing OC; Group C+M, rats bearing OC and receiving mel; and Group C+EtOH+M, rats with OC consuming EtOH and receiving mel. Estrous cycle and nutritional parameters were evaluated, and anatomopathological analyses of the ovarian tumors were conducted. The incidence of ovarian tumors was higher in EtOH drinking animals 120 days post-DMBA administration, and mel efficiently reduced the prevalence of some aggressive tumors. Although mel promoted high EtOH consumption, it was effective in synchronizing the estrous cycle and reducing ovarian tumor mass by 20%. While rats in the C group displayed cysts containing serous fluid, C+EtOH rats showed solid tumor masses. After mel treatment, the ovaries of these rats presented as soft and mobile tissues. EtOH consumption increased the incidence of serous papillary carcinomas and sarcomas but not clear cell carcinomas. In contrast, mel reduced the incidence of sarcomas, endometrioid carcinomas and cystic teratomas. Combination of DMBA with EtOH intake potentiated the incidence of OC with malignant histologic subtypes. We concluded that mel reduces ovarian masses and the incidence of adenocarcinomas in ethanol-deprived rats.

Immune cells in the normal ovary and spontaneous ovarian tumors in the laying hen (Gallus domesticus) model of human ovarian cancer

Background

Spontaneous ovarian cancer in chickens resembles human tumors both histologically and biochemically. The goal was to determine if there are differences in lymphocyte content between normal ovaries and ovarian tumors in chickens as a basis for further studies to understand the role of immunity in human ovarian cancer progression.

Methods

Hens were selected using grey scale and color Doppler ultrasound to determine if they had normal or tumor morphology. Cells were isolated from ovaries (n = 6 hens) and lymphocyte numbers were determined by flow cytometry using antibodies to avian CD4 and CD8 T and B (Bu1a) cells. Ovarian sections from another set of hens (n = 26) were assessed to verify tumor type and stage and to count CD4, CD8 and Bu1a immunostained cells by morphometric analysis.

Results

T and B cells were more numerous in ovarian tumors than in normal ovaries by flow cytometry and immunohistochemistry. There were less CD4+ cells than CD8+ and Bu1a+ cells in normal ovaries or ovarian tumors. CD8+ cells were the dominant T cell sub-type in both ovarian stroma and in ovarian follicles compared to CD4+ cells. Bu1a+ cells were consistently found in the stroma of normal ovaries and ovarian tumors but were not associated with follicles. The number of immune cells was highest in late stage serous tumors compared to endometrioid and mucinous tumors.

Conclusions

The results suggest that similar to human ovarian cancer there are comparatively more immune cells in chicken ovarian tumors than in normal ovaries, and the highest immune cell content occurs in serous tumors. Thus, this study establishes a foundation for further study of tumor immune responses in a spontaneous model of ovarian cancer which will facilitate studies of the role of immunity in early ovarian cancer progression and use of the hen in pre-clinical vaccine trials.

Hypermethylation and post-transcriptional regulation of DNA methyltransferases in the ovarian carcinomas of the laying hen

DNA methyltransferases (DNMTs) are key regulators of DNA methylation and have crucial roles in carcinogenesis, embryogenesis and epigenetic modification. In general, DNMT1 has enzymatic activity affecting maintenance of DNA methylation, whereas DNMT3A and DNMT3B are involved in de novo methylation events. Although DNMT genes are well known in mammals including humans and mice, they are not well studied in avian species, especially the laying hen which is recognized as an excellent animal model for research on human ovarian carcinogenesis. Results of the present study demonstrated that expression of DNMT1, DNMT3A and DNMT3B genes was significantly increased, particularly in the glandular epithelia (GE) of cancerous ovaries, but not normal ovaries. Consistent with this result, immunoreactive 5-methylcytosine protein was predominantly abundant in nuclei of stromal and GE cells of cancerous ovaries, but it was also found that, to a lesser extent, in nuclei of stromal cells of normal ovaries. Methylation-specific PCR analysis detected hypermethylation of the promoter regions of the tumor suppressor genes in the initiation and development of chicken ovarian cancer. Further, several microRNAs, specifically miR-1741, miR-16c, and miR-222, and miR-1632 were discovered to influence expression of DNMT3A and DNMT3B, respectively, via their 3′-UTR which suggests post-transcriptional regulation of their expression in laying hens. Collectively, results of the present study demonstrated increased expression of DNMT genes in cancerous ovaries of laying hens and post-transcriptional regulation of those genes by specific microRNAs, as well as control of hypermethylation of the promoters of tumor suppressor genes.

Resveratrol exerts differential effects in vitro and in vivo against ovarian cancer cells

Epithelial ovarian cancer represents the most lethal gynecological cancer, and the high mortality rate makes this malignancy a major health concern. Poor prognosis results from an inability to detect ovarian cancers at an early, curable stage, as well as from the lack of an effective therapy. Thus, effective and novel strategies for prevention and treatment with non-toxic agents merit serious consideration. Resveratrol, obtained from grapes, berries, peanuts and red wine, has been shown to have a potent growth-inhibitory effect against various human cancer cells as well as in in vivo preclinical cancer models. The objective here was to evaluate potential antitumor effects of resveratrol in both in vitro and in vivo NuTu-19 ovarian cancer models. In vitro an invasion assay was performed. After 48 h, the numbers of viable cells that invaded the extracellular matrix layer were reduced by 94% with resveratrol in comparison to control. For the in vivo anti-tumor assessment, 10 rats were injected with NuTu-19 cells into the ovarian bursa. Thereafter, half were provided with a diet mixed with a dose of 100 mg resveratrol/kg body weight/day for 28 days. Following sacrifice, anticancer effects were assessed by histological evaluation of ovarian as well as surrounding tissues, and immunohistochemical detection of cell proliferation and apoptosis, but there were no observable differences between the control and resveratrol-treated groups for any of the biological endpoints. While resveratrol is effective in suppressing the in vitro cellular invasion of NuTu-19 ovarian cancer cells, these effects do not appear to impact on in vivo NuTu-19 ovarian cancers in rats.

Immunotherapy in new pre-clinical models of HPV-associated oral cancers

Cervical, anal, penile and a sub-set of head and neck (HN) tumors are critical health problems caused by high risk Human Papilloma Viruses (HPVs), like HPV type 16. No specific/effective pharmacological treatments exist. A valid preventive vaccination as well as the immunotherapy of persistent infections, pre-cancerous lesions or early-stage cancers could drive the HPV disease burden down. These treatments might be featured through low-cost platforms like those based on DNA and plant biotechnologies to produce tailored and enhanced formulations taking profit from the use of plants as bio-factories and as a source of immune-stimulators. Finally, and regardless of the formulation type, pre-clinical tests and models are crucial to foresee efficacy of immunotherapy before clinical trials.   In this study, we created an orthotopic mouse model for HPV-related oral tumors, a subset of HN tumors for which no models have been generated before. The model was obtained by inducing the stable expression of the HPV16 E7 protein into the mouse oral squamous cell carcinoma (OSCC) AT-84 (AT-84 E7). The AT-84 E7 cells were injected into the mouth pavement of C3H mice via an extra-oral route to obtain orthotopic tumors. The model turned out to mimic the natural history of the human HPV oral cancer. From AT-84 E7, through engineering to express luciferase, the bioluminescent AT-84 E7-Luc cells were obtained for a fast and easy monitoring by imaging. The AT-84 E7 and the AT-84 E7-Luc tumors were used to test the efficacy of E7-based therapeutic vaccines that we had previously generated and that had been already proven to be active in mice against non-orthotopic E7-expressing tumors (TC-1 cells). In particular, we used genetic and plant-derived formulations based on attenuated HPV16 E7 variants either fused to plant virus genes with immunological activity or produced by tobacco plants. Mice were monitored by imaging allowing to test the size reduction of the mouth implanted experimental tumors in function of the different regimens used. The proposed tumor model is easy to handle and to reproduce and it is efficacious in monitoring immunotherapy. Furthermore, it is expected to be more predictive of clinical outcome of therapeutic vaccines than non-orthotopic models that are currently used. Finally, imaging offers unique opportunities to predict formulation efficacy through measuring tumor growth in vivo.

Distinct expression pattern and post-transcriptional regulation of cell cycle genes in the glandular epithelia of avian ovarian carcinomas

The cell cycle system is controlled in a timely manner by three groups of cyclins, cyclin dependent kinases and cyclin dependent kinase inhibitors. Abnormal alterations of cell cycle regulatory mechanisms are a common feature of many diseases including numerous tumor types such as ovarian cancer. Although a variety of cell cycle regulatory genes are well known in mammalian species including human and mice, they are not well studied in avian species, especially in laying hens which are recognized as an excellent animal model for research relevant to human ovarian carcinogenesis. Therefore, in the present study, we focused on comparative expression and regulation of expression of candidate genes which might be involved in the cell cycle program in surface epithelial ovarian cancer in laying hens. Our current results indicate that expression levels of cell cycle gene transcripts are greater in cancerous as compared to normal ovaries. In particular, cyclin A2 (CCNA2), CCND1, CCND2, CCND3, CCNE2, cyclin dependent kinase 1 (CDK1), CDK3, CDK5, cyclin dependent kinases inhibitor 1A (CDKN1A) and CDKN1B were upregulated predominantly in the glandular epithelia of cancerous ovaries from laying hens. Further, several microRNAs (miRs), specifically miR-1798, miR-1699, miR-223 and miR-1744 were discovered to influence expression of CCND1, CCNE2, CDK1, and CDK3 mRNAs, respectively, via their 3′-UTR which suggests that post-transcriptional regulation of gene expression influences their expression in laying hens. Moreover, miR-1626 influenced CDKN1A expression and miR-222, miR-1787 and miR-1812 regulated CDKN1B expression via their 3′-UTR regions. Collectively, results of the present study demonstrate increased expression of cell cycle-related genes in cancerous ovaries of laying hens and indicate that expression of these genes is post-transcriptionally regulated by specific microRNAs.

SERPINB3 in the chicken model of ovarian cancer: a prognostic factor for platinum resistance and survival in patients with epithelial ovarian cancer

Serine protease inhibitors (SERPINs) appear to be ubiquitously expressed in a variety of species and play important roles in pivotal physiological processes such as angiogenesis, immune responses, blood coagulation and fibronolysis. Of these, squamous cell carcinoma antigen 1 (SCCA1), also known as a SERPINB3, was first identified in squamous cell carcinoma tissue from the cervix of women. However, there is little known about the SERPINB3 expression in human epithelial ovarian cancer (EOC). Therefore, in the present study, we investigated the functional role of SERPINB3 gene in human EOC using chickens, the most relevant animal model. In 136 chickens, EOC was found in 10 (7.4%). SERPINB3 mRNA was induced in cancerous, but not normal ovaries of chickens (P<0.01), and it was abundant only in the glandular epithelium of cancerous ovaries of chickens. Further, several microRNAs, specifically miR-101, miR-1668 and miR-1681 were discovered to influence SERPINB3 expression via its 3′-UTR which suggests that post-transcriptional regulation influences SERPINB3 expression in chickens. SERPINB3 protein was localized predominantly to the glandular epithelium in cancerous ovaries of chickens, and it was abundant in the nucleus of both chicken and human ovarian cancer cell lines. In 109 human patients with EOC, 15 (13.8%), 66 (60.6%) and 28 (25.7%) patients showed weak, moderate and strong expression of SERPINB3 protein, respectively. Strong expression of SERPINB3 protein was a prognostic factor for platinum resistance (adjusted OR; odds ratio, 5.94; 95% Confidence Limits, 1.21–29.15), and for poor progression-free survival (PFS; adjusted HR; hazard ratio, 2.07; 95% CI; confidence interval, 1.03–4.41). Therefore, SERPINB3 may play an important role in ovarian carcinogenesis and be a novel biomarker for predicting platinum resistance and a poor prognosis for survival in patients with EOC.

Chicken pleiotrophin: regulation of tissue specific expression by estrogen in the oviduct and distinct expression pattern in the ovarian carcinomas

Pleiotrophin (PTN) is a developmentally-regulated growth factor which is widely distributed in various tissues and also detected in many kinds of carcinomas. However, little is known about the PTN gene in chickens. In the present study, we found chicken PTN to be highly conserved with respect to mammalian PTN genes (91–92.6%) and its mRNA was most abundant in brain, heart and oviduct. This study focused on the PTN gene in the oviduct where it was detected in the glandular (GE) and luminal (LE) epithelial cells. Treatment of young chicks with diethylstilbesterol induced PTN mRNA and protein in GE and LE, but not in other cell types of the oviduct. Further, several microRNAs, specifically miR-499 and miR-1709 were discovered to influence PTN expression via its 3′-UTR which suggests that post-transcriptional regulation influences PTN expression in chickens. We also compared expression patterns and CpG methylation status of the PTN gene in normal and cancerous ovaries from chickens. Our results indicated that PTN is most abundant in the GE of adenocarcinoma of cancerous, but not normal ovaries of hens. Bisulfite sequencing revealed that 30- and 40% of −1311 and −1339 CpG sites are demethylated in ovarian cancer cells, respectively. Collectively, these results indicate that chicken PTN is a novel estrogen-induced gene expressed mainly in the oviductal epithelia implicating PTN regulation of oviduct development and egg formation, and also suggest that PTN is a biomarker for epithelial ovarian carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease.

Avian SERPINB11 gene: a marker for ovarian endometrioid cancer in chickens

As serine and cysteine proteinase inhibitors, serpins, such as SERPINB5, cause ovarian, colorectal and pancreatic adenocarcinomas. We identified SERPINB11 as a novel estrogen-induced gene in chickens during oviduct development. The chicken is a unique animal model for research on human ovarian cancer, because it spontaneously develops epithelial cell-derived ovarian cancer as in women. Therefore, this study investigated the expression pattern, CpG methylation status, and miRNA regulation of the SERPINB11 gene in normal and cancerous ovaries from chickens. Our results indicate that SERPINB11 is most abundant in the glandular epithelium of endometrioid adenocarcinoma of cancerous, but not normal, ovaries of hens. In addition, bisulfite sequencing revealed that about 30% of -110 CpG sites are methylated in ovarian cancer cells, whereas -110 CpG sites are demethylated in normal ovarian cells. Next, we determined whether miR-1582 influences SERPINB11 expression via its 3'UTR and found that it does not directly target the 3'UTR of SERPINB11 mRNA. Therefore, it is unlikely that post-transcriptional regulation influences SERPINB11 expression in the chicken ovary. On the other hand, in human ovarian cancer cells such as OVCAR-3, SKOV-3 and PA-1 cells, immunoreactive SERPINB11 protein was predominant in the cytoplasm and had a similar expression pattern to that in chicken ovarian cancer cells. Collectively, these results suggest that SERPINB11 is a biomarker for chicken ovarian endometrioid carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease in women.

Differential expression of alpha 2 macroglobulin in response to dietylstilbestrol and in ovarian carcinomas in chickens

BACKGROUND

Alpha 2 macroglobulin (A2M; also known as ovostatin), a homotetrameric protein with four disulfide-linked subunits, has the unique feature of inactivating/inhibiting most known proteases including serine-, threonine-, cysteine-, aspartic- and metalloproteases. In chickens, A2M has been identified and characterized biochemically, but little is known of its functional role(s) in the oviduct, hormonal regulation of expression or its expression in ovarian carcinomas in chickens. Therefore, we investigated estrogen regulation of A2M gene expression during development of the chicken oviduct, and its expression in normal and cancerous ovaries from chickens.

METHODS

To determine tissue-specific expression of A2M in chickens, we collected various organs from male and female chickens and performed RT-PCR analyses. To examine A2M gene expression in the oviduct of 1-week-old female chicks that received a subcutaneous implant of 15 mg DES in the abdominal region for 20 days, we performed RT-PCR, qPCR and in situ hybridization analyses using cDNAs from control- (n=5) and DES-treated oviducts (n=5), and then each segment of the oviduct from DES-treated chicks. To determine if A2M is a biomarker of ovarian cancer in hens, we collected cancerous (n=10) ovaries from a total of 136 chickens which had completely stopped egg-laying and performed RT-PCR and in situ hybridization analyses.

RESULTS

We found that A2M is most abundant in the chicken oviduct, specifically luminal (LE) and glandular epithelia (GE), but it was not detected in any other tissues of either sex. We then determined that DES (dietylstilbestrol, a synthetic nonsteroidal estrogen) increased A2M mRNA only in LE and GE of the oviduct of chicks. Further, expression of A2M was most abundant in GE of endometrioid adenocarcinoma of cancerous, but not normal ovaries of hens.

CONCLUSIONS

Collectively, results of the present study indicate that A2M is novel estrogen-stimulated gene expressed in LE and GE of the chicken oviduct and may be used for monitoring effects of therapies for ovarian cancer in laying hens.

The hen model of human ovarian cancer develops anti-mesothelin autoantibodies in response to mesothelin expressing tumors

Objective

Study of the hen immune system led to seminal contributions to basic immunological principles. Recent studies of spontaneous ovarian cancer in the laying hen show strikingly similar tumor types and antigen expression compared to human ovarian cancer, suggesting hens would be valuable for studies of tumor immunology and pre-clinical vaccine development. Circulating mesothelin is a relatively specific marker for human ovarian cancer and autoantibodies to mesothelin were reported. We hypothesized that hen tumors express mesothelin and that circulating anti-mesothelin antibodies occur in response to tumors.

Methods

Mesothelin mRNA expression was analyzed by RT-PCR in hen ovarian tumors and normal ovaries. Mesothelin protein expression was evaluated by immunohistochemistry (IHC) and two-dimensional SDS-PAGE Western blots. Anti-mesothelin antibodies were assessed by immunoassay of sera from hens with normal ovaries and with ovarian tumors.

Results

Significant mesothelin mRNA expression was observed in 57% (12/21) of hen ovarian tumors but not in normal ovaries and was found predominantly in serous tumors as in humans. Mesothelin protein was detected in tumors with mesothelin mRNA by IHC and 2D Western blots, but not in normal ovaries or tumors without mesothelin mRNA. Circulating anti-mesothelin antibodies occurred in 44% (n = 4/9) of hens with ovarian tumors which express mesothelin mRNA and were not found in hens with tumors that did not express mesothelin (n = 0/5) or normal ovaries (n = 0/5).

Conclusion

The results support the utility of the hen as a novel model for preclinical studies of mesothelin as a biomarker and a target for immunotherapy.

Contrast-enhanced sonography depicts spontaneous ovarian cancer at early stages in a preclinical animal model

OBJECTIVE

Our goal was to examine the feasibility of using laying hens, a preclinical model of human spontaneous ovarian cancer, in determining the kinetics of an ultrasound contrast agent indicative of ovarian tumor-associated neoangiogenesis in early-stage ovarian cancer.

METHODS

Three-year-old White Leghorn laying hens with decreased ovarian function were scanned before and after intravenous injection of a human serum albumin-perflutren contrast agent at a dose of 5 μL/kg body weight. Gray scale morphologic characteristics, Doppler indices, the arrival time, peak intensity, and wash-out of the contrast agent were recorded and archived on still images and video clips. Hens were euthanized thereafter; sonographic predictions were compared at gross examination; and ovarian tissues were collected. Archived clips were analyzed to determine contrast parameters and Doppler intensities of vessels. A time-intensity curve per hen was drawn, and the area under the curve was derived. Tumor types and the density of ovarian microvessels were determined by histologic examination and immunohistochemistry and compared to sonographic predictions.

RESULTS

The contrast agent significantly (P < .05) enhanced the visualization of microvessels, which was confirmed by immunohistochemistry. Contrast parameters, including the time of wash-out and area under the curve, were significantly different (P < .05) between ovaries of normal hens and hens with ovarian cancer and correctly detected cancer at earlier stages than the time of peak intensity.

CONCLUSIONS

The laying hen may be a useful animal model for determining ovarian tumor-associated vascular kinetics diagnostic of early-stage ovarian cancer using a contrast agent. This model may also be useful for testing the efficacy of different contrast agents in a preclinical setting.

Detection of tumor-associated neoangiogenesis by Doppler ultrasonography during early-stage ovarian cancer in laying hens: a preclinical model of human spontaneous ovarian cancer

OBJECTIVE

Tumor-associated neoangiogenesis (TAN) is one of the earliest events in ovarian tumor growth and represents a potential target for early detection of ovarian cancer (OVCA). Because it is difficult to identify patients with early-stage OVCA, the goal of this study was to explore a spontaneous animal model of in vivo ovarian TAN associated with early-stage OVCA detectable by Doppler ultrasonography (DUS).

METHODS

White Leghorn laying hens were scanned transvaginally at 15-week intervals up to 45 weeks. Gray scale ovarian morphologic characteristics and Doppler indices were recorded. Hens were euthanized at diagnosis for ultrasonographic morphologic/vascular abnormalities or at the end of the study (those that remained normal). Ovarian morphologic and histologic characteristics were evaluated. Vascular endothelial growth factor (VEGF) and alpha(v)beta(3)-integrin expression was assessed by immunohistochemical analysis. Doppler ultrasonographic observations were compared with histologic and immunohisto-chemical findings to determine the ability of DUS to detect ovarian TAN.

RESULTS

Significant changes in ovarian blood flow parameters were observed during transformation from normal to tumor development in the ovary (P < .05). Tumor-related changes in ovarian vascularity were identified by DUS before the tumor became detectable by gray scale imaging. Increased expression of VEGF and alpha(v)beta(3)-integrins was associated with tumor development. Ovarian TAN preceded tumor progression in hens.

CONCLUSIONS

The results suggest that ovarian TAN may be an effective target for the detection of early-stage OVCA. The laying hen may also be useful for studying the detection and inhibition of ovarian TAN using various means, including the efficacy of contrast agents, targeted molecular imaging, and antiangiogenic therapies.

Targeting the epidermal growth factor receptor in epithelial ovarian cancer: current knowledge and future challenges

The epidermal growth factor receptor is overexpressed in up to 60% of ovarian epithelial malignancies. EGFR regulates complex cellular events due to the large number of ligands, dimerization partners, and diverse signaling pathways engaged. In ovarian cancer, EGFR activation is associated with increased malignant tumor phenotype and poorer patient outcome. However, unlike some other EGFR-positive solid tumors, treatment of ovarian tumors with anti-EGFR agents has induced minimal response. While the amount of information regarding EGFR-mediated signaling is considerable, current data provides little insight for the lack of efficacy of anti-EGFR agents in ovarian cancer. More comprehensive, systematic, and well-defined approaches are needed to dissect the roles that EGFR plays in the complex signaling processes in ovarian cancer as well as to identify biomarkers that can accurately predict sensitivity toward EGFR-targeted therapeutic agents. This new knowledge could facilitate the development of rational combinatorial therapies to sensitize tumor cells toward EGFR-targeted therapies.

Prevalence of antitumor antibodies in laying hen model of human ovarian cancer

Antitumor antibodies are associated with tumors in human cancers. There is relatively little information on the timing and progression of antibody response to tumors. The objective of the study was to determine if spontaneous ovarian cancer in the egg-laying hen is associated with antitumor antibodies. Antibodies were detected by immunoassay and immunoblotting using proteins from normal ovary and ovarian tumors. Candidate antigens were identified by mass spectrometry of immunoreactive spots cut from 2-dimensional gels and Western blot. Antitumor (serum reacting against tumor ovarian extract) and antiovarian (serum reacting against normal ovarian extract) antibodies were significantly associated with ovarian cancer (67%; P <or= 0.001) compared with normal control hens. Hens with abnormal histology but no gross tumor had antitumor antibodies (63%; P <or= 0.025) but not antiovarian antibodies. There were common as well as different immunoreactions against normal ovary and homologous and heterologous tumor proteins in 2-dimensional Western blots. The candidate antigens included those commonly associated with human cancers and other diseases such as vimentin, apolipoprotein A1, Annexin II, enolase, DJ-1, and so on. The results suggest that antitumor antibodies are associated with ovarian cancer in hens, similar to human ovarian cancer. The egg-laying hen may be a model for understanding the antitumor humoral immune response, particularly at early tumor stages that are not readily accessible in human ovarian cancer.

Histopathology of ovarian tumors in laying hens: a preclinical model of human ovarian cancer

The high mortality rate due to ovarian cancer (OVCA) is attributed to the lack of an effective early detection method. Because of the nonspecificity of symptoms at early stage, most of the OVCA cases are detected at late stages. This makes the access to women with early-stage disease problematic and presents a barrier to development and validation of tests for detection of early stage of OVCA in humans. Animal models are used to elucidate disease etiologies and pathogenesis that are difficult to study in humans. Laying hen is the only available animal that develops OVCA spontaneously; however, detailed information on ovarian tumor histology is not available. The goal of this study was to determine the histological features of malignant ovarian tumors in laying hens. A total of 155 young and old (1-5 years of age) laying hens (Gallus domesticus) were selected randomly and evaluated grossly and microscopically for the presence of ovarian tumors. Histological classification of tumors with their stages and grades was determined with reference to those for humans. Similar to humans, all 4 types including serous, endometrioid, mucinous, and clear cell or mixed carcinomas were observed in hen ovarian tumors. Some early neoplastic as well as putative ovarian lesions were also observed. Similarities in histology, metastasis, and stages of hen OVCA to those of humans demonstrate the feasibility of the hen model for additional delineation of the mechanism underlying ovarian carcinogenesis, preclinical testing of new agents for the prevention, and therapy of this disease.

Assessment of acridine orange and SYTO 16 for in vivo imaging of the peritoneal tissues in mice

The effect of peritoneal injection of acridine orange and SYTO 16 in mice was investigated. Images of peritoneal tissues stained with these dyes and obtained through a confocal micro-endoscope are presented. Seventy-five Balb/c mice were split into five groups and given peritoneal injections of dye or saline. The proportions of negative outcomes in each group were compared using confidence intervals and the Fisher's exact statistical test. A statistically significant increase in adverse events due to dye injection was not observed. These data provide an initial investigation into the safety of acridine orange and SYTO 16 for in vivo imaging.

Ovarian neoplasm development by 7,12-dimethylbenz[a]anthracene (DMBA) in a chemically-induced rat model of ovarian failure

OBJECTIVES

The objectives were to determine the time course for ovarian failure in rats caused by 4-vinylcyclohexene diepoxide (VCD) and develop a model for ovarian cancer in which ovarian neoplasms were chemically induced in an animal that was follicle depleted, but retained residual ovarian tissue.

METHODS

Initially, female Fisher 344 rats were treated with VCD (to induce ovarian failure) or vehicle control (sesame oil). Three or 6 months after treatment, ovaries were collected and processed for histological evaluation for confirmation of ovarian failure. A further set of female rats was assigned to four groups exposed to combinations of vehicle control, VCD and/or DMBA (directly applied to the ovary) in a novel model for examining early stages of ovarian neoplasia.

RESULTS

Three and 6 months following VCD dosing there was a significant reduction of ovarian weight and follicle number. Treatment with DMBA subsequent to VCD resulted in tumors in 42% of animals at 3 months and 57% at 5 months. All neoplasms were classified Sertoli-Leydig cell tumors (SLCT). No tumor occurred in animals treated with vehicle or DMBA alone.

CONCLUSIONS

These studies demonstrate that the VCD-treated rat can be used as a model for peri- and post-menopause. DMBA induction of ovarian neoplasms was greater in those rats treated with VCD. Whether this increase was due to tumor initiation by VCD or was the result of ovarian failure cannot be distinguished from these results. This represents the only animal model to date for sex cord stromal tumors.

Detection of ovarian tumors in chicken by sonography: a step toward early diagnosis in humans?

OBJECTIVE

Animal models of spontaneous ovarian cancer are important for understanding early tumor development. Ovarian imaging may play an important role in following changes in tumor development. Laying hens are the only animals that develop spontaneous ovarian cancer similar to humans. The aim of this study was to determine the feasibility of detecting ovarian tumors in laying hens using sonography.

METHODS

Ovaries of commercial strains of White Leghorn laying hens (n = 29, 2.5-3.0 years old) were examined by transvaginal 2-dimensional gray scale and color Doppler sonography. Sonographic evaluations were compared with ovarian anatomy and histologic features.

RESULTS

Results of in vivo sonography and ovarian anatomic and histologic examinations were consistent. The presence of gross ovarian tumors was correctly detected in all hens by sonography. The resistive and pulsatility index values associated with ovarian tumors were lower than for normal ovaries (P < .001) suggesting that blood flow velocity was increased in ovarian tumors. Values associated with abnormal ovarian histologic findings but no gross tumors were intermediate.

CONCLUSIONS

Transvaginal sonography can be used to determine ovarian status in hens. It offers the ability to make repeated examinations on the same hen to monitor early changes in the ovary associated with ovarian cancer.

DT. Targeting lung cancer using an infectivity enhanced CXCR4-CRAd

Conventional treatments are not adequate for the majority of lung cancer patients. Conditionally replicating adenoviruses (CRAds) represent a promising new modality for the treatment of neoplastic diseases, including non-small cell lung cancer. Specifically, following cellular infection, the virus replicates selectively in the infected tumor cells and kills the cells by cytolysis. Next, the progeny virions infect a new population of surrounding target cells, replicate again and eradicate the infected tumor cells while leaving normal cells unaffected. However, to date, there have been two main limitations to successful clinical application of these CRAd agents; i.e. poor infectivity and poor tumor specificity. Here we report the construction of a CRAd agent, CRAd-CXCR4.RGD, in which the adenovirus E1 gene is driven by a tumor-specific CXCR4 promoter and the viral infectivity is enhanced by a capsid modification, RGD4C. This agent CRAd-CXCR4.RGD, as expected, improved both of the viral infectivity and tumor specificity as evaluated in an established lung tumor cell line and in primary tumor tissue from multiple patients. As an added benefit, the activity of the CXCR4 promoter was low in human liver as compared to three other promoters regularly used for targeting tumors. In addition, this agent has the potential of targeting multiple other tumor cell types. From these data, the CRAd-CXCR4.RGD appears to be a promising novel CRAd agent for lung cancer targeting with low host toxicity.

Animal models in oral cancer research

Biologically and clinically relevant animal models are essential in investigation of the progression of diseases and the elaboration of diagnostic or therapeutic protocols. The several rodent models used for in vivo evaluation for oral cancer employ chemical, transplantation and genetic (knockout and transgenic) induction methods. These models are described together with their advantages and disadvantages. Their optimization and application in future research may improve the early detection and treatment of oral cancer.

A novel early-stage orthotopic model for ovarian cancer in the Fischer 344 rat

The purpose of our study was to ascertain the progression of metastases in a novel ovarian cancer model designed to mimic early-stage disease by utilizing an orthotopic injection technique. Female Fischer 344 rats were injected with either 10(4) or 10(5) NuTu-19 cells by intraperitoneal or orthotopic injection. Peritoneal washings and histologic specimens were examined to correlate the incidence and extent of tumor growth. In a second phase, orthotopic injections of 10(2) and 10(3) cells were compared to that of 10(4) cells. Progression of ovarian cancer was observed by gross and microscopic examinations in both intraperitoneal and orthotopic models. Pelvic extension and abdominal adhesions uniquely characterized the orthotopically injected animals. Numbers of identifiable metastases declined with lower cell inocula, confirming that early-stage disease was extended to at least 14 days with 10(2) NuTu-19 cells. The orthotopic ovarian cancer model emulates early disease with the initiation of a primary tumor that is localized within the inherent microenvironment. The orthotopic model offers a clinically relevant alternative for future cancer research that allows for the investigation of therapeutic strategies against early stages of the disease process.

Endogenous Hormones and Ovarian Cancer: Epidemiology and Current Hypotheses

The effect of major epidemiologic risk factors for ovarian cancer has been reviewed in the light of several hormonal hypotheses, including the gonadotropin, androgens, progesterone, estrogens, insulin-like growth factor-I, and insulin hypotheses. The role of inclusion cyst formation and Mullerian epithelium differentiation in the pathology of the disease are also briefly outlined. Although based on limited data, the observed tendency in current evidence suggests possible etiologic roles for elevated androgens and estrogens and decreased progesterone in the pathogenesis of ovarian cancer. A direct effect of gonadotropins cannot be entirely ruled out, but it is plausible that their effect on ovarian cancer risk is mediated by stimulation of ovarian steroidogenesis. Insulin-like growth factor-I also emerges as a hormone that may be directly involved in the pathogenesis of the disease, but thus far only one prospective study has examined this association. Hyperinsulinemia is an unlikely risk factor for ovarian cancer. The observed tendency for an increased risk with androgens from ovarian origin (in premenopausal women), the lack of association with adrenal androgens, and the relatively weak associations observed with obesity, hormonal replacement therapy use, and endogenous hormones after menopause suggest that ovarian synthesis of sex steroids rather than their circulating levels may be etiologically important. More data from prospective studies will be crucial to improve our understanding of the etiologic role of endogenous hormones in the pathogenesis of ovarian cancer. Such data will ultimately provide opportunities for research targeted; at early detection and preventive interventions.

Characterization of a Carcinogenesis Rat Model of Ovarian Preneoplasia and Neoplasia

Animal models of ovarian cancer are crucial for understanding the pathogenesis of the disease and for testing new treatment strategies. A model of ovarian carcinogenesis in the rat was modified and improved to yield ovarian preneoplastic and neoplastic lesions that pathogenetically resemble human ovarian cancer. A significantly lower dose (2 to 5 mug per ovary) of 7,12-dimethylbenz(a)anthracene (DMBA) was applied to the one ovary to maximally preserve its structural integrity. DMBA-induced mutagenesis was additionally combined with repetitive gonadotropin hormone stimulation to induce multiple cycles of active proliferation of the ovarian surface epithelium. Animals were treated in three arms of different doses of DMBA alone or followed by hormone administration. Comparison of the DMBA-treated ovaries with the contralateral control organs revealed the presence of epithelial cell origin lesions at morphologically distinct stages of preneoplasia and neoplasia. Their histopathology and path of dissemination to other organs are very similar to human ovarian cancer. Hormone cotreatment led to an increased lesion severity, indicating that gonadotropins may promote ovarian cancer progression. Point mutations in the Tp53 and Ki-Ras genes were detected that are also characteristic of human ovarian carcinomas. Additionally, an overexpression of estrogen and progesterone receptors was observed in preneoplastic and early neoplastic lesions, suggesting a role of these receptors in ovarian cancer development. These data indicate that this DMBA animal model gives rise to ovarian lesions that closely resemble human ovarian cancer and it is adequate for additional studies on the mechanisms of the disease and its clinical management.