OVCAR-3 xenograft model
Ovarian cancer is the fifth-primary cause of cancer deaths among women, accounting for more fatalities than any other type of cancer in females. Ovarian cancer mostly occurs in older Caucasian women over 60 years old and is one of the deadliest gynecological malignancy worldwide, as indicated by the American Cancer Society. The OVCAR-3 cell line was isolated by Hamilton et al. from the malignant ascites of a patient with progressive adenocarcinoma of the ovary. These cells were characterized in a xenograft model by Hamilton et al. in Cancer Research in 1984, where data demonstrated that mice developed a similar metastatic spread to clinical ovarian cancer and that tumors manifest cytoplasmic estrogen and androgen receptors as well as CA125, the ovarian cancer associated antigen. Similarly, a 2015 study in Gynecology Oncology (Mitra et al.) looked at several frequently used ovarian cancer models, including OVCAR-3, in order to evaluate which cell lines are most reliable for cancer studies. Results looked at tumor formation, ascite formation, histology and immunohistochemistry of PAX8, p53 and WT1 expression and authors used this data to define which models can best represent high-grade serous ovarian cancer (HGSOC). A 2016 study by Park et al. published in Cancer Investigation examined the tumor-suppressive properties of enzalutamide on androgen-driven ovarian cancer in vivo using the OVCAR-3 xenograft model; combination treatment of dihydrotestosterone with enzalutamide led to significant reductions in tumor volume in the OVCAR-3 xenograft model in vivo. These findings indicate that the second-generation antiandrogen enzalutamide could be effective in the treatment of ovarian cancer. The OVCAR-3 cell line (human ovarian) is used for the CDX (Cell Line Derived Xenograft) OVCAR-3 xenograft mouse model. The OVCAR-3 xenograft model is utilized to monitor in vivo tumor growth suppression by alternative therapeutic strategies (e.g. vitamin supplementation EB1089), gene silencing (e.g. claudin-3 siRNA) or small molecules targeting early relapse due to lack of HER2 amplification (e.g. trastuzumab).
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Basic study design
- Cells are maintained within a phase of exponential growth and then collected via trypsinization. Viability (trypan blue assay) and cell count (hemacytometer) is determined; cell count of the suspension is adjusted to 10,000 cells/µL. The Matrigel + OVCAR-3 cell suspension is injected (100 µL) into the rear flank of athymic BALB/C mice (11 to 12 weeks old).
- As tumors reach 50-150 mm3, mice are sorted into treatment cohorts (randomization). All test compounds are administered in agreement with the study design treatment schedule.
- Tumor measurements (daily) are logged. Whole body weights are determined up to 3 times a week.
- The in-life portion of the study ends when the study design tumor size limit is reached (or there is animal health concerns) per approved IACUC protocol tumor size. Humane euthanization enables tissues/tumors to be collected.
- All removed tumors are weighed and documented. Additionally, tumors can be digitally imaged.
- Tissues collected for downstream analysis are stabilized by snap freezing, stabilization in RNAlater reagent, submersed in 10% NBF or isolation of nucleic acids.
Xenograft animal models are used to assess the effectiveness of drugs against specific types of cancer. New medicines are tested on staged tumor growths that have been engrafted via subcutaneous or orthotopic inoculation in an immunocompromised mouse or rat model. All clinically approved anti-cancer agents have been evaluated with conventional preclinical in vivo models. Xenograft studies can be highly complex, starting with the selection of the appropriate animal model, choice of tumorigenic cell line, administration method, dosing, analysis of tumor growth rates and tumor analysis (histology, mRNA and protein expression levels).
Altogen Labs provides an array of laboratory services using over 30 standard Cell Line Derived Xenograft (CDX) models and over 20 PDX models. Researchers investigating the role of specific proteins or gene products in regulating tumor growth can benefit from development of protein overexpression (genetically engineered to ectopically express proteins, tumor suppressors, or oncogenes) and RNAi cell lines with long term gene silencing. Altogen Labs provides quantitative gene expression analysis of mRNA expression (RT-PCR) and protein expression analysis using the WES system (ProteinSimple).
The dosing of the experimental compound of interest is initiated, for a staged study, when the mean tumor size reaches a specified volume (typically 50-100 mm3). In an unstaged study, the dosing of the compound of interest is initiated immediately after xenografting. Mice are dosed once or twice a day for 28 days (or other desired study duration) via the chosen route of administration. Tumor volume (mm3) is calculated via the “(W x W x L) / 2” formula, where W is tumor width and L is tumor length.
Animal handling and maintenance at the Altogen Labs facility is IACUC-regulated and GLP-compliant. Following acclimation to the vivarium environment, mice are sorted according to body mass. The animals are examined daily for tumor appearance and clinical signs. We provide detailed experimental procedures, health reports and data (all-inclusive report is provided to the client that includes methods, results, discussion and raw data along with statistical analysis). Additional services available include collection of tissue, histology, isolation of total protein or RNA and analysis of gene expression. Our animal facilities have the flexibility to use specialized food or water systems for inducible gene expression systems.
Following options are available for the OVCAR-3 xenograft model:
- OVCAR-3 Tumor Growth Delay (TGD; latency)
- OVCAR-3 Tumor Growth Inhibition (TGI)
- Dosing frequency and duration of dose administration
- Dosing route (intravenous, intratracheal, continuous infusion, intraperitoneal, intratumoral, oral gavage, topical, intramuscular, subcutaneous, intranasal, using cutting-edge micro-injection techniques and pump-controlled IV injection)
- OVCAR-3 tumor immunohistochemistry
- Alternative cell engraftment sites (orthotopic transplantation, tail vein injection and left ventricular injection for metastasis studies, injection into the mammary fat pad, intraperitoneal injection)
- Blood chemistry analysis
- Toxicity and survival (optional: performing a broad health observation program)
- Gross necropsies and histopathology
- Positive control group employing cyclophosphamide, at a dosage of 50 mg/kg administered by intramuscular injection to the control group daily for the study duration
- Lipid distribution and metabolic assays
- Imaging studies: Fluorescence-based whole body imaging, MRI