786-O xenograft model
The most common type of kidney cancer is renal cell carcinoma (RCC), accounting for nearly 3 percent of tumors in adults. The exact cause of renal cell carcinoma is currently unknown. Xenograft rodent models are essential in preclinical studies for testing novel therapeutic modalities to address renal cancer. The 786-O epithelial cell line is isolated from primary adenocarcinoma cells of the kidney tissue of a 58-year-old Caucasian male patient with renal cell adenocarcinoma. 786-O is a hypertriploid cell line that produces parathyroid hormone (PTH) and is tumorigenic in nude mice. 786-O cells display both microvilli and desmosomes. The 786-O cell line is invaluable for studying human infections related to the prostate. 786-O is one of the first RCC cell lines that is commonly used in RCC-focused research. A 2013 renal xenograft study published in British Journal of Cancer, demonstarates that resistance to sunitinib is accompanied by increased COX-2 expression in areas of tumor hypoxia in the 786-O xenograft model. Also, the COX-2 inhibitor celecoxib enhances the effectiveness of sunitinib in the 786-O xenograft model by delaying time to progression if administered early in the course of sunitinib therapy. Celecoxib showed activity in the 786-O tumor model as a single agent and in combination with sunitinib. The 786-O RCC line expresses high levels of VEGF (Vascular endothelial growth factor), which stimulates angiogenesis and gives rise to tumors in nude mice. Rap2B can promote angiogenesis through PI3K/AKT pathway in vivo, and loss of Rap2B could be a novel strategy for RCC anti-angiogenesis therapy, as per a 2017 study in Tumor Biology. The 786-O cell line (human kidney) is used to create the CDX (Cell Line Derived Xenograft) 786-O xenograft mouse model that allows researchers to study COX-2 inhibitors and anti-angiogenesis therapy as well as anti-cancer agents targeting RCC cells.
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Basic study design
1. 786-O cells are cultured under asceptic conditions in exponential growth phase prior to injection.
2. The cells are trypsinized from the flasks and viable cell counts are determined using a trypan blue exclusion assay (98% cell viability required). The cell suspension is adjusted to the appropriate density.
3. Each mouse (athymic BALB/C or NOD/SCID, 10-12 w.o.) receive a subcutaneous injection in the flank of the hind leg of one million cells in a volume of 100 microliters of matrigel 786-O cell suspension
4. The injection sites are manually palpated three times weekly until tumors are established. Tumors are measured using digital calipers until they reach an average size of 50-150 mm3.
5. Animals are randomized into treatment cohorts and administration of the compound of interest is performed according to the treatment schedule.
6. Tumors are measured daily and mouse weights recorded 3 times weekly.
7. Animals are euthanized when tumor size reaches 2,000 sq millimeters or the predetermined size limit.
8. Necropsy and tissue collections are performed as defined for termination of experiment.
9. Tumors are excised, weighed and documented by digital imaging.
10. Standard gross necropsies are performed and tissues are collected for downstream analysis.
11. Tumors and tissues are snap frozen in LN2 and prepared for histology or gene expression analysis.
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 786-O xenograft model:
- 786-O Tumor Growth Delay (TGD; latency)
- 786-O 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)
- 786-O 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