MC38 xenograft model
Colorectal cancer (CRC) is the second leading cause of cancer deaths worldwide. Colon cancer models in rodents are valuable tools for the preclinical assessment of novel therapeutic agents. Also, murine models are useful for studying the fundamental properties of tumors and aid in the investigation of pathophysiologic mechanisms of CRC development. The MC38 tumorigenic epithelial cell line is isolated from mice with colon adenocarcinoma and expresses high levels of human carcinoembryonic antigen (CEA). The MC38 cell line (mouse colon) is used to create the CDX (Cell Line Derived Xenograft) MC38 xenograft mouse model. The MC38 xenograft model studies include stimulated proliferation of colon cancer due to exogenous insulin, along with standard anti-tumor studies (e.g. 5-FU, PRI-2191, cathepsin S inhibitors).
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Basic study design
- MC38 cells are maintained at a growth rate of exponential growth leading up to injection. Cells are prepared by trypsinization, with viable cell counts determined via standard trypan blue exclusion with a minimum viability of 98% required.
- The cell suspension is diluted and each mouse (athymic BALB/c (nu/nu), 12 w.o.) is injected subcutaneously in the flank of a hind leg. The injection contains one million cells of matrigel + MC38 in a volume of 100 uL.
- Palpation of injection sites occur three times weekly until tumor establishment. Tumors are then calipered until an average size of 50-150 mm3 is reached.
- Animals are sorted into treatment groups; administration of test compounds are performed according to the client schedule.
- Tumors are measured daily and mouse weights recorded (up to 3 times a week).
- Animals are euthanized as tumor size reaches 2,000 cu millimeters, or the end of study size limit. Tissue collections are performed. The tumors are excised and weighed, then documented by imaging.
- Standard necropsies are performed. Tissues are collected for downstream analysis and can be snap frozen in LN2 or nucleic acids isolated.
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 acclimatization 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 MC38 xenograft model:
- MC38 Tumor Growth Delay (TGD; latency)
- MC38 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)
- MC38 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