COLO-205 xenograft model
Colorectal carcinoma (CRC) is the second common cause of cancer-related deaths, mostly occurring in people over 50. Preclinical studies of CRC can help researchers to investigate its correlation with immune response and develop new treatment approaches. The COLO-205 epithelial cell line was isolated by Dr. Semple in 1975 from a 70-year-old Caucasian male patient with colorectal adenocarcinoma after the treatment with 5-fluorouracil for roughly five weeks. The COLO-205 cell line originates from a Dukes’ type D tumor and expresses a 36,000-dalton cell surface glycoprotein. Besides, these cells are negative for expression of CSAp and keratin positive. The COLO-205 cell line is used for researching the SV-40 monkey virus and serves a suitable host for studying colon cancer. Rodent xenograft models share a vast array of characteristics with humans and act as indispensable tools in the development of newer chemotherapeutic drugs. COLO-205 cells are tumorigenic in nude mice and used to create the CDX (Cell Line Derived Xenograft) COLO-205 xenograft mouse model. The COLO-205 colon tumor model is an established model to study the in vivo efficacy of 5-FU or bevacizumab.
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Basic study design
- COLO-205 cells for injection are maintained under asceptic conditions and at exponential growth phase.
- The COLO-205 cells are trypsinized and cell viability determined using a trypan blue exclusion assay (minimum 98% cell viability). The cell suspension is adjusted to appropriate density prior to inoculation.
- Each mouse (athymic BALB/c (nu/nu), 10 weeks old) receives a single subcutaneous injection into the flank of a hind leg containing 1 x 10^6 cells in 100 uL of the matrigel+COLO-205 cell suspension.
- The injection sites are examined three times weekly until tumors are established. Tumors are measured utilizing digital calipers, with optimal starting tumor volumes at an average size of 50-150 mm3.
- Animals are randomized into determined treatment cohorts, with administration of the compound of interest injected according to the treatment schedule.
- Daily, tumors are measured and weights of mice are recorded up to 3 times weekly.
- Animals are euthanized as tumor size approaches either 2,000 sq millimeters or the predetermined tumor size limit.
- A necropsy is performed and tissues collected defined in the termination of experiment.
- Tumors are excised from the animal, weighed and documented using digital imaging.
- A standard gross necropsy is performed and tissues are collected according to customer request for downstream analysis.
- Tumors and/or tissues can be frozen in LN2, prepared for histology or stablized in RNAlater for gene expression analysis.
- Animals were housed in a pathogen-free animal facility in accordance with the Guide for Care and Use of Laboratory Animals, along with the regulations of the Institutional Animal Care and Use Committee (IACUC).
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 COLO-205 xenograft model:
- COLO-205 Tumor Growth Delay (TGD; latency)
- COLO-205 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)
- COLO-205 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