SW480 xenograft model
Colon cancer often affects people in their late 60s-early 70s, per the Colon Cancer Alliance (CCA). Metastasis is typically the most common cause of treatment failure in colorectal cancer patients. Murine xenograft models could facilitate cancer diagnosis and treatment by closely resembling human tumors. The SW480 epithelial cell line is isolated from a colon tumor of a 50-year-old Caucasian male patient with colorectal adenocarcinoma. The SW480 cell line is susceptible to human immunodeficiency virus 1 and expresses elevated levels of p53 protein. Also, SW480 cells positively express c-myc, K-ras, H-ras, N-ras, myb, sis and fos oncogenes. The SW480 cell line is tumorigenic in nude mice and produces carcinoembryonic antigen (CEA) as well as keratin. This model provides a unique research opportunity in that both SW-480 and SW-620 colon cancer lines were taken from primary and secondary tumors of a single patient, as mentioned above; the differences were highlighted in a 2001 study (Hewitt et al.) that reported SW-480 cells have a epitheliod morphology and their xenografts form glandlike structures. In addition SW480, consistent with being of an earlier stage in tumor progression, are less metastatic, tumorigenic and show less resistance anti-FAS or TNF-alpha induced apoptosis. Research that has used the SW480 model include the 2013 study by Shigeta et al. in which data demonstrated anticancer effects of cetuximab, a monoclonal antibody against human epidermal growth factor receptor (EGFR). Results correlated EGFR levels to drug sensitivities in cell lines, confirmed cytotoxic effects of the drug and inhibited growth of tumors in xenograft models; this provides clinical relevance for predicting patient response to cetiximab. The 2016 Oncology Letter publication by Li et al. reported a method for visualizing hypoxia inducible factor 1 alpha in a colorectal cancer xenograft model. The group used a lenti virus for stable transection for cells to dually express HIF-1α and green fluorescent protein (GFP), allowing for efficient screening for the therapeutic potential of HIF-1α targeting drugs. Finally, a 2010 study in Neoplasia (Kaur et al.) used SW480 cells to assess the mechanism of action of silibinin, an active ingredient in milk thistle (Silybum marianum), against colorectal cancer (CRC). Results in vitro as well as xenografts indicated that silibinin decreases proliferation, decreases cyclin D1, β-catenin, CDK8 and c-Myc expression and increases apoptosis in CRC, thereby suggesting its therapeutic potential. SW480 is used to create the CDX (Cell Line Derived Xenograft) SW480 xenograft mouse model. The SW480 xenograft model is a pre-clinical model utilized in studies examining therapeutics targeting the β-catenin pathway (e.g. silibinin). The SW480 model also lends itself to studies addressing the link between human epidermal growth factor receptor (EGFR) expression levels and anti-tumor growth therapies (e.g. cetuximab).
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Basic study design
- Trypan blue exclusion is utilized to determine cell viability and cell count. After cell suspensions are diluted to the appropriate cell density for injection (10,000 cells/µL; injection volume = 100µL containing Matrigel), each immunocompromised mouse (10-12 w.o.) receives a single injection in the flank of the hind leg.
- Tumors are continually calipered (digital) tumor size averages are 50-150 mm3. Treatment cohorts are formed (randomization) the in-life study begins. All drug administration is performed according to the dosing schedule.
- Throughout the study tumors receive daily measurements, along with tri-weekly mouse weights recordings. As the predetermined tumor size is reached, animals are euthanized.
- Collected tissues are stored for downstream analysis (snap frozen, RNAlater, 10% NBF or nucleic acid isolations). Tumor are weights and documented and digital images captured.
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 SW480 xenograft model:
- SW480 Tumor Growth Delay (TGD; latency)
- SW480 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)
- SW480 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