SK-N-AS xenograft model
Neuroblastoma is the most common extracranial solid tumor in children; roughly half of the patients experience bone metastasis accompanied by bone pain, leading to poor prognosis where long term survival of high-risk patients is below 40%. The SK-N-AS is hyperdiploid cell line derived from a bone marrow metastasis of a 6-year old female patient. According to a 1989 article in the Journal of Clinical Investigation, SK-N-AS cells taken from human neuroblastoma replicate autonomously due to stimulation by IGF-2. The SK-N-AS cell line produces large amounts of IGF-2 and expresses type 1 insulin-like growth factor receptors. SK-N-AS cells can be useful in the preclinical investigative research for several types of brain cancer. Polo-like kinase 1 (PLK1) is overexpressed in many cancers including high-risk neuroblastoma and is linked to unfavorable patient outcome; a 2011 study by Ackermann et al. demonstrated the strong antitumor activity of the PLK1 inhibitor BI 2536 using this SK-N-AS xenograft mouse model. A 2014 study in the Journal of Bone Oncology by Tsutsuminmoto et al. used the SK-N-AS xenograft model to investigate the mechanism of bone metastasis in neuroblastoma. They found that SK-N-AS cells, but not other neuroblastoma cells, induced expression of the receptor activator of NF-κB ligand, expressed COX-2 mRNA and produced high levels of prostaglandin E2 (PGE2); these phenotypes were suggested to be critical for osteoclastogenesis and developing bone metastases. In 2016, Beadry et al. released a study in the Pedatric Blood Cancer journal using the SK-N-AS xenograft mouse model; this study demonstrated the successful differentiation of high-risk from low-risk patients in addition to active disease from complete response (CR) to very good partial response (VGPR) patients by using serum metabolomics analysis (differences were observed in amino acid, nitrogen, ketosis and carbohydrate metabolism). They concluded that this technique can potentially predict neuroblastoma behavior in humans and allow for improvement and fine-tuning of therapy regimens.
Altogen Labs provides customizable xenotransplantation services for SK-N-AS cells that include comprehensive metabolic assay reports. The SK-N-AS cell line is used to create the CDX (Cell Line Derived Xenograft) SK-N-AS xenograft mouse model. The highly expressing PLK-1 SK-N-AS xenograft is a high-risk neuroblastoma model used to study the anticancer activity of PLK-1 inhibitors (e.g. BI 2536) including mainstream tumor growth inhibitors (e.g. lapatinib, trastuzumab, rosiglitazone).
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Basic study design
- SK-N-AS cells are trypsinized while cell growth is at exponential phase growth. Flow cytometry (Guava PCA) cell viability assay is performed to confirm at least 98% cell viability and measure cell concentration. Total suspension concentration is corrected to the cell density needed for injection.
- Athymic nude mice strain (Foxn1nu/Foxn1+) about 10-12 weeks old receive a single 100 µL injection (subcutaneous) in a hind leg containing one million cells (50% Matrigel + SK-N-AS cell suspension).
- Palpations are performed up to three times a week until tumor establishment. Calipering of tumors are performed to monitor progression of tumor growth. In-life study begins when a size of 50-150 mm3is reached.
- Animals are grouped into client designed cohorts and the test compounds are administered. Tumors are continuously monitored (daily measurements) along with mouse body weights logged.
- The in-life study is terminated when tumor size reaches the study tumor size limit. As directed by the client, tissues are collected and prepared for histology, frozen or nucleic acids isolated. All resected tumors are digitally imaged and weighed.
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.
Xenograft animal models are used to assess the effectiveness of experimental test compounds against specific types of cancer. Novel medicines are tested on staged tumor growths that have been engrafted via subcutaneous or orthotopic inoculation in an immunocompromised mouse or rat model (Nude or NOD/SCID). 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 automated Western Blot WES system (ProteinSimple).
Animal handling and maintenance at the Altogen Labs facilities are 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 SK-N-AS xenograft model:
- SK-N-AS Tumor Growth Delay (TGD; latency)
- SK-N-AS 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)
- SK-N-AS 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