SK-BR-3 Orthotopic Mouse Model Service for Breast Cancer

The SK-BR-3 orthotopic mouse model stands as a cornerstone preclinical platform for interrogating HER2-driven breast cancer biology, enabling researchers to evaluate anti-HER2 therapeutics, dissect resistance mechanisms, and probe tumor-stromal interactions within the physiologically faithful mammary fat pad microenvironment. Alfa Cytology engineers this orthotopic xenograft system with rigorous quality controls and customizable study architectures, empowering your team to generate translationally relevant efficacy and pharmacodynamic datasets for HER2-targeted drug candidates under in vivo conditions that closely mirror the clinical trajectory of HER2-enriched breast malignancies.

Overview of SK-BR-3 Orthotopic Mouse Model for Breast Cancer

The SK-BR-3 cell line was established in 1970 from the pleural effusion of a 43-year-old Caucasian female diagnosed with metastatic breast adenocarcinoma. Genetically catalogued within the HER2-enriched intrinsic subtype, SK-BR-3 is defined by high-level amplification and overexpression of the ERBB2 (HER2/neu) oncogene, coupled with absence of estrogen receptor (ER) and progesterone receptor (PR) expression. The line harbors a mutated TP53 allele and exhibits a hyperdiploid karyotype with complex chromosomal rearrangements. In culture, SK-BR-3 displays epithelial-like morphology with moderate adherence, and retains robust tumorigenic capacity when introduced into immunodeficient hosts. These molecular and biological attributes render SK-BR-3 an indispensable reference standard for HER2 detection assays and a workhorse model for preclinical evaluation of trastuzumab, pertuzumab, T-DM1, and emerging tyrosine kinase inhibitors directed against the HER2 signaling axis.

Fig 1. SKBR3-pool2 cells as compared to the parental SBKR3 cells grew tumors in nude mice with a significantly faster rate and retained trastuzumab resistance phenotype in vivo. (Liu, Hao, et al., 2023)

Orthotopic implantation of SK-BR-3 cells into the murine mammary fat pad reconstitutes the spatial architecture, vascular supply, and stromal crosstalk characteristic of human HER2-positive breast carcinoma, offering marked advantages over subcutaneous counterparts in predicting clinical drug response. Tumors typically establish within 10–14 days post-inoculation and progress to endpoint volumes (approximately 1,000–1,500 mm³) over a 4–6 week observation window. The model supports longitudinal assessment of primary tumor burden via caliper measurement or imaging modalities, while also permitting ex vivo interrogation of metastatic seeding to regional lymph nodes and distant organs. Its particular strength lies in recapitulating the aggressive proliferation kinetics and HER2-addicted signaling circuitry that define the HER2-enriched patient population, making it an essential tool for mechanism-of-action studies and combination regimen optimization in the preclinical space.

Cell Line Information: SK-BR-3

SK-BR-3 is among the most extensively characterized human breast cancer cell lines, serving as a foundational resource for HER2-positive disease research. The table below consolidates its essential biological, genetic, and culture parameters:

Our Services

Alfa Cytology provides comprehensive SK-BR-3 orthotopic model services spanning cell line qualification, surgical implantation, tumor monitoring, therapeutic dosing, and multi-parameter endpoint analysis. Our scientists collaborate closely with your team to align study design with your compound's mechanism of action—whether you are profiling a next-generation HER2 antibody, an antibody-drug conjugate, or a small-molecule kinase inhibitor—delivering robust, audit-ready data packages that advance your discovery pipeline.

Workflow of SK-BR-3 Orthotopic Mouse Model Construction

Construction of the SK-BR-3 orthotopic model follows a streamlined protocol optimized for high engraftment rates, consistent tumor growth trajectories, and seamless integration of treatment and sampling schedules. The procedure unfolds across the following stages:

1. Cell Expansion and Authentication: SK-BR-3 cells are propagated in McCoy's 5A medium with 10% FBS, harvested during logarithmic growth, and subjected to STR profiling for identity confirmation. Mycoplasma negativity is verified by PCR prior to in vivo use. Cells are washed, counted by automated hemocytometer, and resuspended in serum-free medium for injection.
2. Recipient Mouse Selection and Acclimation: Female immunodeficient mice (athymic BALB/c nude or NOD-scid strains, 5–7 weeks old) are quarantined and acclimated for a minimum of 72 hours. Health status is assessed daily, and any mice displaying abnormal behavior or weight loss are excluded from the study prior to cell implantation.
3. Orthotopic Mammary Fat Pad Implantation: Under general anesthesia, a small skin incision is made over the right inguinal mammary fat pad. A single-cell suspension of 5 × 10⁶ SK-BR-3 cells (in 30–50 µL total volume, typically mixed 1:1 with Matrigel) is slowly injected into the fat pad using a 27-gauge needle. The skin is closed with wound clips, and mice recover on a heated pad under observation.
4. Tumor Monitoring and Cohort Stratification: Tumor establishment is monitored by palpation beginning on day 7 post-implantation. Once tumors reach 50–100 mm³, mice are randomized into treatment cohorts based on tumor volume to ensure balanced baseline distributions across all experimental arms.
5. Therapeutic Intervention and Longitudinal Assessment: Test articles are administered according to the predefined protocol (dose, route, frequency, and duration). Tumor dimensions are measured twice weekly with digital calipers, and body weights are recorded concurrently to monitor treatment tolerability. Optional imaging modalities (ultrasound, MRI, or bioluminescence if luciferase-modified cells are used) can be incorporated for non-invasive growth tracking.
6. Necropsy and Tissue Procurement: Upon reaching study endpoints (tumor volume ~1,500 mm³, humane moribund criteria, or scheduled termination), mice are euthanized. Primary tumors are excised, weighed, and photographed. Regional lymph nodes, lungs, liver, and other relevant organs are collected for metastasis assessment.
7. Histopathological and Molecular Analysis: Tumor tissues are fixed in formalin for H&E staining and immunohistochemistry (HER2, Ki-67, cleaved caspase-3, phospho-AKT, phospho-ERK), or snap-frozen for Western blot, qPCR, and RNA-seq analysis. Blood samples may be collected for pharmacokinetic profiling if required by the study design.
8. Data Integration and Reporting: All tumor growth curves, body weight trajectories, histopathology scores, and molecular biomarker data are compiled into a comprehensive study report with statistical analysis. Tumor growth inhibition (TGI) and tumor growth delay (TGD) metrics are calculated to quantify therapeutic efficacy, with full raw data provided for internal validation.

Fig 2. SK-BR-3 Orthotopic Mouse Model construction workflow.

Case Study-SK-BR-3 Orthotopic Mouse Model Development

In a preclinical program focused on HER2-targeted therapy development, the SK-BR-3 orthotopic model was utilized to assess the antitumor activity of a novel biparatopic antibody construct engineered to engage distinct epitopes on the HER2 extracellular domain. Following orthotopic engraftment and randomization, treatment cohorts received escalating doses of the test antibody, a trastuzumab comparator, or vehicle control over a multi-week dosing regimen. Tumor growth monitoring revealed dose-dependent growth suppression in the test antibody groups, with the highest dose cohort exhibiting markedly attenuated tumor volume expansion relative to both vehicle and comparator arms. Histopathological examination of endpoint tumors demonstrated reduced Ki-67 proliferation indices and increased apoptotic signaling in the treated groups, while HER2 receptor occupancy assays confirmed sustained target engagement. These data illustrate the model's capacity to differentiate therapeutic candidates based on mechanism-driven efficacy endpoints and support downstream candidate selection decisions.

Why Choose Alfa Cytology?

Selecting Alfa Cytology as your partner for SK-BR-3 orthotopic breast cancer studies ensures access to a scientifically rigorous, quality-focused CRO platform designed to accelerate preclinical decision-making. Our core differentiators include:

• Validated SK-BR-3 cell banking with documented STR authentication, mycoplasma clearance, and passage-controlled expansion to minimize genetic drift across study cohorts.
• Surgical expertise in mammary fat pad implantation with demonstrated engraftment rates exceeding 90%, ensuring adequate statistical power and reduced animal usage.
• Flexible dosing paradigms supporting intravenous, intraperitoneal, subcutaneous, and oral gavage administration routes, with customizable frequency and cycle designs.
• Integrated histopathology and IHC capabilities featuring validated antibody panels for HER2, Ki-67, phospho-AKT, phospho-ERK, cleaved caspase-3, and CD31 vascular markers.
• Real-time tumor monitoring via digital caliper measurements, with optional imaging upgrades (high-frequency ultrasound or MRI) for non-invasive volumetric assessment.
• Dedicated project management with weekly progress updates, interim data reviews, and collaborative interpretation sessions to align preclinical outcomes with your development strategy.

Contact Us

If your preclinical pipeline demands a HER2-positive breast cancer model that faithfully replicates the in vivo tumor microenvironment, we encourage you to reach out to us to discuss how Alfa Cytology can design and execute a tailored SK-BR-3 orthotopic study aligned with your specific research objectives. From initial protocol consultation through final data delivery, our team is committed to providing actionable insights that de-risk your therapeutic candidates. Contact us today to initiate your project and experience the precision and reliability that define our preclinical oncology services.

For research use only. Not intended for any clinical use.