SK-MEL-28 / SK-MEL-28-luc Orthotopic Mouse Model Service for Melanoma

The SK-MEL-28 / SK-MEL-28-luc orthotopic mouse model of melanoma implants a lightly pigmented, NCI-60-panel human melanoma with BRAF V600E into its cutaneous site of origin, where tumors grow in organ-authentic skin conditions and their expansion and spread are followed non-invasively by luciferase bioluminescence. Alfa Cytology delivers this platform as an integrated preclinical service: authenticated HTB-72 banking, luciferase line qualification, intradermal or flank engraftment in nude or SCID recipients, scheduled whole-body and ex vivo imaging, BRAF-pathway and pigmentation-aware dosing, and endpoints spanning tumor metrics, metastatic survey, molecular profiling, and histopathology.

Overview of SK-MEL-28 / SK-MEL-28-luc Orthotopic Mouse Model for Melanoma

SK-MEL-28 belongs to the celebrated series of melanoma lines established at Memorial Sloan Kettering by Toshitada Takahashi and Lloyd Old, derived in 1975 from the skin of a 51-year-old male patient with malignant melanoma and deposited with ATCC as HTB-72. The cells are polygonal and adherent, lightly pigmented, and carry a hypotetraploid karyotype of remarkable complexity — modal chromosome number 90 with more than eighteen marker chromosomes, including a signature Y-to-autosome translocation, der(20)t(Y;20)(q11.23;q13.3). Genetically it pairs the BRAF V600E mutation with wild-type NRAS, but its cell-cycle wiring differs from that of its famous cousin A375: instead of losing p16, SK-MEL-28 bypasses the p16 pathway through a CDK4 Arg24Cys mutation, and it carries a TP53 Leu145Arg substitution — yielding high phospho-ERK together with high phospho-AKT, a dual-pathway-active state that influences drug response logic. As a member of the NCI-60 panel it has been profiled at scale, with documented HLA type (A11, A26, B40, DRw4) and isozyme markers, and it forms malignant melanomas of the large-round-cell type in nude mice.

Fig 1. SK-MEL-28 xenograft efficacy study showing that oral LJ-1-60 at 20 and 40 mg/kg for 17 days significantly reduced SK-MEL-28 tumor volume (≈500 vs ≈1,100 mm³ at day 17) and tumor weight compared with vehicle, with normal body weight maintenance, macroscopic excised tumors and reduced Ki-67 positive rate by IHC confirming antiproliferative activity in the SK-MEL-28 model. (Tang, Ling, et al., 2020)

Orthotopically, SK-MEL-28 helped pioneer the ear-intradermal melanoma model: GFP-tagged cells injected intradermally into the ears of NOD-SCID mice could be followed by intravital imaging at single-cell resolution from 24 hours onward — before any tumor was palpable — with intravasated tumor cells visible in vessels by two weeks and GFP-positive deposits detectable in lung and brain at necropsy. Luciferase tagging upgrades this paradigm to quantitative whole-animal bioluminescence: SK-MEL-28-luc cells tracked after D-luciferin administration report primary tumor kinetics and emergent metastatic burden across skin, node, lung, and brain, complementing fluorescence readouts where sub-cellular spatial context is wanted. Pharmacologically, the line has served BRAF-pathway studies of RAF-dependence attenuation by PTEN/RB1 loss, chemopreventive-flavonoid evaluation, and the broader NCI-60 screening heritage — making the SK-MEL-28-luc orthotopic platform a distinctive complement to A375 for programs seeking a pigmented, CDK4-mutant, p53-mutant melanoma context.

Cell Line Information: SK-MEL-28 / SK-MEL-28-luc

SK-MEL-28 is a heavily documented NCI-60 human melanoma line whose pigmentation and dual-pathway activation distinguish it within the BRAF-mutant panel. Its luciferase derivative supports imaging-guided orthotopic studies. Core attributes follow.

Our Services

SK-MEL-28’s quirks — light pigmentation, CDK4 mutation, dual-pathway activation — are exactly the properties programs select it for, and Alfa Cytology treats them as release criteria rather than footnotes. Stocks are expanded from authenticated HTB-72 vials with documented STR identity, passages are capped, and SK-MEL-28-luc lots enter studies only after uniform in vitro luminescence is confirmed. Engraftment follows written intradermal or flank technique with imaging-verified randomization, and endpoint panels are configured to the model’s strengths: BRAF-pathway pharmacodynamics, pigmentation status, and metastatic survey across skin, nodes, lung, and brain. From baseline scan to final slide, Alfa Cytology runs the SK-MEL-28 / SK-MEL-28-luc orthotopic workflow as one continuous, accountable program.

Workflow of SK-MEL-28 / SK-MEL-28-luc Orthotopic Mouse Model Construction

The SK-MEL-28-luc orthotopic workflow pairs cutaneous implantation with imaging-native progression tracking and pathway-aware endpoints. The sequence below is the standard construction-to-analysis flow.

1. Authentication and reporter release: SK-MEL-28 / SK-MEL-28-luc stocks are expanded from authenticated master banks at capped passage, mycoplasma-tested, STR-verified, and released only after uniform firefly luciferase expression (and GFP signal where applicable) is confirmed in vitro.
2. Inoculum preparation: Log-phase adherent cultures are released with 0.25% trypsin-0.53 mM EDTA, washed, counted, and resuspended in sterile PBS at the study dose (5×10⁵ cells in 20-50 µL for ear or dorsal intradermal designs; 1×10⁶ to 5×10⁶ cells for flank cohorts).
3. Recipient preparation: Nude or NOD-SCID mice are acclimatized, body-weight stratified, and anesthetized with ketamine/xylazine or isoflurane per protocol, with the implantation site shaved and disinfected.
4. Orthotopic intradermal implantation: The suspension is injected intradermally into the ear or dorsal skin using a fine needle, creating a visible bleb; flank cohorts are implanted in parallel where designed.
5. Baseline imaging and randomized allocation: Baseline bioluminescence after D-luciferin (150 mg/kg) documents engraftment; cohorts are randomized with matched photon flux and dosing begins — BRAF/MEK-pathway agents, combination regimens, or experimental compounds.
6. Longitudinal monitoring: On a fixed schedule, in vivo whole-body imaging tracks primary tumor signal with caliper measurements in parallel; body weight and clinical condition are scored throughout, and sites of emergent signal are flagged for metastatic follow-up.
7. Endpoint analysis and profiling: At termination, primary tumors and lymph nodes are excised and weighed, skin, lungs, brain, and liver are imaged ex vivo and inspected, histopathology confirms melanoma with pigmentation status, and molecular profiling (phospho-ERK/phospho-AKT, pathway markers) is performed on recovered tumor tissue.

Fig 2. SK-MEL-28 / SK-MEL-28-luc orthotopic mouse model construction workflow.

Case Study-SK-MEL-28 / SK-MEL-28-luc Orthotopic Mouse Model Development

Alfa Cytology has implemented the SK-MEL-28 orthotopic platform in preclinical programs spanning BRAF-pathway agents, combination regimens, and pigmentation-targeted or delivery-focused modalities. In these studies, serial bioluminescence tracked primary tumor kinetics alongside emerging signals at nodal and visceral sites, randomized arms started from matched photon flux, and terminal analyses combined tumor and node weights with ex vivo organ imaging and histopathological confirmation including pigmentation status. Where programs required it, recovered tumor tissue was profiled for phospho-ERK and phospho-AKT to contextualize response within the model’s dual-pathway biology. Study-specific designs and results are retained as sponsor-confidential deliverables, and representative outlines can be furnished upon request.

Why Choose Alfa Cytology?

SK-MEL-28 rewards sponsors who value its differences — and those differences demand deliberate execution. Alfa Cytology’s service is built to keep the model’s distinctive biology intact and measurable. Sponsors benefit from:

• Authenticated HTB-72 stocks with STR-documented identity and capped passage before animal use.
• Reporter lines qualified for uniform luciferase (and GFP) expression before release into studies.
• Written intradermal orthotopic technique in ear or dorsal skin, aligned with the published ear-model paradigm.
• Imaging-native progression readouts covering primary site, nodes, lung, and brain.
• Pathway-aware endpoint panels resolving the model’s dual phospho-ERK/phospho-AKT biology.
• Pigmentation-status documentation through histopathology for melanocyte-biology programs.
• Single-point study accountability with per-timepoint reporting from implantation through final analysis.

Contact Us

Seeking a pigmented, dual-pathway-active human melanoma context for your program? Contact us to discuss engraftment route, imaging cadence, and endpoint design for the SK-MEL-28 / SK-MEL-28-luc orthotopic platform. You can also reach out to Alfa Cytology for a customized proposal and quotation — our team will respond with a study design aligned to your therapeutic strategy.

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