Chemoresistance Mechanisms in SK-OV-3 Ovarian Cancer Cells
Published: 2023 | Last reviewed: May 2026
SK-OV-3 is one of the most widely used ovarian cancer cell lines in preclinical research, primarily because of its well-characterised intrinsic resistance to platinum-based chemotherapy. Understanding how these cells evade drug-induced death is central to developing combination strategies that can restore sensitivity — making SK-OV-3 an essential model for chemoresistance studies.
Key Characteristics at a Glance
| Feature | SK-OV-3 | Typical Platinum-Sensitive Line (e.g. A2780) |
|---|---|---|
| Cisplatin IC50 | ~5–10× higher than sensitive lines | Low (submicromolar range) |
| p53 status | Null (deleted) | Wild-type or mutant |
| HER2 expression | Amplified | Low / negative |
| Homologous recombination | Intact (HR-proficient) | Variable |
| Drug efflux (ABC transporters) | Elevated MRP2, BCRP expression | Baseline levels |
| Anti-apoptotic signalling | BCL-2/BCL-XL overexpressed; PI3K/AKT constitutively active | Normal apoptotic threshold |
| Primary research use | Chemoresistance mechanisms, combination therapy screening | Drug sensitivity assays, BRCA model studies |
Four Mechanisms Behind SK-OV-3 Platinum Resistance
SK-OV-3 cells resist platinum-based chemotherapy through at least four concurrent pathways — drug efflux, enhanced DNA repair, apoptosis evasion, and pro-survival signalling. Because these mechanisms operate simultaneously, single-agent reversal strategies rarely work in isolation.
Drug efflux
- Key players: P-gp (MDR1/ABCB1), MRP2 (ABCC2), BCRP (ABCG2)
- Effect: Lowers intracellular drug concentration below the cytotoxic threshold
- How to study it: Calcein-AM / rhodamine 123 flow cytometry; atomic absorption spectroscopy
Enhanced DNA repair
- Key players: ERCC1 (NER pathway), intact homologous recombination (HR)
- Effect: Rapid clearance of platinum-DNA adducts prevents lethal damage
- How to study it: γH2AX foci resolution kinetics; Comet assay
Apoptosis evasion
- Key players: p53 null; BCL-2/BCL-XL overexpression; IAP proteins
- Effect: Cells survive genotoxic insult that would kill normal cells
- How to study it: Annexin V/PI flow cytometry; caspase-3/7 activity assays
Pro-survival signalling
- Key players: PI3K/AKT (constitutively active); NF-κB; HER2 amplification
- Effect: Actively suppresses apoptotic signals and promotes cell survival
- How to study it: Phospho-protein western blot; targeted inhibitor sensitivity panels
Molecular Basis of SK-OV-3 Platinum Resistance
SK-OV-3 cells are intrinsically resistant to cisplatin and carboplatin — the backbone of ovarian cancer chemotherapy. This resistance is multifactorial, arising from simultaneous alterations in drug transport, DNA damage response, and cell death signalling. Unlike acquired resistance models, SK-OV-3 offers the advantage of a stable, reproducible resistant phenotype without requiring drug-selection protocols.
SK-OV-3 Cells (300342) show IC50 values for cisplatin approximately 5–10-fold higher than platinum-sensitive ovarian cancer lines. The cells are p53-null, which eliminates a critical mediator of DNA damage-induced apoptosis and makes them insensitive to many DNA-damaging agents that rely on p53 to trigger cell death. This is important context when interpreting any drug response data generated in this line.
For your research: If you need a resistant comparator alongside a sensitive line, pair SK-OV-3 with A2780 (platinum-sensitive, p53 wild-type) to establish a clean resistance/sensitivity axis in your assays.
Drug Efflux and Reduced Intracellular Accumulation
ATP-binding cassette (ABC) transporters actively export chemotherapeutic agents from cells before they can accumulate to cytotoxic levels. SK-OV-3 expresses elevated levels of MRP2 (ABCC2) and BCRP (ABCG2), which can export platinum-glutathione conjugates and a wide range of other substrates. P-glycoprotein (P-gp, MDR1/ABCB1) is also expressed and contributes to resistance against taxanes and anthracyclines used in combination regimens.
Efflux activity is most cleanly quantified using calcein-AM or rhodamine 123 as fluorescent P-gp substrates, read by flow cytometry. For platinum specifically, atomic absorption spectroscopy provides direct measurement of intracellular drug accumulation. First-generation ABC inhibitors such as verapamil and cyclosporine A remain useful tool compounds for mechanistic validation in these cells.
For your research: Efflux inhibition experiments in SK-OV-3 are a practical way to establish the contribution of active transport to the overall resistant phenotype before moving to clinical-stage reversal agents.
Enhanced DNA Damage Repair Capacity
Platinum agents kill cells by forming DNA adducts that block replication and transcription. SK-OV-3 cells counter this through elevated nucleotide excision repair (NER) activity — ERCC1 expression is high, and knockdown experiments consistently sensitise the cells to platinum. Critically, SK-OV-3 retains intact homologous recombination (HR), unlike BRCA-mutant ovarian cancer lines. This HR proficiency enables efficient repair of double-strand breaks and interstrand crosslinks, and it also means PARP inhibitors alone will not induce synthetic lethality here — they need to be combined with a HR-disabling agent.
DNA damage kinetics in SK-OV-3 can be followed using γH2AX immunofluorescence or flow cytometry: rapid foci resolution after platinum exposure is a hallmark of the resistant phenotype. The Comet assay provides orthogonal single-cell confirmation of repair efficiency.
For your research: SK-OV-3's HR-proficient status makes it an ideal negative control when validating PARP inhibitor activity, and a useful model for studying NER-targeted sensitisation strategies.
Apoptosis Evasion and Pro-Survival Signalling
Even when DNA damage accumulates beyond the cell's repair capacity, SK-OV-3 has multiple brakes on the apoptotic machinery. BCL-2 and BCL-XL are overexpressed, tilting the balance of BCL-2 family proteins strongly anti-apoptotic and preventing mitochondrial outer membrane permeabilisation (MOMP). Without MOMP, cytochrome c is not released and the caspase cascade does not activate — cells survive damage that would be lethal in a normal context.
Constitutively active PI3K/AKT signalling reinforces this block: AKT phosphorylates and inactivates pro-apoptotic proteins including BAD and FOXO transcription factors, keeping survival signals switched on regardless of external damage signals. HER2 amplification in SK-OV-3 drives both PI3K/AKT and MAPK pathway activity, which is why HER2-targeted agents (trastuzumab, lapatinib) show synergy with chemotherapy in this model.
BH3 mimetics such as venetoclax and navitoclax directly antagonise BCL-2/BCL-XL and have demonstrated synergy with platinum agents in SK-OV-3, as does PI3K/AKT pathway inhibition. Combination index analysis using a matrix of platinum dose + pathway inhibitor dose is the standard approach for quantifying synergy in this model.
For your research: The convergence of HER2 amplification and defective apoptosis makes SK-OV-3 one of the few ovarian cancer lines where HER2-targeted, BCL-2-targeted, and chemotherapy combinations can all be meaningfully tested in a single model.
Order SK-OV-3 Cells from Cytion
Cytion's SK-OV-3 cells (product code 300342) are STR-authenticated, mycoplasma-tested, and supplied as cryopreserved vials with a certificate of analysis. Each lot is quality-controlled prior to dispatch to ensure consistent growth characteristics and the expected platinum-resistant phenotype.
- Authentication: STR profiling against ATCC reference profile
- Biosafety: Mycoplasma-negative, tested by PCR
- Format: Cryopreserved in DMSO-based freeze medium, ≥1×10⁶ viable cells per vial