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B-Raf inhibition in conjunctival melanoma cell lines with PLX 4720
Aline I Riechardt1, Anna-Karina B Maier1, Anika Nonnenmacher2
1Augenklinik, Charité-Universitätsmedizin Berlin, Berlin, Germany Experimentelle Ophthalmologie, Charité Universitätsmedizin Berlin, Berlin, Germany.
Purpose:
Mutations in the gene coding for the kinase B-Raf are associated with tumour growth in conjunctival melanoma. The purpose of this study is to explore effects of pharmacological B-Raf inhibition in conjunctival melanoma cell lines.
Methods:
The B-Raf genotypes were assessed by PCR and subsequent sequencing. Cytotoxicity, cell viability, proliferation, apoptosis rate and phosphorylation rate of ERK and Akt were analysed in three different conjunctival melanoma cell lines under the influence of the B-Raf inhibitor PLX 4720 at various concentrations.
Results:
The cell lines CRMM-1 and CM2005.1 showed the B-Raf V600E mutation, whereas CRMM-2 expressed a B-Raf wild type. CM2005.1 was highly sensitive to PLX 4720, showing a complete cytotoxic effect for >1 µM, as well as a significant concentration-dependent reduction of the proliferation rate and viability rate. Even though CRMM-1 also carries the B-Raf V600E mutation, it did not react as sensitive to PLX 4720 inhibition as CM2005.1, but showed a significant concentration-dependent reduction regarding proliferation and viability. PLX 4720 had only slight impact on CRMM-2 in high concentrations (10 µM) regarding cytotoxicity, proliferation and viability. Fluorescence-activated cell sorting analysis revealed that PLX 4720 acted predominantly antiproliferative and not via an induction of apoptosis. The phosphorylation rate of ERK was significantly reduced in CRMM-1 and CM2005.1, while it remained unchanged in CRMM-2. The phosphorylation rate of Akt was significantly elevated in CRMM-2.
Conclusions:
Proliferation inhibition of conjunctival melanoma cells by PLX 4720 depends on their B-Raf genotype. Therefore, therapeutic application of B-Raf inhibitors should take into account the specific B-Raf genotype.
Insights
Pharmacological B-Raf inhibition using PLX 4720 effectively reduces conjunctival melanoma cell proliferation, but its efficacy depends on the specific B-Raf genotype. This highlights the importance of genotype-guided therapeutic strategies for conjunctival melanoma treatment.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Mutations in the B-Raf gene are implicated in conjunctival melanoma development.
- Targeting B-Raf kinase offers a potential therapeutic strategy for this rare cancer.
Purpose of the Study:
- To investigate the effects of pharmacological B-Raf inhibition on conjunctival melanoma cell lines.
- To determine the role of B-Raf genotype in cellular response to B-Raf inhibitors.
Main Methods:
- B-Raf genotyping using PCR and sequencing.
- Assessing cytotoxicity, viability, proliferation, and apoptosis rates in response to PLX 4720.
- Analyzing ERK and Akt phosphorylation levels.
Main Results:
- The B-Raf V600E mutation was present in sensitive cell lines (CM2005.1, CRMM-1).
- PLX 4720 demonstrated significant anti-proliferative and cytotoxic effects in B-Raf V600E mutated cell lines, with varying sensitivity.
- Wild-type B-Raf cell lines showed minimal response to PLX 4720, with increased Akt phosphorylation observed.
Conclusions:
- The anti-proliferative effect of PLX 4720 on conjunctival melanoma cells is dependent on the B-Raf genotype.
- Therapeutic strategies involving B-Raf inhibitors should consider the patient's specific B-Raf mutational status.
