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Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines
Belén Ramírez-Cordero1, Yanis Toledano, Patricia Cano-Sánchez
1Instituto de Química, Universidad Nacional Autónoma de México , Ciudad Universitaria, Circuito Exterior s/n, México, D.F. 04510, México.
Abstract:
The scorpion toxin tamapin displays the most potent and selective blockage against KCa2.2 channels known to date. In this work, we report the biosynthesis, three-dimensional structure, and cytotoxicity on cancer cell lines (Jurkat E6-1 and human mammary breast cancer MDA-MB-231) of recombinant tamapin and five related peptides bearing mutations on residues (R6A,R7A, R13A, R6A-R7A, and GS-tamapin) that were previously suggested to be important for tamapin's activity. The indicated cell lines were used as they constitutively express KCa2.2 channels. The studied toxin-like peptides displayed lethal responses on Jurkat T cells and breast cancer cells; their effect is dose- and time-dependent with IC50 values in the nanomolar range. The order of potency is r-tamapin>GS-tamapin>R6A>R13A>R6A-R7A>R7A for Jurkat T cells and r-tamapin>R7A for MDA-MB-231 breast cancer cells. Our structural determination by NMR demonstrated that r-tamapin preserves the folding of the αKTx5 subfamily and that neither single nor double alanine mutations affect the three-dimensional structure of the wild-type peptide. In contrast, our activity assays show that changes in cytotoxicity are related to the chemical nature of certain residues. Our results suggest that the toxic activity of r-tamapin on Jurkat and breast cancer cells could be mediated by the interaction of charged residues in tamapin with KCa2.2 channels via the apoptotic cell death pathway.
Insights
Scorpion toxin tamapin and its variants show potent cytotoxicity against Jurkat T cells and breast cancer cells by blocking KCa2.2 channels. Structural analysis reveals mutations do not alter peptide folding but impact activity, suggesting charged residues mediate cell death.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Scorpion toxin tamapin is a potent and selective blocker of KCa2.2 channels.
- KCa2.2 channels are implicated in various cellular functions, including T-cell activation and cancer cell proliferation.
Purpose of the Study:
- To investigate the biosynthesis, structure, and cytotoxicity of recombinant tamapin and its mutants.
- To explore the role of specific residues in tamapin's activity against KCa2.2 channels.
- To assess the therapeutic potential of tamapin and its analogs in cancer treatment.
Main Methods:
- Biosynthesis of recombinant tamapin and five mutant peptides.
- Three-dimensional structure determination using Nuclear Magnetic Resonance (NMR).
- Cytotoxicity assays on Jurkat E6-1 T cells and MDA-MB-231 breast cancer cells.
Main Results:
- Recombinant tamapin and its variants exhibit dose- and time-dependent cytotoxicity with nanomolar IC50 values.
- Tamapin and GS-tamapin show the highest potency against Jurkat T cells, while tamapin is most potent against MDA-MB-231 cells.
- NMR structural analysis confirms that mutations do not disrupt the overall three-dimensional structure of tamapin.
Conclusions:
- Tamapin and its analogs possess significant cytotoxic activity against cancer cell lines, likely mediated by KCa2.2 channel interaction.
- Specific charged residues in tamapin are crucial for its cytotoxic effects, potentially through inducing apoptosis.
- Tamapin and its derivatives represent promising candidates for developing novel cancer therapeutics.
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