Study summary · research use only
Chondroitin sulfate as a molecular portal that preferentially mediates the apoptotic killing of tumor cells by penetratin-directed mitochondria-disrupting peptides
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this study comparing tumor versus normal cell lines, the authors examined chondroitin sulfate as a mediator of tumor-preferential killing by penetratin (Antp)-directed mitochondria-disrupting peptides. Using PNC27 as a model, they constructed three peptides (PT, PR9, PD3) replacing Antp with other cell-penetrating peptides. The abstract reports IC50 values of PNC27 in tumor cells were 2-3 times lower than in normal cells, whereas the three engineered peptides showed similar cytotoxic effects in tumor and normal cells. Three chimeric Antp peptides with mitochondria-disrupting sequences preferentially induced tumor cell apoptosis, with IC50 values (3-10 microM) 3-6 times lower in tumor than normal cells, while TAT-directed peptides were cytotoxic to both. Antp-directed peptides bound chondroitin sulfate, and removing endogenous chondroitin sulfate reduced their tumor cytotoxicity.
Abstract
The use of cell-penetrating peptides (CPPs) as drug carriers for targeted therapy is limited by the unrestricted cellular translocation of CPPs. The preferential induction of tumor cell death by penetratin (Antp)-directed peptides (PNC27 and PNC28), however, suggests that the CPP Antp may contribute to the preferential cytotoxicity of these peptides. Using PNC27 as a molecular model, we constructed three novel peptides (PT, PR9, and PD3) by replacing the leader peptide Antp with one of three distinct CPPs (TAT, R9, or DPV3), respectively. The IC(50) values of PNC27 in tumor cells were 2-3 times lower than in normal cells. However, all three engineered peptides demonstrated similar cytotoxic effects in tumor and normal cells. Another three chimeric peptides containing the leader peptide Antp with different mitochondria-disrupting peptides (KLA-Antp (KGA), B27-Antp (BA27), and B28-Antp (BA28)), preferentially induced apoptosis in tumor cells. The IC(50) values of these peptides (3-10 microM) were 3-6 times lower in tumor cells than in normal cells. In contrast, TAT-directed peptides (TAT-KLA (TK), TAT-B27 (TB27), and TAT-B28 (TB28)), were cytotoxic to both tumor and normal cells. These data demonstrate that the leader peptide Antp contributes to the preferential cytotoxicity of Antp-directed peptides. Furthermore, Antp-directed peptides bind chondroitin sulfate (CS), and the removal of endogenous CS reduces the cytotoxic effects of Antp-directed peptides in tumor cells. The overexpression of CS in tumor cells is positively correlated to the cell entry and cytotoxicity of Antp- directed peptides. These results suggest that CS overexpression in tumor cells is an important molecular portal that mediates the preferential cytotoxicity of Antp-directed peptides.
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