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Effect of a C-end rule modification on antitumor activity of thymosin α1
Fanwen Wang1, Caoying Xu1, Renhao Peng1
1School of Life Science and Technology, China Pharmaceutical University, 24 Tongjiaxiang 24, Nanjing, 210009, China.
Abstract:
Thymosin α1 (Tα1), a hormone containing 28 amino acids, has been approved in several cancer therapies, but the lack of tumor-targeting hinders its full use in tumor treatment. We designed a new peptide by connecting Tα1 and RGDR, generating a product, Tα1-RGDR, where RGDR is located in the C-end with both tumor-homing and cell internalizing properties (C-end rule peptides, a consensus R/KXXR/K motif). This work aimed to study the antitumor and immunological activities of Tα1-RGDR, and its differences compared with the wild-type Tα1. The antitumor and immunological activities of Tα1-RGDR were measured using the B16F10 tumor and immunologic suppression models. Tα1-RGDR treatment led to significant inhibition of tumor growth at a dose at which Tα1 showed a slight effect in the B16F10 tumor growth model. In the immunologic suppression model, Tα1-RGDR shared almost equivalent immunomodulatory effect with Tα1. These results demonstrated the better therapeutic effects after treatment with Tα1-RGDR compared with Tα1. Moreover, both Tα1-RGDR and Tα1 shared a helical conformation in the presence of trifluoroethanol based on CD spectroscopy. Our dock information of Tα1-RGDR when combined with integrin αvβ3 or neuropilin-1 further confirmed previous experimental results. All these findings suggest that Tα1-RGDR might be a useful therapy for tumors by overcoming its wild type limitation of tumor homing.
Insights
A novel peptide, thymosin α1-RGDR (Tα1-RGDR), demonstrates enhanced antitumor effects compared to thymosin α1 (Tα1) by improving tumor targeting. This peptide shows significant tumor growth inhibition and retains immunomodulatory activity.
Area of Science:
- Biochemistry
- Immunology
- Oncology
Background:
- Thymosin α1 (Tα1) is an approved cancer therapeutic, but its efficacy is limited by poor tumor targeting.
- Developing targeted delivery systems is crucial for enhancing Tα1's therapeutic potential in cancer treatment.
Purpose of the Study:
- To synthesize and evaluate the antitumor and immunological activities of a novel Tα1-RGDR peptide conjugate.
- To compare the efficacy of Tα1-RGDR with wild-type Tα1 in preclinical cancer models.
Main Methods:
- Peptide synthesis of Tα1-RGDR incorporating the RGDR tumor-homing motif.
- Assessment of antitumor activity using the B16F10 melanoma model.
- Evaluation of immunomodulatory effects in an immunologic suppression model.
- Circular dichroism (CD) spectroscopy to analyze peptide conformation.
- Molecular docking simulations with integrin αvβ3 and neuropilin-1.
Main Results:
- Tα1-RGDR significantly inhibited B16F10 tumor growth at doses where Tα1 had minimal effect.
- Tα1-RGDR exhibited comparable immunomodulatory effects to Tα1 in an immunologic suppression model.
- CD spectroscopy confirmed a similar helical conformation for both Tα1 and Tα1-RGDR.
- Docking studies supported the interaction of Tα1-RGDR with target receptors, including integrin αvβ3 and neuropilin-1.
Conclusions:
- Tα1-RGDR demonstrates superior therapeutic potential over Tα1 due to enhanced tumor targeting.
- The Tα1-RGDR peptide conjugate represents a promising strategy to overcome the limitations of Tα1 in cancer therapy.
- Further investigation into Tα1-RGDR as a novel tumor-targeting therapeutic is warranted.
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