Theranostics 2019; 9(7):1993-2002. doi:10.7150/thno.31943

Research Paper

DNAzyme Catalyzed Tyramide Depositing Reaction for In Situ Imaging of Protein Status on the Cell Surface

Lulu Xu1,2*, Shengchun Liu3*, Tiantian Yang1, Yifan Shen1, Yuhong Zhang1, Lizhen Huang1, Lutan Zhang1, Shijia Ding4, Fangzhou Song2✉, Wei Cheng1✉

1. The Center for Clinical Molecular Medical Detection, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P. R. China
2. Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, P. R. China
3. Department of Endocrine and Breast Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P. R. China
4. Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, P. R. China
*These authors contributed equally to this work.

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Citation:
Xu L, Liu S, Yang T, Shen Y, Zhang Y, Huang L, Zhang L, Ding S, Song F, Cheng W. DNAzyme Catalyzed Tyramide Depositing Reaction for In Situ Imaging of Protein Status on the Cell Surface. Theranostics 2019; 9(7):1993-2002. doi:10.7150/thno.31943. Available from https://www.thno.org/v09p1993.htm

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Abstract

Effective characterization of protein biomarkers status on the cell surface has important value in the diagnosis and treatment of diseases. Traditional immunohistochemistry can only assess the protein expression level rather than accurately reflect their interaction and oligomerization, resulting in inevitable problems for personalized therapy.

Methods: Herein, we developed a novel DNAzyme-catalyzed tyramide depositing reaction (DCTDR) for in situ amplified imaging of membrane protein status. By using human epidermal growth factor receptor 2 (HER2) as model, the binding of HER2 proteins with specific aptamers induced the formation of activated hemin/G-quadruplex (G4) DNAzyme on the cell surface to catalyze the covalent deposition of fluorescent tyramide on the membrane proteins for fluorescence imaging.

Results: The DCTDR-based imaging can conveniently characterize total HER2 expression and HER2 dimerization on the breast cancer cell surface with the application of aptamer-G4 probes and proximity aptamer-split G4 probes, respectively. The designed DCTDR strategy was successfully applied to quantitatively estimate total HER2 expression and HER2 homodimer on clinical breast cancer tissue sections with high specificity and accuracy.

Conclusion: The DCTDR strategy provides a simple, pragmatic and enzyme-free toolbox to conveniently and sensitively analyze protein status in clinical samples for improving clinical research, cancer diagnostics and personalized treatment.

Keywords: aptamer, hemin/G-quadruplex DNAzyme, tyramide depositing reaction, human epidermal growth factor receptor 2, protein homodimer