Part:BBa_K1781002

ZHER2 - affibody with affinity to cytoplasmic domain of HER2

ZHER2 was one of the first affibodies created and it binds to the Human Epidermal Growth Factor 2 (HER2). They originate from mutations in the Immunoglobin G Binding Domain of Protein A from Staphylococcus aureus. Affibodies are engineered to bind to larger proteins or peptides where they imitate monoclonal antibodies. They are used in a multitude of therapies in biotechnology to bioimaging. ZHER2 can particular be used as a protein-protein interaction tool, as well as a way to verify antibody interactions as it binds to the cytoplasmic domain of HER2 at a different epitope than the antibodies.

Improvement and New Application for ZHER2

Group: iGEM2021_Greatbay_SCIE
Author: iGEM2021_Greatbay_SCIE
link: Greatbay_SCIE

The human epidermal growth factor receptor 2 (HER2) is specifically overexpressed in tumors of several cancers, including an aggressive form of breast cancer. It is therefore a target for both cancer diagnostics and therapy. The 58 amino acid residue Zher2 affibody molecule was previously engineered as a high-affinity binder of HER2. ZHER2 binds to a conformational epitope on HER2 that is distant from those recognized by the therapeutic antibodies trastuzumab and pertuzumab. Its small size and lack of interference may provide Zher2 with advantages for diagnostic use or even for delivery of therapeutic agents to HER2-expressing tumors when trastuzumab or pertuzumab are already employed. Biophysical characterization shows that Zher2 is thermodynamically stable in the folded state yet undergoing conformational interconversion on a submillisecond time scale. Our team will provide some improvements and new applications to the parts page with the help of papers.

Better radiotherapy—Specific delivery of ZHER2 affibody-conjugated gold nanoparticles to HER2-positive malignant cells.

Fig.1^[1]An overview of ZHER2 affibody-conjugated gold nanoparticles.

This picture gives us a new enhancement of X-ray radiotherapy by specific delivery of ZHER2 affibody-conjugated gold nanoparticles to HER2-positive malignant cells. The most significant results shows the induced radiosensitizing effect of cysteamine-coated GNPs on four different malignant cell lines exposed to X-ray radiation of megavoltage energy. Induced cytotoxicity of trastuzumab-coated GNPs in combination with X-ray radiation against HER2-positive breast cancerous cells has also been shown.

Better drug delivery—Hyperthermia-triggered intracellular delivery of an anticancer agent to HER2+ cells by HER2-specific affibody (ZHER2-GS-Cys)-conjugated thermosensitive liposomes (HER2+ affisomes).

Fig.2^[2]HER2+ affisomes encompass both targeting and triggering potential.

As show in the picture above, HER2+ affisomes combines the thermosensitive liposome with a HER2- specific affibody-based targeting agent to. In this system, thermosensitive liposomes are based on the lipid destabilizing mechanism, phase-transition effects, and thermal melting temperatures. When locally raise the temperature a few degrees above the human body temperature, the liposome-entrapped drugs could release rapidly and efficiently. Another significant point is the modified HER2-specific affibody molecule which includes a glycine–serine linker between the main affibody segment and its C-terminus cysteine (“ZHER2-GS-Cys”). This modification gets more efficiently when targeting breast cancer cells and ZHER2-GS-Cys retains its ability to conjugate to the liposomes. HER2+ affisomes encompass both targeting and triggering potential. Therefore, it may serve as possible candidates for targeted-triggered delivery of anticancer agents to combat HER2+ breast cancer.

Reference：

1. Pourshohod, A., Jamalan, M., Zeinali, M., Ghanemi, M., & Kheirollah, A. (2019). Enhancement of X-ray radiotherapy by specific delivery of ZHER2 affibody-conjugated gold nanoparticles to HER2-positive malignant cells. Journal of Drug Delivery Science and Technology, 52, 934–941. https://doi.org/10.1016/j.jddst.2019.05.039
2. Smith, B., Lyakhov, I., Loomis, K., Needle, D., Baxa, U., Yavlovich, A., Capala, J., Blumenthal, R., & Puri, A. (2011). Hyperthermia-triggered intracellular delivery of an anticancer agent to HER2+ cells by HER2-specific affibody (ZHER2-GS-Cys)-conjugated thermosensitive liposomes (HER2+ affisomes). Journal of Controlled Release, 153(2), 187–194. https://doi.org/10.1016/j.jconrel.2011.04.005

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 4
  Illegal AgeI site found at 220
  
• 1000
  COMPATIBLE WITH RFC[1000]