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Protease-activated Affibody molecules for increasing the therapeutic window in cancer therapy
KTH, School of Biotechnology (BIO).
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Proteasaktiverade Affibodymolekyler för minskade biverkningar i cancerterapi (Swedish)
Abstract [en]

Biomarkers in cancer are present in both disease and normal tissue, which narrows the therapeutic window in order to avoid severe side effects. In this project, the concept of using protease activated affibody molecules to target the biomarker Human Epidermal Growth Factor Receptor 2 /HER2), was studied. HER2 is over expressed in certain types of breast cancer.

Tumors have an up regulation in expression of specific proteases in their immediate surroundings. These proteases are quite specific to different tumors, making them ideal to activate prodrugs at the site of the tumor. This allows for a muck more specific targeting of the biomarkers present in disease tissue and thus increases the therapeutic window. One of the causes of breast cancer is through an over expression of HER2, which is responsible for 15.20% of all cases. This type of tumors produces certain types of proteases that are active in the area surrounding the tumor. One of these proteases is matrix mealloprotease 1 (MMP1).

By linking two affibodies together, one that targets HER2 (ZHER2:342) and one antiidiotypic for the HER2-binding affiboday (ZE01), they will interact with each other and binding to HER2 can be blocked. By inserting a protease cleavage site into the linker, the dimer can be activated at the tumor site through cleavage, which releases the HER2-binding affibody and allows it to bind to its target and prevent dimerization. The protease cleavage site is a MMP1 stie with the amino acid sequence GPQAIAGQ.

The constructs were cloned and analyzed using staphylococcal cell display and flow sytometry. It was shown that ZE01 effectively blocked binding of ZHER2:342 to HER2. Analysis of the constructs showed that incubation with MMP1 successfully cleaved the linker and allowed ZHER2:342 to bind HER2.

The method is very promising, and can be used to specifically target other biomarkers as well in the future. Especially interesting targets are the biomarkers that are quite unspecific for a disease. This usually associates them with more severe side effects and less effective tretments.

Place, publisher, year, edition, pages
Keyword [en]
Targeted cancer therapy, side effects, protease, Affibody molecules, bacterial display
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-150699OAI: diva2:744736
Available from: 2015-04-17 Created: 2014-09-08 Last updated: 2015-09-23Bibliographically approved

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