Rational Design of Novel Antibody Decorated Nanoparticles Targeting Breast Cancer Cells
Date
2023-06-15
Authors
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Journal ISSN
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Publisher
Saudi Digital Library
Abstract
Every year there are over 50,000 new cases of breast cancer in UK, which
represents the most common UK cancer (CR-UK). Despite significant advances
in anti-breast cancer treatments, there is still a need for improved therapeutics to
overcome drug resistance. HER2 (Human Epidermal Growth Factor Receptor 2)
is a transmembrane oncoprotein encoded by the HER2/neu gene and
overexpressed in approximately 20 to 30% of invasive breast cancers. Tumours
overexpressing HER2 are more aggressive and carry a poor prognosis; thus, the
receptor is a priority therapeutic target. One targeting entity is Trastuzumab (Tz),
a monoclonal antibody recognized as one of the most effective agents against
HER2+ breast cancer and has also been attached to chemotherapeutics to form
antibody-drug conjugate (ADC). These ADCs, such as Kadcyla®, require cell
binding to HER2 and access to the cell interior by endocytosis to release the
payload. HER2 is, however, commonly termed the "endocytosis deficient'
member of the HER family of receptors, thus challenging attempts to design
ADCs that need access to lysosomes for drug release and activity.
Previous studies in the laboratory showed that HER2 endocytosis was
significantly promoted with concomitant lysosomal delivery and degradation via
Tz-mediated crosslinking, and this presented work lies under the hypothesis that
nanoparticles (NPs) decorated with sufficient numbers of Tz could also cause
HER2 cross-linking, endocytosis, and HER2 degradation. Later data showed that
HER2 crosslinking induced a form of endocytosis termed macropinocytosis to
drive cell entry. The work presented initially investigated macropinocytosis as a
process in different cell types and ways to inhibit this process using inhibitors
targeting the sodium proton exchanger (NHE1) as a regulator of intracellular pH
and this endocytic process. EIPA (5-(N-Ethyl-N-isopropyl) amiloride) as a
macropinocytosis inhibitor, surprisingly significantly increased the internalisation
of HER2; a result not observed with other NHE1 inhibitors amiloride and the more
selective NHE1 inhibitor cariporide. EIPA was also shown to increase the uptake
of the fluid phase and macropinocytosis marker dextran but had no effect on
endocytosis of transferrin via clathrin-coated vesicles. The results suggest that
EIPA targets need further analysis as modulators of HER2 internalisation and
targets for breast cancer therapy.
Fluorescently labelled Tz- decorated Poly (lactic glycolic acid) NPs were then
generated and found to be highly selective for HER2 expressing breast cancer
cells over controls. Upon incubation with cells, the decorated NPs rapidly
accumulated on the cell surface and also appeared as large intracellular
structures suggestive of macropinosomes. Rhodamine and Doxorubicin
encapsulated Tz-PLGA NPs were synthesised, showing their capacity to drive
internalisation of the fluorophore and cytotoxic drug into vesicular structures, with
the later formulation enhancing the cytotoxicity of the drug over its soluble
counterpart.
Description
The data shows NP-Tz specifically targeting DOX to BC cells enhances its cell toxicity compared to administering it as a free drug. The generated targeting NPs also represent a promising new method for delivering therapies of the future such as siRNA and mRNA. As the field of NPs develops rapidly, new research is regularly published in the cancer and BC space with the hope that this work highlights how detailed cell analysis of NP cell dynamics is needed to give mechanistic information informing future NP design.
Keywords
Rational Design of Novel Antibody Decorated Nanoparticles Targeting Breast Cancer Cells