Cell Internalization in Fluidic Culture Conditions Is Improved When Microparticles Are Specifically Targeted to the Human Epidermal Growth Factor Receptor 2 (HER2).

Inmaculada Mora-Espí,Leonardo Barrios,Jorge Soriano,Carme Nogués,Elena Ibáñez,Thorarinn Gudjonsson

doi:10.3390/pharmaceutics11040177

Inmaculada Mora-Espí, Leonardo Barrios + Show 4 more

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https://doi.org/10.3390/pharmaceutics11040177

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Abstract

Purpose: To determine if the specific targeting of microparticles improves their internalization by cells under fluidic conditions. Methods: Two isogenic breast epithelial cell lines, one overexpressing the Human Epidermal Growth Factor Receptor 2 (HER2) oncogene (D492HER2) and highly tumorigenic and the other expressing HER2 at much lower levels and non-tumorigenic (D492), were cultured in the presence of polystyrene microparticles of 1 µm in diameter, biofunctionalized with either a specific anti-HER2 antibody or a non-specific secondary antibody. Mono- and cocultures of both cell lines in static and fluidic conditions were performed, and the cells with internalized microparticles were scored. Results: Globally, the D492 cell line showed a higher endocytic capacity than the D492HER2 cell line. Microparticles that were functionalized with the anti-HER2 antibody were internalized by a higher percentage of cells than microparticles functionalized with the non-specific secondary antibody. Although internalization was reduced in fluidic culture conditions in comparison with static conditions, the increase in the internalization of microparticles biofunctionalized with the anti-HER2 antibody was higher for the cell line overexpressing HER2. Conclusion: The biofunctionalization of microparticles with a specific targeting molecule remarkably increases their internalization by cells in fluidic culture conditions (simulating the blood stream). This result emphasizes the importance of targeting for future in vivo delivery of drugs and bioactive molecules through microparticles.

Highlights

Drug targeting has the potential to improve the therapeutic efficacy and mitigate the non-specific effects of many drugs
The fixed cells were permeabilized with 0.1% Triton X-100 (Sigma-Aldrich) in phosphate buffer saline (PBS) for 10 min at room temperature (RT), washed with PBS, and blocked with 3% bovine serum albumin (BSA) (Sigma-Aldrich) in PBS for 40 min
To distinguish between D492 and D492HER2 in cocultures, the cells were first incubated with rabbit anti-Human Epidermal Growth Factor Receptor 2 (HER2) monoclonal antibody (1:200, Cell Signaling, Danvers, MA, USA) overnight at 4 ◦C

Summary

Introduction

Drug targeting has the potential to improve the therapeutic efficacy and mitigate the non-specific effects of many drugs. To target cancer cells, NPs and μPs surfaces can be modified to increase the interaction with plasma membrane-specific markers like the transferrin receptor [18], the folate receptor [19], or the human epidermal growth factor receptor 2 (HER2, known as ERBB2) [20,21]. HER2 is a receptor tyrosine kinase which is overexpressed by some types of cancer cells and is considered a marker of poor clinical outcome in breast and ovarian cancer [22,23]. Some treatments directed to this target have already been approved and are clinically used, such as the anti-HER2 monoclonal antibody trastuzumab, alone or in combination with emtansine (T-DM1) [24], and the HER2 tyrosine kinase activity inhibitor lapatinib

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