Breast Cancer Targeting Peptide Binds Keratin 1: A New Molecular Marker for Targeted Drug Delivery to Breast Cancer

Publication year: 2017
Authors: Soudy R. 1,2,5, Etayash H. 1, Bahadorani K.1, Lavasanifar A. 1,3, Kaur K. 1,4
1 - Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
2 - Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2B7, Canada
3 - Department of Chemical and Material Engineering, University of Alberta, Edmonton, Alberta T6G 2V4, Canada
4 - Chapman University School of Pharmacy (CUSP), Harry and Diane Rinker Health Science Campus, Chapman University, Irvine, California 92618-1908, United States
5 - Faculty of Pharmacy, Cairo University, Giza, Egypt
Published in: Molecular Pharmaceutics, 2017, Vol. 14 (3), p. 593–604
doi: 10.1021/acs.molpharmaceut.6b00652

The biomarkers or receptors expressed on cancer cells and the targeting ligands with high binding affinity for biomarkers play a key role in early detection and treatment of breast cancer. The breast cancer targeting peptide p160 (12-mer) and its enzymatically stable analogue 18-4 (10-mer) showed marked potential for breast cancer drug delivery using cell studies and animal models. Herein, we used affinity purification, liquid chromatography–tandem mass spectrometry, and proteomics to identify keratin 1 (KRT1) as the target receptor highly expressed on breast cancer cells for p160 peptide(s). Western blot and immunocytochemistry in MCF-7 breast cancer cells confirmed the identity of KRT1. We demonstrate that the p160 or 18-4 binding to MCF-7 breast cancer cells is dependent on the expression of KRT1, and we confirm peptide-KRT1 binding specificity using SPR experiments (Kd ∼ 1.1 μM and 0.98 μM for p160 and 18-4, respectively). Furthermore, we assessed the ability of peptide 18-4 to improve the cellular uptake and anticancer activity of a pro-apoptotic antimicrobial peptide, microcin J25 (MccJ25), in breast cancer cells. A covalent conjugate of peptide 18-4 with MccJ25 showed preferential cytotoxicity toward breast cancer cells with minimal cytotoxicity against normal HUVEC cells. The conjugate inhibited the growth of MDA-MB-435 MDR multidrug-resistant cells with an IC50comparable to that of nonresistant cells. Conjugation improved selective cellular uptake of MccJ25, and the conjugate triggered cancer cell death by apoptosis. Our findings establish KRT1 as a new marker for breast cancer targeting. Additionally, it pinpoints the potential use of antimicrobial lasso peptides as a novel class of anticancer therapeutics.

MP-SPR keywords: affinity, cancer, fragment protein, peptide binding, protein – peptide interaction, specificity, targeted drug delivery