In Silico Exploration and Biological Evaluation of Bispecific Peptides Derived from Anti-HER2 Antibodies and Peptide-Camptothecin Conjugates for HER2-Positive Breast Cancer.

To enhance the affinity of the human epidermal growth receptor 2 (HER2) targeted peptide developed previously, bispecific fusion peptides P1GCGT1 and P1GCGCGT1 were designed using an in silico approach. Molecular dynamic simulation showed that both peptides strongly interacted with HER2 domains II and IV. Compared with peptides targeting each single domain, P1GCGT1 and P1GCGCGT1 could bind to HER2 more significantly and targeted HER2-positive cells specifically. Additionally, both peptides were used to generate peptide-drug conjugates with camptothecin (CPT), among which I-1 and I-4 were screened for enhanced cellular activity and selectivity. Biological evaluation demonstrated that I-1 and I-4 induced cell apoptosis, promoted cell cycle arrestin S-phase, and inhibited Topo I activity. The binding affinity assay and confocal analysis revealed that I-1 and I-4 were effective at targeting HER2. Moreover, I-1 and I-4 showed better stability than single targeting peptide and presented enhanced antitumor activity and safety than CPT in tumor-bearing mice.

Exploration of novel phthalazinone derivatives as potential efflux transporter inhibitors for reversing multidrug resistance and improving the oral absorption of paclitaxel.

Chemotherapy is an important means of cancer treatment. However, overexpression of efflux transporters (including but not limited to P-gp and BCRP) can lead to resistance to cancer chemotherapy. Multiple-target inhibitors of efflux transporter can be overcome the resistance and improve the oral bioavailability of chemotherapy drugs. Therefore, we designed and synthesized a series of phthalazinone ring derivatives (1-20) with different aromatic heterocycles substituents on the amide bond for dual inhibition of P-gp and BCRP. Most target compounds significantly increased the accumulation of P-gp substrates in the chemo-resistant cancer cell lines by inhibiting the efflux of transporters. Compound 19 in particular showed stronger MDR reversal compared to Gefitinib and Verapamil, and comparable to that of the BCRP inhibitor Ko143. In addition, compound 19 improved intestinal absorption of paclitaxel (PTX) and enhanced the bioavailability of the orally administered drug in vivo.

Structure-Based Discovery of Pyrimidine Aminobenzene Derivatives as Potent Oral Reversal Agents against P-gp- and BCRP-Mediated Multidrug Resistance.

Overexpression of ATP binding cassette (ABC) transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), is an important factor leading to multidrug resistance (MDR) in cancer treatments. Three subclasses of dual inhibitors of P-gp and BCRP were designed based on the active moieties of BCRP inhibitors, tyrosine kinase inhibitors, and P-gp inhibitors, of which compound 21 possessed low cytotoxicity, high reversal potency, and good lipid distribution coefficient. 21 also increased the accumulation of Adriamycin (ADM) and Mitoxantrone (MX), blocked Rh123 efflux, and made no change in the protein expression of P-gp and BCRP. Importantly, coadministration of 21 can significantly improve the oral bioavailability of paclitaxel (PTX). It was also demonstrated that 21 significantly inhibited the growth of K562/A02 xenograft tumors by increasing the sensitivity of ADM in vivo. In summary, 21 has the potential to overcome MDR caused by P-gp and BCRP and to improve the oral bioavailability of PTX.