An anti-EGFR/anti- HER2 Bispecific Antibody with Enhanced Antitumor Activity Against Acquired Gefitinib-Resistant NSCLC Cells

Background: Acquired resistance to epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKIs) is a recurrent phenomenon during clinical therapy of non‑small-cell lung cancer (NSCLC). Studies have shown that HER2 is a key factor contributing to drug resistance in a variety of cancers. Furthermore, we have observed that HER2 is overexpressed in PC-9 NSCLC cells with acquired gefitinib-resistance (PC-9/GR) as compared to that in PC-9 cells. Objective: We hypothesized that blocking both EGFR and HER2 may serve as a potential strategy for treatment of NSCLC with acquired gefitinib-resistance. Methods: To target both EGFR and HER2 simultaneously, we developed a bispecific antibody HECrossMAb, which was derived from a humanized Cetuximab and Trastuzumab. The binding affinity of HECrossMAb for EGFR and HER2 was measured using enzyme-linked immunosorbent assay. The MTT assay was used to determine the effect of HECrossMAb on the proliferation of PC‑9 and PC‑9/GR cells in vitro. Finally, the effect of HECrossMAb on PI3K/AKT signaling and associated transcription factors was measured using western blot analysis. Results: Our results showed that HECrossMAb exerts enhanced cytotoxicity in both PC-9 and PC-9/GR cells by inhibiting the activation of PI3K/AKT signaling and expression of relevant transcription factors such as AEG-1, c-Myc, and c-Fos. Conclusion: Our results suggest that HECrossMAb may function as a potential therapeutic agent for the treatment of NSCLC overexpressing EGFR and HER2.

Activation of LncRNA HOTAIR by STAT3 Promotes Gefitinib Resistance and Tumourigenesis by Targeting MicroRNA-216a in NSCLC

Background: Gefitinib resistance has become a major obstacle for cancer therapy of non-small cell lung cancer (NSCLC). Exosome-mediated transfer of long noncoding RNAs (lncRNAs) is associated with the drug-resistance in various tumors. However, the role of NSCLC-specific exosomal lncRNAs remains largely unknown. The aim of this study is to explore the role of exosomal Hox transcript antisense intergenic RNA (HOTAIR) on gefitinib resistance in NSCLC. Methods: We investigated the expression of lncRNAs in 5 paired gefitinib-sensitive and gefitinib-resistant tissues of NSCLC by microarray analysis. The qRT-PCR analysis was to investigate the expression pattern of HOTAIR in gefitinib-resistant NSCLC patient tissues and cell lines. Then, we investigated the effects of HOTAIR on gefitinib resistance in vitro and in vivo. Results: In this study, we found HOTAIR was evidently up-regulated in both tissues and serum exosome of gefitinib-resistant NSCLC patients. Moreover, by knocking down HOTAIR, we found that HOTAIR promoted the proliferation of NSCLC cells in vitro, as well as inhibited cell apoptosis and cell sensitivity to gefitinib. Extracellular HOTAIR could be incorporated into exosomes and transmitted to sensitive cells, thus disseminated gefitinib resistance. The expression level of HOTAIR from circulating exosomes is significantly higher in NSCLC patients with gefitinib resistance than those without gefitinib resistance. Mechanistically, bioinformatic analysis coupled with dual luciferase assay revealed that HOTAIR served as miR-216a sponge, and MAP1S was identified as a functional target of miR-216a. Conclusions: In conclusion, these data suggest that exosomal HOTAIR serves as an oncogenic role in gefitinib resistance of NSCLC cells CRC through activating miR-216a/MAP1S signaling pathway, providing a novel avenue for the treatment of NSCLC.