Increase in Toxicity of Anticancer Drugs by PMTPV, a Claudin-1-Binding Peptide, Mediated via Down-Regulation of Claudin-1 in Human Lung Adenocarcinoma A549 Cells.

Haruka Nasako,Satoshi Endo,Akira Ikari,Toshiyuki Matsunaga,Yui Takashina,Hiroaki Eguchi,Yoshinobu Ishikawa,Ayaka Ito

doi:10.3390/ijms21165909

Haruka Nasako, Satoshi Endo + Show 6 more

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https://doi.org/10.3390/ijms21165909

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Abstract

Claudin-1 (CLDN1), a tight junctional protein, is highly expressed in lung cancer cells and may contribute to chemoresistance. A drug which decreases CLDN1 expression could be a chemosensitizer for enhancing the efficacy of anticancer drugs, but there is no such drug known. We found that PMTPV, a short peptide, which mimics the structure of second extracellular loop (ECL2) of CLDN1, can reduce the protein level of CLDN1 without affecting the mRNA level in A549 cells derived from human lung adenocarcinoma. The PMTPV-induced decrease in CLDN1 expression was inhibited by monodansylcadaverine, a clathrin-mediated endocytosis inhibitor, and chloroquine, a lysosome inhibitor. Quartz crystal microbalance assay showed that PMTPV can directly bind to the ECL2 of CLDN1. In transwell assay, PMTPV increased fluxes of Lucifer yellow (LY), a paracellular flux marker, and doxorubicin (DXR), an anthracycline anticancer drug, without affecting transepithelial electrical resistance. In three-dimensional spheroid culture, the size and cell viability were unchanged by short peptides, but the fluorescence intensity of hypoxia probe LOX-1 was decreased by PMTPV. PMTPV elevated the accumulation and cytotoxicity of DXR in the spheroids. Similar results were observed by knockdown of CLDN1. Furthermore, the sensitivities to cisplatin (CDDP), docetaxel, and gefitinib were enhanced by PMTPV. The level of CLDN1 expression in CDDP-resistant cells was higher than that in parental A549 cells, which was reduced by PMTPV. PMTPV restored the toxicity to DXR in the CDDP-resistant cells. Our data suggest that PMTPV may become a novel chemosensitizer for lung adenocarcinoma.

Highlights

Non-small cell lung cancer (NSCLC) accounts for 80% of all lung cancer cases and is commonly insensitive and intrinsically resistant to original chemotherapy [1]
We reported that the expression level of CLDN1 is increased by the acquisition of chemoresistance to CDDP in lung adenocarcinoma A549 cells [13]
The mRNA level of CLDN1 was significantly increased in human lung adenocarcinoma and squamous cell carcinoma tissues compared to normal tissues, and has a tendency to increase in large cell and small cell tissues (Figure 1A)

Summary

Introduction

Non-small cell lung cancer (NSCLC) accounts for 80% of all lung cancer cases and is commonly insensitive and intrinsically resistant to original chemotherapy [1]. The patients show the response rate to chemotherapy is about 50% in first-line treatments, but the patients acquire resistance to chemotherapy and the efficacy drops to about 15% in second- or third-line treatments [2,3]. Other traditional chemotherapeutic agents such as gemcitabine, etoposide, and doxorubicin are often used as combination therapy, but they induce chemoresistance. These drugs can acquire cross-resistance to a wide variety of anticancer agents which have no obvious structural or functional similarities [4]. Resistance remains an obstacle in chemotherapy and seriously influences the survival rate of NSCLC patients

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