The Role of Contactin 1 on Acquired Resistance to Pegylated Arginase in Small Cell Lung Cancer

Abstract

Background: Small cell lung cancer (SCLC) accounts for about 15% of all lung cancer cases. SCLC is characterized by easy to relapse, and current treatment lacks tumor specificity. Arginine is an important amino acid in human, but some tumors lose the ability to synthesize it. So arginine deprivation has become a targeted therapy in certain tumors. BCT-100 is a pegylated arginase with anticancer activity in arginine auxotrophic tumors, such as human melanoma, hepatocellular carcinoma and acute myeloid leukemia. Contactin 1 (CNTN1) is a cell adhesion molecule which plays an important role in drug resistance. The aim of this study is to determine the effects of CNTN1 on BCT-100 acquired resistance in SCLC. Methods: BCT-100 resistant (BR) cells, H446-BR and H526-BR cells, were developed by incubating with serially increasing concentration of BCT-100 with parental H446 (adherent cell line) and H526 (suspension cell line) cells respectively. Gene chip assay was employed to fish out the potential targeted biomarkers in BR cell lines. MTT assay was used to detect cell viability on BR cell lines. Western blotting was employed to evaluate the protein expression. Knockdown of CNTN1 was performed using specific shRNA. Wound healing assay was used to evaluate the cell migration ability in H446 and H446-BR adherent cell lines. Flow cytometry was applied to detect the related biomarkers in BR cells. Results: The protein expression of CNTN1 in H446-BR and H526-BR cells was 2.7 folds and 5.3 folds higher than that in parental cells respectively. Cell migration ability in BR cells was stronger than parental cells: wound healing rate was greatly increased from 48.5% to 69.9% in H446-BR cells. Epithelial-mesenchymal transition (EMT) progression and AKT activation were observed in both BR cell lines. Knockdown of CNTN1 re-sensitized BR cells to BCT-100 treatment and reversed the EMT progression via inhibiting AKT pathway. Conclusion: Contactin 1 modulates BCT-100 resistance through induction of EMT by activating AKT pathway in SCLC.