Establishment of drug-resistant cell lines in non-small cell lung cancer

Non-small cell lung cancer is one of the leading causes of cancer-related deaths worldwide. One of the major reasons for this is the development of resistance against theurapatic drugs during treatment or due to genetic make up of tumors in patients. Although several molecular agents have been developed to overcome drug resistance, risk of recurrence is still being a challenge for efficient therapy at the present time. Thus, understanding chemoresistance mechanisms is crucial for successful treatment of this disease. In this study, it was aimed to establish drug-resistant sub-cell lines by mimicking treatment conditions of non-small cell lung cancer patients in vitro to study drug resistance mechanisms and to generate cell lines for future purposes to discover novel anti-chemoresistance agents. In accordance with this purpose, human non-small cell lung cancer cell line A549 was exposed to increasing concentrations of Epithelial Growth Factor Receptor targeting drug Erlotinib to create an Erlotinib resistant subline. To compare possible morphological and molecular changes during resistance development, a parental A549 subline was maintained in a parallel culture. The cell viability changes in both sublines were demonstrated by cell viability assays. Both groups of sublines were subjected to wound healing assay to monitor the differences in metastatic progression; on the other hand, tumorigenic capacities were measured by soft agar colony formation assays. Furthermore, the effects of Erlotinib on the gene expression changes of epithelial to mesenchymal transition markers, a key feature of chemoresistance, were detected by quantitative reverse transcription polymerase chain reaction analysis. It was found that besides increased cell viability under drug conditions, Erlotinib resistant subline was more tumorigenic with a greater migration capacity than the parental subline. Finally mesenchymal biomarker N-Cadherin gene expression was significantly increased in Erlotinib resistant subline.