• A549
• AKR1B1
• anthracyclines
• chemoresistance
• chemotherapy
• daunorubicin
• DNB
• drug detoxification
• EMT
• epithelial-mesenchymal transition
• lung cancer
• non-small cell lung cancer
• NSCLC

The efficacy of anti-cancer therapies is often compromised by the development of drug resistance, a phenomenon in which cancer cells acquire the ability to evade the cytotoxic effects of treatment. Drug resistance is responsible for over 90% of cancer-related deaths, making it one of the most critical challenges in oncology research.
In this study, the human A549 alveolar basal adenocarcinoma cell line was used as a model for non-small cell lung cancer (NSCLC). This cell line is widely employed to evaluate the effectiveness of chemotherapeutic agents, including the anthracycline daunorubicin (DNB), which was used here as a representative compound of the anthracycline class. A major challenge in DNB-based treatment is its rapid intracellular metabolism by oxidoreductase enzymes, such as short-chain dehydrogenases and aldo-keto reductases. This metabolic activity reduces the cytotoxicity of DNB, diminishes its therapeutic efficacy, and generates cardiotoxic metabolites.
Previous work in our laboratory established a daunorubicin-resistant A549 cell line (A549DNB) through prolonged exposure to a low concentration of DNB (50 nM) over a period of four weeks. These cells exhibited marked morphological and functional alterations, including mesenchymal-like features. Therefore, the present study aims to investigate the molecular mechanisms underlying chemoresistance, epithelial-to-mesenchymal transition (EMT), and drug detoxification by comparing A549DNB cells with the corresponding control cell line (A549CONT), which was cultured in parallel for the same duration in the presence of DMSO.
The activation of drug detoxification pathways was assessed by evaluating the differential expression of multidrug resistance protein 1 (MRP1) in both A549DNB and A549CONT cell lines through RT-PCR, Western blotting, and confocal fluorescence microscopy, as well as by analyzing the activation of autophagic processes. EMT induction was further investigated by measuring the expression of specific EMT markers, including N-cadherin, E-cadherin, and TGF-β. Differences in cellular proliferation were assessed using the Sulforhodamine B (SRB) assay, while alterations in migratory capacity were analyzed using the wound healing assay.
Furthermore, cell viability was determined via MTT assays to evaluate the cytotoxic effects of DNB and assess differences in chemoresistance between the two cell lines. Differential expression of proteins involved in key cellular pathways was evaluated using both RT-PCR and Western blot analysis. Finally, the impact of drug treatment on cellular metabolic activity was assessed by capillary electrophoresis and spectrophotometric analysis.
Collectively, the experimental results reveal substantial modulation of multiple cellular parameters in response to chemotherapeutic treatment, offering valuable insights into the complex interplay between chemoresistance, EMT, and metabolic adaptation in a non-small cell lung cancer model.