@article{article_1742670, title={The lncRNA ATB–miR-200b Axis: Drug-Specific Regulation by Doxorubicin and Paclitaxel in ER-Positive Breast Cancer}, journal={Journal of Advanced Research in Health Sciences}, volume={8}, pages={132–137}, year={2025}, DOI={10.26650/JARHS2025-1742670}, author={Karpuzoğlu, Fatma Hande and Yenilmez Tunoğlu, Ezgi Nurdan}, keywords={Breast cancer, MCF-7 cell line, lncRNA ATB, miR-200b, doxorubicin, paclitaxel, RT-qPCR}, abstract={Objective: This study aimed to examine the expression patterns of long non-coding RNA ATB and microRNA-200b (miR-200b) in MCF-7 human breast cancer cells after treatment with two commonly used chemotherapeutic agents: doxorubicin (DOX) and paclitaxel (PTX). The goal was to determine whether the ATB–miR-200b regu latory axis influences drug-specific responses. Materials and Methods: MCF-7 cells were treated with IC₅₀ concentrations of DOX and PTX for 48 h. Total RNA was extracted, and cDNA was synthesised for both lncRNA and miRNA fractions. The expression levels of ATB and miR-200b were measured using quantitative real-time PCR (RT-qPCR). GAPDH and U6 served as internal references. Relative quantification was carried out using the 2−ΔΔCt method. Results: lncRNA ATB expression was significantly decreased in both treatment groups (p < 0.05). Interestingly, miR-200b expression was decreased in PTX-treated cells but moderately increased in DOX treated cells. These results indicate a different regulatory response of the ATB–miR-200b axis depending on the chemotherapeutic agent used. Conclusion: Our findings show that ATB and miR-200b respond differently to DOX and PTX exposure in MCF-7 cells. The simulta neous decrease of ATB and miR-200b in response to PTX may indicate EMT-related resistance mechanisms, whereas the increase of miR-200b in DOX-treated cells may be linked to apoptotic activation. More research is needed to understand the role of this regulatory axis in chemotherapy response.}, number={3}, publisher={Istanbul University}