Re-expression of LKB1 in LKB1-mutant EKVX cells leads to resistance to paclitaxel through the up-regulation of MDR1 expression

• Type of Material: Article
• Authors: Kaisheng Mao, Emory University; Fakeng Liu, Emory University; Xiuju Liu, Emory University; Fadlo Khuri, Emory University; Adam Marcus, Emory University; Mingsong Li, NanFang Hosp; Wei Zhou, Emory University
• Language: English
• Date: 2015-05-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2015 Elsevier Ireland Ltd.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.lungcan.2015.02.017
• Title of Journal or Parent Work: Lung Cancer
• ISSN: 0169-5002
• Volume: 88
• Issue: 2
• Start Page: 131
• End Page: 138
• Grant/Funding Information: This study was supported by PERPG 2011B09040056 (M. Li), NIH grant R01-CA140571 (W. Zhou), P01 CA116676 (F.R. Khuri), China Scholarship Council (F. Liu), and Anise McDaniel Brock Scholar fund (W. Zhou).; This research project was also supported in part by the Emory University Integrated Cellular Imaging Microscopy Core of the Winship Cancer Institute comprehensive cancer center grant, P30CA138292.
• Keywords: PROTEINS; PHOSPHORYLATION; Microtubule targeting agents; Serine/threonine kinase; Life Sciences & Biomedicine; Paclitaxel resistance; Tumor suppressor; LUNG-CANCER; Multi-drug resistance; Oncology; Promoter methylation; CHEMOTHERAPY; Respiratory System; TAU
• Research Categories: Health Sciences, Pharmacology; Health Sciences, Oncology

Abstract

Objectives: The tumor suppressor LKB1 has recently been shown to be involved in the regulation of microtubule dynamics, thus cancer cells with inactivated LKB1 may have developed a means to overcome dysregulated microtubule functions, making them intrinsically resistant to microtubule targeting agents. Here, we generated isogenic LKB1-wild type and mutant non-small cell lung cancer (NSCLC) cell lines to evaluate the role of LKB1 in paclitaxel resistance. Materials and methods: SRB, flow cytometry and immunoblotting were used to assess cell proliferation and apoptosis in NSCLC cell lines after paclitaxel treatment. Expression of LKB1 was restored in LKB1-null cells by retrovirus infection and was reduced in LKB1-wild type cells by shRNA knock down. Results and conclusion: The restoration of LKB1 in LKB1-null cells failed to promote paclitaxel-induced apoptosis in both p53-wild type and p53-mutant backgrounds, indicating that LKB1 was not required for paclitaxel-induced apoptosis. Interestingly, the re-establishment of LKB1 expression led to the up-regulation of class III beta-tubulin and MDR1 in EKVX cells. The up-regulation of MDR1 protein and transcripts in EKVX cells was specifically associated with the expression of wild-type LKB1 and mainly responsible for the increased cellular resistance to paclitaxel. However, the presence of LKB1 protein was not required to maintain this increased MDR1 expression even though there was no genetic amplification or promoter de-methylation of the ABCB1 locus in EKVX-LKB1-WT cells. These data suggest that LKB1 does not promote paclitaxel-induced apoptosis in most NSCLC cell lines. In contrast, in some NSCLC, the presence of LKB1 may facilitate increases in either MDR1 or class III beta-tubulin expression which can lead to paclitaxel resistance.