Molecular characterization of irinotecan (SN-38) resistant human breast cancer cell lines
Haatisha Jandu1, Kristina Aluzaite2, Louise Fogh3
1Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark. jxm436@alumni.ku.dk.
Background:
Studies in taxane and/or anthracycline refractory metastatic breast cancer (mBC) patients have shown approximately 30% response rates to irinotecan. Hence, a significant number of patients will experience irinotecan-induced side effects without obtaining any benefit. The aim of this study was to lay the groundwork for development of predictive biomarkers for irinotecan treatment in BC.
Methods:
We established BC cell lines with acquired or de novo resistance to SN-38, by exposing the human BC cell lines MCF-7 and MDA-MB-231 to either stepwise increasing concentrations over 6 months or an initial high dose of SN-38 (the active metabolite of irinotecan), respectively. The resistant cell lines were analyzed for cross-resistance to other anti-cancer drugs, global gene expression, growth rates, TOP1 and TOP2A gene copy numbers and protein expression, and inhibition of the breast cancer resistance protein (ABCG2/BCRP) drug efflux pump.
Results:
We found that the resistant cell lines showed 7-100 fold increased resistance to SN-38 but remained sensitive to docetaxel and the non-camptothecin Top1 inhibitor LMP400. The resistant cell lines were characterized by Top1 down-regulation, changed isoelectric points of Top1 and reduced growth rates. The gene and protein expression of ABCG2/BCRP was up-regulated in the resistant sub-lines and functional assays revealed BCRP as a key mediator of SN-38 resistance.
Conclusions:
Based on our preclinical results, we suggest analyzing the predictive value of the BCRP in breast cancer patients scheduled for irinotecan treatment. Moreover, LMP400 should be tested in a clinical setting in breast cancer patients with resistance to irinotecan.
Insights
Predicting irinotecan response in breast cancer is crucial. This study identified breast cancer resistance protein (BCRP) as a key mediator of irinotecan resistance, suggesting its potential as a predictive biomarker.
Area of Science:
- Oncology
- Pharmacology
- Genetics
Background:
- Irinotecan shows limited efficacy in taxane/anthracycline-refractory metastatic breast cancer (mBC), with ~30% response rates.
- Many patients experience irinotecan side effects without benefit, highlighting the need for predictive biomarkers.
- This study aimed to develop predictive biomarkers for irinotecan treatment in breast cancer (BC).
Purpose of the Study:
- To establish and characterize irinotecan-resistant breast cancer (BC) cell lines.
- To identify mechanisms underlying resistance to SN-38, the active metabolite of irinotecan.
- To explore potential predictive biomarkers for irinotecan efficacy in BC.
Main Methods:
- Established acquired and de novo SN-38 resistant BC cell lines (MCF-7, MDA-MB-231).
- Analyzed cross-resistance, gene expression, growth rates, TOP1/TOP2A copy numbers, and breast cancer resistance protein (ABCG2/BCRP) expression.
- Utilized functional assays to determine BCRP's role in SN-38 resistance.
Main Results:
- Resistant cell lines exhibited 7-100 fold increased SN-38 resistance but remained sensitive to docetaxel and LMP400.
- Down-regulation of Top1, altered Top1 isoelectric points, and reduced growth rates were observed.
- Up-regulation of ABCG2/BCRP gene and protein expression was confirmed, with BCRP identified as a key mediator of SN-38 resistance.
Conclusions:
- Suggest analyzing the predictive value of BCRP in breast cancer patients undergoing irinotecan treatment.
- Recommend clinical evaluation of LMP400 in irinotecan-resistant breast cancer patients.
- Preclinical findings support BCRP as a potential biomarker for irinotecan response in BC.
More Related Videos
08:46Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
Published on: December 9, 2015
09:38Establishment and Characterization of Three Afatinib-resistant Lung Adenocarcinoma PC-9 Cell Lines Developed with Increasing Doses of Afatinib
Published on: June 26, 2019
