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Updated: Feb 10, 2026
Radiosensitivity of Cancer Stem Cells in Lung Cancer Cell Lines
Published on: August 21, 2019
Characterization of carfilzomib-resistant non-small cell lung cancer cell lines
Neale T Hanke1, Elliot Imler2, Marilyn T Marron2
1College of Medicine, University of Arizona Cancer Center, Tucson, AZ, USA.
Purpose:
We previously showed that carfilzomib (CFZ) has potent anti-proliferative and cytotoxic activity in a broad range of lung cancer cell lines. Here we investigate possible mechanisms of CFZ acquired resistance in lung cancer cell lines.
Methods:
CFZ-resistant non-small cell lung cancer (NSCLC) cell lines were developed by exposing A549 and H520 cells to stepwise increasing concentrations of CFZ. Resistance to CFZ and cross-resistance to bortezomib and other chemotherapy drugs was measured using the MTT assay. Cytotoxicity to CFZ was determined using a CytoTox assay. Western blot was used to measure apoptosis, autophagy, and drug efflux transporter-related proteins. Quantitative targeted whole transcriptome sequencing and quantitative RT-PCR was used to measure gene expression. Flow cytometry was used to analyze intracellular accumulation of doxorubicin.
Results:
The CFZ IC50 value of the resistant cells increased versus parental lines (2.5-fold for A549, 122-fold for H520). Resistant lines showed reduced expression of apoptosis and autophagy markers and reduced death versus parental lines following CFZ treatment. Both resistant lines exhibited higher P-glycoprotein (Pgp) gene (TempO-Seq® analysis, increased 1.2-fold in A549, > 9000-fold in H520) and protein expression levels versus parental lines. TempO-Seq® analysis indicated other drug resistance pathways were upregulated. The resistant cell lines demonstrated less accumulation of intracellular doxorubicin, and were cross-resistant to other Pgp client drugs: bortezomib, doxorubicin, and paclitaxel, but not cisplatin.
Conclusions:
Upregulation of Pgp appears to be an important, but not the only, mechanism of CFZ resistance in NSCLC cell lines.
Insights
Carfilzomib resistance in lung cancer cells involves increased P-glycoprotein (Pgp) expression, reducing drug accumulation and effectiveness. This highlights Pgp as a key factor in acquired resistance to carfilzomib (CFZ) in non-small cell lung cancer (NSCLC).
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Carfilzomib (CFZ) demonstrates significant anti-proliferative and cytotoxic effects against lung cancer cell lines.
- Understanding acquired resistance mechanisms is crucial for optimizing CFZ therapy in non-small cell lung cancer (NSCLC).
Purpose of the Study:
- To investigate the molecular mechanisms underlying acquired resistance to carfilzomib (CFZ) in non-small cell lung cancer (NSCLC) cell lines.
- To assess cross-resistance patterns to other chemotherapeutic agents in CFZ-resistant cells.
Main Methods:
- Development of CFZ-resistant NSCLC cell lines (A549, H520) through stepwise drug exposure.
- Assessment of drug resistance via MTT assays and cytotoxicity using CytoTox assays.
- Analysis of apoptosis, autophagy, drug efflux proteins (P-glycoprotein), and gene expression using Western blot and TempO-Seq® sequencing.
Main Results:
- CFZ-resistant cell lines exhibited significantly increased IC50 values (2.5-fold in A549, 122-fold in H520).
- Resistant cells showed reduced apoptosis and autophagy markers, along with decreased sensitivity to CFZ.
- Upregulation of P-glycoprotein (Pgp) gene and protein expression was observed (1.2-fold in A549, >9000-fold in H520), correlating with reduced intracellular doxorubicin accumulation and cross-resistance to Pgp substrates like bortezomib, doxorubicin, and paclitaxel.
Conclusions:
- P-glycoprotein (Pgp) upregulation is a significant mechanism contributing to carfilzomib (CFZ) resistance in NSCLC.
- Other drug resistance pathways are also implicated, suggesting multifactorial resistance mechanisms.
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