Cancer Stem Cell Biomarkers in EGFR-Mutation-Positive Non-Small-Cell Lung Cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Stem Cell Research

Background:

• Deregulation of the epidermal growth factor receptor (EGFR) pathway is implicated in non-small-cell lung cancer (NSCLC) development and the acquisition of stem-like properties.
• EGFR inhibition can paradoxically enrich for lung cancer stem cells (CSCs) through mechanisms involving NOTCH signaling, Src, Yes-associated protein 1 (YAP1), and Signal Transduction and Activator of Transcription 3 (STAT3).

Purpose of the Study:

• To investigate the enrichment of aldehyde dehydrogenase (ALDH)-positive cells, a marker for CSCs, in EGFR-mutation-positive NSCLC cells treated with EGFR inhibitors.
• To evaluate the expression of CSC markers and identify predictive biomarkers for treatment outcomes in patients receiving EGFR blockade.

Main Methods:

• Aldefluor assay and Western blot analysis were used to assess CSC enrichment and marker expression in EGFR-mutation-positive NSCLC cells treated with gefitinib, afatinib, and osimertinib.
• Gene expression analysis was performed on a cohort of 64 EGFR-mutation-positive NSCLC patients to correlate specific gene expression profiles with treatment outcomes.

Main Results:

• EGFR inhibition led to an enrichment of ALDH-positive cells with elevated CSC marker expression.
• Concurrent inhibition of EGFR, STAT3, and Src significantly reduced the CSC subpopulation in an EGFR-mutation-positive cellular model.
• High expression of ALDH1 isoforms, NOTCH target HES1, and Bmi-1 were predictive of worse outcomes in patients treated with EGFR inhibitors.

Conclusions:

• Single-agent EGFR inhibitors can increase CSC populations in NSCLC.
• Combinatorial therapies targeting STAT3 and Src may offer a therapeutic benefit in overcoming resistance to EGFR inhibition.
• ALDH1, HES1, and Bmi-1 serve as crucial biomarkers for initial patient assessment and predicting treatment response in EGFR-mutation-positive NSCLC.