Identification of dynamic network biomarker ITGB1 for erlotinib pre-resistance using single-cell differential covariance entropy

Acquired erlotinib resistance is the primary cause of treatment failure in patients with non-small cell lung cancer (NSCLC). Most current research focuses on end-stage resistance, whereas early events leading to resistance have been largely overlooked. In this study, we developed a novel dynamic network biomarker (DNB) method called single-cell differential covariance entropy (scDCE) to identify the pre-resistance state and associated DNB genes. We identified the DNB core gene <i>ITGB1</i> using protein-protein interactions (PPIs) and Mendelian randomization (MR) analyses. Cell Counting Kit-8 assay demonstrated that <i>ITGB1</i> downregulation increases the sensitivity of PC9 cells to erlotinib. Survival analyses suggested that high <i>ITGB1</i> expression was associated with poor prognosis in NSCLC. Mechanistically, we found that <i>ITGB1</i> and DNB-neighboring genes were significantly enriched in the focal adhesion pathway, where <i>ITGB1</i> upregulates the expression of <i>PTK2</i> (focal adhesion kinase), leading to phosphorylation of downstream effectors, which activated the PI3K-Akt and MAPK signaling pathways to promote cell proliferation and mediate erlotinib resistance. Additionally, the transcription factor <i>MAX</i>/<i>MNT</i> binds to the <i>ITGB1</i> promoter, synergistically regulating its expression. The experiment also shows that the erlotinib-trametinib combination therapy effectively inhibits resistance. These findings provide new clues for future research on erlotinib resistance mechanisms and early intervention.