STAT3 mediates CAF-induced osimertinib resistance via regulating protein secretion in non-small cell lung cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors (EGFR-TKIs) show promise in Non-Small Cell Lung Cancer (NSCLC) treatment.
• Resistance to EGFR-TKIs, such as Osimertinib, remains a significant clinical challenge.
• The tumor microenvironment's role in mediating drug resistance is increasingly recognized.

Purpose of the Study:

• To elucidate the mechanism by which the tumor microenvironment induces Osimertinib resistance in NSCLC.
• To identify key molecular players involved in this resistance mechanism.
• To evaluate the potential of targeting these players to overcome Osimertinib resistance.

Main Methods:

• In vitro assays including CCK-8, wound healing, Transwell, and colony formation assays.
• Western blot for protein expression analysis.
• In vivo xenograft studies and immunohistochemistry for assessing antitumor efficacy and target expression.
• Statistical analysis using t-test/ANOVA.

Main Results:

• Cancer-associated fibroblasts (CAFs) within the tumor microenvironment were identified as inducers of Osimertinib resistance in NSCLC.
• CAF-induced resistance is mediated through secreted proteins.
• Signal transducer and activator of transcription 3 (STAT3) was found to be crucial for CAF activation and protein secretion.
• Knockdown of STAT3 or inhibition of STAT3 activation in CAFs using the novel inhibitor LL1 effectively reversed Osimertinib resistance.

Conclusions:

• The tumor microenvironment, specifically CAFs, plays a critical role in mediating Osimertinib resistance in NSCLC.
• STAT3 is a key regulator of CAF-mediated resistance.
• Targeting STAT3 activation in CAFs with agents like LL1 presents a promising strategy for overcoming EGFR-TKI resistance in NSCLC.