Simvastatin overcomes resistance to tyrosine kinase inhibitors in patient-derived, oncogene-driven lung adenocarcinoma models
There is an unmet clinical need to develop novel strategies to overcome resistance to tyrosine kinase inhibitors (TKIs) in patients with oncogene-driven lung adenocarcinoma (LUAD). Statins is a class of drugs that act as competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR). The objective of this study was to determine if simvastatin could overcome TKI resistance using the vivo LUAD models. Mice implanted with patient-derived xenografts (PDXs) from osmertinib-resistant LUAD were treated with simvastatin, either alone or in combination with osmertinib. Tumors were assessed by RNA sequencing. RNA sequencing  identified the proliferation, migration, and invasion-related genes (such as PI3K/Akt/mTOR, YAP/TAZ, focal adhesion, extracellular matrix receptor), proteasome-related genes, and integrin (a3ß1, avß3) signaling pathways are significantly changed in these PDX tumors treated with simvastatin and the combo therapy. Overall design: A PDX model was generated from patients with metastatic LUAD harboring oncogenic mutations (EGFR L858) and implanted into the flank of NSG mice at 5-6 weeks of age. Treatment was initiated at week three or when tumors reached an average size of 150-200 mm3. Mice were randomized into control and treatment groups, with 4 mice per group. They received vehicle control, single-agent treatment (osimertinib or simvastatin), or osimertinib and simvastatin combination therapy.  Total RNA was isolated from 10 mg of tumor tissue using the RNeasy Mini Kit (Qiagen) following the manufacturer's protocol. RNA-sequencing was performed at Novogene Corporation Inc. (https://en.novogene.com), which performed the quality control analysis and constructed the library using TruSeq Stranded Total RNA Sample Prep Kit (Illumina). The sequencing was performed on the NovaSeq 6000 system (NovaSeq PE150) at the Novogene UC Davis Sequencing Center. The raw sequencing data were obtained for analysis. Reads were aligned to Human hg38 using Salmon with standard settings