LPIN2 contributes to tyrosine kinase inhibitor resistance via activation of PI3K pathway

Acquired resistance to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) is a critical clinical barrier. While metabolic reprogramming is implicated in target-independent resistance, the specific role of triglyceride (TG) synthesis remains unclear. Objective: This study aims to systematically elucidate the precise role and underlying mechanisms of LPIN2-mediated lipid metabolic reprogramming in TKI resistance, and to explore potential metabolic-targeted combination therapies for NSCLC.

Osimertinib-resistant (PC-9 OR) and alectinib-resistant (NCI-H3122 ALR) cell lines were established via a dose-escalation strategy. The resistant cells were then compared with their original sensitive cells under both drug-present and drug-withdrawn conditions. Metabolomic liquid chromatography-mass spectrometry (LC-MS) and transcriptomic analyses revealed shared differential features, which were selected as candidate key metabolic enzymes in TKI resistance. From this pathway, LPIN2 was selected as a consistently upregulated key enzyme for validation. The LPIN2 gene was knocked out using CRISPR/Cas9 technology; a series of functional assays (e.g., drug sensitivity, colony formation), complemented by lipid supplementation, pathway inhibition (PI3K/mTOR), and a mouse xenograft model to verify the underlying mechanism.

LPIN2 was identified as a key driver of TKI resistance in NSCLC, with its mRNA and protein levels significantly upregulated (~2-fold) in osimertinib-resistant (PC-9 OR) and alectinib-resistant (NCI-H3122 ALR) cells. CRISPR/Cas9-mediated LPIN2 knockout restored TKI sensitivity, displaying oncogene-specific magnitudes of reduction in the half-maximal inhibitory concentration (IC₅₀): decreasing from 3,585 nM to 229-477 nM in EGFR-mutant PC-9 OR cells, and exhibiting a more moderate reduction from 2,264 nM to 325-488 nM in ALK-fusion NCI-H3122 ALR cells, while suppressing tumor growth in vivo (Ki67 downregulation). Mechanistically, LPIN2 promoted TG accumulation and lipid droplet deposition; exogenous TG supplementation (1,2-dioleoyl-3-arachidoyl-sn-glycerol) induced TKI resistance in parental cells and rescued drug tolerance in LPIN2-knockout cells, whereas inhibition of downstream TG synthesis enzymes [diacylglycerol O-acyltransferase1/2 (DGAT1/2)] recapitulated the knockout phenotype. Furthermore, perturbation of the LPIN2-TG axis was associated with modulation of the PI3K-AKT-mTOR survival pathway, regulating apoptosis-related proteins (BCL-XL/BCL2 downregulation, BAX upregulation). Combined treatment with osimertinib and a PI3K inhibitor (Wortmannin) synergistically suppressed tumor growth and prolonged survival in xenograft models.

LPIN2 contributes to TKI resistance in NSCLC through a novel LPIN2-TG metabolic node that is functionally associated with PI3K-AKT signaling: it enhances TG biosynthesis and lipid droplet accumulation, thereby indirectly modulating the PI3K-AKT pathway to inhibit apoptosis. Targeting this axis reverses TKI resistance in vitro and in vivo, identifying LPIN2 as a drug stress-independent resistance driver and potential biomarker for metabolic-targeted combination therapy.