Group IIa secretory phospholipase expression correlates with group IIa secretory phospholipase inhibition–mediated cell death in K-ras mutant lung cancer cells

ObjectiveThere are currently no targeted therapies against lung tumors with oncogenic K-ras mutations that are found in 25% to -40% of lung cancers and are characterized by their resistance to epidermal growth factor receptor inhibitors. The isozyme group IIa secretory phospholipase A2 (sPLA2IIa) is a potential biomarker and regulator of lung cancer cell invasion; however, the relationship between K-ras mutations and sPLA2IIa has yet to be investigated. We hypothesize that sPLA2IIa modulates lung cancer cell growth in K-ras mutant cells and that sPLA2IIa expression in human lung tumors is increased in K-ras mutant tumors.MethodsBaseline sPLA2IIa expression in K-ras mutant lung cancer cell lines (A549, SW1573, H358, H2009) was assessed. Cells were treated with a specific sPLA2IIa inhibitor and evaluated for apoptosis and cell viability. Nuclear factor kappa-b (NF-κB) and extracellular signal-regulated kinase 1/2 activity were detected by Western blot. Human tumor samples were evaluated for sPLA2IIa mRNA expression by quantitative reverse-transcription polymerase chain reaction.ResultsCytotoxicity of sPLA2IIa inhibition correlates with sPLA2IIa expression. Apoptosis in response to sPLA2 inhibition parallels attenuation in NF-κB activity. In addition, sPLA2IIa expression in human tumors correlates with squamous cell pathology and increasing stage of K-ras mutant lung tumors.ConclusionsBaseline sPLA2IIa expression predicts response to sPLA2IIa inhibition in some K-ras mutant lung cancer cells. This finding is independent of p53 mutation status. Furthermore, squamous tumors and advanced-stage K-ras mutant tumors express more sPLA2IIa. These data support a role for sPLA2IIa as a potential global therapeutic target in the treatment of lung cancer