NF-κB信号的激活驱动STK11缺陷型肺腺癌的促转移程序

Lung cancer remains the leading cause of cancer-related deaths worldwide and is characterized by marked clinical aggressiveness, including high rates of therapy resistance and metastatic progression. Although recent therapeutic advances have modestly improved 5-year survival in lung cancer, overall response rates remain low (~25%), and effective treatments for metastatic disease are limited. A particularly strong genotype-phenotype correlation predicting broad treatment resistance, early disease dissemination, and poor overall survival in KRAS-driven lung adenocarcinomas (LUADs) is loss of the Serine/Threonine kinase 11 (STK11) tumor suppressor. Patients with STK11-deficient tumors commonly present with advanced-stage disease, exhibit enhanced metastatic potential and experience an especially aggressive clinical course. Despite these well-established clinical associations, the molecular mechanisms driving this aggressive, treatment-refractory phenotype remain largely undefined. We performed whole transcriptome and pathway enrichment studies comparing a KRAS-driven/STK11-competent LUAD (K) cell line with KRAS-driven/STK11-null (KS) cell line and identified STK11-loss-dependent activation of the NF-kappa B (NF-κB) signaling pathway in response to glutamine deprivation. Kmeans clustering of the RNA transcripts highlighted 36 genes induced upon glutamine depletion in KS cells. These genes were subsequently downregulated in the absence of the NF-κB transcription factor (p65) through genetic ablation or pharmacological inhibition (using PS-1145 ), with corresponding decreases in protein expression of candidate oncogenes and anti-apoptotic markers. These findings indicate that NF-κB activation is essential for transcriptional induction of survival, proliferation, and premetastatic genes under glutamine stress. We then showed that p65 consistently accumulates in the nucleus of KS cells following the removal of glutamine, suggesting transcriptional regulation through NF-κB signaling. Following pharmacological inhibition of NF-κB and glutamine depletion, p65 was unable to translocate into the nucleus and was sequestered in the cytoplasm of KS cells. To assess whether glutamine stress and NF-κB signaling promote metastasis we used a 3D spheroid model. Spheroid models more closely mimic the microenvironment of in vivo tumors, in which nutrients and oxygen become restricted. Glutamine deprivation enhanced ameboid-like single-cell invasion in KS spheroids, an effect markedly reduced by p65 knockout or PS-1145 treatment. Using a combination of transcriptomic analyses and in vitro invasion assays to model metastasis, these results suggest that STK11 loss in KRAS driven lung adenocarcinoma promotes an NF-κB-dependent metastatic phenotypes.