Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
Project description:Glutamine is a key nutrient for tumor cells that supports nucleotide and amino acid biosynthesis, replenishes the TCA cycle intermediates and contributes to redox metabolism. We identified oncogenic KRAS as a critical regulator of the response to glutamine deprivation in NSCLC. Full activation of the ATF4 stress response pathway is dependent on expression of NRF2 downstream of oncogenic KRAS in NSCLC. Through this mechanism, KRAS alters amino acid uptake and metabolism and sustains mTORC1 signaling during nutrient stress. Furthermore, we identified regulation of asparagine synthetase (ASNS) as a key effect of oncogenic KRAS signaling via ATF4 during glutamine deprivation, and a potential therapeutic target in KRAS mutant NSCLC.
Project description:Oncogenic STAT3 functions are known in various malignancies. We found that STAT3 plays an unexpected tumor suppressive role in KRAS-mutant non-small-cell-lung cancer (NSCLC). In mice, tissue-specific inactivation of Stat3 resulted in increased Kras (G12D)-driven NSCLC initiation and malignant progression leading to markedly reduced survival. Clinically, low STAT3 expression levels correlate with poor survival in human lung adenocarcinoma patients with smoking history. Consistently, KRAS-mutant lung tumors showed reduced STAT3 levels. Mechanistically, we show that STAT3 controls NFκB-induced IL-8-expression by sequestering NFκB in the cytoplasm while IL-8 in turn regulates myeloid tumor infiltration and tumor vascularization thereby promoting tumor progression. These results identify a novel STAT3-NFκB-IL-8 axis in KRAS-mutant NSCLC with therapeutic and prognostic relevance WT: Control lung; KRAS: Lung tumors expressing KRAS G12D; KRAS STAT3 KO: Lung tumors expressing KRAS G12D- STAT3 deficient; tumors of four mice pooled per sample
Project description:Since both KRAS mutations and LKB1 inactivating alterations affect cellular metabolism, it seems propitious to discern metabolic effects induced by the single oncogenic events from those elicited by their co-occurrence, with the ultimate aim to potentially exploit metabolic dependencies for novel therapeutic modalities. With these considerations in mind, we knocked-out the LKB1 gene in well-characterized NSCLC cell clones harboring KRAS WT or mutant G12C proteins (13,30). We obtained an isogenic system in which KRAS mutation and LKB1 inactivation were individually or concomitantly present. The effects of the genetic lesions individually or together on cell metabolism were investigated in these isogenic NSCLC cells by means of an integrated survey of proteomics, stable and dynamic metabolomics and functional in-vitro strategies.
Project description:Mutant KRAS (mut-KRAS) is present in 30% of all human cancers and plays a critical role in cancer cell growth and resistance to therapy. There is evidence from colon cancer that mut-KRAS is a poor prognostic factor and negative predictor of patient response to molecularly targeted therapy. However, evidence for such a relationship in non small cell lung cancer (NSCLC) is conflicting. KRAS mutations are primarily found at codons 12 and 13, where different base changes lead to alternate amino acid substitutions that lock the protein in an active state. The patterns of mut-KRas amino acid substitutions in colon cancer and NSCLC are quite different, with aspartate (D) predominating in colon cancer (50%) and cysteine (C) in NSCLC (47%). Through an analysis of a recently completed biopsy biomarker-driven, molecularly targeted multi-arm trial of 215 evaluable patients with refractory NSCLC we show that mut-KRas-G12C/V but not total mut-KRAS predicts progression free survival for the overall group, and for the sorafenib and vandetanib treatment arms. Transcriptome microarray data shows differential expression of cell cycle genes between mut-KRas-G12C/V and G12D patient tumors. A panel of NSCLC cell lines with known mut-KRas amino acid substitutions was used to identify pathways activated by the different mut-KRas, showing that mut-KRas-G12D activates both PI-3-K and MEK signaling, while mut-KRas G12C does not, and alternatively activates RAL signaling. This finding was confirmed using immortalized human bronchial epithelial cells stably transfected with wt-KRAS and different forms of mut-KRAS. Molecular modeling studies show that the different conformation imposed by mut-KRas-G12C could lead to altered association with downstream signaling transducers compared to wild type and mut-KRas-G12D. The significance of the findings for developing mut-KRAS therapies is profound, since it suggests that not all mut-KRas amino acid substitutions signal to effectors in a similar way, and may require different therapeutic interventions. Gene expression profiles were measured in 22 core biopsies from patients with refractory non-small cell lung cancer included in the Biomarker-integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE). All tumors were KRAS mutants, but with different patterns of amino acid substitutions. Supervised analysis of transcriptome profiling was performed to compare cysteine or valine KRAS mutants with other KRAS mutants.
Project description:Oncogenic KRAS mutations are a key driver for initiation and progression in non-small-cell lung cancer (NSCLC). However, how post-translational modifications (PTMs) of KRAS, especially methylation, modify KRAS activity remain largely unclear. Here, we show that SET domain containing histone lysine methyltransferase 7 (SETD7) interacts with KRAS and methylates KRAS at lysines 182 and 184. SETD7-mediated methylation of KRAS leads to degradation of KRAS and attenuation of the RAS/MEK/ERK signaling cascade, endowing SETD7 with a potent tumor-suppressive role in NSCLC, both in vitro and in vivo. Mechanistically, RABGEF1, a ubiquitin E3 ligase of KRAS, was recruited and promoted KRAS degradation in a K182/K184 methylation-dependent manner. Notably, SETD7 is inversely correlated with KRAS at the protein level in clinical NSCLC tissues. Low SETD7 or RABGEF1 expression is associated with poor prognosis in lung adenocarcinoma patients. Altogether, our results elucidate a tumor-suppressive function of SETD7 that operates via modulating KRAS methylation and degradation.