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  P3.01 - Poster Session 3 - Cancer Biology (ID 147)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

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    P3.01-007 - Energy metabolism in lung adenocarcinoma (ID 2557)

    09:30 - 09:30  |  Author(s): Y. Xu
    • Abstract

    Background
    Cancer cells have defects in regulatory circuits governing proliferation and homeostasis. Consequently, cell metabolism is altered to meet the demand for accelerated, deregulated growth. Metabolic perturbations arising from malignant transformation have not been well characterized in human lung cancers in situ. The most well known metabolic derangement(s) in tumors is that of enhanced glycolysis and a decrease in mitochondrial oxidative phosphorylation. We wanted to characterize this phenomenon more accurately in human lung adenocarcinomas by metabolomic profiling.

    Methods
    We performed metabolomic analysis of matched pairs of solid, non-small cell lung adenocarcinomas and normal lung tissue from 25 surgically resected patients. Metabolites were extracted by a methanol-chloroform-water technique. The resulting extracts were divided into multiple fractions. Ultrahigh performance liquid chromatography/ mass spectrometry coupled with tandem mass spectrometry and gas chromatography/ mass spectrometry experiments were conducted. Agilent MassHunter Qualitative software was utilized. The Molecular Feature Extractor was utilized to find features in raw data files. Extracted peaks were retention time aligned using Mass Profiler Professional and unique features detected by least squares analysis. The Agilent version of the Metlin database was utilized to identify metabolites. Matched pairs t-test identified biochemicals significantly altered between tumor and normal specimens. The false discovery rate method assessed for significance; p-value ≤ 0.05 and q-value < 0.10.

    Results
    Based on known library standards to identify biochemicals, our global metabolomic profiling found 204 overexpressed and 42 underexpressed metabolites in tumors relative to normal lung (p< 0.05). We observed altered metabolite levels in lung tumors that mapped to not one, but two glucose utilization pathways. Glucose-6-P (2.7-fold), fructose-6-P (2.6-fold), fructose-1,6-bisP (6.9-fold), lactate (2.7-fold), and NAD[+] (1.4-fold) were significantly upregulated in tumors consistent with an aerobic glycolysis (i.e. Warburg) biosignature, the major source of ATP. Concurrently, pentose phosphate pathway (PPP) metabolites were upregulated in tumors: ribulose-5-P (2.6-fold), ribulose (3.6-fold), ribitol (4.6-fold), ribose (4-fold), and sedoheptulose-7-P (3-fold). Our data reveals evidence of multiple active pathways to explain glucose utilization in lung adenocarcinomas. The PPP is important to protect against oxidative stress as it serves to generate NADPH, and is a key anabolic pathway of nucleotide synthesis by generating the ribose-5-P backbone for proliferating cells. Observing both pathways simultaneously in lung adenocarcinomas suggests they are coupled to give tumors a growth advantage over normal tissue. Consistent with this, we observed an overall increasing nucleotide biosynthesis signature in tumors: multiple metabolites (range 2 to 17-fold) in purine and pyrimidine pathways were significantly elevated.

    Conclusion
    Metabolomic analysis identified a unique glucose energetic biosignature in lung tumors that is more complex that just a single process/ pathway. Our results suggest a specific strategy to target lung adenocarcinomas by exploiting their high glucose uptake.