Abstract 3354: The level of aerobic glycolysis as an effective predictor of tumorigenicity
Authors: Lee Doo Young , Park Young Jin , Bae Jung Yoon , Kim Jin 
Published: May 2015

Introduction: Cancer cells have been known to harbor characteristic metabolic alterations such as enhanced glucose uptake and aerobic glycolysis. However, elucidation of molecular mechanisms underlying the association between aerobic glycolysis and tumorigenesis has remained elusive. Thus, this study aimed to investigate the role of altered metabolism in conferring advantage to tumorigenesis, using two different cell lines of immortalized human oral keratinocytes (IHOK) that differed in the level of aerobic glycolysis.

Experimental procedures: Levels of glucose uptake and lactate production were measured. Reverse transcription polymerase chain reaction and western blot were employed to measure the expression of relevant genes. Proteomic analysis was performed to identify protein-level differences. Small interfering RNAs were used for transient knockdown of genes. The cell lines were injected into mouse tongue to assess subsequent tumor formation.

Results: Although the two IHOK cell lines shared same origin, the cell line with enhanced glucose uptake and lactate production also had higher expression of genes involved in glycolysis, growth signal propagation, and matrix remodeling. In particular, matrix metalloproteinase (MMP)-1, 2, 9, and 14 expressions were significantly higher in the cell line with upregulated glycolysis. Upon injection into mice, the two cell lines differed in the rate of in vivo tumor formation and resulting tumor volume.

Epidermal growth factor receptor (EGFR) was upregulated in the more tumorigenic IHOK cell line as well as in aggressive breast and oral cancer cell lines compared with their less aggressive counterparts. EGFR knockdown in the more tumorigenic cell lines led to reduction in lactate production and prevented high-level expression of glycolytic genes normally induced by EGF treatment.

Proteomic analysis between the two IHOK cell lines revealed pyruvate kinase isozyme M2 (PKM2) as the protein whose level was significantly higher in the more tumorigenic cell line. To evaluate the relationship between upregulated PKM2 and high tumorigenic potentials, PKM2 was knocked down in the more tumorigenic cell line. MMP-1 level decreased upon PKM2 knockdown, indicating that upregulated PKM2 not only promotes aerobic glycolysis but also enhances MMP expression to facilitate tumorigenesis.

Conclusions: Cells with upregulated PKM2 likely excel in tumorigenesis by enhancing MMP expression. In addition, upregulated EGFR amplifies the growth signals to enhance the expression of genes required for tumor progression. These results indicate that the degree of altered metabolic activity, aerobic glycolysis in particular, might be a significant predictor of tumorigenicity.

Acknowledgements: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2009-0094027).

Citation Format: Doo Young Lee, Young Jin Park, Jung Yoon Bae, Jin Kim. The level of aerobic glycolysis as an effective predictor of tumorigenicity. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3354. doi:10.1158/1538-7445.AM2014-3354