Abstract 4411: Loss of fructose-1,6-bisphosphatase expression induces altering glucose metabolism and tumor progression in hepatocellular carcinoma

Abstract

Abstract Background: A recent study reported the loss of gluconeogenic capacity in hepatocellular carcinoma (HCC). Fructose-1,6-bisphosphatase (FBP1), the rate-limiting enzyme in gluconeogenesis, is reduced in expression in some cancers. However, the role of FBP1 in altered glucose metabolism in HCC was unclear. Therefore, the objective of this study was to examine the function and clinical significance of FBP1 expression in HCC. Materials and Methods: First, three independent cohorts totaling 594 cases of HCC (118 real-time RT-PCR data from our institution, 242 expression array data from GSE14520, and 234 RNA-sequencing data from The Cancer Genome Atlas (TCGA)) were analyzed to address clinical significance. Data from methylation arrays, SNP arrays, and whole-exome sequencing were also analyzed to investigate the regulation of FBP1 expression in the TCGA cohort. Second, we analyzed mRNA expression, promoter methylation, and DNA copy number profiles of 967 human cancer cell lines, including 27 liver cancer, in the Cancer Cell Line Encyclopedia. Third, we established HCC cell lines stably expressing FBP1 or empty vector control. We performed sphere formation assay and xenograft studies to evaluate the role of FBP1 on HCC progression. Furthermore, in order to assess the effect of FBP1 on altered glucose metabolism, isotopomer distribution analysis was performed using [U-13C] glucose. Finally, to validate the effects of FBP1 expression on survival, risk of recurrence, and glucose metabolism, we performed gene set enrichment analysis (GSEA). Results: Lower FBP1 expression associated with advanced tumor stage, poor overall survival (OS), and poor recurrence-free survival (RFS) in three independent HCC cohorts. For either OS or RFS in each cohort, this prognostic impact persisted, even after adjusting for tumor stage. In HCC cell lines, where endogenous FBP1 expression is low, engineering its ectopic overexpression inhibited tumor growth and intracellular glucose uptake by reducing aerobic glycolysis. In patient specimens, promoter methylation and copy-number loss of FBP1 were independently associated with decreased FBP1 expression. Similarly, FBP1 downregulation in HCC cell lines was also associated with copy-number loss. HCC specimens exhibiting low expression of FBP1 had a highly malignant phenotype, including large tumor size, poor differentiation, impaired gluconeogenesis, and enhanced aerobic glycolysis. The effects of FBP1 expression on prognosis and glucose metabolism were confirmed by GSEA. Conclusion: Our findings established that FBP1 downregulation in HCC contributed to tumor progression and poor prognosis by altering glucose metabolism, and they rationalize further study of FBP1 as a prognostic biomarker and therapeutic target in HCC patients. Citation Format: Hiroaki Wakiyama, Hidenari Hirata, Keishi Sugimachi, Takaaki Masuda, Naoki Hayashi, Yohsuke Kuroda, Shuhei Ito, Hidetoshi Eguchi, Kotaro Terashima, Katsumi Sakamoto, Masakazu Hirakawa, Hiroshi Honda, Koshi Mimori. Loss of fructose-1,6-bisphosphatase expression induces altering glucose metabolism and tumor progression in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4411. doi:10.1158/1538-7445.AM2017-4411