Abstract 2716: Oncogenic K-ras mutation associates with GLUT1 expression in mice and human colorectal cancer.

Abstract

Abstract Background and aims: Somatic APC defects are present in 75% of sporadic colorectal cancer. K-ras gene mutations found in 40-50%, occur early in the progression to carcinoma, but their functional contribution remains incompletely understood. Previous study reported that GLUT1, encoding glucose transporter-1, was one of the genes consistently up-regulated in colorectal cancer cell lines with K-RAS or BRAF mutations. In this study, we have analyzed tumors from genetically modified mice carrying either mutation in the Apc gene or in combination with another mutation in the K-ras G12D allele. Subsequently, we evaluated whether K-RAS gene mutations associate GLUT1 expression in human colorectal cancer. Methods: Mice carrying transgenes regulated by CDX2 homeobox gene promoter (CDX2P9.5) showed tightly restricted transgene expression in the colon in adult tissues. Cre recombinase transgenes with 22 guanine nucleotides (G22Cre) introduced downstream of the initiating ATG codon, and CDX2P9.5-G22Cre transgenic mice homozygous for the Apc flox allele lived only for 10-27 d after birth due to the tumor in the proximal colon. Mice carrying loxP-flanked Apc alleles homozygously (ApcloxP/loxP, 580S) were intercrossed with Lox-Stop-Lox K-ras conditional mice strain (referred to as LSL-K-ras G12D) to generate CDX2P9.5-G22Cre;Apcflox/flox;LSL-K-ras G12D with K-ras G12D expression (CPC;Apc 580D;Lox-K-ras G12D). Gene expression analyses on the 3 samples from CPC;Apc 580D;Lox-K-ras G12D mice and CPC;Apc 580D;K-ras WT mice were performed with high-density oligonucleotide arrays (GeneChip Mouse Genome 430 2.0 Array). Results: Glut1 was found to be up-regulated significantly in CPC;Apc 580D;Lox-K-ras G12D mice. Immunohistochemical staining revealed that Glut1 protein was up-regulated in CPC;Apc 580D;Lox-K-ras G12D mice. 47 samples of colorectal cancer patients with K-RAS mutations in 18 patients (38.3%) showed GLUT1 expression in 12 patients of 18 K-RAS mutated patients and 8 patients of 29 K-RAS wild-type patients. Conclusions: Using mice carrying conditional solely mutant in the Apc gene or in combination with the K-ras G12D allele, we assessed the relevance of oncogenic K-ras with Glut1 in colorectal cancer. Microarray analysis, quantitative PCR, and immunohistochemistry suggested the association of the K-ras with the Glut1 (Glut1). Our clinical analysis showed K-RAS gene mutations significantly associate GLUT1 expression in human colorectal cancer. Citation Format: Yasuo Kawaguchi, Takao Hinoi, Tatsunari Sasada, Tomohiro Adachi, Yasufumi Saito, Shinji Miguchi, Hiroaki Niitsu, Hideki Ohdan. Oncogenic K-ras mutation associates with GLUT1 expression in mice and human colorectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2716. doi:10.1158/1538-7445.AM2013-2716