Regulation of 18F-FDG Accumulation in Colorectal Cancer Cells with Mutated KRAS

Journal of Nuclear Medicine

Kosuke Toda¹  Yoshiro Itatani¹  Suguru Hasegawa¹  Susumu Inamoto¹  Hiroyuki Kimura¹  Kaori Togashi¹  Masayoshi Iwamoto¹  Yoshiharu Sakai¹  Hiroaki Okuyama¹  Kenji Kawada¹  Masahiro Inoue¹  Senji Shirasawa¹  Takehiko Sasazuki¹  Yuji Nakamoto¹ 

关键词: colon cancer;    KRAS;    ¹⁸F-FDG PET scans;    imagingglucose metabolism;   

DOI  :  10.2967/jnumed.114.142927

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

KRAS gene mutations occur in approximately 40% of colorectal cancers (CRCs) and are associated with resistance to anti–epidermal growth factor receptor antibody therapy. We previously demonstrated that 18F-FDG accumulation in PET was significantly higher in CRCs with mutated KRAS than in those with wild-type KRAS in a clinical setting. Here, we investigated the mechanisms by which mutated KRAS increased 18F-FDG accumulation. Methods: Using paired isogenic human CRC cell lines that differ only in the mutational status of the KRAS gene, we measured 18F-FDG accumulation in these cells in vitro and in vivo. We also investigated the roles of proteins that have a function in 18F-FDG accumulation. Finally, we examined the relationship among mutated KRAS, hypoxia-inducible factor 1α (HIF-1α), and maximum standardized uptake value with 51 clinical CRC samples. Results: In the in vitro experiments, 18F-FDG accumulation was significantly higher in KRAS-mutant cells than in wild-type controls under normoxic conditions. The expression levels of glucose transporter 1 (GLUT1) and hexokinase type 2 (HK2) were higher in KRAS-mutant cells, and 18F-FDG accumulation was decreased by knockdown of GLUT1. Hypoxic induction of HIF-1α was higher in KRAS-mutant cells than in wild-type controls; in turn, elevated HIF-1α resulted in higher GLUT1 expression and 18F-FDG accumulation. In addition, HIF-1α knockdown decreased 18F-FDG accumulation under hypoxic conditions only in the KRAS-mutant cells. Small-animal PET scans showed in vivo 18F-FDG accumulation to be significantly higher in xenografts with mutated KRAS than in those with wild-type KRAS. The immunohistochemistry of these xenograft tumors showed that staining of GLUT1 was consistent with that of HIF-1α and pimonidazole. In a retrospective analysis of clinical samples, KRAS mutation exhibited a significantly positive correlation with expressions of GLUT1 and HIF-1α and with maximum standardized uptake value. Conclusion: Mutated KRAS caused higher 18F-FDG accumulation possibly by upregulation of GLUT1; moreover, HIF-1α additively increased 18F-FDG accumulation in hypoxic lesions. 18F-FDG PET might be useful for predicting the KRAS status noninvasively.

【 授权许可】

Unknown