Gene expression profiling of colon cancer by correlation with ¹⁸F-FDG kinetics as measured by dynamic positron emission tomography-computed tomography (dPET-CT)

Objectives The kinetics of ¹⁸F-FDG as measured by dPET is determined by glucose transporters and hexokinases, and may be modulated by other genes. The dependency of ¹⁸F-FDG kinetics on hypoxia- and cadherin-related gene expression was evaluated in this study.

Methods Patients with colorectal tumors (n=17) were examined with ¹⁸F-FDG dPET-CT. Tissue specimens were obtained from the tumor and the normal colon during surgery, and gene expression was assessed using gene arrays (Affymetrix U133 plus 2.0). The dynamic PET-CT data were evaluated based on a 2-tissue compartment model.

Results Overall, 13 hypoxia- and cadherin-related gene expression were identified with a tumor-to-normal ratio exceeding 2.0. Analysis revealed a significantly negative correlation between ki and hypoxia-inducible protein 2 (HIG2) (r=-0.52). A correlation was obtained for the cadherin-related CDH3, CDH7, CDH13, PCDHGB7, PCDHGC3, PCDHB17, PCDHGC5 and K1.

Conclusions The transport rate for ¹⁸F-FDG (K1) is higher in tumors with a high expression of cadherin-related genes. The parameters of ¹⁸F-FDG dPET kinetics can be used to predict the expression of cadherin associated genes individually, which are important for cell adhesion. Therefore, a prediction of cadherin expression may help to individually predict therapeutic outcome noninvasively.