In patients with suspected metastatic cancer in the brain, a useful diagnostic is positron emission tomography, PET. This technique utilizes a radioactive form of glucose that cannot be metabolized but is rapidly taken up by cancer cells due to their high rates of metabolism. Which of the following is most responsible for the rapid uptake of this compound into the tumor cells in the brain?

Question

Quizplus · Accepted Answer

GLUT3 is a glucose transporter that is highly expressed in neurons and has a high affinity for glucose, facilitating the rapid uptake of glucose into cells, including tumor cells in the brain.  When glucose is taken into cells, it is phosphorylated by one of the various hexokinases (called glucokinase in liver and pancreas), which trap it within the cell. Using a nonmetabolizable form of glucose that is tagged with a radioisotope allows for detection within cells via PET. Uptake of glucose into cells occurs via facilitated diffusion with one of several glucose transporters termed GLUTs. Within the brain, GLUT3 is the principal glucose transporter.

In Patients with Suspected Metastatic Cancer in the Brain, a Useful