last updated April 2013
Energizing cancer cells
A newly identified signaling pathway controls the rate of glucose consumption in breast cancer cells
Normal cells rely mainly on a process called oxidative phosphorylation to generate energy from glucose; however, most cancer cells metabolize glucose by a process called aerobic glycolysis. This is regulated by inflammation, a key factor that promotes tumor growth, but exactly how was unclear. Now, a research team led by Mo-Fang Liu of the Chinese Academy of Sciences has discovered the signaling pathway that controls energy consumption in breast cancer cells1.
Liu and her colleagues examined how the inflammatory mediator interleukin-6 (IL-6) affects breast cancer cells. They found that it increased the rate of glycolysis, as did several other related molecules. By examining the effects of miR-155, a microRNA they had previously linked to inflammation and cancer2, they discovered that miR-155 overexpression in breast cancer cells also increased glycolysis, whereas inhibiting its expression reduced it.
The researchers also showed that IL-6 and miR-155 increase expression of several key glycolysis genes, particularly the gene encoding hexokinase 2, the enzyme that catalyzes the first step of glycolysis. This occurs via two distinct mechanisms — by activating STAT3, which initiates hexokinase expression, and inhibiting C/EBPß, which represses hexokinase expression by activating transcription of another microRNA.
“We’re screening miRNAs involved in inflammation-associated tumor formation,” says Liu, “and exploring miRNA-based approaches for cancer therapy and prevention.”