Fly with brain tumor may shed light on cancer causing genes

A study showing how the expression of genes changes when the brain tissue of fruit flies becomes cancerous is published this week in BMC Genomics. As the function of many of these genes is conserved across evolution, the researchers expect their results will help us to understand why human brain tumors develop.

The causes of brain tumor development are largely unknown. To investigate this question, researchers from University of Basel, Switzerland and University of Freiburg, Germany, used microarray technology to compare the levels of gene expression in the heads of healthy flies and those with brain cancer.

They found significant changes in the expression levels of 321 different genes. These were involved in several different processes including metabolism, cell proliferation, gene transcription and protein translation.

“One fifth of these genes show homology to known mammalian genes involved in cancer formation,” write the researchers.

The flies with cancer had mutations in the tumor-suppressor gene brain tumor (brat), which stopped the gene from functioning correctly. Inactivation of the brat gene causes the Drosophila larval brain to overgrow. The majority of larvae do not make it to adulthood – only 15% of them turn into flies. Surviving flies have large brains made up of cancerous tissue, and they normally die young.

If cells from this cancerous tissue are transplanted into a healthy fly, they grow rapidly and spread – forming secondary tumors around the fly’s body. The researchers plan to use the information that they have gathered from this experiment to elucidate which of the genes upregulated in these cancer cells are responsible for the cells’ metastatic behaviour.