Paving the way for developing highly specific cancer drugs with fewer side-effects, researchers have discovered that cancer cells and normal cells use different 'gene switches' in order to regulate the expression of genes that control growth.

"Since we find that the growth of normal and cancer cells is driven by different gene switches, we can in principle aim at switching off the system for growth only in the cancer cells without any harmful effect on the growth of normal cells," said lead researcher Jussi Taipale, Professor at Karolinska Institutet in Sweden."This can lead to the development of highly specific approaches for cancer therapy with much lower toxic side effects," Taipale added.In mice, the removal of a large regulatory region linked to different types of cancer caused a dramatic resistance to tumour formation, but did not affect normal cell growth, according to the findings published in the journal eLife.

Using mice, the scientists analysed a large gene switch region that is linked to the risks of developing many different types of cancer, including prostate, breast, colon, bladder and thyroid cancers as well as chronic lymphocytic leukaemia and myeloma.The variation in this region accounts for far more cancer-related deaths than inherited mutations in well-known cancer-causing genes. The scientists turned the gene switches off by removing this region from the mouse genome, and found that its loss has no effect on normal mouse development and growth. 

Although removing the gene switch region brought down the levels of the nearby cancer gene Myc, the mice remained normal and healthy. The mice were strongly resistant to the formation of breast tumours and tumours in the intestine, the study said.According to the scientists, these results show that normal cells can function and divide without the genetic elements that are needed for the growth of cancer cells.