The main thing that makes cancer dangerous is its ability to spread around the body. Breast cancer is known to spread particularly to the bones.
Although tumours usually start in just one place, it is their ability to invade the surrounding tissues and spread to other parts of the body that makes then so very dangerous. Many types of tumour are known to particularly spread to the bones, although we do not understand the reason for this. If we could find a way to prevent cancers from spreading, it would make them much less dangerous.
AICR has funded the research of Dr John Price at the St Vincent's Institute of Medical Research in Australia, to study what makes breast cancer cells spread to the bones. He used two versions of a breast cancer cell line called 231. The 231high cells showed a very high level of spread to the bones whilst the 231low cells showed a very low level.
Their genes control all the activities of cells, so Dr Price compared the activity of the genes between these two cell types. This revealed about twenty genes that had differences in their activity. One of these genes was called HSP90b and almost all the other genes were known to be associated with HSP90b, which strongly suggested that HSP90b was a crucial gene involved in causing breast cancer cells to spread to the bones. To study this further, Dr Price examined a number of samples of breast cancers that had spread into the breastbone. All of these samples were found to have high levels of the protein produced by the HSP90b gene.
Further supporting evidence came when Dr Price studied the effect of a new drug called 17-AAG which blocks the activity of the HSP90b protein. Interestingly, he found that this drug increased the activity of the HSP90b gene and this resulted in an increase in the spread of the 231 breast cancer cells to the bones.
This research clearly implicates the HSP90b gene in causing the spread of breast cancer cells to the bones. This finding has opened the door to the development of drugs to block the activity of this gene which may well prevent the spread of breast cancer.
