Previous studies have shown that by knocking out the GSTP gene in mice, exposure to environmental chemicals including cigarette smoke increases the incidence of lung and skin cancer. Now, the team at Dundee University have shown that the absence of GSTP in mice prone to cancer of the small intestine, led to a 50-fold increase in the development of tumours located in the same region that human bowel cancers are found.
'These data provide fascinating new insights into a gene which can affect the development of bowel cancer, possibly by affecting inflammatory responses', said lead author of the study, Professor Roland Wolf, from the Biomedical Research Institute at the University of Dundee. The results of the study, published in the journal Proceedings of the National Academy of Sciences, show that there was more inflammation present in the bowels of mice which had had the GSTP gene removed. Inflammation has already been shown to lead to the development of polyps, which can go on to become cancerous, and this is where the researchers believe the gene plays a protective role.
'We are beginning to realise that inflammatory responses are very important - both in terms of a predisposition to cancer but also how you respond to treatment', said Dr Rob Glynne Jones, the chief medical adviser at the charity Bowel Cancer UK. 'We are in the process of unravelling the story, and a study like this is another piece of the jigsaw. Anything we can find out about possible causes helps us at every level - and what this looks like here is another potential pathway to disease', he said.
Bowel cancer is the third most common cancer in the UK, and diet is known to have a big impact on its development. The implications of the GSTP study are that certain foods such as broccoli, may contain chemicals which naturally boost GSTP levels in the body. 'We know a diet with lots of red and processed meat will increase the chances of developing bowel cancer whereas a fibre-rich diet reduces the risk', said Dr Lesley Walker, Cancer Research UK's director of cancer information. If the link between certain foods and GSTP can be proven in humans, 'it could suggest another way of reducing the risk of bowel cancer,' said Dr Walker.