SCIENTISTS have made a discovery which they hope will lead to new treatments for the progressive wasting which causes the deaths of thousands of cancer patients.
A new study suggests proliferating cancer cells actively cause the body to starve by simulating an effect of diabetes.
The research, conducted on fruit flies, points towards potential new treatments for cachexia - the wasting that accompanies advanced cancers.
Around a fifth of cancer deaths are due to cachexia, which can render patients too weak to withstand chemotherapy and radiotherapy and increase their susceptibility to side effects.
Typically raising food intake does little to stem the loss of muscle and fat.
Scientists in the US now believe tumour cells actively secrete proteins that inhibit insulin, the hormone responsible for energy-giving glucose being absorbed into the body tissues.
In this way more of the sugar is made available to satisfy the cancer's enormous appetite for glucose.
People with diabetes either lack insulin or fail to respond to it, so that their tissues are also prevented from absorbing glucose.
Researcher Dr Young Kwon, from Harvard Medical School in the US, said: "The findings suggest that the proliferating tumour cells consume a lion's share of glucose for energy, while the rest of the body progressively starves."
Clues to the process emerged from two studies of cachexia in fruit flies with cancer. Tumours in the insects secreted a molecule called ImpL2 that triggered the loss of fat and muscle tissue, replicating cancer-induced wasting in humans.
ImpL2 is the fly version of mammalian insulin growth factor binding proteins (IGFBPs) which inhibit the activity of insulin in humans and other mammals.
Lowering ImpL2 levels in the flies significantly reduced wasting, suggesting that targeting its molecular twin in humans might provide a way of treating cachexia.
A key question is how growing tumours evade the effects of insulin-suppression, which might be expected to cut off their supplies of glucose as well.
The answer could be linked to differences in insulin signalling and glucose metabolism that shield the cancer from starvation, the research suggests.
Dr David Bilder, from the University of California at Berkeley, who led one of the studies published in Developmental Cell, said: "Many cancer patients die not because of the local effects of tumours, but rather from more broad, systemic changes to the entire body that are induced by these tumours.
"One of the worst of these long-range effects is wasting syndrome, also known as cachexia, which is a major obstacle to cancer treatment.
"The two new studies illustrate the power of using simple model organisms to provide new insights relevant to the most important questions of human cancer biology."
Depletion of ImpL2 did not fully reverse tissue loss in the flies, indicating that other unknown factors are also involved.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article