Protein sheds light on higher liver cancer rates in men
A protein that promotes inflammation may be linked to the higher rates of liver cancer in men than women, according to new research.
Hepatocellular carcinoma (HCC), which accounts for the majority of liver cancers in humans, is three to five times more likely to occur in men than women.
In an attempt to discover the reasons for this difference, researchers at the University of California, San Diego (UCSD) School of Medicine conducted a small-scale study in mice.
The study, published in the journal Science, focused on a protein called interleukin (IL-6), which contributes to the chronic liver inflammation believed by some researchers to lead to cancer development.
The researchers, led by Dr Michael Karin, professor of pharmacology in UCSD's Laboratory of Gene Regulation and Signal Transduction, used a cancer-causing chemical called 'DEN' to induce liver cancer in mice, resulting in all of the male mice, but just ten to 20 per cent of female mice, developing cancer.
Female mice were found to produce far less IL-6 than the males, and eliminating IL-6 in male mice reduced the incidence of liver cancer by nearly 90 per cent, Dr Karin revealed.
The researchers then treated male mice with oestrogen and found that the oestrogen blocked production of the IL-6 protein, decreasing both their IL-6 levels and the degree of liver injury to the same level as female mice.
They suggest that a similar mechanism may be responsible for the higher incidence of liver cancer in male humans than females and suggest that reducing the levels of IL-6 in males, interfering with the protein's action, or administering oestrogen-like compounds to inhibit its production may lead to new liver cancer therapies.
Study author Willscott Naugler, clinical instructor in UCSD's department of medicine, commented: "While some organs, such as breasts, are clearly influenced by gender, others - like the liver - are not.
"So it's quite interesting that liver inflammation is so markedly suppressed by oestrogens," he continued.
"It raises the possibility that organs not usually associated with gender differences may be governed by the same principle. Bladder cancer, for example, occurs more frequently in males than females, and the differences may be a result of higher IL-6 levels and inflammation in male bladders."