Identification of recurrent somatic mutation activating GP130 in inflammatory hepatocellular tumours reveals a new pathway of tumourigenesis in humans, according to researchers. This finding reinforces the role of inflammation in hepatocarcinogenesis and particularly in the malignant transformation of hepatocellular adenomas (HCA). Moreover, GP130 mutations will enable the refinement of the molecular classification of hepatocellular tumors in humans.
Inflammatory hepatocellular adenomas (IHCA) are benign liver tumours defined by the presence of inflammatory infiltrates and by an over-expression of inflammatory proteins. IHCA are usually developed in women and their occurrence is frequently associated with obesity and alcohol intake. Recently, somatic mutations were identified that activated GP130 in 60% of IHCA (Rebouissou et al, Nature, 2009), thus defining GP130 as a new oncogene in human tumours. This study aimed to evaluate frequency of GP130 mutations in a wide series of tumours.
Dr Jessica Zucman-Rossi of Inserm U674, Paris, France, who led the study, said: "This exciting advance means we now have a novel means of further investigating the development pathway of hepatocellular tumours as well as a new tool in the classification of hepatocellular tumours. It is an important step forward in our understanding of hepatocarcinogenesis and the future management of this disease."
Researchers in this study screened a series of 400 well-characterised hepatocellular tumours including hepatocellular adenomas, carcinomas, hepatocholangio-carcinoma, fibrolamellar carcinomas and intra-hepatic cholangiocarcinomas. 100 tumours from different organs were also collected. To search for mutations, GP130 exons were screened in all samples and the function of 7 different mutants was analysed in HEP3B.A somatic mutation was identified in 65% of the IHCA including 24 different small in-frame deletions or duplications. A spectrum of mutations shows that mutations clearly target the IL-6 binding site in GP130. Also demonstrated was the fact that the expression of the most frequent GP130 mutants in HEP3B cells activates STAT3 in absence of IL-6. The researchers searched for possible interaction and cooperation of GP130 activation with other pathways altered in hepatocellular adenoma. HNF1¥á inactivation and gp130 activation were mutually exclusive in HCA (P
*Somatic activating mutation of GP130 = the modification of only a few "coding letters" of the gp130 gene that leads to activation of the inflammatory response and escape of tumour hepatocytes from external control.
The International Liver Congress 2009, 44th Annual Meeting of the European Association for the Study of the Liver (EASL), is taking place in Copenhagen, Denmark, 22 April 2009. The official website is: http://www.easl.eu. Over 7,000 clinicians and scientists are expected to attend EASL 2009. Over the course of the Meeting, 144 oral presentations and 199 posters drawn from over 2179 abstract submissions will be featured.
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