Hepatocellular carcinoma and estrogen receptors: Polymorphisms and isoforms relations and implications

Hepatocellular carcinoma (HCC) is the most common primary tumor of liver and its incidence continues to increase worldwide. HCC is a disease with multifactorial causes and genetic variability has been discussed as a risk factor for its development. Liver is a hormone-sensitive organ and therefore is influenced by gonadal hormones, such as estrogen. Estrogen is known to participate in various biological functions, but its role in development of HCC, on the other hand, is controversial and presents evidence suggesting a role as both a carcinogen and protective effect in liver. Estrogen way of action is mediated by estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), that belong to a family of nuclear receptors that may regulate the expression of many genes. The ER subtypes exert a variety of roles in many stages of liver disease and may play a part in the process of signal transduction, according to some studies. However, the many functions of ER subtypes in hepatic diseases, in special of the ERβ, are yet to be clarified. The genetic modifications related to HCC are not yet fully clarified and accumulation of multiple genetic alterations appears to have an important role in carcinogenesis of HCC. The presence of some certain single nucleotide polymorphism (SNP) may have a functional repercussion related to final product of a gene, which can be measured and may participate in some alterations related to a pathological condition. Our hypothesis is based on the fact that liver tissue express ER and its different variants exert multiple functions in various stages of liver disease and participate in an extremely complicated signal transduction process, therefore we believe that the presence of one or more SNPs of ESR1 and ESR2 genes may be related with the increase of risk in developing and the severity of HCC, as well as in the response to different treatments. The confirmation of our hypothesis by scientific studies may provide knowledge of markers that act as prognostic factors of this disease, as well as enabling alternatives to development of anti tumoral therapies.