RT‐PCR detection of fibronectin EDA+ and EDB+ mRNA isoforms: Molecular markers for hepatocellular carcinoma

Alternative splicing of fibronectin pre‐mRNA has been shown to be independently regulated at the EDA and EOB regions in a tissue and developmental stage‐specific manner. In this study, RT‐PCR approaches were developed for the detection of EDA and EDB FN mRNA isoforms in hepatocarcinoma cells (SK‐Hep‐I) grown in vitro and in human liver biopsies. While EDA+ and EDB+ isoforms were not present in control adult liver, they were detectable in the hepatocarcinoma cells and in fetal liver. The RT‐PCR analysis, extended to biopsies of malignant and non‐malignant hepatic tissues, showed that FN mRNAs containing the EDA and EDB sequences were present in the 14 hepatocelfular carcinomas (HCCs) tested but absent in the non‐tumorous liver tissues (i.e., normal parenchyma, nonspecific reactive and chronic hepatitis, steatosis). The EDB+ FN mRNA isoforms were also detected in 3 cases of benign neoplasm (hepatocellular adenoma, HCA, I; nodular focal hyperplasia, NFH, 2), while the EDA+ was only detectable in I of the 2 cases of NFH. In addition, both EDA+ and EDB+ isoforms were expressed in 5 out of 9 cirrhotic livers surrounding the tumors. This molecular analysis, which can also be performed on small liver biopsies (2 mg), may therefore be a useful additional tool in the diagnosis of HCC.