Μελέτη της έκφρασης του E2F-1 και του CD138 στη χρόνια ηπατική νόσο και το ηπατοκυτταρικό καρκίνωμα

Abstract

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer andusually develops in a background of chronic liver disease. During the multistageprocess of human hepatocarcinogenesis many molecular pathways are disrupted. Thisstudy examines two aspects of hepatocarcinogenesis:a) E2F-1 immunoexpression in chronic viral hepatitis and HCCIntroduction: Transcription factor E2F-1 induces expression of genes governing G1/Sphase transition, DNA synthesis and repair, and apoptosis. Hyposphorylated pRbrepresses E2F-1 action in early G1 phase, while in late G1, pRb hyperphosphorylationleads to E2F-1 release and activation. In vitro studies have shown that E2F-1 may acteither as oncogene or as tumor suppressor gene. To the best of our knowledge, theexpression of E2F-1 in human chronic viral liver disease and HCC, and its role -oncogenic or tumor suppressing - in HCC have not been elucidated to date.Material and Methods: We evaluated by immunohistochemistry E2F-1 expression inliver biopsies from 30 chronic viral hepatitis B or C (22 with cirrhosis ) patients and57 patients with HCC of viral etiology. Results were correlated with clinicopathologicalparameters, cell proliferation (Ki67 labelling index-LI) and apoptosismarkers (M30 apoptotic index), as well as with the immunoexpression of pRB andphosphoSer795pRB.Results: In chronic hepatitis and cirrhosis, hepatocytes and cholangiocytesdemonstrated mild cytoplasmic and/or nuclear membrane E2F-1 immunostaining. AllHCCs (100%) showed strong nuclear E2F-1 immunostaining, with or withoutmembrane accentuation, while 16% demonstrated additional moderate cytoplasmicimmunostaining. Abnormal pRb and phospho-pRb expression was seen in 70% and67.9% of HCC, respectively. In HCC, E2F-1 LI was inversely correlated withphospho-pRb LI (p=0.001) and positively related to tumor apoptotic index (p=0.025).No significant correlation was found between E2F-1 expression and clinicμ-pathological parameters, as well as with pRb and Ki 67 LI (p>0.05).Conclusions: In all cases of HCC, E2F-1 is overexpressed compared to chronichepatitis and cirrhosis. E2F-1‟s nuclear immunoreactivity in combination withabnormal immunoexpression of its regulatory proteins, Rb and phospho-pRb,indicates that it is transcriptionally active in the majority of HCC. E2F-1 expressionis correlated with enhanced tumor cell apoptosis supporting a possible pro-apoptoticrole of E2F-1 in human HCC. b) CD138 immunoexpression in HCCIntroduction CD138 (syndecan-1) is a proteoglycan that regulates cell-cell and cellmatrixinteractions. CD138 is predominantly expressed in epithelial cells andplasmacytes. CD138 expression is dysregulated in cancer and has been proposed as aprognostic marker in many types of cancer. Limited data is available regarding itsexpression in HCC while its prognostic significance has not been assessed to date.Material and Methods: CD138 was semiquantitatively evaluated on 58 histologicalsections from 45 hepatectomy specimens of HCC. CD138 immunoexpression wascorrelated with clinico-pathological parameters, patients‟ overall survival data, as wellas with the expression of HepPar-1, an established immunomarker for HCC diagnosisResults: CD138 immunostaining was detected in all HCC (100%), with membranousand/or cytoplasmic immunolocalisation, irrespective of tumor grade, in contrast toHepPar-1 that was negative in 18.9% of HCCs, more frequently of high grade(p=0.008). CD138-positive membranous immunostaining was inversely correlatedwith tumor grade (p=0.005) but did not correlate with patients‟ survival. On thecontrary, intense cytoplasmic CD138 immunoepxression proved to be an independentmarker of poor prognosis (Cox backward stepwise regression analysis, p=0.049).Conclusions: CD138 proteoglycan is expressed in all HCC, in contrast to HepPar-1,indicating CD138‟s higher sensitivity for HCC diagnosis. In human HCC, reductionof membranous CD138 immunoreactivity may be related to tumor dedifferentiation,while increased cytoplasmic CD138 immunoexpression may serve as a marker ofpoor prognosis in HCC.E2F-1 transcription factor and CD138 proteoglycan are elements of a wide network ofinteracting molecules that compose the complex “hepatocarcinogenesis scenery”. Indepth study of E2F-1‟s possible oncosuppressive activity in HCC - that wassuggested in the present thesis - may lead to the development of newchemotherapeutic agents for treating this lethal cancer. Validation of the prognosticsignificance of CD138 immunoexpression - highlighted herein - in larger studies ofhuman HCC may contribute to the personalized therapy of HCC patients.