SEC62 and SEC63 Expression in Hepatocellular Carcinoma and Tumor-Surrounding Liver Tissue

Abstract

Introduction: The endoplasmic reticulum transmembrane proteins Sec61, Sec62, and Sec63 are responsible for the intracellular trafficking of precursor proteins and affect intracellular signaling. SEC62 overexpression has been linked to various human cancers. Our aim was to investigate SEC62 and SEC63 expression in hepatocellular carcinoma (HCC) and surrounding liver tissue. Patients and Methods: Primary liver tissue was collected from 11 consecutive patients (70 ± 9 years; 10 men) who underwent HCC resection. In the HCC and the tumor-surrounding liver tissue we investigated SEC62 und SEC63 mRNA expression using quantitative real-time PCR. For Sec62, immunohistochemistry was performed. Results: SEC62and SEC63 total mRNA contents were significantly (p = 0.001) higher in HCCs (CT 22.5 ± 0.4 and 22.6 ± 0.3) when compared to the surrounding tissue (CT 24.6 ± 0.6 and 25.1 ± 0.9). Using the comparative CTmethod, SEC62 and SEC63 expression in HCC was increased 5- and 8.1-fold, respectively, in comparison to surrounding tissue. For Sec62 immunohistochemistry, the mean immunoreactive scores (IRS) were 7.9 ± 2.9 for HCC and 4.8 ± 1.2 for non-tumorous liver (p = 0.027). The mean IRS in HCC were 5.7 ± 3.5 and 8.9 ± 2.3 for patients without (n = 3) and with tumor recurrence (n = 8), respectively. Conclusions: Overexpression of SEC62 and SEC63 is a common feature of HCC. The role of Sec62 as a prognostic marker for tumor recurrence after surgery and its potential role in treatment stratification must be addressed in future studies.