Somatostatin receptors in resected hepatocellular carcinoma: status and correlation with markers of poor prognosis

Aims: To investigate the status of somatostatin receptors (SSTRs) in resected hepatocellular carcinoma (HCC). Methods and results: Transcript and protein levels of SSTR2, SSTR3 and SSTR5 were investigated, with real-time polymerase chain reaction (PCR) and manual and automated immunohistochemistry (IHC), in 53 resected HCCs and paired non-tumour tissues. SSTR1, SSTR4, SSTR5TMD4 and SSTR5TMD5 were analysed with real-time PCR. SSTR3 and SSTR5 transcripts were expressed in similar to 25% of HCCs, but not in adjacent non-tumour tissues. SSTR1 and SSTR2 transcripts were overexpressed in 42% and 32% of HCCs, respectively. SSTR4, SSTR5TMD4 and SSTR5TMD5 were not detected. Membrane staining for SSTR2 was detected in 38% of HCCs, whereas SSTR5 protein was detectable in only 11% of HCCs. SSTR3 protein was detected in the majority of HCCs and adjacent non-tumour liver tissues, but membrane staining was <20% of that in HCCs. The results obtained with the two IHC methods were highly correlated (P < 0.0001). Statistical analyses also showed a positive correlation between SSTR2 membrane staining and cytokeratin 19 expression (P = 0.04), serum a-fetoprotein level (P = 0.002), and poor differentiation (P = 0.05). Conclusions: Membrane SSTR2 is detected reliably in HCCs by IHC, and is a potential therapeutic target, as it is coexpressed with markers of poor prognosis.