Quantitation of somatostatin receptor type 2 in neuroendocrine (merkel cell) carcinoma of the skin by competitive RT-PCR

Abstract

Merkel cell neuroendocrine carcinoma (MCC) is a rare but highly aggressive small-cell tumor affecting the skin and, rarely, the lymph nodes (in the absence of a primary site). MCC expresses several neuroendocrine markers, but no data are available on the presence of somatostatin receptors (SSTR) in this tumor. SSTR type 2, mostly detected in normal and neoplastic nervous and neuroendocrine cells, bind the somatostatin analog octreotide with the highest affinity. The aim of this study was to investigate the presence of SSTR2 mRNA in MCC, to quantitate their occurrence in individual tumors, and to correlate the presence of SSTR2s with tumor progression and outcome. SSTR2 mRNA was present in 9/10 cases of primary or metastatic MCC by reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot. A variable amount of receptors was found, spanning at least two log units (106–108 mol/μg RNA). Presence of SSTR2 was not correlated with clinical parameters or evolution. It is concluded that MCC shares the property of other neuroendocrine tumors of expressing SSTR2; in a subset of MCC, endowed with high amounts of SSTR2 Octreotide may be an adjunct in the therapeutic strategy for these tumors.