Telomerase activity in pulmonary neuroendocrine tumors - Correlation with histologic subtype (MS-0060)

The authors measured telomerase activity using the telomeric repeat amplifi cation protocol-enzyme-linked immunosorbent assay method in 13 neuroendocri ne pulmonary neoplasms and in non-neoplastic frozen lung samples from the s ame patients. These cases belonged to the complete neuroendocrine neoplasti c spectrum: four typical carcinoids, three atypical carcinoids, four large cell neuroendocrine lung carcinomas, and two small cell lung carcinomas. Th e authors performed the same assay for 52 non-neoplastic lung tissues from the surgical files in their department (negative controls). They verified t he presence (or absence) of neoplastic tissue in every case by looking at o ne frozen section done in the same tissue used for telomerase assay. The te lomerase activity level in non-neoplastic tissues (mean, 182 A(450nm) U) wa s similar to that obtained in the typical carcinoids (mean, 104.5 A(450nm) U). All neuroendocrine tumors but the typical carcinoids showed high levels of telomerase activity (mean, 1,750.8 A(450nm) U). According to the telome rase hypothesis,typical carcinoid cells are mortal pre-M2 stage cells, but atypical carcinoid, large cell neuroendocrine lung carcinoma, and small cel l lung carcinoma cells are immortal post-M2 stage cells. This finding may b e of important prognostic significance in these kinds of tumors. Measuremen t of enzyme activity with good morphologic control could be necessary in te lomerase activity assay.