Telomerase activity and the expression of telomerase components in pituitary adenoma with malignant transformation

Telomerase activity responsible for cellular immortality may participate the development of human cancers. Telomerase is a multisubunit ribonucleoprotein composed of at least three components: hTERT, hTERC, and TEP1. This is the first report showing telomerase activity and telomerase component expression in pituitary adenoma with histological malignant transformation.

A 16-year-old male with a prolactin-producing pituitary adenoma with metastasis is presented. The patient underwent three partial resections of an intra- and suprasellar lesion over a 2-year period and received focal irradiation. Eight years after the first admission, a metastatic lesion to the subarachnoid space around the medulla oblongata was detected and the lesion was resected as the fourth operation. Furthermore, the suprasellar lesion showed regrowth and partial resection was performed as the fifth operation. The last two specimens were diagnosed as pituitary carcinoma. Radiotherapy with gamma knife was performed for the residual suprasellar lesion and a new lesion in the left temporal lobe after the fifth operation. Telomerase activity was examined by TRAP/TRAP-HPA methods, qualitatively and quantitatively. Telomere length was examined by Southern blot analysis, and the expression of telomerase components (hTERT, hTERC, and TEP1) was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). The MIB1 index, telomerase activity, and hTERT expression increased according to histologic malignancy chronologically in this patient. None of the specimens showed immunoreactivity for p53, EGFR, or bc12. No telomerase activity was detected in pituitary adenomas without malignant transformation, other benign brain tumors, or normal brain tissues.

We report a patient with pituitary adenoma transforming to carcinoma. The tumor cells acquired immortality and revealed malignant transformation during the course of the disease, that was proved by an increase of telomerase activity and hTERT expression.