CALCITONIN GENES (I AND II) EXPRESSION IN HUMAN NERVOUS AND MEDULLARY-THYROID CARCINOMA TISSUES

The calcitonin gene family comprises two main genes: CALC I which enco des for calcitonin (CT) mRNA in thyroid and calcitonin gene-related pe ptide I (CGRP I) mRNA in neuronal tissues and CALC II gene which encod es for CGRP II mRNA only. Recently, in normal thyroid and in medullary thyroid carcinoma (MTC), we detected an additional splicing pathway i nvolving the splicing of exon 4 to exon 5 and leading to the expressio n of a third CALC I mRNA: CT mRNA II. In the present study, we analyze d by polymerase chain reaction the expression of CT mRNAs I and II, CG RP I and II mRNAs in MTC and in human tumors of the nervous system (3 pituitary adenomas, 3 astrocytomas, 2 schwanomas). In pituitary tissue s, CGRP II expression was constant and easily detectable in comparison to other tissues. CT mRNA II signal was very low, but clearly detecta ble after a reamplification indicating that the factors responsible fo r the splicing of exon 4 to exon 5 are poorly operative in neuronal ti ssues.