APOPTOSIS IN HUMAN PITUITARY-ADENOMAS - A MORPHOLOGIC AND IN-SITU END-LABELING STUDY

Apoptosis seems to be an important process in normal tissues and in ne oplastic lesions. Although electron microscopic features of apoptosis are characteristic, it is difficult to detect apoptotic cells with acc uracy by light microscopy. Labeling of intranucleosomal DNA fragmentat ion can provide information on the apoptotic status of tumors, We stud ied apoptosis by the in situ end-labeling technique in 85 pituitary ad enomas (63 functioning, 22 nonfunctioning). The functioning tumors inc luded 19 somatotroph, 17 lactotroph, 9 mixed growth hormone/prolactin- producing, 2 thyrotroph, and 16 corticotroph adenomas, A few scattered cells displaying characteristic apoptotic changes were observed by hi stologic examination and electron microscopy. We estimated the apoptot ic labeling index (ALI) of the adenomas by quantitating the percentage s of positive nuclei. Overall, functioning adenomas showed a significa ntly higher ALI: (5.64%) than did nonfunctioning tumors (1.84%). The A LI was higher in thyrotroph adenomas (10.26%) and lower in corticotrop h (5.94%), somatotroph (5.51%), lactotroph (5.25%), and mixed growth h ormone/prolactin-producing adenomas (5.11%). In conclusion, in situ en d-labeling showed that apoptosis mostly occurs in functioning pituitar y adenomas, These data suggest that assessment of apoptosis can be use d to evaluate drug effects and to define which adenoma subtypes are mo re susceptible to drug therapy.