Significance of absent prohormone convertase 1/3 in inducing clinically silent corticotroph pituitary adenoma of subtype I--immunohistochemical study.
Biologically inactive ACTH-producing pituitary adenoma is known as clinically silent corticotroph adenoma. To search for the mechanism causing clinically silent corticotroph adenoma, we immunohistochemically examined the expression of prohormone convertase 1/3 (PC1/3) in this type of adenoma and compared our results with those obtained for Cushing's disease. All of the Cushing's disease specimens exhibited strongly positive PC1/3 exhibition. On the contrary, the expression of PC1/3 was very weak in the clinically silent corticotroph adenoma specimens. The absence of PC1/3 in clinically silent corticotroph adenoma indicates that silent corticotroph adenomas arise in a different cell type sharing the prohormone pro-opiomelanocortin (POMC), but processing it differently, accounting for the lack of clinical symptoms due to ACTH excess.
Ohta
S
S
Department of Neurosurgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.
Nishizawa
S
S
Oki
Y
Y
Yokoyama
T
T
Namba
H
H
D000236:Adenoma / Q000201:enzymology* / Q000235:genetics*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000368:Aged; D003480:Cushing Syndrome / Q000201:enzymology / Q000235:genetics; D005260:Female; D045683:Furin; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000201:enzymology* / Q000235:genetics*; D011333:Pro-Opiomelanocortin / Q000378:metabolism; D013381:Subtilisins / Q000235:genetics*
D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone; D013381:Subtilisins; D045683:Furin; D006854:Hydrocortisone