Expression patterns of messenger ribonucleic acids encoding prohormone convertases (PC2 and PC3) in human pituitary adenomas.
OBJECTIVE
Prohormone convertases (PC2 and PC3) have been reported to play an important role for prohormone processing in rodent pituitaries. However, expression of mRNAs encoding these enzymes has not been characterized in human pituitaries. In addition, altered or insufficient prohormone processing has been reported in some human pituitary adenomas. Thus, the expression patterns of these mRNAs in non-tumorous and tumorous human pituitaries should be examined.


METHODS
Total RNAs were extracted from non-tumorous or tumorous human pituitaries to analyse PC2 and PC3 mRNA expression.


METHODS
Five ACTH producing adenomas, 11 GH producing adenomas, one PRL producing adenoma and five non-functioning adenomas were obtained at surgery. Two non-tumorous pituitaries were also included in this study.


METHODS
The contents were quantitatively measured by Northern blot analysis using rat PC3 cDNA or human PC2 cDNA as a probe. The method was also developed for the detection of PC2 mRNA by Southern blot analysis of reverse transcriptase-polymerase chain reaction (RT-PCR) products.


RESULTS
PC2 and PC3 mRNAs in non-tumorous samples were detected by Northern blot analysis whereas their contents in tumorous samples varied from high levels to undetectable. Marked variation of PC3 mRNA levels was observed among GH producing adenomas. ACTH producing adenomas were observed to express PC3 mRNA. Northern blot analysis also revealed that PC2 mRNA levels in ACTH producing adenomas were low except for one sample. PC2 mRNA expression in GH producing adenomas was confirmed by Southern blot analysis of RT-PCR products. This procedure also confirmed the various levels of PC2 mRNA expression among ACTH producing adenomas.


CONCLUSIONS
The expression of PC2 and PC3 mRNA in human pituitaries has been confirmed. However, their expression has been observed to vary quantitatively and not to be restricted to certain types of pituitary cells.
Hashimoto
K
K
Department of Medicine III, Osaka University Hospital, Suita-shi, Japan.
Koga
M
M
Kouhara
H
H
Arita
N
N
Hayakawa
T
T
Kishimoto
T
T
Sato
B
B
D000236:Adenoma / Q000201:enzymology*; D000328:Adult; D016282:Aspartic Acid Endopeptidases / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D017931:DNA Primers; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000201:enzymology*; D010911:Pituitary Neoplasms / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D045706:Proprotein Convertase 2; D043484:Proprotein Convertases; D012333:RNA, Messenger / Q000032:analysis*; D013381:Subtilisins / Q000235:genetics*
D017931:DNA Primers; D012333:RNA, Messenger; D043484:Proprotein Convertases; D013381:Subtilisins; D045706:Proprotein Convertase 2; D016282:Aspartic Acid Endopeptidases