Widespread expression of parathyroid hormone-related peptide in melanocytic cells.
BACKGROUND
Parathyroid hormone-related peptide (PTH-rP) was associated with the syndrome of hypercalcaemia of malignancy. An increased serum level of PTH-rP could occur in patients with advanced melanoma.


OBJECTIVE
We examined PTH-rP expression in cultured melanocytic cell lines and in lesions of melanocytic origin for associations with clinicopathological variables of disease progression. We measured the supernatant and cell lysate level of PTH-rP in cultured melanoma cells to clarify whether melanoma cells secrete PTH-rP.


METHODS
PTH-rP expression was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in cultured melanocytic cell lines and by immunoperoxidase staining in 18 melanocytic naevi, 40 primary melanoma and 19 metastatic melanoma lesions. The supernatant level of PTH-rP was measured with an immunoradiometric assay.


RESULTS
RT-PCR products of PTH-rP mRNA were detected in six of eight melanoma cell lines; however, neither naevus cells nor melanocytes showed positive products. On the other hand, immunohistochemical analysis showed that PTH-rP was widely expressed both in benign and malignant melanocytic lesions. In addition, PTH-rP expression was not associated with any clinicopathological variables. Cell lysate but not the supernatant of melanoma cells showed high PTH-rP levels.


CONCLUSIONS
These results suggest that PTH-rP was widely expressed in melanocytic cells; however, the cells did not secrete PTH-rP.
Kageshita
T
T
Department of Dermatology, Kumamoto University School of Medicine, 1-1 Honjo, Kumamoto 860-0811, Japan. toshiro@kaiju.medic.kumamoto-u.ac.jp
Ishihara
T
T
Tokuo
H
H
Funasaka
Y
Y
Ichihashi
M
M
Dong
J
J
Nakajima
M
M
Ono
T
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008544:Melanocytes / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism*; D008875:Middle Aged; D009506:Nevus / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000032:analysis* / Q000097:blood; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012878:Skin Neoplasms / Q000378:metabolism*; D014407:Tumor Cells, Cultured
C470121:PTHLH protein, human; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones; D012333:RNA, Messenger