[The effects of continuous stimulation with different doses of parathyroid hormone 1-34 fragment on human SaoS-2 cells].
OBJECTIVE
To observe the effects of different doses of human parathyroid hormone fragment (hPTH)1-34 on SaoS cells and to explore the signal pathway and mechanism.


METHODS
5 x 10(4) cells/ml SaoS cells were seeded. Doses of 5, 50, 500 and 5 000 micro g/L hPTH1-34 were supplemented respectively. Total RNA was extracted by Trizol kit. Alkaline phosphatase (ALP), osteocalcin (BGP) and cAMP concentrations were measured by chemical, radioimmunoassay and competitive protein binding methods. c-fos gene expression level was semi-quantified by reverse transcriptase (RT)-PCR.


RESULTS
ALP activity was higher in 500 micro g/L dose (P < 0.05 vs. control). BGP level was inhibited in 5 000 micro g/L dose (P < 0.05 vs. control and pretreatment). 50 and 500 micro g/L hPTH1-34 enhanced cAMP level significantly (P < 0.05 vs. control). No obvious increase of cAMP level was found in 5 000 micro g/L and 5 micro g/L dose groups (P > 0.05 vs. control and pretreatment). c-fos expression was higher in 50 and 500 micro g/L group.


CONCLUSIONS
Different doses of hPTH1-34 exert distinct effects on osteoblasts. hPTH1-34 affects ALP and c-fos depending on protein kinase A signal pathway. hPTH1-34 exerts its action via regulation of osteoblasts by c-fos.
Li
Mei
M
Department of Endocrinology, Peking Union Medical College Hospital, Peking Unoin Medical College, Chinese Academy of Medical Science, Beijing 100730, China. limeilzh@yahoo.com
Meng
Xun-wu
XW
Zhou
Xue-ying
XY
Xing
Xiao-ping
XP
Liu
Huai-cheng
HC
D000469:Alkaline Phosphatase / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010006:Osteoblasts / Q000187:drug effects / Q000473:pathology; D015675:Osteocalcin / Q000378:metabolism; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D015675:Osteocalcin; D000242:Cyclic AMP; D000469:Alkaline Phosphatase