Potential regulation of PTH/PTHrP receptor expression in choriocarcinoma cells.
OBJECTIVE
Parathyroid hormone-related peptide (PTHrP) have been found to be expressed in a variety of human tumors. Parathyroid hormone-related peptide is known as the major mediator of humoral hypercalcemia of malignancy, may also regulate placental calcium flux, uterine contraction and fetal tissue development. The purpose of this study is to evaluate the expression of PTH/PTHrP receptor in choriocarcinoma JAR cell line.


METHODS
This study was carried out at the Department of Biochemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia, between November 2002 and August 2003. Choriocarcinoma JAR cell line treated for 12 and 72 hours with epidermal growth factor, (EGF) (20ng/ml), estradiol, E2 (10(-8) M), dexamethasone, (DEX) (10(-8) M) or 1,25 dihydroxycholecalciferol, 1,25 (DHCC) (10(-8) M). We investigated the expression of parathyroid hormone (PTH)/PTHrP receptor in JAR cell line with these treatments compared with untreated JAR cells. The PTH/PTHrP receptor expression were detected with 3.3nM 125I-PTHrP-34Tyrosine.


RESULTS
The expression of the receptors at 12 hours were increased following exposure to EGF, E2 or DEX, whereas 1,25 DHCC inhibited the receptor expression. In further experiments at 72 hours with the same treatments, the receptors expression were remarkably increased with EGF, E2 or DEX, whereas, 1,25 DHCC inhibited the receptor expression in these cells.


CONCLUSIONS
These data suggested that in JAR cells, The EGF, E2 and DEX upregulated the PTH/PTHrP receptor expression, whereas the 1,25 DHCC down-regulated the PTH/PTHrP receptor, and the 1,25 DHCC may play an important role as antiproliferative drug for choriocarcinoma.
Alokail
Majed S
MS
Department of Biochemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia. msalokail@yahoo.com
D002117:Calcitriol / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002822:Choriocarcinoma / Q000503:physiopathology*; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D010281:Parathyroid Hormone / Q000378:metabolism*; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic / Q000503:physiopathology*; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects; D014594:Uterine Neoplasms / Q000503:physiopathology*
D010281:Parathyroid Hormone; D044168:Receptor, Parathyroid Hormone, Type 1; D004958:Estradiol; D004815:Epidermal Growth Factor; D003907:Dexamethasone; D002117:Calcitriol