Caveolin-1在大鼠腦垂腺瘤細胞株的功能性研究
The Functional Study of Caveolin-1 in Rat Pituitary Tumor Cell Line
Date Issued
2004
Date
2004
Author(s)
Li, Yi-Hung
DOI
zh-TW
Abstract
Mammary gland can proliferate and regress many times in the life time of female mammals. The abnormal regulation of its development may induce irregular proliferation and tumorigenesis of mammary epithelial cells. Prolactin （PRL） is a major regulator for mammary gland development and lactation and is secreted by anterior pituitary gland. Prolactinoma is a common disease in human, its symptoms are accompanied with abnormal proliferation of anterior pituitary gland and hyperprolactinemia. Bromocriptine, a dopamine D2 receptor agonist, is commonly used to cure prolactinoma. Bromocriptine can induce cell apoptosis and decrease PRL secretion and shrink prolactinoma. GH3 cell line, from rat pituitary tumor, which can synthesize and secrete both prolactin and grow hormone, is a useful model system for the study of hormonal dysfunctions. However, its molecular mechanism in regulating GH3 cell apoptosis is still not clear.
Caveolin-1, a 23 kDa membrane anchored protein, correlates with lipid transport, membrane traffic, signal transduction, is also been hypothesized as a negative regulator of many signal transduction. Caveolin-1 was cloned by RNA substraction technology and it expressed abundantly in normal mammary epithelial cells compared to tumorous mammary epithelial cells, suggesting that it is a tumor suppressing gene. Here we focus on the role of caveolin-1 in neuro-endocrine system.
According to the RT-PCR results, we found that caveolin-1 was expressed both in GH3 and mouse brain tissue. The expression level in mouse brain was elevated at gestation day 18. We successfully cloned caveolin-1 gene from adult mouse brain tissue which was then fused to myc-tag in N-terminal of caveolin-1. Enhanced green fluorescent protein （EGFP） was constructed in the same strategy and was used as a control. These recombinant DNAs were subcloned into a vector driven by cytomegalovious promoter and then transfected separately into GH3 cells. The morphology of GH3 cells appeared to shrink following expression of caveolin-1, while the cells expressing EGFP maintained the normal cell morphology even at 48 hours after transfection. Further more, hoechst stained caveolin-1 expressing GH3 cells showed chromatolysis and the character of cell and cell apoptosis was confirmed by TUNEL assay. To obtain this data, we hypothesize that caveolin may play a role in bromocriptine induced GH3 apoptosis. To explore this, bromocriptine was used to treat GH3 cells for 24 hours, total RNA from the cells were extracted and expression level of caveolin-1 mRNA estimated by semi-quantitative PCR method. The data shows that expression of endogenous caveolin-1 mRNA was elevated following bromocriptine treatment. These results indicate that caveolin-1 possibly play a pivotal role in bromocriptine induce apoptosis in GH3 cells.
Subjects
caveolin-1
細胞凋亡
apoptosis
SDGs
Type
thesis
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