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Hypoxia downregulates continuous and interleukin-1-induced expression of human chorionic gonadotropin in
1Department of Obstetrics and Gynecology, University of Vienna, Austria.
Abstract:
The effects of hypoxia on JEG-3, BeWo, and JAr cells were investigated and it was demonstrated that choriocarcinoma cells can be used as a model to study the molecular mechanism of hypoxia-mediated repression of human chorionic gonadotropin (hCG). Cells were maintained under hypoxia (3.5 per cent O2) for 72 h without loss of variability, as demonstrated by the fact that 93-98 per cent of the cells excluded trypan blue. Up to 48 h, cell growth was not significantly influenced by hypoxia, and analysis by flow cytometry did not reveal major changes in cell cycle distribution. JEG-3, BeWo, and JAr cells which were grown for 48 h under hypoxia secreted 81, 67, and 71 per cent less hCG than cells cultivated under normoxic conditions. The extent of hCG reduction was dependent on the oxygen concentration. Moreover, release of the hormone from hypoxic JAr cells was not stimulated upon addition of interleukin-1 (IL-1). Treatment of JEG-3 cells with methotrexate (MTX) led to a 4.3-fold augmentation in hCG secretion and to an increase in the amount of G0/G1 cells. However, when cells were cultured in the presence of MTX and hypoxia, hCG secretion decreased 10-fold and beta hCG mRNA declined to almost undetectable levels suggesting that downregulation of beta hCG mRNA is the major cause of diminished hCG release under hypoxic conditions.
Insights
Hypoxia significantly reduces human chorionic gonadotropin (hCG) secretion in choriocarcinoma cells by downregulating beta hCG mRNA. These cells serve as a model for studying hypoxia
Area of Science:
- Reproductive biology
- Cellular and molecular physiology
- Cancer research
Background:
- Choriocarcinoma cells are utilized to investigate the molecular mechanisms underlying hypoxia's impact on human chorionic gonadotropin (hCG) production.
- Hypoxia, a condition of low oxygen, is known to affect cellular functions and gene expression.
Purpose of the Study:
- To investigate the effects of hypoxia on JEG-3, BeWo, and JAr choriocarcinoma cells.
- To determine the molecular mechanism of hypoxia-mediated repression of hCG secretion.
- To assess the role of beta hCG mRNA in hCG reduction under hypoxic conditions.
Main Methods:
- Choriocarcinoma cells (JEG-3, BeWo, JAr) were cultured under hypoxic (3.5% O2) and normoxic conditions.
- Cell viability was assessed using trypan blue exclusion.
- Cell cycle distribution was analyzed by flow cytometry.
- hCG secretion levels were measured under varying oxygen concentrations and in response to interleukin-1 (IL-1) and methotrexate (MTX).
- Beta hCG mRNA levels were quantified.
Main Results:
- Hypoxia for 72 hours did not affect cell viability or significantly alter cell cycle distribution up to 48 hours.
- Hypoxic cells showed significantly reduced hCG secretion (81% in JEG-3, 67% in BeWo, 71% in JAr) compared to normoxic cells.
- hCG reduction was oxygen-dependent and IL-1 did not stimulate hCG release from hypoxic JAr cells.
- Methotrexate treatment increased hCG secretion and G0/G1 cells in normoxia, but combined MTX and hypoxia led to a 10-fold decrease in hCG secretion and near-undetectable beta hCG mRNA levels.
Conclusions:
- Choriocarcinoma cells provide a valid model for studying hypoxia-mediated repression of hCG.
- Downregulation of beta hCG mRNA is the primary cause of diminished hCG release under hypoxic conditions.
- Hypoxia significantly impacts hCG production, with implications for understanding placental function and choriocarcinoma biology.