OBJECTIVETo establish a human breast cancer MCF-7 cell model stably overexpressing the aromatase gene (MCF-7-aromatase) and aromatase inhibitor letrozole-resistant MCF-7 cell model (MCF-7-LR).

METHODSWe utilized the lentivirus-mediated gene transfer approach to establish MCF-7-aromatase cell and MCF-7 cell model stably overexpressing green fluorescent protein (GFP) (MCF-7-GFP). The expression of aromatase in the MCF-7-aromatase and MCF-7-GFP cells was determined by reverse transcription polymerase chain reaction (RT-PCR), real time quantitative PCR (RT-qPCR), Western blot and immunoprecipitation (IP) assay. The proliferative ability in vitro of MCF-7-aromatase and MCF-7-GFP cells treated with testostorone and β-estradiol (E2) was determined by WST-1 cell proliferation assay. The proliferative ability of MCF-7-aromatase cells treated with letrozole was determined by WST-1 assay. The half maximal inhibitory concentration (IC50 value) for letrozole was calculated from the nonlinear regression line of the plot of cell viability (percentage of control) versus letrozole concentration using Graphpad Prism software. MCF-7-aromatase cells were continuously cultured in the presence of testosterone and letrozole, thus letrozole-resistant MCF-7-LR cells were obtained. WST-1 assay was performed to determine their chemoresistance to letrozole.

RESULTSRT-PCR and RT-qPCR results revealed that the mRNA expression of aromatase was significantly increased in the MCF-7-aromatase cells compared with that in the MCF-7-GFP cells. Both Western blot and IP assays showed that the expression of aromatase protein was drastically increased in the MCF-7-aromatase cells, compared with that in the MCF-7-GFP cells. WST-1 assay showed that the cell proliferation rate of MCF-7-aromatase cells treated with 1 and 10 nmol/L testosterone was 1.43- and 1.53-fold higher than that of the control cells, respectively. The proliferation rate of MCF-7-aromatase cells treated with 1 and 10 nmol/L E2 was 1.41- and 1.55-fold higher than that of the control cells, respectively. In contrast, the proliferation rate of MCF-7-GFP cells treated with 10 nmol/L testosterone was 1.12-fold higher than that of the control cells, and the proliferation rate of MCF-7-GFP cells treated with 1 and 10 nmol/L E2 was 1.41- and 1.51-fold higher than that of the control cells, respectively. Letrozole treatment significantly inhibited the testosterone-induced proliferation ability of MCF-7-aromatase cells in a dose-dependent manner and the IC50 value was 5.3 nmol/L. In contrast, letrozole treatment showed no inhibitory effect on the proliferative ability of MCF-7-LR cells and the IC50 value was >1000 nmol/L.

CONCLUSIONSMCF-7-aromatase and MCF-7-LR cells exhibit different response to letrozole treatment, which provides an important basis for further investigating the mechanism of letrozole resistance.

Antineoplastic Agents ; pharmacology ; Aromatase ; metabolism ; Aromatase Inhibitors ; pharmacology ; Breast Neoplasms ; Cell Proliferation ; Drug Resistance, Neoplasm ; Humans ; MCF-7 Cells ; Models, Biological ; Nitriles ; pharmacology ; Triazoles ; pharmacology

Aromatase is a key enzyme responsible for in vivo estrogen biosynthesis. Inhibition of the activity of the aromatase has become an alterative way for treatment of breast cancer. In this review, the structure and catalytic mechanism of the aromatase is briefly introduced followed by thorough review of the progress in the study of the steroidal and non-steroidal aromatase inhibitors. This review is focused on the natural compounds that exhibit the aromatase inhibition, which include flavonoids, xanthones, coumarins, and sesquiterpenes. The structure-activity relationship of these compounds is also discussed.
Androstenedione ; analogs & derivatives ; Antineoplastic Agents ; chemistry ; pharmacology ; therapeutic use ; Aromatase ; chemistry ; metabolism ; pharmacology ; Aromatase Inhibitors ; chemistry ; classification ; pharmacology ; therapeutic use ; Breast Neoplasms ; drug therapy ; Catalysis ; Coumarins ; chemistry ; pharmacology ; Estrogens ; biosynthesis ; Flavonoids ; chemistry ; pharmacology ; Humans ; Inhibitory Concentration 50 ; Nitriles ; chemistry ; pharmacology ; Sesquiterpenes ; chemistry ; pharmacology ; Structure-Activity Relationship ; Triazoles ; chemistry ; pharmacology ; Xanthones ; chemistry ; pharmacology

OBJECTIVETo explore the effect mechanism of Sanlengwan (SLW) on estrogen production in ectopic endometrium of rats.

METHODThe rat model of endometriosis was established by surgical implant of endometrial tissue which belong to its body. Forty EMS model rats were randomly divided into five groups (n = 8): model control group, three different concentration SLW groups and anastrozole group. Meanwhile, eight normal rats were used as the normal control group. All the rats were treated for 4 weeks respectively, the changes of the P450 arom and cyclooxygenase-2 protein were measured by immunohistochemical test and western blot respectively before and after treatment of SLW, and the level of secretion of estrodiol and prostaglandin E2 was also measured by ECLIA and RIA.

RESULTSLW can reduce the expression of P450 arom protein, and the levels of estradiol after treatment of SLW were significantly lower than that of the model group in ectopic endometrial tissue (P < 0. 05); The high dose group of SLW can inhibit the expression of cyclooxygenase-2 protein and also reduce the production of prostaglandin E2 (P < 0.05).

CONCLUSIONSLW can reduce the production of estradiol in the ectopic endometrial tissue of rats, and its mechanism might be associated with inhibiting the expression of P450 arom and interruption the positive feedback loop of estradiol production.

Animals ; Aromatase ; metabolism ; Aromatase Inhibitors ; pharmacology ; Cyclooxygenase 2 ; metabolism ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Cytochrome P-450 Enzyme System ; metabolism ; Dinoprostone ; biosynthesis ; Dose-Response Relationship, Drug ; Endometriosis ; enzymology ; pathology ; Endometrium ; drug effects ; metabolism ; Estradiol ; biosynthesis ; Female ; Gene Expression Regulation, Enzymologic ; drug effects ; Rats ; Rats, Wistar

The localization of estrogen (E2) has been clearly shown in hippocampus, called local hippocampal E2. It enhanced neuronal synaptic plasticity and protected neuron form cerebral ischemia, similar to those effects of exogenous E2. However, the interactive function of hippocampal and exogenous E2 on synaptic plasticity activation and neuroprotection is still elusive. By using hippocampal H19-7 cells, we demonstrated the local hippocampal E2 that totally suppressed by aromatase inhibitor anastrozole. Anastrozole also suppressed estrogen receptor (ER)beta, but not ERalpha, expression. Specific agonist of ERalpha (PPT) and ERbeta (DPN) restored ERbeta expression in anastrozole-treated cells. In combinatorial treatment with anastrozole and phosphoinositide kinase-3 (PI-3K) signaling inhibitor wortmannin, PPT could not improve hippocampal ERbeta expression. On the other hand, DPN induced basal ERbeta translocalization into nucleus of anastrozole-treated cells. Exogenous E2 increased synaptic plasticity markers expression in H19-7 cells. However, exogenous E2 could not enhance synaptic plasticity in anastrozole-treated group. Exogenous E2 also increased cell viability and B-cell lymphoma 2 (Bcl2) expression in H2O2-treated cells. In combined treatment of anastrozole and H2O2, exogenous E2 failed to enhance cell viability and Bcl2 expression in hippocampal H19-7 cells. Our results provided the evidence of the priming role of local hippocampal E2 on exogenous E2-enhanced synaptic plasticity and viability of hippocampal neurons.
Androstadienes/pharmacology ; Animals ; Aromatase Inhibitors/pharmacology ; Cell Line ; Cell Survival/drug effects ; Estrogen Receptor alpha/agonists/metabolism ; Estrogen Receptor beta/agonists/metabolism ; Estrogens/*metabolism/pharmacology ; Hippocampus/cytology/*metabolism ; Hydrogen Peroxide/pharmacology ; Nervous System/*drug effects ; Neuronal Plasticity/*drug effects ; *Neuroprotective Agents ; Nitriles/pharmacology ; Phosphatidylinositol 3-Kinase/antagonists & inhibitors ; Proto-Oncogene Proteins c-bcl-2/biosynthesis ; Rats ; Triazoles/pharmacology

Flavonoids are present in fruits, vegetables and beverages derived from plants, and in many dietary supplements or herbal remedies. A number of naturally occurring flavonoids have been shown to modulate the CYP450 system, including the induction or inhibition of these enzymes. This review focuses on the flavonoid effects on cytochrome P450 (CYP) enzyme CYP1, 2E1, 3A4 and 19. Flavonoids alter CYPs by various mechanisms, including the stimulation of gene expression via specific receptors and/or CYP protein, or mRNA stabilization and so on. But in vivo and in vitro, the effects of flavonoids are not always coincident as a result of concentrations of flavonoids, genetic and environmental factors. As well, flavonoids may interact with drugs through the induction or inhibition of their metabolism. Much attention should be paid to the metabolism interaction of the flavonoids when coadministered with other drugs.
Animals ; Aromatase ; genetics ; metabolism ; Cytochrome P-450 CYP1A1 ; antagonists & inhibitors ; genetics ; metabolism ; Cytochrome P-450 CYP2E1 ; genetics ; metabolism ; Cytochrome P-450 CYP2E1 Inhibitors ; Cytochrome P-450 CYP3A ; genetics ; metabolism ; Cytochrome P-450 CYP3A Inhibitors ; Cytochrome P-450 Enzyme Inhibitors ; Cytochrome P-450 Enzyme System ; genetics ; metabolism ; Enzyme Activation ; drug effects ; Flavonoids ; pharmacology ; Humans ; RNA, Messenger ; genetics ; metabolism