ABSTRACT
We have previously reported that royal jelly (RJ) from honeybees (Apis mellifera) has weak estrogenic activity mediated by interaction with estrogen receptors that leads to changes in gene expression and cell proliferation. In this study, we isolated four compounds from RJ that exhibit estrogenic activity as evaluated by a ligand-binding assay for the estrogen receptor (ER) beta. These compounds were identified as 10-hydroxy-trans-2-decenoic acid, 10-hydroxydecanoic acid, trans-2-decenoic acid and 24-methylenecholesterol. All these compounds inhibited binding of 17beta-estradiol to ERbeta, although more weakly than diethylstilbestrol or phytoestrogens. However, these compounds had little or no effect on the binding of 17beta-estradiol to ERalpha. Expression assays suggested that these compounds activated ER, as evidenced by enhanced transcription of a reporter gene containing an estrogen-responsive element. Treatment of MCF-7 cells with these compounds enhanced their proliferation, but concomitant treatment with tamoxifen blocked this effect. Exposure of immature rats to these compounds by subcutaneous injection induced mild hypertrophy of the luminal epithelium of the uterus, but was not associated with an increase in uterine weight. These findings provide evidence that these compounds contribute to the estrogenic effect of RJ.
ABSTRACT
Renin is the rate limiting enzyme in the renin-angiotensin (RA) system that regulates blood pressure and electrolyte balance. In this study, we investigated the renin inhibitory effect of a royal jelly (RJ)-derived peptide. A dipeptide YY was isolated from the digested fraction of RJ proteins by proteases and was found to inhibit human renin activity. The inhibition constant (Ki) of YY was estimated to be 10 microM when the Km was 0.16 microM using sheep angiotensinogen as the substrate. The peptide was observed to lower blood pressure in spontaneously hypertensive rats.
Subject(s)
Dipeptides/pharmacology , Fatty Acids/chemistry , Insect Proteins/chemistry , Renin/metabolism , Angiotensinogen/genetics , Angiotensinogen/metabolism , Animals , Blood Pressure/drug effects , CHO Cells , Chromatography, High Pressure Liquid , Cricetinae , Cricetulus , DNA, Complementary/genetics , Dipeptides/chemistry , Dipeptides/metabolism , Enzyme-Linked Immunosorbent Assay , Fatty Acids/isolation & purification , Fatty Acids/metabolism , Female , Gene Transfer Techniques , Genetic Vectors/genetics , Humans , Hypertension/physiopathology , Hypertension/prevention & control , Insect Proteins/isolation & purification , Insect Proteins/metabolism , Molecular Structure , Peptide Hydrolases/metabolism , Rats , Rats, Inbred SHR , Recombinant Proteins/metabolism , Renin/genetics , Renin-Angiotensin System/drug effects , SheepABSTRACT
Royal jelly (RJ) from honeybees (Apis mellifera) is traditionally thought to improve menopausal symptoms. The potential estrogenic activities of RJ were investigated using various approaches. RJ competed for binding of 17beta-estradiol to the human estrogen receptor alpha and beta but its affinities were weak compared with diethylstilbestrol and phytoestrogens. The reporter gene expression assays suggested that 0.1-1 mg/ml RJ activated estrogen receptors, leading to enhanced transcription of a reporter gene through an estrogen-responsive element. 1 mg/ml RJ stimulated the mRNA expression of estrogen-responsive pS2 and vascular endothelial growth factor (VEGF) by increasing gene transcription in MCF-7 cells. Treatment with RJ at concentrations ranging from 0.5 to 1 mg/ml enhanced MCF-7 cell proliferation, but concomitant treatment with 1 microM tamoxifen blocked this effect. In vivo studies using ovariectomized rats showed that 17beta-estradiol (20 mg/kg, s.c.) treatment restored VEGF expression in both uterus and brain, whereas RJ (1 g/kg, s.c.) restored it in uterus but not in brain. These findings provide evidence that RJ has estrogenic activities through interaction with estrogen receptors followed by endogenous gene expressions.
Subject(s)
Estrogens/pharmacology , Fatty Acids/pharmacology , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Fatty Acids/metabolism , Female , Gene Expression/drug effects , Humans , RNA, Messenger/analysis , Rats , Rats, Inbred F344 , Receptors, Estrogen/metabolism , Trefoil Factor-1 , Tumor Suppressor Proteins/genetics , Vascular Endothelial Growth Factor A/geneticsABSTRACT
Brazilian propolis obtained from honeybee hives was extracted with water or ethanol. Cell growth-inhibitory activities of these propolis extracts were found in HL-60 human myeloid leukemia cells. The extracts-induced apoptosis in the cells, which was characterized by morphological and nucleosomal DNA fragmentation analysis. The apoptosis was mainly attributed to the induction of granulocytic differentiation, which was evaluated by nitro blue tetrazolium (NBT) reducing assays and cytofluorometric analysis for the expression of cell surface marker CD11b. DNA microarray analysis was performed to examine the gene expression profiles in the propolis-treated HL-60 cells accompanied with granulocytic differentiation, which were compared with those in all-trans retinoic acid-treated cells. Several genes were up- or down-regulated. Two genes encoding S100 calcium binding protein A9 and ferritin, heavy polypeptide 1 were up-regulated, which were also confirmed by semi-quantitative reverse transcriptase-PCR (RT-PCR). Propolis-induced growth inhibition in HL-60 cells was, at least in part, due to differentiation with gene expression profiles, which are similar to those induced by all-trans retinoic acid.