Type II oestrogen binding sites in acute lymphoid and myeloid leukaemias: growth inhibitory effect of oestrogen and flavonoids

Sex disparity in acute myeloid leukaemia with FLT3 internal tandem duplication mutations: implications for prognosis

Incidence, molecular presentation and outcome of acute myeloid leukaemia (AML) are influenced by sex, but little attention has been directed at untangling sex‐related molecular and phenotypic differences between female and male patients. While increased incidence and poor risk are generally associated with a male phenotype, the poor prognostic FLT3 internal tandem duplication (FLT3‐ITD) mutation and co‐mutations with NPM1 and DNMT3A are overrepresented in female AML. Here, we have investigated the relationship between sex and FLT3‐ITD mutation status by comparing clinical data, mutational profiles, gene expression and ex vivo drug sensitivity in four cohorts: Beat AML, LAML‐TCGA and two independent HOVON/SAKK cohorts, comprising 1755 AML patients in total. We found prevalent sex‐associated molecular differences. Co‐occurrence of FLT3‐ITD, NPM1 and DNMT3A mutations was overrepresented in females, while males with FLT3‐ITDs were characterized by additional mutations in RNA splicing and epigenetic modifier genes. We observed diverging expression of multiple leukaemia‐associated genes as well as discrepant ex vivo drug responses, suggestive of discrete functional properties. Importantly, significant prognostication was observed only in female FLT3‐ITD‐mutated AML. Thus, we suggest optimization of FLT3‐ITD mutation status as a clinical tool in a sex‐adjusted manner and hypothesize that prognostication, prediction and development of therapeutic strategies in AML could be improved by including sex‐specific considerations.

Estrogen Receptors Alpha and Beta in Acute Myeloid Leukemia

Estrogen receptor (ER) signaling has been widely studied in a variety of solid tumors, where the differential expression of ERα and ERβ subtypes can impact prognosis. ER signaling has only recently emerged as a target of interest in acute myeloid leukemia (AML), an aggressive hematological malignancy with sub-optimal therapeutic options and poor clinical outcomes. In a variety of tumors, ERα activation has proliferative effects, while ERβ targeting results in cell senescence or death. Aberrant ER expression and hypermethylation have been characterized in AML, making ER targeting in this disease of great interest. This review describes the expression patterns of ERα and ERβ in AML and discusses the differing signaling pathways associated with each of these receptors. Furthermore, we assess how these signaling pathways can be targeted by various selective estrogen receptor modulators to induce AML cell death. We also provide insight into ER targeting in AML and discuss pending questions that require further study.

Protective and Curative Effects of Aqueous Extract of Terfezia Boudieri (Edible Desert Truffle Specie) against Paracetamol Acute Toxicity in the Rat

The current study was aimed to evaluate the protective and curative effect of aqueous extract of edible desert truffle specie (Terfezia boudieri) against rat's liver and kidney injuries induced by paracetamol (PCM). Terfezia boudieri was genetically identified by PCR and then sequencing (Genbank NCBI: LT718236.1). Terfezia boudieri aqueous extract (TBAE) was characterized by antioxidant capacity evaluated by 1,1-diphenyl-2-picryl-hydrazyl test (EC₅₀ = 0.415 mg/ml). LC-MS analysis shows that TBAE contains several actives biomolecules such as B3 vitamin (2.73 ± 0.3 mg/100g dm), quinic acid (2 ± 0.22 mg/100g dm), chlorogenic acid (0.18 ± 0.02 mg/100g dm) and quercetin-3-o-rhamonoside (0.09 ± 0.01 mg/100g dm). Liver and kidney Biochemical parameters showed no significant variation in rat's plasma treated with PCM and/or TBAE. However, the histological studies showed that the liver injuries induced by PCM were characterized by hemorrhage and inflammation. The pretreatment by TBAE showed preservation of normal liver and kidney architecture, this finding suggests its protective effects on these two organs. The co-treatment by TBAE reduced the PCM hepatotoxicity proved by normal central vein and small vacuols. In addition, TBAE reduced kidney PCM toxicity proved by less area inflammation and normal glomerulus. Therefore, TBAE is promoting eventual protective and curative drug against acute toxicity.

The Epidemiological Trend of Acute Myeloid Leukemia in Childhood: a Population-Based Analysis

Acute myeloid leukemia (AML) is the fifth most common malignancy in children, and the prognosis for AML in children remains relatively poor. However, its incidence and survival trends based on a large sample size have not been reported.

Children diagnosed with AML between 1975 and 2014 were accessed from the Surveillance, Epidemiology, and End Results database. Incidence and survival trends were evaluated by age-adjusted incidence and relative survival rates (RSRs) and Kaplan-Meier analyses. Cox regression was performed to identify independent risk factors for child AML death.

The overall incidence of AML in childhood increased each decade between 1975 and 2014, with the total age-adjusted incidence increasing from 5.766 to 6.615 to 7.478 to 7.607 per 1,000,000 persons. In addition, the relative survival rates of AML in childhood improved significantly, with 5-year RSRs increasing from 22.40% to 39.60% to 55.50% to 68.30% over the past four decades (p < 0.0001). Furthermore, survival disparities among different races and socioeconomic statuses have continued to widen over the past four decades. Multivariate Cox regression analyses showed a higher risk of death in Black patients (HR = 1.245, 95% CI: 1.077-1.438, p = 0.003) with Whites as a reference.

These results may help predict future trends for AML in childhood, better design clinical trials by eliminating disparities, and ultimately improve clinical management and outcome.

The epidemiological trend of acute promyelocytic leukemia over past four decades: a population-based analysis

The treatment regimens for acute promyelocytic leukemia (APL) dramatically changed over time. However, its survival trend, based on a large sample size has not been reported. Patients diagnosed with APL were accessed from the Surveillance, Epidemiology, and End Results database. Their incidence and survival trend were evaluated in overall and subgroup levels. The overall incidence of APL increased with an annual percentage change of 5.5% from 1992 to 2006 and remained stable thereafter. In addition, the 5-year relative survival rates of APL improved significantly, from 12.3 to 32.2% to 59.5 to 72.1% over past four decades (p < .0001), sharing similar trend with different subgroups. Importantly, survival disparities exist among races and different socioeconomic status groups, with superior survival in whites and patients in low-poverty regions. Increasing incidence urges for increased awareness of clinicians over diagnosis of APL. In addition, a wider insurance coverage may help balance survival gap.

Synergistic effect of quercetin and pH-responsive DEAE-chitosan carriers as drug delivery system for breast cancer treatment

Amphiphilic chitosans, which may self-assemble in aqueous solution to form nanoaggregates with different conformations depending to the environmental pH, can be used as drug transport and delivery agents, when the target pH differs from the delivery medium pH. In this study, quercetin, a bioactive flavonoid, was encapsulated in a pH-responsive system based on amphiphilic chitosan. The hydrophilic reagent 2-chloro-N,N-diethylethylamine hydrochloride (DEAE), also known to inhibit the proliferation of cancer cells, was used as a grafting agent. Drug loading experiments (DL ∼5%) showed a quercetin entrapment efficiency of 73 and 78% for the aggregates. The sizes of blank aggregates measured by dynamic light scattering (DLS) varied from 169 to 263nm and increased to ∼410nm when loaded with quercetin. The critical aggregation concentration, zeta potential and morphology of the aggregates were determined. pH had a dominant role in the release process and Fickian diffusion was the controlling factor in drug release according to the Korsmeyer-Peppas mathematical model. In vitro studies indicated that the DEAE-modified chitosan nanoaggregates showed a synergistic effect with quercetin on the control of the viability of MCF-7 cells. Therefore, DEAE-modified chitosan nanoaggregates with pH-sensibility can be used as optimized nanocarriers in cancer therapy.

Leaf extracts from Teucrium ramosissimum protect against DNA damage in human lymphoblast cell K562 and enhance antioxidant, antigenotoxic and antiproliferative activity

The in vitro antioxidant, antigenotoxic and antiproliferative activities of Teucrium ramosissimum extracts were investigated. The antioxidant activities of the tested extracts were evaluated through three chemical assays: The Cupric reducing antioxidant capacity, the reducing power and the ferric reducing antioxidant power. TR1 fraction from methanol extract showed the best antioxidant activity evaluated by the CUPRAC, RP and FRAP assays with TEAC values of 4.04, 1.77 and 1.48μM respectively compared to control. Yet, TR2 fraction exhibited the lowest antioxidant effect with a TEAC values of 1.97, 0.408 and 0.35μM respectively. All the tested extracts were also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals. Furthermore, the effects of T. ramosissimum extracts on cell proliferation were also examined. The cytotoxic study revealed that methanol extract significantly inhibited the proliferation of K562 cells (IC50=150μg/mL). The antigenotoxic properties of these extracts were investigated by assessing the induction and inhibition of the genotoxicity induced by the direct-acting mutagen, hydrogen peroxide (H2O2), using an eukaryotic system; the "Comet assay." The results showed that all the extracts inhibited the genotoxicity induced by H2O2, and particularly TR2 fraction (96.99%) and methanol extract (96.64%). The present study has demonstrated that T. ramosissimum extract possess potent antioxidant, antiproliferative and antigenotoxic activities, which could be derived from compounds such as flavonoids and polyphenols.

Polyaminocyclodextrin nanosponges: synthesis, characterization and pH-responsive sequestration abilities

New pH-responsive nanosponges were obtained by reacting four different polyaminocyclodextrins with heptakis-(6-bromo)-(6-deoxy)-β-cyclodextrin.

Hormonal and Reproductive Factors and Risk of Myeloproliferative Neoplasms in Postmenopausal Women

BACKGROUND

Hormonal and reproductive history has been associated with risk of some hematologic malignancies, but their role in myeloproliferative neoplasms (MPN) is largely unknown.

METHODS

Using a population-based cohort study, we evaluated the association of these factors with risk of MPN overall, and for essential thrombocythemia (ET) and polycythemia vera (PV) specifically. Incident MPN cases from 1993 to 2004 were identified via linkage to Medicare. RR and 95% confidence intervals (CI) were estimated utilizing Cox proportional hazard regression.

RESULTS

After >250,000 person-years of follow-up, 257 cases of MPN were identified (172 ET, 64 PV). Ever use of hormone therapy (HT) was associated with an increased risk of ET (RR = 1.63; 95% CI, 1.19-2.23) but a decreased risk of PV (RR = 0.58; 95% CI, 0.34-0.98). There were no statistically significant associations of oral contraceptives or reproductive factors with MPN risk overall, or by MPN subtype. Bilateral oophorectomy was associated with increased risk of ET (RR = 1.58; 95% CI, 1.11-2.25) and decreased risk of PV (RR = 0.32; 95% CI, 0.12-0.88). There was no association of ovulatory years with ET risk; however, there was increased risk of PV (RR = 1.68 for >36.8 compared with ≤27.6 years; P trend = 0.045). Adjustment for potential confounding factors did not alter these associations.

CONCLUSIONS

HT use and bilateral oophorectomy had opposite associations for ET and PV. Except for ovulatory years and PV risk, reproductive history did not appear to play a role in the etiology of MPN.

IMPACT

This study suggests different mechanistic impacts of estrogen, and perhaps distinct etiologies, for the two major MPN subtypes.

Osteogenic differentiation of adipose-derived stem cells promoted by quercetin

OBJECTIVES

The present study aimed to investigate overall effect of quercetin on proliferation and osteogenic differentiation of mouse adipose stem cells (mASCs) in vitro.

MATERIALS AND METHODS

Mouse adipose stem cells were isolated from subcutaneous fat pads and induced into the osteogenic lineage. Effects of quercetin on cell proliferation were assessed using MTT assay. Then they were treated by quercetin for 3, 7 and 11 days in a range of concentrations. Finally, effects of quercetin on osteogenic differentiation of mASCs were analysed by real-time PCR.

RESULTS

Data of MTT assay showed that quercetin did not enhance mASC proliferation in a dose-dependent or time-dependent manner. Results of qPCR indicated that quercetin promoted expressions of Osx, Runx2, BMP-2, Col-1, OPN and OCN at the mRNA level in the presence of osteo-induction medium.

CONCLUSIONS

Our data demonstrated that quercetin was not active in terms of enhancing mASCs proliferation; however, it increased osteogenesis of mASCs by up-regulation of genes including Osx, Runx2, BMP-2, Col-1, OPN and OCN.

Flavonoids and sesquiterpenes from Tecurium ramosissimum promote antiproliferation of human cancer cells and enhance antioxidant activity: a structure-activity relationship study

Fractionation of the chloroformic extracts from Teucrium ramosissimum leaves resulted in the isolation of three flavonoids: genkwanin (1), cirsimaritin (2) and 4',7-dimethoxy apigenin (4) and one sesquiterpene: β-eudesmol (3). The structures were determined using data obtained from (1)H and (13)C NMR spectra, as well as by various correlation experiments (COSY, HMQC and HMBC). The antioxidant activities of the isolated flavonoids from T. ramosissimum leaves were evaluated by measuring their ability to scavenge the radical ABTS(+) and through chemical assays: cupric reducing antioxidant capacity (CUPRAC), reducing power (RP) and ferric reducing antioxidant power (FRAP). Furthermore, the effects of T. ramosissimum isolated molecules, on inhibition of cell proliferation and induction of apoptosis in human leukemia cells, were also examined. Cirsimaritin showed the best activity in the ABTS assay with TEAC value 2.04μM, whereas apigenin and 4',7-dimethoxy apigenin exhibited the highest antioxidant activity using the CUPRAC, RP and FRAP assays with TEAC values 10.5, 1.39 and 0.71μM respectively. The cytotoxic activity revealed that the β-eudesmol inhibited significantly the proliferation of K562 cells (IC(50)=20μg/ml).

Differential effects of two citrus flavanones on bone quality in senescent male rats in relation to their bioavailability and metabolism

The effect of hesperidin (Hp) and naringin (Nar), two major citrus flavanones, on the regulation of bone metabolism was examined in male senescent rats. Twenty -month -old gonad-intact male Wistar rats received a casein-based diet supplemented with or without either 0.5% hesperidin (Hp), 0.5% naringin (Nar) or a mix of both flavanones (Hp+Nar, 0.25% each). After 3 months, daily Hp intake significantly improved femoral bone integrity as reflected by improvements in total and regional bone mineral densities (BMD) (9.7%-12.3% improvements, p<0.05) and trabecular bone volume fraction (24.3% improvement, p<0.05) at the femur compared with control group. In contrast, naringin exerted site-specific effects on BMD (10.2% improvement at the distal metaphyseal area, p<0.05) and no further benefit to bone mass was observed with the mix of flavanones. Bone resorption (DPD) was significantly attenuated by Hp and Nar given alone (40.3% and 26.8% lower compared to control, p<0.05, respectively) but not by the mixture of the two. All treatments significantly reduced expression of inflammatory markers to a similar extent (IL-6, 81.0-87.9% reduction; NO, 34.7-39.5% reduction) compared to control. Bone formation did not appear to be strongly affected by any of the treatments (no effect on osteocalcin levels, modest modulation of tibial BMP-2 mRNA). However, as previously reported, plasma lipid-lowering effects were observed with Hp and Nar alone (34.1%-45.1% lower for total cholesterol and triglycerides compared to control, p<0.05) or together (46% lower for triglycerides, p<0.05). Surprisingly the plasma circulating level of naringin (8.15μM) was >5-fold higher than that of hesperidin (1.44μM) at equivalent doses (0.5%) and a linear reduction in plasma levels was observed upon co-administration (0.25% each) indicating absence of competition for their intestinal absorption sites and metabolism. The higher efficacy of Hp at a lower plasma concentration than naringin, as well as the identification of the major circulating metabolite of hesperidin (hesperetin-7-O-glucuronide) underlines the importance of flavanone bioavailability and metabolism in their biological efficacy and suggests a structure-function relationship in the mechanism of action of the active metabolites.

Phytochemical, antibacterial, antiproliferative, and antioxidant potentials and DNA damage-protecting activity of Acacia salicina extracts

The extract enriched in total oligomer flavonoids (TOF), and the aqueous, methanol, and ethyl acetate extracts of Acacia salicina were investigated for their polyphenolic compound content, antioxidative activity in the nitro blue tetrazolium/riboflavin assay system, antibacterial activity against Gram-positive and Gram-negative bacterial reference strains, antigenotoxic activity tested with the Ames assay, and cytotoxic activity against the K562 human chronic myelogenous leukemia cell line and L1210 leukemia murine cells. TOF extract was effective at inhibiting nitro blue tetrazolium reduction by superoxide radical in a nonenzymatic O(2)(*-)-generating system. Significant activity against bacterial reference strains Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis, and Salmonella typhimurium was shown with all the tested extracts. These extracts significantly decreased the genotoxicity induced by sodium azide and 4-nitro-o-phenylenediamine. A pronounced cytotoxic effect on both leukemia cell lines was detected in TOF, methanolic and ethyl acetate extracts. The antioxidant, antimicrobial, antigenotoxic, and cytotoxic activities exhibited by A. salicina depended on the chemical composition of the tested extracts.

Decreased B16F10 melanoma growth and impaired tumour vascularization in BDF1 mice with quercetin-cyclodextrin binary system

The aim of this work was to study the inclusion behaviour of a poorly water-soluble bioflavonoid, quercetin, towards sulfobutyl ether-7beta-cyclodextrin. It also involves angiogenesis inhibition in-vivo in addition to in-vitro human cancer cell growth inhibition study of quercetin and its cyclodextrin complex. Drug-cyclodextrin solid inclusion complexes were prepared and characterized in solution and in the solid state. An in-vitro anti-proliferation study using plain drug and its solubilized form was carried out on human cancer cell lines of different origin. Further, an in-vivo tumour growth inhibition study was carried out using a mouse melanoma model. Histological sections of tumours were examined for the evaluation of tumour microvessel density. Significant enhancement of the solubility and dissolution rate of the quercetin, which occurred after complexation, might be attributed to the decrease in crystallinity of drug. SBE7betaCD complex of quercetin was more potent for inhibiting cell proliferation in human erythroleukaemia and cervix cancer cells. Decreased tumour microvessel density in mouse melanoma after oral quercetin administration led to diminished tumour cell proliferation. Quercetin-SBE7betaCD complex showed significantly improved anti-cancer activity at much lower concentration than the plain drug, providing evidence for dose reduction without affecting therapeutic efficacy when using cyclodextrin carriers.

Cytotoxic, antioxidant and antibacterial activities of Varthemia iphionoides Boiss. extracts

The hexane, ethyl acetate, chloroform, ethanol and water extracts of aerial parts of Varthemia, Varthemia iphionoides, were investigated for cytotoxic activity against human myelocytic leukemia (HL-60) cells; DPPH radical-scavenging activity; antioxidative activity in the linoleic acid system; reducing power; antibacterial activity; the contents of phenolic compounds. A pronounced cytotoxic effect on human leukemia (HL-60) cells was shown in the hexane, chloroform and ethanol extracts, with inhibition of 89.0, 68.4 and 62.3%, respectively, at a concentration of 200 microg extract/ml. High DPPH radical-scavenging activity, antioxidative activity in the linoleic acid system and reducing power were found in the water and ethanol extracts, and were correlated to the contents of phenolic compounds. Antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Escherichia coli, Bacillus cereus and Salmonella enteritides was shown in the ethyl acetate and chloroform extracts. A compound responsible for the antibacterial activity was isolated from the ethyl acetate extract, and identified as 3-oxocostusic acid.

Potential impact of strawberries on human health: a review of the science

Epidemiological studies have noted a consistent association between the consumption of diets rich in fruits and vegetables and a lower risk for chronic diseases including cancer and cardiovascular disease. There is accumulating evidence that much of the health-promoting potential of these plant foods may come from phytochemicals, bioactive compounds not designated as traditional nutrients. In strawberries, the most abundant of these are ellagic acid, and certain flavonoids: anthocyanin, catechin, quercetin and kaempferol. These compounds in strawberries have potent antioxidant power. Antioxidants help lower risk of cardiovascular events by inhibition of LDL-cholesterol oxidation, promotion of plaque stability, improved vascular endothelial function, and decreased tendency for thrombosis. Furthermore, strawberry extracts have been shown to inhibit COX enzymes in vitro, which would modulate the inflammatory process. Individual compounds in strawberries have demonstrated anticancer activity in several different experimental systems, blocking initiation of carcinogenesis, and suppressing progression and proliferation of tumors. Preliminary animal studies have indicated that diets rich in strawberries may also have the potential to provide benefits to the aging brain.

Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry

HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.

Study of freeze-dried quercetin-cyclodextrin binary systems by DSC, FT-IR, X-ray diffraction and SEM analysis

The inclusion behavior of 2-hydroxypropyl beta-cyclodextrin (HPbetaCD) and beta-cyclodextrin (betaCD), in solution and solid-state was studied towards a poorly water-soluble bioflavonoid, quercetin (QURC), chemically 3,3',4',5',7-pentahydroxy flavone. Drug-cyclodextrin solid systems were prepared by freeze-drying. Phase solubility study was used to evaluate the complexation in solution, of two cyclodextrins, i.e., betaCD and HPbetaCD. The stoichiometry and stability constants of QURC-betaCD (1:1 and 402M(-1)) and QURC-HPbetaCD (1:1 and 532M(-1)) complexes were calculated by phase solubility method. The formation of inclusion complexes with betaCD and HPbetaCD in the solid-state were confirmed by infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy (SEM).

Disruption of the estrogen receptor beta gene in mice causes myeloproliferative disease resembling chronic myeloid leukemia with lymphoid blast crisis

Proliferation of pluripotent, bone marrow stem cells, which develop to lymphoid and myeloid progenitors, is negatively regulated by estrogen. Although in estrogen deficiency and in estrogen receptor knockout mice there is significant alteration in bone marrow hematopoiesis, the effects of aging on estrogen receptor deficiencies in mice have not been investigated yet. In this study we show that by 1.5 years of age, estrogen receptor beta knockout (ERbeta-/-) mice develop pronounced splenomegaly that is much more severe in females than in males. Further characterization of these mice revealed myelogenous hyperplasia in bone marrow, an increase in the number of granulocytes and B lymphocytes in blood, lymphadenopathy, and infiltration of leukocytes in the liver and lung. Analysis by flow cytometry of the bone marrow cells revealed that the percentage and total number of Gr-1hi/Mac-1hi-positive granulocytes were increased by 15-30% and 100%, respectively. The numbers of B cells in the bone marrow and spleen were significantly higher in ERbeta-/- mice than in WT littermates. Some of the ERbeta-/- mice also had a severe lymphoproliferative phenotype. Thus the absence of ERbeta results in a myeloproliferative disease resembling human chronic myeloid leukemia with lymphoid blast crisis. Our results indicate a previously unknown role for ERbeta in regulating the differentiation of pluripotent hematopoietic progenitor cells and suggest that the ERbeta-/- mouse is a potential model for myeloid and lymphoid leukemia. Furthermore, we suggest that ERbeta agonists might have clinical value in the treatment of leukemia.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

Estrogenic and antiproliferative activities of isoliquiritigenin in MCF7 breast cancer cells

Licorice root contains chemically diverse compounds that exhibit estrogenic effects in vitro and in vivo. The chalcone isoliquiritigenin (ISL) is a component of licorice extract exhibiting either antitumorigenic activity or estrogen receptor (ER) alpha-dependent growth promoting effects on breast cancer cells. In order to contribute to a better understanding of this apparent paradox, we synthesized and ascertained the estrogenic properties of ISL using, as model systems, the hormone-sensitive MCF7 breast cancer cells and the steroid-independent HeLa cells. Transfection experiments reveal that ISL is able to transactivate the endogenous ER alpha in MCF7 cells and this is supported by the capability to induce down-regulation of ER alpha protein levels and up-regulation of pS2 mRNA. Moreover, by using chimeric proteins consisting of the hormone binding domains of ER alpha and ER beta fused to the Gal4 DNA binding domain, we have determined that ISL is an estrogenic agonist of both ER isoforms. As a biological counterpart, low and intermediate ISL concentrations that induce substantial transcriptional activity stimulate the proliferation of MCF7 cells. However, high levels of ISL become cytotoxic even in steroid-receptor negative HeLa cells. Thus, the activity of ISL and the balance between risk or chemopreventive factor for estrogen-dependent breast cancer may depend on dietary intake.

Effects of several flavonoids on the growth of B16F10 and SK-MEL-1 melanoma cell lines: relationship between structure and activity

Although flavonoids seem to be capable of acting at all stages of the carcinogenic process, little information is available on their action in melanoma cell lines. The aim of this study was to assess the response of B16F10 and SK-MEL-1 melanoma cell lines to treatment with six different flavonoids after 24 and 72 h of exposure and to relate the response to their structure. We then compared the findings with those for melphalan treatment. When cultures were treated for 24 h, only slight inhibition at the highest concentrations (25 and 50 microM) of tangeretin and luteolin were observed, whereas melphalan caused a dose-related inhibition of growth at all concentrations. Quercetin, hesperetin, 7,3'-dimethylhesperetin and eriodictyol did not produce any effect at 24 h on B16F10 or SK-MEL-1 cells, results which point to the low toxicity of flavonoids. After 72 h of exposure culture growth was inhibited by 7,3'-dimethylhesperetin at 50 microM, but lower concentrations had no effect. Tangeretin was the most effective of the flavonoids in inhibiting B16F10 and SK-MEL-1 cell growth, showing a clear dose-response curve after 72 h. These results suggest that the absence of the C2-C3 double bond on hydroxylated flavonoids results in a loss of effect on both the cell lines, while the higher activity of tangeretin compared with 7,3'-dimethylhesperetin suggests that the presence of at least three adjacent methoxyl groups confers a more potent antiproliferative effect.

Dietary antioxidants during cancer chemotherapy: impact on chemotherapeutic effectiveness and development of side effects

Several studies suggest that dietary supplementation with antioxidants can influence the response to chemotherapy as well as the development of adverse side effects that results from treatment with antineoplastic agents. Administration of antineoplastic agents results in oxidative stress, i.e., the production of free radicals and other reactive oxygen species (ROS). Oxidative stress reduces the rate of cell proliferation, and that occurring during chemotherapy may interfere with the cytotoxic effects of antineoplastic drugs, which depend on rapid proliferation of cancer cells for optimal activity. Antioxidants detoxify ROS and may enhance the anticancer effects of chemotherapy. For some supplements, activities beyond their antioxidant properties, such as inhibition of topoisomerase II or protein tyrosine kinases, may also contribute. ROS cause or contribute to certain side effects that are common to many anticancer drugs, such as gastrointestinal toxicity and mutagenesis. ROS also contribute to side effects that occur only with individual agents, such as doxorubicin-induced cardiotoxicity, cisplatin-induced nephrotoxicity, and bleomycin-induced pulmonary fibrosis. Antioxidants can reduce or prevent many of these side effects, and for some supplements the protective effect results from activities other than their antioxidant properties. Certain side effects, however, such as alopecia and myelosuppression, are not prevented by antioxidants, and agents that interfere with these side effects may also interfere with the anticancer effects of chemotherapy.

Up-regulation of steroid sulphatase activity in HL60 promyelocytic cells by retinoids and 1alpha,25-dihydroxyvitamin D3

HL60 promyeloid cells express both classes of oestrogen receptor (ERalpha and ERbeta). We show that hydrolysis of oestrone sulphate by steroid sulphatase is a major source of oestrone in HL60 cells, and that most of the released oestrone is not metabolized further to 17beta-oestradiol. Treatment of HL60 cells with retinoids or 1alpha,25-dihydroxyvitamin D3 increased steroid sulphatase mRNA and activity in parallel with the induction of CD11b, an early marker of myeloid differentiation that is expressed before the differentiating cells stop proliferating. Use of agonists and antagonists against retinoid receptor-alpha and retinoid receptor-X revealed that both classes of retinoid receptor can drive steroid sulphatase up-regulation. Steroid sulphatase activity fluctuates during the cell cycle, being highest around the transition from G1 to S phase. During the differentiation of HL60 cells induced by all-trans-retinoic acid or 1alpha,25-dihydroxyvitamin D3, there is increased conversion of 17beta-oestradiol into oestrone by an oxidative 17beta-hydroxysteroid dehydrogenase. Treatment of Caco-2 colon adenocarcinoma cells with all-trans-retinoic acid or 1alpha,25-dihydroxyvitamin D3 also increases 17beta-oestradiol oxidation to oestrone. An increase in local oestrone production therefore occurs in multiple cell types following treatment with retinoids and 1alpha,25-dihydroxyvitamin D3. The possible involvement of locally produced oestrogenic steroids in regulating the proliferation and differentiation of myeloid cells is discussed.

Estrogen and microglia: A regulatory system that affects the brain

Sex hormones are involved in the physiological regulation of several aspects of behavior and neuroendocrine events. It has been accepted that such effects are mediated directly by steroid actions on neurons; however, new studies have shown that the glial cells are also affected by gonadal steroids. The microglia are one specialized brain glial cell type, which is a target for estrogen actions. In fact, we believe that many of the immune and nonimmune regulatory functions of microglia in the brain are influenced directly by estrogen via expression and secretion of cytokines, and growth factors by the microglia. The present review details only a section of the known aspects of microglial function, focusing mainly on nonimmune regulatory actions in the brain and their functional relationship with sex hormones. Moreover, we present evidence for the presence of estrogen receptor-beta (ERbeta) in rat microglial cells.

The two phyto-oestrogens genistein and quercetin exert different effects on oestrogen receptor function

We compared the oestrogenic and anti-oestrogenic properties of the two well-known phyto-oestrogens, genistein and quercetin, on the oestrogen-sensitive breast cancer cell line MCF-7. Genistein exerted a biphasic effect on growth of MCF-7 cells, stimulating at low and inhibiting at high concentrations, whereas quercetin was only growth inhibitory. At doses which did not inhibit cell growth, respectively 5 and 1 microM, genistein and quercetin counteracted oestrogen- and transforming growth factor-alpha-promoted cell growth stimulation. Furthermore, genistein promoted transcription of the oestrogen-regulated genes pS2 and cathepsin-D, whereas quercetin interfered with the oestrogen-induced expression of the proteins. In in vitro binding experiments, genistein competed with oestradiol for binding to the oestrogen receptor (ER), but quercetin did not. Quercetin and genistein down-regulated cytoplasmic ER levels and promoted a tighter nuclear association of the ER, but only genistein was able to up-regulate progesterone receptor protein levels. In gel mobility assays, ER preincubation with oestradiol or with the two phyto-oestrogens led to the appearance of the same retarded band, excluding differences between the various complexes in binding to the consensus sequence. The data allowed us to conclude that quercetin acts like a pure anti-oestrogen, whereas genistein displays mixed agonist/antagonist properties, and to formulate a hypothesis on the possible mechanism of action of such phyto-oestrogens.

Estrone potentiates myeloid cell differentiation: a role for 17 beta-hydroxysteroid dehydrogenase in modulating hemopoiesis

Hormones such as 1 alpha, 25-dihydroxy vitamin D3 (D3), all-trans retinoic acid, and 9-cis retinoic acid stimulate differentiation of myeloid progenitor cells via their interaction with specific hormone receptors. However, the sensitivity of cells to these agents is not merely governed by the expression of their receptors and the availability of ligand to bind them. Recent studies from our group suggested that the actions of D3 and retinoids on myelopoiesis also are influenced by endogenous mechanisms involving other steroid hormones. In this study we examined the influence of local estrogen metabolism on the differentiation of HL60 cells and normal primitive myeloid progenitor cells. Quantitative thin-layer chromatography (TLC) analyses showed that HL60 and normal cells are able to generate estrone (E1) from estradiol (E2). Neither cell population generated significant amounts of E2 from E1. Reverse transcriptase polymerase chain reaction and Northern analyses confirmed that normal and leukemic myeloid progenitor cells expressed mRNA for the type I and IV isoforms of 17 beta-hydroxysteroid dehydrogenase. Conversion of E2 to E1 was upregulated within 24 hours when HL60 cells were treated with either all-trans retinoic acid or D3 at doses that induce their differentiation toward neutrophils or monocytes, respectively. Similarly, D3-induced monocyte differentiation of normal myeloid progenitor cells was associated with increased capacity to generate E1 from E2. When HL60 cells or normal myeloid progenitor cells were exposed to exogenous E1 they became more sensitive to the differentiation-inducing effects of D3. Data presented provide further evidence for the local modulation of myelopoiesis by intracrine mechanisms. In particular, our findings suggest that local metabolism of steroids by normal as well as leukemic myeloid cells influences their responsiveness to D3 and retinoids.

Effects of two sex steroids (17beta estradiol and testosterone) on proliferation and clonal growth of the human monoblastic leukemia cell line, U937

We investigated the effects of two sex steroids (17beta estradiol and testosterone) on five human leukemia cell lines. We observed a statistically significant inhibition of proliferation, dose and time dependent, of the human monoblastic leukemia cell line U937. This inhibition was associated with a dose dependent decrease in the number of CFU-blasts in clonogenic cultures. Cytostatic effect was obtained with doses of 5 microM for estrogen and 10 microM for androgen and was not due to a non-specific cytotoxic effect, some cell viability remained high (> 90%) even after 6 days of incubation. More accurately, we demonstrated that growth inhibition was associated with a cell cycle arrest, U937 cells accumulating in G2/M phase. This blockade was dose related with a maximum number of cells accumulating at day 4. Sensitivity of these cells to an S-phase specific agent (hydroxyurea) was not increased, suggesting that these cells were blocked in G2/M and did not undergo mitosis. Expression in U937 cells of high affinity nuclear receptors for estrogen and androgen was negative which was in favour of a type II estrogen binding site, mediated mechanism. Moreover, a small fraction of these cells underwent apoptosis or differentiation with about 12% apoptotic cells and a significant increase (more than 30%) of two myelomonocytic markers (CD13 and CD64). These results demonstrate that the proliferation of some leukemic cells may be inhibited by micromolar concentrations of sex steroids, independently of nuclear receptor expression. The main mechanism seems to be a block in cell cycle associated with modulation of apoptosis and differentiation. It provided additional evidence for the potential value of sex steroids and their analogues in the treatment of leukemias.

Determination of quercetin in human plasma by HPLC with spectrophotometric or electrochemical detection

A reversed-phase high-performance liquid chromatographic method for the determination of quercetin in human plasma following intravenous infusion is described. Quercetin in plasma was extracted with methanol-dimethyl sulphoxide (4:1 v/v) and separated on a C18 Hypersil-BDS column with 44% (v/v) methanol in 0.1 M ammonium acetate (pH 5.15) containing 0.27 mM EDTA as the mobile phase. The drug was detected specifically and sensitively at its absorption maximum of 375 nm, or electrochemically, with a detection limit of 80 ng/mL and 2 ng/mL, respectively.

Studies on the inhibitory effects of quercetin on the growth of HL-60 leukemia cells

Quercetin, a naturally occurring flavonoid, has been shown to exert multiple pharmacological effects and to be an anticancer agent or a supplementary anticancer agent. In this report, the human HL-60 promyelocytic leukemia cell line was used to study the effects of quercetin on the growth, cell cycle, activities of cytosolic and membrane protein kinase C (PKC) and tyrosine protein kinase (TPK), and phosphoinositide production of the tumor cells. The results showed that quercetin inhibited the growth of HL-60 cells in a concentration-dependent manner, with an IC50 value of about 7.7 microM after 96 hr of treatment; when the concentration of quercetin was 10 microM, the percent inhibition on the growth of HL-60 cells was 17.1, 27.3, 40.1, and 52.7% after 24, 48, 72, and 96 hr of treatment, respectively. Flow cytometric analyses showed that quercetin caused an increase in cells in the G2/M phase and a decrease in cells in the G0/G1 phase of the cell cycle in a concentration-dependent manner; these effects were reversed when quercetin was removed from the culture medium. Quercetin strongly inhibited the activities of cytosolic PKC and membrane TPK from HL-60 cells in vitro, with IC50 values of about 30.9 and 20.1 microM, respectively, but did not affect membrane PKC or cytosolic TPK activity from HL-60 cells in vitro. Quercetin markedly inhibited in a concentration-dependent manner the production of phosphoinositides in intact HL-60 cells. The results provide evidence that the inhibitory effect of quercetin on the growth of HL-60 cells may be related to its inhibitory effects on PKC and/or TPK in vitro and/or on the production of phosphoinositides.

Quercetin inhibits heat shock protein induction but not heat shock factor DNA-binding in human breast carcinoma cells

The flavonoid quercetin inhibits the heat-induced synthesis of heat shock proteins (hsps) in a variety of cell lines. To determine whether quercetin could inhibit hsp expression in breast cancer cells, we used the human breast cancer cell line, MDA-MB-231. Treatment of these cells with quercetin decreased the heat-induced synthesis of hsp27 and hsp70. However, inhibition of hsp expression did not correspond with the reduced ability of heat shock transcription factors (HSFs) to bind DNA. Furthermore, while quercetin treatment inhibited HSF2 expression, it only slightly affected HSF1 expression in breast cancer cells. In contrast, quercetin inhibited both HSF DNA-binding activity and HSF expression in HeLa cells. Our studies suggest that quercetin's action is cell-type specific, and in breast cancer cells may involve regulation of HSF transcriptional activity, rather than regulation of its DNA-binding activity.

Quercetin and the growth of leukemic progenitors

The bioflavonoid quercetin (3, 3', 4', 5-7-pentahydroxyflavone) inhibits in a dose-dependent manner the in vitro growth of acute leukemias and enhances the anti-proliferative activity of cytosine arabinoside. Quercetin exerts a blocking action of cell transition from the G0/G1 to the S phase of the cell cycle. Acute myeloid leukemias (AML)-M3,-M4 and -M5, and acute lymphoid leukemias (ALL) were more sensitive to quercetin than AML-M1 and -M2 subtypes. The sensitivity of leukemic progenitors to the growth inhibitory effect of quercetin significantly correlated with their clonogenic efficiency. We postulate that quercetin exerts its growth inhibitory action by interaction with type II estrogen binding sites and subsequent induction of Transforming Growth Factor-beta 1 expression and secretion. Finally quercetin is synergistic with hyperthermia in inducing apoptosis of leukemic cells sparing normal stem cell progenitors. Taken together these results stress the potential role of quercetin in the treatment of acute leukemias and its in vitro use in purging procedures for autologous bone marrow transplantation.

Antiproliferative effect of silybin on gynaecological malignancies: synergism with cisplatin and doxorubicin

The aim of this study was to test the antiproliferative activity of silybin, a flavonoid, on human ovarian and breast cancer cell lines. Since flavonoids are thought to act through Type II oestrogen binding sites (Type II EBS), silybin binding to Type II EBS was also examined. Silybin, used in concentrations from 0.1 to 20 microM, exerted a dose-dependent growth inhibitory effect on OVCA 433, A2780 parental and drug-resistant ovarian cancer cells, and MCF-7 doxorubicin (DOX)-resistant breast cancer cells (IC50 = 4.8-24 microM). Both L and D diastereoisomers of silybin were effective in inhibiting A2780 WT cell growth (IC50 = 14 and 20 microM, respectively). Flow cytometry revealed that silybin decreased the percentage of cells in the S and G2-M phases of the cell cycle with a concomitant increase in cells in the G0-G1 phase. Silybin was able to compete with [3H]E2 for nuclear but not cytosolic Type II EBS. Its affinity parallels its efficacy in inhibiting cell proliferation. Furthermore, silybin (0.1 and 1 microM) potentiates the effect of cisplatin (CDDP) (0.1-1 micrograms/ml) in inhibiting A2780 WT and CDDP-resistant cell growth. Similar results were obtained on MCF-7 DOX-resistant cells when silybin (0.1 microM) was associated with doxorubicin (0.1-10 micrograms/ml). As assessed by the Berembaum isobole method, the effect of silybin-CDDP and silybin-DOX combinations results in a synergistic action. Using the 'stem cell assay' described by Hamburger and Salmon [Science 1977, 197, 461-463], we found that silybin exerted a dose-dependent inhibition of clonogenic efficiency of cells derived from three ovarian tumours (IC50 = 7.4, 4 and 6.4 microM, respectively). Since CDDP and DOX are the two most commonly used drugs for gynaecological tumours, the clinical application of silybin is currently under investigation in our institute.

Inhibition of human breast cancer cell proliferation and delay of mammary tumorigenesis by flavonoids and citrus juices

Two citrus flavonoids, hesperetin and naringenin, found in oranges and grapefruit, respectively, and four noncitrus flavonoids, baicalein, galangin, genistein, and quercetin, were tested singly and in one-to-one combinations for their effects on proliferation and growth of a human breast carcinoma cell line, MDA-MB-435. The concentration at which cell proliferation was inhibited by 50% (IC50), based on incorporation of [3H]thymidine, varied from 5.9 to 140 micrograms/ml for the single flavonoids, with the most potent being baicalein. IC50 values for the one-to-one combinations ranged from 4.7 micrograms/ml (quercetin + hesperetin, quercetin + naringenin) to 22.5 micrograms/ml (naringenin + hesperetin). All the flavonoids showed low cytotoxicity (> 500 micrograms/ml for 50% cell death). Naringenin is present in grapefruit mainly as its glycosylated form, naringin. These compounds, as well as grapefruit and orange juice concentrates, were tested for their ability to inhibit development of mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in female Sprague-Dawley rats. Two experiments were conducted in which groups of 21 rats were fed a semipurified diet containing 5% corn oil and were given a 5-mg dose of DMBA intragastrically at approximately 50 days of age while in diestrus. One week later, individual groups were given double-strength grapefruit juice or orange juice or fed naringin or naringenin at levels comparable to that provided by the grapefruit juice; in the second experiment, the rats were fed a semipurified diet containing 20% corn oil at that time. As expected, rats fed the high-fat diet developed more tumors than rats fed the low-fat diet, but in both experiments tumor development was delayed in the groups given orange juice or fed the naringin-supplemented diet compared with the other three groups. Although tumor incidence and tumor burden (grams of tumor/rat) were somewhat variable in the different groups, rats given orange juice had a smaller tumor burden than controls, although they grew better than any of the other groups. These experiments provide evidence of anticancer properties of orange juice and indicate that citrus flavonoids are effective inhibitors of human breast cancer cell proliferation in vitro, especially when paired with quercetin, which is widely distributed in other foods.

Effects of homo-aza-steroids on acute non-lymphocytic leukaemia cell proliferation in vitro

Homo-aza-steroids (modified steroid molecules) in their esterified forms have been used extensively as carrier molecules of alkylating agents against several neoplastic malignancies in vivo and in vitro. We studied the effects of two homo-aza-steroid carrier molecules alone, namely 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13, 17-lactam (compound 1) and 13 alpha-amino-13,17-seco-1,3,5-estratrien-17-oic- 13,17-lactam (compound 2), on human acute non-lymphocytic leukaemia cell proliferation in vitro. We used peripheral blood samples from 27 untreated ANLL patients (eight M1, four M2, two M3, six M4, three M5a, two M5b and two M6, according to FAB criteria). Proliferative activity was estimated by using thymidine uptake and the percentage of cells in metaphase in 24, 48 and 72 h of culture. Exposure of human leukaemic blasts with either of the two compounds resulted in enhanced cell proliferation in M1, M2, M4, M6 and M5a (only by compound 2) cases, whereas there was no significant effect in the M3 and M5b cases. Our results indicate that the two compounds tested exhibit stimulatory effect on cell proliferation, particularly in blast cells possessing a relatively smaller degree of differentiation (M1 and M6 cases exhibiting CD34 and CD7). Further research is needed to study the cell growth effect and the therapeutic potential of these steroid molecules in human blood malignancies in vitro and in vivo.

Biphasic actions of estrogen on colon cancer cell growth: possible mediation by high- and low-affinity estrogen binding sites

The present experiments were carried out to investigate the possible direct effects of estrogens (E) on the growth of colon cancer cells. Estradiol exhibited a concentration-dependent biphasic growth effect on a mouse colon cancer cell line (MC-26). Low concentrations of estradiol (10(-10) M: to 10(-8) M: ) had a growth-stimulatory effect, while higher concentrations (10(-7) M: to 10(-6) M: ) were growth-inhibitory. Estrogen receptor (ER) mRNA as well as specific, saturable binding of estradiol to ER (K(d)=0.3NM: , B(max)=0.72 fmol/μg DNA) was identified in these cells. In addition to the classical high affinity ER, lower affinity, higher capacity estrogen binding sites (K(d)=35MM: , B(max)=30 fmol/μg DNA) were also characterized in MC-26 cells. These two types of estrogen binding sites exhibited distinct binding specificities for E and antiestrogens. Treatment of MC-26 cells with an oligodeoxy-nucleotide antisense to the translation start codon of ER mRNA did not alter the grown-inhibitory effect of 10(-6) M: estradiol, demonstrating that the growth-inhibitory effect of high concentrations of E was not mediated by ER; we have previously shown that under the same conditions, ER antisense oligonucleotides do block the growth-stimulatory effects of 10(-9) M: E(2) in MC-26 cells. The data suggest that physiological concentrations of estradiol acting via the classical ER may have a proliferative effect on the growth of colon cancer cells. However, in situations where there are high luminal concentrations of estrogenic compounds, they may act on low affinity estrogen binding sites that mediate the growth-inhibitory effect.

Hormonal regulation of nuclear type II estrogen binding sites in the dorsolateral prostate of noble rats

We previously demonstrated that simultaneous treatment of Noble (NBL) rats with estradiol (E2) and testosterone (T) for 16 weeks induces a proliferative response selectively in the dorsolateral prostates (DLP) of all treated animals [1, 2]. The unique sensitivity of rat DLP to the conjoint androgen-estrogen-induced mitogenic action may be attributable to the presence of a moderate affinity, high capacity, nuclear estrogen binder (type II sites) found exclusively in this prostatic lobe [2, 3]. Little is known about whether prostatic type II site levels are under hormonal regulation. The aim of this study is to determine whether testicular steroids play a role in regulating the basal and/or induced levels of type II site expression in rat DLP. In the first experiment, rats were castrated and immediately treated with 5 alpha-dihydrotestosterone (DHT) and/or E2 for 6 weeks to determine whether these steroids, separately or jointly, could sustain DLP type II site levels in castrates. Treatments of castrated rats with DHT and DHT+E2 were found to be effective in maintaining DLP type II site levels and gland wet weights at values close to those found in intact untreated controls, while treatments with E2 failed to maintain these parameters at levels observed in intact animals. In the second experiment, intact rats were treated with an androgen (T or DHT) or E2, alone or in combination, for 16 weeks to ascertain which hormonal regimen could induce a higher level of type II site expression in the DLP. Treatments of rats with an androgen (T or DHT) or E2 alone did not change DLP type II site levels even though T treatment caused a slight increase in gland weight, while E2 treatment induced prostatic atrophy. Contrary to single hormone treatments, combined T + E2 and DHT+E2 treatments were effective in inducing a doubling of type II sites and increases in wet weight of the DLPs. These data indicate that testicular androgen is the primary factor responsible for maintaining a basal level of type II site expression in rat DLP, while conjoint androgenic-estrogenic action is needed for the induction of a higher level of type II site expression in the tissue.

Quercetin exerts a preferential cytotoxic effect on active dividing colon carcinoma HT29 and Caco-2 cells

The effect of the naturally occurring flavonol, quercetin, was investigated on cell growth and metabolism of two human carcinoma cell lines, HT29 and Caco-2 cells, both during the exponentially growing phase and after confluence. Our results show clearly that, after a 48-h period of treatment, quercetin (in the range of concentration from 15 microM to 120 microM) exerted a preferential cytotoxic effect on active proliferating cells. This effect was dose dependent and was accompanied by a simultaneous inhibition of lactate release and a dramatic decrease of total cellular ATP content. In contrast, in confluent cells, quercetin failed to affect cell viability or lactate release, but led nevertheless to a depletion of cellular ATP level. In conclusion, the cytotoxicity of quercetin is markedly higher in actively growing cells in comparison with confluent cells.

Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target

This study demonstrates that the flavonoid quercetin (Q), a plant-derived compound with low toxicity in vivo, greatly potentiates the growth-inhibitory activity of Adriamycin (ADR) on MCF-7 ADR-resistant human breast cancer cells. The effect of Q was dose-dependent at concentrations ranging between 1 and 10 microM. Since ADR resistance in these cells is associated with the expression of high levels of P-glycoprotein (Pgp), we evaluated the effect of Q and related flavonoids of Pgp activity in cytofluorographic efflux experiments with the fluorescent dye rhodamine 123 (Rh 123). Our results indicate that Q and 3-OMe Q (3',4',7-trimethoxyquercetin) but not the 3-rhamnosylglucoside of Q (rutin) inhibit the Pgp pump-efflux activity in a dose-related manner. Moreover, 10 microM Q reduces the expression of the immunoreactive Pgp in MCF-7 ADR-resistant cells as evaluated by cytofluorimetric assay. In conclusion, these findings provide a further biological basis for the potential therapeutic application of Q as an anti-cancer drug either alone or in combination with ADR in multidrug-resistant breast tumor cells.