Growth-inhibitory effect of tamoxifen and quercetin and presence of type II estrogen binding sites in human laryngeal cancer cell lines and primary laryngeal tumors

Laryngeal Cancer Cells Metabolize 25-Hydroxyvitamin D3 and Respond to 24R,25-dihydroxyvitamin D3 via a Mechanism Dependent on Estrogen Receptor Levels

Studies have evaluated vitamin D3's therapeutic potential in estrogen-responsive cancers, with conflicting findings. We have shown that the proliferation of breast cancer cells is regulated by 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) depending on estrogen receptor alpha 66 (ERα66) expression, suggesting that this could also be the case for estrogen-sensitive laryngeal cancer cells. Accordingly, we examined levels of ERα isoforms in ERα66-positive UM-SCC-12 and ERα66-negative UM-SCC-11A cells and their response to 24R,25(OH)2D3. 24R,25(OH)2D3 stimulated proliferation, increased the expression of metastatic markers, and inhibited apoptosis in UM-SCC-12 cells while having the opposite effect in UM-SCC-11A cells. To evaluate if vitamin metabolites could act via autocrine/paracrine mechanisms, we assessed the expression, protein levels, and activity of vitamin D3 hydroxylases CYP24A1 and CYP27B1. Both cell types expressed both mRNAs; but the levels of the enzymes and their activities were differentially regulated by estrogen. ERα66-negative UM-SCC-11A cells produced more 24,25(OH)2D3 than UM-SCC-12 cells, but comparable levels of 1,25(OH)2D3 when treated with 25(OH)D3 These results suggest that the regulation of vitamin D3 metabolism in laryngeal cancer cells is modulated by ERα66 expression, and support a role for 24R,25(OH)2D3 as an autocrine/paracrine regulator of laryngeal cancer. The local metabolism of 25(OH)D3 should be considered when determining the potential of vitamin D3 in laryngeal cancer.

The impact of tamoxifen treatment on voice parameters in premenopausal women with breast cancer

OBJECTIVE

The study aims to investigate the estrogen-agonistic effects of tamoxifen on voice parameters in premenopausal women diagnosed with breast cancer.

METHODS

A total of 108 premenopausal women were included, segmented into distinct treatment groups and a control group. Objective sound analysis was conducted using robust statistical methods, employing SPSS 25.0 for data analysis.

RESULTS

The study identified a statistically significant reduction in Jitter values across all treatment groups compared to the control group. No significant changes were observed in other voice quality parameters such as F0, Shimmer, NHR, and HNR.

CONCLUSIONS

The findings suggest that tamoxifen may have an estrogen-agonistic effect on voice quality, thereby potentially influencing future treatment protocols. This research fills a critical void in existing literature and sets the stage for more comprehensive studies that consider affects of hormonal therapies to voice.

The Impact of Natural Dietary Compounds and Food-Borne Mycotoxins on DNA Methylation and Cancer

Cancer initiation and progression is an accumulation of genetic and epigenetic modifications. DNA methylation is a common epigenetic modification that regulates gene expression, and aberrant DNA methylation patterns are considered a hallmark of cancer. The human diet is a source of micronutrients, bioactive molecules, and mycotoxins that have the ability to alter DNA methylation patterns and are thus a contributing factor for both the prevention and onset of cancer. Micronutrients such as betaine, choline, folate, and methionine serve as cofactors or methyl donors for one-carbon metabolism and other DNA methylation reactions. Dietary bioactive compounds such as curcumin, epigallocatechin-3-gallate, genistein, quercetin, resveratrol, and sulforaphane reactivate essential tumor suppressor genes by reversing aberrant DNA methylation patterns, and therefore, they have shown potential against various cancers. In contrast, fungi-contaminated agricultural foods are a source of potent mycotoxins that induce carcinogenesis. In this review, we summarize the existing literature on dietary micronutrients, bioactive compounds, and food-borne mycotoxins that affect DNA methylation patterns and identify their potential in the onset and treatment of cancer.

Does tamoxifen have a therapeutic role outside of breast cancer? A systematic review of the evidence

INTRODUCTION

Tamoxifen is a widely used hormonal based therapy for breast cancer in the adjuvant and metastatic setting, prolonging overall and recurrence-free survival. There has been increasing interest in the potential for novel "off-target" effects of tamoxifen and its metabolite N-desmethyltamoxifen across a number of cancer types. We aim to review the current literature regarding the potential use of tamoxifen in other primary malignancies.

METHOD

A qualitative systematic review was performed according to the PRISMA guidelines using pre-set search criteria across the PubMed, Cochrane and Scopus databases from 1985 to 2019. Additional results were generated from included papers references.

RESULTS

A total of 324 papers were identified, of which 47 were included; a further 29 articles were obtained from additional referencing to give a total of 76 articles. Clinical trials have demonstrated benefits with the use of tamoxifen in isolation and combination, specifically in patients with advanced non-resectable malignancy, however results are not consistent across the literature. In vivo data consistently suggests that off target effects of tamoxifen are mediated through the ceramide pathway or through inhibition of protein kinase C (PKC).

CONCLUSIONS

With increased focus upon the potential of repurposing drugs, tamoxifen may be a candidate for repurposing in the wider cancer setting. There is evidence to suggest that the ceramide or PKC pathway could act as a therapeutic target for tamoxifen or alternative chemotherapeutics and merits further investigation.

Estradiol receptor profile and estrogen responsiveness in laryngeal cancer and clinical outcomes

There is growing evidence that laryngeal cancers are responsive to sex hormones, specifically 17β-estradiol (E₂), despite controversy regarding the presence and characterization of E₂ receptors (ER). Determination of sex hormone responsiveness impacts the prognosis of laryngeal cancer patients and the treatment modalities implemented by their clinicians. Discovery of membrane-associated steroid hormone receptors and rapid membrane signaling opened the possibility that cancers previously labeled 'non-hormone dependent' and 'ER negative' might in fact be susceptible to the effects of E₂ via these membrane receptors. ERα66 and ERβ, the classical nuclear receptors, are present in the membranes of different cancer cells via a mechanism referred to as trafficking. Novel splice variants of these traditional receptors, a key example being ERα36, have also been found in the caveolae of cancer cells. Previous work demonstrated that ERα36 has a role in the tumorigenesis of laryngeal cancer, enhancing both proliferation and the anti-apoptotic effect of E₂ against chemotherapeutics. The present study showed that expression of different membrane ERs in laryngeal cancer is not uniform, which may result in differential and even antagonistic responses to E₂. E₂ had protective or deleterious effects in different cancer cell lines, stimulating proliferation and conferring anti-apoptotic potential to the cancer cells according to their receptor profile. These findings stress the importance of establishing the molecular and clinical characterization of the specific laryngeal tumor in order to tailor treatment accordingly, thus optimizing care while reducing adverse effects for individual patients.

Site-specific anticancer effects of dietary flavonoid quercetin

Food-derived flavonoid quercetin, widely distributed in onions, apples, and tea, is able to inhibit growth of various cancer cells indicating that this compound can be considered as a good candidate for anticancer therapy. Although the exact mechanism of this action is not thoroughly understood, behaving as antioxidant and/or prooxidant as well as modulating different intracellular signalling cascades may all play a certain role. Such inhibitory activity of quercetin has been shown to depend first of all on cell lines and cancer types; however, no comprehensive site-specific analysis of this effect has been published. In this review article, cytotoxicity constants of quercetin measured in various human malignant cell lines of different origin were compiled from literature and a clear cancer selective action was demonstrated. The most sensitive malignant sites for quercetin revealed to be cancers of blood, brain, lung, uterine, and salivary gland as well as melanoma whereas cytotoxic activity was higher in more aggressive cells compared to the slowly growing cells showing that the most harmful cells for the organism are probably targeted. More research is needed to overcome the issues of poor water solubility and relatively low bioavailability of quercetin as the major obstacles limiting its clinical use.

17Beta-estradiol promotes aggressive laryngeal cancer through membrane-associated estrogen receptor-alpha 36

17β-estradiol (E2) plays a key role in tumorigenesis by enhancing cell survivability and metastasis through its cytoplasmic receptors. Recently, a variant of estrogen receptor alpha, ERα36 has been implicated as a substantial mediator of E2's proliferative and antiapoptotic effects through rapid membrane-associated signaling, and cancers previously regarded as hormone-independent due to the absence of traditional receptors, may in fact be susceptible to E2. Despite rising from a secondary sex organ and having a clear gender disposition, laryngeal cancer is not uniformly accepted as hormone dependent, even in the face of compelling evidence of E2 responsiveness. The aim of this study was to further elucidate the role of E2 in the tumorigenesis of laryngeal cancer, both in vitro and in vivo. ERα36 presence was evaluated in membranes of the laryngeal carcinoma cell line, Hep2, as well as in laryngeal tumor samples. In vitro ERα36 was found to mediate rapid activation of protein kinase C and phospholipase D by E2, leading to increased proliferation and protection against chemotherapy-induced apoptosis. Furthermore, in response to E2 activation of ERα36, an upregulation of angiogenic and metastatic factors was observed. Clinical analysis of laryngeal tumors revealed a similar association between the amount of ERα36 and VEGF and indicated a role in lymph node metastasis. These findings present compelling evidence of ERα36-dependent E2 signaling in laryngeal cancer. Thus, targeting ERα36 may reduce the deleterious effects of E2 in laryngeal cancer, ultimately suggesting the importance of antiestrogen therapy or the production of novel drugs that specifically target ERα36.

Anticancer effect and mechanism of polymer micelle-encapsulated quercetin on ovarian cancer

Encapsulation of hydrophobic agents in polymer micelles can improve the water solubility of cargos, contributing to develop novel drugs. Quercetin (QU) is a hydrophobic agent with potential anticancer activity. In this work, we encapsulated QU into biodegradable monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles and tried to provide proof-of-principle for treating ovarian cancer with this nano-formulation of quercetin. These QU loaded MPEG-PCL (QU/MPEG-PCL) micelles with drug loading of 6.9% had a mean particle size of 36 nm, rendering the complete dispersion of quercetin in water. QU inhibited the growth of A2780S ovarian cancer cells on a dose dependent manner in vitro. Intravenous administration of QU/MPEG-PCL micelles significantly suppressed the growth of established xenograft A2780S ovarian tumors through causing cancer cell apoptosis and inhibiting angiogenesis in vivo. Furthermore, the anticancer activity of quercetin on ovarian cancer cells was studied in vitro. Quercetin treatment induced the apoptosis of A2780S cells associated with activating caspase-3 and caspase-9. MCL-1 downregulation, Bcl-2 downregulation, Bax upregulation and mitochondrial transmembrane potential change were observed, suggesting that quercetin may induce apoptosis of A2780S cells through the mitochondrial apoptotic pathway. Otherwise, quercetin treatment decreased phosphorylated p44/42 mitogen-activated protein kinase and phosphorylated Akt, contributing to inhibition of A2780S cell proliferation. Our data suggested that QU/MPEG-PCL micelles were a novel nano-formulation of quercetin with a potential clinical application in ovarian cancer therapy.

The investigation of effects of quercetin and its combination with Cisplatin on malignant mesothelioma cells in vitro

Malignant Mesothelioma (MM) is an aggressive and lethal tumour of the serosal surfaces with poor prognosis. In this study, we have investigated the antiproliferative effect of Quercetin (QU) and its combination with Cisplatin (CIS) on SPC212 and SPC111 cell lines. Our experiments showed that QU significantly reduced the proliferation of cell lines, altered the cell cycle distribution, and increased the level of Caspase 9 (C9) and Caspase 3 (C3) in concentration and time-dependent manner. Additionally, the combination of QU + CIS was found more effective when compared with individual treatment of agents.

Quercetin inhibits lymphocyte activation and proliferation without inducing apoptosis in peripheral mononuclear cells

Toxicity of chemotherapeutic drugs towards normal cells is a serious side effect of cancer treatment. Thus, finding of molecules with low toxicity for normal cells is crucial. Several natural compounds, such as flavonoid quercertin, are receiving a growing attention as "chemopreventers". Quercetin kills tumour-derived cell lines, but little is known about its effects on normal cells. Here we show that although quercetin exerts a higher apoptotic potential on leukemic cell lines than on peripheral blood mononuclear cells (PBMCs) and does not sensitize PBMCs to CD95-induced apoptosis, it is able to inhibit normal immune functions such as T cell proliferation and activation. Quercetin sensitivity is independent on cell cycle progression since it was not abrogated in serum-starved U937 cells, nor proliferating PBMCs underwent apoptosis after quercetin treatment. However, quercetin prevented PHA-induced PBMC proliferation and SEB-induced upregulation of activation markers. Our data suggest that quercetin, while incapable of inducing apoptosis in normal cells under several conditions, could interfere with effector T cell function.

Should there be more molecular staging of head and neck cancer to improve the choice of treatments and thereby improve survival?

PURPOSE OF REVIEW

Overall survival of head and neck squamous cell carcinoma patients on the whole has not dramatically improved in the last 30 years. One of the reasons is that tumour, node, metastasis classification is probably in some cases inadequate, since similar cases under a clinico-pathological point of view, may differ widely in prognosis. The most important reason for this is probably the extreme biological heterogeneity, which leads to a lack of consistency in treatment planning. The aim of the present review is to delineate the advances and the perspectives of clinical use of molecular characterization, which is an attempt to break through such molecular heterogeneity and to define, together with tumour, node, metastasis classification, homogeneous groups of patients for prognostic stratification and treatment selection.

RECENT FINDINGS

Among the markers evaluated in the last years, some have revealed particular promise. Epidermal growth factor receptor is probably the most reliable molecular marker at present, retaining its prognostic value independently from primary treatment. The p53 gene, the p53 protein being the main effector of DNA damage induced apoptosis, is probably the best predictor of radio/chemosensitivity.

SUMMARY

Even if clinical tumour, node, metastasis classification will probably retain its significance, it is now becoming possible, by molecular markers, to acquire biological information about host and tumour, to break through the above-cited molecular heterogeneity and eventually to optimize the choice of treatment.

Human parathyroid hormone-related protein and human parathyroid hormone receptor type 1 are expressed in human medulloblastomas and regulate cell proliferation and apoptosis in medulloblastoma-derived cell lines

Human parathyroid hormone-related protein (hPTHrP), identified in patients with paraneoplastic hypercalcemia and expressed by different cell types during development and adult life, plays important roles in many human neoplasms. Immunohistochemical and RT-PCR analyses of hPTHrP and human parathyroid hormone receptor type 1 (PTHR-1) in primary medulloblastoma confirmed their expression in both classic and desmoplastic variants at RNA and protein levels. To evaluate the functional role of hPTHrP, DAOY and D283 medulloblastoma and U87MG glioma cells, expressing high levels of hPTHrP and PTHR-1, were treated with anti-sense oligonucleotides for hPTHrP. Anti-sense treatment produced in all cell lines a decrease of cell proliferation and clonogenic activity and an increase of apoptosis, while addition of exogenous hPTHrP (1-37) prevented these effects. Anti-sense induced the increase of Caspase-3, Fas (CD95) mRNAs and Bax/Bcl-2 mRNA ratio after 12 h of cell treatment. Exogenous hPTHrP (1-37) increased intracellular Ca(2+) concentration in DAOY cells as revealed by FURA. Anti-sense treated cells showed a significant decrease of steady-state levels of intracellular Ca(2+), which was reverted by addition of exogenous hPTHrP (1-37). This study indicates that hPTHrP and PTHR-1 are expressed in medulloblastoma and could promote tumor growth, protecting cells from apoptosis.

Treatment of mcf-7 breast cancer cells with a red grape wine polyphenol fraction results in disruption of calcium homeostasis and cell cycle arrest causing selective cytotoxicity

Food components influence the physiology by modulating gene expression and biochemical pathways within the human body. The disease-preventive roles of several fruit and vegetable components have been related to such properties. Polyphenolic components such as flavonoids are strong antioxidants and induce the expression of several xenobiotic-detoxifying enzymes. The mechanism of selective cytotoxicity induced by red grape wine polyphenols against MCF-7 breast cancer cells was investigated in relation to their interference with calcium homeostasis. MCF-7 cells showed an increase in cytosolic calcium levels within 10 min of treatment with the polyphenols. Immunohistochemical localization of calmodulin with secondary gold-labeled antibodies showed similar levels of gold labeling in both MCF-7 cells and the spontaneously immortalized, normal MCF-10A cell line. MCF-7 cells treated with the red wine polyphenol fraction (RWPF) showed swelling of endoplasmic reticulum, dissolution of the nucleus, and loss of plasma membrane integrity as well as reduced mitochondrial membrane potential. These cells were arrested at the G2/M interphase. By contrast, MCF-10A cells did not show such changes after RWPF treatment. The results suggest that polyphenol-induced calcium release may disrupt mitochondrial function and cause membrane damage, resulting in selective cytotoxicity toward MCF-7 cells. This property could further be developed toward breast cancer prevention strategies either independently or in conjunction with conventional prevention therapies where a positive drug-nutrient interaction can be demonstrated.

Quercetin inhibits eNOS, microtubule polymerization, and mitotic progression in bovine aortic endothelial cells

Quercetin (QRN), one of the most abundant flavonoids in the human diet, is a known antioxidant and inhibitor of cancer cell cycle progression. Here, we provide the first evidence that QRN inhibits angiogenesis via a mechanism involving both suppression of endothelial nitric oxide synthase (eNOS) and early M-phase cell cycle arrest. Bovine aortic endothelial (BAE) cells were exposed to doses of up to 100 micromol/L QRN and assayed for eNOS activity and phosphorylation status. Phosphorylation of eNOS at Ser 617 (bovine sequence) is thought to occur in response to Akt stimulation and to be required for eNOS activity. Together with basal eNOS activity, eNOS phosphorylation at Ser 617 and Akt Ser 473 phosphorylation were dose dependently and concomitantly suppressed by QRN within 30 min. Furthermore, although the significant (P < 0.05) inhibitory effect of a single 100 micromol/L QRN dose on eNOS activity was overcome within approximately 24 h, chronic QRN exposures (24-48 h) led to early M-phase arrest and disruption of mitotic microtubule polymerization. In vivo, QRN administered i.p. to female Balb/C mice bearing both syngeneic mammary tumors and Matrigel implants suppressed angiogenesis as measured by endothelial cell immunohistochemistry and hemoglobin concentration. Taken together, these findings suggest a dual mechanism by which QRN suppresses endothelial cell proliferation, both acutely via inhibition of eNOS Ser 617 phosphorylation, and chronically via perturbation of mitotic microtubule polymerization. This novel mechanism of QRN in endothelial cells may in part explain its inhibitory action on angiogenesis and further discern a potential role of QRN as a chemopreventive agent.

Antitumor activity of some natural flavonoids and synthetic derivatives on various human and murine cancer cell lines

The effect of various natural flavonoids, cinnamic acid derivatives, and a series of synthetic flavones on cell proliferation was evaluated in vitro in a panel of established human and murine tumor cell lines. The most potent antiproliferative agents were caffeic acid n-butyl ester (12) > 2'-nitroflavone (26) > caffeic acid ethyl ester (11) approximately = 2',6-dinitroflavone (27) > apigenin (3) > 3'-bromoflavone (20) approximately = 2'-fluoro-6-bromoflavone (31). Some compounds showed a moderate effect, the order of cytotoxic activities being chrysin (2) > 2'-fluoro-6-chloroflavone (30) approximately = 2'-chlorochrysin (32) > alpha-naphthoflavone (7) > beta-naphthoflavone (8) approximately = 6-chloroflavone (14) approximately = 6-bromoflavone (15) approximately = 4'-nitroflavone (23). A structure-activity relationship analysis of each group of compounds was performed. None of the natural or synthetic compounds tested affected the proliferation of epithelial cells derived from normal mammary gland of mice or fibroblastic cells from mouse embryo, suggesting a selective action against tumor cells.

Molecular markers in laryngeal squamous cell carcinoma: towards an integrated clinicobiological approach

Of the most frequent malignancies in the United States, cancers of the larynx and of the uterine corpus are the only ones not to show an increase in 5-year survival rates over the last 30 years. The increasing use of chemo- and radiotherapy and conservative surgery to preserve organs and their functions has probably led to a better quality of life in patients with laryngeal cancer, but has definitely failed to improve survival, which remains the primary aim. In our opinion, to reduce laryngeal cancer-related mortality, a change in clinical approach is required. We have reviewed the literature on the potential role of molecular markers in the clinical management of laryngeal cancer. We believe that some of the most significant biological markers might be integrated with the evaluation of behavioural risk factors, clinical TNM staging and histopathological grading for a novel clinicomolecular approach to laryngeal cancer. We foresee the use of the most promising biological markers in the phases of prevention, diagnosis, prognostic assessment and drug design.

The effect of quercetin on pro-apoptotic activity of cisplatin in HeLa cells

It is well known that some tumour cells are very resistant to chemotherapy-induced cell death which indicate poor prognosis for patients. Thus the aim of the present study was to investigate the effect of quercetin on pro-apoptotic activity of cisplatin in human cervix carcinoma cells (HeLa). Three variants of experiments were performed. In the first one cells were incubated with studied drugs separately for 8 and 24h. In the second, drugs were added to the culture medium simultaneously. In third cisplatin or quercetin addition was followed by subsequent quercetin or cisplatin treatment, respectively. We observed different apoptotic effects, dependent on the drug succession. Preincubation of cells with quercetin followed by cisplatin treatment appeared to be the most effective and was correlated with strong activation of caspase-3 and inhibition of both heat shock proteins (Hsp72) and multi-drug resistance proteins (MRP) levels. Our results indicate that quercetin pretreatment sensitizes HeLa cells to cisplatin-induced apoptosis in HeLa cells.

Antiproliferative effects of daucane esters fromFerula communis andF. arrigonii on human colon cancer cell lines

Certain jaesekanadiol p-hydroxy- and p-methoxybenzoates - typical of Ferula communis and Ferula arrigonii sardinian plants - show antiproliferative activity on human colon cancer less. The inhibitory doses 50%, calculated after 72 h of treatment, revealed that the antiproliferative capacity of the compounds was in the following descending order: ferutinin > 2alpha-OH-ferutidin > ferutidin > siol anisate > lapiferin > jaeskeanadiol. Evidence is presented that interaction with type II estrogen-binding sites (EBS) underlies this activity.

Multistep laryngeal carcinogenesis helps our understanding of the field cancerisation phenomenon: a review

In this paper, we try to briefly review the most recent knowledge on head and neck cancer, and especially multistep laryngeal carcinogenesis, and to simply explain how this has modified our understanding of field cancerisation phenomenon. Experimental studies, made possible by the recent evolution of microdissection systems, have demonstrated that the "spatial progression"of the histopathological phenotype in the surroundings of malignant or premalignant head and neck lesions correlates with molecular progression. Such a "spatial progression" can be hypothesised to reflect temporal progression. The field cancerisation process has been divided into three phases, each with its own histological and molecular characteristics. Each of these phases may have clinical implications: detection and monitoring of fields may help cancer prevention (molecular epidemiology), early detection of recurrence (or, more exactly, of second field tumours (SFTs)) (molecular diagnostics) and prognostic prediction after treatment. This model appears plausible, especially in explaining the development of multiple primary tumours (MPTs) in adjacent head and neck mucosal regions, with peculiar clinical and prognostic implications: These tumours can be defined as multiple field tumours (SFTs). However, the model, in our opinion, does not convincingly explain the development of second primary tumours (SPTs) at more distant sites, such as the lung, colon and prostate.

Kaempferol-induced growth inhibition and apoptosis in A549 lung cancer cells is mediated by activation of MEK-MAPK

A vast variety of naturally occurring substances have been shown to protect against experimental carcinogenesis and an increasing amount of evidence suggests that kaempferol may have cancer chemopreventative properties. However, the precise underlying protective mechanisms are poorly understood. To elucidate these mechanisms, we challenged human lung cancer cell line A549 with kaempferol and investigated its effects upon cellular growth and signal transduction pathways. Treatment of A549 cells with kaempferol resulted in a dose- and time-dependent reduction in cell viability and DNA synthesis with the rate of apoptosis equivalent to 0.9+/-0.5, 5.2+/-1.5, 16.8+/-2.0, 25.4+/-2.6, and 37.8+/-4.5% on treatment with 0, 17.5, 35.0, 52.5, and 70.0 microM kaempferol, respectively. Concomitantly, kaempferol treatments led to a 1.2-, 2.7-, 3.3-, and 3.4-fold increase in Bax. Similar elevations were also observed in Bad which increased 1.2-, 3.3-, 3.7-, and 4.7-fold, respectively, as compared to control. Bcl-2 and Bcl-xL expression were inhibited in a dose-dependent fashion. While the Akt-1 and phosphorylated Akt-1 were inhibited, the mitogen-activated protein kinase (MAPK) was activated upon kaempferol treatment. Kaempferol induced apoptosis was associated with the cleavage of caspase-7 and poly ADP-ribose polymerase (PARP). Inhibition of MEK1/2 but not PI-3 kinase blocked kaempferol-induced cleavage of caspase-7, PARP cleavage, and apoptosis. The results suggest that inactivation of Akt-1 and alteration of Bcl-2 family of proteins are not sufficient for kaempferol to induce apoptosis and activation of MEK-MAPK is a requirement for kaempferol-induced cell death machinery in A549 cells.

Flavonoid quercetin sensitizes a CD95-resistant cell line to apoptosis by activating protein kinase Calpha

We previously demonstrated that quercetin, a naturally occurring flavonoid with strong antioxidant properties, was able to enhance programmed cell death in HPB-acute lymphoblastic leukemia (ALL) cell line, derived from a human tymoma, when associated with the agonistic anti-CD95 monoclonal antibody. Here, we report that HPB-ALL cells are normally resistant to CD95-mediated apoptosis, and quercetin is able to sensitize this cell line through a mechanism independent of its antioxidant properties. In fact, other compounds structurally and functionally similar to quercetin, when associated with anti-CD95 antibody did not induce any CD95-mediated apoptosis, still maintaining their antioxidant capacity. We found that quercetin effects are mediated by the activation of PKCalpha. Treatment of HPB-ALL cells with quercetin slightly decreased PKCalpha activity, but when the flavonoid was associated with anti-CD95, the kinase activity increased by 12-fold with respect to the treatment with quercetin. In addition, overexpression of PKCalpha induced programmed cell death in the absence of any additional stimulus, while a kinase-defective mutant of PKCalpha was ineffective. Our data confirm the involvement of specific PKC isoforms in CD95 signaling and suggest, for the first time, that quercetin targets this pathway increasing apoptogenic response in a cell line resistant to CD95-mediated apoptosis.

Effects of tamoxifen on human squamous cell carcinoma lines of the head and neck

Tamoxifen (TAM) is a well-tolerated compound in the treatment of breast cancer and is primarily considered to act by competition with estrogen receptors (ER). Here we investigated the in vitro efficacy and potentially underlying mechanisms of TAM in established cell lines of squamous cell carcinomas of the head and neck (SCCHN). Using proliferation and apoptosis assays the antitumor activity of TAM in five SCCHN and the breast carcinoma line MCF-7 (positive control) was determined. MCF-7 was more sensitive to low-dose TAM (below 1 microM), whereas SCCHN showed significant growth inhibition at higher TAM concentrations (5-10 microM). Growth curve analysis and apoptosis assays were indicative for a cytostatic effect of low-dose TAM and high-dose TAM led to cell loss by apoptosis in sensitive SCCHN. In order to further characterize the observed antitumor effects we determined the amount of steroid hormone receptors with the dextran-coated charcoal method and immunocytochemistry. In addition, production of transforming growth factor (TGF-)-alpha, -beta1 and -beta2 was measured by ELISA, and protein kinase C (PKC) activity was assessed with a radioligand assay. Except MCF-7, none of the SCCHN lines was positive for ER. TAM caused decreased TGF-alpha and increased TGF-beta levels in MCF-7, but not in SCCHN supernatants. Furthermore, the antiestrogen reduced PKC activity in MCF-7, but not in SCCHN. In the present in vitro system, the observed antitumor activity of high-dose TAM in SCCHN cannot be explained by estrogen antagonism, alterations of TGF-alpha/beta levels or decreased PKC activity.

Increased cellular apoptosis after chronic aqueous exposure to nonylphenol and quercetin in adult medaka (Oryzias latipes)

Increasing evidence suggests that sublethal effects of natural or xenobiotic chemicals in the environment may be mediated via the stimulation of apoptosis. To investigate whether apoptosis can be induced in fish by weakly estrogenic and androgenic chemicals, adult male Japanese medaka (Oryzias latipes) were exposed to 100 ppb of the estrogenic alkylphenol, 4-nonylphenol, and adult female medaka were exposed to 100 ppb of the aromatase-inhibiting bioflavonoid, quercetin, for 6 weeks. Exposure to nonylphenol and quercetin had no significant effect on the length, weight or condition factors compared to solvent (acetone) controls in male or female medaka. Apoptosis was evaluated in blinded histological sections of whole medaka using terminal dideoxynucleotidyl transferase dUTP nick end labeling (TUNEL) that labels nuclei of cells containing apoptotic (fragmented) DNA. There was a six-fold greater extent of apoptosis in spermatocytes, Sertoli cells and Leydig-homologue cells, but not in spermatids of testes from nonylphenol-exposed male medaka compared to testes of solvent controls. No significant differences in the extent of apoptosis were detected in intestine, liver or kidney from the same male fish. Quercetin-treated female medaka had a significantly increased number of atretic ovarian follicles, but no significant differences in the extent of apoptosis in intestine, liver or kidney. These results suggest that nonylphenol caused testicular degeneration via increased testicular cell apoptosis, while quercetin may be ovotoxic via increased follicular atresia.

Prognostic significance of cyclooxygenase-2 in laryngeal squamous cell carcinoma

Epidermal growth factor receptor (EGFR) overexpression is an unfavorable prognostic marker in laryngeal squamous cell carcinoma (SCC). EGFR stimulates cyclooxygenase-2 (COX-2) expression in normal human keratinocytes and squamous carcinoma cells. Based on these observations a prognostic role of COX-2 expression in laryngeal SCC can be hypothesized. Consequently, COX-2 expression was studied in laryngeal SCC (median follow-up = 47 months; range: 2-87 months) by quantitative immunohistochemistry (n = 61) and EGFR by binding assay (n = 51). Well-differentiated regions of laryngeal SCC revealed strong COX-2 immunostaining, whereas histologically normal areas neighboring tumor as well as poorly-differentiated tumors were negative. Immunohistochemical results were confirmed by Western blot analyses. Cox's regression analysis showed that the combination of low levels of COX-2 integrated density and high levels of EGFR covariates provided strong prediction, at 5-year follow-up, of both poor overall survival (chi(2) = 12.905; p = 0.0016) and relapse-free survival (chi(2) = 9.209; p = 0.01). In vitro studies on CO-K3 cell line, obtained from an EGFR positive, COX-2 negative poorly-differentiated laryngeal SCC, revealed that EGF stimulation failed to induce COX-2 expression and PGE2 production suggesting a change in EGFR signaling pathway. These findings indicate that COX-2 is overexpressed in less aggressive, low grade laryngeal SCC, whereas its expression is lost when tumors progress to a more malignant phenotype.

Quercetin abrogates taxol-mediated signaling by inhibiting multiple kinases

Cell cycle block in G(2)/M initiates apoptosis, but the mechanism of this signaling cascade are largely unknown. The microtubule-perturbing agent Taxol has multiple effects on this signaling pathway and is a potent inducer of apoptosis. The specific pathways activated by low, clinically relevant concentrations of the drug are still largely unknown and are dependent on cell type and drug concentration. In this work, we have investigated why HeLa cells respond to Taxol by undergoing complete apoptosis, whereas MCF-7 cells remain in an intermediate phase with reduced death. Three phases were distinguished in these apoptotic pathways. The initial phase characterized by cellular detachment is followed by a second phase which includes the onset of apoptotic morphology, and p38 and Bcl-2 phosphorylation. These two phases are common to both cell lines. HeLa cells then proceed to the third and final execution phase, which culminates in death, whereas MCF-7 cells do not progress. Interestingly, the isoflavonoid Quercetin, a known general kinase inhibitor and an antioxidant, was able to prevent the onset of Taxol-induced cellular detachment and to protect from cell death. Moreover, it blocked Taxol-induced phosphorylation of p38 and Bcl-2, and prevented a Taxol-induced change in relative mobility of the apoptosis signal-regulating kinase 1 (Ask1). Our data elucidate the signaling pathways activated by Taxol at low clinically relevant concentrations.

Quercetin and tamoxifen sensitize human melanoma cells to hyperthermia

Hyperthermia produces regression of human cancer. Because hyperthermia has produced only limited results, attention has focused on searching for substances able to sensitize tumour cells to the effects of hyperthermia. The flavonoid quercetin has been reported to be a hyperthermic sensitizer in ovarian and uterine cervical tumours and in leukaemia. Quercetin and tamoxifen inhibit melanoma cell growth. We therefore investigated whether quercetin and tamoxifen can sensitize M10, M14 and MNT1 human melanoma cells to hyperthermia. We observed that both quercetin and tamoxifen synergize with hyperthermia (42.5 degrees C) in reducing the clonogenic activity of M14 and MNT1 and in inducing apoptotic cell death in all three cell lines. As revealed by flow cytometric and Northern blot analyses, quercetin and tamoxifen reduced heat shock protein-70 expression at both protein and mRNA levels. Our results suggest that quercetin and tamoxifen can be usefully combined with hyperthermia in the therapy of recurrent and/or metastatic melanoma.

Effects of structurally related flavonoids on cell cycle progression of human melanoma cells: regulation of cyclin-dependent kinases CDK2 and CDK1

We have investigated the effects of a series of flavonoids on cell proliferation and cell cycle distribution in human melanoma cells OCM-1. Among the compounds that potently inhibited OCM-1 cell proliferation, we show that the presence of a hydroxyl group at the 3'-position of the ring B in quercetin and luteolin, correlated to a G1 cell cycle arrest while its absence in kaempferol and apigenin correlated to a G2 block. Genistein with a hydroxyl at 5-position of the ring A arrested cells in G2 while daidzein which lacks it, induced an accumulation of cells in G1. We demonstrate that flavonoids, which induced a cell cycle block in G1, inhibited the activity of CDK2 by 40-60%. By contrast, those which caused an accumulation of cells in G2/M were without effect. On the other hand, while quercetin, daidzein and luteolin did not alter the activity of CDK1, kaempferol, apigenin and genistein inhibited this kinase by 50-70%. We demonstrate that the up-regulation of the CDK inhibitors p27(KIP1) and p21(CIP1) is likely responsible for the inhibition of CDK2 while inhibition of CDK1 was rather due to the phosphorylation of the kinase on Tyr15 residue.

Rutin inhibits ovariectomy-induced osteopenia in rats

Several studies suggest that polyphenols might exert a protective effect against osteopenia. The present experiment was conducted to observe the effects of rutin (quercetin-3-O-glucose rhamnose) on bone metabolism in ovariectomized (OVX) rats. Thirty 3-month-old Wistar rats were used. Twenty were OVX while the 10 controls were sham-operated (SH). Among the 20 OVX, for 90 days after surgery 10 were fed the same synthetic diet as the SH or OVX ones, but 0. 25% rutin (OVX + R) was added. At necropsy, the decrease in uterine weight was not different in OVX and OVX + R rats. Ovariectomy also induced a significant decrease in both total and distal metaphyseal femoral mineral density, which was prevented by rutin consumption. Moreover, femoral failure load, which was not different in OVX and SH rats, was even higher in OVX + R rats than in OVX or SH rats. In the same way, on day 90, both urinary deoxypyridinoline (DPD) excretion (a marker for bone resorption) and calciuria were higher in OVX rats than in OVX + R or SH rats. Simultaneously, plasma osteocalcin (OC) concentration (a marker for osteoblastic activity) was higher in OVX + R rats than in SH rats. High-performance liquid chromatography (HPLC) profiles of plasma samples from OVX + R rats revealed that mean plasma concentration of active metabolites (quercetin and isorhamnetin) from rutin was 9.46+/-1 microM, whereas it was undetectable in SH and OVX rats. These results indicate that rutin (and/or its metabolites), which appeared devoid of any uterotrophic activity, inhibits ovariectomy-induced trabecular bone loss in rats, both by slowing down resorption and increasing osteoblastic activity.

Chemoprevention studies of the flavonoids quercetin and rutin in normal and azoxymethane-treated mouse colon

In this study we investigated the chemopreventive effects of quercetin and rutin when added to standard AIN-76A diet and fed to normal and azoxymethane (AOM)-treated mice. Early changes in colonic mucosa were analyzed, including colonic cell proliferation, apoptotic cell death, cyclin D(1) expression and focal areas of dysplasia (FAD). The findings show that the number of colonic epithelial cells per crypt column increased (P: < 0.01) in each normal mouse group fed the flavonoids; AOM administration increased colonic crypt cell proliferation and resulted in a marked rise of bromodeoxyuridine-labeled cells in the lower proliferative zone of the crypt. Both supplementary dietary quercetin and rutin increased the apoptotic index and caused a redistribution of apoptotic cells along the crypt axis in normal mice fed a standard AIN-76A diet. The number of apoptotic cells/column and apoptotic indices markedly increased (P: < 0.01) in the AOM-treated group compared with untreated animals; apoptotic cells expanded throughout the colonic crypts after flavonoid supplementation and AOM administration. Positive cyclin D(1) expression was detected in mice on diets supplemented either with quercetin (P: < 0.01) or rutin (P: < 0.05). AOM administration resulted in the formation of FAD. Both the number of mice exhibiting FAD and the total numer of FAD observed were significantly reduced (P: < 0.01) in AOM-treated animals fed flavonoids compared with mice maintained on the standard AIN-76A diet. Surprisingly, however, quercetin alone was able to induce FAD in 22% of normal mice fed the standard AIN-76A diet.

Quercetin and anti-CD95(Fas/Apo1) enhance apoptosis in HPB-ALL cell line

Several malignant cell lines are resistant to CD95-(Apo1/Fas)-mediated apoptosis, even when the CD95 receptor is highly expressed. Sensitivity to CD95-induced apoptosis can be restored using different molecules. In this study, we showed that quercetin, a naturally occurring flavonoid, in association with the agonistic anti-CD95 monoclonal antibody, increases DNA fragmentation and caspase-3 activity in HPB-ALL cells. These cells have been selected for their known resistance to CD95-induced apoptosis. At molecular level, quercetin lowers the level of intracellular reactive oxygen species, reduces mitochondrial transmembrane potential, thereby leaving the expression of CD95 receptor unchanged.

Differential effect of estradiol on antibody secretion of murine hybridomas

The need for increased antibody production by hybridomas has been approached by the addition to cell cultures of different growth factors; in vitro addition of estradiol-17beta (E2) to human blood lymphocytes increases the accumulation of plasma-blasts and Ig-secreting cells. Four different murine-murine hybridomas secreting different monoclonal antibodies (MAbs) were treated with E2. Specific antibody concentration was measured by enzyme-linked immunoadsorbent assay (ELISA) in culture supernatants whereas expression of E2-receptor in the hybridoma cells was determined by polymerase chain reaction (PCR). When E2 was added as a growth supplement to alpha-estrogen receptor positive murine-murine hybridomas it enhanced MAb secretion by as much as 255%, in a dose-dependant manner. This effect lasted for as long as the alpha-estrogen receptor was detected in the hybridoma cells, was inhibited by tamoxifen and was not observed in alpha-estrogen receptor negative hybridomas. The synthetic estrogen analogue diethylstilbestrol had no effect. Estradiol-17beta should be added to the list of hybridoma-inducing growth factors.

Effects of quercetin and sunphenon on responses of cancer cells to heat shock damage

Quercetin is a flavonoid well known to inhibit growth and heat shock protein (HSP) synthesis of cancer cells. However, sunphenon has been scarcely reported concerning effects on cancer cells. We compared the effects of sunphenon with those of quercetin on the human cholangio-cellular carcinoma cell line (HuCC-T1). Both flavonoids inhibited HuCC-T1 growth in a concentration-dependent manner without reduction of HSP70 and HSP90 expression before heat shock damage. The heat shock reduced the cell viability of the quercetin-treated HuCC-T1, but not that of the sunphenon-treated cells. This inhibitory effect of quercetin on tolerance to heat shock is thought to be due to marked suppression of HSP72. Sunphenon conversely increased HSP72 expression after heat shock. Although neither flavonoid altered HSP90 protein levels before and after heat shock, quercetin delayed the reorganization of filamentous actin (F-actin) during the recovery period after heat shock. Since HSP90 could preserve F-actin structure during stresses, quercetin might affect the interaction between HSP90 and F-actin without influencing HSP90 expression. In conclusion, quercetin would be more useful than sunphenon in combined therapy with hyperthermia for cancer.