Synergistic antiproliferative activity of quercetin and cisplatin on ovarian cancer cell growth

It has been demonstrated that the flavonoid quercetin (3,3',4',5-7-pentahydroxyflavone) (Q) inhibits the growth of several cancer cell lines and that the antiproliferative activity of this substance is mediated by a so-called type II estrogen binding site (type II EBS). We investigated the effects of quercetin and cisplatin (CDDP) alone and in combination on the proliferation of the ovarian cancer cell line OVCA 433. Both drugs exhibited a dose-related growth inhibition in a range of concentrations between 0.01 and 2.5 microM and 0.01 and 2.5 micrograms/ml for Q and CDDP respectively. The combination of the two drugs resulted in a synergistic antiproliferative activity. Two other flavonoids tested, i.e., rutin (3-rhamnosylglucoside of quercetin) and hesperidin [7-b rutinoside of hesperetin (3'-5-3-hydroxy-4-methoxyflavone)] were ineffective both alone and in combination with CDDP. Since both rutin and hesperidin do not bind to type II EBS it can be hypothesized that Q synergizes with CDDP by acting through an interaction with these binding sites.     

Immunohistochemical and in situ hybridization detection of growth-hormone-producing cells in human thymoma.

We have studied 25 thymomas by both immunohistochemistry and in situ hybridization for the presence of growth hormone (GH)-producing cells. Our results indicate that 1) GH-immunoreactive cells were present in 13 of 17 thymomas of cortical and predominantly cortical type but not in medullary (spindled) thymomas (n = 3) or low- to high-grade thymic carcinomas (n = 5), 2) GH-positive cells were mainly located at the periphery of the neoplastic lobules, at the periphery of the perivascular spaces and in the areas of medullary differentiation, 3) cells containing GH mRNA appeared at locations similar to those of GH-immunoreactive cells, and 4) GH-immunoreactive material was present only in the epithelial cell component as revealed by immunoelectron microscopy. In conclusion, this paper demonstrates the occurrence of GH-producing cells in noncarcinoid thymic tumors. The relevance of GH in thymoma cell biology requires additional investigations.     

Glucocorticoid inhibitory action on the response to PHA of residual circulatory lymphocytes in renal transplant patients following immunosuppressive therapy

The inhibitory effect of glucocorticoids on the in vitro response to phytohaemagglutinin of the residual circulating T lymphocytes in renal transplant patients during maintenance immunosuppressive therapy with glucocorticosteroids and azathioprine has been investigated. As in normal subjects, the steroid-induced inhibition of transplanted patients' lymphocyte response was inversely correlated with the mitogen concentration used. On the other hand, the response of the various lymphocyte preparations from transplanted patients appeared less inhibited by steroids than the corresponding preparations from normal subjects. The addition to the culture of the adherent cell product interleukin 1 was effective in removing to a similar extent the steroid inhibitory effect on lymphocytes from normal and transplanted subjects. Thus, the lesser inhibitory effect of glucocorticoids on transplanted patient lymphocytes could be explained by the higher percentages of monocytes present in all peripheral blood mononuclear cell preparations. These results suggest that during immunosuppressive therapy with glucocorticoids and azathioprine the residual circulating lymphocytes have a responsiveness to in vitro dexamethasone suppression similar to that of normal peripheral blood lymphocytes.     

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 M. 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 M 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 anticancer drug either alone or in combination with ADR in multidrug-resistant breast tumor cells.This work was partially supported by grants from MURST (60% and 40%) and CNR (Special Projects: A.C.R.O. 94.01098.PF 39); R. DeVincenzo and G. Ferrandina are recipients of fellowships from the Italian Association for Cancer Research (AIRC); M. Cianfriglia was partly supported by the AIDS research project (contract 720/P)     

Quercetin inhibits the growth of a multidrug-resistant estrogen-receptor-negative MCF-7 human breast-cancer cell line expressing type II estrogen-binding sites

Summary It has been demonstrated that the flavonoid quercetin (3,3,4,5,7-pentahydroxyflavone; Q) inhibits the growth of several cancer cell lines. There is evidence suggesting that the antiproliferative activity of this substance is mediated by the so-called type II estrogen-binding, site (type II EBS). We looked for the presence of type II EBS and the effect of Q on the proliferation of an Adriamycinresistant estrogen-receptor-negative human breast-cancer cell line (MCF-7 ADRr). By whole-cell assay using estradiol labelled with 6,7-tritium ([³H]-E2) as a tracer, we demonstrated that MCF-7 ADRr cells contain type II EBSs. Competition analysis revealed that diethylstilbestrol (DES) and Q competed with similar potency for [³H]-Es binding to type II EBSs. The antiestrogen tamoxifen (TAM) competed for type II EBSs, albeit to a lesser extent than either DES or Q. Growth experiments demonstrated that Q and DES exerted a dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 m, whereas TAM was less effective. Q could also inhibit colony formation in a clonogenic assay. Our results indicate that multidrug-resistant estrogen-receptor-negative MCF-7 cells express, type II EBSs and are sensitive to the inhibitory effect of Q. This substance could be the parent compound of a novel class of anticancer agents.     

Homocysteine and nitrite levels are modulated by MTHFR 677C>T polymorphism in obese women treated with simvastatin

Higher homocysteine (Hcy) levels are associated with cardiovascular risk. The aim of the present study was to evaluate the effect of simvastatin treatment on circulating Hcy levels in obese women without hypertension, diabetes or dyslipidaemia; and to determine whether the 677C>T polymorphism located in methylenetetrahydrofolate reductase (NAD(P)H) (MTHFR) gene modulates the effects of this treatment on Hcy and nitrite (as a biomarker of nitric oxide (NO) bioavailability). Twenty‐five obese women (body mass index ≥ 30 kg/m²) who had received 20 mg/day simvastatin for 6 weeks were enrolled in the study. Venous blood samples were collected to measure plasma biomarkers and gene polymorphisms. Simvastatin treatment significantly reduced total cholesterol, low‐density lipoprotein–cholesterol, thiobarbituric acid‐reactive substances, high‐sensitivity C‐reactive protein and Hcy, whereas nitrite levels were increased. The reduction in Hcy levels in carriers of the T allele was ?20.3% compared with –9.4% in patients with the CC genotype. Importantly, before treatment, nitrite levels were significantly higher in patients with the CC genotype compared with T allele carriers, whereas after treatment these levels were similar between groups. Our findings demonstrate that obese women without comorbidities and carrying the T variant of the 677C>T polymorphism of MTHFR exhibit benefits with simvastatin treatment, mainly in terms of increased NO levels.     

Cyclo-oxygenase-2 (Cox-2) expression and resistance to platinum versus platinum/paclitaxel containing chemotherapy in advanced ovarian cancer

Background  

Cyclo-oxygenase-2 (COX-2), the key enzyme in the conversion of arachidonic acid to prostaglandins, is involved in critical steps of tumor onset and progression, and is a strong predictor of chemotherapy resistance and poor outcome in advanced ovarian cancer. To our knowledge, no data has been reported until now about the association between COX-2 status and response to different chemotherapy regimens.     

Regulation of cell cycle progression and apoptosis by beta-carotene in undifferentiated and differentiated HL-60 leukemia cells: possible involvement of a redox mechanism.

Although epidemiologic studies have demonstrated that a high intake of vegetables containing beta-carotene lowers the risk of cancer, recent intervention studies have revealed that beta-carotene supplementation to smokers resulted in a high incidence of lung cancer. We hypothesized that beta-carotene may act as a pro- or anticancerogenic agent by modulating pathways involved in cell growth and that such a modulation may involve a redox mechanism. To test this hypothesis, cell proliferation, apoptosis and redox status were evaluated in undifferentiated and dimethylsulfoxide-differentiated HL-60 cells exposed to beta-carotene. The carotenoid modified cell cycle progression and induced apoptosis in a dose-dependent manner. These effects were more remarkable in undifferentiated cells than in differentiated cells. In accord with these findings, in undifferentiated cells, beta-carotene was more effective in decreasing cyclin A and Bcl-2 expression and in increasing p21 and p27 expression. Neither Bcl-xL nor Bax expression were significantly modified by the carotenoid. From a mechanistic point of view, the delay in cell growth by beta-carotene was highly coincident with the increased intracellular reactive oxygen species production and oxidized glutathione content induced by the carotenoid. Moreover, alpha-tocopherol minimized the effects of beta-carotene on cell growth. These data provide evidence that beta-carotene modulates molecular pathways involved in cell cycle progression and apoptosis and support the hypothesis that a redox mechanism may be implicated. They also suggest that differentiated cells may be less susceptible to the carotenoid than highly neoplastic undifferentiated cells.     

Thymus changes in anti-MuSK-positive and -negative myasthenia gravis

Morphologic findings of thymuses from 32 anti-acetylcholine receptor (AChR)-negative myasthenia gravis patients, 12 with and 20 without antibodies against the muscle-specific kinase (MuSK), were compared with those from 30 AChR-positive subjects. In contrast with the high frequency of thymic hyperplastic changes in AChR-positive patients, in MuSK-positive subjects histologic alterations were minimal, arguing against an intrathymic disease pathogenesis. Since hyperplastic changes were seen in 35% of MuSK-negative patients, the thymus could be involved in some of these cases.