Immunomodulatory Effect of Green Tea Treatment in Combination with Low-dose Chemotherapy in Elderly Acute Myeloid Leukemia Patients with Myelodysplasia-related Changes.

Green tea (GT) treatment was evaluated for its effect on the immune and antineoplastic response of elderly acute myeloid leukemia patients with myelodysplasia-related changes (AML-MRC) who are ineligible for aggressive chemotherapy and bone marrow transplants. The eligible patients enrolled in the study (n = 10) received oral doses of GT extract (1000 mg/day) alone or combined with low-dose cytarabine chemotherapy for at least 6 months and/or until progression. Bone marrow (BM) and peripheral blood (PB) were evaluated monthly. Median survival was increased as compared to the control cohort, though not statistically different. Interestingly, improvements in the immunological profile of patients were found. After 30 days, an activated and cytotoxic phenotype was detected: GT increased total and naïve/effector CD8+ T cells, perforin+/granzyme B+ natural killer cells, monocytes, and classical monocytes with increased reactive oxygen species (ROS) production. A reduction in the immunosuppressive profile was also observed: GT reduced TGF-ß and IL-4 expression, and decreased regulatory T cell and CXCR4+ regulatory T cell frequencies. ROS levels and CXCR4 expression were reduced in bone marrow CD34+ cells, as well as nuclear factor erythroid 2-related factor 2 (NRF2) and hypoxia-inducible factor 1α (HIF-1α) expression in biopsies. Immune modulation induced by GT appears to occur, regardless of tumor burden, as soon as 30 days after intake and is maintained for up to 180 days, even in the presence of low-dose chemotherapy. This pilot study highlights that GT extracts are safe and could improve the immune system of elderly AML-MRC patients.

The polyphenol quercetin induces cell death in leukemia by targeting epigenetic regulators of pro-apoptotic genes.

BACKGROUND: In the present study, we investigated the molecular mechanisms underlying the pro-apoptotic effects of quercetin (Qu) by evaluating the effect of Qu treatment on DNA methylation and posttranslational histone modifications of genes related to the apoptosis pathway. This study was performed in vivo in two human xenograft acute myeloid leukemia (AML) models and in vitro using HL60 and U937 cell lines. RESULTS: Qu treatment almost eliminates DNMT1 and DNMT3a expression, and this regulation was in part STAT-3 dependent. The treatment also downregulated class I HDACs. Furthermore, treatment of the cell lines with the proteasome inhibitor, MG132, together with Qu prevented degradation of class I HDACs compared to cells treated with Qu alone, indicating increased proteasome degradation of class I HDACS by Qu. Qu induced demethylation of the pro-apoptotic BCL2L11, DAPK1 genes, in a dose- and time-dependent manner. Moreover, Qu (50 µmol/L) treatment of cell lines for 48 h caused accumulation of acetylated histone 3 and histone 4, resulting in three- to ten fold increases in the promoter region of DAPK1, BCL2L11, BAX, APAF1, BNIP3, and BNIP3L. In addition, Qu treatment significantly increased the mRNA levels of all these genes, when compared to cells treated with vehicle only (control cells) (*p < 0.05). CONCLUSIONS: In summary, our results showed that enhanced apoptosis, induced by Qu, might be caused in part by its DNA demethylating activity, by HDAC inhibition, and by the enrichment of H3ac and H4ac in the promoter regions of genes involved in the apoptosis pathway, leading to their transcription activation.

Antitumor activities of Quercetin and Green Tea in xenografts of human leukemia HL60 cells.

Quercetin is one of the most abundant flavonoids, present in fruits and vegetables and has been shown to have multiple properties capable of reducing cell growth in cancer cells. Green tea is a widely consumed beverage, known for a potential source of free radical scavenging and anti-cancer activities. Herein, we investigate the in vivo antitumor efficacy of quercetin and green tea in human leukemia. Human tumors were xenografted into NOD/SCID mice. Quercetin and green tea reduced tumor growth in HL-60 xenografts accompanied by decreased expression of anti-apoptotic proteins, BCL-2, BCL-XL and MCL-1 and increased expression of BAX, a pro-apoptotic protein. Moreover, caspase-3 was activated to a greater extent after quercetin and green tea treatment. Quercetin and green tea also mediated G1 phase cell cycle arrest in HL-60 xenografts. Treatment with quercetin and green tea induced conversion of LC3-I to LC3-II as well as activation of autophagy proteins, suggesting that quercetin and green tea initiate the autophagic progression. We have provided evidence that quercetin and green tea induces signaling at the level of apoptosis, cell cycle and autophagy which converge to antigrowth effects in HL-60 xenograft mice suggesting that these compounds may be a compelling ally in cancer treatment.

Multitarget effects of quercetin in leukemia.

This study proposes to investigate quercetin antitumor efficacy in vitro and in vivo, using the P39 cell line as a model. The experimental design comprised leukemic cells or xenografts of P39 cells, treated in vitro or in vivo, respectively, with quercetin; apoptosis, cell-cycle and autophagy activation were then evaluated. Quercetin caused pronounced apoptosis in P39 leukemia cells, followed by Bcl-2, Bcl-xL, Mcl-1 downregulation, Bax upregulation, and mitochondrial translocation, triggering cytochrome c release and caspases activation. Quercetin also induced the expression of FasL protein. Furthermore, our results demonstrated an antioxidant activity of quercetin. Quercetin treatment resulted in an increased cell arrest in G1 phase of the cell cycle, with pronounced decrease in CDK2, CDK6, cyclin D, cyclin E, and cyclin A proteins, decreased Rb phosphorylation and increased p21 and p27 expression. Quercetin induced autophagosome formation in the P39 cell line. Autophagy inhibition induced by quercetin with chloroquine triggered apoptosis but did not alter quercetin modulation in the G1 phase. P39 cell treatment with a combination of quercetin and selective inhibitors of ERK1/2 and/or JNK (PD184352 or SP600125, respectively), significantly decreased cells in G1 phase, this treatment, however, did not change the apoptotic cell number. Furthermore, in vivo administration of quercetin significantly reduced tumor volume in P39 xenografts and confirmed in vitro results regarding apoptosis, autophagy, and cell-cycle arrest. The antitumor activity of quercetin both in vitro and in vivo revealed in this study, point to quercetin as an attractive antitumor agent for hematologic malignancies.

Differential effects of nitrostyrene derivatives on myelopoiesis involve regulation of C/EBPα and p38MAPK activity.

Bone marrow failure syndromes and MDS represent a heterogenous group of diseases, characterized by ineffective myelopoiesis, the risk of clonal evolution and a generally poor response to chemotherapy-based treatment regimen. Nitrostyrene derivatives have been studied as protein phosphatase inhibitors in various tumor models. Pharmacological studies have identified nitrostyrene as the structural core underlying a pro-apoptotic effect in tumor cells, yet their effects on normal cells, including those of the hematopoietic system, are largely unknown. In this study, utilizing umbilical cord blood-derived myeloid progenitor cells, patient-derived bone marrow cells, and a (BALB/c) mouse model; we investigated the effects of treatment with two nitrostyrene derivatives (NTS1 and NTS2) on myeloid development. We demonstrate that these compounds stimulate the expansion and differentiation of myeloid progenitors in vitro and improve myeloid reconstitution after chemotherapy-induced bone marrow depletion in vitro and in vivo. These effects were accompanied by increased C/EBPα expression and activity and inhibition of the p38MAPK signalling pathway. Together, our data suggest that nitrostyrenes improve myelopoiesis and represent potential new treatment strategies for patients suffering from bone marrow failure syndromes, hypocellular myelodysplastic syndrome and chemotherapy-induced aplasia.

Koninginins, phospholipase A2 inhibitors from endophytic fungus Trichoderma koningii.

Many isolated compounds from endophytic fungus have been useful to human beings, mainly those with medicinal applications and particularly those that can be used in inflammatory processes. Trichoderma fungi produce substances known as koninginins that have great structural similarity to compounds like flavonoids and vitamin E, which are able to inhibit the phospholipase A(2) (PLA(2)). In this work, koninginins A, E and F (KonA, KonE and KonF, respectivamente) isolated from Trichoderma koningii had their capabilities of inhibiting edema-inducing, myotoxic and enzymatic activities of the total venom of Bothrops jararacussu (jararacuçu) snake analyzed, as well as one of its homolog forms of phospholipases A(2) (bjPLA(2)-group IIB) and human secreted PLA(2) protein fusion (hsPLA(2)-group IIA). KonA was not efficient in inhibiting the three activities analyzed in all the tests performed. Nevertheless, KonE and KonF present great capability in inhibiting the effects provoked not only by the venom but also by both PLA(2). The activities inhibition shown by KonE and KonF over the enzymes is significantly higher than those obtained over the total venom. KonE and KonF were slightly more efficient in the inhibition of the group IIB (bjPLA(2)) PLA(2) effects than in the inhibition of the group IIA (hsPLA(2)) PLA(2) effects. KonE and KonF structures are similar to vitamin E and, possibly, the action mode of these molecules is similar to the one produced by the vitamin. These results, apparently, indicate that koninginins E and F, as well as vitamin E, present structural regions that might be used as start points in seeking for new and specific anti-inflammatory drugs against such enzymes.