Inhibition of FLT3 expression by green tea catechins in FLT3 mutated-AML cells

Paclitaxel mediates the PI3K/AKT/mTOR pathway to reduce proliferation of FLT3‑ITD+ AML cells and promote apoptosis

Acute myeloid leukemia (AML) with internal tandem duplication (ITD) mutations in the FLT3 tyrosine kinase tend to have a poor prognosis. FLT3-ITD can promote the progress of AML by activating the PI3K/AKT/mTOR pathway. Paclitaxel (PTX) is a natural anticancer drug that has been widely used in chemotherapy for multiple malignancies. The present study used the CCK-8 assay, flow cytometry, PCR and western blotting to explore the anti-leukemia effect and possible mechanisms of PTX on MV4-11 cells with the FLT3-ITD mutation and the underlying mechanism. As a result, it was found that PTX could inhibit proliferation of MV4-11 cells and promoted apoptosis by inhibiting the PI3K/AKT/mTOR pathway.

Andrographis paniculata methanol extract suppresses the phosphorylation of ETV6‑NTRK3

ETS variant transcription factor 6 (ETV6)-neurotrophic receptor tyrosine kinase 3 (NTRK3) (EN) fusions are typically found in rare diseases, such as primary renal fibrosarcoma (only six cases have been reported), secretory carcinoma of the breast and salivary gland (1 case), and AML (4 cases). Few cases have been reported, and expression of the EN gene fusion requires additional clinical data and fundamental research to be supported. The aim of the present study was to determine the inhibitory effect of Andrographis paniculata methanol extract (MeAP) on EN-related cell lines, IMS-M2 and BaF3/EN, as well as evaluate the mechanism of action. Vero cells were used as control cells. Trypan blue staining and MTT were used to evaluate the inhibitory effect of MeAP on tested cells. Western blotting and immunoprecipitation were used to detect the activation of EN after MeAP treatment. The IC₅₀ values of MeAP were found to be 12.38±0.57 µg/ml (IMS-M2) and 13.06±0.49 µg/ml (BaF3/EN). MeAP was observed to inhibit cell proliferation in a time, dose, and cell density-dependent manner. The IC₅₀ value for MeAP in Vero cells was markedly higher, at 109.97±4.24 (µg/ml), indicating a much less sensitive effect. Furthermore, MeAP treatment inhibited EN phosphorylation and induced apoptosis in these cells. Collectively, the present study demonstrated that MeAP has an oncogenic effect on EN fusion-positive cell lines, in particular.

Integrative Hematology: State of the Art

Blood cancers are a group of diseases with thus far frequently poor prognosis. Although many new drugs, including target therapies, have been developed in recent years, there is still a need to expand our therapeutic armamentarium to better deal with these diseases. Integrative hematology was conceived as a discipline that enriches the patient's therapeutic possibilities with the use of supplements, vitamins and a nutritional approach aiming at improving the response to therapies and the clinical outcome. We will analyze the substances that have proved most useful in preclinical and clinical studies in some of the most frequent blood diseases or in those where these studies are more numerous; the importance of the nutritional approach and the role of the intestinal microbiota will also be emphasized.

Therapeutic Targeting of FLT3 in Acute Myeloid Leukemia: Current Status and Novel Approaches

FMS-like tyrosine kinase 3 (FLT3) is mutated in approximately 30% of acute myeloid leukemia (AML) patients. The presence of FLT3-ITD (internal tandem duplication, 20-25%) mutation and, to a lesser extent, FLT3-TKD (tyrosine kinase domain, 5-10%) mutation is associated with poorer diagnosis and therapy response since the leukemic cells become hyperproliferative and resistant to apoptosis after continuous activation of FLT3 signaling. Targeting FLT3 has been the focus of many pre-clinical and clinical studies. Hence, many small-molecule FLT3 inhibitors (FLT3is) have been developed, some of which are approved such as midostaurin and gilteritinib to be used in different clinical settings, either in combination with chemotherapy or alone. However, many questions regarding the best treatment strategy remain to be answered. On the other hand, various FLT3-dependent and -independent resistance mechanisms could be evolved during FLT3i therapy which limit their clinical impact. Therefore, identifying molecular mechanisms of resistance and developing novel strategies to overcome this obstacle is a current interest in the field. In this review, recent studies of approved FLT3i and knowledge about major resistance mechanisms of clinically approved FLT3i's will be discussed together with novel treatment approaches such as designing novel FLT3i and dual FLT3i and combination strategies including approved FLT3i plus small-molecule agents targeting altered molecules in the resistant cells to abrogate resistance. Moreover, how to choose an appropriate FLT3i for the patients will be summarized based on what is currently known from available clinical data. In addition, strategies beyond FLT3i's including immunotherapeutics, small-molecule FLT3 degraders, and flavonoids will be summarized to highlight potential alternatives in FLT3-mutated AML therapy.

Small Molecule Induced FLT3 Degradation

Target protein degrader is a new paradigm in the small molecule drug discovery field and relates to the term ‘event-driven pharmacology’. Fms-like tyrosine kinase 3 (FLT3) is a significant target for treating acute myeloid leukemia (AML). A few FLT3 kinase inhibitors are currently used in the clinic for AML patients. However, resistance to current FLT3 inhibitors has emerged, and strategies to overcome this resistance are required. Small molecules downregulating FLT3 protein level are reported, exhibiting antileukemic effects against AML cell lines. Small molecules with various mechanisms such as Hsp90 inhibition, proteasome inhibition, RET inhibition, and USP10 inhibition are explained. In addition, reports of FLT3 as a client of Hsp90, current knowledge of the ubiquitin proteasome system for FLT3 degradation, the relationship with FLT3 phosphorylation status and susceptibility of FLT3 degradation are discussed.

A natural acylphloroglucinol triggered antiproliferative possessions in HEL cells by impeding STAT3 signaling and attenuating angiogenesis in transgenic zebrafish model

Leukemia is responsible for a reason of death, globally. Even though there are several treatment regimens available in the clinics against this disease, a perfect chemotherapeutic agent for the same is still under investigation. Natural plant-derived secondary metabolites are used in clinics to treat leukemia for better benefits with reduced side-effects. Likely, several bioactive compounds from Callistemon sp. were reported for their bioactive benefits. Furthermore, acylphloroglucinol derivatives from Callistemon salignus, showed both antimicrobial and cytotoxic activities in various adherent human cancer cell lines. Thus, in the present study, a natural acylphloroglucinol (2,6-dihydroxy-4-methoxyisobutyrophenone, L72) was tested for its antiproliferative efficacy in HEL cells. The MTT and the cell cycle analysis study revealed that L72 treatment can offer antiproliferative effects, both time and dose-dependent manner, causing G₂/M cell cycle arrest. The western blot analysis revealed that L72 treatment triggered intrinsic apoptotic machinery and activated p21. Likewise, L72 could downregulate the gene expressions of XIAP, FLT3, IDH2, and SOD2, which was demonstrated by qPCR analysis, thus promoting its antiproliferative action. The L72 could impede STAT3 expression, which was evidenced by insilico autodock analysis and western blot analysis using STAT3 inhibitor, Pimozide. The treatment of transgenic (Flk-1+/egfr+) zebrafish embryos resulted in the STAT3 gene inhibition, proving its anti-angiogenic effect, as well. Thus, the study revealed that L72 could act as an antiproliferative agent, by triggering caspase-dependent intrinsic apoptosis, reducing cell proliferation by attenuating STAT3, and activating an anti-angiogenic pathway via Flk-1inhibition.

A comparative study of anti-leukemic effects of kaempferol and epigallocatechin-3-gallate (EGCG) on human leukemia HL-60 cells

OBJECTIVE

Acute promyelocytic leukemia (APL) is among the most threatening hematological malignant cancers. Defects in cell growth and apoptotic pathways lead to the pathogenesis of the disease as well as its resistance to therapy; therefore, it is a good model for examining pro-apoptotic agents. The present study compared the molecular mechanism induced by kaempferol and epigallocatechin gallate (EGCG) as well as all-trans retinoic acid (ATRA), in HL-60 leukemia cells during five days.

MATERIALS AND METHODS

Cell viability was determined by resazurin assay following treatment with ATRA (10 µM), EGCG, and kaempferol (12.5-100 µM), and apoptosis was detected by the ANX V/PI kit. Moreover, the levels of genes involved in apoptosis (PI3K, AKT, BCL2, BAX, P21, PTEN, CASP3, CASP8, and CASP9) and multi-drug resistance (MDR, ABCB1 and ABCC1) were assessed by using real-time PCR test.

RESULTS

Based on the findings, kaempferol decreased cell viability and increased apoptosis in HL60 cells more than EGCG. Apoptosis was induced via extrinsic and intrinsic pathways in HL60 cells by kaempferol and EGCG. In addition, kaempferol and EGCG increased apoptosis and inhibited MDR in a concentration- and time-dependent manner.

CONCLUSION

Kaempferol at high concentrations can be taken into consideration for treating patients with APL as compared with EGCG.

Sphagneticola Trilobata (L.) Pruski (Asteraceae) Methanol Extract Induces Apoptosis in Leukemia Cells through Suppression of BCR/ABL

We will study the effects of the methanol extract of Sphagneticola trilobata (L.) Pruski (Asteraceae) (MeST) on the growth of leukemia cells that may contain the BCR/ABL gene. This study also clarifies the mechanism of this effect on these cells. For this purpose, the cells harboring wild-type BCR/ABL, imatinib-resistant BCR/ABL (K562 and TCCYT315I), or Ba/F3 cells transfected with wild-type or mutant BCR/ABL genes were used. The results showed that MeST effectively inhibited the viability of leukemia cells in both a dose- and time-dependent manner. The effect of MeST seems to be more sensitive in the cells that carry imatinib-resistant BCR/ABL (especially the T315I BCR/ABL mutation) than those with wild-type BCR/ABL. Furthermore, we have demonstrated that the death caused by MeST is apoptosis and the treatment with MeST could suppress the expression of BCR/ABL, subsequently altering the downstream cascade of BCR/ABL such as AKT and MAPK signaling. In conclusion, MeST has been able to suppress the growth of leukemia cells harboring BCR/ABL. The mechanism of the anti-leukemic effect of MeST on cells harboring imatinib-resistant BCR/ABL mutations could be due to the disruption of the BCR/ABL oncoprotein signaling cascade.

(-)-Epigallocatechin-3-gallate induces apoptosis and differentiation in leukaemia by targeting reactive oxygen species and PIN1

(-)-Epigallocatechin-3-gallate (EGCG), the major active polyphenol extracted from green tea, has been shown to induce apoptosis and inhibit cell proliferation, cell invasion, angiogenesis and metastasis. Herein, we evaluated the in vivo effects of EGCG in acute myeloid leukaemia (AML) using an acute promyelocytic leukaemia (APL) experimental model (PML/RARα). Haematological analysis revealed that EGCG treatment reversed leucocytosis, anaemia and thrombocytopenia, and prolonged survival of PML/RARα mice. Notably, EGCG reduced leukaemia immature cells and promyelocytes in the bone marrow while increasing mature myeloid cells, possibly due to apoptosis increase and cell differentiation. The reduction of promyelocytes and neutrophils/monocytes increase detected in the peripheral blood, in addition to the increased percentage of bone marrow cells with aggregated promyelocytic leukaemia (PML) bodies staining and decreased expression of PML-RAR oncoprotein corroborates our results. In addition, EGCG increased expression of neutrophil differentiation markers such as CD11b, CD14, CD15 and CD66 in NB4 cells; and the combination of all-trans retinoic acid (ATRA) plus EGCG yield higher increase the expression of CD15 marker. These findings could be explained by a decrease of peptidyl-prolyl isomerase NIMA-interacting 1 (PIN1) expression and reactive oxygen species (ROS) increase. EGCG also decreased expression of substrate oncoproteins for PIN1 (including cyclin D1, NF-κB p65, c-MYC, and AKT) and 67 kDa laminin receptor (67LR) in the bone marrow cells. Moreover, EGCG showed inhibition of ROS production in NB4 cells in the presence of N-acetyl-L-cysteine (NAC), as well as a partial blockage of neutrophil differentiation and apoptosis, indicating that EGCG-activities involve/or are in response of oxidative stress. Furthermore, apoptosis of spleen cells was supported by increasing expression of BAD and BAX, parallel to BCL-2 and c-MYC decrease. The reduction of spleen weights of PML/RARα mice, as well as apoptosis induced by EGCG in NB4 cells in a dose-dependent manner confirms this assumption. Our results support further evaluation of EGCG in clinical trials for AML, since EGCG could represent a promising option for AML patient ineligible for current mainstay treatments.

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-β 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.

Investigation of Selected Flavonoid Derivatives as Potent FLT3 Inhibitors for the Potential Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive disease with a poor prognosis and a high degree of relapse seen in patients. Overexpression of FMS-like tyrosine kinase 3 (FLT3) is associated with up to 70% of AML patients. Wild-type FLT3 induces proliferation and inhibits apoptosis in AML cells, while uncontrolled proliferation of FLT3 kinase activity is also associated with FLT3 mutations. Therefore, inhibiting FLT3 activity is a promising AML therapy. Flavonoids are a group of phytochemicals that can target protein kinases, suggesting their potential antitumor activities. In this study, several plant-derived flavonoids have been identified with FLT3 inhibitory activity. Among these compounds, compound 40 (5,7,4'-trihydroxy-6-methoxyflavone) exhibited the most potent inhibition against not only FLT3 (IC₅₀ = 0.44 μM) but also FLT3-D835Y and FLT3-ITD mutants (IC₅₀ = 0.23 and 0.39 μM, respectively). The critical interactions between the FLT3 binding site and the compounds were identified by performing a structure-activity relationship analysis. Furthermore, the results of cellular assays revealed that compounds 28, 31, 32, and 40 exhibited significant cytotoxicity against two human AML cell lines (MOLM-13 and MV-4-11), and compounds 31, 32, and 40 resulted in cell apoptosis and G0/G1 cell cycle arrest. Collectively, these flavonoids have the potential to be further optimized as FLT3 inhibitors and provide valuable chemical information for the development of new AML drugs.

Combined effect of (-)-epigallocatechin-3-gallate and all-trans retinoic acid in FLT3-mutated cell lines

Patents diagnosed with acute promyelocytic leukemia were treated with Vesanoid^® [all-trans retinoic acid (ATRA)]. ATRA promotes the maturation and differentiation of leukemia cells and is therefore capable of reducing the symptoms of leukemia by preventing aggregation of myeloid cells. However, the clinical applications of ATRA are limited by its side effects, including acute retinoid resistance, hypertriglyceridemia, mucocutaneous dryness, nausea, brief recovery time relapse and drug resistance. Therefore, combinations of ATRA and other anticancer drugs are being investigated to overcome these limitations. In our previous study it was shown that in leukemia cells, (-)-epigallocatechin-3-gallate (EGCG) reduced cell proliferation and induced apoptotic cell death. In the present study, an in vitro evaluation of the effects of the combination of EGCG and ATRA on FLT3-mutated cell lines was performed using the isobologram method. The results showed that there was an additive effect in leukemic cells when treated with a combination of ATRA and EGCG. Thus, it was concluded that the cytotoxic effects of EGCG were improved by ATRA.

Preclinical Pharmacological Activities of Epigallocatechin-3-gallate in Signaling Pathways: An Update on Cancer

Epigallocatechin gallate (EGCG) is the main bioactive component of catechins predominantly present in svarious types of teas. EGCG is well known for a wide spectrum of biological activity as an anti-oxidative, anti-inflammatory, and anti-tumor agent. The effect of EGCG on cell death mechanisms via the induction of apoptosis, necrosis, and autophagy has been documented. Moreover, its anti-proliferative and chemopreventive action has been demonstrated in many cancer cell lines. It was also involved in the modulation of cyclooxygenase-2, in oxidative stress and inflammation of different cell processes. EGCG has been reported as a promising target for plasma membrane proteins, such as epidermal growth factor receptor (EGFR). In addition, it has been demonstrated a mechanism of action relying on the inhibition of ERK1/2, p38 MAPK, NF-κB, and vascular endothelial growth factor (VEGF). EGCG and its derivatives were used in proteasome inhibition and they were involved in epigenetic mechanisms. In summary, EGCG is the most predominant and bioactive constituent of teas and it has a pivotal role in cancer prevention. Its preclinical pharmacological activities are associated with complex molecular mechanisms that involve numerous signaling pathways.

Investigation of Hot Spot Region in XIAP Inhibitor Binding Site by Fragment Molecular Orbital Method

X-linked inhibitor of apoptosis protein (XIAP) is an important regulator of cancer cell survival whose BIR3 domain (XIAP-BIR3) recognizes the Smac N-terminal tetrapeptide sequence (AVPI), making it an attractive protein-protein interaction (PPI) target for cancer therapies. We used the fragment molecular orbital (FMO) method to study the binding modes and affinities between XIAP-BIR3 and a series of its inhibitors (1-8) that mimic the AVPI binding motif; the inhibitors had common interactions with key residues in a hot spot region of XIAP-BIR3 (P1-P4 subpockets) with increased binding affinity mainly attributed to specific interactions with the P1 and P4 subpockets. Based on the structural information from FMO results, we proposed a novel XIAP natural product inhibitor, neoeriocitrin 10, which was derived from our preciously reported XIAP-BIR3 inhibitor 9, can be used as a highly potent candidate for XIAP-BIR3 inhibition. We also performed pair interaction energy decomposition analysis to investigate the binding energies between specific binding residues and individual ligands, showing that the novel natural product neoeriocitrin 10 had a higher binding affinity than epicatechin gallate 9. Molecular docking and dynamics simulations were performed to explore the mode of binding between 10 and XIAP-BIR3, demonstrating that 10 binds more strongly to the P1 and P4 pockets than 9. Overall, we present a novel natural product, neoeriocitrin 10, and demonstrate that the FMO method can be used to identify hot spots in PPIs and design new compounds for XIAP inhibition.

ETV6/FLT3 Fusion Is a Novel Client Protein of Hsp90

FMS-like tyrosine kinase-3 fragments from exon 14 to the end without any mutations or deletions have been reported to fuse to ETV6 (TEL) in a few cases of myeloid/lymphoid neoplasms with eosinophilia carrying a translocation t(12;13)(p13;q12). This fusion protein confers constitutive activation on the FLT3 fragment and induces factor-independent growth in transfected Ba/F3 cells, indicating that it is an oncoprotein. However, the mechanism controlling the stability of this oncoprotein is unknown. In this study, we focus on finding factors controlling the stability of ETV6/FLT3. We have shown that the stability of ETV6/FLT3 is regulated by the Hsp90 chaperone. ETV6/FLT3 fusion protein forms a complex with Hsp90 by coimmunoprecipitation analyses using an Hsp90 antibody. The association between ETV6/FLT3 fusion protein and Hsp90 was impaired after treating ETV6/FLT3 transient transfection cos7 cells with 17-allylamino-17-demethoxygeldanamycin (17-AAG). 17-AAG induced a time- and dose-dependent downregulation of ectopically expressed ETV6/FLT3 protein in cos7 and HeLa-transfected cells. By using cycloheximide to block new protein translation, we found that 17-AAG accelerated the decay of ETV6/FLT3. Our findings could contribute to more understanding of the ETV6/FLT3 regulation through Hsp90 chaperone and open the way to finding effective treatment strategies for this rare disease.

Epigallocatechin-3-gallate enhances differentiation of acute promyelocytic leukemia cells via inhibition of PML-RARα and HDAC1

The use of all-trans retinoic acid (ATRA) has dramatically improved the treatment and survival rate of patients with acute promyelocytic leukemia (APL). However, toxicity and resistance to this drug are major problems in the treatment of APL with ATRA. Earlier studies have suggested that the green tea polyphenol epigallocatechin gallate (EGCG) induces cell death in hematopoietic neoplasms without adversely affecting normal cells. In the present study, the potential therapeutic effect of EGCG in APL and the underlying molecular mechanisms were investigated. EGCG (100 μM) significantly inhibited proliferation and induced apoptosis in HL-60 and NB4 cells. This effect was associated with decreased expressions of multidrug resistance proteins ABCB1, and ABCC1, whereas the expressions of pro-apoptotic genes CASP3, CASP8, p21, and Bax/Bcl-2 ratio were significantly increased. EGCG, at 25 μM concentration, induced differentiation of leukemic cells towards granulocytic pattern in a similar manner to that observed for ATRA (1 μM). Furthermore, EGCG suppressed the expression of clinical marker PML/RARα in NB4 cells and reduced the expression of HDAC1 in leukemic cells. In conclusion, the results suggested that EGCG can be considered as a potential treatment for APL.

Natural products used as a chemical library for protein-protein interaction targeted drug discovery

Protein-protein interactions (PPIs), which are essential for cellular processes, have been recognized as attractive therapeutic targets. Therefore, the construction of a PPI-focused chemical library is an inevitable necessity for future drug discovery. Natural products have been used as traditional medicines to treat human diseases for millennia; in addition, their molecular scaffolds have been used in diverse approved drugs and drug candidates. The recent discovery of the ability of natural products to inhibit PPIs led us to use natural products as a chemical library for PPI-targeted drug discovery. In this study, we collected natural products (NPDB) from non-commercial and in-house databases to analyze their similarities to small-molecule PPI inhibitors (iPPIs) and FDA-approved drugs by using eight molecular descriptors. Then, we evaluated the distribution of NPDB and iPPIs in the chemical space, represented by the molecular fingerprint and molecular scaffolds, to identify the promising scaffolds, which could interfere with PPIs. To investigate the ability of natural products to inhibit PPI targets, molecular docking was used. Then, we predicted a set of high-potency natural products by using the iPPI-likeness score based on a docking score-weighted model. These selected natural products showed high binding affinities to the PPI target, namely XIAP, which were validated in an in vitro experiment. In addition, the natural products with novel scaffolds might provide a promising starting point for further medicinal chemistry developments. Overall, our study shows the potency of natural products in targeting PPIs, which might help in the design of a PPI-focused chemical library for future drug discovery.

Established Human Cell Lines as Models to Study Anti-leukemic Effects of Flavonoids

Despite the extensive work on pathological mechanisms and some recent advances in the treatment of different hematological malignancies, leukemia continues to present a significant challenge being frequently considered as incurable disease. Therefore, the development of novel therapeutic agents with high efficacy and low toxicity is urgently needed to improve the overall survival rate of patients. In this comprehensive review article, the current knowledge about the anticancer activities of flavonoids as plant secondary polyphenolic metabolites in the most commonly used human established leukemia cell lines (HL-60, NB4, KG1a, U937, THP-1, K562, Jurkat, CCRF- CEM, MOLT-3, and MOLT-4) is compiled, revealing clear anti-proliferative, pro-apoptotic, cell cycle arresting, and differentiation inducing effects for certain compounds. Considering the low toxicity of these substances in normal blood cells, the presented data show a great potential of flavonoids to be developed into novel anti-leukemia agents applicable also in the malignant cells resistant to the current conventional chemotherapeutic drugs.

Epigallocatechin Gallate Nanodelivery Systems for Cancer Therapy

Cancer is one of the leading causes of morbidity and mortality all over the world. Conventional treatments, such as chemotherapy, are generally expensive, highly toxic and lack efficiency. Cancer chemoprevention using phytochemicals is emerging as a promising approach for the treatment of early carcinogenic processes. (−)-Epigallocatechin-3-gallate (EGCG) is the major bioactive constituent in green tea with numerous health benefits including anti-cancer activity, which has been intensively studied. Besides its potential for chemoprevention, EGCG has also been shown to synergize with common anti-cancer agents, which makes it a suitable adjuvant in chemotherapy. However, limitations in terms of stability and bioavailability have hampered its application in clinical settings. Nanotechnology may have an important role in improving the pharmacokinetic and pharmacodynamics of EGCG. Indeed, several studies have already reported the use of nanoparticles as delivery vehicles of EGCG for cancer therapy. The aim of this article is to discuss the EGCG molecule and its associated health benefits, particularly its anti-cancer activity and provide an overview of the studies that have employed nanotechnology strategies to enhance EGCG’s properties and potentiate its anti-tumoral activity.

Green tea consumption and glutathione S-transferases genetic polymorphisms on the risk of adult leukemia

PURPOSE

Green tea may have a beneficial role of inhibiting leukemia. Glutathione S-transferases (GSTs) are known to detoxify certain carcinogens. We investigated the roles of green tea consumption and polymorphisms of GSTM1, GSTT1 and GSTP1 on the risk of adult leukemia, and to determine whether the associations varied within GSTs genotypes.

METHODS

A multicenter case-control study was conducted in China, 2008-2013. It comprised 442 incident, hematologically confirmed adult leukemia cases and 442 outpatient controls, individually matched to cases by gender, birth quinquennium and study site. Data were collected by face-to-face interview using a validated questionnaire. Genetic polymorphisms were assayed by PCR.

RESULTS

An inverse association between green tea consumption and adult leukemia risk was observed. Compared with non-tea drinkers, the adjusted odds ratios (95 % confidence intervals) were 0.50 (0.27-0.93), 0.31 (0.17-0.55) and 0.53 (0.29-0.99) for those who, respectively, consumed green tea >20 years, ≥2 cups daily and dried tea leaves >1000 g annually. In assessing the associations by GSTs genotypes, risk reduction associated with green tea consumption was stronger in individuals with the GSTT1-null genotype (OR 0.24; 95 % CI 0.11-0.53) than GSTT1-normal carriers (OR 0.67; 95 % CI 0.42-1.05; P interaction = 0.02). GSTM1 and GSTP1 did not significantly modify the inverse association of leukemia with green tea.

CONCLUSIONS

The results suggest that regular daily green tea consumption may reduce leukemia risk in Chinese adults regardless of GSTM1 and GSTP1 polymorphic status. The association between green tea and adult leukemia risk varied with GSTT1 genotype and highlights further study.

Synergistic effect of all‑trans retinoic acid in combination with protein kinase C 412 in FMS-like tyrosine kinase 3-mutated acute myeloid leukemia cells

Acute myeloid leukemia (AML) is a heterogeneous disease. Numerous molecular abnormalities have been identified in AML and, amongst these, FMS‑like tyrosine kinase 3 (FLT3) mutations are one of the most common somatic alterations detected. In the present study, an in vitro investigation was performed to evaluate the effects of all‑trans retinoic acid (ATRA) and PKC412, alone and in combination, in FLT3‑mutated AML cell lines. Trypan blue exclusion test, as well as morphological, western blot and isobologram analyses were conducted. The results indicated that the combined ATRA and PKC412 treatment exhibited additive or synergistic effects in FLT3‑mutated AML cell lines. These results provided in vitro evidence for the future clinical trials evaluating the effects of a combination treatment using PKC412 and ATRA on AML patients with FLT3‑mutations.

Down-regulated expression of NPM1 in IMS-M2 cell line by (-)-epigallocatechin-3-gallate

OBJECTIVE

To investigate the inhibited effect of epigallocatechin-3-gallate (EGCG) on the expression of NPM1 in IMS-M2 cells harboring the NPM1 mutations.

METHODS

Cell proliferation assay was performed to test the effects of EGCG on cell growth of IMS-M2 cells harboring the NPM1 mutations. Western blot analysis were performed to test the protein expression of NPM1, AKT, those associated with apoptosis.

RESULTS

EGCG can down-regulate the expression of NPM1 in IMS-M2 cells harboring the NPM1 mutations. Moreover, EGCG also suppressed the cell proliferation and induced apoptosis in IMS-M2 cells.

CONCLUSIONS

The results suggested that EGCG could be considered as a reagent for treatment of AML patients with NPM1 mutations.

Inhibitory effect of turmeric curcuminoids on FLT3 expression and cell cycle arrest in the FLT3-overexpressing EoL-1 leukemic cell line

Leukemia is a hematologic malignancy with a frequent incidence and high mortality rate. Previous studies have shown that the FLT3 gene is overexpressed in leukemic blast cells, especially in acute myeloid leukemia. In this study, a commercially available curcuminoid mixture (1), pure curcumin (2), pure demethoxycurcumin (3), and pure bisdemethoxycurcumin (4) were investigated for their inhibitory effects on cell growth, FLT3 expression, and cell cycle progression in an FLT3-overexpressing EoL-1 leukemic cell line using an MTT assay, Western blotting, and flow cytometry, respectively. The mixture (1) and compounds 2-4 demonstrated cytotoxic effects with IC50 values ranging from 6.5 to 22.5 μM. A significant decrease in FLT3 protein levels was found after curcuminoid treatment with IC20 doses, especially with mixture 1 and compound 2. In addition, mixture 1 and curcumin (2) showed activity on cell cycle arrest at the G0/G1 phase and decreased the FLT3 and STAT5A protein levels in a dose-dependent manner. Compound 2 demonstrated the greatest potential for inhibiting cell growth, cell cycle progression, and FLT3 expression in EoL-1 cells. This investigation has provided new findings regarding the effect of turmeric curcuminoids on FLT3 expression in leukemic cells.