Pure total flavonoids from Citrus paradisi Macfadyen act synergistically with arsenic trioxide in inducing apoptosis of Kasumi-1 leukemia cells in vitro

Combination of HDE and BIIB021 efficiently inhibits cell proliferation and induces apoptosis via downregulating hTERT in myelodysplastic syndromes

Treatment for higher-risk patients with myelodysplastic syndrome (MDS) should aim to modify the disease course by avoiding progression to acute myeloid leukemia and improving survival. When a patient is not eligible for intensive chemotherapy and lacks a donor hematopoietic cell source, or for a patient in a poor economic situation, consideration can be given to the use of Chinese herbal medicine. Numerous plant extracts, such as camptothecin, vinblastine and paclitaxel, have been reported to display antitumor effects, serving as potential therapeutic strategies for cancer. In the present study, the ultra-performance liquid chromatography-tandem mass spectrometry system (Waters Corporation) was used to detect the main chemical components of HDE, CCK-8 assay to detect the effects of HDE and BIIB021 on the proliferation of SKM-1 cells; and designed hTERT-small interfering (si)RNAs to detect the effects of HDE and BIIB021 on SKM-1 cell apoptosis after HTERT gene knockdown. The present study investigated a newly extracted coumarin HDE, the active component in Oldenlandia diffusa Willd, which efficiently inhibited SKM-1 (MDS cell line) proliferation and induced apoptosis, as determined by performing Cell Counting Kit-8 and flow cytometry assays, respectively. The effect of HDE was associated with decreased telomerase activity. Moreover, heat shock protein 90 inhibitor BIIB021 significantly enhanced the antitumor effects of HDE on SKM-1 cells. In addition, SKM-1 cell apoptosis was increased in human telomerase reverse transcriptase (hTERT)-knockdown cells compared with the negative control group. Cell apoptosis in hTERT-knockdown SKM-1 cells was further enhanced following HDE, BIIB021 or combination treatment, as evidenced by increased levels of cleaved caspase 3, cleaved caspase 8 and cleaved poly ADP ribose polymerase. Collectively, the results indicated synergistic antitumor effects of HDE and BIIB021, providing a novel therapeutic combination for higher-risk MDS.

Citrus Peel Flavonoids as Potential Cancer Prevention Agents

Citrus fruit and in particular flavonoid compounds from citrus peel have been identified as agents with utility in the treatment of cancer. This review provides a background and overview regarding the compounds found within citrus peel with putative anticancer potential as well as the associated in vitro and in vivo studies. Historical studies have identified a number of cellular processes that can be modulated by citrus peel flavonoids including cell proliferation, cell cycle regulation, apoptosis, metastasis, and angiogenesis. More recently, molecular studies have started to elucidate the underlying cell signaling pathways that are responsible for the flavonoids' mechanism of action. These growing data support further research into the chemopreventative potential of citrus peel extracts, and purified flavonoids in particular. This critical review highlights new research in the field and synthesizes the pathways modulated by flavonoids and other polyphenolic compounds into a generalized schema.

Leukemia therapy by flavonoids: Future and involved mechanisms

Flavonoids are a varied family of phytonutrients (plant chemicals) usually are detected in fruits and vegetables. In this big family, there exist more than 10,000 members that is separated into six chief subtypes: isoflavonols, flavonoenes, flavones, flavonols, anthocyanins, and chalcones. The natural compounds, such as fruits, have visible positive effects in regulating of survival involved signaling pathways that performance as the regulator of cell survival, growth, and proliferation. Researchers have established that commonly consumption up flavonoids decreases incidence and development risk of certain cancers, especially leukemia. Flavonoids have been able to induce apoptosis and stimulate cell cycle arrest in cancer cells via different pathways. Similarly, they have antiangiogenesis and antimetastasis capability, which were shown in wide ranges of cancer cells, particularly, leukemia. It seems that flavonoid because of their widespread approval, evident safety and low rate of side effects, have hopeful anticarcinogenic potential for leukemia therapy. Based on the last decade reports, the most important acting mechanisms of these natural compounds in leukemia cells are stimulating of apoptosis pathways by upregulation of caspase 3, 8, 9 and poly ADP-ribose polymerase (PARP) and proapoptotic proteins, particularly Bax activation. As well, they can induce cell cycle arrest in target cells not only via increasing of activated levels of p21 and p53 but also by inhibition of cyclins and cyclin-dependent kinases. Furthermore, attenuation of neclear factor-κB and signal transducer and activator of transcription 3 activation, suppression of signaling pathway and downregulation of intracellular antiapoptotic proteins are other significant antileukemic function mechanism of flavonoids. Overall, it appears that flavonoids are promising and effective compounds in the field of leukemia therapy. In this review, we tried to accumulate and revise most promising flavonoids and finally declared their major working mechanisms in leukemia cells.

Inhibition of X-linked inhibitor of apoptosis protein enhances anti-tumor potency of pure total flavonoids on the growth of leukemic cells

Flavonoids, a vast group of polyphenols widely distributed in plants, are known to possess a range of biological activities and potential anti-tumor effects. X-linked inhibitor of apoptosis protein (XIAP) promotes the progression of leukemia by preventing tumor cells undergoing apoptosis. The present study investigated the potential effects and underlying mechanisms of pure total flavonoids from Citrus paradisi Macfad (PTFC) on human U937 cells, and explored the effects of short hairpin (sh)RNA-mediated XIAP knockdown on the anti-cancer effects of PTFC. Western blotting was used to determine level of apoptosis-associated effectors following PTFC treatment. A lentiviral vector of RNA interference of XIAP gene was constructed to downregulate XIAP expression. MTT assay and flow cytometry were used to determine the effects of PTFC separately or combined with XIAP-shRNA on inhibition and apoptosis of U937 cells, respectively. Treatment with PTFC effectively inhibited leukemic cell proliferation in a dose- and time-dependent manner. PTFC induced apoptosis of U937 cells in a dose-dependent manner, at a particular concentration range, by decreasing XIAP expression levels and activating caspases-3, −7 and −9. PTFC treatment combined with XIAP-shRNA additionally demonstrated a marked increase in cell apoptosis, compared with PTFC or XIAP-shRNA alone (P<0.05). Therefore, these findings suggest that PTFC inhibits growth and induces apoptosis in U937 cells in vitro. Furthermore, suppression of XIAP expression enhances these effects.

Antimelanogenic effects of Inula britannica flower petal extract fermented by Lactobacillus plantarum KCCM 11613P*

The inhibitory effects of Lactobacillus plantarum-fermented and non-fermented Inula britannica extracts on the tyrosinase activity were comparatively investigated to examine whether and how they improve the whitening activity, and the contents of total flavonoids and polyphenolics as bioactive compounds were determined. The skin whitening activity using in vitro or ex vivo tyrosinase and L-3,4-dihydroxyphenylalanine (L-DOPA) staining was examined. The total flavonoid content (TFC) was increased by 13.4% after 72 h-fermentation. The viabilities of the B16F10 cells treated with the fermented and non-fermented control extracts were 100.26% and 92.15% at 500 µg/ml, respectively. In addition, the inhibition of tyrosinase activity was increased by the fermented samples from 29.33% to 41.74% following fermentation for up to 72 h. The tyrosinase activity of the untreated control group was increased to 145.69% in B16F10 cells. The results showed that I. britannica fermented by L. plantarum dose-dependently inhibited tyrosinase activity, which was stimulated by α-melanocyte stimulating hormone. These results suggest that lactic fermented I. britannica extracts can be used as effective skin-whitening materials.

Tricetin Induces Apoptosis of Human Leukemic HL-60 Cells through a Reactive Oxygen Species-Mediated c-Jun N-Terminal Kinase Activation Pathway

Tricetin is a dietary flavonoid with cytostatic properties and antimetastatic activities in various solid tumors. The anticancer effect of tricetin in nonsolid tumors remains unclear. Herein, the molecular mechanisms by which tricetin exerts its anticancer effects on acute myeloid leukemia (AML) cells were investigated. Results showed that tricetin inhibited cell viability in various types of AML cell lines. Tricetin induced morphological features of apoptosis such as chromatin condensation and phosphatidylserine (PS) externalization, and significantly activated proapoptotic signaling including caspase-8, -9, and -3 activation and poly(ADP-ribose) polymerase (PARP) cleavage in HL-60 AML cells. Of note, tricetin-induced cell growth inhibition was dramatically reversed by a pan caspase and caspase-8- and -9-specific inhibitors, suggesting that this compound mainly acts through a caspase-dependent pathway. Moreover, treatment of HL-60 cells with tricetin induced sustained activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), and inhibition of ERK and JNK by their specific inhibitors respectively promoted and abolished tricetin-induced cell apoptosis. Dichlorofluorescein (DCF) staining showed that intracellular reactive oxygen species (ROS) levels were higher in tricetin-treated HL-60 cells compared to the control group. Moreover, an ROS scavenger, N-acetylcysteine (NAC), reversed tricetin-induced JNK activation and subsequent cell apoptosis. In conclusion, our results indicated that tricetin induced cell death of leukemic HL-60 cells through induction of intracellular oxidative stress following activation of a JNK-mediated apoptosis pathway. A combination of tricetin and an ERK inhibitor may be a better strategy to enhance the anticancer activities of tricetin in AML.

Chemopreventive Agents and Inhibitors of Cancer Hallmarks: May Citrus Offer New Perspectives?

Fruits and vegetables have long been recognized as potentially important in the prevention of cancer risk. Thus, scientific interest in nutrition and cancer has grown over time, as shown by increasing number of experimental studies about the relationship between diet and cancer development. This review attempts to provide an insight into the anti-cancer effects of Citrus fruits, with a focus on their bioactive compounds, elucidating the main cellular and molecular mechanisms through which they may protect against cancer. Scientific literature was selected for this review with the aim of collecting the relevant experimental evidence for the anti-cancer effects of Citrus fruits and their flavonoids. The findings discussed in this review strongly support their potential as anti-cancer agents, and may represent a scientific basis to develop nutraceuticals, food supplements, or complementary and alternative drugs in a context of a multi-target pharmacological strategy in the oncology.