Myricetin induces pancreatic cancer cell death via the induction of apoptosis and inhibition of the phosphatidylinositol 3-kinase (PI3K) signaling pathway

Myricetin induces apoptosis and autophagy by inhibiting PI3K/Akt/mTOR signalling in human colon cancer cells

BACKGROUND

The compound 3,3',4',5,5',7-hexahydroxyflavone (myricetin) is a natural flavonoid with antitumour activity. Most of the studies on myricetin have focused on the induction of tumour cell apoptosis, and little is known about the regulatory effects of myricetin on autophagy in colorectal cancer.

METHODS

Here, we studied the effects of myricetin on colon cancer cell proliferation, apoptosis and autophagy. We detected colon cancer cell apoptosis induced by myricetin via flow cytometry and Hoechst 33258 staining. Transmission electron microscopy was performed to observe the morphological changes associated with autophagy. The expression levels of apoptosis-, autophagy- and PI3K/Akt/mTOR signalling-related proteins were measured by Western blot analysis.

RESULTS

This study confirmed that myricetin inhibits the proliferation of 4 kinds of colon cancer cell lines. Myricetin induced cell apoptosis and autophagy by inhibiting PI3K/Akt/mTOR signalling pathway. In addition, the inhibition of autophagy with 3-methyladenine (3-MA) promoted the apoptosis of myricetin-treated colon cancer cells.

CONCLUSIONS

Considering that myricetin induces apoptosis and autophagy in colon cancer cells, myricetin may become a viable candidate for chemotherapy; it could be used to exert tumour inhibitory effects alone or as adjuvant chemotherapy to inhibit autophagy. These studies may provide further evidence for the potential use of myricetin in the treatment of colon cancer.

In vitro and in vivo effects of the combination of myricetin and miconazole nitrate incorporated to thermosensitive hydrogels, on C. albicans biofilms

BACKGROUND

Candida albicans-related infections are common infections in clinic, among which biofilm-associated infections are most devastating and challenging to overcome. Myricetin (MY) is a plant-derived natural product with various pharmacological activities. Its anti-biofilm effect against C. albicans and its ability to increase the antifungal effect of miconazole nitrate (MN) were unclear and yet need to be explored.

HYPOTHESIS/PURPOSE

In this study the anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro and in vivo.

STUDY DESIGN AND METHODS

MY or/and MN were incorporated into a thermosensitive hydrogel (TSH) of poloxamer. The safety of MY or/and MN loaded TSHs towards human umbilical vein endothelial cells (HUVEC) was evaluated by a MTT assay and the in vivo safety towards mice knees was confirmed by histopathological examination. The anti-biofilm effect of MY and its ability to increase the antifungal effect of MN were investigated in vitro with C. albicans ATCC 10231 by broth microdilution method, crystal violet staining and scanning electron microscopy (SEM), as well as in vivo in an established mouse model of periprosthetic joint infection (PJI) by SEM, histological analysis, microorganism culture and detection of the serum levels of interleukin-6 (IL-6). The mechanism of action of MY was analyzed by qRT-PCR assay with C. albicans SC5314.

RESULTS

Our results showed that MY and MN incorporated into TSHs exhibited good stability and safety, excellent temperature sensitivity and controlled drug release property. MY (5-640 µg/ml) exhibited no effect on C. albicans cell viability and MY (≥80 µg/ml) showed a significantly inhibitory effect on biofilm formation. MIC₅₀ (the lowest concentrations of drugs resulting in 50% decrease of C. albicans growth) and MIC₈₀ (the lowest concentrations of drugs resulting in 80% decrease of C. albicans growth) of MN were respectively decreased from 2 µg/ml to 0.5 µg/ml and from 4 µg/ml to 2 µg/ml when used in combination with MY (80 µg/ml). The mouse PJI was effectively prevented by MY and MN incorporated into TSH.

CONCLUSIONS

Local application of MY and MN incorporated into TSH might be useful for clinical biofilm-associated infections.

A review on myricetin as a potential therapeutic candidate for cancer prevention

Myricetin, one of the most extensively studied polyphenols, is present abundantly in various fruits and vegetables and exhibits diverse pharmacological properties. The multifaceted biological action of myricetin against tumor heterogeneity makes it an impressive anticancer agent whose efficacy has been confirmed by an overwhelming number of studies. Myricetin shows its therapeutic potential by targeting and modulating the expression of various molecular target which are involved in inflammation, cell proliferation, apoptosis, angiogenesis, invasion, and metastasis. Myricetin deters tumor progression by inducing apoptosis via both intrinsic and extrinsic pathway, activating/inactivating several signaling pathways, and reactivating various tumor suppressor genes. This comprehensive review represents the effect of myricetin on various hallmarks of cancer with insight into the molecular mechanism employed by myricetin to mitigate cell proliferation, angiogenesis, metastasis, and induce apoptosis. In addition, enhanced bioavailability of myricetin through conjugation and its increased efficacy as an anticancer agent when used in combination are also highlighted.

Targeting PI3K/Akt/mTOR signaling pathway by polyphenols: Implication for cancer therapy

Cancer is one of the biggest challenges facing medicine and its cure is regarded to be the Holy Grail of medicine. Therapy in cancer is consisted as various artificial cytotoxic agents and radiotherapy, and recently immunotherapy. Recently much attention has been directed to the use of natural occurring agents in cancer therapy. One of the main group of agents utilized in this regard is polyphenols which are found abundantly in berries, fruits and vegetables. Polyphenols show to exert direct and indirect effects in progression of cancer, angiogenesis, proliferation and enhancing resistance to treatment. One of the cellular pathways commonly affected by polyphenols is PI3K/Akt/mTOR pathway, which has far ranging effects on multiple key aspects of cellular growth, metabolism and death. In this review article, evidence regarding the biology of polyphenols in cancer via PI3K/Akt/mTOR pathway is discussed and their application on cancer pathophysiology in various types of human malignancies is shown.

HSP70 Multi-Functionality in Cancer

The 70-kDa heat shock proteins (HSP70s) are abundantly present in cancer, providing malignant cells selective advantage by suppressing multiple apoptotic pathways, regulating necrosis, bypassing cellular senescence program, interfering with tumor immunity, promoting angiogenesis and supporting metastasis. This direct involvement of HSP70 in most of the cancer hallmarks explains the phenomenon of cancer "addiction" to HSP70, tightly linking tumor survival and growth to the HSP70 expression. HSP70 operates in different states through its catalytic cycle, suggesting that it can multi-function in malignant cells in any of these states. Clinically, tumor cells intensively release HSP70 in extracellular microenvironment, resulting in diverse outcomes for patient survival. Given its clinical significance, small molecule inhibitors were developed to target different sites of the HSP70 machinery. Furthermore, several HSP70-based immunotherapy approaches were assessed in clinical trials. This review will explore different roles of HSP70 on cancer progression and emphasize the importance of understanding the flexibility of HSP70 nature for future development of anti-cancer therapies.

Folic acid (FA)-conjugated mesoporous silica nanoparticles combined with MRP-1 siRNA improves the suppressive effects of myricetin on non-small cell lung cancer (NSCLC)

Non-small cell lung cancer (NSCLC) is a common diagnosed cancer disease worldwide and its management remains a challenge. Synergistic cancer therapeutic strategy is interesting for multiple advantages, such as excellent targeting accuracy, low side effects, and promoted therapeutic efficiency. In the present study, myricetin (Myr)-loaded mesoporous silica nanoparticles (MSN) combined with multidrug resistance protein (MRP-1) siRNA was prepared. The surface of the synthesized nanoparticles was modified with folic acid (FA) to promote the therapeutic efficiency of Myr for the treatment of NSCLC. The collected particles were nano-sized and showed a sustained release of Myr in the physiological conditions. FA-conjugated nanoformulations displayed a significant uptake in lung cancer cells compared with that of the non-targeted nanoparticles. The in vitro drug release results suggested a sustained release in FA-conjugated MSN with Myr and MRP-1 nanoparticles compared to the free Myr and MSN combined with MRP-1/Myr. Treatments with FA-conjugated MSN combined with Myr and MRP-1 markedly reduced the cell viability of lung cancer cell lines, including A549 and NCI-H1299, which was accompanied with the decreased number of colony formation. In addition, FA-conjugated MSN loaded with Myr and MRP-1 significantly induced apoptosis in lung cancer cells, along with up-regulated expression levels of cleaved Caspase-3 and PARP. In vivo fluorescence results demonstrated that FA-conjugated MSN with Myr and MRP-1 nanoparticles could specifically accumulate at tumor sites. Compared with free Myr and MSN combined with MRP-1/Myr nanoparticles, FA-conjugated MSN loaded with Myr and MRP-1 nanoparticles could more effectively suppress tumor growth with little side effects. Overall, FA-conjugated nanoparticulate system could provide a novel and effective platform for the treatment of NSCLC.

Bioflavonoids cause DNA double-strand breaks and chromosomal translocations through topoisomerase II-dependent and -independent mechanisms

Bioflavonoids have a similar chemical structure to etoposide, the well-characterized topoisomerase II (Top2) poison, and evidence shows that they also induce DNA double-strand breaks (DSBs) and promote genome rearrangements. The purpose of this study was to determine the kinetics of bioflavonoid-induced DSB appearance and repair, and their dependence on Top2. Cells were exposed to bioflavonoids individually or in combination in the presence or absence of the Top2 catalytic inhibitor dexrazoxane. The kinetics of appearance and repair of γH2AX foci were measured. In addition, the frequency of resultant MLL-AF9 breakpoint cluster region translocations was determined. Bioflavonoids readily induced the appearance of γH2AX foci, but bioflavonoid combinations did not act additively or synergistically to promote DSBs. Myricetin-induced DSBs were mostly reduced by dexrazoxane, while genistein and quercetin-induced DSBs were only partially, but significantly, reduced. By contrast, luteolin and kaempferol-induced DSBs increased with dexrazoxane pre-treatment. Sensitivity to Top2 inhibition correlated with a significant reduction of bioflavonoid-induced MLL-AF9 translocations. These data demonstrate that myricetin, genistein, and quercetin act most similar to etoposide although with varying Top2-dependence. By contrast, luteolin and kaempferol have distinct kinetics that are mostly Top2-independent. These findings have implications for understanding the mechanisms of bioflavonoid activity and the potential of individual bioflavonoids to promote chromosomal translocations. Further, they provide direct evidence that specific Top2 inhibitors or targeted drugs could be developed that possess less leukemic potential or suppress chromosomal translocations associated with therapy-related and infant leukemias.

Sensitization of MDA-MBA231 breast cancer cell to docetaxel by myricetin loaded into biocompatible lipid nanoparticles via sub-G1 cell cycle arrest mechanism

The harmful dose-dependent side effects of chemotherapy drugs have caused the discovery of novel perspective to evaluate chemotherapy protocols. In this study, the potential application of Compritol was investigated as a major scaffold into nanostructured lipid careers to highlight myricetin efficiency in treatment of breast cancer cells along with codelivery of docetaxel (DXT). Characterization of myricetin-loaded NLCs was carried out by measuring the particle size and zeta potential, using the scanning electron microscopy. MTT, DAPI staining, flow cytometric, and RT-PCR (real-time) assays were used to recognize novel formulation behavior on cell cytotoxicity as well as recognizing molecular mechanism of formulation concerning apoptosis phenomenon. Myricetin-loaded NLCs reduced the cell viability from 50 ± 2.3 to 40 ± 1.3% (p < 0.05). Percentage of apoptosis improved with combination treatment of myricetin-loaded NLCs and DXT in the MDA-MBA231 breast cancer cells. Expression of antiapoptotic genes (survivin, Cyclin B1, and Mcl1) indicated a significant reduction in factor along with increment in proapoptotic factor Bax and Bid mRNA rates. Overall, our results represented that the NLC delivery system could be a promising strategy to enhance the effect of anticancer agents such as DXT on breast cancer.

Myricetin inhibits endometriosis growth through cyclin E1 down-regulation in vitro and in vivo

Endometriosis is a benign gynecological condition prevalent among reproductive-aged women. Although active research and studies have been carried out to discover new drugs, surgery and hormone therapy are still the gold standard for endometriosis treatment. Nowadays, various flavonoids are considered long-term supplements for different diseases. Myricetin, a flavonol, has antiproliferative, anti- or pro-oxidant, and anticancer effects in gynecological diseases. Here, we reveal for the first time, to our knowledge, the antigrowth effects of myricetin in endometriosis. Myricetin inhibited cell proliferation and cell cycle progression of human VK2/E6E7 and End1/E6E7 cells and induced apoptosis, with the loss of mitochondrial membrane potential and accumulation of reactive oxygen species and calcium ions. Additionally, myricetin decreased the activation of AKT and ERK1/2 proteins, whereas it induced p38 activation in both cell lines. Moreover, myricetin decreased lesion size in the endometriosis mouse model via Ccne1 inhibition. Thus, myricetin has antiproliferative effects on endometriosis through cell cycle regulation.

Myricetin ameliorates high glucose-induced endothelial dysfunction in human umbilical vein endothelial cells

Endothelial dysfunction is recognized as the initial detectable stage of cardiovascular disease, a serious complication of diabetes. In this study, we evaluated effects of myricetin on high glucose (HG)-elicited oxidative damage in human umbilical vein endothelial cells (HUVECs). The cells were pre-incubated with myricetin and then treated with HG to induce apoptosis. The effect of myricetin on viability was investigated by MTT assay. The levels of lipid peroxidation (LPO) were determined by thiobarbituric acid (TBA) method. The protein expression of Bax, Bcl-2 and caspase-3 was measured by western blot analysis. Moreover, the effect of myricetin on total antioxidant capacity (TAC) and total thiol molecules was also determined. Our results showed that myricetin was able to markedly restore the viability of endothelial cells under oxidative stress. Myricetin reduced HG-caused increase in LPO levels. Also, TAC and total thiol molecules were notably elevated by myricetin. Incubation with myricetin decreased the protein expression levels of Bax, whereas it increased the expression levels of the Bcl-2, compared with HG treatment alone. Furthermore, myricetin significantly decreased cleaved caspase-3 protein expression. It is concluded that myricetin may protect HUVECs from oxidative stress induced by HG via increasing cell TAC and reducing Bax/Bcl-2 protein ratio, and caspase-3 expression.

Function of flavonoids on different types of programmed cell death and its mechanism: a review

Cell death in the living system plays a vital role in maintaining the homeostasis and balancing the cell count in the body. Programmed cell death (PCD) is a crucial component of several development and defense mechanisms. PCD is also important in terms of aging which avoids the accumulation of cellular damage by maintaining cell division. Depending on the execution of cell death and its role in destruction, PCD is categorized into several subtypes. The major different forms of PCD in animals are apoptosis, autophagy and necrosis, which can be distinct in morphological terms. More intense investigations of cell death have given close insight showing other important types of cellular destruction and their pivotal roles in treating disease conditions like cancer. Flavonoids have been acquired a great interest for disease therapies and chemoprevention through activation of several PCD mechanisms. The significant potential of natural flavonoids in the induction of distinct signaling cascades is being a massive approach for targeting uncontrolled cell growth. For these reasons, understanding PCD mechanisms is a promising approach for the interventions in treating cancer. Thus, it is intriguing that understanding the different forms of PCD mechanism induced by flavonoids with more accurate descriptions on the biochemical and cellular processes are gaining more significance in cancer research. Here, we provide a brief overview on the different types of PCD and aim to discuss the functional role of flavonoids in promoting different types of cell death as well as an extensive brief review on their mechanism of action has been highlighted.

Anti-tumor effects and associated molecular mechanisms of myricetin

Myricetin (3, 5, 7, 3', 4', 5'-hexahydroxyflavone) is a natural flavonol compound found in a large variety of plants, including berries, oranges, grapes, herbs, teas, and wine. In the last decade, a convergence of evidence has demonstrated that myricetin has good biological activity as an anti-tumor, anti-inflammatory, and anti-oxidation agent. In studies involving various types of cancer cells, myricetin has been shown to suppress cancer cell invasion and metastasis, to induce cell cycle arrest and apoptosis of cancer cells, and to inhibit their proliferation. These findings have raised interest in myricetin as a potential tumor inhibitor in human patients. In this review, evidence of myricetin's anti-tumor activity and its underlying molecular mechanisms published in the last decade are summarized.

Potential proapoptotic phytochemical agents for the treatment and prevention of colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of mortality among men and women. Chemo-resistance, adverse effects and disease recurrence are major challenges in the development of effective cancer therapeutics. Substantial literature on this subject highlights that populations consuming diets rich in fibers, fruits and vegetables have a significantly reduced incidence rate of CRC. This chemo-preventive effect is primarily associated with the presence of phytochemicals in the dietary components. Plant-derived chemical agents act as a prominent source of novel compounds for drug discovery. Phytochemicals have been the focus of an increasing number of studies due to their ability to modulate carcinogenic processes through the alteration of multiple cancer cell survival pathways. Despite promising results from experimental studies, only a limited number of phytochemicals have entered into clinical trials. The purpose of the current review is to compile previously published pre-clinical and clinical evidence of phytochemicals in cases of CRC. A PubMed, Google Scholar and Science Direct search was performed for relevant articles published between 2008-2018 using the following key terms: 'Phytochemicals with colorectal cancers', 'apoptosis', 'cell cycle', 'reactive oxygen species' and 'clinical anticancer activities'. The present review may aid in identifying the most investigated phytochemicals in CRC cells, and due to the limited number of studies that make it from the laboratory bench to clinical trial stage, may provide a novel foundation for future research.

Identification of MRP2 as a targetable factor limiting oxaliplatin accumulation and response in gastrointestinal cancer

Oxaliplatin is important for the clinical treatment of colorectal cancer and other gastrointestinal malignancies, but tumour resistance is limiting. Several oxaliplatin transporters were previously identified but their relative contributions to determining oxaliplatin tumour responses and gastrointestinal tumour cell sensitivity to oxaliplatin remains unclear. We studied clinical associations between tumour expression of oxaliplatin transporter candidate genes and patient response to oxaliplatin, then experimentally verified associations found with MRP2 in models of human gastrointestinal cancer. Among 18 oxaliplatin transporter candidate genes, MRP2 was the only one to be differentially expressed in the tumours of colorectal cancer patients who did or did not respond to FOLFOX chemotherapy. Over-expression of MRP2 (endogenously in HepG2 and PANC-1 cells, or induced by stable transfection of HEK293 cells) decreased oxaliplatin accumulation and cytotoxicity but those deficits were reversed by inhibition of MRP2 with myricetin or siRNA knockdown. Mice bearing subcutaneous HepG2 tumour xenografts were sensitised to oxaliplatin antitumour activity by concurrent myricetin treatment with little or no increase in toxicity. In conclusion, MRP2 limits oxaliplatin accumulation and response in human gastrointestinal cancer. Screening tumour MRP2 expression levels, to select patients for treatment with oxaliplatin-based chemotherapy alone or in combination with a MRP2 inhibitor, could improve treatment outcomes.

Screening of cytotoxic or cytostatic flavonoids with quantitative Fluorescent Ubiquitination-based Cell Cycle Indicator-based cell cycle assay

The Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI) system can be used not only to study gene expression at a specific cell cycle stage, but also to monitor cell cycle transitions in real time. In this study, we used a single clone of FUCCI-expressing HeLa cells (FUCCI-HeLa cells) and monitored the cell cycle in individual live cells over time by determining the ratios between red fluorescence (RF) of RFP-Cdt1 and green fluorescence (GF) of GFP-Geminin. Cytotoxic and cytostatic compounds, the latter of which induced G2 or mitotic arrest, were identified based on periodic cycling of the RF/GF and GF/RF ratios in FUCCI-HeLa cells treated with anti-cancer drugs. With this cell cycle monitoring system, ten flavonoids were screened. Of these, apigenin and luteolin, which have a flavone backbone, were cytotoxic, whereas kaempferol, which has a flavonol backbone, was cytostatic and induced G2 arrest. In summary, we developed a system to quantitatively monitor the cell cycle in real time. This system can be used to identify novel compounds that modulate the cell cycle and to investigate structure-activity relationships.

Postgenomic Properties of Natural Micronutrients

Modern medical approaches to the therapy of various diseases, including cancer, are based on the use of toxic drugs. The unfavorable side effects of traditional medicine could be counterbalanced by addition of natural bioactive substances to conventional therapy due to their mild action on cells combined with the multitargeted effects. To elucidate the real mechanisms of their biological activity, versatile approaches including a number of "omics" such as genomics, transcriptomics, proteomics, and metabolomics are used. This review highlights inclusion of bioactive natural compounds into the therapy of chronic diseases from the viewpoint of modern omics-based nutritional biochemistry. The recently accumulated data argue for necessity to employ nutrigenetic and nutrimetabolomic analyses to prevent or diminish the risk of chronic diseases.

An Array of Bioactive Compounds From Australian Eucalypts and Their Relevance in Pancreatic Cancer Therapeutics

Pancreatic cancer (PC) is one of the most devastating human cancers, and despite the significant advances in the current therapeutic options, the overall survival rate for PC has remained static for the past 50 years. Plant-derived bioactive compounds play a vital role in cancer therapeutics by providing new lead compounds for future drug development. Therefore, the isolation, characterization, and identification of new bioactive compounds for the prevention and treatment of cancer continue to be an important aspect of natural product research. Many in vitro and in vivo studies published in the last few decades have established strong links between the phytochemical profile of eucalypts and anticancer activity. However, only a small number of these reports have attempted to demonstrate a relationship between the biological activity of eucalypt extracts and PC. This review focuses on potential anti-PC effects of an array of bioactive compounds present in various species of eucalypts. It also highlights the necessity for further in vitro and in vivo studies to develop a complete understanding of the potential this group of plants has for the development of potent and specific chemotherapeutic drugs for PC.

Eucalyptus microcorys leaf extract derived HPLC-fraction reduces the viability of MIA PaCa-2 cells by inducing apoptosis and arresting cell cycle

New therapeutic strategies such as the development of novel drugs and combinatorial therapies with existing chemotherapeutic agents are urgently needed to improve the clinical prognosis of pancreatic cancer. We have previously reported the antiproliferative properties of aqueous crude Eucalyptus microcorys extract against pancreatic cancer cell lines. In this study, bioassay-guided fractionation of the aqueous crude E. microcorys extract using RP-HPLC and subsequent assessment of the resultant fractions (F1-F5) for their antioxidant activity and cytotoxicity against pancreatic cancer cell lines were performed. The molecular mechanisms associated with the cytotoxicity was characterised by studying the effects of the most potent fraction-1 (F1) on apoptosis and cell cycle profiles as well as its phytochemical constituents by LC-ESI/MS/MS. F1 displayed significantly greater antioxidant activity in three different assays (p < 0.05). Moreover, F1 exhibited significantly greater antiproliferative activity (IC₅₀ = 93.11 ± 3.43 μg/mL) against MIA PaCa-2 cells compared to the other four fractions (p < 0.05). F1 induced apoptosis by regulating key apoptotic proteins- Bcl-2, Bak, Bax, cleaved PARP, procaspase-3 and cleaved caspase-3 in MIA PaCa-2 cells, suggesting the involvement of intrinsic mitochondrial apoptotic pathway and arrested cells at G2/M phase. A combination of gemcitabine and F1 exerted a greater effect on apoptosis and cell cycle arrest than F1 or gemcitabine alone (p < 0.05). LC-ESI/MS/MS revealed the tentative identities of phytochemicals present in F1 and their similarities with the phenolic compounds previously reported in Eucalyptus with antipancreatic cancer activity. Our study shows that the polyphenol and antioxidant-rich fraction of E. microcorys extract is a promising candidate for developing mono or combination therapies against pancreatic cancer.

Induction of apoptosis and cell cycle arrest by ethyl acetate fraction of Phoenix dactylifera L. (Ajwa dates) in prostate cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Phoenix dactylifera L. (Ajwa date) has high nutritive value and are consumed in Arabian Peninsula as an essential diet. Phoenix dactylifera L. have been mentioned in folk remedies of traditional Egyptian medicine and alternative medicine, for numerous health benefits including cancer treatment. The aim of the study is to evaluate the anticancer effects of the extract of Ajwa Date on human Prostate cancer cell line (PC3).

MATERIALS AND METHODS

Antiproliferative effect was measured using MTT assay. The long-term effect of EAFAD was determined using colony assay. Different stains like Giemsa and fluorescent stains (DAPI and acridine orange / Ethidium bromide) measured morphological changes. Loss of mitochondrial membrane potential and increased oxidative stress were measured using JC-1 and DCFH-DA dyes. DNA degradation was analyzed by comet assay. Cell cycle distribution was measured by flow cytometer. The apoptotic cell was quantified by annexin V-FITC and Propidium iodide dual staining using flow cytometer.

RESULTS

PC3 cell line was treated with ethyl acetate fractions of Ajwa dates (EAFAD) to study their morphological and cellular changes and induction of apoptosis. MTT assay showed the strong inhibitory effect of EAFAD on PC3 cells. Loss of mitochondrial membrane potential and increased oxidative stress were observed in EAFAD treated cells, which suggested mitochondrial involvement in apoptosis. Comet assay proved DNA fragmentation induced by EAFAD. Flow Cytometer results demonstrated that Annexin V-FITC and propidium iodide staining showed that EAFAD induced apoptosis and arrest the cell cycle in S phase.

CONCLUSION

Our results suggested EAFAD has potential therapeutics properties for prostate cancer.

Myricetin-induced apoptosis of triple-negative breast cancer cells is mediated by the iron-dependent generation of reactive oxygen species from hydrogen peroxide

Myricetin is a dietary phytochemical with anticancer activity; however, the effect of myricetin on breast cancer cells remains unclear. Here, we show that myricetin inhibited the growth of triple-negative breast cancer (TNBC) cells but was less inhibitory for normal cells. The effect of myricetin was comparable to epigallocatechin gallate and doxorubicin, and greater than resveratrol and cisplatin. Myricetin-treated TNBC cells showed evidence of early and late apoptosis/necrosis, which was associated with intracellular reactive oxygen species (ROS) accumulation, extracellular regulated kinase 1/2 and p38 mitogen-activated protein kinase activation, mitochondrial membrane destabilization and cytochrome c release, and double-strand DNA breaks. The antioxidant N-acetyl-cysteine protected myricetin-treated TNBC cells from cytotoxicity due to DNA damage. Myricetin also induced hydrogen peroxide (H₂O₂) production in cell-free culture medium, as well as in the presence of TNBC cells and normal cells. In addition, deferiprone-mediated inhibition of intracellular ROS generation via the iron-dependent Fenton reaction and inhibition of extracellular ROS accumulation with superoxide dismutase plus catalase prevented myricetin-induced cytotoxicity in TNBC cell cultures. We conclude that the cytotoxic effect of myricetin on TNBC cells was due to oxidative stress initiated by extracellular H₂O₂ formed by autoxidation of myricetin, leading to intracellular ROS production via the Fenton reaction.

Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes

Trans-plasma membrane electron transport (tPMET) plays a role in protection of cells from intracellular reductive stress as well as protection from damage by extracellular oxidants. This process of transporting electrons from intracellular reductants to extracellular oxidants is not well defined. Here we present spectrophotometric assays by C2C12 myotubes to monitor tPMET utilizing the extracellular electron acceptors: water-soluble tetrazolium salt-1 (WST-1) and 2,6-dichlorophenolindophenol (DPIP or DCIP). Through reduction of these electron acceptors, we are able to monitor this process in a real-time analysis. With the addition of enzymes such as ascorbate oxidase (AO) and superoxide dismutase (SOD) to the assays, we can determine which portion of tPMET is due to ascorbate export or superoxide production, respectively. While WST-1 was shown to produce stable results with low background, DPIP was able to be re-oxidized after the addition of AO and SOD, which was demonstrated with spectrophotometric analysis. This method demonstrates a real-time, multi-well, quick spectrophotometric assay with advantages over other methods used to monitor tPMET, such as ferricyanide (FeCN) and ferricytochrome c reduction.

Myricetin Induces Protective Autophagy by Inhibiting the Phosphorylation of mTOR in HepG2 Cells

Myricetin, a natural flavonoid present in a variety of fruits and vegetables, has been studied as a promising cancer chemopreventive agent in many cancer models. It has been reported that myricetin could inhibit tumor promotion by inducing cell cycle arrest and promoting apoptotic cell death. At present, autophagy is considered to be closely associated with cancer, functioning as either an anti-cancer or pro-cancer mechanism depending on the cancer stage. Till date, the role of myricetin in regulating autophagy has not been reported. In this study, we found that myricetin can induce autophagy by inhibiting mTOR activation in HepG2 cells. Our findings thus provide evidence for further research and application of myricetin as a potential cancer therapeutic agent. Anat Rec, 301:786-795, 2018. © 2017 Wiley Periodicals, Inc.

Potential role of nucleoside diphosphate kinase in myricetin-induced selective apoptosis in colon cancer HCT-15 cells

The flavonoid myricetin (MYR) is derived from vegetables and fruits. It has been shown to exert anti-cancer effects in various cell lines; however, the exact mechanism underlying these effects is yet to be elucidated. In this study, we evaluated the anti-cancer effects induced by MYR treatment in colon cancer HCT-15 cells. To detect cell proliferation, we conducted MTT assay and real time-cell electronic sensing (RT-CES). We next performed comet assay and Annexin V and PI staining to detect cellular apoptotic features. After that, we conducted two-dimensional electrophoresis (2-DE) analysis to identify apoptotic proteins. The results of this analysis revealed that eight spots were differentially expressed. Among the spots, we selected nucleoside diphosphate kinase (NDPK) for further investigation, as it has been shown to regulate cancer cell apoptosis and metastasis. After that, we conducted realtime-PCR and western blot to detect the expression of NDPK mRNA and protein and wound-healing assay to detect cell migration and invasion. Finally, we performed NDPK siRNA transfection study and the results showed that NDPK knockdown inhibited apoptosis. Based on these collective results, we suggest that MYR induces apoptosis in human colon cancer HCT-15 cells selectively by increasing the expression of NDPK and other caspase-regulated apoptosis proteins.

Morphological and molecular effects of phenolic extract from coconut kernel on human prostate cancer cell growth in vitro

Coconut is an indispensable ingredient in the diet and traditional medicine of individuals belonging to the Indian subcontinent. Coconut is of high nutritional value owing to the presence of all essential dietary components, viz, saturated fatty acids, arginine rich proteins, fibre and minor components like vitamin E, phytosterols, polyphenols and flavonoids. The polyphenolic content present in coconut kernel is of particular interest due to their numerous reported beneficial effects such as reduction of oxidative stress, combating cancer and in modulating anti-inflammatory pathways. Therefore, in the present study the cytotoxic effect of the polyphenol rich fraction from coconut kernel (CKf) was evaluated in human prostate cancer (DU-145) cells. Individual components present in CKf was determined by LC-MS analysis. It showed that CKf contained several bioactive molecules which have potential anticancer activity viz, coumaric acid, myristin, chlorogenic acid and triterpenoid methyl esters. The cytotoxic effect of CKf at various concentrations (2.5–20 μg/ml) on DU-145 was assessed using MTT assay, AO/EB staining, mitochondrial superoxide/ROS production and changes in intracellular calcium levels, 24 hrs post treatment. Changes in the cell morphology and nucleus were observed using Scanning Electron Microscopy and Confocal microscopy. ROS and mitochondrial superoxide levels was evaluated using DCHF-DA and MitoSOX staining respectively. The impact of ROS on changes in cellular calcium levels was also studied using Fura-2-AM. LDH leakage from C K f treated and control cells were observed colorimetrically. Further, PCR analysis was done to detect changes in mitochondria associated apoptotic gene expression. It was also observed that C K f treatment increased the expression of pro-apoptotic genes - Bax, Bid, Bak and p53 in a dose-dependent manner. Based on the above results, it can be concluded that C K  f may be used as a part of a dietary regime for controlling the progression of prostate cancer.

Sulforaphane and myricetin act synergistically to induce apoptosis in 3T3‑L1 adipocytes

The aim of the present study was to investigate whether sulforaphane (SFN) and myricetin (Myr) synergistically induce apoptosis in adipocytes. The viability of mature 3T3-L1 adipocytes treated with 40 µM SFN and/or 100 µM Myr was assessed using an MTT assay. Apoptosis was assessed by Hoechst 33258 nuclear staining, and by detection of single-stranded DNA using an enzyme-linked immunosorbent assay. Compared with the effects of each compound alone, the combination of SFN and Myr synergistically reduced cell viability, induced apoptosis, increased pro-apoptotic Bcl-2 associated X protein expression, decreased anti-apoptotic B-cell lymphoma-2 expression, enhanced Bcl-2-associated death promoter (Bad) translocation from the cytoplasm to the mitochondria, and reduced Bad phosphorylation at Ser112. These effects were accompanied by increased cleavage of caspase 3 and poly-ADP-ribose-polymerase. In addition, combined SFN and Myr treatment significantly decreased the protein expression levels of phosphorylated AKT serine/threonine kinase 1 (Akt) at Ser473, as well as the phosphorylation of the downstream protein ribosomal protein, S6 kinase β-1. Therefore, SFN plus Myr was a more potent inducer of apoptosis in 3T3-L1 adipocytes than either compound alone. The results of the present study suggest that the mechanism of SNF/Myr-induced apoptosis involved activation of the Akt-mediated mitochondrial apoptotic pathway. This may aid treatment of animal models of obesity and preclinical testing.

Synthesis and biological activity of myricetin derivatives containing 1,3,4-thiadiazole scaffold

BACKGROUND

Myricetin and 1,3,4-thiadiazole derivatives were reported to exhibit favorable antiviral and antibacterial activities. Aiming to discover novel myricetin analogues with potent activities, a series of novel myricetin derivatives containing 1,3,4-thiadiazole moiety were synthesized, and their antibacterial and antiviral activities were evaluated.

RESULT

Bioassay results indicated that some target compounds exhibited potential antibacterial and antiviral activities. Among them, compounds 2, 3a, 3b, 3d, 3f, 3i, 3m and 3p exhibited excellent antibacterial activities against Xanthomonas oryzae pv. Oryzae (Xoo), with EC₅₀ values of 42.7, 38.6, 20.8, 12.9, 22.7, 27.3, 18.3 and 29.4 μg/mL, respectively, which were better than that of thiadiazole-copper (94.9 μg/mL). Compounds 3b, 3d, 3e, 3f, 3i and 3o showed good antibacterial activities against Ralstonia solanacearum (Rs), with EC₅₀ values of 37.9, 72.6, 43.6, 59.6, 60.6 and 39.6 μg/mL, respectively, which were superior to that of thiadiazole-copper (131.7 μg/mL). In addition, compounds 3d, 3f, 3i and 3m showed better curative activities against tobacco mosaic virus (TMV), with EC₅₀ values of 152.8, 99.7, 127.1, and 167.3 μg/mL, respectively, which were better than that of ningnanmycin (211.1 μg/mL).

CONCLUSIONS

A series of myricetin derivatives containing 1,3,4-thiadiazole scaffold were synthesized, and their antibacterial activities against Xoo and Rs and their antiviral activity against TMV were evaluated. Bioassays indicated that some target compounds exhibited potential antibacterial and antiviral activities. These results indicated this kind of myricetin analogues could be further studied as potential alternative templates in the search for novel antibacterial and antiviral agents.

(2R,3S,2″R,3″R)-Manniflavanone Protects Proliferating Skeletal Muscle Cells against Oxidative Stress and Stimulates Myotube Formation

We investigated the antioxidative properties of (2R,3S,2″R,3″R)-manniflavanone (MF) using in vitro assays and examined its effects on myogenesis and lactate-induced oxidative stress in C2C12 cells. MF was purified from Garcinia buchananii stem bark. H₂O₂ and oxygen radical absorbance capacity assays demonstrated that MF is a powerful antioxidant. This finding was supported by diphenylpicrylhydrazine radical scavenging activity of MF. MF was less cytotoxic to C2C12 cells compared to ascorbic acid and myricetin. Moreover, MF accelerated myotube formation in the differentiated C2C12 cells by up-regulating myogenic proteins such as MyoG and myosin heavy chain. Furthermore, MF rescued late differentiation of myoblast suppressed by lactate treatment and up-regulated the expression levels of Nrf2 in lactate-induced oxidative stress, indicating that MF stimulates antioxidative activity inside C2C12 cells. Collectively, MF is a potent antioxidant with a higher safety profile than ascorbic acid and myricetin. It reduces oxidative stress-induced delaying of skeletal muscle differentiation by scavenging reactive oxygen species and regulating myogenic proteins factors.

In vitro anticancer properties of selected Eucalyptus species

In spite of the recent advancements in oncology, the overall survival rate for pancreatic cancer has not improved over the last five decades. Eucalypts have been linked with cytotoxic and anticancer properties in various studies; however, there is very little scientific evidence that supports the direct role of eucalypts in the treatment of pancreatic cancer. This study assessed the anticancer properties of aqueous and ethanolic extracts of four Eucalyptus species using an MTT assay. The most promising extracts were further evaluated using a CCK-8 assay. Apoptotic studies were performed using a caspase 3/7 assay in MIA PaCa-2 cells. The aqueous extract of Eucalyptus microcorys leaf and the ethanolic extract of Eucalyptus microcorys fruit inhibited the growth of glioblastoma, neuroblastoma, lung and pancreatic cancer cells by more than 80% at 100 μg/mL. The E. microcorys and Eucalyptus saligna extracts showed lower GI₅₀ values than the ethanolic Eucalyptus robusta extract in MIA PaCa-2 cells. Aqueous E. microcorys leaf and fruit extracts at 100 μg/mL exerted significantly higher cell growth inhibition in MIA PaCa-2 cells than other extracts (p < 0.05). Statistically similar IC₅₀ values (p > 0.05) were observed in aqueous E. microcorys leaf (86.05 ± 4.75 μg/mL) and fruit (64.66 ± 15.97 μg/mL) and ethanolic E. microcorys leaf (79.30 ± 29.45 μg/mL) extracts in MIA PaCa-2 cells using the CCK-8 assay. Caspase 3/7-mediated apoptosis and morphological changes of cells were also witnessed in MIA PaCa-2 cells after 24 h of treatment with the extracts. This study highlighted the significance of E. microcorys as an important source of phytochemicals with efficacy against pancreatic cancer cells. Further studies are warranted to purify and structurally identify individual compounds and elucidate their mechanisms of action for the development of more potent and specific chemotherapeutic agents for pancreatic cancer.

Functional Vegetable Guar (Cyamopsis tetragonoloba L. Taub.) Accessions for Improving Flavonoid Concentrations in Immature Pods

Dry guar (Cyamopsis tetragonoloba L. Taub) seeds are primarily used to extract galactomannan gum for oil fracking, however, the immature pods are used as a vegetable in India and sold in ethnic grocery stores in the Atlanta, Georgia area. Nineteen guar genotypes were grown in the field at Griffin, GA, USA for two years (2010-2011). Since the determination of flavonoid concentration would add value to the guar accessions for use as a functional food vegetable, immature guar pods were evaluated for flavonoid concentration. In this study, the immature pods from these 19 guar accessions were analyzed for flavonoid concentration using high-performance liquid chromatography. Several accessions including PI 253182, PI 262152, PI 263698, and PI 288357 showed significantly greater daidzein concentration than all three controls based on seed production in 2010. However, PI 179926, PI 180434, PI 182969, PI 183400, PI 253182, PI 262152, PI 263882, and PI 263897 exhibited significantly greater genistein concentration than the second and third best controls in 2011. Both PI 180434 and PI 288359 produced significantly higher kaempferol concentration than the third best control. Daidzein concentration was significantly correlated with genistein concentration (r² = 0.47*) for both years. Luteolin concentration showed a significant negative correlation with genistein (r² = -0.45*). Quercetin concentration significantly correlated with kaempferol (r² = 0.854***) and genistein (r² = 0.455*) concentrations. The accession, PI 542608 was observed to contain high concentrations of kaempferol and quercetin in the cluster analyses. These results will help plant breeders develop guar cultivars with superior flavonoid concentrations.

Ajwa Date (Phoenix dactylifera L.) Extract Inhibits Human Breast Adenocarcinoma (MCF7) Cells In Vitro by Inducing Apoptosis and Cell Cycle Arrest

Introduction

Phoenix dactylifera L (Date palm) is a native plant of the Kingdom of Saudi Arabia (KSA) and other Middle Eastern countries. Ajwa date has been described in the traditional and alternative medicine to provide several health benefits including anticholesteremic, antioxidant, hepatoprotective and anticancer effects, but most remains to be scientifically validated. Herein, we evaluated the anticancer effects of the Methanolic Extract of Ajwa Date (MEAD) on human breast adenocarcinoma (MCF7) cells in vitro.

Methods

MCF7 cells were treated with various concentrations (5, 10, 15, 20 and 25 mg/ml) of MEAD for 24, 48 and 72 h and changes in cell morphology, cell cycle, apoptosis related protein and gene expression were studied.

Results

Phase contrast microscopy showed various morphological changes such as cell shrinkage, vacuolation, blebbing and fragmentation. MTT (2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay demonstrated statistically significant dose-dependent inhibitions of MCF7 cell proliferation from 35% to 95%. Annexin V-FITC and TUNEL assays showed positive staining for apoptosis of MCF7 cells treated with MEAD (15 mg and 25 mg for 48 h). Flow cytometric analyses of MCF7 cells with MEAD (15 mg/ml and 20 mg/ml) for 24 h demonstrated cell cycle arrest at 'S' phase; increased p53, Bax protein expression; caspase 3activation and decreased the mitochondrial membrane potential (MMP). Quantitative real time PCR (qRT-PCR) analysis showed up-regulation of p53, Bax, Fas, and FasL and down-regulation of Bcl-2.

Conclusions

MEAD inhibited MCF7 cells in vitro by the inducing cell cycle arrest and apoptosis. Our results indicate the anticancer effects of Ajwa dates, which therefore may be used as an adjunct therapy with conventional chemotherapeutics to achieve a synergistic effect against breast cancer.

Myricetin is a novel inhibitor of human inosine 5'-monophosphate dehydrogenase with anti-leukemia activity

Human inosine 5'-monophosphate dehydrogenase (hIMPDH) is a rate-limiting enzyme in the de novo biosynthetic pathway of purine nucleotides, playing crucial roles in cellular proliferation, differentiation, and transformation. Dysregulation of hIMPDH expression and activity have been found in a variety of human cancers including leukemia. In this study, we found that myricetin, a naturally occurring phytochemical existed in berries, wine and tea, was a novel inhibitor of human type 1 and type 2 IMPDH (hIMPDH1/2) with IC50 values of 6.98 ± 0.22 μM and 4.10 ± 0.14 μM, respectively. Enzyme kinetic analysis using Lineweaver-Burk plot revealed that myricetin is a mix-type inhibitor for hIMPDH1/2. Differential scanning fluorimetry and molecular docking simulation data demonstrate that myricetin is capable of binding with hIMPDH1/2. Myricetin treatment exerts potent anti-proliferative and pro-apoptotic effects on K562 human leukemia cells in a dose-dependent manner. Importantly, cytotoxicity of myricetin on K562 cells were markedly attenuated by exogenous addition of guanosine, a salvage pathway of maintaining intracellular pool of guanine nucleotides. Taking together, these results indicate that natural product myricetin exhibits potent anti-leukemia activity by interfering with purine nucleotides biosynthetic pathway through the suppression of hIMPDH1/2 catalytic activity.

Antioxidant activity of polyphenolic myricetin in vitro cell- free and cell-based systems

Myricetin (Myc) is one of the most important flavonoids in diet due to its abundance in foods with the highest antioxidant activity. The antioxidant activity of Myc was studied in cell-free and cell-based systems to evaluate the ROS protection efficiency of Myc. The studies were based on the assessment of reducing power of Myc according to ferric ion reduction and intracellular ROS level measurement by assaying the cellular fluorescence intensity using dichlorodihydrofluorescein (DCF) probe as an indicator for ROS in cells. Moreover, the antitoxic capability of Myc was assessed using MTT method. Data indicated that intracellular ROS are highly toxic and applying low concentration of Myc not only inhibited cellular ROS production but also was accompanying with the protection of cells against the highly toxic and the lethal effects of peroxide compounds. Because of strong correlation between cellular ROS and their cell toxic properties, the higher antioxidant potency of Myc in cell medium resulted in effectively blocking intracellular ROS and protecting cell death. This property is achieved by the help of high polar solubility and cell membrane permeability of Myc.

Myricetin: A Dietary Molecule with Diverse Biological Activities

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson's and Alzheimer's. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound's ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

The dietary flavonoid myricetin regulates iron homeostasis by suppressing hepcidin expression

Hepcidin, a master regulator of iron homeostasis, is a promising target in treatment of iron disorders such as hemochromatosis, anemia of inflammation and iron-deficiency anemia. We previously reported that black soybean seed coat extract could inhibit hepcidin expression. Based on this finding, we performed a screen in cultured cells in order to identify the compounds in black soybeans that inhibit hepcidin expression. We found that the dietary flavonoid myricetin significantly inhibited the expression of hepcidin both in vitro and in vivo. Treating cultured cells with myricetin decreased both HAMP mRNA levels and promoter activity by reducing SMAD1/5/8 phosphorylation. This effect was observed even in the presence of bone morphogenic protein-6 (BMP6) and interleukin-6 (IL-6), two factors that stimulate hepcidin expression. Furthermore, mice that were treated with myricetin (either orally or systemically) had reduced hepatic hepcidin expression, decreased splenic iron levels and increased serum iron levels. Notably, myricetin-treated mice increased red blood cell counts and hemoglobin levels. In addition, pretreating mice with myricetin prevented LPS-induced hypoferremia. We conclude that myricetin potently inhibits hepcidin expression both in vitro and in vivo, and this effect is mediated by altering BMP/SMAD signaling. These experiments highlight the feasibility of identifying and characterizing bioactive phytochemicals to suppress hepcidin expression. These results also suggest that myricetin may represent a novel therapy for treating iron deficiency-related diseases.

Molecular mechanisms underlying anticancer effects of myricetin

Dietary guidelines published in the past two decades have acknowledged the beneficial effects of myricetin, an important and common type of herbal flavonoid, against several human diseases such as inflammation, cardiovascular pathologies, and cancer. An increasing number of studies have shown the beneficial effects of myricetin against different types of cancer by modifying several cancer hallmarks including aberrant cell proliferation, signaling pathways, apoptosis, angiogenesis, and tumor metastasis. Most importantly, myricetin interacts with oncoproteins such as protein kinase B (PKB) (Akt), Fyn, MEK1, and JAK1-STAT3 (Janus kinase-signal transducer and activator of transcription 3), and it attenuates the neoplastic transformation of cancer cells. In addition, myricetin exerts antimitotic effects by targeting the overexpression of cyclin-dependent kinase 1 (CDK1) in liver cancer. Moreover, it also targets the mitochondria and promotes different kinds of cell death in various cancer cells. In the present paper, a critical review of the available literature is presented to identify the molecular targets underlying the anticancer effects of myricetin.

Myricetin inhibits proliferation of cisplatin-resistant cancer cells through a p53-dependent apoptotic pathway

Cisplatin is a commonly used drug for cancer treatment by crosslinking DNA, leading to apoptosis of cancer cells, resistance to cisplatin treatment often occurs, leading to relapse. Therefore, there is a need for the development of more effective treatment strategies that can overcome chemoresistance. Myricetin is a flavonoid from fruits and vegetables, showing anticancer activity in various cancer cells. In this study, we found myricetin exhibited greater cytotoxicity than cisplatin in two cisplatin-resistant ovarian cancer cell lines, OVCAR-3 and A2780/CP70, and it was less cytotoxic to the normal ovarian cell line IOSE-364. Myricetin selectively induced apoptosis in both cisplatin-resistant cancer cell lines, but did not induce apoptosis in the normal ovarian cell line. It induced both Bcl-2 family-dependent intrinsic and DR5 dependent extrinsic apoptosis in OVCAR-3 cells. P53, a multifunctional tumor suppressor, regulated apoptosis in OVCAR-3 cells through a Bcl-2 family protein-dependent pathway. Myricetin did not induce cell cycle arrest in either ovarian cancer cell line. Because of its potency and selectivity against cisplatin-resistant cancer cells, myricetin could potentially be used to overcome cancer chemoresistance against platinum-based therapy.

Hsp70 in cancer: back to the future

Mechanistic studies from cell culture and animal models have revealed critical roles for the heat shock protein Hsp70 in cancer initiation and progression. Surprisingly, many effects of Hsp70 on cancer have not been related to its chaperone activity, but rather to its role(s) in regulating cell signaling. A major factor that directs Hsp70 signaling activity appears to be the co-chaperone Bag3. Here, we review these recent breakthroughs, and how these discoveries drive drug development efforts.