In vitro and in vivo molecular evidence of genistein action in augmenting the efficacy of cisplatin in pancreatic cancer

Anticancer Targets and Signaling Pathways Activated by Britannin and Related Pseudoguaianolide Sesquiterpene Lactones

Sesquiterpene lactones (SLs) are abundant in plants and display a large spectrum of bioactivities. The compound britannin (BRT), found in different Inula species, is a pseudoguaianolide-type SL equipped with a typical and highly reactive α-methylene-γ-lactone moiety. The bioproperties of BRT and related pseudoguaianolide SLs, including helenalin, gaillardin, bigelovin and others, have been reviewed. Marked anticancer activities of BRT have been evidenced in vitro and in vivo with different tumor models. Three main mechanisms are implicated: (i) interference with the NFκB/ROS pathway, a mechanism common to many other SL monomers and dimers; (ii) blockade of the Keap1-Nrf2 pathway, with a covalent binding to a cysteine residue of Keap1 via the reactive α-methylene unit of BRT; (iii) a modulation of the c-Myc/HIF-1α signaling axis leading to a downregulation of the PD-1/PD-L1 immune checkpoint and activation of cytotoxic T lymphocytes. The non-specific reactivity of the α-methylene-γ-lactone moiety with the sulfhydryl groups of proteins is discussed. Options to reduce or abolish this reactivity have been proposed. Emphasis is placed on the capacity of BRT to modulate the tumor microenvironment and the immune-modulatory action of the natural product. The present review recapitulates the anticancer effects of BRT, some central concerns with SLs and discusses the implication of the PD1/PD-L1 checkpoint in its antitumor action.

Modulation of inflammation by phytochemicals to enhance efficacy and reduce toxicity of cancer chemotherapy

Treatment of cancer with chemotherapeutic drugs is associated with numerous adverse effects as well as the eventual development of resistance to chemotherapy. There is a great need for complementary therapies such as botanicals and nutritional supplements with little or no side effects that prevent resistance to chemotherapy and reduce its adverse effects. Inflammation plays a major role in the development of chemoresistance and the adverse effects of chemotherapy. Phytochemicals have well-established anti-inflammatory effects; thus, they could be used as complementary therapies along with chemotherapy to increase its efficacy and reduce its toxicity. Botanical compounds inhibit the NF-κB signaling pathway, which plays an important role in the generation of inflammation, chemotherapy resistance, and modulation of cell survival and apoptosis. Botanicals have previously been studied extensively for their cancer chemopreventive activities and are generally considered safe for human consumption. The present review focuses on the modulation of inflammation by phytochemicals and their role in increasing the efficacy and reducing the toxicity of cancer chemotherapy.

Genistein enhances the effects of L-asparaginase on inducing cell apoptosis in human leukemia cancer HL-60 cells

Genistein (GEN) has been shown to induce apoptotic cell death in various human cancer cells. L-asparaginase (Asp), a clinical drug for leukemia, has been shown to induce cell apoptosis in leukemia cells. No available information concerning GEN combined with Asp increased the cell apoptosis compared to GEN or Asp treatment alone. The objective of this study is to evaluate the anti-leukemia activity of GEN combined with Asp on human leukemia HL-60 cells in vitro. The cell viability, the distribution of cell cycle, apoptotic cell death, and the level of ΔΨ_m were examined by flow cytometric assay. The expressions of apoptosis-associated proteins were measured by western blotting. GEN combined with Asp revealed a more significant decrease in total viable cells and induced a higher percentage of G2/M phase arrest, DNA damage, and cell apoptosis than that of GEN or Asp treatment only in HL-60 cells. Furthermore, the combined treatments (GEN and Asp) showed a higher decrease in the level of ΔΨ_m than that of GEN or Asp treatment only. These results indicated that GEN combined with Asp induced mitochondria dysfunction by disrupting the mitochondrial membrane potential. The results from western blotting demonstrated that the treatment of GEN combined with Asp showed a higher increase in the levels of Bax and Bak (pro-apoptotic proteins) and an active form of caspase-3 and a higher decrease in Bcl-2 (anti-apoptotic protein) than that of GEN or Asp treatment alone. GEN significantly enhances the efficiency of Asp on cytotoxic effects (the induction of apoptosis) in HL-60 cells.

Plant Polyphenolic Compounds Potentiates Therapeutic Efficiency of Anticancer Chemotherapeutic Drugs: A Review

BACKGROUND

Scientific research continues to develop more efficacious drugs to treat and cure cancer, the dreadful disease threatening the human race. Chemotherapy is an essential means in cancer therapy, however, plant drugs having pharmacological safety, can be used alone or as additions to current chemotherapeutic agents to enhance therapeutic efficacy and minimize chemotherapyinduced adverse effects.

OBJECTIVE

A combination therapy where the synergistic effect on multiple targets is possible has gained significance because a one-drug one-target approach fails to yield the desired therapeutic effect. Therefore, a detailed description of important plant polyphenolic compounds with anticancer activity and their role in potentiating chemotherapeutic efficiency of existing anticancer drugs is provided in this review. Systematically screening combinations of active pharmaceutical ingredients for potential synergy with plant compounds may be especially valuable in cancer therapy.

METHODS

We extensively have gone through reviews and research articles available in the literature. We made use of databases such as Google Scholar, Research Gate, PubMed, Science Direct, etc. The following keywords were used in our literature search: "Chemotherapy, drug development, cancer drugs, plant-derived polyphenolics, synergistic studies, combination therapy, diagnosis and genetics."

CONCLUSION

Systematic research studies on screening combinations of plant phytochemicals with potential chemotherapeutic pharmaceuticals shed light on their synergistic effects, mechanisms of actions paving the way to develop more efficient anticancer therapeutics to treat and cure the cancer menace, to nullify chemotherapy-induced adverse effects and our review substantially contributes in this direction.

MicroRNA let-7d targets thrombospondin-1 and inhibits the activation of human pancreatic stellate cells

OBJECTIVES

The microRNA (miRNA) let-7d is linked to the formation of pancreatic cancer-related fibrosis. In this study, the mechanism by which let-7d regulates the activation of the human pancreatic stellate cell (hPSC) was evaluated.

METHODS

The transient transfection of a let-7d mimic in the hPSCs was performed, and the altered thrombospondin 1 (THBS1) expression was confirmed by western blotting and real-time qPCR. Targeting of the 3'-untranslated region (UTR) of THBS1 by let-7d was investigated by the luciferase assays. After hPSC transfection using THBS1 siRNA, the fibrosis markers (α-SMA and collagen 1A1) were evaluated by western blotting and real-time qPCR. The correlation between tumor fibrosis and let-7d or THBS1 was estimated using the data from The Cancer Genome Atlas project. Finally, the effects of genistein on the hPSCs were evaluated.

RESULTS

We found that a let-7d mimic inhibits THBS1 expression by targeting its 3'-UTR. THBS1 inhibition by siRNA inhibited hPSC activation. An in silico analysis revealed that let-7d and THBS1 expression are negatively correlated. Additionally, let-7d was negatively correlated with the stromal score, while THBS1 was positively correlated with this score. Genistein substantially induced let-7d and decreased the expression of fibrosis marker along with the inhibition of THBS1.

CONCLUSIONS

Let-7d inhibited hPSC activation by targeting THBS1. Genistein induced the expression of let-7d and might modulate pancreatic fibrosis.

Flavonoids in Cancer and Apoptosis

Cancer is the second leading cause of death globally. Although, there are many different approaches to cancer treatment, they are often painful due to adverse side effects and are sometimes ineffective due to increasing resistance to classical anti-cancer drugs or radiation therapy. Targeting delayed/inhibited apoptosis is a major approach in cancer treatment and a highly active area of research. Plant derived natural compounds are of major interest due to their high bioavailability, safety, minimal side effects and, most importantly, cost effectiveness. Flavonoids have gained importance as anti-cancer agents and have shown great potential as cytotoxic anti-cancer agents promoting apoptosis in cancer cells. In this review, a summary of flavonoids and their effectiveness in cancer treatment targeting apoptosis has been discussed.

Synergistic Action of 1,2-Epoxy-3 (3- (3,4-dimethoxyphenyl)- 4H-1-benzopiyran-4-on) Propane with Doxorubicin and Cisplatin through Increasing of p53, TIMP-3, and MicroRNA-34a in Cervical Cancer Cell Line (HeLa)

Objective: Cervical cancer is the second most common cancer among women worldwide, with a high mortality rate especially in developing countries. Insufficient treatment for cervical cancer, multiple side effects, and high drug prices encourage researchers to look for effective and selective cancer drugs with appropriate molecular targets. This study explored the cytotoxicity of (1,2-epoxy-3(3-(3,4-dimethoxyphenyl)-4H-1-benzopyran-4-on) propane (EPI) synthesized from clove leaves oil on HeLa cells, its combination with doxorubicin (DOX) and cisplatin (CIS), and also their influence on p53, TIMP-3, and miR-34a as therapeutic targets. Materials and Methods: This research was an experimental in vitro study on cervical cancer uteri culture. The cytotoxicity was analyzed by MTT assay. The drug combination synergisms were indicated by the combination index (CI) (using CompuSyn 1.4). HeLa cells in 32 wells were divided into eight groups as negative control, which were given EPI ½IC50, EPI IC50, EPI 2IC50, DOX IC50, combination of EPI+DOX, CIS, and the combination of EPI+CIS. The p53 and TIMP-3 concentrations were measured using ELISA, and expressions of miR-34a with qRT-PCR. One-way ANOVA and post hoc Tukey tests were performed to determine the mean difference of all variables between the study groups. Results: IC50 for EPI was 33.24 (±3.01) μg/ml, while DOX and CIS were 4.8 μg/ml (±0.1), and 23.34 μg/ml (±3.01), respectively, while CI values for EPI-DOX were <0.1 and for EPI-CIS <0.9. Expression of p53 in group 6 (1.67±0.31) μg/ml and 8 (1.18±0.18) μg/ml, TIMP-3 6 (3.81±0.49) μg/ml and 8 (2.93±0.42) μg/ml were significantly higher compared to the control group (p<0.05). All treatment groups showed significantly increased miR-34a expressions compared to the control group (p<0.05). Conclusion: The combinations showed a very strong synergism and a moderate slight synergism for EPI-DOX and EPI-CIS. Both combinations were able to increase the expressions of p53, TIMP-3 proteins, and MiR-34a in the HeLa cells.

Dietary Soy Isoflavone: A Mechanistic Insight

Soy, a major component of the diet for centuries contains the largest concentration of isoflavones, a class of phytoestrogens. A variety of health benefits are associated with the consumption of soy primarily because of the isoflavones genistein, daidzein, and glycitein with a potential protective effect against a number of chronic diseases. Owing to the pharmaceutical and nutraceutical properties allied with isoflavonoids and their use in functional foods, there is a growing interest in these compounds. This review throws light on the chemistry, and significant pharmacological and biopharmaceutical aspects of soy isoflavones. This article critically describes the mechanisms of action, infers conclusions and shows opportunity for future research.

A phase I dose escalation trial of AXP107-11, a novel multi-component crystalline form of genistein, in combination with gemcitabine in chemotherapy-naive patients with unresectable pancreatic cancer

BACKGROUND

AXP107-11 is a novel, multi-component crystalline form of the naturally occurring compound genistein. AXP107-11 has improved physiochemical properties and oral bioavailability compared to the natural form of genistein, and it is possible that combining AXP107-11 with chemotherapy may increase the effect and reduce chemoresistance. The purpose of this dose escalation phase Ib study was to assess the safety, maximum tolerated dose (MTD) and pharmacokinetics (PK) of AXP107-11 in combination with gemcitabine in treatment-naïve patients with inoperable pancreatic carcinoma.

PATIENTS AND METHODS

AXP107-11 was given orally in escalating doses (400 mg-1600 mg daily) in combination with standard gemcitabine treatment (1000 mg/m(2)/week) for the first seven of eight weeks and thereafter for a maximum of four × four-week treatment cycles. PK, safety, MTD and efficacy of AXP107-11 in combination with gemcitabine were evaluated.

RESULTS

Sixteen patients were enrolled and received AXP107-11. The maximum concentration in serum of unconjugated (free) genistein was 1 μM. Neither dose-limiting toxicities (DLTs) nor signs of hematological or non-hematological toxicities related to AXP107-11 were observed over a period ranging from 0.7 to 13.2 months. The median overall survival time was 4.9 months (range 1.5-19.5 months). Seven patients (44%) survived longer than six months and 19% were alive at the one-year follow-up.

CONCLUSION

Treatment of pancreatic cancer patients with AXP107-11 in combination with gemcitabine resulted in a favorable PK-profile with high serum levels without signs of either hematological or non-hematological toxicity. Accordingly, we suggest further studies with AXP107-11 in pancreatic cancer patients.

Piperlongumine Suppresses Growth and Sensitizes Pancreatic Tumors to Gemcitabine in a Xenograft Mouse Model by Modulating the NF-kappa B Pathway

Pancreatic cancer is an aggressive malignancy, which generally respond poorly to chemotherapy. Hence, novel agents that are safe and effective are highly needed. The aim of this study was to investigate whether piperlongumine, a natural product isolated from the fruit of the pepper Piper longum, has any efficacy against human pancreatic cancer when used either alone or in combination with gemcitabine in vitro and in a xenograft mouse model. In vitro, piperlongumine inhibited the proliferation of pancreatic cancer cell lines, potentiated the apoptotic effects of gemcitabine, inhibited the constitutive and inducible activation of NF-κB, and suppressed the NF-κB-regulated expression of c-Myc, cyclin D1, Bcl-2, Bcl-xL, Survivin, XIAP, VEGF, and matrix metalloproteinase-9 (MMP-9). Furthermore, in an in vivo xenograft model, we found piperlongumine alone significantly suppressed tumor growth and enhanced the antitumor properties of gemcitabine. These results were consistent with the downregulation of NF-κB activity and its target genes, decreased proliferation (PCNA and Ki-67), decreased microvessel density (CD31), and increased apoptosis (TUNEL) in tumor remnants. Collectively, our results suggest that piperlongumine alone exhibits significant antitumor effects against human pancreatic cancer and it further enhances the therapeutic effects of gemcitabine, possibly through the modulation of NF-κB- and NF-κB-regulated gene products.

The mTOR signalling pathway in cancer and the potential mTOR inhibitory activities of natural phytochemicals

The mammalian target of rapamycin (mTOR) kinase plays an important role in regulating cell growth and cell cycle progression in response to cellular signals. It is a key regulator of cell proliferation and many upstream activators and downstream effectors of mTOR are known to be deregulated in various types of cancers. Since the mTOR signalling pathway is commonly activated in human cancers, many researchers are actively developing inhibitors that target key components in the pathway and some of these drugs are already on the market. Numerous preclinical investigations have also suggested that some herbs and natural phytochemicals, such as curcumin, resveratrol, timosaponin III, gallic acid, diosgenin, pomegranate, epigallocatechin gallate (EGCC), genistein and 3,3'-diindolylmethane inhibit the mTOR pathway either directly or indirectly. Some of these natural compounds are also in the clinical trial stage. In this review, the potential anti-cancer and chemopreventive activities and the current status of clinical trials of these phytochemicals are discussed.

In vitro and in vivo antitumoral effects of combinations of polyphenols, or polyphenols and anticancer drugs: perspectives on cancer treatment

Carcinogenesis is a multistep process triggered by genetic alterations that activate different signal transduction pathways and cause the progressive transformation of a normal cell into a cancer cell. Polyphenols, compounds ubiquitously expressed in plants, have anti-inflammatory, antimicrobial, antiviral, anticancer, and immunomodulatory properties, all of which are beneficial to human health. Due to their ability to modulate the activity of multiple targets involved in carcinogenesis through direct interaction or modulation of gene expression, polyphenols can be employed to inhibit the growth of cancer cells. However, the main problem related to the use of polyphenols as anticancer agents is their poor bioavailability, which might hinder the in vivo effects of the single compound. In fact, polyphenols have a poor absorption and biodistribution, but also a fast metabolism and excretion in the human body. The poor bioavailability of a polyphenol will affect the effective dose delivered to cancer cells. One way to counteract this drawback could be combination treatment with different polyphenols or with polyphenols and other anti-cancer drugs, which can lead to more effective antitumor effects than treatment using only one of the compounds. This report reviews current knowledge on the anticancer effects of combinations of polyphenols or polyphenols and anticancer drugs, with a focus on their ability to modulate multiple signaling transduction pathways involved in cancer.

Cytotoxicity of gemcitabine enhanced by polyphenolics from Aronia melanocarpa in pancreatic cancer cell line AsPC-1

AIMS

Extending work with brain tumours, the hypothesis that micronutrients may usefully augment anticancer regimens, chokeberry (Aronia melanocarpa) extract was tested to establish whether it has pro-apoptotic effects in AsPC-1, an established human pancreatic cell line, and whether it potentiates cytotoxicity in combination with gemcitabine. Pancreatic cancer was chosen as a target, as its prognosis remains dismal despite advances in therapy.

METHODS

An MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay was used to assess the growth of the single pancreatic cancer cell line AsPC-1, alone and in comparison or combination with gemcitabine. This was backed up by flow cytometric DRAQ7 cell viability analysis. TUNEL assays were also carried out to investigate pro-apoptotic properties as responsible for the effects of chokeberry extract.

RESULTS

Chokeberry extract alone and its IC75 value (1 µg/mL) in combination with gemcitabine were used to assess the growth of the AsPC-1 cell line. Gemcitabine in combination with chokeberry extract was more effective than gemcitabine alone. TUNEL assays showed apoptosis to be a mechanism occurring at 1 µg/mL concentration of chokeberry, with apoptotic bodies detected by both colourimetric and fluorometric methods.

CONCLUSIONS

The implication of this study, using single cancer cell line, is that chemotherapy (at least with gemcitabine) might be usefully augmented with the use of micronutrients such as chokeberry extract.

Use of herbal medicines and natural products: an alternative approach to overcoming the apoptotic resistance of pancreatic cancer

Pancreatic cancer has a poor prognosis with a 5-year survival rate of <5%. It does not respond well to either chemotherapy or radiotherapy, due partly to apoptotic resistance (AR) of the cancer cells. AR has been attributed to certain genetic abnormalities or defects in apoptotic signaling pathways. In pancreatic cancer, significant mutations of K-ras and p53, constitutive activation of NFκB, over-expression of heat shock proteins (Hsp90, Hsp70), histone deacetylase (HDACs) and the activities of other proteins (COX-2, Nrf2 and bcl-2 family members) are closely linked with resistance to apoptosis and invasion. AR has also been associated with aberrant signaling of MAPK, PI3K-AKT, JAK/STAT, SHH, Notch, and Wnt/β-catenin pathways. Strategies targeting these signaling molecules and pathways provide an alternative for overcoming AR in pancreatic cancer. The use of herbal medicines or natural products (HM/NPs) alone or in combination with conventional anti-cancer agents has been shown to produce beneficial effects through actions upon multiple molecular pathways involved in AR. The current standard first-line chemotherapeutic agents for pancreatic cancer are gemcitabine (Gem) or Gem-containing combinations; however, the efficacy is dissatisfied and this limitation is largely attributed to AR. Meanwhile, emerging data have pointed to a combination of HM/NPs that may augment the sensitivity of pancreatic cancer cells to Gem. Greater understanding of how these compounds affect the molecular mechanisms of apoptosis may propel development of HM/NPs as anti-cancer agents and/or adjuvant therapies forward. In this review, we give a critical appraisal of the use of HM/NPs alone and in combination with anti-cancer drugs. We also discuss the potential regulatory mechanisms whereby AR is involved in these protective pathways.

The effects of bioactive compounds from plant foods on mitochondrial function: a focus on apoptotic mechanisms

Mitochondria are essential organelles for cellular integrity and functionality maintenance and their imparement is implicated in the development of a wide range of diseases, including metabolic, cardiovascular, degenerative and hyperproliferative pathologies. The identification of different compounds able to interact with mitochondria for therapeutic purposes is currently becoming of primary importance. Indeed, it is well known that foods, particularly those of vegetable origin, present several constituents with beneficial effects on health. This review summarizes and updates the most recent findings concerning the mechanisms through which different dietary compounds from plant foods affect mitochondria functionality in healthy and pathological in vitro and in vivo models, paying particular attention to the pathways involved in mitochondrial biogenesis and apoptosis.

Fruit-derived phenolic compounds and pancreatic cancer: perspectives from Australian native fruits

ETHNOPHARMACOLOGICAL RELEVANCE

Pancreatic cancer is a devastating cancer that presents late, is rapidly progressive and has current therapeutics with only limited efficacy. Bioactive compounds are ubiquitously present in fruits and numerous studies in vitro are addressing the activity of these compounds against pancreatic cancer, thus studies of specific bioactive compounds could lead to new anti-pancreatic cancer strategies. Australian native fruits have been used as foods and medicines by Australian Aboriginals for thousands of years, and preliminary studies have found these fruits to contain rich and diversified bioactive components with high antioxidant activity. Thus, Australian native fruits may possess key components for preventing or delaying the onset of tumorigenesis, or for the treatment of existing cancers, including pancreatic cancer.

MATERIALS AND METHODS

Numerous databases including PubMed, SciFinder, Web of Knowledge, Scopus, and Sciencedirect were analysed for correlations between bioactive components from fruits and pancreatic cancer, as well as studies concerning Australian native fruits.

RESULTS

In this review, we comprehensively highlight the proposed mechanisms of action of fruit bioactives as anti-cancer agents, update the potential anti-pancreatic cancer activity of various major classes of bioactive compounds derived from fruits, and discuss the existence of bioactive compounds identified from a selection Australian native fruits for future studies.

CONCLUSION

Bioactive compounds derived from fruits possess the potential for the discovery of new anti-pancreatic cancer strategies. Further, Australian native fruits are rich in polyphenols including some flora that contain unique phenolic compounds, thereby warranting further investigations into their anti-cancer properties.

Additivity, antagonism, and synergy in arsenic trioxide-induced growth inhibition of C6 glioma cells: effects of genistein, quercetin and buthionine-sulfoximine

Arsenic trioxide (ATO) induces clinical remission in acute promyelocytic leukemia and growth inhibition in various cancer cell lines in vitro. Recently, genistein and quercetin were reported to potentiate ATO-provoked apoptosis in leukemia and hepatocellular carcinoma cells. Genistein acted via enhanced ROS generation and quercetin via glutathione depletion. Searching for potential strategies for the treatment of malignant gliomas in this study the capacity of these flavonoids to sensitize rat C6 astroglioma cells for the cytotoxic action of ATO was investigated. ATO inhibited cell growth in a concentration- and time-dependent manner. This effect was accompanied neither by enhanced radical generation nor lipid peroxidation and was not attributed to apoptosis. ATO treatment concentration-dependently increased glutathione levels. Genistein enhanced radical generation. Combined with ATO it inhibited cell growth additively. Additivity was also obtained after cotreatment with ATO and H2O2. Quercetin acted antagonistically on ATO-induced growth inhibition. Quercetin increased glutathione levels. In contrast, buthionine-sulfoximine (BSO) depleted cellular glutathione and acted synergistically with ATO. In conclusion, in C6 cells neither genistein nor quercetin are suited as sensitizing agent, in contrast to BSO. Depletion of cellular glutathione content rather than an increase of ROS generation plays a central role in the enhancement of ATO-toxicity in C6 cells.

Antitumor activity of gemcitabine can be potentiated in pancreatic cancer through modulation of TLR4/NF-κB signaling by 6-shogaol

Advanced pancreatic cancer still has a poor prognosis, even with the approval of several drugs, such as gemcitabine. Therefore, developing effective and safe antitumor agents is urgently needed. 6-Shogaol, a phenol extracted from ginger, has been linked to suppression of proliferation and survival of cancer with different mechanisms. In the present study, we investigated whether 6-shogaol could suppress pancreatic cancer progress and potentiate pancreatic cancer to gemcitabine treatment in vitro and in vivo. We found that 6-shogaol prevented the activation of toll like receptor 4 (TLR4)/NF-κB signaling. The modulation of NF-κB signaling by 6-shogaol was ascertained by electrophoretic mobility shift assay and western blot analysis. The suppression of NF-κB signaling and key cell survival regulators including COX-2, cyclinD1, survivin, cIAP-1, XIAP, Bcl-2, and MMP-9 brought the anti-proliferation effects in pancreatic cancer cells and sensitized them to gemcitabine treatment. Furthermore, in a pancreatic cancer xenograft model, we found a decreased proliferation index (Ki-67) and increased apoptosis by TUNEL staining in 6-shogaol treated tumors. It was also shown that 6-shogaol combined with gemcitabine treatment was more effective than drug alone, consistent with the downregulation of NF-κB activity along with its target genes COX-2, cyclinD1, survivin, cIAP-1, and XIAP. Overall, our results suggest that 6-shogaol can inhibit the growth of human pancreatic tumors and sensitize them to gemcitabine by suppressing of TLR4/NF-κB-mediated inflammatory pathways linked to tumorigenesis.

Cisplatin-induced non-apoptotic death of pancreatic cancer cells requires mitochondrial cyclophilin-D-p53 signaling

The pancreatic cancer remains a fatal disease for the majority of patients. Cisplatin has displayed significant cytotoxic effects against the pancreatic cancer cells, however the underlying mechanisms remain inconclusive. Here, we found that cisplatin mainly induced non-apoptotic death of the pancreatic cancer cells (AsPC-1 and Capan-2), which was associated with a significant p53 activation (phosphorylation and accumulation). Further, activated p53 was found to translocate to mitochondria where it formed a complex with cyclophilin D (Cyp-D). We provided evidences to support that mitochondrial Cyp-D/p53 complexation might be critical for cisplatin-induced non-apoptotic death of pancreatic cancer cells. Inhibition of Cyp-D by its inhibitor cyclosporine A (CsA), or by shRNA-mediated knockdown suppressed cisplatin-induced pancreatic cancer cell death. Both CsA and Cyp-D knockdown also disrupted the Cyp-D/p53 complex formation in mitochondria. Meanwhile, the pancreatic cancer cells with p53 knockdown were resistant to cisplatin. On the other hand, HEK-293 over-expressing Cyp-D were hyper-sensitive to cisplatin. Interestingly, camptothecin (CMT)-induced pancreatic cancer cell apoptotic death was not affected CsA or Cyp-D knockdown. Together, these data suggested that cisplatin-induced non-apoptotic death requires mitochondria Cyp-D-p53 signaling in pancreatic cancer cells.

Pleiotropic effects of genistein in metabolic, inflammatory, and malignant diseases

Genistein is a soy-derived biologically active isoflavone that exhibits diverse health-promoting effects. An increasing body of evidence shows that genistein influences lipid homeostasis and insulin resistance, counteracts inflammatory cytokines, and possesses antidiabetic properties. Genistein also impedes cancer progression by promoting apoptosis, inducing cell cycle arrest, modulating intracellular signaling pathways, and inhibiting angiogenesis and metastasis of neoplastic cells. This review summarizes the pleiotropic functions of genistein in common health disorders such as metabolic syndrome, chronic inflammatory diseases, and cancer. In the current era of uncontrolled health expenditure, a focus on the clinical development of nutritional agents with the capacity to prevent a variety of common health disorders is needed. As a micronutrient that exerts multifaceted effects ranging from antidiabetic to anticarcinogenic functions, genistein should be clinically developed further for use in the prevention and treatment of a variety of health disorders.

Phytochemicals as chemosensitizers: from molecular mechanism to clinical significance

This review provides an overview of the clinical relevance of chemosensitization, giving special reference to the phenolic phytochemicals, curcumin, genistein, epigallocatechin gallate, quercetin, emodin, and resveratrol, which are potential candidates due to their ability to regulate multiple survival pathways without inducing toxicity. We also give a brief summary of all the clinical trials related to the important phytochemicals that emerge as chemosensitizers. The mode of action of these phytochemicals in regulating the key players of the death receptor pathway and multidrug resistance proteins is also abridged. Rigorous efforts in identifying novel chemosensitizers and unraveling their molecular mechanism have resulted in some of the promising candidates such as curcumin, genistein, and polyphenon E, which have gone into clinical trials. Even though considerable research has been conducted in identifying the salient molecular players either contributing to drug efflux or inhibiting DNA repair and apoptosis, both of which ultimately lead to the development of chemoresistance, the interdependence of the molecular pathways leading to chemoresistance is still the impeding factor in the success of chemotherapy. Even though clinical trials are going on to evaluate the chemosensitizing efficacy of phytochemicals such as curcumin, genistein, and polyphenon E, recent results indicate that more intense study is required to confirm their clinical efficacy. Current reports also warrant intense investigation about the use of more phytochemicals such as quercetin, emodin, and resveratrol as chemosensitizers, as all of them have been shown to modulate one or more of the key regulators of chemoresistance.

Sensitization of Cervical Cancer Cells to Cisplatin by Genistein: The Role of NFκB and Akt/mTOR Signaling Pathways

Cervical cancer is among the top causes of death from cancer in women. Cisplatin-based chemotherapy has been shown to improve survival; however, cisplatin treatment is associated with toxicity to healthy cells. Genistein has been used as an adjunct to chemotherapy to enhance the activity of chemotherapeutic agents without causing increased toxicity. The present study was designed to investigate the effect of genistein (25 μM) on antitumor activity of cisplatin (250 nM) on HeLa cervical cancer cells. We have examined the alterations in expression of NF-κB, p-mTOR, p-p70S6K1, p-4E-BP1, and p-Akt protein levels in response to treatment. The combination of 25 μM genistein with 250 nM cisplatin resulted in significantly greater growth inhibition (P < 0.01). Genistein enhanced the antitumor activity of cisplatin and reduced the expression of NF-κB, p-mTOR, p-p70S6K1, p-4E-BP1, and p-Akt. The results in the present study suggest that genistein could enhance the activity of cisplatin via inhibition of NF-κB and Akt/mTOR pathways. Genistein is a promising nontoxic nutritional agent that may enhance treatment outcome in cervical cancer patients when given concomitantly with cisplatin. Clinical trials of genistein and cisplatin combination are warranted to test this hypothesis.

RNAi knockdown of the Akt1 gene increases the chemosensitivity of gastric cancer cells to cisplatin both in vitro and in vivo

AIM

To examine the in vitro and in vivo effects of a combined treatment of cis-d iamminedichloroplatinum(II) (cisplatin) with downregulation of Akt1 expression in gastric cancer cells.

MATERIALS AND METHODS

Lentivirus-mediated RNA interference (RNAi) was used to silence the Akt1 gene. pGCSIL-Akt1 small hairpin RNA (shRNA) was stably transfected into gastric cancer cells (SGC7901 and BGC823). Next, the effects of Akt1 downregulation on the growth and apoptosis of SGC7901 (BGC823) cells in the presence or absence of cisplatin were investigated by real-time polymerase chain reaction (RT-PCR), Western blot analysis, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-d-iphenyltetrazolium bromide) assay, Hoechst assay, flow cytometric analysis of annexin V-FITC/PI staining, and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling). Finally, the effects of downregulation of Akt1 expression on the sensitivity of SGC7901 cells in a tumor xenograft model of cisplatin were also determined.

RESULT

Akt1 silencing reduced gastric cancer proliferation and increased cell apoptosis both in vitro and in vivo. The chemosensitivity of SGC7901 (BGC823) cells to cisplatin increased significantly following the downregulation of Akt1 expression, which might be associated with the inactivation of the PI3K/Akt1 signaling pathway, followed by the induced expression of the pro-apoptotic protein Bax and a concomitant decrease of Bcl-2 expression.

CONCLUSION

This study confirmed that downregulation of Akt1 reduced chemotherapy tolerance of gastric cancer cells to cisplatin treatment. Thus, Akt1 silencing and cisplatin appear to be an effective combination treatment strategy for gastric cancer.

Enhanced antitumor efficacy of gemcitabine by evodiamine on pancreatic cancer via regulating PI3K/Akt pathway

Evodiamine has therapeutic potential against cancers. This study was designed to investigate whether combination therapy with gemcitabine and evodiamine enhanced antitumor efficacy in pancreatic cancer. In vitro application of the combination therapy triggered significantly higher frequency of pancreatic cancer cells apoptosis, inhibited the activities of PI3K, Akt, PKA, mTOR and PTEN, and decreased the activation of NF-κB and expression of NF-κB-regulated products. In vivo application of the combination therapy induced significant enhancement of tumor cell apoptosis, reductions in tumor volume, and inhibited activation of mTOR and PTEN. In conclusion, evodiamine can augment the therapeutic effect of gemcitabine in pancreatic cancer through direct or indirect negative regulation of the PI3K/Akt pathway.

Down-regulation of Notch-1 is associated with Akt and FoxM1 in inducing cell growth inhibition and apoptosis in prostate cancer cells

Although many studies have been done to uncover the mechanisms by which down-regulation of Notch-1 exerts its anti-tumor activity against a variety of human malignancies, the precise molecular mechanisms remain unclear. In the present study, we investigated the cellular consequence of Notch-1 down-regulation and also assessed the molecular consequence of Notch-1-mediated alterations of its downstream targets on cell viability and apoptosis in prostate cancer (PCa) cells. We found that the down-regulation of Notch-1 led to the inhibition of cell growth and induction of apoptosis, which was mechanistically linked with down-regulation of Akt and FoxM1, suggesting for the first time that Akt and FoxM1 are downstream targets of Notch-1 signaling. Moreover, we found that a "natural agent" (genistein) originally discovered from soybean could cause significant reduction in cell viability and induced apoptosis of PCa cells, which was consistent with down-regulation of Notch-1, Akt, and FoxM1. These results suggest that down-regulation of Notch-1 by novel agents could become a newer approach for the prevention of tumor progression and/or treatment, which is likely to be mediated via inactivation of Akt and FoxM1 signaling pathways in PCa.

Risks and benefits of dietary isoflavones for cancer

A high intake of fruits and vegetables is associated with a lower risk of cancer. In this context, considerable attention is paid to Asian populations who consume high amounts of soy and soy-derived isoflavones, and have a lower risk for several cancer types such as breast and prostate cancers than populations in Western countries. Hence, interest focuses on soyfoods, soy products, and soy ingredients such as isoflavones with regard to their possible beneficial effects that were observed in numerous experiments and studies. The outcomes of the studies are not always conclusive, are often contradictory depending on the experimental conditions, and are, therefore, difficult to interpret. Isoflavone research revealed not only beneficial but also adverse effects, for instance, on the reproductive system. This is also the case with tumor-promoting effects on, for example, breast tissue. Isoflavone extracts and supplements are often used for the treatment of menopausal symptoms and for the prevention of age-associated conditions such as cardiovascular diseases and osteoporosis in postmenopausal women. In relation to this, questions about the effectiveness and safety of isoflavones have to be clarified. Moreover, there are concerns about the maternal consumption of isoflavones due to the development of leukemia in infants. In contrast, men may benefit from the intake of isoflavones with regard to reducing the risk of prostate cancer. Therefore, this review examines the risks but also the benefits of isoflavones with regard to various kinds of cancer, which can be derived from animal and human studies as well as from in vitro experiments.

Review on molecular and therapeutic potential of thymoquinone in cancer

Thymoquinone (TQ) is the predominant bioactive constituent present in black seed oil (Nigella sativa) and has been tested for its efficacy against cancer. Here, we summarize the literature about TQ's molecular mechanism of action and its ability to induce apoptosis and inhibit tumor growth in preclinical models. TQ has anti-inflammatory effects, and it inhibits tumor cell proliferation through modulation of apoptosis signaling, inhibition of angiogenesis, and cell cycle arrest. Chemosensitization by TQ is mostly limited to in vitro studies, and it has potential in therapeutic strategy for cancer. The results favor efficacy and enhancement of therapeutic benefit against tumor cells resistant to therapy based on cellular targets that are molecular determinants for cancer cell survival and progression. There have been attempts to synthesize novel analogs of TQ directed toward superior effects in killing tumor cells with more enhanced chemosensitizing potential than parent TQ compound. Based on published reports, we believe that further in-depth studies are warranted including investigation of its bioavailability and Phase I toxicity profiling in human subjects. The results from such studies will be instrumental in advancing this field in support of initiating clinical trials for testing the effects of this ancient agent in cancer therapy.

Effects of an Indolocarbazole-Derived CDK4 Inhibitor on Breast Cancer Cells

Introduction: Cyclin D1 (D1) binds to cyclin-dependent kinases (CDK) 4 or 6 to form a holoenzyme that phosphorylates the Rb protein to promote cell cycle progression from G1 to S phase. Therefore, targeting CDK4/6 may be a good strategy for chemotherapy of cancer. We performed a proof-of-principle study to determine the effect of Naphtho [2, 1-α] pyrrolo [3, 4-c] carbazole-5, 7 (6H, 12H)-dione (NPCD), a novel CDK4 inhibitor, on breast cancer cell lines.

Methods: NPCD was synthesized and purified to over 99% purity verified by HPLC. MCF7, MB231, MCF15, T47D and GI101Ap human breast cancer cells were analyzed for the efficacy of NPCD with MTT and clonogenic assays, with FACS and staining for ethidium bromide and acridine orange for cell death and cell cycle profile. Western blot, reverse transcription and PCR were used for studies of gene expression, and co-immunoprecipitation for protein-complex formation.

Results: MTT assay showed that NPCD caused growth arrest and apoptosis of MCF7, MDA-MB231, T47D, MCF15 and GI101Ap cells with an IC50 ranging between 3 to 8 µM given as a single dose. The growth arrest persisted for many days after cessation of the treatment, as shown in a clonogenic assay. NPCD could induce or reduce the D1 and CDK4 protein levels, depending on the cell line, but this effect was not correlated with its efficacy. Phosphorylation of D1 at Thr286 was decreased but it unexpectedly did not correlate with the change in D1 level in the cell lines studied. Phosphorylation of the Rb protein was decreased as expected whereas the p27kip1 protein level was decreased unexpectedly. Protein levels of p21cip1, CDK2 and cyclin E were also decreased in some, but not all, of the cell lines, whereas the mRNA levels of D1, CDK4, cyclin E, CDK2, p27kip1 and p21cip1 were increased in different cell lines.

Conclusions: NPCD can cause long-lasting growth arrest and cell death of breast cancer cell lines at an IC50 of 3-8 µM. Decreased phosphorylation of Rb by D1-CDK4/6 and decreased p27kip1 protein level may be part of the underlying mechanism.

Dietary factors and pancreatic cancer: the role of food bioactive compounds

Pancreatic cancer is the fourth leading cause of cancer mortality among both men and women in the United States with a 5-year survival rate of only 4%. Several dietary factors may influence the risk of developing pancreatic cancer and its recurrence. Some of these factors may offer innovative therapies for prevention of this disease. The goal of this review is to provide an overview of pancreatic cancer, as well as current knowledge on the epidemiological, in vitro, in vivo, and clinical studies conducted about this disease using various dietary agents. The main focus is on food-based approaches for preventing this disease particularly, citrus fruits, and foods containing flavonoids, curcumin, folate and vitamin D.

Restoring sensitivity to oxaliplatin by a novel approach in gemcitabine-resistant pancreatic cancer cells in vitro and in vivo

Oxaliplatin (OxP) has been used in combination therapy with gemcitabine for the treatment of pancreatic cancer (PC), but the beneficial effect was marginal, which is believed to be due to de novo and acquired drug resistance of PC. Here, we report our in vitro and in vivo preclinical evidence in support of chemosensitization of drug-resistant cells by a nontoxic chemopreventive agent (genistein). Genistein pretreatment together with low concentration of OxP showed significant reduction in cell viability and colony formation concomitant with increased apoptosis (p < 0.01), which was highly synergistic. Drug resistance of PC is allegedly linked with both constitutive and OxP-induced activation of NF-κB, and we found that inactivation of (nuclear factor kappa B) NF-κB by genistein before treatment of cells with OxP was required for cell killing, which was consistent with the downregulation of NF-κB and its downstream antiapoptotic genes (Bcl-2, XIAPs and survivin). Most importantly, our in vivo experiments using orthotopic mouse model showed significant reduction in tumor size (p < 0.01) and reduction of locoregional lymph node metastasis by combination treatment. These results were also consistent with inactivation of NF-κB and the downregulation of NF-κB downstream genes, decreased proliferation marker (Ki-67) and increased apoptosis (TUNEL) in tumor remnants, all of which was consistent with in vitro findings. From these results, we conclude that genistein sensitizes drug-resistant PC to OxP, which is mechanistically linked with inactivation of NF-κB signaling, resulting in greater antitumor effects, and thus our data suggest that this approach could be useful in improving the treatment outcome for patients diagnosed with PC.

CABYR RNAi plasmid construction and NF-κB signal transduction pathway

AIM: To construct the CABYR RNAi plasmid and study its relation with the nuclear factor (NF)-κB signal transduction pathway.

METHODS: Human CABYR mRNA sequence was obtained from GenBank. The structure of cDNA sequence for the short hairpin RNA was BbsI + sense + loop + antisense + transcription terminator + KpnI + BamHI. A CABYR silencing plasmid was constructed and transfected into the human embryo cell line 293T. Quantitative real-time polymerase chain reaction was used to analyze CABYR and NF-κB gene expression.

RESULTS: The CABYR and NF-κB expressions were detected in 293T cells. The oligonucleotide (5’-GCTCAGATGTTAGGTAAAG-3’) efficiently silenced the expression of CABYR. The expression of NF-κB was not significantly affected by silencing CABYR (P = 0.743).

CONCLUSION: CABYR can be found in the human embryo cell line 293T. Cabyrmid 2 can efficiently silence its target, CABYR, indicating that CABYR is not related with the NF-κB signal transduction pathway.

Kaempferol enhances cisplatin's effect on ovarian cancer cells through promoting apoptosis caused by down regulation of cMyc

Background

Ovarian cancer is one of the most significant malignancies in the western world. Studies showed that Ovarian cancers tend to grow resistance to cisplatin treatment. Therefore, new approaches are needed in ovarian cancer treatment. Kaempferol is a dietary flavonoid that is widely distributed in fruits and vegetables, and epidemiology studies have revealed a protective effect of kaempferol against ovarian cancer risk. Our early studies also found that kaempferol is effective in reducing vascular endothelial growth factor (VEGF) expression in ovarian cancer cells. In this study, we investigated kaempferol's effects on sensitizing ovarian cancer cell growth in response to cisplatin treatment.

Results

Ten chemicals were screened for sensitizing OVCAR-3 ovarian cancer cell growth in response to cisplatin treatment. For kaempferol, which shows a significant synergistic interaction with cisplatin, expression of ABCC1, ABCC5, ABCC6, NFkB1, cMyc, and CDKN1A genes was further examined. For cisplatin/kaempferol treatments on OVCAR-3 cancer cells, the mRNA levels of ABCC1, ABCC5, and NFkB1 did not change. However, significant inhibition of ABCC6 and cMyc mRNA levels was observed for the cisplatin/kaempferol combined treatment. The CDKN1A mRNA levels were significantly up-regulated by cisplatin/kaempferol treatment. A plot of CDKN1A mRNA levels against that of cMyc gene further revealed a reverse, linear relationship, proving cMyc's regulation on CDKN1A gene expressions. Our work found that kaempferol works synergistically with cisplatin in inhibiting ovarian cancer cell viability, and their inhibition on cell viabilities was induced through inhibiting ABCC6 and cMyc gene transcription. Apoptosis assay showed the addition of 20 μM kaempferol to the cisplatin treatment induces the apoptosis of the cancer cells.

Conclusions

Kaempferol enhances the effect of cisplatin through down regulation of cMyc in promoting apoptosis of ovarian cancer cells. As a dietary component, kaempferol sensitizes ovarian cancer cells to cisplatin treatment and deserves further studies for possible applications in chemotherapy of ovarian cancers.

Critical need for clinical trials: an example of a pilot human intervention trial of a mixture of natural agents protecting lymphocytes against TNF-alpha induced activation of NF-kappaB

Humans typically consume "natural agents" that are believed to be chemoprotective and are known to decrease inflammation biomarker NF-kappaB in vitro; however, no intervention studies in humans have been done to date. This commentary documents the in vivo results as a powerful example for supporting the superiority of a complex mixture of natural agents. Human volunteers consumed two 500 mg capsules (BID) containing a mixture of natural agents for a period of 2 weeks, and blood samples were collected pre- and post-intervention. The purified lymphocytes were subjected to ex-vivo exposure to TNF-alpha or kept as untreated control. The mean NF-kappaB DNA binding activity was increased upon TNF-alpha treatment in pre-intervention samples; however, TNF-alpha was unable to induce NF-kappaB in post-intervention samples, suggesting that the mixture of four important natural agents could be useful to protect humans against oxidative stress.

Preclinical studies of apogossypolone, a novel pan inhibitor of bcl-2 and mcl-1, synergistically potentiates cytotoxic effect of gemcitabine in pancreatic cancer cells

OBJECTIVE

Overexpression of antiapoptotic Bcl-2 family proteins confers resistance to conventional therapy in pancreatic cancer patients. Apogossypolone (ApoG2) is an analogue of (-)-gossypol, exhibiting binding activity with Ki values of 35 nmol/L for Bcl-2 and 25 nmol/L for Mcl-1. The present study was designed to test our hypothesis whether inactivation of Bcl-2 family of proteins using ApoG2 could sensitize pancreatic cancer cells to the cytotoxic effect of gemcitabine.

METHODS

Two pancreatic cancer cell lines were treated with ApoG2, gemcitabine, and their combination; cytotoxicity and apoptosis was confirmed by MTT and histone/DNA enzyme-linked immunosorbent assay. Coimmunoprecipitation experiments were performed to elucidate the mechanism of action of ApoG2. In vivo efficacy of ApoG2 was evaluated in a xenograft model to confirm its therapeutic benefit with gemcitabine.

RESULTS

When ApoG2 was combined with gemcitabine, increased cytotoxicity and apoptosis was evident. Coimmunoprecipitation experiment revealed that ApoG2 blocks the heterodimerization of Mcl-1/Bax and Bcl-2/Bim in cells. Furthermore, administration of ApoG2 with gemcitabine resulted in a statistically higher antitumor activity compared with either ApoG2 or gemcitabine alone in a severe combined immunodeficiency mouse xenograft model.

CONCLUSIONS

Apogossypolone, which functions as a potent pan-Bcl-2 family inhibitor, seems therapeutically promising for future translational studies including the treatment of pancreatic cancer.

Phytochemicals in cancer prevention and therapy: truth or dare?

A voluminous literature suggests that an increase in consumption of fruit and vegetables is a relatively easy and practical strategy to reduce significantly the incidence of cancer. The beneficial effect is mostly associated with the presence of phytochemicals in the diet. This review focuses on a group of them, namely isothiocyanate, curcumin, genistein, epigallocatechin gallate, lycopene and resveratrol, largely studied as chemopreventive agents and with potential clinical applications. Cellular and animal studies suggest that these molecules induce apoptosis and arrest cell growth by pleiotropic mechanisms. The anticancer efficacy of these compounds may result from their use in monotherapy or in association with chemotherapeutic drugs. This latter approach may represent a new pharmacological strategy against several types of cancers. However, despite the promising results from experimental studies, only a limited number of clinical trials are ongoing to assess the therapeutic efficacy of these molecules. Nevertheless, the preliminary results are promising and raise solid foundations for future investigations.

Enhanced anticancer effect of gemcitabine by genistein in osteosarcoma: the role of Akt and nuclear factor-kappaB

Genistein, a nontoxic flavonoid compound, has potent antitumor activity in various cancer cell lines. This study was designed to investigate whether combination therapy with gemcitabine and genistein enhances antitumor efficacy in osteosarcoma cell lines (MG-63 and U2OS). Our results show that significant reduction in cell viability and corresponding induction of apoptosis were observed with combination treatment in both cell lines. On the molecular level, we found that gemcitabine alone can activate nuclear factor kappaB (NF-kappaB) in osteosarcoma, suggesting the potential mechanism of acquired chemoresistance. In contrast, genistein reversed the cancer's resistance to gemcitabine through the downregulation of NF-kappaB activity and the suppression of Akt. These findings suggest that the combination of gemcitabine and genistein enhanced the antitumor efficacy by abrogating the Akt/NF-kappaB pathway. The marked ability to induce apoptosis with a combination of gemcitabine and genistein suggests that this could be a rational and novel approach for osteosarcoma preclinical and clinical trials.

Lipid raft cholesterol and genistein inhibit the cell viability of prostate cancer cells via the partial contribution of EGFR-Akt/p70S6k pathway and down-regulation of androgen receptor

Soy isoflavones and cholesterol have been reported as dietary factors related to the incidence of prostate cancer. In this study, we investigated whether cell survival could be suppressed by a combination of the dispersion of lipid raft microdomains and treatment with genistein, a well-known potential isoflavone, in LNCaP prostate cancer cells. Cell viability was assayed by the property of reagent change upon reduction of resazurin to resorufin and apoptosis was evaluated by ethidium bromide/acridine orange (EB/AO) staining and PARP and caspase-3 expression. Signal transduction was investigated by immunoblot analysis. Cell viability decreased significantly more following successive double treatment with genistein and the cholesterol-lowering agent 2-hydroxypropyl-beta-cyclodextrin (HPCD) than in response to either agent alone. Apoptotic cell staining and cleavage of PARP and caspase-3 appeared more clearly in double-treated cells than in those treated with genistein alone. In cell signaling, both HPCD and genistein decreased the protein expressions of pAkt as well as the androgen receptors stimulated by EGF and DHT, respectively, in concentration-dependent manners. This pattern was also present in protein levels of pAkt and the androgen receptor located in the lipid raft fraction. Furthermore, the phosphorylation cascade of Akt, GSK-3beta and p70S6k was markedly inhibited by the combination treatment. These data suggest that prostate cancer cells could be effectively inhibited by combination treatment of cholesterol-lowering strategies and genistein. The mechanism is likely to be partially via both the EGFR-mediated Akt or p70S6k pathways and a down-regulation of androgen receptor in the lipid raft microdomain.

Dihydroartemisinin inactivates NF-kappaB and potentiates the anti-tumor effect of gemcitabine on pancreatic cancer both in vitro and in vivo

Gemcitabine is currently the best known chemotherapeutic option available for pancreatic cancer, but the tumor returns de novo with acquired resistance over time, which becomes a major issue for all gemcitabine-related chemotherapies. In this study, for the first time, we demonstrated that dihydroartemisinin (DHA) enhances gemcitabine-induced growth inhibition and apoptosis in both BxPC-3 and PANC-1 cell lines in vitro. The mechanism is at least partially due to DHA deactivates gemcitabine-induced NF-kappaB activation, so as to decrease tremendously the expression of its target gene products, such as c-myc, cyclin D1, Bcl-2, Bcl-xL. In our in vivo studies, gemcibabine also manifested remarkably enhanced anti-tumor effect when combined with DHA, as manifested by significantly increased apoptosis, as well as decreased Ki-67 index, NF-kappaB activity and its related gene products, and predictably, significantly reduced tumor volume. We concluded that inhibition of gemcitabine-induced NF-kappaB activation is one of the mechanisms that DHA dramatically promotes its anti-tumor effect on pancreatic cancer.

Isoflavones are safe compounds for therapeutical applications - evaluation of in vitro data

Isoflavone-rich food and food supplements have gained increasing popularity also in the Western world. Their weak estrogenic effect has been considered as a potential risk, although all epidemiological studies and clinical trials show a significant cancer protection and decreased risk of cardiovascular diseases. In vitro data suggest that the concerted action of the isoflavones and their metabolites show antiproliferative behaviour, reduce angiogenesis, reduce tumor progression and exert antiinflammatory effects. For the evaluation of the biological effects, special emphasis has to be put on the concerted action between the isoflavones and their metabolites. For instance, while isolated genistein shows some growth promoting effect at low concentrations, the metabolite equol or soy extract show growth retardation as well as higher concentrations of genistein do. The isoflavones have multiple affinities to other members of the steroid hormone receptor superfamily. The beneficial effect on metabolic diseases and weight reduction by isoflavone consumption can be partly explained by its affinity for the PPAR family. In light of the in vitro experiments, together with the epidemiological observations and the clinical experience, isoflavones can be considered as safe compounds and their consumption as food and food supplements has to be promoted.

Flavonoids, phenoxodiol, and a novel agent, triphendiol, for the treatment of pancreaticobiliary cancers

Flavonoids, in particular the isoflavones, are naturally occurring compounds found in soy and textured vegetables that have antiproliferative effects on a variety of cancer types. Phenoxodiol is a derivative of the isoflavone genisten that is 5-20 times more potent than genisten. Triphendiol is a derivative of phenoxodiol that has superior anticancer activity against pancreatic and bile duct cancers. This review will focus on the mechanisms of action and activity of two isoflavone derivatives, phenoxodiol and triphendiol, in various tumor types, especially pancreaticobiliary cancers. Triphendiol induces apoptosis in pancreatic cell lines by both caspase-mediated and caspase-independent mechanisms. The addition of triphendiol to gemcitabine is synergistic in in vitro and in vivo models of pancreatic cancer and represents a novel combination of drugs for pancreatic cancer patients.

3,3'-Diindolylmethane enhances chemosensitivity of multiple chemotherapeutic agents in pancreatic cancer

Clinical management of pancreatic cancer is a major problem, which is in part due to both de novo and acquired resistance to conventional therapeutics. Here, we present in vitro and in vivo preclinical evidence in support of chemosensitization of pancreatic cancer cells by 3,3-diindolylmethane (DIM), a natural compound that can be easily obtained by consuming cruciferous vegetables. DIM pretreatment of pancreatic cancer cells led to a significantly increased apoptosis (P < 0.01) with suboptimal concentrations of chemotherapeutic agents (cisplatin, gemcitabine, and oxaliplatin) compared with monotherapy. It is known that resistance to chemotherapy in pancreatic cancer is associated with constitutively activated nuclear factor-kappaB (NF-kappaB), which becomes further activated by chemotherapeutic drugs. Our data provide mechanistic evidence for the first time showing that DIM potentiates the killing of pancreatic cancer cells by down-regulation of constitutive as well as drug-induced activation of NF-kappaB and its downstream genes (Bcl-xL, XIAP, cIAP, and survivin). Most importantly, using an orthotopic animal model, we found reduction in tumor size (P < 0.001) when DIM was given in combination with oxaliplatin compared with monotherapy. This was accompanied by loss of phospho-p65 and down-regulation of NF-kappaB activity and its downstream genes (Bcl-xL, survivin, and XIAP), which correlated with reduced cell proliferation (as assessed by Ki-67 immunostaining of tumor specimens) and evidence of apoptosis [as assessed by poly(ADP-ribose) polymerase cleavage and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining]. These results provide strong in vivo evidence in support of our hypothesis that DIM could abrogate chemotherapeutic drug (cisplatin, gemcitabine, and/or oxaliplatin)-induced activation of NF-kappaB, resulting in the chemosensitization of pancreatic tumors to conventional therapeutics.

NFkappaB signaling in carcinogenesis and as a potential molecular target for cancer therapy

It has become increasingly clear that deregulation of the NFkappaB signaling cascade is a common underlying feature of many human ailments including cancers. The past two decades of intensive research on NFkappaB has identified the basic mechanisms that govern the functioning of this pathway but uncovering the details of why this pathway works differently in different cellular contexts or how it interacts with other signaling pathways remains a challenge. A thorough understanding of these processes is needed to design better and more efficient therapeutic approaches to treat complex diseases like cancer. In this review, we summarize the literature documenting the involvement of NFkappaB in cancer, and then focus on the approaches that are being undertaken to develop NFkappaB inhibitors towards treatment of human cancers.