Cisplatin-induced antitumor activity is potentiated by the soy isoflavone genistein in BxPC-3 pancreatic tumor xenografts

Phyto-targeting the CEMIP Expression as a Strategy to Prevent Pancreatic Cancer Metastasis

INTRODUCTION

Metastasis of primary pancreatic cancer (PC) to adjacent or distant organs is responsible for the poor survival rate of affected individuals. Chemotherapy, radiotherapy, and immunotherapy are currently being prescribed to treat PC in addition to surgical resection. Surgical resection is the preferred treatment for PC that leads to 20% of 5-year survival, but only less than 20% of patients are eligible for surgical resection because of the poor prognosis. To improve the prognosis and clinical outcome, early diagnostic markers need to be identified, and targeting them would be of immense benefit to increase the efficiency of the treatment. Cell migration-inducing hyaluronan-binding protein (CEMIP) is identified as an important risk factor for the metastasis of various cancers, including PC. Emerging studies have pointed out the crucial role of CEMIP in the regulation of various signaling mechanisms, leading to enhanced migration and metastasis of PC.

METHODS

The published findings on PC metastasis, phytoconstituents, and CEMIP were retrieved from Pubmed, ScienceDirect, and Cochrane Library. Computational tools, such as gene expression profiling interactive analysis (GEPIA) and Kaplan-Meier (KM) plotter, were used to study the relationship between CEMIP expression and survival of PC individuals.

RESULTS

Gene expression analysis using the GEPIA database identified a stupendous increase in the CEMIP transcript in PC compared to adjacent normal tissues. KM plotter analysis revealed the impact of CEMIP on the overall survival (OS) and disease-free survival (DFS) among PC patients. Subsequently, several risk factors associated with PC development were screened, and their ability to regulate CEMIP gene expression was analyzed using computational tools.

CONCLUSION

The current review is focused on gathering information regarding the regulatory role of phytocomponents in PC migration and exploring their possible impact on the CEMIP expression.

Synergistic Effect of Barbadensis miller and Marsdenia Condurango Extracts Induces Apoptosis Promotes Oxidative Stress by Limiting Proliferation of Cervical Cancer and Liver Cancer Cells

Background:

Drug synergy is the combine effect of drug efficacy. Synergistic combinations of active ingredients have proven to be highly effective and more useful in therapeutics. In contrast, the individual effect of drug is usually undesirable and mostly used for selecting drug-resistant mutations. Purpose of this study was to check synergistic effects of both plants (Barbadensis miller and Marsdenia condurango) against liver and cervical cancer.

Methodology:

Culturing of HeLa (cervical cancer cell line) and HepG2 (liver cancer cell line) cells, IC₅₀ evaluation, viability assays (trypan blue, crystal violet), p53 ELISA and immunocytochemistry, MUSE analysis (count and viability), antioxidants (GSH, SOD, CAT), at the end RT-PCR was performed.

Results:

IC₅₀ evaluation was done of each plant individually and with combination for synergistic effects, IC₅₀ with plants combination (synergism) was applied on further viability assays (trypan blue, crystal violet, MUSE analysis via count and viability kit) p53 ELISA and immunocytochemistry for evaluation of cellular apoptosis, antioxidants assays (GSH, SOD, CAT), and RT-PCR with proliferative and apoptotic markers along with internal control.

Conclusion:

According to current study it was observed that synergistic effect of these plants has more anticancer properties with minimum effective dose. It was also observed that extracts possess the ability to induce apoptosis, restrict proliferation and enhanced oxidative stress.

Evaluation of nuclear NF-κB, transglutaminase2, and ERCC1 as predictors of platinum resistance in testicular tumors

PURPOSE

Testicular germ cells tumor (TGCT) are associated with a high cure rate and are treated with platinum-based chemotherapy. However, a group of testicular cancer patients may have a very unfavorable evolution and insensitivity to the main therapeutic agent chemotherapy (CT) cisplatin. The aim of this study was to evaluate the risk of recurrence and overall survival related to the expression of nuclear factor kappa-B (NF-κB), transglutaminase 2 (TG2) and excision repair cross-complementation group 1 (ERCC1) in patients with TGCT treated with platinum combinations.

PATIENTS AND METHODS

A retrospective study was performed with TGCT patients treated with platinum-based chemotherapy. Immunohistochemical analysis was performed and the expression was correlated with clinical and laboratory data.

RESULTS

Fifty patients were included, the mean age was 28.4 years (18 to 45), and 76% were non-seminoma. All patients were treated with standard cisplatin, etoposide and bleomycin or cisplatin, and etoposide. Patient's analyzed immunodetection for NF-κB, TG2, and ERCC1 were positive in 76%, 54% and 42%, respectively. Multivariate analysis identified that positive expressions to ERCC1 and NF-κB are independent risk factors for higher recurrence TGCT after chemotherapy (RR 2.96 and 3.16, respectively). Patients with positive expression of ERCC1 presented a poor overall survival rate for 10-year follow (p=0.001).

CONCLUSIONS

The expression of ERCC1 and NF-κB give a worse prognosis for relapse, and only ERCC1 had an influence on the overall survival of TGCT patients treated with platinum-based chemotherapy. These may represent markers that predict poor clinical outcome and response to cisplatin.

Synergistic Effects of Plant Derivatives and Conventional Chemotherapeutic Agents: An Update on the Cancer Perspective

Synergy is a process in which some substances cooperate to reach a combined effect that is greater than the sum of their separate effects. It can be considered a natural "straight" strategy which has evolved by nature to obtain more efficacy at low cost. In this regard, synergistic effects may be observed in the interaction between herbal products and conventional drugs or biochemical compounds. It is important to identify and exploit these interactions since any improvement brought by such kind of process can be advantageously used to treat human disorders. Even in a complex disease such as cancer, positive synergistic plant-drug interactions should be investigated to achieve the best outcomes, including providing a greater benefit to patients or avoiding adverse side effects. This review analyzes and summarizes the current knowledge on the synergistic effects of plant-drug interactions with a focus on anticancer strategies.

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.

Pharmacokinetics and Biliary Excretion of Fisetin in Rats

The hypothesis of this study is that fisetin and phase II conjugated forms of fisetin may partly undergo biliary excretion. To investigate this hypothesis, male Sprague-Dawley rats were used for the experiment, and their bile ducts were cannulated with polyethylene tubes for bile sampling. The pharmacokinetic results demonstrated that the average area-under-the-curve (AUC) ratios ( k (%) = AUC_conjugate/AUC_free-form) of fisetin, its glucuronides, and its sulfates were 1:6:21 in plasma and 1:4:75 in bile, respectively. Particularly, the sulfated metabolites were the main forms that underwent biliary excretion. The biliary excretion rate ( k_BE (%) = AUC_bile/AUC_plasma) indicates the amount of fisetin eliminated by biliary excretion. The biliary excretion rates of fisetin, its glucuronide conjugates, and its sulfate conjugates were approximately 144, 109, and 823%, respectively, after fisetin administration (30 mg/kg, iv). Furthermore, biliary excretion of fisetin is mediated by P-glycoprotein.

Is metastatic pancreatic cancer an untargetable malignancy?

Metastatic pancreatic cancer (MPC) is one of the most aggressive malignancies, known to be chemo-resistant and have been recently considered resistant to some targeted therapies (TT). Erlotinib combined to gemcitabine is the only targeted therapy that showed an overall survival benefit in MPC. New targets and therapeutic approaches, based on new-TT, are actually being evaluated in MPC going from immunotherapy, epigenetics, tumor suppressor gene and oncogenes to stromal matrix regulators. We aim in this paper to present the major causes rendering MPC an untargetable malignancy and to focus on the new therapeutic modalities based on TT in MPC.

Cyp4 A2, Apoa1, ANXA2 and DPYD are involved in anti-fibrotic effects of genistein in rats

AIM: To investigate the molecular mechanism of genistein in therapy of CCl₄-induced liver fibrosis in rats by utilizing isobaric tags for relative and absolute quantitation (iTRAQ) coupled with liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS).

METHODS: SD rats were randomly divided into a control group, a model group and a genistein therapy group. The rats of the model group and genistein therapy group were given intragastric administration of 50% CCl₄ for 15 wk to induce liver fibrosis. Genistein therapy was started at the 9^th week and lasted for 6 wk. Proteins differentially expressed in the tissue were identified by iTRAQ coupled with LC-ESI-MS/MS technology and analyzed with bioinformatics tools. The expression of representative differentia1 protein (Cyp4 A2 and A1) was validated by Western blot.

RESULTS: A total of 585 proteins were identified by MS, of which 63 were differentially expressed, including 32 up-regulated and 31 down-regulated ones. The differentially expressed proteins are involved in post-translational modification, transcription, recombination and signal transduction pathways. The tissue level of Cyp4 A2 decreased significantly in genistein therapy group compared with the model group, but Apoa1 showed a reverse trend.

CONCLUSION: Genistein can impact rat tissue protein expression. The antifibrotic effects of genistein may be due to regulation of protein expression.

Phytochemicals as Innovative Therapeutic Tools against Cancer Stem Cells

The theory that several carcinogenetic processes are initiated and sustained by cancer stem cells (CSCs) has been validated, and specific methods to identify the CSCs in the entire population of cancer cells have also proven to be effective. This review aims to provide an overview of recently acquired scientific knowledge regarding phytochemicals and herbal extracts, which have been shown to be able to target and kill CSCs. Many genes and proteins that sustain the CSCs’ self-renewal capacity and drug resistance have been described and applications of phytochemicals able to interfere with these signaling systems have been shown to be operatively efficient both in vitro and in vivo. Identification of specific surface antigens, mammosphere formation assays, serial colony-forming unit assays, xenograft transplantation and label-retention assays coupled with Aldehyde dehydrogenase 1 (ALDH1) activity evaluation are the most frequently used techniques for measuring phytochemical efficiency in killing CSCs. Moreover, it has been demonstrated that EGCG, curcumin, piperine, sulforaphane, β-carotene, genistein and the whole extract of some plants are able to kill CSCs. Most of these phytochemicals act by interfering with the canonical Wnt (β-catenin/T cell factor-lymphoid enhancer factor (TCF-LEF)) pathway implicated in the pathogenesis of several cancers. Therefore, the use of phytochemicals may be a true therapeutic strategy for eradicating cancer through the elimination of CSCs.

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.

Oxidative stress and cytokines in the pathogenesis of pancreatic cancer

Pancreatic cancer is one of the most aggressive, drug-resistant and lethal types of cancer with poor prognosis. Various factors including reactive oxygen species, cytokines, growth factors, and extracellular matrix proteins are reported to be involved in the development of pancreatic cancer. However, the pathogenesis of pancreatic cancer has not been completely elucidated. Oxidative stress has been shown to contribute to the development of pancreatic cancer. Evidences supporting the role of reactive oxygen species and cytokines as a risk for pancreatic cancer and the concept of antioxidant supplementation as a preventive approach for pancreatic cancer have been proposed. Here, we review the literature on oxidative stress, cytokine expression, inflammatory signaling, and natural antioxidant supplementation in relation to pancreatic cancer.

Genistein enhances the effect of cisplatin on the inhibition of non-small cell lung cancer A549 cell growth in vitro and in vivo

Although cisplatin (DDP) has been reported to be a promising antitumor therapy for non-small cell lung cancer (NSCLC), the effectiveness of the treatment remains limited due to an inherent tumor resistance to DDP. Genistein (GEN) is an abundant, naturally occurring isoflavonoid found in soy products that has been demonstrated to increase the anti-neoplastic activity of certain chemotherapy drugs in multiple tumor types. In the present study, DDP in combination with GEN was selected as a potential treatment to suppress tumor growth and simultaneously reduce the doses of the two drugs required for the treatment of NSCLC. Cell growth inhibition, apoptosis, cell cycle distribution and receptor signaling assays were conducted. In the in vivo study, DDP and GEN, either alone or in combination, were used to treat a xenograft model of the A549 cells. It was found that the combination of low concentrations of DDP and GEN induced significantly greater growth inhibition (P<0.01) and increased apoptosis in the A549 cells compared with either agent alone. In addition, DDP in combination with GEN could significantly suppress tumor growth in vivo compared with either agent alone. Combination treatment significantly suppresses constitutive phosphorylation of AKT and phosphoinositide-3 kinase, which may contribute to the inhibition of tumor growth. Overall, the present data suggested that GEN can increase the anti-neoplastic activity of DDP and that a combination of GEN and DDP is a potential drug candidate for the treatment of NSCLC.

RAD51 potentiates synergistic effects of chemotherapy with PCI-24781 and cis-diamminedichloroplatinum on gastric cancer

AIM: To explore the efficacy of PCI-24781, a broad-spectrum, hydroxamic acid-derived histone deacetylase inhibitor, in the treatment of gastric cancer (GC).

METHODS: With or without treatment of PCI-24781 and/or cis-diamminedichloroplatinum (CDDP), GC cell lines were subjected to functional analysis, including cell growth, apoptosis and clonogenic assays. Chromatin immunoprecipitation and luciferase reporter assays were used to determine the interacting molecules and the activity of the enzyme. An in vivo study was carried out in GC xenograft mice. Cell culture-based assays were represented as mean ± SD. ANOVA tests were used to assess differences across groups. All pairwise comparisons between tumor weights among treatment groups were made using the Tukey-Kramer method for multiple comparison adjustment to control experimental-wise type I error rates. Significance was set at P < 0.05.

RESULTS: PCI-24781 significantly reduced the growth of the GC cells, enhanced cell apoptosis and suppressed clonogenicity, and these effects synergized with the effects of CDDP. PCI-24781 modulated the cell cycle and significantly reduced the expression of RAD51, which is related to homologous recombination. Depletion of RAD51 augmented the biological functions of PCI-24781, CDDP and the combination treatment, whereas overexpressing RAD51 had the opposite effects. Increased binding of the transcription suppressor E2F4 on the RAD51 promoter appeared to play a major role in these processes. Furthermore, significant suppression of tumor growth and weight in vivo was obtained following PCI-24781 treatment, which synergized with the anticancer effect of CDDP.

CONCLUSION: These data suggest that RAD51 potentiates the synergistic effects of chemotherapy with PCI-24781 and CDDP on GC.

Proteomic analysis of A2780/S ovarian cancer cell response to the cytotoxic organogold(III) compound Aubipy(c)

Aubipyc is an organogold(III) compound endowed with encouraging anti-proliferative properties in vitro that is being evaluated pre-clinically as a prospective anticancer agent. A classical proteomic approach is exploited here to elucidate the mechanisms of its biological actions in A2780 human ovarian cancer cells. Based on 2-D gel electrophoresis separation and subsequent mass spectrometry identification, a considerable number of differentially expressed proteins were highlighted in A2780 cancer cells treated with Aubipyc. Bioinformatic analysis of the groups of up-regulated and down-regulated proteins pointed out that Aubipyc primarily perturbs mitochondrial processes and the glycolytic pathway. Notably, some major alterations in the glycolytic pathway were validated through Western blot and metabolic investigations.

BIOLOGICAL SIGNIFICANCE

This is the first proteomic analysis regarding Aubipyc cytotoxicity in A2780/S ovarian cancer cell line. Aubipyc is a promising gold(III) compound which manifests an appreciable cytotoxicity toward the cell line A2780, being able to overcome resistance to platinum. The proteomic study revealed for Aubipyc different cellular alterations with respect to cisplatin as well as to other gold compound such as auranofin. Remarkably, the bioinformatic analysis of proteomic data pointed out that Aubipyc treatment affected, directly or indirectly, several glycolytic enzymes. These data suggest a new mechanism of action for this gold drug and might have an impact on the use of gold-based drug in cancer treatment.

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.

Bioavailability and pharmacokinetics of genistein: mechanistic studies on its ADME

Genistein, one of the most active natural flavonoids, exerts various biological effects including chemoprevention, antioxidation, antiproliferation and anticancer. More than 30 clinical trials of genistein with various disease indications have been conducted to evaluate its clinical efficacy. Based on many animals and human pharmacokinetic studies, it is well known that the most challenge issue for developing genistein as a chemoprevention agent is the low oral bioavailability, which may be the major reason relating to its ambiguous therapeutic effects and large interindividual variations in clinical trials. In order to better correlate pharmacokinetic to pharmacodynamics results in animals and clinical studies, an in-depth understanding of pharmacokinetic behavior of genistein and its ADME properties are needed. Numerous in vitro/in vivo ADME studies had been conducted to reveal the main factors contributing to the low oral bioavailability of genistein. Therefore, this review focuses on summarizing the most recent progress on mechanistic studies of genistein ADME and provides a systemic view of these processes to explain genistein pharmacokinetic behaviors in vivo. The better understanding of genistein ADME property may lead to development of proper strategy to improve genistein oral bioavailability via mechanism-based approaches.

Oroxylin A prevents inflammation-related tumor through down-regulation of inflammatory gene expression by inhibiting NF-κB signaling

Increasing evidence suggests that inflammatory microenvironment plays a critical role at different stages of tumor development. However, the molecular mechanisms of the interaction between inflammation and proliferation of cancer cells remain poorly defined. Here we reported the inhibitory effects of oroxylin A on the inflammation-stimulated proliferation of tumor cells and delineated the mechanism of its action. The results indicated that treatment with oroxylin A inhibited NF-κB p65 nuclear translocation and phosphorylation of IκBα and IKKα/β in both human colon tumor HCT116 cells and human monocytes THP-1 cells. In addition, in THP-1 cells, oroxylin A significantly suppressed lipopolysaccharide (LPS)-induced secretion of prototypical proinflammatory cytokine IL-6 but not IL-1β, and it was confirmed at the transcription level. Moreover, oroxylin A inhibited the proliferation of HCT116 cells stimulated by LPS-induced THP-1 cells in co-culture microenvironment. In summary, oroxylin A modulated NF-κB signaling pathway involved in inflammation-induced cancer initiation and progression and therefore could be a potential cancer chemoprevention agent for inflammation-related cancer.

Current knowledge on pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months and a dismal 5-year survival rate of 3-5%. The development and progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways. Therefore, the strategies targeting these molecules as well as their downstream signaling could be promising for the prevention and treatment of pancreatic cancer. However, although targeted therapies for pancreatic cancer have yielded encouraging results in vitro and in animal models, these findings have not been translated into improved outcomes in clinical trials. This failure is due to an incomplete understanding of the biology of pancreatic cancer and to the selection of poorly efficient or imperfectly targeted agents. In this review, we will critically present the current knowledge regarding the molecular, biochemical, clinical, and therapeutic aspects of pancreatic cancer.

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.

Cytoplasmic overexpression of CD95L in esophageal adenocarcinoma cells overcomes resistance to CD95-mediated apoptosis

INTRODUCTION

The CD95/CD95L pathway plays a critical role in tissue homeostasis and immune system regulation; however, the function of this pathway in malignancy remains poorly understood. We hypothesized that CD95L expression in esophageal adenocarcinoma confers advantages to the neoplasm other than immune privilege.

METHODS

CD95L expression was characterized in immortalized squamous esophagus (HET-1A) and Barrett esophagus (BAR-T) cells; adenocarcinoma cell lines FLO-1, SEG-1, and BIC-1, and MDA468 (- control); and KFL cells (+ control). Analyses included reverse transcription-polymerase chain reaction, immunoblots of whole cell and secretory vesicle lysates, FACScan analysis, laser scanning confocal microscopy of native proteins and fluorescent constructs, and assessment of apoptosis and ERK1/2 pathways.

RESULTS

Cleaved, soluble CD95L is expressed at both the RNA and protein levels in these cell lines derived from esophageal adenocarcinoma and other human tissues. CD95L was neither trafficked to the cell membrane nor secreted into the media or within vesicles, rather the protein seems to be sequestered in the cytoplasm. CD95 and CD95L colocalize by immunofluorescence, but an interaction was not proven by immunoprecipitation. Overexpression of CD95L in the adenocarcinoma cell lines induced robust apoptosis and, under conditions of pan-caspase inhibition, resulted in activation of ERK signaling.

CONCLUSIONS

CD95L localization in EA cells is inconsistent with the conference of immune privilege and is more consistent with a function that promotes tumor growth through alternative CD95 signaling. Reduced cell surface expression of CD95 affects cell sensitivity to extracellular apoptotic signals more significantly than alterations in downstream modulators of apoptosis.

Cisplatin as an anti-tumor drug: cellular mechanisms of activity, drug resistance and induced side effects

Platinum complexes are clinically used as adjuvant therapy of cancers aiming to induce tumor cell death. Depending on cell type and concentration, cisplatin induces cytotoxicity, e.g., by interference with transcription and/or DNA replication mechanisms. Additionally, cisplatin damages tumors via induction of apoptosis, mediated by the activation of various signal transduction pathways, including calcium signaling, death receptor signaling, and the activation of mitochondrial pathways. Unfortunately, neither cytotoxicity nor apoptosis are exclusively induced in cancer cells, thus, cisplatin might also lead to diverse side-effects such as neuro- and/or renal-toxicity or bone marrow-suppression. Moreover, the binding of cisplatin to proteins and enzymes may modulate its biochemical mechanism of action. While a combination-chemotherapy with cisplatin is a cornerstone for the treatment of multiple cancers, the challenge is that cancer cells could become cisplatin-resistant. Numerous mechanisms of cisplatin resistance were described including changes in cellular uptake, drug efflux, increased detoxification, inhibition of apoptosis and increased DNA repair. To minimize cisplatin resistance, combinatorial therapies were developed and have proven more effective to defeat cancers. Thus, understanding of the biochemical mechanisms triggered by cisplatin in tumor cells may lead to the design of more efficient platinum derivates (or other drugs) and might provide new therapeutic strategies and reduce side effects.

Soy isoflavones ameliorate the adverse effects of chemotherapy in children

Genistein sensitizes cancer cells to chemotherapy and radiation by modulating cell survival pathways. At the same time, genistein's antioxidant and anti-inflammatory effects may protect normal tissues from adverse effects of chemotherapy and radiation, which are largely due to oxygen-free radicals and inflammation. We conducted a small pilot study with a soy isoflavone mixture containing 8 mg of genistein in children receiving chemotherapy and/or radiation to investigate genistein's potential toxicity preventive effect. We monitored clinical and laboratory parameters in children with cancer who received their first cycle of chemotherapy without genistein and the subsequent cycles with genistein. Patients served as their own controls, and the clinical-laboratory data from the first cycle were compared to the data from subsequent cycles. Nine cycles of chemotherapy were administered without genistein and 57 cycles with genistein. Patients experienced less myelosuppression, mucositis, and infection when they received genistein with chemotherapy. During supplementation, serum genistein levels were 2 to 6 times higher compared to presupplementation levels. Patients who received abdominal radiation reported less pain and diarrhea when they took the genistein supplement. Further clinical investigation of soy isoflavones in pediatric cancer patients receiving chemotherapy and/or radiation should be conducted.

N-(4-Hydroxyphenyl) Retinamide Potentiated Anti-tumor Efficacy of Genistein in Human Ewing's Sarcoma Xenografts

Background

Ewing’s sarcoma is a pediatric tumor that mainly occurs in soft tissues and bones. New therapeutic strategies are urgently needed for treatment of Ewing’s sarcoma. We examined for the first time the efficacy of N-(4-hydroxyphenyl) retinamide (4-HPR) and genistein (GST) alone and also in combination for controlling growth of human Ewing’s sarcoma SK-N-MC and RD-ES xenografts.

Methods

Efficacy of combination therapy was evaluated using histopathological parameters. Molecular mechanisms of combination therapy were detected using Western blotting and immunofluorescence microscopy.

Results

Histopathological examination of tumor sections showed that control group maintained characteristic growth of tumors, 4-HPR alone inhibited proliferation of tumor cells, GST alone induced apoptosis to some extent, and combination of 4-HPR and GST significantly induced apoptosis in both Ewing’s sarcoma xenografts. Time-dependent reductions in body weight, tumor volume, and tumor weight were also found. Combination therapy increased Bax : Bcl-2 ratio to trigger mitochondrial release of Smac/Diablo into the cytosol to downregulate the baculovirus inhibitor-of-apoptosis repeat containing (BIRC) proteins such as BIRC-2 and BIRC-3 and thereby promote apoptosis. Activation of caspase-3 and mitochondrial release of apoptosis-inducing factor (AIF) occurred in course of apoptosis. Downregulation of the survival factor NF-κB and the angiogenic factors VEGF and FGF2 and increase in caspase-3 activity controlled tumor growth. In situ immunofluorescent labelings showed overexpression of calpain, caspase-12 and caspase-3, and AIF in xenografts, indicating induction of cysteine proteases and AIF for apoptosis.

Conclusions

Results revealed that combination of 4-HPR and GST could be highly effective treatment for inhibiting Ewing’s sarcomas in vivo.

Dietary supplements and human health: for better or for worse?

Encouraged by the potential health benefits of higher dietary intake of substances with beneficial properties, the use of supplements containing these compounds has increased steadily over recent years. The effects of several of these, many of which are antioxidants, have been supported by data obtained in vitro, in animal models, and often by human studies as well. However, as carefully controlled human supplementation trials have been conducted, questions about the efficacy and safety of these supplements have emerged. In this Educational Paper, three different supplements were selected for consideration of the benefits and risks currently associated with their intake. The selected supplements include β-carotene, selenium, and genistein. The use of each is discussed in the context of preclinical and clinical data that provide evidence for both their use in reducing disease incidence and the possible liabilities that accompany their enhanced consumption. Variables that may influence their impact, such as lifestyle habits, baseline nutritional levels, and genetic makeup are considered and the application of these issues to broader classes of supplements is discussed.

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.

Cancer prevention with natural compounds

Botanical and nutritional compounds have been used for the treatment of cancer throughout history. These compounds also may be useful in the prevention of cancer. Population studies suggest that a reduced risk of cancer is associated with high consumption of vegetables and fruits. Thus, the cancer chemopreventive potential of naturally occurring phytochemicals is of great interest. There are numerous reports of cancer chemopreventive activity of dietary botanicals, including cruciferous vegetables such as cabbage and broccoli, Allium vegetables such as garlic and onion, green tea, Citrus fruits, soybeans, tomatoes, berries, and ginger, as well as medicinal plants. Several lead compounds, such as genistein (from soybeans), lycopene (from tomatoes), brassinin (from cruciferous vegetables), sulforaphane (from asparagus), indole-3-carbinol (from broccoli), and resveratrol (from grapes and peanuts) are in preclinical or clinical trials for cancer chemoprevention. Phytochemicals have great potential in cancer prevention because of their safety, low cost, and oral bioavailability. In this review, we discuss potential natural cancer preventive compounds and their mechanisms of action.

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.

Effects of genistein on cell proliferation and TGF-β1, MMP-2 and TIMP-2 expression in rat hepatic stellate cells

AIM: To investigate the effects of genistein on cell proliferation and the expression of transforming growth factor-β1 (TGF-β1), matrix metalloproteinase-2 (MMP-2) and tissue inhibitors of metalloproteinase-2 (TIMP-2) in rat hepatic stellate cell (HSC) and explore its possible anti-fibrogenic mechanism.

METHODS: After cultured HSC-T6 cells were exposed to different concentrations of genistein for 24 h, cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay, and the expression of TGF-β1, MMP-2 and TIMP-2 mRNAs was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Genistein at concentrations of 12.5, 25 and 50 mg/L significantly inhibited cell proliferation (0.306 ± 0.0067, 0.256 ± 0.0085, and 0.1316 ± 0.0049 vs 0.4468 ± 0.0299, respectively; all P < 0.05). Compared with untreated cells, the expression of MMP-2 mRNA was markedly upregulated (all P < 0.05), and the expression of TGF-β1 and TIMP-2 mRNAs was markedly dowregulated (all P < 0.05) in HSCs treated with different concentrations of genistein.

CONCLUSION: Genistein exerts anti-fibrogenic effects perhaps by inhibiting the expression of TGF-β1 and TIMP-2 mRNAs and increasing the expression of MMP-2 mRNA in HSCs in rats.

The effect of genistein aglycone on cancer and cancer risk: a review of in vitro, preclinical, and clinical studies

In Asian epidemiological studies, health benefits, including reduced incidence of breast and prostate cancers, are attributed to soy food and isoflavone consumption. The recent increased intake of soy foods and supplements in the American diet has raised concerns about the possible estrogen-like effects of natural isoflavones and possible promotion or propagation of estrogen-sensitive cancers. These concerns are primarily based on in vitro and rodent data which suggest that genistein aglycone can stimulate tumor cell proliferation and growth in mice having deficient immune systems. In contrast, a recent nested case-control study and meta-analysis of numerous epidemiological studies show an inverse correlation between genistein intake and breast cancer risk. Furthermore, clinical studies in osteopenic and osteoporotic, postmenopausal women support the breast and uterine safety of purified naturally derived genistein administered for up to 3 years. In this review, we summarize the in vitro, preclinical and clinical evidence for the safety of natural genistein.

Drug-regulatable cancer cell death induced by BID under control of the tissue-specific, lung cancer-targeted TTS promoter system

Gene therapy and virotherapy are among the approaches currently being used to treat lung cancer. The success of cancer gene therapy depends on treatments where different types of tumors can be selectively targeted and destroyed without affecting normal cells and tissue. Previously, we described a promoter system (TTS) that we designed that is specifically targeted to lung cancer cells but which does not affect other types of cells including stem cells. In our study, we have enhanced the utility of the TTS system by inserting the pro-apoptotic gene BH3 domain interacting death agonist (Bid) into the TTS promoter system (TTS/Bid) to create a drug regulatable lung cancer-specific gene therapy. A recombinant adenoviral vector was used to introduce TTS/Bid (Ad-TTS/Bid) into lung cancer cells. BID expression and apoptosis occurred in A549 pulmonary adenocarcinoma cells but little Bid expression or apoptosis occurred in MCF7 breast cancer cells or in normal human lung fibroblasts. The use of cisplatin enhanced the processing of full length BID to t-BID which significantly increased lung cancer-specific cell death. In in vivo experiments, intraperitonal injection of cisplatin enhanced the antitumor effects of the vector in a lung cancer xeno-graft mouse model. Moreover, dexamethasone effectively suppressed exogenous BID expression and the antitumor effect of Ad-TTS/Bid both in vitro and in vivo. Here, we describe the efficacy of the use of cisplatin and dexamethasone with the anti lung cancer promoter system (Ad-TTS/Bid) for a safe and effective gene therapy against advanced lung 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.

Perspectives for cancer prevention with natural compounds

Cancer is the second leading cause of death in the United States. Despite the estimated 565,650 deaths in 2008 of Americans as a result of cancer, it is mostly a preventable disease. Simply by modification of diet, maintenance of optimum body weight, and regular physical activity, 30% to 40% of all instances of cancer could be prevented. Modification of diet alone by increasing vegetable and fruit intake could prevent 20% or more of all cases of cancer and may potentially prevent approximately 200,000 cancer-related deaths annually. Because of their safety, low toxicity, antioxidant properties, and general acceptance as dietary supplements, fruits, vegetables, and other dietary elements (phytochemicals and minerals) are being investigated for the prevention of cancer. Extensive research over the past several decades has identified numerous dietary and botanical natural compounds that have chemopreventive potential. In this review, we discuss promising natural chemopreventive compounds, their molecular targets, and their mechanisms, which may help the further design and conduct of preclinical and clinical trials.

Apoptosis induction of oroxylin A in human cervical cancer HeLa cell line in vitro and in vivo

Oroxylin A is a flavonoid that is found in the roots of Scutellaria baicalensis Georgi. Here, we investigated the antitumor effect of oroxylin A in human cervical cancer HeLa cell line in vitro and in vivo. We found that after inoculated with the HeLa cells the mice treated with oroxylin A showed a significant decrease of tumor volumes and tumor weight compared with the control. Meanwhile, the growth inhibition of oroxylin A on HeLa cells were observed by MTT assay and the value of IC(50) was 19.4+/-0.7 microM after treatment for 48h. Upon our previous research, the inhibition by oroxylin A might be through apoptosis. Then apoptosis induced by oroxylin A in HeLa cells was characterized by DAPI staining and Annexin V/PI double staining, and degradation of PARP (poly-ADP-ribose polymerase) was both found in HeLa cells and tumor tissue. Next, activation of the caspase cascade for both the extrinsic and intrinsic pathways were demonstrated in vivo and in vitro, including caspase-8, -9 and -3. We also found that the expression of Bcl-2 protein decreased, which leading to an increase of the Bax/Bcl-2 ratio. Our results showed that oroxylin A exhibited strong antitumor effect in HeLa cell line and apoptosis induction involved in it.

Sensitization of ovarian cancer cells to cisplatin by genistein: the role of NF-kappaB

Background

Platinum-resistance (PR) continues to be a major problem in the management of epithelial ovarian cancer (EOC). Response to various chemotherapeutic agents is poor in patients deemed PR. Genistein, a soy isoflavone has been shown to enhance the effect of chemotherapy in prostate and pancreatic cancer cells in vitro and in vivo by reversing chemo-resistance phenotype. The goal of this study was to investigate the effects of combination therapy with genistein and cisplatin as well as other cytotoxic conventional chemotherapeutic agents in platinum-sensitive (PS) and resistant EOC cells.

Methods

The PS human ovarian cancer cell line A2780 and its PR clone C200 cells were pretreated with genistein, followed by the combination of genistein and either cisplatin, taxotere or gemcitabine. Cell survival and apoptosis was assessed by MTT and histone-DNA ELISA. Electrophoretic mobility shift assay (EMSA) was used to evaluate NF-κB DNA binding activity. Western blot analysis was performed with antibodies to Bcl-2, Bcl-xL, survivin, c-IAP and PARP.

Results

Reduction in cell viability, and corresponding induction of apoptosis was observed with genistein pretreatment followed by combination treatment with each of the drugs in both cell lines. The PS cell line was pretreated for 24 hours; in contrast, the PR cell line required 48 hours pretreatment to achieve a response. The anti-apoptotic genes c-IAP1, Bcl-2, Bcl-xL, survivin and NF-κB DNA binding activity were all found to be down-regulated in the combination groups.

Conclusion

This study convincingly demonstrated that the current strategy can be translated in a pre-clinical animal model, and thus it should stimulate future clinical trial for the treatment of drug-resistant ovarian cancer.

Biological approaches to therapy of pancreatic cancer

Pancreatic cancer is a lethal disease and notoriously difficult to treat. Only a small proportion is curative by surgical resection, whilst standard chemotherapy for patients with advanced disease has only modest effect with substantial toxicity. Clearly there is a need for the continual development of novel therapeutic agents to improve the current situation. Improvement of our understanding of the disease has generated a large number of studies on biological approaches targeting the molecular abnormalities of pancreatic cancer, including gene therapy and signal transduction inhibition, antiangiogenic and matrix metalloproteinase inhibition, oncolytic viral therapy and immunotherapy. This article provides a review of these approaches, both investigated in the laboratories and in subsequent clinical trials.

TW-37, a small-molecule inhibitor of Bcl-2, inhibits cell growth and invasion in pancreatic cancer

Bcl-2 family of proteins plays critical roles in human cancers, including pancreatic cancer, suggesting that the discovery of specific agents targeting Bcl-2 family proteins would be extremely valuable for pancreatic cancer therapy. We have previously reported the synthesis and characterization of TW-37, which seems to be a negative regulator of Bcl-2. In this investigation, we tested our hypothesis whether TW-37 could be an effective inhibitor of cell growth, invasion and angiogenesis in pancreatic cancer cells. Using multiple cellular and molecular approaches such as MTT assay, apoptosis enzyme-linked immunosorbent assay, real-time reverse transcription-polymerase chain reaction, Western blotting, electrophoretic mobility shift assay for measuring DNA binding activity of NF-kappaB, migration, invasion and angiogenesis assays, we found that TW-37, in nanomolar concentrations, inhibited cell growth in a dose- and time-dependent manner. This was accompanied by increased apoptosis and concomitant attenuation of NF-kappaB, and downregulation of NF-kappaB downstream genes such as MMP-9 and VEGF, resulting in the inhibition of pancreatic cancer cell migration, invasion and angiogenesis in vitro and caused antitumor activity in vivo. From these results, we conclude that TW-37 is a potent inhibitor of progression of pancreatic cancer cells, which could be due to attenuation of Bcl-2 cellular signaling processes. Our findings provide evidence showing that TW-37 could act as a small-molecule Bcl-2 inhibitor on well-characterized pancreatic cancer cells in culture as well as when grown as tumor in a xenograft model. We also suggest that TW-37 could be further developed as a potential therapeutic agent for the treatment of pancreatic cancer.

Multi-targeted therapy of cancer by genistein

Soy isoflavones have been identified as dietary components having an important role in reducing the incidence of breast and prostate cancers in Asian countries. Genistein, the predominant isoflavone found in soy products, has been shown to inhibit the carcinogenesis in animal models. There is a growing body of experimental evidence showing that the inhibition of human cancer cell growth by genistein is mediated via the modulation of genes that are related to the control of cell cycle and apoptosis. It has been shown that genistein inhibits the activation of NF-kappaB and Akt signaling pathways, both of which are known to maintain a homeostatic balance between cell survival and apoptosis. Moreover, genistein antagonizes estrogen- and androgen-mediated signaling pathways in the processes of carcinogenesis. Furthermore, genistein has been found to have antioxidant properties, and shown to be a potent inhibitor of angiogenesis and metastasis. Taken together, both in vivo and in vitro studies have clearly shown that genistein, one of the major soy isoflavones is a promising agent for cancer chemoprevention and further suggest that it could be an adjunct to cancer therapy by virtue of its effects on reversing radioresistance and chemoresistance. In this review, we attempt to provide evidence for these preventive and therapeutic effects of genistein in a succinct manner highlighting comprehensive state-of-the-art knowledge regarding its multi-targeted biological and molecular effects in cancer cells.

Synergy of gemcitabine and lidamycin associated with NF-kappaB downregulation in pancreatic carcinoma cells

AIM

To investigate the effects on human pancreatic cancer PANC-1 and SW1990 cells using a combination of lidamycin (LDM) and gemcitabine.

METHODS

A 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the growth inhibition of drugs in PANC-1 and SW1990 cells. The effects on apoptosis were measured by terminal uridine deoxynucleotidyl transferase dUTP nick end labeling assay and flow cytometry combined with fluorescein- isothiocyanate-Annexin V/propidium iodide staining. The activity of caspase-3 was measured with a special assay kit. The mitochondrial membrane potential was determined by confocal microscopy analyses. The level of mRNA encoding K-ras in the cells was determined by RT-PCR analysis. The expression of K-ras, NF-kappaB, and Bcl-2 was detected by Western blotting analysis.

RESULTS

There was a significant reduction in proliferation in the pancreatic cancer cell lines treated with a combination of gemcitabine and LDM. The overall growth inhibition directly correlated with apoptotic cell death. LDM potentiated the gemcitabine-induced cell killing by reducing mitochondrial membrane potential and increasing the caspase-3 activity. Notably, the K-ras mRNA level was significantly reduced with the combination of gemcitabine and LDM. The results for K-ras, NF-kappaB, and Bcl-2 proteins also showed downregulation in the combination group relative to the single-agent treatment and the untreated control.

CONCLUSION

LDM can potentiate the growth inhibition induced by gemcitabine in human pancreatic cancer cells, and the synergy may be associated with NF-kappaB downregulation.

Genistein-induced apoptosis of human breast cancer MCF-7 cells involves calpain–caspase and apoptosis signaling kinase 1–p38 mitogen-activated protein kinase activation cascades

The molecular mechanisms of genistein-induced apoptosis of human breast cancer MCF-7 cells were investigated. Genistein showed 50% cell growth inhibition at IC50=27.5+/-0.8 micromol/l in 24 h incubation under 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay conditions. Genistein is known to express both cell growth activity at nanomolar concentrations and anti-cell growth activity at micromolar concentrations. It was found that genistein at 100 micromol/l concentration effectively induced apoptosis of MCF-7 cells in 24 h. Genistein-induced apoptosis involved activation of calpain, caspase 7 and poly(ADP ribose) polymerase. Dantrolene, an inhibitor of Ca release from the endoplasmic reticulum, inhibited genistein-induced activation of calpain and caspase 7, in addition to effectively negating genistein-induced apoptosis. MCF-7 cells treated with genistein also showed increased phosphorylation of p38 mitogen-activated protein kinase, whereas no effect was observed for extracellular signal-regulating kinase 1/2. Phosphorylation of apoptosis signaling kinase 1, an upstream regulator of p38 mitogen-activated protein kinase, was also increased by genistein treatment. Genistein-induced phosphorylation of apoptosis signaling kinase 1 and p38 mitogen-activated protein kinase was diminished by the presence of dantrolene. These results suggest that genistein-induced apoptosis in MCF-7 cells is mediated through calpain-caspase 7 and apoptosis signaling kinase 1-p38 mitogen-activated protein kinase activation cascades that involve Ca release from the endoplasmic reticulum.

Mechanisms of resistance to cisplatin and carboplatin

While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.

Effects of dietary flavonoids on apoptotic pathways related to cancer chemoprevention

Epidemiological studies have described the beneficial effects of dietary polyphenols (flavonoids) on the reduction of the risk of chronic diseases, including cancer. Moreover, it has been shown that flavonoids, such as quercetin in apples, epigallocatechin-3-gallate in green tea and genistein in soya, induce apoptosis. This programmed cell death plays a critical role in physiological functions, but there is underlying dysregulation of apoptosis in numerous pathological situations such as Parkinson's disease, Alzheimer's disease and cancer. At the molecular level, flavonoids have been reported to modulate a number of key elements in cellular signal transduction pathways linked to the apoptotic process (caspases and bcl-2 genes), but that regulation and induction of apoptosis are unclear. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activities of representative flavonoids, with emphasis on their ability to control intracellular signaling cascades responsible for regulating apoptosis, a relevant target in cancer-preventive approach.

Pancreatic cancer: pathogenesis, prevention and treatment

Pancreatic cancer is the fourth leading cause of cancer death in the United States with a very low survival rate of 5 years. To better design new preventive and/or therapeutic strategies for the fight against pancreatic cancer, the knowledge of the pathogenesis of pancreatic cancer at the molecular level is very important. It has been known that the development and the progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways among which the EGFR, Akt, and NF-kappaB pathways appear to be most relevant. Therefore, the strategies targeting EGFR, Akt, NF-kappaB, and their downstream signaling could be promising for the prevention and/or treatment of pancreatic cancer. In this brief review, we will summarize the current knowledge regarding the pathogenesis, prevention, and treatment of pancreatic cancer.