Effects of phytochemicals on ionization radiation-mediated carcinogenesis and cancer therapy

The Promise of Piperine in Cancer Chemoprevention

Cancer, characterized by the unregulated growth and dissemination of malignantly transformed cells, presents a significant global health challenge. The multistage process of cancer development involves intricate biochemical and genetic alterations within target cells. Cancer chemoprevention has emerged as a vital strategy to address this complex issue to mitigate cancer's impact on healthcare systems. This approach leverages pharmacologically active agents to block, suppress, prevent, or reverse invasive cancer development. Among these agents, piperine, an active alkaloid with a wide range of therapeutic properties, including antioxidant, anti-inflammatory, and immunomodulatory effects, has garnered attention for its potential in cancer prevention and treatment. This comprehensive review explores piperine's multifaceted role in inhibiting the molecular events and signaling pathways associated with various stages of cancer development, shedding light on its promising prospects as a versatile tool in cancer chemoprevention. Furthermore, the review will also delve into how piperine enhances the effectiveness of conventional treatments such as UV-phototherapy and TRAIL-based therapy, potentially synergizing with existing therapeutic modalities to provide more robust cancer management strategies. Finally, a crucial perspective of the long-term safety and potential side effects of piperine-based therapies and the need for clinical trials is also discussed.

Protective Effect of Vaccinium myrtillus Extract on X-Ray Irradiation-Induced Retinal Toxicity via eNOS and 8-OHdG expression

Every year, hundreds of thousands of cancer patients receive radiotherapy treatment. Oxidative stress is observed in healthy tissues due to irradiation exposure. The present study is the first to address the effects of Vaccinium myrtillus (whortleberry, WB) against the effects of X-ray irradiation on retinal tissue. Twenty-four Sprague-Dawley rats were randomly allocated into 4 groups: (1) control group: rats without any treatment, (2) X-ray irradiation group: 8 Gray (Gy) RT for 2 days, (3) 100 mg WB extract + X-ray irradiation group: 8 Gy irradiation for 2 days and followed by intraperitoneal (IP) WB extract (100 mg/kg) supplementation for 10 days, (4) 200 mg WB extract + X-ray irradiation group: 8 Gy irradiation for 2 days and followed by IP WB extract (200 mg/kg) supplementation for 10 days. Eyes were enucleated on the 10th day after RT for histopathological, immunohistochemical (8-hydroxy-2'-deoxyguanosine [8-OHdG], endothelial nitric oxide synthase [eNOS]), and biochemical analyses (glutathione peroxidase [GSH], and malondialdehyde [MDA]). The GSH levels significantly decreased and MDA levels and 8-OHdG staining increased after X-ray irradiation compared to the control group. Combined X-ray irradiation + WB treatment significantly increased GSH levels and significantly decreased MDA production and 8-OHdG staining. However, eNOS staining was not affected in any of the groups. Besides, X-ray irradiation significantly increased cell losses and edematous areas. The WB significantly reversed the cellular damage in ganglion cells, inner nuclear, and outer nuclear layers in quantitative analyses. The X-ray irradiation caused significant retinal impairment, and additional WB therapy provided protective effects against radiation-induced retinopathy. These results may suggest WB extract as an adjuvant therapy to reverse retinal impairments after X-ray irradiation.

Biosynthesis of anticancer phytochemical compounds and their chemistry

Cancer is a severe health issue, and cancer cases are rising yearly. New anticancer drugs have been developed as our understanding of the molecular mechanisms behind diverse solid tumors, and metastatic malignancies have increased. Plant-derived phytochemical compounds target different oncogenes, tumor suppressor genes, protein channels, immune cells, protein channels, and pumps, which have attracted much attention for treating cancer in preclinical studies. Despite the anticancer capabilities of these phytochemical compounds, systemic toxicity, medication resistance, and limited absorption remain more significant obstacles in clinical trials. Therefore, drug combinations of new phytochemical compounds, phytonanomedicine, semi-synthetic, and synthetic analogs should be considered to supplement the existing cancer therapies. It is also crucial to consider different strategies for increased production of phytochemical bioactive substances. The primary goal of this review is to highlight several bioactive anticancer phytochemical compounds found in plants, preclinical research, their synthetic and semi-synthetic analogs, and clinical trials. Additionally, biotechnological and metabolic engineering strategies are explored to enhance the production of bioactive phytochemical compounds. Ligands and their interactions with their putative targets are also explored through molecular docking studies. Therefore, emphasis is given to gathering comprehensive data regarding modern biotechnology, metabolic engineering, molecular biology, and in silico tools.

Pterostilbene regulates cell proliferation and apoptosis in non-small-cell lung cancer via targeting COX-2

Non-small-cell lung cancer (NSCLC), occupying a great proportion of lung cancer, threatens the health of patients, and the cyclooxygenase-2 (COX-2) expression is found to be upregulated in lung cancer. Pterostilbene (PTE) is perceived as a novel method for clinical therapy due to its high performance. However, the mechanism underlying and the interaction between PTE and COX-2 remain vague. We simulated radiation circumstances and transfected cells with the interference of PTE and COX-2. Our results showed that radiation or PTE treatment alone restrained cell proliferation and viability while stimulating cell apoptosis, and the above properties were strengthened when the two were in combination. The COX-2 expression was promoted by radiation but was reduced by PTE. PTE reversed the effects of radiation on the COX-2 expression. COX-2 knockdown suppressed COX-2 expression and proliferation and enhanced apoptosis of cells suffering radiation, while COX-2 overexpression reversed the inhibition of PTE. Our study suggested PTE regulated NSCLC cell proliferation and apoptosis via targeting COX-2, which might shed a light on cancer therapy.

Silibinin Radiosensitizes EGF Receptor-knockdown Prostate Cancer Cells by Attenuating DNA Repair Pathways

Emergence of radioresistance in prostate cancer (PCa) cells is a major obstacle in cancer therapy and contributes to the relapse of the disease. EGF receptor (EGFR) signaling plays an important role in the development of radioresistance. Herein, we have assessed the modulatory effects of silibinin on radiation-induced resistance via DNA repair pathways in EGFR-knockdown DU145 cells. shRNA-based silencing of EGFR was done in radioresistant human PCa DU145 cells and effects of ionizing radiation (IR) and silibinin were assessed using clonogenic and trypan blue assays. Furthermore, radiosensitizing effects of silibinin on PCa in context with EGFR were analyzed using flow cytometry, comet assay, and immunoblotting. Silibinin decreased the colony formation ability with an increased death of DU145 cells exposed to IR (5 Gray), with a concomitant decrease in Rad51 protein expression. Silibinin (25 μM) augmented the IR-induced cytotoxic effect in EGFR-knockdown PCa cells, along with induction of G2/M phase cell cycle arrest. Further, we studied homologous recombination (HR) and non-homologous end joining (NHEJ) pathways in silibinin-induced DNA double-strand breaks in EGFR-knockdown DU145 cells. Silibinin down-regulated the expression of Rad51 and DNA-dependent protein kinase proteins without any considerable effect on Ku70 and Ku80 in IR-exposed EGFR-knockdown PCa cells. The pro-survival signaling proteins, phospho-extracellular signal-regulated kinases (ERK)1/2, phospho-Akt and phospho-STAT3 were decreased by silibinin in EGFR-deficient PCa cells. These findings suggest a novel mechanism of silibinin-induced radiosensitization of PCa cells by targeting DNA repair pathways, HR and NHEJ, and suppressing the pro-survival signaling pathways, ERK1/2, Akt and STAT3, in EGFR-knockdown PCa cells.

Systematic Review of Gossypol/AT-101 in Cancer Clinical Trials

The potential of gossypol and of its R-(−)-enantiomer (R-(−)-gossypol acetic acid, AT-101), has been evaluated for treatment of cancer as an independent agent and in combination with standard chemo-radiation-therapies, respectively. This review assesses the evidence for safety and clinical effectiveness of oral gossypol/AT-101 in treating various types of cancer. The databases PubMed, MEDLINE, Cochrane, and ClinicalTrials.gov were examined. Phase I and II trials as well as single arm and randomized trials were included in this review. Results were screened to determine if they met inclusion criteria and then summarized using a narrative approach. A total of 17 trials involving 759 patients met the inclusion criteria. Overall, orally applied gossypol/AT-101 at low doses (30 mg daily or lower) was determined as well tolerable either as monotherapy or in combination with chemo-radiation. Adverse events should be strictly monitored and were successfully managed by dose-reduction or treating symptoms. There are four randomized trials, two performed in patients with advanced non-small cell lung cancer, one in subjects with head and neck cancer, and one in patients with metastatic castration-resistant prostate cancer. Thereby, standard chemotherapy (either docetaxel (two trials) or docetaxel plus cisplatin or docetaxel plus prednisone) was tested with and without AT-101. Within these trials, a potential benefit was observed in high-risk patients or in some patients with prolongation in progression-free survival or in overall survival. Strikingly, the most recent clinical trial combined low dose AT-101 with docetaxel, fluorouracil, and radiation, achieving complete responses in 11 of 13 patients with gastroesophageal carcinoma (median duration of 12 months) and a median progression-free survival of 52 months. The promising results shown in subsets of patients supports the need of further specification of AT-101 sensitive cancers as well as for the establishment of effective AT-101-based therapy. In addition, the lowest recommended dose of gossypol and its precise toxicity profile need to be confirmed in further studies. Randomized placebo-controlled trials should be performed to validate these data in large cohorts.

Phytochemicals: Potential Therapeutic Modulators of Radiation Induced Signaling Pathways

Ionizing radiation results in extensive damage to biological systems. The massive amount of ionizing radiation from nuclear accidents, radiation therapy (RT), space exploration, and the nuclear battlefield leads to damage to biological systems. Radiation injuries, such as inflammation, fibrosis, and atrophy, are characterized by genomic instability, apoptosis, necrosis, and oncogenic transformation, mediated by the activation or inhibition of specific signaling pathways. Exposure of tumors or normal cells to different doses of ionizing radiation could lead to the generation of free radical species, which can release signal mediators and lead to harmful effects. Although previous FDA-approved agents effectively mitigate radiation-associated toxicities, their use is limited due to their high cellular toxicities. Preclinical and clinical findings reveal that phytochemicals derived from plants that exhibit potent antioxidant activities efficiently target several signaling pathways. This review examined the prospective roles played by some phytochemicals in altering signal pathways associated with radiation response.

Effects of radiation and role of plants in radioprotection: A critical review

Radiation can be lethal at high doses, whereas controlled doses are useful in medical applications. Other applications include power generation, agriculture sterilization, nuclear weapons, and archeology. Radiation damages genetic material, which is reflected in genotoxicity and can cause hereditary damage. In the medical field, it is essential to avoid the harmful effects of radiation. Radiation countermeasures and the need for radioprotective agents have been explored in recent years. Considering plants that evolve in radiative conditions, their ability to protect organisms against radiation has been studied and demonstrated. Crude extracts, fractioned extracts, isolated phytocompounds, and plant polysaccharides from various plants have been used in radioprotection studies, and their efficiency has been proven in various in vitro and in vivo experimental models. It is important to identify the mechanism of action to develop a potent plant-based radioprotective agent. To identify this protective mechanism, it is necessary to understand the damage caused by radiation in biological systems. This review intends to discuss the effects of ionizing radiation on biological systems and evaluate plant-based radioprotectants that have tested thus far as well as their mechanism of action in protecting against the toxic effects of radiation. From the review, the mechanism of radioprotection exhibited by the plant-based products could be understood. Meanwhile, we strongly suggest that the potential products identified so far should undergo clinical trials for critically evaluating their effects and for developing an ideal and compatible radioprotectant with no side-effects.

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

Centipedegrass extract enhances radiosensitivity in melanoma cells by inducing G2/M cell cycle phase arrest

Melanoma is aggressive, highly metastatic, and potentially fatal. In the case of patients with advanced melanoma, it is difficult to expect a good prognosis, since this cancer has low sensitivity to chemotherapy and radiation therapy. The use of natural ingredients may enhance existing therapies. Centipedegrass extract (CGE) which contains phenolic structures and C-glycosyl flavones, has been shown to have anti-inflammatory effects and anti-cancer effects. The purpose of this study was to evaluate the radio sensitizing effects of CGE in combination with ionizing radiation (IR). Two melanoma cell lines were exposed to IR after treatment with CGE at concentrations that were not toxic alone. The effects of CGE + IR on cell survival, cell cycle, and apoptotic cell death were examined using MTT and Muse® Cell Analyzer, and fluorescence microscopy. Molecular signaling mechanisms were explored by western blots. Our findings showed that co-treatment of CGE + IR reduced the survival of melanoma cells more than IR alone. Also, cell cycle arrest in CGE-treated cells was enhanced and these cells became more radiosensitive. CGE + IR increased apoptotic cell death more than IR alone. Western blot results showed that the effect of CGE + IR involved MAPKs (ERK1/2, p38, and JNK) pathway. Our study suggests that CGE + IR treatment enhanced radio-sensitization and cell death of melanoma cells via cell cycle arrest and the MAPKs pathway.

Delphinidin enhances radio-therapeutic effects via autophagy induction and JNK/MAPK pathway activation in non-small cell lung cancer

Delphinidin is a major anthocyanidin compound found in various vegetables and fruits. It has anti-oxidant, anti-inflammatory, and various other biological activities. In this study we demonstrated the anti-cancer activity of delphinidin, which was related to autophagy, in radiation-exposed non-small cell lung cancer (NSCLC). Radiosensitising effects were assessed in vitro by treating cells with a sub-cytotoxic dose of delphinidin (5 µM) before exposure to γ-ionising radiation (IR). We found that treatment with delphinidin or IR induced NSCLC cell death in vitro; however the combination of delphinidin pre-treatment and IR was more effective than either agent alone, yielding a radiation enhancement ratio of 1.54 at the 50% lethal dose. Moreover, combined treatment with delphinidin and IR, enhanced apoptotic cell death, suppressed the mTOR pathway, and activated the JNK/MAPK pathway. Delphinidin inhibited the phosphorylation of PI3K, AKT, and mTOR, and increased the expression of autophagy-induced cell death associated-protein in radiation-exposed NSCLC cells. In addition, JNK phosphorylation was upregulated by delphinidin pre-treatment in radiation-exposed NSCLC cells. Collectively, these results show that delphinidin acts as a radiation-sensitizing agent through autophagy induction and JNK/MAPK pathway activation, thus enhancing apoptotic cell death in NSCLC cells.

Phytoestrogen genistein hinders ovarian oxidative damage and apoptotic cell death-induced by ionizing radiation: co-operative role of ER-β, TGF-β, and FOXL-2

Radiotherapy is a well-known cause of premature ovarian failure (POF). Therefore, we investigated the molecular influence of genistein (GEN) on the ovarian reserve of rats exposed to ϒ-radiation. Female Sprague Dawley rats were exposed to a 3.2 Gy γ-radiation to induce POF and/or treated with either GEN (5 mg/kg, i.p.) or Ethinyl estradiol (E2; 0.1 mg/kg, s.c.), once daily for 10 days. GEN was able to conserve primordial follicles stock and population of growing follicles accompanied with reduction in atretic follicles. GEN restored the circulating estradiol and anti-Müllerian hormone levels which were diminished after irradiation. GEN has potent antioxidant activity against radiation-mediated oxidative stress through upregulating endogenous glutathione levels and glutathione peroxidase activity. Mechanistically, GEN inhibited the intrinsic pathway of apoptosis by repressing Bax expression and augmenting Bcl-2 expression resulted in reduced Bax/Bcl-2 ratio with subsequent reduction in cytochrome c and caspase 3 expression. These promising effects of GEN are associated with improving granulosa cells proliferation. On the molecular basis, GEN reversed ovarian apoptosis through up-regulation of ER-β and FOXL-2 with downregulation of TGF-β expression, therefore inhibiting transition of primordial follicles to more growing follicles. GEN may constitute a novel therapeutic modality for safeguarding ovarian function of females' cancer survivors.

In Vitro Anticancer and Radiosensitizing Activities of Phlorethols from the Brown Alga Costaria costata

The anticancer and radiosensitizing effects of high-molecular-weight phlorethols CcPh (Mw = 2520 Da) isolated from the brown algae of Costaria costata on human colorectal carcinoma HCT 116 and HT-29 cells were investigated. Phlorethols CcPh possessed cytotoxic activity against HT-29 (IC50 = 92 μg/mL) and HCT 116 (IC50 = 94 μg/mL) cells. CcPh at non-toxic concentrations inhibited the colony formation in colon cancer cells and significantly enhanced their sensitivity to low non-toxic X-ray irradiation. The combinatory effect of radiation and CcPh was synergistic (Combination index < 0.7). Algal phlorethols might be prospective candidates as radiosensitizers to improve the scheme of radiotherapy.

Biocurcumin as Radiosensitiser for Cervical Cancer Study (BRACES): A Double-Blind Randomised Placebo-Controlled Trial

Cervical cancer is a leading cause of death among women worldwide, particularly in Indonesia. The main treatment of advanced-stage cervical cancer is radiation; however, the outcomes do not meet the required expectations. [1,7-Bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5dione] has been reported in several studies for its potency in cancer therapy. This study aims to investigate the clinical and molecular [(malondialdehyde (MDA) and NF-κB levels] effects, apoptotic index, and safety of Biocurcumin (BCM-95) as a radiosensitiser in cervical cancer. In this double-blind placebo randomised-controlled trial, we randomised 121 patients into 2 groups (BCM-95 or placebo). MDA and their NF-κB levels and apoptotic index were measured before and after administering 24 Gy of radiation. MDA was identified using Wills' method, whereas NF-κB was identified via ELISA. The apoptotic index was identified using TUNEL and DAPI staining. The clinical response was classified based on the RECIST. MDA levels before radiation were similar between both groups in per protocol and intention-to-treat (ITT) analyses (p = 0.53 and p = 0.16, respectively). After radiation, MDA levels increased in both groups with no significant differences in per protocol and ITT analyses (p = 0.52 and p = 0.18, respectively). NF-κB levels before radiation were similar between the two groups in per protocol and ITT analyses (p = 0.92 and p = 0.98, respectively). After radiation, the BCM-95 group showed an increase in the NF-κB levels compared with the placebo group in per protocol analysis but not in ITT analysis (p = 0.018 and p = 0.42, respectively). The BCM-95 group had a higher apoptotic index before radiation in per protocol analysis but not in ITT analysis (p = 0.01 and p = 0.61, respectively). After radiation, the apoptotic index remained higher in the BCM-95 group in per protocol analysis but not in ITT analysis (p = 0.04 and p = 0.91, respectively). There was no significant difference in complete response between the groups (per protocol, p = 0.61; ITT analysis, p = 0.90). Although BCM-95 can regulate ROS, NF-κB, and apoptosis in human cervical cancer, it is not significant. Therefore, BCM-95 does not improve clinical response to radiation treatment.

Comparison between tumors in plants and human beings: Mechanisms of tumor development and therapy with secondary plant metabolites

BACKGROUND

Human tumors are still a major threat to human health and plant tumors negatively affect agricultural yields. Both areas of research are developing largely independent of each other. Treatment of both plant and human tumors remains unsatisfactory and novel therapy options are urgently needed.

HYPOTHESIS

The concept of this paper is to compare cellular and molecular mechanisms of tumor development in plants and human beings and to explore possibilities to develop novel treatment strategies based on bioactive secondary plant metabolites. The interdisciplinary discourse may unravel commonalities and differences in the biology of plant and human tumors as basis for rational drug development.

RESULTS

Plant tumors and galls develop upon infection by bacteria (e.g. Agrobacterium tumefaciens and A. vitis, which harbor oncogenic T-DNA) and by insects (e.g. gall wasps, aphids). Plant tumors are benign, i.e. they usually do not ultimately kill their host, but they can lead to considerable economic damage due to reduced crop yields of cultivated plants. Human tumors develop by biological carcinogenesis (i.e. viruses and other infectious agents), chemical carcinogenesis (anthropogenic and non-anthropogenic environmental toxic xenobiotics) and physical carcinogenesis (radioactivity, UV-radiation). The majority of human tumors are malignant with lethal outcome. Although treatments for both plant and human tumors are available (antibiotics and apathogenic bacterial strains for plant tumors, cytostatic drugs for human tumors), treatment successes are non-satisfactory, because of drug resistance and the severe adverse side effects. In human beings, attacks by microbes are repelled by cellular immunity (i.e. innate and acquired immune systems). Plants instead display chemical defense mechanisms, whereby constitutively expressed phytoanticipin compounds compare to the innate human immune system, the acquired human immune system compares to phytoalexins, which are induced by appropriate biotic or abiotic stressors. Some chemical weapons of this armory of secondary metabolites are also active against plant galls. There is a mutual co-evolution between plant defense and animals/human beings, which was sometimes referred to as animal plant warfare. As a consequence, hepatic phase I-III metabolization and excretion developed in animals and human beings to detoxify harmful phytochemicals. On the other hand, plants invented "pro-drugs" during evolution, which are activated and toxified in animals by this hepatic biotransformation system. Recent efforts focus on phytochemicals that specifically target tumor-related mechanisms and proteins, e.g. angiogenic or metastatic inhibitors, stimulators of the immune system to improve anti-tumor immunity, specific cell death or cancer stem cell inhibitors, inhibitors of DNA damage and epigenomic deregulation, specific inhibitors of driver genes of carcinogenesis (e.g. oncogenes), inhibitors of multidrug resistance (i.e. ABC transporter efflux inhibitors), secondary metabolites against plant tumors.

CONCLUSION

The exploitation of bioactive secondary metabolites to treat plant or human tumors bears a tremendous therapeutic potential. Although there are fundamental differences between human and plant tumors, either isolated phytochemicals and their (semi)synthetic derivatives or chemically defined and standardized plant extracts may offer new therapy options to decrease human tumor incidence and mortality as well as to increase agricultural yields by fighting crown galls.

Radiosensitizing Potential of Curcumin in Different Cancer Models

Over the past decades, studies of phytochemicals as modifiers of radiotherapeutic efficacy have become increasingly popular to improve the treatment outcome of human malignancies. In the current comprehensive review article, radiosensitizing effects of curcumin, a yellow-colored polyphenolic constituent of turmeric, in various preclinical cancer models, both In Vitro and In Vivo, are presented. Attenuation of radioadaptation and augmentation of irradiation-induced cancer cell killing are achieved through multifaceted action of curcumin on suppression of prosurvival and antiapoptotic factors. Most importantly, curcumin can block radiation-triggered NF-κB signaling pathway and downregulate downstream effector proteins, thereby conferring potentiation of radioresponses. Based on the elucidated molecular mechanisms but also due to its safety profile and low cost, curcumin might be considered a promising adjuvant agent to enhance radiotherapeutic efficacy in the treatment of various cancer types formed in different human organ systems. Further efforts to translate the current preclinical knowledge to the real application of curcumin in combinatorial radiotherapeutic strategies in clinical settings are necessary.AbbreviationsAKTprotein kinase BARMSalveolar rhabdomyosarcomaATMataxia telangiectasia mutatedBaxBcl-2-associated X proteinBcl-2B-cell lymphoma 2CDC2cyclin-dependent kinase 2Bcl-xLB-cell lymphoma-extra largec-FLIPcellular FLICE-like inhibitory proteinCDDPcisplatinCOX-2cyclooxygenase-2cyt ccytochrome cDNA-PKcsDNA-dependent protein kinaseEGFRepidermal growth factor receptorEMTepithelial-mesenchymal transitionERKextracellular signal-regulated kinaseESEwing`s sarcomaETS2erythroblastosis virus transcription factor 2GBMglioblastoma multiformeHCChepatocellular carcinomaHNSCChead and neck squamous cell carcinomaIAPinhibitor of apoptosis proteinIκBαinhibitor of κB alphaIKKinhibitor of κB kinaseIRionizing radiationlncRNAlong non-coding RNAlucluciferaseMcl-1myeloid cell leukemia-1MDR1multidrug resistance protein 1miRmicroRNAMMP-9matrix metalloproteinase-9mTORmammalian target of rapamycinNBneuroblastomaNF-κBnuclear factor-κBNPCnasopharyngeal carcinomaNSCLCnon-small cell lung cancerOSCCoral squamous cell carcinomaPARPpoly-(ADP-ribose)-polymerasepH2AXphosphorylated histone 2AX-immunoreactivePI3Kphosphatidylinositol 3-kinasePrp4KPre-mRNA processing factor 4 kinaseRCCrenal cell carcinomaROSreactive oxygen speciesSCCsquamous cell carcinomaSLNsolid lipid nanoparticleSOD2superoxide dismutase 2TERTtelomerase reverse transcriptaseTNF-αtumor necrosis factor-αTxnRd1thioredoxin reductase-1VEGFvascular endothelial growth factorXIAPX-linked inhibitor of apoptosis proteinΔΨmmitochondrial membrane potential.

Effects of Polar Steroids from the Starfish Patiria (=Asterina) pectinifera in Combination with X-Ray Radiation on Colony Formation and Apoptosis Induction of Human Colorectal Carcinoma Cells

Despite significant advances in the understanding, prevention, and treatment of cancer, the disease continues to affect millions of people worldwide. Chemoradiation therapy is a rational approach that has already proven beneficial for several malignancies. However, the existence of toxicity to normal tissue is a serious limitation of this treatment modality. The aim of the present study is to investigate the ability of polar steroids from starfish Patiria (=Asterina) pectinifera to enhance the efficacy of radiation therapy in colorectal carcinoma cells. The cytotoxic activity of polar steroids and X-ray radiation against DLD-1, HCT 116, and HT-29 cells was determined by an MTS assay. The effect of compounds, X-ray, and their combination on colony formation was studied using the soft agar method. The molecular mechanism of the radiosensitizing activity of asterosaponin P₁ was elucidated by western blotting and the DNA comet assay. Polar steroids inhibited colony formation in the tested cells, and to a greater extent in HT-29 cells. Asterosaponin P₁ enhanced the efficacy of radiation and, as a result, reduced the number and size of the colonies of colorectal cancer cells. The radiosensitizing activity of asterosaponin P₁ was realized by apoptosis induction through the regulation of anti- and pro-apoptotic protein expression followed by caspase activation and DNA degradation.

Prevention from radiation damage by natural products

BACKGROUND

Radiotherapy is a mainstay of cancer treatment since decades. Ionizing radiation (IR) is used for destruction of cancer cells and shrinkage of tumors. However, the increase of radioresistance in cancer cells and radiation toxicity to normal tissues are severe concerns. The exposure to radiation generates intracellular reactive oxygen species (ROS), which leads to DNA damage by lipid peroxidation, removal of thiol groups from cellular and membrane proteins, strand breaks and base alterations.

HYPOTHESIS

Plants have to deal with radiation-induced damage (UV-light of sun, other natural radiation sources). Therefore, it is worth speculating that radioprotective mechanisms have evolved during evolution of life. We hypothesize that natural products from plants may also protect from radiation damage caused as adverse side effects of cancer radiotherapy.

METHODS

The basis of this systematic review, we searched the relevant literature in the PubMed database.

RESULTS

Flavonoids, such as genistein, epigallocatechin-3-gallate, epicatechin, apigenin and silibinin mainly act as antioxidant, free radical scavenging and anti-inflammatory compounds, thus, providing cytoprotection in addition to downregulation of several pro-inflammatory cytokines. Comparable effects have been found in phenylpropanoids, especially caffeic acid phenylethylester, curcumin, thymol and zingerone. Besides, resveratrol and quercetin are the most important cytoprotective polyphenols. Their radioprotective effects are mediated by a wide range of mechanisms mainly leading to direct or indirect reduction of cellular stress. Ascorbic acid is broadly used as antioxidant, but it has also shown activity in reducing cellular damage after irradiation mainly due to its antioxidant capabilities. The metal ion chelator, gallic acid, represents another natural product attenuating cellular damage caused by radiation.

CONCLUSIONS

Some secondary metabolites from plants reveal radioprotective features against cellular damage caused by irradiation. These results warrant further analysis to develop phytochemicals as radioprotectors for clinical use.

A combination of resveratrol and 3,3'-diindolylmethane, a potent radioprotector

PURPOSE

Exposure to ionizing radiation causes damage to the genomic integrity and stability of the cell. Though a large number of molecules have been studied for their radioprotective capability, no single agent is available today that meets all the requirements of a good radiprotector. In this study, we have investigated a combination of Resveratrol (RSV) and 3,3'-Diindolyl methane (DIM) for its efficacy for radioprotection. It is our hypothesis that this combination that possesses less toxicity than synthetic compounds, free radical scavenging potential, and the capacity to interfere with the several of the signaling cascades that trigger damage to cell by ionizing radiation may possess good radioprotective capability.

MATERIALS AND METHODS

Mice were pre-treated with a combination of RSV and DIM and the 30-day mortality assay, endogenous antioxidant levels in intestinal mucosa, metaphase chromosomal aberrations, and micronuclei formation were assessed after exposed to ionizing radiation.

RESULTS

The dose modifying factor (DRF) obtained for RSV, DIM, and the combination is 1.15, 1.17, and 1.3, respectively. Pre-treatment of mice with the combination results in significant (***p = .001) protection of the endogenous antioxidant levels, chromosomal aberrations, micronuclei formation, after exposure to ionizing radiation.

CONCLUSIONS

Our findings suggest that pre-treatment with the combination of RSV and DIM protects effectively from the ionizing radiation-induced damage at the molecular, cellular, and tissue levels by counteracting both the direct and indirect effects.

Caffeic acid phenethyl ester down-regulates claudin-2 expression at the transcriptional and post-translational levels and enhances chemosensitivity to doxorubicin in lung adenocarcinoma A549 cells

Claudin-2 is highly expressed in human lung adenocarcinoma cells and involved in the promotion of proliferation. Here, we searched for a compound, which can decrease claudin-2 expression using lung adenocarcinoma A549 cells. In the screening using compounds included in royal jelly and propolis, the protein level of claudin-2 was dose-dependently decreased by caffeic acid phenethyl ester (CAPE), whereas the mRNA level and promoter activity were only decreased by 50 μM CAPE. These results suggest that CAPE down-regulates claudin-2 expression mediated by two different mechanisms. CAPE (50 μM) decreased the level of p-NF-κB, whereas it increased that of IκB. The CAPE-induced decrease in promoter activity of claudin-2 was blocked by the mutation in an NF-κB-binding site. The inhibition of NF-κB may be involved in the decrease in mRNA level of claudin-2. The CAPE (10 μM)-induced decrease in claudin-2 expression was inhibited by chloroquine, a lysosomal inhibitor. CAPE increased the expression and activity of protein phosphatase (PP) 1 and 2A. The CAPE-induced decrease in claudin-2 expression was blocked by cantharidin, a potent PPs inhibitor. The cell proliferation was suppressed by CAPE, which was partially rescued by ectopic expression of claudin-2. In addition, the toxicity and accumulation of doxorubicin in 3D spheroid cells were enhanced by CAPE, which was inhibited by ectopic expression of claudin-2. Taken together, CAPE down-regulates claudin-2 expression at the transcriptional and post-translational levels, and enhances sensitivity of cells to doxorubicin in 3D culture conditions. CAPE may be a useful adjunctive compound in the treatment of lung adenocarcinoma.

Fractionation enhances acute oligodendrocyte progenitor cell radiation sensitivity and leads to long term depletion

Ionizing radiation (IR) is commonly used to treat central nervous system (CNS) cancers and metastases. While IR promotes remission, frequent side effects including impaired cognition and white matter loss occur following treatment. Fractionation is used to minimize these CNS late side effects, as it reduces IR effects in differentiated normal tissue, but not rapidly proliferating normal or tumor tissue. However, side effects occur even with the use of fractionated paradigms. Oligodendrocyte progenitor cells (OPCs) are a proliferative population within the CNS affected by radiation. We hypothesized that fractionated radiation would lead to OPC loss, which could contribute to the delayed white matter loss seen after radiation exposure. We found that fractionated IR induced a greater early loss of OPCs than an equivalent single dose exposure. Furthermore, OPC recovery was impaired following fractionated IR. Finally, reduced OPC differentiation and mature oligodendrocyte numbers occurred in single dose and fractionated IR paradigms. This work demonstrates that fractionation does not spare normal brain tissue and, importantly, highlights the sensitivity of OPCs to fractionated IR, suggesting that fractionated schedules may promote white matter dysfunction, a point that should be considered in radiotherapy.

Effects of traditional oriental medicines as anti-cytotoxic agents in radiotherapy

The primary goal of radiotherapy in oncology is to enhance the efficacy of tumor cell death while decreasing damage to surrounding normal cells. Positive therapeutic outcomes may be accomplished by improved targeting, precisely targeting tumor cells or protecting normal cells against radiation-induced damage. The potential for antioxidants to decrease normal tissue damage induced by radiation has been investigated in animal models for a number of decades. In attempts for radioprotection, certain synthetic chemicals are suggested as antioxidants and normal tissue protectors against radiation-induced damage, but they have exhibited limitations in pharmacological application due to undesirable effects and high toxicities at clinical doses. The present review focuses on the radioprotective efficacy of traditional oriental medicines with the advantage of low toxicity at pharmacological doses and how such treatments may influence various harmful effects induced by radiation in vitro and in vivo. In addition, medicinal plants and their active constituents with biological activities that may be associated with alleviation of radiation-induced damage through antioxidant, anti-inflammatory, wound healing and immunostimulatory properties are discussed.

ATM/CHK/p53 Pathway Dependent Chemopreventive and Therapeutic Activity on Lung Cancer by Pterostilbene

Among the many stilbenoids found in a variety of berries, resveratrol and pterostilbene are of particular interest given their potential for use in cancer therapeutics and prevention. We purified four stilbenoids from R. undulatum and found that pterostilbene inhibits cancer cell proliferation more efficiently than rhapontigenin, piceatannol and resveratrol. To investigate the underlying mechanism of this superior action of pterostilbene on cancer cells, we utilized a reverse-phase protein array followed by bioinformatic analysis and found that the ATM/CHK pathway is modified by pterostilbene in a lung cancer cell line. Given that ATM/CHK signaling requires p53 for its biological effects, we hypothesized that p53 is required for the anticancer effect of pterostilbene. To test this hypothesis, we used two molecularly defined precancerous human bronchial epithelial cell lines, HBECR and HBECR/p53i, with normal p53 and suppressed p53 expression, respectively, to represent premalignant states of squamous lung carcinogenesis. Pterostilbene inhibited the cell cycle more efficiently in HBECR cells compared to HBECR/p53i cells, suggesting that the presence of p53 is required for the action of pterostilbene. Pterostilbene also activated ATM and CHK1/2, which are upstream of p53, in both cell lines, though pterostilbene-induced senescence was dependent on the presence of p53. Finally, pterostilbene more effectively inhibited p53-dependent cell proliferation compared to the other three stilbenoids. These results strongly support the potential chemopreventive effect of pterostilbene on p53-positive cells during early carcinogenesis.

Resveratrol affects DNA damage induced by ionizing radiation in human lymphocytes in vitro

Resveratrol (3,4',5-trihydroxystilbene; RSV) acts on cancer cells in several ways, inducing cell cycle delay and apoptotic death, and enhancing ionizing radiation (IR)-mediated responses. However, fewer studies have examined RSV effects on normal cells. We have treated human lymphocytes in vitro with RSV, either alone or combined with IR, to evaluate its potential use as a radioprotector. We measured the effects of RSV on induction of DNA damage, repair kinetics, and modulation of histone deacetylase activity.

The human HSP70 family of chaperones: where do we stand?

The 70-kDa heat shock protein (HSP70) family of molecular chaperones represents one of the most ubiquitous classes of chaperones and is highly conserved in all organisms. Members of the HSP70 family control all aspects of cellular proteostasis such as nascent protein chain folding, protein import into organelles, recovering of proteins from aggregation, and assembly of multi-protein complexes. These chaperones augment organismal survival and longevity in the face of proteotoxic stress by enhancing cell viability and facilitating protein damage repair. Extracellular HSP70s have a number of cytoprotective and immunomodulatory functions, the latter either in the context of facilitating the cross-presentation of immunogenic peptides via major histocompatibility complex (MHC) antigens or in the context of acting as "chaperokines" or stimulators of innate immune responses. Studies have linked the expression of HSP70s to several types of carcinoma, with Hsp70 expression being associated with therapeutic resistance, metastasis, and poor clinical outcome. In malignantly transformed cells, HSP70s protect cells from the proteotoxic stress associated with abnormally rapid proliferation, suppress cellular senescence, and confer resistance to stress-induced apoptosis including protection against cytostatic drugs and radiation therapy. All of the cellular activities of HSP70s depend on their adenosine-5'-triphosphate (ATP)-regulated ability to interact with exposed hydrophobic surfaces of proteins. ATP hydrolysis and adenosine diphosphate (ADP)/ATP exchange are key events for substrate binding and Hsp70 release during folding of nascent polypeptides. Several proteins that bind to distinct subdomains of Hsp70 and consequently modulate the activity of the chaperone have been identified as HSP70 co-chaperones. This review focuses on the regulation, function, and relevance of the molecular Hsp70 chaperone machinery to disease and its potential as a therapeutic target.

Caffeic Acid Phenethyl Ester Increases Radiosensitivity of Estrogen Receptor-Positive and -Negative Breast Cancer Cells by Prolonging Radiation-Induced DNA Damage

Purpose

Breast cancer is an important cause of death among women. The development of radioresistance in breast cancer leads to recurrence after radiotherapy. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound of honeybee propolis, is known to have anticancer properties. In this study, we examined whether CAPE enhanced the radiation sensitivity of MDA-MB-231 (estrogen receptor-negative) and T47D (estrogen receptor-positive) cell lines.

Methods

The cytotoxic effect of CAPE on MDA-MB-231 and T47D breast cancer cells was evaluated by performing an 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. To assess clonogenic ability, MDA-MB-231 and T47D cells were treated with CAPE (1 µM) for 72 hours before irradiation, and then, a colony assay was performed. A comet assay was used to determine the number of DNA strand breaks at four different times.

Results

CAPE decreased the viability of both cell lines in a dose- and time-dependent manner. In the clonogenic assay, pretreatment of cells with CAPE before irradiation significantly reduced the surviving fraction of MDA-MB-231 cells at doses of 6 and 8 Gy. A reduction in the surviving fraction of T47D cells was observed relative to MDA-MB-231 at lower doses of radiation. Additionally, CAPE maintained radiation-induced DNA damage in T47D cells for a longer period than in MDA-MB-231 cells.

Conclusion

Our results indicate that CAPE impairs DNA damage repair immediately after irradiation. The induction of radiosensitivity by CAPE in radioresistant breast cancer cells may be caused by prolonged DNA damage.

Ellagic Acid and Resveratrol Prevent the Development of Cisplatin Resistance in the Epithelial Ovarian Cancer Cell Line A2780

Purpose. Several studies have shown that natural compounds like resveratrol or ellagic acid have anticancer and antioxidant properties and can stimulate apoptosis in many cancer cell lines. The aim of this study was to elucidate if resveratrol or ellagic acid, respectively, could improve the efficacy of cisplatin in ovarian cancer. Methods. As a cellular resistance model, the epithelial ovarian cancer cell line A2780 and its cisplatin-resistant subclone A2780CisR were used. A2780CisR was obtained by intermittent treatment of A2780 with cisplatin for 26 weekly cycles and showed a 4-6-fold increased resistance towards cisplatin compared to A2780. Results. Pretreatment with resveratrol or ellagic acid 48 h prior to treatment with cisplatin showed a moderate enhancement of cisplatin cytotoxicity in A2780CisR cells (shift factors were 1.6 for ellagic acid and 2.5 for resveratrol). However, intermittent treatment of A2780 with cisplatin for 26 weekly cycles in permanent presence of resveratrol or ellagic acid, respectively, completely prevented the development of cisplatin resistance. The generated cell lines named A2780Resv and A2780Ellag displayed functional characteristics (migration, proliferation, apoptosis, activation of ErbB3, ROS generation) similar to the parental cell line A2780. Conclusion. In conclusion, weekly intermittent treatment cycles of cisplatin-sensitive ovarian cancer cells with cisplatin retain cisplatin chemosensitivity in permanent presence of ellagic acid or resveratrol, respectively, whereas clinically relevant cisplatin chemoresistance develops in the absence of ellagic acid or resveratrol. Use of natural phenolic compounds may thus be a promising approach to prevent cisplatin resistance in ovarian cancer.

Effects of resveratrol and methoxyamine on the radiosensitivity of iododeoxyuridine in U87MG glioblastoma cell line

The purpose of this study was to evaluate the combination effect of resveratrol and methoxyamine on radiosensitivity of iododeoxyuridine in spheroid culture of U87MG glioblastoma cell line using colony formation and alkaline comet assays. Spheroids on day-20 with 350 µm diameters were treated with 20 µM resveratrol and/or 6 mM methoxyamine and/or 1 µM iododeoxyuridine for one volume doubling time (67 h), and then irradiated with 2 Gy gamma-radiation ((60)Co) in different groups. After treatment, viability of the cells, colony forming ability and DNA damages were obtained by blue dye exclusion, colony formation and alkaline comet assay, respectively. Our results showed that methoxyamine and resveratrol could significantly reduce colony number and induce the DNA damages of glioblastoma spheroid cells treated with iododeoxyuridine in combination with gamma-rays. Therefore, methoxyamine as base excision repair inhibitor and resveratrol as hypoxia inducible factor 1-alpha inhibitor in combination with iododeoxyuridine as radiosensitizer enhanced the radiosensitization of glioblastoma spheroid cells.

Silibinin Preferentially Radiosensitizes Prostate Cancer by Inhibiting DNA Repair Signaling

Radiotherapy, a frequent mode of cancer treatment, is often restricted by dose-related toxicity and development of therapeutic resistance. To develop a novel and selective radiosensitizer, we studied the radiosensitizing effects and associated mechanisms of silibinin in prostate cancer. The radiosensitizing effect of silibinin with ionizing radiation (IR) was assessed on radioresistant prostate cancer cell lines by clonogenic, cell cycle, cell death, and DNA repair assays. Tumor xenograft growth, immunohistochemical (IHC) analysis of tumor tissues, and toxicity-related parameters were measured in vivo. Silibinin (25 μmol/L) enhanced IR (2.5-10 Gy)-caused inhibition (up to 96%, P < 0.001) of colony formation selectively in prostate cancer cells, and prolonged and enhanced IR-caused G2-M arrest, apoptosis, and ROS production. Mechanistically, silibinin inhibited IR-induced DNA repair (ATM and Chk1/2) and EGFR signaling and attenuated the levels of antiapoptotic proteins. Specifically, silibinin suppressed IR-induced nuclear translocation of EGFR and DNA-PK, an important mediator of DSB repair, leading to an increased number of γ-H2AX (ser139) foci suggesting lesser DNA repair. In vivo, silibinin strongly radiosensitized DU145 tumor xenograft inhibition (84%, P < 0.01) with higher apoptotic response (10-fold, P < 0.01) and reduced repair of DNA damage, and rescued the mice from IR-induced toxicity and hematopoietic injury. Overall, silibinin enhanced the radiotherapeutic response via suppressing IR-induced prosurvival signaling and DSB repair by inhibiting nuclear translocation of EGFR and DNA-PK. Because silibinin is already in phase II clinical trial for prostate cancer patients, the present finding has translational relevance for radioresistant prostate cancer.

Resveratrol in the treatment of pancreatic cancer

Pancreatic cancer (PCa), which is now the fourth most frequent cause of cancer-related death, has a median survival of less than 6 months and a 5-year survival rate of <6%. The hallmarks of this cancer include poor outcome, short survival duration, and resistance to therapy. The poor prognosis of PCa is related to its local recurrence, lymph node and liver metastases, and peritoneal dissemination. Recent studies have indicated that resveratrol has cancer-chemopreventive and anticancer activities. In this short review we summarize the chemopreventive and treatment effects of resveratrol in PCa, as follows: resveratrol inhibits the proliferation of pancreatic cancer cells; induces apoptosis and cell cycle arrest; inhibits metastasis and invasion of PCa cells; inhibits the proliferation and viability of PCa stem cells; enhances the chemoradiosensitization of PCa cells; and can affect diabetes mellitus in addition to PCa. On the basis of these data, resveratrol may be considered a potential anticancer agent for the treatment of PCa.

A 3D-microtissue-based phenotypic screening of radiation resistant tumor cells with synchronized chemotherapeutic treatment

Background

Radiation resistance presents a challenge to the effective treatment of cancer. If therapeutic compounds were capable of resensitizing resistant tumours then a concurrent chemo-radiation treatment could be used to overcome radiation resistance.

Methods

We have developed a phenotypic assay to investigate the response of radiation resistant breast cancer cells grown in 3D-microtissue spheroids to combinations of radiation and established chemotherapeutic drugs. The effects were quantified by real time high content imaging of GFP detection area over 14 days. Ten established chemotherapeutic drugs were tested for their ability to enhance the effects of radiation.

Results

Of ten analysed chemotherapeutics, vinblastine was the most effective compound, with docetaxel and doxorubicine being less effective in combination with radiation. To investigate the response in a model closer to the in vivo situation we investigated the response of heterotypic 3D microtissues containing both fibroblasts and breast cancer cells. Drug treatment of these heterotypic 3D cultures confirmed treatment with radiation plus vinblastine to be additive in causing breast cancer growth inhibition. We have validated the screen by comparing radiation sensitizing effects of known chemotherapeutic agents. In both monotypic and heterotypic models the concurrent treatment of vinblastine and radiation proved more effective inhibitors of mammary cancer cell growth. The effective concentration range of both vinblastine and radiation are within the range used in treatment, suggesting the 3D model will offer a highly relevant screen for novel compounds.

Conclusions

For the first time comfortable 3D cell-based phenotypic assay is available, that allows high throughput screening of compounds with radiation therapy modulating capacity, opening the field to drug discovery.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1481-9) contains supplementary material, which is available to authorized users.

Effect of the coffee ingredient cafestol on head and neck squamous cell carcinoma cell lines

BACKGROUND AND PURPOSE

Cafestol is a diterpene molecule found in coffee beans and has anticarcinogenic properties. The aim of the study was to examine the effects of cafestol in head and neck squamous cell carcinoma (HNSCC) cells.

MATERIALS AND METHODS

Three HNSCC cell lines (SCC25, CAL27 and FaDu) were treated with increasing doses of cafestol. Then combination experiments with cisplatin and irradiation were carried out. Drug interactions and possible synergy were calculated using the combination index analysis. Clonogenic assays were performed after irradiation with 2, 4, 6 and 8 Gy, respectively, and the rate of apoptosis was measured with flow cytometry.

RESULTS

Treatment of HNSCC cells with cafestol leads to a dose-dependent reduction of cell viability and to induction of apoptosis. Combination with irradiation shows a reduction of clonogenic survival compared to each treatment method alone. In two of the cell lines a significant additive effect was observed.

CONCLUSION

Cafestol is a naturally occurring effective compound with growth-inhibiting properties in head and neck cancer cells. Moreover, it leads to a significant inhibition of colony formation.

Plumbagin reduces human colon cancer cell survival by inducing cell cycle arrest and mitochondria-mediated apoptosis

Despite increased use of early detection methods and more aggressive treatment strategies, the worldwide incidence of colorectal cancer is still on the rise. Consequently, it remains urgent to identify novel agents with enhanced efficacy in prevention and/or therapeutic protocols. Our studies focused on the use of Plumbagin, a natural phytochemical that showed promising results against other tumor types, to determine its effectiveness in blocking the proliferation and survival of colon cancer cells in experimental protocols mimicking the environment in primary tumors (attached culture conditions) and in circulating tumor cells (unattached conditions). Under both experimental settings, exposure of HCT116 cells to Plumbagin concentrations in the low micromolar range resulted in cell cycle arrest at the G1 phase, apoptosis via the mitochondrial cell death pathway, and increased production of reactive oxygen species. The cell cycle effects were more noticeable in attached cells, whereas the induction of cell death was more evident in unattached cells. These effects were consistent with the nature and the magnitude of the alterations induced by Plumbagin on the expression levels of a set of proteins known to play key roles in the regulation of cell cycle dynamics, apoptosis mechanisms and cell proliferation. In light of its previously reported lack of toxicity on normal colon cells and the striking anti-survival effect on colon cancer cells observed in our study, Plumbagin should be considered a promising drug for the treatment of colon cancer.

Research progress on the anticarcinogenic actions and mechanisms of ellagic acid

Cancer is a leading cause of death worldwide. Cancer treatments by chemotherapeutic agents, surgery, and radiation have not been highly effective in reducing the incidence of cancers and increasing the survival rate of cancer patients. In recent years, plant-derived compounds have attracted considerable attention as alternative cancer remedies for enhancing cancer prevention and treatment because of their low toxicities, low costs, and low side effects. Ellagic acid (EA) is a natural phenolic constituent. Recent in vitro and in vivo experiments have revealed that EA elicits anticarcinogenic effects by inhibiting tumor cell proliferation, inducing apoptosis, breaking DNA binding to carcinogens, blocking virus infection, and disturbing inflammation, angiogenesis, and drug-resistance processes required for tumor growth and metastasis. This review enumerates the anticarcinogenic actions and mechanisms of EA. It also discusses future directions on the applications of EA.

Radioprotectors - the evergreen topic

To protect organisms from ionizing radiation (IR), and to reduce morbidity or mortality, various agents, called radioprotectors, have been utilized. Because radiation-induced cellular damage is attributed primarily to the harmful effects of free radicals, molecules with radical-scavenging properties are particularly promising as radioprotectors. Early development of such agents focused on thiol synthetic compounds, known as WR protectors, but only amifostine (WR-2721) has been used in clinical trials as an officially approved radioprotector. Besides thiol compounds, various compounds with different chemical structure were investigated, but an ideal radioprotector has not been found yet. Plants and natural products have been evaluated as promising sources of radioprotectors because of their low toxicity, although they exhibit an inferior protection level compared to synthetic thiol compounds. Active plant constituents seem to exert the radioprotection through antioxidant and free radical-scavenging activities. Our research established that plants containing polyphenolic compounds (raspberry, blueberry, strawberry, grape, etc.) exhibit antioxidative activities and protect genetic material from IR.

Sesquiterpene lactones: adverse health effects and toxicity mechanisms

Sesquiterpene lactones (STLs) present a wide range of biological activities, mostly based on their alkylating capabilities, which underlie their therapeutic potential. These compounds are the active constituents of a variety of plants, frequently used as herbal remedies. STLs such as artemisinin and its derivatives are in use as first-line antimalarials while others, such as parthenolide, have recently reached cancer clinical trials. However, the toxicological profile of these compounds must be thoroughly characterized, since the same properties that make STL useful medicines can also cause severe toxicity. STL-containing plants have long been known to induce a contact dermatitis in exposed farm workers, and also to cause several toxic syndromes in farm animals. More recently, concerns are been raised regarding the genotoxic potential of these compounds and the embryotoxicity of artemisinins. A growing number of STLs are being reported to be mutagenic in different in vitro and in vivo assays. As yet no systematic studies have been published, but the genotoxicity of STLs seems to depend not so much on direct DNA alkylation as on oxidative DNA damage and other partially elucidated mechanisms. As the medicinal use of these compounds increases, further studies of their toxic potential are needed, especially those focusing on the structural determinants of genotoxicity and embryotoxicity.

Resveratrol potentiates effects of simvastatin on inhibition of rat ovarian theca-interstitial cells steroidogenesis

BACKGROUND

Polycystic ovary syndrome (PCOS) is characterized by ovarian enlargement, hyperplastic theca compartment and increased androgen production due to, at least in part, excessive expression of several key genes involved in steroidogenesis. Previously, our group has demonstrated that simvastatin, competitive inhibitor of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), a rate-limiting step of the mevalonate pathway, reduces rat-theca interstitial cell steroidogenesis by inhibiting Cyp17a1 gene expression, the key enzyme of the androgen biosynthesis pathway. Recently, we demonstrated that resveratrol, a bioflavonoid abundant in red grapes, decreases rat theca-interstitial cell steroidogenesis and this suppressive effect is mediated through mechanisms independent of the mevalonate pathway. The present study evaluated the effect of combining simvastatin and resveratrol treatments on rat theca-interstitial cell steroidogenesis.

METHODS

Rat theca-interstitial cells isolated from 30 day-old female rats were cultured for up to 48 h with or without simvastatin (1 μM) and/or resveratrol (3-10 μM). Steroidogenic enzymes gene expression was evaluated by quantitative real time PCR and steroid levels were measured by liquid chromatography-mass spectrometry. Comparisons between groups were performed using ANOVA and Tukey test.

RESULTS

Resveratrol potentiated inhibitory effects of simvastatin on androstenedione and androsterone production in theca-interstitial cells. This suppressive effect correlated with profound inhibition in Cyp17a1 mRNA expression in the presence of a combination of resveratrol and simvastatin.

CONCLUSIONS

The present findings indicate that resveratrol potentiates the simvastatin-induced inhibitory effect on theca-interstitial cell androgen production, raising the possibility of development of novel treatments of PCOS.

Curcumin protection activities against γ-rays-induced molecular and biochemical lesions

Background

Curcumin is a yellow-pigment phenolic compound used as a food spice and has a broad spectrum of antioxidant, anti-carcinogenic, anti-mutagenic and anti-inflammatory properties.

Methods

Radio-protective efficacy of curcumin; diferuloylmethane (C₂₁H₂₀O₆) was evaluated using molecular and biochemical assays in male mice after exposure to 3 Gy γ-rays. Curcumin was given at a dose of 400 μmol/ kg body weight via gastric tubes for 5 following days either pre-, post- or both pre- and post-exposure.

Results

The incidence of aberrant cells and aberration types (mostly chromatids, breaks and fragments) was reduced with curcumin dosage as compared to irradiated group. Thiobarbituric acid reactive substances (TBARS), hydroperoxide (HP), xanthine oxidase (XO) and apoptotic markers (DNA- fragmentation and caspase-3 activation) were increased significantly, whereas levels of glutathione (GSH) and the enzymatic antioxidants [Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] were significantly depleted in γ-irradiated mice. Curcumin treatments of mice groups including the 5 days pre-irradiation treated group (protected), the 5 days post-irradiation treated group (treated), and the curcumin treated group 5 days pre- and post-irradiation (protracted), have attenuated the liver toxic effects of γ-rays as manifested by reducing the levels of TBARS, HP, XO and DNA fragmentation. Curcumin has also rescued the depletion of GSH and the enzymatic-antioxidant status.

Conclusions

Curcumin has significant radio-protective and radio-recovery activities in γ-irradiated mice. It has antioxidant potential against γ-rays-induced cytogenetic, molecular and biochemical lesions in mice.