Apoptosis-inducing effects of Melissa officinalis L. essential oil in glioblastoma multiforme cells

Melissa officinalisessential oil loaded polycaprolactone membranes: evaluation of antimicrobial activities and cytocompatibility for tissue engineering applications

Antimicrobial biomaterials play important role in tissue engineering applications to protect damaged tissue from infections. The aim of this study is producing antimicrobial polycaprolactone (PCL) membranes by using a plant based antimicrobial agent. Therefore,Melissa officinalisessential oil (MEO) was investigated against ten types of microorganisms and remarkable antimicrobial activity was demonstrated. PCL:MEO membranes were prepared by solvent casting method by mixing MEO into PCL in various ratios (PCL:0M, PCL:0.25M, PCL:0.5M, and PCL:1M w/w). Water contact angle measurements showed that hydrophilicity of the membranes increased with increasing concentrations of MEO from 103.44° to 83.36° for PCL:0M and PCL:1M, respectively. It was determined that there was an inverse relationship between the MEO concentration and the mechanical properties. Notable antioxidant activity of PCL/MEO membranes was exhibited by the inhibition percent of 2,2-diphenyl-1-picrylhydrazyl (DPPH) which was increased from 24.74% to 44.79% for PCL:0M and PCL:1M, respectively. The antimicrobial activity of MEO was also highly maintained in PCL membranes. For PCL/MEO membranes, at least 99.9% of microorganisms were inhibited. Cytocompatibility of the membranes were investigated by resazurin assay, scanning electron microscopy analysis and 4',6-diamidino-2-phenylindole (DAPI) staining. PCL:0.25M and PCL:0.5M membranes supported the viability of L929 cells more than 87% when compared to PCL:0M membranes on day 6. However, the viability of L929 cells on PCL:1M membranes was about 43% indicating significant decrease on cellular activity. In conclusion, PCL:0.25M and PCL:0.5M membranes with their high antimicrobial activity, acceptable mechanical properties and cytocompatible properties, they can be considered as an alternative biomaterial for tissue engineering applications.

Exploring the Potent Anticancer Activity of Essential Oils and Their Bioactive Compounds: Mechanisms and Prospects for Future Cancer Therapy

Cancer is one of the leading causes of death worldwide, affecting millions of people each year. Fortunately, the last decades have been marked by considerable advances in the field of cancer therapy. Researchers have discovered many natural substances, some of which are isolated from plants that have promising anti-tumor activity. Among these, essential oils (EOs) and their constituents have been widely studied and shown potent anticancer activities, both in vitro and in vivo. However, despite the promising results, the precise mechanisms of action of EOs and their bioactive compounds are still poorly understood. Further research is needed to better understand these mechanisms, as well as their effectiveness and safety in use. Furthermore, the use of EOs as anticancer drugs is complex, as it requires absolute pharmacodynamic specificity and selectivity, as well as an appropriate formulation for effective administration. In this study, we present a synthesis of recent work on the mechanisms of anticancer action of EOs and their bioactive compounds, examining the results of various in vitro and in vivo studies. We also review future research prospects in this exciting field, as well as potential implications for the development of new cancer drugs.

Elucidating the Anti-Tumorigenic Efficacy of Oltipraz, a Dithiolethione, in Glioblastoma

Glioblastoma multiforme (GBM), the most aggressive primary brain tumor, displays a highly infiltrative growth pattern and remains refractory to chemotherapy. Phytochemicals carrying specificity and low cytotoxicity may serve as potent and safer alternatives to conventional chemotherapy for treating GBM. We have evaluated the anticancer effects of Oltipraz (Olt), a synthetic dithiolethione found in many vegetables, including crucifers. While Olt exposure was non-toxic to the HEK-293 cell line, it impaired the cell growth in three GBM cell lines (LN18, LN229, and U-87 MG), arresting those at the G2/M phase. Olt-exposed GBM cells induced the generation of reactive oxygen species (ROS), mitochondrial depolarization, caspase 3/7-mediated apoptosis, nuclear condensation, and DNA fragmentation, and decreased glutathione, a natural ROS scavenger, as well as vimentin and β-catenin, the EMT-associated markers. Its effect on a subpopulation of GBM cells exhibiting glioblastoma stem cell (GSCs)-like characteristics revealed a reduced expression of Oct4, Sox2, CD133, CD44, and a decrease in ALDH⁺, Nestin⁺ and CD44⁺ cells. In contrast, there was an increase in the expression of GFAP and GFAP⁺ cells. The Olt also significantly suppressed the oncosphere-forming ability of cells. Its efficacy was further validated in vivo, wherein oral administration of Olt could suppress the ectopically established GBM tumor growth in SCID mice. However, there was no alteration in body weight, organ ratio, and biochemical parameters, reflecting the absence of any toxicity otherwise. Together, our findings could demonstrate the promising chemotherapeutic efficacy of Olt with potential implications in treating GBM.

Essential oils as anticancer agents: Potential role in malignancies, drug delivery mechanisms, and immune system enhancement

Cancer retains a central place in fatality rates among the wide variety of diseases known world over, and the conventional synthetic medicaments, albeit used until now, produce numerous side effects. As a result, newer, better, and safer alternatives such as natural plant products, are gravely required. Essential oils (EOs) offer a plethora of bioactivities including antibacterial, antiviral, antioxidant, and anticancer properties, therefore, the use of EOs in combination with synthetic drugs or aromatherapy continues to be popular in many settings. In view of the paramount importance of EOs and their potential bioactivities, this review summarizes the current knowledge on the interconnection between EOs and cancer treatment. In particular, the current review presents an updated summary of the chemical composition of EOs, their current applications in cancer treatments based on clinical studies, and the mechanism of action against the cancer cell lines. Similarly, an overview of using EOs in aromatherapy and enhancing immunity during cancer treatment is provided. Further, this review focuses on the recent technological advancements such as the loading of EOs using protein microspheres, ligands, or nanoemulsions/nanoencapsulation, which offer multiple benefits in cancer treatment via site-specific and target-oriented delivery of drugs. The continuing clinical studies of EOs implicate that their pharmacological applications are a rewarding research area.

Chemoprevention and therapeutic role of essential oils and phenolic compounds: Modeling tumor microenvironment in glioblastoma

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. Current treatments available for GBM entails surgical resection followed by temozolomide chemotherapy and/or radiotherapy, which are associated with multidrug resistance and severe side effects. While this treatment could yield good results, in almost all cases, patients suffer from relapse, which leads to reduced survival rates. Thus, therapeutic approaches with improved efficiency and reduced off-target risks are needed to overcome these problems. Regarding this, natural products appear as a safe and attractive strategy as chemotherapeutic agents or adjuvants in the treatment of GBM. Besides the increasing role of natural compounds for chemoprevention of GBM, it has been proposed to prevent carcinogenesis and metastasis of GBM. Numerous investigations showed that natural products are able to inhibit proliferation and angiogenesis, to induce apoptosis, and to target GBM stem cells, which are associated with tumor development and recurrence. This review gives a timely and comprehensive overview of the current literature regarding chemoprevention and therapy of GBM by natural products with a focus on essential oils and phenolic compounds and their molecular mechanisms.

Melissa officinalis Extract Induces Apoptosis and Inhibits Migration in Human Colorectal Cancer Cells

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Lifestyle-related factors, such as diet, are associated with the development of CRC. Cumulating evidence indicates noticeable chemopreventive effects of phytochemicals on CRC, suggesting that drinking herbal tea potentially reduces the risk of distal colon cancer via its antiproliferative and anti-angiogenic activities. We examine the antitumor effects of nine components frequently found in herbal tea and uncover the underlying molecular mechanism. Among them, the hot water extract of Melissa officinalis (MO) exhibited the highest anticancer activity on CRC cells. We revealed that MO reduced cell proliferation, induced cell cycle arrest at the G₂/M phase, triggered caspase-dependent apoptotic cell death, and inhibited cell migration ability by modulating the epithelial-mesenchymal transition in HCT116 CRC cells. To examine the metabolite composition in the MO hot water extract, we applied mass spectrometry-based analysis and identified 67 compounds. Among them, the phenolic compounds, including lignans, phenylpropanoids, and polyketides, are widely found in natural products and possess various bioactivities such as anti-inflammatory, antioxidation, and anticancer effects. The results indicate that herbal tea consumption benefits CRC prevention and management.

Traditional, phytochemical, and biological aspects of Rosa alba L.: a systematic review

Background

Rosa alba L. belongs to the family Rosaceae. This species is widely cultivated in Europe, Asia, North America, and Northwest Africa due to its fragrance, ornamental, and medicinal values. It is commonly known as white oil-bearing rose, white rose, white rose of York, backyard rose, and sufaid gulab.

Main text

Rosa alba L. has many biological properties like antioxidant, antimicrobial, antifungal, antifertility, teratogenic, memory enhancing, cytotoxic, and genotoxic activities. The essential oil of Rosa alba L. possesses good antimicrobial activity and consists of many chemical constituents like- citronellol, geraniol, nerol, linalool, citral, carvacrol, eugenol, etc.

Conclusion

This article briefly reviews the cultivation, traditional uses, phytochemistry, and biological activities of Rosa alba L. Many research papers have been published on the proposed plant and still, there is a very vast scope of research on it. Therefore, this review will be very fruitful for those scientists who are doing or plan to do research work on this plant. All the scientific findings written in this review are explored from Google web, Google Scholar, PubMed, ScienceDirect, Medicinal and Aromatic Plants Abstracts (MAPA), and SciFinder. To date, it is the first systematic review article of such kind, on this plant.

Chemical Investigation and Screening of Anti-Proliferative Activity on Human Cell Lines of Pure and Nano-Formulated Lavandin Essential Oil

Lavandin essential oil (LEO), a natural sterile hybrid obtained by crossbreeding L. angustifolia × L. latifolia, is mainly composed by active components belonging to the family of terpenes endowed with relevant anti-proliferative activity, which can be enhanced by proper application of nanotechnology. In particular, this study reports the chemical characterization and the screening of the anti-proliferative activity on different human cell lines of pure and nano-formulated lavandin essential oil (EO). LEO and its formulation (NanoLEO) were analyzed by HS/GC-MS (Headspace/Gas Chromatography-Mass Spectrometry) to describe and compare their chemical volatile composition. The most abundant compounds were linalool and 1,8-cineole (LEO: 28.6%; 27.4%) (NanoLEO: 60.4%; 12.6%) followed by α-pinene (LEO: 9.6%; NanoLEO: 4.5%), camphor (LEO: 6.5%; NanoLEO: 7.0%) and linalyl acetate (LEO: 6.5%; NanoLEO: 3.6%). The cytotoxic effects of LEO and NanoLEO were investigated on human neuroblastoma cells (SHSY5Y), human breast adenocarcinoma cells (MCF-7), human lymphoblastic leukemia cells (CCRF CEM), human colorectal adenocarcinoma cells (Caco-2) and one normal breast epithelial cell (MCF10A) by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide)-assay. Caco-2, MCF7 and MCF10A normal cells resulted more resistant to the treatment with LEO, while CCRF-CEM and SHSY5Y cells were more sensitive. The antiproliferative effect of LEO resulted amplified when the essential oil was supplied as nanoformulation, mainly in Caco-2 cells. Scanning and transmission electron microscopy investigations were carried out on Caco-2 cells to outline at ultrastructural level possible affections induced by LEO and NanoLEO treatments.

Lemon Grass Essential Oil Does not Modulate Cancer Cells Multidrug Resistance by Citral-Its Dominant and Strongly Antimicrobial Compound

With strong antimicrobial properties, citral has been repeatedly reported to be the dominant component of lemongrass essential oil. Here, we report on a comparison of the antimicrobial and anticancer activity of citral and lemongrass essential oil. The lemongrass essential oil was prepared by the vacuum distillation of fresh Cymbopogon leaves, with a yield of 0.5% (w/w). Citral content was measured by gas chromatography/high-resolution mass spectrometry (GC-HRMS) and determined to be 63%. Antimicrobial activity was tested by the broth dilution method, showing strong activity against all tested bacteria and fungi. Citral was up to 100 times more active than the lemongrass essential oil. Similarly, both citral and essential oils inhibited bacterial communication and adhesion during P. aeruginosa and S. aureus biofilm formation; however, the biofilm prevention activity of citral was significantly higher. Both the essential oil and citral disrupted the maturated P. aeruginosa biofilm with the IC₅₀ 7.3 ± 0.4 and 0.1 ± 0.01 mL/L, respectively. Although it may seem that the citral is the main biologically active compound of lemongrass essential oil and the accompanying components have instead antagonistic effects, we determined that the lemongrass essential oil-sensitized methicillin-resistant S. aureus (MRSA) and doxorubicin-resistant ovarian carcinoma cells and that this activity was not caused by citral. A 1 mL/L dose of oil-sensitized MRSA to methicillin up to 9.6 times and a dose of 10 µL/L-sensitized ovarian carcinoma to doxorubicin up to 1.8 times. The mode of multidrug resistance modulation could be due to P-glycoprotein efflux pump inhibition. Therefore, the natural mixture of compounds present in the lemongrass essential oil provides beneficial effects and its direct use may be preferred to its use as a template for citral isolation.

Lemon Balm Extracts Prevent Breast Cancer Progression In Vitro and In Ovo on Chorioallantoic Membrane Assay

Breast cancer is the most frequently diagnosed malignant pathology, representing the primary cause of cancer death in women. Natural products are an appealing strategy to limit the progression of the disease. Targeting angiogenesis in breast cancer may positively impact on poor prognosis of breast cancer. As source of natural compounds, we investigated the leaves of Melissa officinalis L. (MO), known as lemon balm, an aromatic plant that spontaneously grows in the South and Western areas of Romania, being traditionally recommended as anxiolytic, antispasmodic, or as digestive remedy. Our aim was to investigate the phytochemical profiling and the antiangiogenic and chemopreventive bioactivity of MO from Banat region, on breast cancer. Two ethanolic extracts of MO (MOE96 and MOE70) and one methanolic extract (MOM80) were subjected to polyphenol and triterpene profiling by HPLC-MS, and the antioxidant capacity was evaluated. The antiangiogenic potential was investigated using the chorioallantoic membrane assay (CAM). The MTT(3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide) assay was used to investigate the cytotoxic effects on MCF-7 and MDA-MB-231breast cancer cells, as well as on MCF-10A normal breast epithelial cells, while apoptosis was performed by DAPI staining. Rosmarinic acid (RA) and ursolic acid (UA) were revealed as dominant phytocompounds. The highest concentration in phytochemicals were found in MOM80; MOE96 was more concentrated in UA, while MOE70 extracted more RA. MOE96 inhibited cancer progression and angiogenesis in the in ovo CAM model using MDA-MB-231 cells, inhibiting breast cancer progression and angiogenesis for the MDA-MB-231 breast cancer cell line; no secondary tumoral areas were registered, indicative for a preventive effect against breast tumor cell invasiveness. The highest cell inhibitory activity was also exhibited by MOE96, in particular against the estrogen receptor positive MCF7 breast cancer cell line, with no cytotoxic effect on healthy cells. The estrogen receptor positive MCF7 cell line proved to be more sensitive to the extract antiproliferative activity than the triple negative MDA-MB-231 breast cancer cell line. Nevertheless, the chemopreventive potential of MOE96 extract is phenotype-dependent and is rather related to the apoptosis and antiangiogenic effects suggesting a multitargeted mechanism of action due to its multiple compound composition next to a concentration ratio of RA : UA in favor of UA.

Targets and pathways involved in the antitumor activity of citral and its stereo-isomers

This review provides a comprehensive analysis of the anticancer potential of the natural product citral (CIT) found in many plants and essential oils, and extensively used in the food and cosmetic industry. CIT is composed of two stereoisomers, the trans-isomer geranial being a more potent anticancer compound than the cis-isomer neral. CIT inhibits cancer cell proliferation and induces cancer cell apoptosis. Its pluri-factorial mechanism of anticancer activity is essentially based on three pillars: (i) a drug-induced accumulation of reactive oxygen species in cancer cells leading to an oxidative burst and DNA damages, (ii) a colchicine-like inhibition of tubulin polymerization and promotion of microtubule depolymerization, associated with an inhibition of the microtubule affinity-regulating kinase MARK4, and (iii) a potent inhibition of the aldehyde dehydrogenase isoform ALDH1A3 which is associated with cancer stem cell proliferation and chemoresistance. This unique combination of targets and pathways confers a significant anticancer potential. However, the intrinsic potency of CIT is limited, mainly because the drug is not very stable and has a low bioavailability and it does not present a high selectivity for cancer cells versus non-tumor cells. Stable formulations of CIT, using cyclodextrins, biodegradable polymers, or various nano-structured particles have been designed to enhance the bioavailability, to increase the effective doses window and to promote the anticancer activity. The lack of tumor cell selectivity is more problematic and limits the use of the drug in cancer therapy. Nevertheless, CIT offers interesting perspectives to design more potent analogues and drug combinations with a reinforced antitumor potential.

Agro-ecological cultivation, secondary metabolite characteristics and microbiological tests of lemon balm (Melissa officinalis) – the variety Citronella

Lemon balm (Melissa officinalis L.) is a native of the eastern Mediterranean region southward to Israel and Syria and eastward through the Crimea, the Caucasus, and Northern Iran to the Tien Shan and the Pamirs. It appears to have been naturalized in the Central Europe including the Carpathian Ukraine and Eastern Slovakia. The objective of this study was characterization of the chemical composition and antimicrobial activity of essential oils from Melissa officinalis L. variety Citronella in the conditions of cultivation in a lowland region of the Ukrainian Carpathians. Plant material, balm dry leaves and leafy tops of the shoots, were grown in a small-scale cultivation ground at the Zakarpatian Institute of Agroindustrial Production in Velikaja Bakta, Carpathian-Ukraine. The Citronella variety is used for herb production. Essential oil from balm parts (herb and leaves) was isolated by distillation with boiled water. Hydro-distillation lasted for 4 hours, sample weights were 10 g of dry drug matter. A modified Coocking & Middleton distillation apparatus was used. Identification and evaluation of balm essential oil were carried out using the selected analytical method of HPLC-DAD analysis. The final balm extract was analyzed directly on a Dionex UltiMate 3000 system. The analysis of balm essential oil was carried out using a gas chromatograph Varian 3090, connected to a MS Saturn 2100T integrator. The sensitivity of microorganisms to plant extracts was determined by the disk diffusion test (with disk diameter of 6 mm). The quantitative and qualitative characteristics of balm essential oil (0.05–0.12% v/w) and its composition show very high content of α-citrale (geranial) (44%), β-citrale (neral) (29%) and citronellal (9%). Rosmarinic acid can be extracted from leaves and its content equals up to 1.7 ± 0.1%. Composition of the natural substances depends on the balm taxon, origin, soil and climatic growing conditions, and methods of harvest and isolation and effective weed control which are used. Antibacterial effect of the oil showed low activity against all bacterial strains. Our results confirmed higher activity of EOs against Gram-positive bacteria than Gram-negative. The balm essential oil displayed antimitotic effect especially towards Candida glabrata clinical strain. Thus, studies have shown that Melissa officinalis variety of Citronella in the conditions of cultivation in the lowland region of Carpathian-Ukraine according to biochemical characteristics and microbiological properties corresponds to world analogues.

Anticancer Properties of Essential Oils and Other Natural Products

Essential oils are secondary metabolites with a key-role in plants protection, consisting primarily of terpenes with a volatile nature and a diverse array of chemical structures. Essential oils exhibit a wide range of bioactivities, especially antimicrobial activity, and have long been utilized for treating various human ailments and diseases. Cancer cell prevention and cytotoxicity are exhibited through a wide range of mechanisms of action, with more recent research focusing on synergistic and antagonistic activity between specific essential oils major and minor components. Essential oils have been shown to possess cancer cell targeting activity and are able to increase the efficacy of commonly used chemotherapy drugs including paclitaxel and docetaxel, having also shown proimmune functions when administered to the cancer patient. The present review represents a state-of-the-art review of the research behind the application of EOs as anticancer agents both in vitro and in vivo. Cancer cell target specificity and the use of EOs in combination with conventional chemotherapeutic strategies are also explored.

Pomolic acid induces apoptosis and inhibits multidrug resistance protein MRP1 and migration in glioblastoma cells

Glioblastoma (GBM), the most aggressive of primary brain tumors, determine short survival and poor quality of life. Therapies used for its treatment are not effective and chemotherapy failure is partially due to multidrug resistance (MDR) mechanisms present in the tumor cells. New therapeutic strategies are needed in order to improve survival in GBM. The present study investigated the activity of the pentacyclic triterpene pomolic acid (PA) in GBM. Pomolic acid decreased the viability and induced apoptosis of GBM cells as demonstrated by DNA fragmentation. It also induced uncoupling of mitochondria membrane potential and activation of caspase-3 and -9. Pomolic acid-induced apoptosis is dependent on reactive oxygen species (ROS) production as it is inhibited by anti-oxidant treatment. Pomolic acid also down-modulated the activity of the multidrug resistance associated protein 1 (MRP1) and inhibited migration of GBM cells. These results show that PA acts on several pathways of GBM drug resistance and therefore may be of potential interest for the treatment of this tumor.

Biological Activities of Essential Oils: From Plant Chemoecology to Traditional Healing Systems

Essential oils are complex mixtures of hydrocarbons and their oxygenated derivatives arising from two different isoprenoid pathways. Essential oils are produced by glandular trichomes and other secretory structures, specialized secretory tissues mainly diffused onto the surface of plant organs, particularly flowers and leaves, thus exerting a pivotal ecological role in plant. In addition, essential oils have been used, since ancient times, in many different traditional healing systems all over the world, because of their biological activities. Many preclinical studies have documented antimicrobial, antioxidant, anti-inflammatory and anticancer activities of essential oils in a number of cell and animal models, also elucidating their mechanism of action and pharmacological targets, though the paucity of in human studies limits the potential of essential oils as effective and safe phytotherapeutic agents. More well-designed clinical trials are needed in order to ascertain the real efficacy and safety of these plant products.

Melissa officinalis L. - A review of its traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Melissa officinalis L. is a medicinal plant that has long been used in different ethno-medical systems especially in the European Traditional Medicine and the Iranian Traditional Medicine for the treatment of several diseases. It is also widely used as a vegetable and to add flavor to dishes

AIM OF THE REVIEW

This review aimed to provide a summary on the botanical characterization, traditional uses, phytochemistry, pharmacological activities, pharmacokinetics and toxicity of M. officinalis, and discusses research gaps and future opportunities for investigations on this plant.

MATERIALS AND METHODS

We extensively reviewed major unpublished old texts, and published and electronic literature on traditional medicines of different regions of the world to find traditional uses of M. officinalis. Electronic databases including Web of Science, PubMed, ScienceDirect, Google Scholar and Scopus were searched to find articles (published between 1956 and 2015) on pharmacology and phytochemistry of M. officinalis.

RESULTS

Traditional uses of M. officinalis have been recorded mostly in European countries, Mediterranean region and Middle East countries. Phytochemical investigations revealed that this plant contains volatile compounds, triterpenoids, phenolic acids and flavonoids. Crude extracts and pure compounds isolated from M. officinalis exhibited numerous pharmacological effects, from which only anxiolytic, antiviral and antispasmodic activities of this plant as well as its effects on mood, cognition and memory have been shown in clinical trials. AChE inhibitory activity, stimulation of the acetylcholine and GABAA receptors, as well as inhibition of matrix metallo proteinase-2 are the main mechanisms proposed for the widely discussed neurological effects of this plant.

CONCLUSIONS

Modern pharmacological studies have now validated many traditional uses of M. officinalis. The data reviewed here revealed that M. officinalis is a potential source for the treatment of a wide range of diseases especially anxiety and some other CNS disorders, though confirmatory trials are warranted to substantiate these effects in the clinical setting. Data regarding many aspects of this plant such as mechanisms of actions, pharmacokinetics, adverse effects of the extracts, potential interactions with standard-of-care medications and active compounds is still limited which call for additional studies particularly in humans.

Changes in O-Linked N-Acetylglucosamine (O-GlcNAc) Homeostasis Activate the p53 Pathway in Ovarian Cancer Cells

O-GlcNAcylation is a dynamic post-translational modification consisting of the addition of a single N-acetylglucosamine sugar to serine and threonine residues in proteins by the enzyme O-linked β-N-acetylglucosamine transferase (OGT), whereas the enzyme O-GlcNAcase (OGA) removes the modification. In cancer, tumor samples present with altered O-GlcNAcylation; however, changes in O-GlcNAcylation are not consistent between tumor types. Interestingly, the tumor suppressor p53 is modified by O-GlcNAc, and most solid tumors contain mutations in p53 leading to the loss of p53 function. Because ovarian cancer has a high frequency of p53 mutation rates, we decided to investigate the relationship between O-GlcNAcylation and p53 function in ovarian cancer. We measured a significant decrease in O-GlcNAcylation of tumor tissue in an ovarian tumor microarray. Furthermore, O-GlcNAcylation was increased, and OGA protein and mRNA levels were decreased in ovarian tumor cell lines not expressing the protein p53. Treatment with the OGA inhibitor Thiamet-G (TMG), silencing of OGA, or overexpression of OGA and OGT led to p53 stabilization, increased nuclear localization, and increased protein and mRNA levels of p53 target genes. These data suggest that changes in O-GlcNAc homeostasis activate the p53 pathway. Combination treatment of the chemotherapeutic cisplatin with TMG decreased tumor cell growth and enhanced cell cycle arrest without impairing cytotoxicity. The effects of TMG on tumor cell growth were partially dependent on wild type p53 activation. In conclusion, changes in O-GlcNAc homeostasis activate the wild type p53 pathway in ovarian cancer cells, and OGA inhibition has the potential as an adjuvant treatment for ovarian carcinoma.

Cytokine-induced killer cells induce apoptosis and inhibit the Akt/nuclear factor-κB signaling pathway in cisplatin-resistant human glioma U87MG cells

Despite advances in the development of treatment methods, glioma remains among the cancer types with a high rate of mortality. Therefore, significant efforts are made to develop novel strategies for the treatment of glioma. Ineffective, long-term cancer chemotherapy can lead to multidrug resistance (MDR), which is one of the most common reasons for the failure of chemotherapy. The present study investigated the effects of cytokine‑induced killer cells (CIK) on reversing MDR in cisplatin-resistant U87MG cells (U87MG/DDP). Mononuclear cells were isolated from the peripheral blood of healthy individuals and cultured in vitro in the presence of a combination of cytokines to generate CIK for the treatment of U87MG/DDP. An MTS assay, flow cytometric analysis of apoptosis, ELISA, western blotting and reverse transcription quantitative polymerase chain reaction were used to investigate the MDR-reversing effects of CIK as well as the underlying mechanisms. The results showed that cisplatin sensitivity and the apoptotic rate following cisplatin treatment were increased, P‑glycoprotein expression was decreased and the intracellular rhodamine‑123 content was increased in U87MG/DDP co‑cultured with CIK. In addition, the present study also identified increased mRNA and protein expression levels of MDR gene 1 (MDR1), MDR‑associated protein 1 (MRP1), B-cell lymphoma 2, Survivin and glutathione S-transferase‑π, while the phosphorylation of AKT and the transcriptional activity of nuclear factor‑κB in CIK co‑cultured U87MG/DDP was decreased. These results indicated that pre‑treatment with CIK reversed the MDR of U87MG/DDP, and that CIK‑induced apoptosis of U87MG/DDP was associated with the inhibition of Akt/NF‑κB. These findings suggested that treatment with CIK may be an effective method to enhance the sensitivity of patients with glioma to chemotherapy.

Melissa officinalis extract induces apoptosis and inhibits proliferation in colon cancer cells through formation of reactive oxygen species

PURPOSE

Efficient strategies for the prevention of colon cancer are extensively being explored, including dietary intervention and the development of novel phytopharmaceuticals. Safe extracts of edible plants contain structurally diverse molecules that can effectively interfere with multi-factorial diseases such as colon cancer. In this study, we describe the antiproliferative and proapoptotic effects of ethanolic lemon balm (Melissa officinalis) leaves extract in human colon carcinoma cells. We further investigated the role of extra- and intracellular reactive oxygen species (ROS).

METHODS

Antitumor effects of lemon balm extract (LBE) were investigated in HT-29 and T84 human colon carcinoma cells. Inhibition of proliferation was analyzed by DNA quantification. The causal cell cycle arrest was determined by flow cytometry of propidium iodide-stained cells and by immunoblotting of cell cycle regulator proteins. To investigate apoptosis, cleavage of caspases 3 and 7 was detected by immunoblotting and fluorescence microscopy. Phosphatidylserine externalization was measured by Annexin V assays. Mechanistic insights were gained by measurement of ROS using the indicator dyes CM-H2DCFDA and Cell ROX Green.

RESULTS

After 3 and 4 days of treatment, LBE inhibited the proliferation of HT-29 and T84 colon carcinoma cells with an inhibitory concentration (IC50) of 346 and 120 µg/ml, respectively. Antiproliferative effects were associated with a G2/M cell cycle arrest and reduced protein expression of cyclin dependent kinases (CDK) 2, 4, 6, cyclin D3, and induced expression of cyclin-dependent kinase inhibitor 2C (p18) and 1A (p21). LBE (600 µg/ml) induced cleavage of caspases 3 and 7 and phosphatidylserine externalization. LBE-induced apoptosis was further associated with formation of ROS, whereas quenching of ROS by antioxidants completely rescued the colon carcinoma cells from LBE-induced apoptosis.

CONCLUSIONS

Lemon balm (Melissa officinalis) extract inhibits the proliferation of colon carcinoma cells and induces apoptosis through formation of ROS. Taken together, LBE or subfractions thereof could be used for the prevention of colon cancer.

Exploitation of cytotoxicity of some essential oils for translation in cancer therapy

Essential oils are complex mixtures of several components endowed with a wide range of biological activities, including antiseptic, anti-inflammatory, spasmolytic, sedative, analgesic, and anesthetic properties. A growing body of scientific reports has recently focused on the potential of essential oils as anticancer treatment in the attempt to overcome the development of multidrug resistance and important side effects associated with the antitumor drugs currently used. In this review we discuss the literature on the effects of essential oils in  in vitro and in vivo models of cancer, focusing on the studies performed with the whole phytocomplex rather than single constituents.