Update on the Anti-Cancer Potency of Tocotrienols and α-Tocopheryl Polyethylene Glycol 1000 Succinate on Leukemic Cell Lines.

The natural isoforms of vitamin E γ-tocotrienol (γ-ΤΤ) and δ-tocotrienol (δ-ΤΤ) and the synthetic derivative α-tocopheryl polyethylene glycol 1000 succinate (TPGS) have promising anticancer potency in a variety of cancer cell lines and animal models of cancer. Ongoing clinical trials are investigating the anti-tumor effectiveness of TTs in combination with chemotherapeutic agents in patients suffering from breast, colon, non-small cell lung and ovarian cancers. Despite extensive research on different types of cancer, the anticancer potency of TTs and TPGS has not been thoroughly investigated in leukemias. Given the fact that certain types of leukemias have very low survival rates and that patients suffer significantly from the toxic side effects of chemotherapeutic drugs, there is a need to develop novel treatments with increased specificity against cancer cells and reduced toxicity to the patients. The aim of this review is to report current evidence on the anticancer potency of TTs and TPGS on leukemic cells lines and to discuss future studies that could be carried out to investigate the role of these agents in the management of leukemias.

Anti-Cancer Activity and Phenolic Content of Extracts Derived from Cypriot Carob (Ceratonia siliqua L.) Pods Using Different Solvents.

Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due to the presence of polyphenolic compounds. In this study, we explored, for the first time, the anti-cancer properties of Cypriot carobs. We produced extracts from ripe and unripe whole carobs, pulp and seeds using solvents with different polarities. We measured the ability of the extracts to inhibit proliferation and induce apoptosis in cancer and normal immortalized breast cells, using the MTT assay, cell cycle analysis and Western Blotting. The extracts' total polyphenol content and anti-oxidant action was evaluated using the Folin-Ciocalteu method and the DPPH assay. Finally, we used LC-MS analysis to identify and quantify polyphenols in the most effective extracts. Our results demonstrate that the anti-proliferative capacity of carob extracts varied with the stage of carob maturity and the extraction solvent. The Diethyl-ether and Ethyl acetate extracts derived from the ripe whole fruit had high Myricetin content and also displayed specific activity against cancer cells. Their mechanism of action involved caspase-dependent and independent apoptosis. Our results indicate that extracts from Cypriot carobs may have potential uses in the development of nutritional supplements and pharmaceuticals.

6-O-(3″, 4″-di-O-trans-cinnamoyl)-α-l-rhamnopyranosylcatalpol and verbascoside: Cytotoxicity, cell cycle kinetics, apoptosis, and ROS production evaluation in tumor cells.

The aim of this study was to evaluate the impact that 6-O-(3″, 4″-di-O-trans-cinnamoyl)-α- l-rhamnopyranosylcatalpol (Dicinn) and verbascoside (Verb), two compounds simultaneously reported in Verbascum ovalifolium, have on tumor cell viability, apoptosis, cell cycle kinetics, and intracellular reactive oxygen species (ROS) level. At 100 µg/mL and 48 hours incubation time, Dicinn and Verb produced good cytotoxic effects in A549, HT-29, and MCF-7 cells. Dicinn induced cell-cycle arrest at the G0 /G1 phase and apoptosis, whereas Verb increased the population of subG1 cells and cell apoptosis rates. Furthermore, the two compounds exhibited time-dependent ROS generating effects in tumor cells (1-24 hours). Importantly, no cytotoxic effects were induced in nontumor MCF-10A cells by the two compounds up to 100 µg/mL. Overall, the effects exhibited by Verb in tumor cells were more potent, which can be correlated with its structural features, such as the presence of phenolic hydroxyl groups.

Yeast GPCR signaling reflects the fraction of occupied receptors, not the number.

According to receptor theory, the effect of a ligand depends on the amount of agonist-receptor complex. Therefore, changes in receptor abundance should have quantitative effects. However, the response to pheromone in Saccharomyces cerevisiae is robust (unaltered) to increases or reductions in the abundance of the G-protein-coupled receptor (GPCR), Ste2, responding instead to the fraction of occupied receptor. We found experimentally that this robustness originates during G-protein activation. We developed a complete mathematical model of this step, which suggested the ability to compute fractional occupancy depends on the physical interaction between the inhibitory regulator of G-protein signaling (RGS), Sst2, and the receptor. Accordingly, replacing Sst2 by the heterologous hsRGS4, incapable of interacting with the receptor, abolished robustness. Conversely, forcing hsRGS4:Ste2 interaction restored robustness. Taken together with other results of our work, we conclude that this GPCR pathway computes fractional occupancy because ligand-bound GPCR-RGS complexes stimulate signaling while unoccupied complexes actively inhibit it. In eukaryotes, many RGSs bind to specific GPCRs, suggesting these complexes with opposing activities also detect fraction occupancy by a ratiometric measurement. Such complexes operate as push-pull devices, which we have recently described.

Selective activation of TNFR1 and NF-κB inhibition by a novel biyouyanagin analogue promotes apoptosis in acute leukemia cells.

BACKGROUND: Acquired resistance towards apoptosis is a hallmark of cancer. Elimination of cells bearing activated oncogenes or stimulation of tumor suppressor mediators may provide a selection pressure to overcome resistance. KC-53 is a novel biyouyanagin analogue known to elicit strong anti-inflammatory and anti-viral activity. The current study was designed to evaluate the anticancer efficacy and molecular mechanisms of KC-53 against human cancer cells. METHODS: Using the MTT assay we examined initially how KC-53 affects the proliferation rates of thirteen representative human cancer cell lines in comparison to normal peripheral blood mononuclear cells (PBMCs) and immortalized cell lines. To decipher the key molecular events underlying its mode of action we selected the human promyelocytic leukemia HL-60 and the acute lymphocytic leukemia CCRF/CEM cell lines that were found to be the most sensitive to the antiproliferative effects of KC-53. RESULTS: KC-53 promoted rapidly and irreversibly apoptosis in both leukemia cell lines at relatively low concentrations. Apoptosis was characterized by an increase in membrane-associated TNFR1, activation of Caspase-8 and proteolytic inactivation of the death domain kinase RIP1 indicating that KC-53 induced mainly the extrinsic/death receptor apoptotic pathway. Regardless, induction of the intrinsic/mitochondrial pathway was also achieved by Caspase-8 processing of Bid, activation of Caspase-9 and increased translocation of AIF to the nucleus. FADD protein knockdown restored HL-60 and CCRF/CEM cell viability and completely blocked KC-53-induced apoptosis. Furthermore, KC-53 administration dramatically inhibited TNFα-induced serine phosphorylation on TRAF2 and on IκBα hindering therefore p65/NF-κΒ translocation to nucleus. Reduced transcriptional expression of pro-inflammatory and pro-survival p65 target genes, confirmed that the agent functionally inhibited the transcriptional activity of p65. CONCLUSIONS: Our findings demonstrate, for the first time, the selective anticancer properties of KC-53 towards leukemic cell lines and provide a detailed understanding of the molecular events underlying its dual anti-proliferative and pro-apoptotic properties. These results provide new insights into the development of innovative and targeted therapies for the treatment of some forms of leukemia.

Targeting IL13Ralpha2 activates STAT6-TP63 pathway to suppress breast cancer lung metastasis.

INTRODUCTION: Basal-like breast cancer (BLBC) is an aggressive subtype often characterized by distant metastasis, poor patient prognosis, and limited treatment options. Therefore, the discovery of alternative targets to restrain its metastatic potential is urgently needed. In this study, we aimed to identify novel genes that drive metastasis of BLBC and to elucidate the underlying mechanisms of action. METHODS: An unbiased approach using gene expression profiling of a BLBC progression model and in silico leveraging of pre-existing tumor transcriptomes were used to uncover metastasis-promoting genes. Lentiviral-mediated knockdown of interleukin-13 receptor alpha 2 (IL13Ralpha2) coupled with whole-body in vivo bioluminescence imaging was performed to assess its role in regulating breast cancer tumor growth and lung metastasis. Gene expression microarray analysis was followed by in vitro validation and cell migration assays to elucidate the downstream molecular pathways involved in this process. RESULTS: We found that overexpression of the decoy receptor IL13Ralpha2 is significantly enriched in basal compared with luminal primary breast tumors as well as in a subset of metastatic basal-B breast cancer cells. Importantly, breast cancer patients with high-grade tumors and increased IL13Ralpha2 levels had significantly worse prognosis for metastasis-free survival compared with patients with low expression. Depletion of IL13Ralpha2 in metastatic breast cancer cells modestly delayed primary tumor growth but dramatically suppressed lung metastasis in vivo. Furthermore, IL13Ralpha2 silencing was associated with enhanced IL-13-mediated phosphorylation of signal transducer and activator of transcription 6 (STAT6) and impaired migratory ability of metastatic breast cancer cells. Interestingly, genome-wide transcriptional analysis revealed that IL13Ralpha2 knockdown and IL-13 treatment cooperatively upregulated the metastasis suppressor tumor protein 63 (TP63) in a STAT6-dependent manner. These observations are consistent with increased metastasis-free survival of breast cancer patients with high levels of TP63 and STAT6 expression and suggest that the STAT6-TP63 pathway could be involved in impairing metastatic dissemination of breast cancer cells to the lungs. CONCLUSION: Our findings indicate that IL13Ralpha2 could be used as a promising biomarker to predict patient outcome and provide a rationale for assessing the efficacy of anti-IL13Ralpha2 therapies in a subset of highly aggressive basal-like breast tumors as a strategy to prevent metastatic disease.

Vernonia kotschyana roots: therapeutic potential via antioxidant activity.

The roots of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae) are used in Malian traditional medicine in the treatment of gastroduodenal ulcers and gastritis. Since oxidative stress is involved in gastric ulceration, the aim of this study was to screen the root extracts for their in vitro antioxidant activity and phenolic content. The roots were extracted successively with chloroform, ethyl acetate, ethanol and water. The antioxidant activity of root extracts was evaluated in both cell-free and cell-based assays. Their chemical characterization was performed by Fourier transform infrared spectroscopy (FT-IR) whereas the total phenolic content was determined by the Folin-Ciocalteu method. The ethyl acetate extract displayed the highest phenolic content and was found to be the most active in the free radical scavenging and lipid peroxidation inhibition assays; it also showed a high antioxidant activity in MCF-12F cells. This study suggests a potential use of the ethyl acetate extract of Vernonia kotschyana not only as an antioxidant agent in gastroduodenal ulcers and gastritis, but also in other disorders characterized by high levels of oxidative stress.

Equol enhances tamoxifen's anti-tumor activity by induction of caspase-mediated apoptosis in MCF-7 breast cancer cells.

BACKGROUND: Soy phytoestrogens, such as daidzein and its metabolite equol, have been proposed to be responsible for the low breast cancer rate in Asian women. Since the majority of estrogen receptor positive breast cancer patients are treated with tamoxifen, the basic objective of this study is to determine whether equol enhances tamoxifen's anti-tumor effect, and to identify the molecular mechanisms involved. METHODS: For this purpose, we examined the individual and combined effects of equol and tamoxifen on the estrogen-dependent MCF-7 breast cancer cells using viability assays, annexin-V/PI staining, cell cycle and western blot analysis. RESULTS: We found that equol (>50 µM) and 4-hydroxy-tamoxifen (4-OHT; >100 nM) significantly reduced the MCF-7 cell viability. Furthermore, the combination of equol (100 µM) and 4-OHT (10 µM) induced apoptosis more effectively than each compound alone. Subsequent treatment of MCF-7 cells with the pan-caspase inhibitor Z-VAD-FMK inhibited equol- and 4-OHT-mediated apoptosis, which was accompanied by PARP and α-fodrin cleavage, indicating that apoptosis is mainly caspase-mediated. These compounds also induced a marked reduction in the bcl-2:bax ratio, which was accompanied by caspase-9 and caspase-7 activation and cytochrome-c release to the cytosol. Taken together, these data support the notion that the combination of equol and tamoxifen activates the intrinsic apoptotic pathway more efficiently than each compound alone. CONCLUSIONS: Consequently, equol may be used therapeutically in combination treatments and clinical studies to enhance tamoxifen's effect by providing additional protection against estrogen-responsive breast cancers.

rcell2: Microscopy-Based Cytometry in R.

This article describes a method for quantifying various cellular features (e.g., volume, curvature, total and sub-cellular fluorescence localization) of individual cells from sets of microscope images, and for tracking them over time-course microscopy experiments. One purposely defocused transmission image (sometimes referred to as bright-field or BF) is used to segment the image and locate each cell. Fluorescence images (one for each of the color channels or z-stacks to be analyzed) may be acquired by conventional wide-field epifluorescence or confocal microscopy. This method uses a set of R packages called rcell2. Relative to the original release of Rcell (Bush et al., 2012), the updated version bundles, into a single software suite, the image-processing capabilities of Cell-ID, offers new data analysis tools for cytometry, and relies on the widely used data analysis and visualization tools of the statistical programming framework R. © 2023 Wiley Periodicals LLC. Basic Protocol: Extracting quantitative information from single cells Support Protocol 1: Obtaining and installing Cell-ID and R Support Protocol 2: Preparing cells for imaging.

Dynamic monitoring of PD-L1 and Ki67 in circulating tumor cells of metastatic non-small cell lung cancer patients treated with pembrolizumab.

Programmed cell death protein ligand-1 (PD-L1) expression in non-small cell lung cancer (NSCLC) tumors guides treatment selection. PD-L1 expression in circulating tumor cells (CTCs) may provide further information. We have explored PD-L1 and marker of proliferation Ki-67 (Ki67; also known as MKI67) in CTCs in longitudinal samples of 47 advanced NSCLC patients receiving pembrolizumab. A triple immunofluorescence, against cytokeratin, PD-L1, and Ki67, was performed on peripheral blood mononuclear cells, at baseline, post-first cycle, post-third, and primary resistance (PMR). Patients displaying PMR (progression at first evaluation) were classified as progressive disease (PD) and those with clinical benefit as disease control (DC). CTCs were categorized as PD-L1high/low/medium/negative and Ki67+ or Ki67- . CTC evaluation revealed a significant increase in the PD-L1low CTC rate at PMR compared to baseline (2.5% at baseline vs. 36.5% at PMR), whereas a reduction in the PD-L1high CTC rate was observed (31.5% vs. 0%, respectively). Investigation of CTC status between PD and DC patients showed that PD patients more frequently increased total and PD-L1low CTCs after first cycle compared to DC (83% of PD vs. 37% of DC and 67% of PD vs. 8% of DC, respectively). Progression-free survival (PFS) was longer in patients with decreased total and PD-L1low CTCs after first cycle compared to those with increased CTCs (median PFS: not reached vs. 2 months). PD-L1+ patients presenting a high Ki67 index (% Ki67+ CTCs > 30%) before treatment had a shorter PFS compared to those with a low Ki67 (≤ 30%), and overall survival (OS) was shorter in PD-L1+ patients harboring Ki67+ CTCs compared to those not presenting (median OS: 11.8 months vs. 33.1 months, respectively). In sequential samples of patients with a durable benefit, a low Ki67 index was observed. Our results suggest that monitoring PD-L1 and Ki67 expression in CTCs of NSCLC patients treated with pembrolizumab may be predictive for pembrolizumab efficacy.

Induction of discrete apoptotic pathways by bromo-substituted indirubin derivatives in invasive breast cancer cells.

Indirubin derivatives gained interest in recent years for their anticancer and antimetastatic properties. The objective of the present study was to evaluate and compare the anticancer properties of the two novel bromo-substituted derivatives 6-bromoindirubin-3'-oxime (6BIO) and 7-bromoindirubin-3'-oxime (7BIO) in five different breast cancer cell lines. Cell viability assays identified that 6BIO and 7BIO are most effective in preventing the proliferation of the MDA-MB-231-TXSA breast cancer cell line from a total of five breast cancer cell lined examined. In addition it was found that the two compounds induce apoptosis via different mechanisms. 6BIO induces caspase-dependent programmed cell death through the intrinsic (mitochondrial) caspase-9 pathway. 7BIO up-regulates p21 and promotes G(2)/M cell cycle arrest which is subsequently followed by the activation of two different apoptotic pathways: (a) a pathway that involves the upregulation of DR4/DR5 and activation of caspase-8 and (b) a caspase independent pathway. In conclusion, this study provides important insights regarding the molecular pathways leading to cell cycle arrest and apoptosis by two indirubin derivatives that can find clinical applications in targeted cancer therapeutics.

Natural colonization and adaptation of a mosquito species in Galapagos and its implications for disease threats to endemic wildlife.

Emerging infectious diseases of wildlife have been recognized as a major threat to global biodiversity. Endemic species on isolated oceanic islands, such as the Galápagos, are particularly at risk in the face of introduced pathogens and disease vectors. The black salt-marsh mosquito (Aedes taeniorhynchus) is the only mosquito widely distributed across the Galápagos Archipelago. Here we show that this mosquito naturally colonized the Galápagos before the arrival of man, and since then it has evolved to represent a distinct evolutionary unit and has adapted to habitats unusual for its coastal progenitor. We also present evidence that A. taeniorhynchus feeds on reptiles in Galápagos in addition to previously reported mammal and bird hosts, highlighting the important role this mosquito might play as a bridge-vector in the transmission and spread of extant and newly introduced diseases in the Galápagos Islands. These findings are particularly pertinent for West Nile virus, which can cause significant morbidity and mortality in mammals (including humans), birds, and reptiles, and which recently has spread from an introductory focus in New York to much of the North and South American mainland and could soon reach the Galápagos Islands. Unlike Hawaii, there are likely to be no highland refugia free from invading mosquito-borne diseases in Galápagos, suggesting bleak outcomes to possible future pathogen introduction events.

Resveratrol loaded polymeric micelles for theranostic targeting of breast cancer cells.

Treatment of breast cancer underwent extensive progress in recent years with molecularly targeted therapies. However, non-specific pharmaceutical approaches (chemotherapy) persist, inducing severe side-effects. Phytochemicals provide a promising alternative for breast cancer prevention and treatment. Specifically, resveratrol (res) is a plant-derived polyphenolic phytoalexin with potent biological activity but displays poor water solubility, limiting its clinical use. Here we have developed a strategy for delivering res using a newly synthesized nano-carrier with the potential for both diagnosis and treatment. Methods: Res-loaded nanoparticles were synthesized by the emulsion method using Pluronic F127 block copolymer and Vitamin E-TPGS. Nanoparticle characterization was performed by SEM and tunable resistive pulse sensing. Encapsulation Efficiency (EE%) and Drug Loading (DL%) content were determined by analysis of the supernatant during synthesis. Nanoparticle uptake kinetics in breast cancer cell lines MCF-7 and MDA-MB-231 as well as in MCF-10A breast epithelial cells were evaluated by flow cytometry and the effects of res on cell viability via MTT assay. Results: Res-loaded nanoparticles with spherical shape and a dominant size of 179±22 nm were produced. Res was loaded with high EE of 73±0.9% and DL content of 6.2±0.1%. Flow cytometry revealed higher uptake efficiency in breast cancer cells compared to the control. An MTT assay showed that res-loaded nanoparticles reduced the viability of breast cancer cells with no effect on the control cells. Conclusions: These results demonstrate that the newly synthesized nanoparticle is a good model for the encapsulation of hydrophobic drugs. Additionally, the nanoparticle delivers a natural compound and is highly effective and selective against breast cancer cells rendering this type of nanoparticle an excellent candidate for diagnosis and therapy of difficult to treat mammary malignancies.

GPCR receptor phosphorylation and endocytosis are not necessary to switch polarized growth between internal cues during pheromone response in S. cerevisiae.

Chemotactic/chemotropic cells follow accurately the direction of gradients of regulatory molecules. Many G-protein-coupled receptors (GPCR) function as chemoattractant receptors to guide polarized responses. In "a" mating type yeast, the GPCR Ste2 senses the α-cell's pheromone. Previously, phosphorylation and trafficking of this receptor have been implicated in the process of gradient sensing, where cells dynamically correct growth. Correction is often necessary since yeast have intrinsic polarity sites that interfere with a correct initial gradient decoding. We have recently showed that when actively dividing (not in G1) yeast are exposed to a uniform pheromone concentration, they initiate a pheromone-induced polarization next to the mother-daughter cytokinesis site. Then, they reorient their growth to the intrinsic polarity site. Here, to study if Ste2 phosphorylation and internalization are involved in this process, we generated receptor variants combining three types of mutated signals for the first time: phosphorylation, ubiquitylation and the NPFX1,2D Sla1-binding motif. We first characterized their effect on endocytosis and found that these processes regulate internalization in a more complex manner than previously shown. Interestingly, we showed that receptor phosphorylation can drive internalization independently of ubiquitylation and the NPFX1,2D motif. When tested in our assays, cells expressing either phosphorylation or endocytosis-deficient receptors were able to switch away from the cytokinesis site to find the intrinsic polarity site as efficiently as their WT counterparts. Thus, we conclude that these processes are not necessary for the reorientation of polarization.

VL30 retrotransposition is associated with induced EMT, CSC generation and tumorigenesis in HC11 mouse mammary stem­like epithelial cells.

Retrotransposons copy their sequences via an RNA intermediate, followed by reverse transcription into cDNA and random insertion, into a new genomic locus. New retrotransposon copies may lead to cell transformation and/or tumorigenesis through insertional mutagenesis. Methylation is a major defense mechanism against retrotransposon RNA expression and retrotransposition in differentiated cells, whereas stem cells are relatively hypo­methylated. Epithelial­to­mesenchymal transition (EMT), which transforms normal epithelial cells into mesenchymal­like cells, also contributes to tumor progression and tumor metastasis. Cancer stem cells (CSCs), a fraction of undifferentiated tumor­initiating cancer cells, are reciprocally related to EMT. In the present study, the outcome of long terminal repeat (LTR)­Viral­Like 30 (VL30) retrotransposition was examined in mouse mammary stem­like/progenitor HC11 epithelial cells. The transfection of HC11 cells with a VL30 retrotransposon, engineered with an EGFP­based retrotransposition cassette, elicited a higher retrotransposition frequency in comparison to differentiated J3B1A and C127 mouse mammary cells. Fluorescence microscopy and PCR analysis confirmed the specificity of retrotransposition events. The differentiated retrotransposition­positive cells retained their epithelial morphology, while the respective HC11 cells acquired mesenchymal features associated with the loss of E­cadherin, the induction of N­cadherin, and fibronectin and vimentin protein expression, as well as an increased transforming growth factor (TGF)­ß1, Slug, Snail­1 and Twist mRNA expression. In addition, they were characterized by cell proliferation in low serum, and the acquisition of CSC­like properties indicated by mammosphere formation under anchorage­independent conditions. Mammospheres exhibited an increased Nanog and Oct4 mRNA expression and a CD44+/CD24­/low antigenic phenotype, as well as self­renewal and differentiation capacity, forming mammary acini­like structures. DNA sequencing analysis of retrotransposition­positive HC11 cells revealed retrotransposed VL30 copies integrated at the vicinity of EMT­, cancer type­ and breast cancer­related genes. The inoculation of these cells into Balb/c mice produced cytokeratin­positive tumors containing pancytokeratin­positive cells, indicative of cell invasion features. On the whole, the findings of the present study demonstrate, for the first time, to the best of our knowledge, that stem­like epithelial HC11 cells are amenable to VL30 retrotransposition associated with the induction of EMT and CSC generation, leading to tumorigenesis.

Phenoxodiol, an anticancer isoflavene, induces immunomodulatory effects in vitro and in vivo.

Phenoxodiol (PXD) is a synthetic analogue of the plant isoflavone genistein with improved anticancer efficacy. Various properties and mechanisms of action have been attributed to the drug, the most important being its ability to sensitize resistant tumour cells to chemotherapy, which led to its fast track FDA approval for phase II/III clinical trials. In this study, we examined the effects of PXD on human peripheral blood mononuclear cells (PBMC) and its potential role in regulating immune responses. We show that PXD, at concentrations >or=1 microg/ml (4 microM), inhibited proliferation and reduced the viability of healthy donor-derived PBMC. In contrast, lower PXD concentrations (0.05-0.5 microg/ml) augmented, upon 3-day incubation, PBMC cytotoxicity. Experiments with purified CD56(+) lymphocytes revealed that PXD enhanced the lytic function of natural killer (NK) cells by directly stimulating this lymphocytic subpopulation. Furthermore, in an in vivo colon cancer model, Balb/C mice administered low-dose PXD, exhibited significantly reduced tumour growth rates and prolonged survival (in 40% of the animals). Ex vivo results showed that PXD stimulated both NK and tumour-specific cell lytic activity. We conclude that PXD, when administered at low concentrations, can act as an immunomodulator, enhancing impaired immune responses, often seen in cancer-bearing individuals.

Induction of caspase-independent programmed cell death by vitamin E natural homologs and synthetic derivatives.

Current observations in the literature suggest that vitamin E may be a suitable candidate for cancer chemotherapy. To investigate this further, we examined the ability of the vitamin E natural homologs [alpha-, beta-, gamma-, delta-tocopherols (alpha-TOC, beta-TOC, gamma-TOC, delta-TOC) and alpha-, beta-, gamma-, delta-tocotrienols (alpha-TT, beta-TT, gamma-TT, delta-TT)] and their corresponding succinate synthetic derivatives [alpha-, beta-, gamma-, delta-tocopheryl succinates and alpha-, beta-, gamma-, delta-tocotrienyl succinates (alpha-TS, beta-TS, gamma-TS, delta-TS)] to induce cell death in AR- (DU145 and PC3) and AR+ (LNCaP) prostate cancer cell lines. The most effective of all the natural homologs of vitamin E was determined to be delta-TT, whereas delta-TS was the most potent of all the natural and synthetic compounds of vitamin E examined. Both gamma-TT and delta-TT induced caspase activity selectively in AR+ LNCaP cells, suggesting a possible role for AR for the activation of caspase-dependent programmed cell death (CD-PCD). More important, however, gamma-TT, delta-TT, gamma-TS, and delta-TS activated dominant caspase-independent programmed cell death (CI-PCD) in all prostate cancer cell lines examined. Thus, vitamin E homologs and synthetic derivatives may find applications in the treatment of prostate tumors that are resistant to caspase-activating therapeutic agents.

d-a-Tocopheryl Polyethylene Glycol 1000 Succinate and a small-molecule Survivin suppressant synergistically induce apoptosis in SKBR3 breast cancer cells.

Breast cancer is the second in mortality rate malignancy among women. Despite the many advances in breast cancer treatment, there is still a need to improve drug efficacy and reduce non-specific effects. D-alpha-tocopheryl polyethylene glycol succinate (TPGS) is frequently used in the development of drug delivery systems to improve the pharmacokinetics of anti-cancer drugs and reduce multi-drug resistance. We have previously shown that TPGS not only acts as a carrier molecule but also exerts anti-cancer effects. As part of this study, we investigated the effect of TPGS with YM155, a small molecule suppressant of Survivin, in various breast cancer cell lines representing different subtypes of the disease. We aimed to evaluate the presumed synergistic effect of the TPGS-YM155 combination and reveal its mechanism of action. Our results show that the TPGS-YM155 combination acts synergistically to reduce specifically the viability of SKBR3 cells. The combination of these agents reduced activation of the AKT pathway, decreased Survivin and Bcl-2 levels, and induced caspase-dependent and independent apoptosis via the mitochondrial pathway. Importantly, the TPGS-YM155 combination did not significantly affect the viability of MCF-10A normal immortalized cells. In conclusion, the combination of YM155 and TPGS could be a promising approach against SKBR3-type breast cancer.

Unravelling the potential of seaweeds from the Black Sea coast of Romania as bioactive compounds sources. Part I: Cystoseira barbata (Stackhouse) C. Agardh.

The Romanian coastlines of the Black Sea have abundant seaweed resources, but little effort has been done to investigate their biological potential. The aim of the present study was to assess the in vitro antioxidant and anti-proliferative effects of Cystoseira barbata (Stackhouse) C. Agardh (Sargassaceae), a brown alga inhabiting the Black Sea coast of Romania. The 70% acetone, methanol and water extracts of C. barbata were evaluated for their total phenolic content, antioxidant activity and anti-proliferative potential against human tumor cell lines (pulmonary A549, colon HT-29, mammary MCF-7) and the non-tumor mammary epithelial MCF-10A cell line. C. barbata 70% acetone extract (CBAE) displayed the highest antioxidant and cytotoxic activities. The mechanism of CBAE anti-proliferative activity involved initially increased intracellular ROS accumulation, followed by increased DNA content in the subG1 phase and DNA fragmentation leading to excessive apoptosis. Thus, our study provides a theoretical basis for the use of CBAE as a tumor preventive agent. Furthermore, UHPLC-DAD-QTOF-MS analysis of CBAE tentatively identified 18 phlorotannins as fucophlorethol and eckol derivatives, containing three up to seven phloroglucinol units. In conclusion, C. barbata represents a valuable source for the development of macroalgal-based products with putative use as nutraceuticals and pharmaceuticals.

Vitamin E and cancer: An insight into the anticancer activities of vitamin E isomers and analogs.

Current observations in the literature suggest that vitamin E may be a suitable candidate for the adjuvant treatment of cancer. Even though historically most research focused on alpha-tocopherol, more recent evidence suggests that the other isomers of vitamin E (beta-, gamma- and delta-tocopherols and alpha-, beta-, gamma- and delta-tocotrienols) differ in their proapoptotic potencies. The main focus of this communication is the current understanding of the molecular mechanisms regulated by vitamin E isomers and their analogs during the induction of apoptosis. This review highlights that the mitochondria are the major target for the induction of apoptosis by vitamin E isomers and analogs and that the various signaling pathways regulated by these agents are likely to contribute towards maximizing the intrinsic pathway of apoptosis triggered initially by the mitochondria. Overall, the presentation of recent studies from the literature in this communication allows the drawing of the following important conclusions: (i) no direct link exists between the antioxidant activity of each isomer/derivative and proapoptotic potency, (ii) tocotrienols are more effective proapoptotic agents than tocopherols, (iii) synthetic modifications of the naturally occurring compounds may improve their apoptotic potency and (iv) vitamin E isomers and derivatives regulate caspase-independent pathways of apoptosis. The latter combined with the evidence presented in this review regarding the additive or synergistic anticarcinogenic effects obtained when vitamin E analogs are used in combination with other cancer chemotherapeutic agents, supports further research to design the most promising vitamin E derivatives and clinically test them in adjuvant chemotherapeutic treatments.