HT-29 Human Colon Carcinoma Cells Research Articles

Interleukin-18 synergism with interleukin-2 in cytotoxicity and NKG2D expression of human natural killer cells.

Natural killer (NK) cells play an important role in anti-tumor immunity. Interleukin (IL)-18 is an immunoregulatory cytokine that induces potent NK cell-dependent anti-tumor responses when administrated with other cytokines. In this study, we explored the effects of combining IL-18 and IL-2 on NK cytotoxicity as well as expression levels of the NK cell receptor NKG2D in vitro. Freshly isolated PBMCs were incubated for 48 h with IL-18 and IL-2, then CD107a expression on CD3-CD56+ NK cells was determined by three-colour flow cytometry to evaluate the cytotoxicity of NK cells against human erythroleukemia K562 cells and human colon carcinoma HT29 cells. Flow cytometric analysis was also employed to determine NKG2D expression on NK cells. The combined use of IL-18 and IL-2 significantly increased CD107a expression on NK cells compared with using IL-18 or IL-2 alone, suggesting that the combination of these two cytokines exerted synergistic enhancement of NK cytotoxicity. IL-18 also enhanced NKG2D expression on NK cells when administered with IL-2. In addition, blockade of NKG2D signaling with NKG2D-blocking antibody attenuated the up-regulatory effect of combining IL-18 and IL-2 on NK cytolysis. Our data revealed that IL-18 synergized with IL-2 to dramatically enhance the cytolytic activity of human NK cells in a NKG2D-dependent manner. The results appear encouraging for the use of combined IL-18 and IL-2 in tumor immunotherapy.

Magnetic nanoparticles from Magnetospirillum gryphiswaldense increase the efficacy of thermotherapy in a model of colon carcinoma.

Magnetic nanoparticles (MNPs) are capable of generate heating power under the influence of alternating magnetic fields (AMF); this behaviour recently opened new scenarios for advanced biomedical applications, mainly as new promising tumor therapies. In this paper we have tested magnetic nanoparticles called magnetosomes (MNs): a class of MNPs naturally produced by magnetotactic bacteria. We extracted MNs from Magnetospirillum gryphiswaldense strain MSR-1 and tested the interaction with cellular elements and anti-neoplastic activity both in vitro and in vivo, with the aim of developing new therapeutic approaches for neoplastic diseases. In vitro experiments performed on Human Colon Carcinoma HT-29 cell cultures demonstrated a strong uptake of MNs with no evident signs of cytotoxicity and revealed three phases in the interaction: adherence, transport and accumulation in Golgi vesicles. In vivo studies were performed on subcutaneous tumors in mice; in this model MNs are administered by direct injection in the tumor volume, then a protocol consisting of three exposures to an AMF rated at 187 kHz and 23kA/m is carried out on alternate days, over a week. Tumors were monitored by Magnetic Resonance Imaging (MRI) to obtain information about MNs distribution and possible tissue modifications induced by hyperthermia. Histological analysis showed fibrous and necrotic areas close to MNs injection sites in mice subjected to a complete thermotherapy protocol. These results, although concerning a specific tumor model, could be useful to further investigate the feasibility and efficacy of protocols based on MFH. Magnetic nanoparticles naturally produced and extracted from bacteria seem to be promising candidates for theranostic applications in cancer therapy.

O1-4-5 - Effects and Functional Mechanisms of Photosan-Loaded Nanoparticle-Mediated Photodynamic Therapy on Ht29 Cells

Background: Photodynamic therapy(PDT) is a non-invasive treatment modality for selective destruction of cancer and other diseases.PDT has several potential advantages over surgery and radiotherapy, It requires three elements: a photosensitizer(PS), light and oxygen, Nanoparticles are efficient means to deliver photosensitizers for photodynamic therapy. However, it is largely unknown if Photosan-II can be efficiently delivered by hollow silica nanoparticles (HSNP). We investigated the effects and functional mechanisms of photodynamic therapy (PDT) mediated by a nanocrystallized photosensitizer (Photosan-loaded hollow silica nanoparticles) on the human colon carcinoma cell line HT29.Methods: HT29 cells were treated with nanocrystallized photosensitizer-mediated PDT, and the rate of cell survival and effects on apoptosis or cell necrosis were investigated with tetrazolium (MTT) assays and flow cytometry, respectively. We quantified the variation of Bcl-2 and Bax expression in nude mice transplanted with HT29 cells before and after PDT with quantitative reverse transcription-polymerase chain reaction (qRT-PCR).Results: MTT assays revealed that cell growth was inhibited in an obvious manner, and there was a dramatic decline in the rate of survival (P < 0.05) following PDT; flow cytometry showed predominant induction of apoptosis in PDT-treated cells. qRT-PCR revealed that PDT downregulated Bcl-2 expression with concomitant upregulation of Bax expression in HT29 cells, i.e., the Bcl-2/Bax expression ratio was decreased.Conclusion: PDT mediated by Photosan-loaded hollow silica nanoparticles inhibits the growth of human colon carcinoma HT29 cells with predominant induction of apoptosis. It can also downregulate the Bcl-2/Bax expression ratio, thereby inducing apoptosis in HT29 cells.

묵은지 스타터 Lactobacillus curvatus ML17의 생균제적 특성 및 기능성 조사

This study investigated the probiotic and functional characteristics of Mukeunji starter, Lactobacillus curvatus ML17, isolated from Mukeunji. Lb. curvatus ML17 was confirmed as a safe microorganism due to its non-hemolytic activity and non-production of harmful β-glucuronidase and β-glucosidase. Tolerance to artificial gastric and bile juice of Lb. curvatus ML17 was investigated. After incubation in artificial gastric and bile juice, the number of surviving cells was 1.38×10<SUP>8</SUP> CFU/mL. According to the results of adhesion assay, this strain also exhibited good adhesion to Caco-2 cells. Lb. curvatus ML17 showed good antimicrobial activity against food borne pathogens, especially Micrococcus luteus, Bacillus cereus, Salmonella enterica subsp. enterica, and Pseudomonas aeruginosa. Cell-free extract of Lb. curvatus ML17 exhibited high levels of DPPH scavenging capacity and inhibitory effects on growth of AGS human gastric adenocarcinoma cells and HT-29 human colon carcinoma cells. These results suggest that Lb.curvatus ML17 has potential for application in functional foods.

Development of a Thermally Responsive Nanogel Based on Chitosan–Poly(N-Isopropylacrylamide-co-Acrylamide) for Paclitaxel Delivery

A thermally responsive nanogel was developed through the radical polymerization based on chitosan (CTS) and N-isopropylacrylamide (NIPAAm) with acrylamide (AAm) blended to explore the possibility of increasing the volume phase transition temperature (VPTT). The thermally sensitive features of resultant nanogels were studied by determining variance of transmittance and changeable size. The VPTT of the CTS-poly(NIPAAm-co-AAm5.5) nanogel, coplymerized with 5.5% wt. AAm /wt. NIPAAm, was 38 °C in contrast to 32 °C of the CTS-poly(NIPAAm) polymer and the former was studied thereafter. The critical aggregation concentration of CTS-poly(NIPAAm-co-AAm5.5) nanogels was 1.11 μg/mL, much smaller than CTS-poly(NIPAAm) nanogels (5.00 μg/mL). Paclitaxel (PTX) was encapsulated in CTS-poly(NIPAAm-co-AAm5.5) nanogels with loading efficiency of about 9.06 ± 0.195% (n = 3). Thermally responsive PTX in vitro release fromPTX-loaded nanogels was verified. Coumarin-6-loaded nanogels showed thermally responsive cellular uptake because of electrostatic absorptive endocytosis. Furthermore, the half maximal inhibitory concentration of PTX-loaded nanogels was about 2.025 nmol/L, 10-fold improved relative to PTX solutions against SMMC 7721 cells. In vivo, PTX-loaded nanogels presented remarkably higher antitumor efficacy against human colon carcinoma cells HT-29 xenograft nude mice model after intravenous administration. Accordingly, our results reinforced the potential means of CTS-poly(NIPAAm-co-AAm5.5) nanogels for the combination of thermal therapy and chemotherapy.

Antimicrobial prenylated benzoylphloroglucinol derivatives and xanthones from the leaves of Garcinia goudotiana

Bioassay-guided fractionation using antimicrobial assay of the crude acetonic extract of Garcinia goudotiana leaves and of its five partitions led to the isolation of two new prenylated benzoylphloroglucinol derivatives, goudotianone 1 (1) and goudotianone 2 (2), in addition to two known compounds including one xanthone, 1,3,7-trihydroxy-2-isoprenylxanthone (3), and one triterpenoid, friedelin (4). Their structures were elucidated on the basis of different spectroscopic methods, including extensive 1D- and 2D-NMR spectroscopy and mass spectrometry. The crude acetonic extract, the methylene chloride and ethyl acetate partitions, and some tested compounds isolated from this species (1–3) demonstrated selective significant antimicrobial activities against Gram-positive bacteria, in particular Staphylococcus lugdunensis, Enterococcus faecalis and Mycobacterium smegmatis. The potential cytotoxic activities of these extracts and compounds were evaluated against human colon carcinoma HT29 and human fetal lung fibroblast MRC5 cells.

Anti-oxidative and Anti-cancer Activities by Cell Cycle Regulation of Salsola collina Extract

Salsola collina, also known as Russian thistle, is widely distributed in and around waste facilities, roadsides, and drought and semi-drought areas, and is used as a traditional folk remedy in Chinese medicine for the treatment of hypertension. In this study, we have evaluated the anti-oxidative and anti-cancer activities of the ethanol extract of S. collina Pall. (EESC), and the molecular mechanisms of its anti-cancer effects on human colon carcinoma HT29 cells. EESC exhibited anti-oxidative activity through DPPH radical scavenging capacity and showed cytotoxic activity in a dose-dependent manner in HT29 cells. After EESC treatment, HT29 cells altered their morphology, becoming smaller and irregular in shape. EESC also induced cell accumulation in the G2/M phase in a dose-dependent manner, accompanied by a decrease of cell population in the G1 phase. The G2/M arrest by EESC was associated with the increased expression of cyclin-dependent kinase (CDK) inhibitor p21 and Wee1 kinase, which phosphorylates, or inactivates, Cdc2. EESC treatment induced the phosphorylation of Cdc2 and Cdc25C, and inhibited cyclin A and Cdc25C protein expression. In addition, S arrest was induced by the highest concentration of EESC treatment, associated with a decrease of cyclin A and Cdk2 expression. These findings suggest that EESC may possess remarkable anti-oxidative activity and exert an anti-cancer effect in HT29 cells by cell cycle regulation.

Cytotoxic activity of two natural sesquiterpene lactones, isobutyroylplenolin and arnicolide D, on human colon cancer cell line HT-29

In this study, we found that two sesquiterpene lactones, isobutyroylplenolin and arnicolide D, from Centipeda minima L. (Compositae) exerted stronger cytotoxic activity than cisplatin on the human colon carcinoma HT-29 cell line. Furthermore, the cytotoxicity of these two compounds on normal cells was weaker than that of cisplatin. Treatment with isobutyroylplenolin and arnicolide D increased the levels of intracellular reactive oxygen species and decreased the levels of nuclear factor-κB protein, resulting in cell cycle arrest in G1 phase and apoptosis. We also discuss the difference in structure and activity between these two compounds.

Cytotoxic activity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves

BackgroundThe low efficacy of cancer therapy for the treatment of patients with advanced disease makes the development of new anticancer agents necessary. Because natural products are a significant source of anticancer drugs, it is important to explore cytotoxic activity of novel compounds from natural origin. PurposeThe aim of this work is to evaluate the cytotoxic capacity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves. Hirsutanone cytotoxic way of action was also studied. Material and methodsThe cytotoxic ability of Alnus glutinosa leaves ethyl acetate extract was studied over HeLa and PC-3 cell lines, with the MTT colorimetric assay. Hirsutanone was isolated from this extract using chromatographic methods, and its structure elucidated by spectroscopic analysis. HT-29 cell viability after hirsutanone treatment was determined using SRB assay. In order to understand hirsutanone way of action, cytotoxicity was evaluated adding the diarylheptanoid and antioxidants. DNA topoisomerase II (topo II) poison activity, was also evaluated using purified topo II and a supercoiled form of DNA that bears specific topo II recognition and binding region; topo II poisons stabilize normally transient DNA-topo II cleavage complexes, and lead an increased yield of linear form as a consequence of a lack of double-strand breaks rejoining. ResultsThe diarylheptanoid hirsutanone was isolated from Alnus glutinosa (L.) Gaertn. (Betulaceae) leaves extract that showed cytotoxic activity against PC-3 and HeLa cell lines. Hirsutanone showed cytotoxic activity against HT-29 human colon carcinoma cells. Pre-treatment with the antioxidants NAC (N-acetylcysteine) and MnTMPyP (Mn(III)tetrakis-(1-methyl-4-pyridyl)porthyrin) reduced this activity, suggesting that reactive oxygen species (ROS) participate in hirsutanone-induced cancer cell death. Using human topo II and a DNA supercoiled form, hirsutanone was found to stabilize topo II-DNA cleavage complexes, acting as a topo II poison. ConclusionOur data suggest that, like curcumin, an induction of oxidative stress and topo II-mediated DNA damage may play a role in hirsutanone-induced cancer cell death. Since both compounds share similar structure and cytotoxic profile, and curcumin is in clinical trials for the treatment of cancer, our results warrant further studies to evaluate the anticancer potential of hirsutanone.

Induction of Apoptosis of 2,4′,6-Trihydroxybenzophenone in HT-29 Colon Carcinoma Cell Line

2,4′,6-Trihydroxy-4-methoxybenzophenone was isolated from the ethyl acetate fraction of Phaleria macrocarpa (Scheff.) Boerl. fruits. It was found to inhibit cell proliferation in HT-29 human colon carcinoma cell line but caused little damage to WRL-68 normal human liver and MRC-5 normal human fibroblast lung cell lines. The compound was found to sharply affect the viability of HT-29 cells in a dose- and time-dependent manner. HT-29 cells treated with the compound showed morphological changes under microscopic examination such as cell shrinkage, membrane blebbing, DNA fragmentation, and the occurrence of apoptotic nuclei. The percentage of early apoptotic, late apoptotic, and dead or necrotic cells was determined by flow cytometry using annexin V-FTIC/PI staining. In addition, flow cytometry showed that, when the HT-29 cells were treated with 115 µM of the compound, it resulted in G0/G1 phase arrest in a time-dependent manner. Western blot revealed an upregulation of PUMA, Bak, Bcl-2, and Mcl-1 proteins suggesting that the compound induced apoptosis in HT-29 cells by regulating these proteins.

Induction of G2/M Arrest and Apoptosis by the Methanol Extract of Typha orientalis in Human Colon Adenocarcinoma HT29 Cells

Soojung Jin , Seung-Geun Yun , You Na Oh , Ji-Young Lee , Hyun-jin Park , Kyong-Suk Jin , Hyun Ju Kwon and Byung Woo Kim . Microbiol. Biotechnol. Lett. 2013;41:425-32. https://doi.org/10.4014/kjmb.1308.08002

Purification and Characterization of Antioxidant Peptides from Oyster (Saccostrea cucullata) Hydrolysate and the Anticancer Activity of Hydrolysate on Human Colon Cancer Cell Lines

The focus of the study was to investigate antioxidant activity and characterize antioxidant peptides from oyster (Saccostrea cucullata) protein hydrolysate. The protease hydrolysate of oyster exhibited strong potential to donate hydrogen and was able to scavenge Hydrogen peroxide, Hydroxyl and DPPH radicals. Due to the high antioxidant potential, hydrolysate was purified in Sephadex G-25 gel filtration chromatography. The active peptide fraction was further purified by UPLC-MS. Totally seven antioxidant peptides were collected. Among seven peptides (SCAP 1–7), three peptides (SCAP 1, 3 and 7) had highest scavenging ability on DPPH radicals. The amino acid sequence and molecular mass of purified antioxidant peptides (SCAP1, SCAP3 and SCAP7) were determined by Q-TOF ESI mass spectroscopy and structures of the peptides were Leu-Ala-Asn-Ala-Lys (MW = 515.29 Da), Pro-Ser-Leu-Val-Gly-Arg-Pro–Pro-Val-Gly-Lys-Leu-Thr-Leu (MW = 1,432.89 Da) and Val-Lys-Val-Leu-Leu-Glu-His-Pro-Val-Leu (MW = 1,145.75 Da), respectively. The oyster hydrolysate was tested for cell cytotoxicity on Vero (kidney epithelial cells of the African Green Monkey) and HT-29 (human colon carcinoma) cell lines. It was found that the hydrolysate did not show any cytotoxic effect for Vero cell lines and exerted a significant cytotoxic effect on HT-29 cell lines. We thus conclude that the anticancer and antioxidative hydrolysate from oyster (S. cucullata) may be useful ingredients in food and nutraceutical applications.

The inhibitory effects of a new cobalt-based polyoxometalate on the growth of human cancer cells

A new cobalt-based polyoxometalate, (Himi)2[Bi(2)W2(0)O(66)(OH)(4)Co2(H2O)(6)Na(4) (H2O)14] · 17H2O (imi = iminazole) (BWCN) has been synthesized and structurally characterized. The inhibitory activities against selected human cancer lines were also determined in this study. The cell viability and chemoresistance of BWCN on human colon carcinoma HT-29 cells were assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide), cell morphology changes, a comet assay and western blot analysis. The typical morphologic changes of apoptosis and DNA damage indicated that BWCN could have a distinct proliferation inhibitory effect on cancer cells. BWCN as a chemotherapeutic agent also induced apoptosis on HT-29 cells and showed a significant expression of cleaved-caspase-3. These results suggested that the active site of BWCN is the polymeric anion based on the basic tectonic block {BiW(9)}, and the possible mechanism is related to the interference of DNA synthesis in cancer cells.

Synthesis of 5‐Fluorouridine Nucleolipid Derivatives and Their Cytostatic/Cytotoxic Activities on Human HT‐29 Colon Carcinoma Cells

One of the major drawbacks of chemotherapeutics is their insufficient penetration through cell membranes due to a high hydrophobicity. Thus, we have synthesized a series of selected nucleolipid derivatives of 5-fluorouridine (5-FUrd; 2a), carrying lipophilic moieties at N(3) and/or in the 2',3'-O-position (i.e., 3a-7a and 3c), and tested their cytostatic/cytotoxic activities using HT-29 human colon carcinoma cells, in comparison with, e.g., 5-FU (1) and 5-FUrd (2a). Incorporation and intracellular localization of the substances under test were performed after conjugation with the fluorochrome Atto 425. We showed that all 5'-O-labelled Atto 425 derivatives were incorporated by the human HT-29 cells and accumulated in their cytoplasm. Moreover, after 24-h treatment of HT-29 human colon carcinoma cells, 1 or 2a (10, 20, 40, or 80 μM) revealed a significant (14-23 or 33-45%, resp.) decrease of the viability in comparison with the (negative) control. Interestingly, derivatives 3a and 3c (40 and 80 μM) led to a significant (77-95 or 89-96%, resp.) inhibition of survival of human HT29 cells, i.e., these two substances were ca. 63-72% or ca. 75%, respectively more effective than 5-FU (1; positive control). Furthermore, derivative 5a showed a significant, i.e., 30 and 86%, inhibition of the survival at 40 and 80 μM, respectively in comparison with the (negative) control. Some synthesized 5-FUrd derivatives turned out to be more effective than 5-FU (1) or 5-FUrd (2a).

Combined incubation of colon carcinoma cells with phorbol ester and mitochondrial uncoupling agents results in synergic elevated reactive oxygen species levels and increased γ-glutamyltransferase expression

The NADPH oxidase (NOX) is a significant determinant for the expression and activity of γ-glutamyltransferase (GGT), which is frequently upregulated after increased levels of reactive oxygen species (ROS) and oxidative stress. Earlier studies on human colon carcinoma HT-29 cells have shown that treatment with phorbol 12-myristate 13-acetate (PMA) activates NOX thus increasing the intracellular level of ROS and upregulating GGT. Another important source of cellular ROS is the mitochondria, and treatment with the mitochondria uncoupler carbonylcyanide-4-(trifluoromethoxy)-phenylhydrazone (FCCP) results in increased ROS levels. The present study shows that when HT-29 cells were simultaneously treated with both agents, a significant and synergic increase in intracellular ROS was detected. NOX activity contributed at least 50% of this increase as inhibiting NOX activity with apocynin or downregulating the NOX activity using siRNA against p22 phox reduced the synergic ROS production. The combined FCCP and PMA treatment also provoked highly increased GGT mRNA levels after 24h whereas only minor and delayed increases in GGT protein and enzyme activity levels were detected. The results strongly indicate that ROS production by both mitochondria and NOX is involved in the regulation of GGT expression in colon carcinoma cells.

Effect of the Schiff base complex diaqua-(N-salicylidene-l-glutamato)copper(II) monohydrate on human tumor cells

The aim of our study was to estimate cytostatic/cytotoxic activity of the copper(II) Schiff base complex of the composition [Cu(N-salicylidene-l-glutamato)(H2O)2]·H2O, further Cu(SG-L)H2O, against human colon carcinoma cell line HT-29, as well as to determine type of cell death and to find out the molecular mechanism of apoptosis induced by this complex. Two highest concentrations (50, 100µmol/l) of the complex showed a strong cytotoxic activity against human colon carcinoma cells HT-29 after 72h of influence. Other concentrations had a cytostatic activity. Unchelated copper(II) ions and free ligands had no effect on the cell growth. Cu(SG-L)H2O preferentially reduced cancer cell viability compared to healthy cells (NIH-3T3). Cu(SG-L)H2O induced apoptosis of cells HT-29 at all concentrations used (1–100µmol/l) after 48h of influence. Apoptosis was carried out by the mitochondrial pathway with active caspases 3 and 9. By the spin-trapping technique combined with electron paramagnetic resonance we found that our complex is photochemically stable in aqueous systems and does not exhibit radical-scavenging activity when 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) cation radical was used as an oxidant. The complex exhibits a strong prooxidant property in the initial stages of thermal decomposition of K2S2O8 in water solutions leading to the massive production of ·OH radicals. Therefore, this complex could strongly participate in anticancer action via a free radical mechanism.

Augmented cytotoxicity of hydroxycamptothecin-loaded nanoparticles in lung and colon cancer cells by chemosensitizing pharmaceutical excipients

The aim of this was to investigate and compare the chemosensitizing effect of some pharmaceutical excipients (TPGS, Pluronic P85 and chitosan) by evaluating the cytotoxicity of the chemotherapeutic drug Hydroxy Camptothecin (HCPT) loaded into PLGA nanoparticles. Different nanoparticles formulations were developed and evaluated for size, zeta potential, morphology, loading and encapsulation efficiency as well as in vitro drug release. The cytotoxicity of the nanoparticles was evaluated by MTT assay in A549 (human lung carcinoma cell line) and HT29 (human colon carcinoma cell line) whereas their cellular uptake was determined by confocal laser scanning microscopy and microfluorimetry assay. The results revealed that nanoparticles possessed a desirable nanometric size (revealed by dynamic light scattering measurements and TEM) with appreciable HCPT encapsulation (>48%) and negative surface charge that was switched to positive upon coating with chitosan. The nanoparticles adopted a sustained release phase preceded by initial burst of HCPT that was reduced by chitosan coating. The cytotoxicity of the nanoparticles in A549 and HT29 cells was significantly augmented compared to simple drug solution and basic nanoparticles without excipients. The excipients could be ranked according to their IC50 lowering effect in the following order [TPGS (sixfold lower IC50) > Pluronic P85 > Chitosan]. The augmented cytotoxicity and chemosensitizing effect might be attributed to overcoming drug efflux (in case of TPGS 1000 or Pluronic P85) and/or maximizing internalization by cancer cells (chitosan coating). Acting as chemopotentiators, the studied excipients could have potential in reducing therapeutic HCPT doses and minimizing adverse effects in lung and colon chemotherapy.

Evaluation of Opuntia spp. derived products as antiproliferative agents in human colon cancer cell line (HT29)

During the last years, special interest has been focused on the recovery of bioactive compounds from food industry wastes in an effort to find added value applications for residues. In this work, Opuntia spp. residues from fruit juice production were explored as potential sources of natural chemotherapeutic ingredients towards colon cancer. Hydroalcoholic extraction and adsorption separation processes (with Amberlite XAD16 resin) were used to produce natural extracts from residues of Opuntia ficus-indica and Opuntia robusta and their antiproliferative effect was evaluated in human colon carcinoma HT29 cell line. Our results showed that the natural extracts efficiently inhibited cancer cell growth and induced cell cycle arrest in different checkpoints—G1, G2/M and S. The phytochemical constituents presented in the samples, namely betacyanins, flavonoids (isorhamnetin derivatives) and phenolic acids (ferulic acid) were identified as the main responsible compounds for the cell cycle arrest. Moreover, the extracts that presented the lowest effective dose values in terms of polyphenols (ED50 value<0.5mgGAE/mL) showed to increase intracellular ROS accumulation in HT29 cells, suggesting that cancer cell death may be induced by the pro-oxidant effect of these compounds.

Cytotoxic and anti-inflammatory effects of onion peel extract on lipopolysaccharide stimulated human colon carcinoma cells

The present study investigated the cytotoxic activity of ethanol extract of onion peel (OPE) in HT-29 human colon carcinoma cells. High-performance liquid chromatography (HPLC) analysis was performed to determine the amounts of phenolic acids and flavonoids in OPE. In addition, the influence of OPE on antioxidant- and inflammation-associated gene expression was also determined in a model of lipopolysaccharide (LPS)-stimulated HT-29 cells. HPLC analysis showed that OPE contained well-known antioxidant compounds, including p-coumaric acid, vanillic acid, epicatechin, and morin. After incubation with OPE, HT-29 cells showed either a loss of normal nuclear architecture or detachability from each other. The cytotoxic effects of OPE on HT-29 cells were confirmed by MTT and LDH release assays. LPS-induced oxidative conditions effectively downregulated TNF-α mRNA expression in OPE pretreated HT-29 cells compared with cells only stimulated with LPS. In addition, the expression of heme oxygenase-1 (HO-1) and glutathione S-transferase (GSTs) detoxification genes (i.e., GSTM1, GSTT1, and GSTP1) was upregulated after treatment with LPS at sublethal concentrations. However, the LPS-induced mRNA expression of HO-1 and GSTs was significantly attenuated by treatment with OPE. Therefore, onion peel extract is a promising component of future nutraceuticals and value-added products.

Delphinidin is a novel inhibitor of lymphangiogenesis but promotes mammary tumor growth and metastasis formation in syngeneic experimental rats

We have recently demonstrated that the anthocyanidin delphinidin (DEL), one of the most abundant dietary flavonoids, inhibits activation of ErbB and vascular endothelial growth factor receptor family members. These receptors play crucial roles in the context of tumor progression and the outgrowth of blood and lymphatic vessels. Here, we have developed an improved chemical synthesis for DEL in order to study the effects of the aglycon and its degradation product gallic acid (GA) on endothelial and tumor cells in vitro and in vivo. We found that DEL blocked the proliferation in vitro of primary human blood and lymphatic endothelial cells as well as human HT29 colon and rat MT-450 mammary carcinoma cells in a dose-dependent manner. In contrast, its degradation product GA had little effect. At higher concentrations, DEL induced apoptosis of endothelial and tumor cells. Furthermore, DEL potently blocked the outgrowth of lymphatic capillaries in ex vivo lymphangiogenesis assays. In the MT-450 rat syngeneic breast tumor model, it also significantly reduced angiogenesis and tumor-induced lymphangiogenesis when administered in vivo. These data reveal DEL to be a novel antilymphangiogenesis reagent. Surprisingly, however, the application of DEL unexpectedly promoted tumor growth and metastasis in the MT-450 tumor model, suggesting that the antiproliferative effect of DEL on cultured cells does not necessarily reflect the response of tumors to this anthocyanidin in vivo. Furthermore, while DEL may have utility as a cancer chemopreventative agent, its ability to promote tumor growth once a neoplasm develops also needs to be taken into consideration.