A novel bis-benzylidenecyclopentanone derivative, BPR0Y007, inducing a rapid caspase activation involving upregulation of Fas (CD95/APO-1) and wild-type p53 in human oral epidermoid carcinoma cells

Dichloromethane fraction from Gardenia jasminoides: DNA topoisomerase 1 inhibition and oral cancer cell death induction

CONTEXT

A growing body of evidence shows that compounds of plant origin have the ability to prevent cancer. The fruit of gardenia, Gardenia jasminoides Ellis (Rubiaceae), has long been used as a food additive and herbal medicine, and its pharmacological actions, such as protective activity against oxidative damage, cytotoxic effect, and anti-inflammatory and anti-tumor activity, have already been reported.

OBJECTIVE

The purpose of the present study was to investigate the presence of DNA topoisomerase 1 inhibitor in various solvent fractions of Gardenia extract and examine the induction of oral cancer cell death upon treatment with Gardenia extract.

MATERIALS AND METHODS

The methanol extract of Gardenia was partitioned with n-hexane, dichloromethane, ethyl acetate, n-butanol, and water.

RESULTS

In the DNA topoisomerase 1 assay, n-hexane and dichloromethane fractions inhibited topoisomerase 1 and led to a decrease in the cell viability of KB cells. The dichloromethane fraction (0.1 mg/mL) also showed 77% inhibition of cell viability in KB cells compared with HaCaT cells. Treatment with dichloromethane fraction led to apoptotic cell death as evidenced by flow cytometric analysis and morphological changes. In addition, treatment with Gardenia extract dichloromethane fraction led to the partial increase of caspase-3, caspase-8 and caspase-9 activities and the cleavage of poly (ADP-ribose) polymerase.

CONCLUSION

Taken together, these results suggest that the dichloromethane fraction from Gardenia extract induces apoptotic cell death by DNA topoisomerase 1 inhibition in KB cells. These findings suggest the possibility that Gardenia extract could be developed as an anticancer modality.

A novel delta-lactam-based histone deacetylase inhibitor, KBH-A42, induces cell cycle arrest and apoptosis in colon cancer cells

In this study, we investigated the anti-tumor activity of KBH-A42 [N-hydroxy-3-(2-oxo-1-(3-phenylpropyl)-1,2,5,6-tetrahydropyridin-3-yl)propanamide], a novel synthetic histone deacetylase (HDAC) inhibitor. KBH-A42 inhibited a variety of HDAC isoforms in enzyme assays and suppressed growth of various cancer cell lines. Among the cell lines examined, colon cancer cells, including SW620, SW480 and HCT-15, were the cell types most sensitive to KBH-A42. KBH-A42 inhibition of cancer cell growth was comparable to or stronger than that of suberoylanilide hydroxamic acid (SAHA), a well-known HDAC inhibitor approved by the FDA to treat cutaneous T cell lymphomas. In SW620 cells, KBH-A42 increased the acetylation of histones, mediated cell cycle arrest (G1 arrest at low doses and G2 arrest at high doses), and induced apoptosis. The cell cycle arrest and apoptosis induced by KBH-A42 might be mediated through up-regulation of p21(Waf1) and activation of caspases, respectively. In addition, KBH-A42 inhibited SW620 tumor growth in a human tumor xenograft model. Taken together, our results indicate that KBH-A42 exerts an anti-tumor activity in vitro and in vivo and is a promising therapeutic candidate to treat human cancers.

Triptolide exerts anti-tumor effect on oral cancer and KB cells in vitro and in vivo

Triptolide (TPL), a diterpenoid triepoxide purified from the Chinese herb Tripterygium wilfordii Hook F, has been reported to potentiate the anti-tumor effect in various cancer cells. However, the effect of TPL on oral cancers is not yet evaluated. Herein we first demonstrate that TPL induces prominent growth inhibition and apoptosis in two oral cancer cell lines, SCC25 and OEC-M1 and in KB cells. Our results indicate that TPL induces a dose-dependent apoptosis of these cells at nanomolar concentration. Apoptosis signalings are both activated through time upon TPL treatment detected by elevated caspase-3, 8, 9 activities. In xenograft tumor mouse model, TPL injection successfully inhibits the tumor growth via apoptosis induction which was demonstrated by TUNEL assay. These results demonstrate that TPL exerts anti-tumor effect on oral cancer and KB cells and suggest further the potential of TPL combining with other chemotherapeutic agents or radiotherapy for advanced oral cancer.

1,5-diaryl-3-oxo-1,4-pentadienes: a case for antineoplastics with multiple targets

A number of organic molecules which contain the 1,5-diaryl-3-oxo-1,4-pentadienyl group, referred to hereafter as the dienone moiety, have antineoplastic properties. Emphasis is made on the attachment of this structural moiety to several molecular scaffolds, namely piperidines, N-acylpiperidines, cycloalkanes and 3,4-dihydro-1H-napthalenes. Many of these compounds are potent cytotoxins having micromolar and nanomolar IC(50) values towards a wide range of neoplastic and transformed cells. On occasions, greater toxicity towards neoplasms than normal cells has been demonstrated. A number of these compounds have in vivo anticancer properties and in general excellent tolerability in rodents is demonstrated. The way in which a number of physicochemical properties such as redox potentials, torsion angles, atomic charges and logP values govern cytotoxic potencies are presented. The importance of the shapes of different compounds as determined by molecular modeling in contributing to antineoplastic properties is outlined. Arguments are presented in favour of designing antineoplastics which have multiple sites of action in contrast to those bioactive molecules which have only one molecular target. A number of compounds which possess the dienone group have different modes of action some of which are chronicled in this review, such as inducing apoptosis, affecting respiration in mitochondria, inhibiting macromolecular biosynthesis and both inhibiting and stimulating certain enzymes. Other important properties of these compounds are discussed including their anti-angiogenic, MDR-revertant and antioxidant properties. It is hoped that this eulogy of the importance of the dienone group will encourage researchers to consider incorporating this structural unit into candidate cytotoxins in the future.

Apicularen A induces cell death through Fas ligand up-regulation and microtubule disruption by tubulin down-regulation in HM7 human colon cancer cells

PURPOSE

Apicularen A has been shown to cause growth inhibition and apoptosis in several cancer cell lines. However, the mechanisms of apicularen A-induced cell death and in vivo effects remain unclear. In this study, we investigated the molecular mechanisms of apicularen A-induced cell death in HM7 human colon cancer cells in vitro and anticancer activity in vivo.

EXPERIMENTAL DESIGN

We tested cytotoxicity with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, apoptosis with DNA fragmentation assay, mitochondrial membrane potential, and cell cycle with fluorescence-activated cell sorting. Caspase activation was done by fluorometry. Alterations of microtubule structure, tubulin protein, and mRNA level were assessed by immunofluorescence, Western blot, and reverse transcription-PCR. In vivo studies were assessed using nude mice tumor cell growth in xenograft model and liver colonization assay.

RESULTS

Apicularen A treatment of HM7 cells inhibited cell growth and this inhibition was partially rescued by z-VAD-fmk. Apicularen A caused accumulation of sub-G(1)-G(0), DNA fragmentation, Fas ligand induction, and activation of caspase-8 and caspase-3, but mitochondrial membrane potential was not changed. Furthermore, beta-tubulin protein and mRNA were decreased by apicularen A, but in vitro polymerization of tubulin was not affected. Concurrently, apicularen A-treated cell showed disruption of microtubule architecture. In in vivo studies, apicularen A reduced tumor volume by approximately 72% at the end of a 15-day treatment. Moreover, apicularen A reduced liver colonization as much as 95.6% (50 microg/kg/d).

CONCLUSION

Apicularen A induces cell death of HM7 cells through up-regulating Fas ligand and disruption of microtubule architecture with down-regulation of tubulin level. These findings indicate that apicularen A is a promising new microtubule-targeting compound.

Aloe-emodin induces in vitro G2/M arrest and alkaline phosphatase activation in human oral cancer KB cells

Aloe-emodin is a natural anthraquinone compound from the root and rhizome of Rheum palmatum. In this study, KB cells were treated with 2.5, 5, 10, 20, and 40 microM aloe-emodin for 1 to 5 days. The results showed that aloe-emodin inhibited cancer cells in a dose-dependent manner. Treatment with aloe-emodin at 10 to 40 microM resulted in cell cycle arrest at G2/M phase. The alkaline phosphatase (ALP) activity in KB cells increased upon treatment with aloe-emodin when compared to controls. This is one of the first studies to focus on the expression of ALP in human oral carcinomas cells treated with aloe-emodin. These results indicate that aloe-emodin has anti-cancer effect on oral cancer, which may lead to its use in chemotherapy and chemopreventment of oral cancer.

D-501036, a novel selenophene-based triheterocycle derivative, exhibits potent in vitro and in vivo antitumoral activity which involves DNA damage and ataxia telangiectasia-mutated nuclear protein kinase activation

D-501036 [2,5-bis(5-hydroxymethyl-2-selenienyl)-3-hydroxymethyl-N-methylpyrrole] is herein identified as a novel antineoplastic agent with a broad spectrum of antitumoral activity against several human cancer cells and an IC(50) value in the nanomolar range. The IC(50) values for D-501036 in the renal proximal tubule, normal bronchial epithelial, and fibroblast cells were >10 mumol/L. D-501036 exhibited no cross-resistance with vincristine- and paclitaxel-resistant cell lines, whereas a low level of resistance toward the etoposide-resistant KB variant was observed. Cell cycle analysis established that D-501036 treatment resulted in a dose-dependent accumulation in S phase with concomitant loss of both the G(0)-G(1) and G(2)-M phase in both Hep 3B and A-498 cells. Pulsed-field gel electrophoresis showed D-501036-induced, concentration-dependent DNA breaks in both Hep 3B and A-498 cells. These breaks did not involve interference with either topoisomerase-I and topoisomerase-II function or DNA binding. Rapid reactive oxygen species production and formation of Se-DNA adducts were evident following exposure of cells to D-501036, indicating that D-501036-mediated DNA breaks were attributable to the induction of reactive oxygen species and DNA adduct formation. Moreover, D-501036-induced DNA damage activated ataxia telangiectasia-mutated nuclear protein kinase, leading to hyperphosphorylation of Chk1, Chk2, and p53, decreased expression of CDC25A, and up-regulation of p21(WAF1) in both p53-proficient and p53-deficient cells. Collectively, the results indicate that D-501036-induced cell death was associated with DNA damage-mediated induction of ataxia telangiectasia-mutated activation, and p53-dependent and -independent apoptosis pathways. Notably, D-501036 shows potent activity against the growth of xenograft tumors of human renal carcinoma A-498 cells. Thus, D-501036 is a promising anticancer compound that has strong potential for the management of human cancers.

Bis(2-hydroxybenzylidene)acetone, a potent inducer of the phase 2 response, causes apoptosis in mouse leukemia cells through a p53-independent, caspase-mediated pathway

Bis(2-hydroxybenzylidene)acetone is a potent inducer of the phase 2 response through the Keap1-Nrf2-ARE pathway. This double Michael reaction acceptor reacts directly with Keap1, the sensor protein for inducers, leading to enhanced transcription of phase 2 genes and protection against oxidant and electrophile toxicities. In our efforts to identify potent chemoprotective agents, we found that in rapidly growing murine leukemia cells (L1210) low concentrations (in the submicromolar range) of bis(2-hydroxybenzylidene)acetone markedly increased the activities of NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1) and glutathione reductase, and the levels of total glutathione, three markers of the phase 2 response. In contrast, at high concentrations (in the micromolar range) the same compound caused G2/M cell cycle arrest and apoptosis. Importantly, a mutant L1210 cell line (Y8), selected for resistance to deoxyadenosine and lacking expression of p53 protein, was considerably more sensitive to the apoptotic effects of bis(2-hydroxybenzylidene)acetone. When caspase activities were evaluated in cell-free extracts prepared from treated wild type or mutant L1210 cells, the activities of caspase-3, the terminal caspase in the cascade leading to apoptosis, and caspase-10 were found to be markedly elevated. The activities of other caspases measured, caspase-1, -6 and -8, were not appreciably affected. Thus, both induction of the phase 2 response and p53-independent, caspase-3-mediated apoptosis could act cooperatively in chemoprotection. The concentration-dependent differential effects on these two pathways should be carefully considered in mechanistic explanations and strategic designs.

Adenovirus-mediated FasL gene transfer into human gastric carcinoma

AIM: To evaluate the possible value of FasL in gastric cancer gene therapy by investigating the effects of FasL expression on human gastric cancer cell line.

METHODS: An adenoviral vector encoding the full-length human FasL cDNA was constructed and used to infect a human gastric cancer (SGC-7901) cell line. FasL expression was confirmed by X-gal staining, flow cytometric analysis and RT-PCR. The effect of FasL on cell proliferation was determined by clonogenic assay, cytotoxicity was detected by MTT assay, and cell viability was measured by trypan blue exclusion. The therapeutic efficiency of Ad-FasL in vivo was investigated with a xenograft tumor model in nude mice.

RESULTS: SGC-7901 cells infected with Ad-FasL showed increased expression of FasL, resulting in significantly decreased cell growth and colony-forming activity when compared with control adenovirus-infected cells. The cytotoxicity of anti-Fas antibody (CH-11) in gastric cancer cells was stronger than that of ActD (91±8 vs 60±5, P<0.01), and the cytotoxicity of Ad-FasL was stronger than that of CH-11 (60±5 vs 50±2, P<0.05). In addition, G₁-phase arrest (67.75±0.39 vs 58.03±2.16, P<0.05) and apoptosis were observed in Ad-FasL-infected SGC-7901 cells, and the growth of SGC-7901 xenografts in nude mice was retarded after intra-tumoral injection with Ad-FasL (54% vs 0%, P<0.0001).

CONCLUSION: Infection of human gastric carcinoma cells with Ad-FasL induces apoptosis, indicating that this target gene might be of potential value in gene therapy for gastric cancer.