(4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone inhibits tubulin polymerization,induces G2/M arrest,and triggers apoptosis in human leukemia HL-60 cells

(4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone (PHT) is a known cytotoxic compound belonging to the phenstatin family. However, the exact mechanism of action of PHT-induced cell death remains to be determined. The aim of this study was to investigate the mechanisms underlying PHT-induced cytotoxicity. We found that PHT displayed potent cytotoxicity in different tumor cell lines, showing IC₅₀ values in the nanomolar range. Cell cycle arrest in G₂/M phase along with the augmented metaphase cells was found. Cells treated with PHT also showed typical hallmarks of apoptosis such as cell shrinkage, chromatin condensation, phosphatidylserine exposure, increase of the caspase 3/7 and 8 activation, loss of mitochondrial membrane potential, and internucleosomal DNA fragmentation without affecting membrane integrity. Studies conducted with isolated tubulin and docking models confirmed that PHT binds to the colchicine site and interferes in the polymerization of microtubules. These results demonstrated that PHT inhibits tubulin polymerization, arrests cancer cells in G₂/M phase of the cell cycle, and induces their apoptosis, exhibiting promising anticancer therapeutic potential.     

Genotoxic and cytotoxic effects of iron sulfate in cultured human lymphocytes treated in different phases of cell cycle.

Iron (Fe) is a common chemical element that is essential for organisms as a co-factor in oxygen transport, but that in high amounts presents a significant risk of neurodegenerative disorders. The objective of this study was to evaluate the mutagenic potential of iron sulfate. The comet assay and chromosome aberration (CA) analysis were applied to determine the DNA-damaging and clastogenic effects of iron sulfate. Human lymphocytes were treated in the quiescent phase for the comet assay and proliferative phase during the G1, G1/S, S (pulses of 1 and 6 h), and G2 phases of the cell cycle for CA analysis, with 1.25, 2.5 and 5 microg/mL concentrations of FeSO(4).7H2O. All tested concentrations were cytotoxic and reduced significantly the mitotic index (MI) in all phases of the cell cycle. They also induced CA in G1, G1/S and S (pulses of 1 and 6 h) phases. Iron sulfate also induced polyploidy in cells treated during G1. In the comet assay, this metal did not induce significant DNA damage. Our results show that Fe causes alteration and inhibition of DNA synthesis only in proliferative cells, which explain the concomitant occurrence of mutagenicity and cytotoxicity, respectively, in the lymphocytes studied.     

Genotoxic effects of aluminum chloride in cultured human lymphocytes treated in different phases of cell cycle.

Aluminum (Al) is the most abundant metal and the third common chemical element on earth. It is known that Al is toxic, especially its trivalent form (Al(3+)), that represents the its most soluble form. Al intoxication is related to some pathogenic disorders, principally neurodegeneratives ones as Parkinson and Alzheimer diseases. The present study aimed to evaluate the mutagenic potential of aluminum chloride (AlCl(3)). Comet assay and chromosome aberrations analysis were applied to evaluate the DNA-damaging and clastogenic effects of AlCl(3), respectively, in different phases of the cell cycle. Cultured human lymphocytes were treated with 5, 10, 15 and 25 microM aluminum chloride during the G1, G1/S, S (pulses of 1 and 6h), and G2 phases of the cell cycle. All tested concentrations were cytotoxic and reduced significantly the mitotic index in all phases of cell cycle. They also induced DNA damage and were clastogenic in all phases of cell cycle, specially in S phase. AlCl(3) also induced endoreduplication and polyploidy in treatments performed during G1 phase. The presence of genotoxicity and polyploidy on interphase and mitosis, respectively, suggests that aluminum chloride is clastogenic and indirectly affects the construction of mitotic fuse in all tested concentrations.     

Micronuclei,nucleoplasmic bridges,and nuclear buds induced in human lymphocytes by the fungicide signum and its active ingredients (boscalid and pyraclostrobin)

The aim of this study was to investigate the genotoxic and cytotoxic potential of the Signum fungicide and its active ingredients (boscalid and pyraclostrobin) on human peripheral blood lymphocytes using the cytokinesis‐block micronucleus (CBMN) assay. Micronuclei (MNi), nucleoplasmic bridges (NPBs), nuclear bud (NBUDs) formations, and the cytokinesis‐block proliferation index (CBPI) were evaluated in treated lymphocytes in Go (cells were treated and then kept in culture without stimulation for 24 h) and proliferation phases (cells were treated after 44 h culture in medium containing phytohemagglutinin). MN formation in lymphocytes treated in G₀ statistically increased at doses of 2, 6, and 25 μg/mL signum; 0.5 and 2 μg/mL boscalid; and 0.5, 1.5, and 2 μg/mL pyraclostrobin; while NPB formation increased at a dose of 0.25 μg/mL pyraclostrobin. All concentrations of each fungicide did not statistically increase NBUD formation, while the cytotoxicity increased the dependent on concentration in lymphocytes treated in G₀. Doses of 0.5, 1, 1.5, and 3 μg/mL signum; 0.5, 1, and 1.5 μg/mL boscalid; and 0.75 μg/mL pyraclostrobin statistically increased the MN formation in proliferating lymphocytes. NPB formation increased in proliferating lymphocytes at doses of 1, 1.5, 2, and 3 μg/mL signum and at a dose of 0.75 μg/mL pyraclostrobin. In addition, a dose of 0.75 μg/mL pyraclostrobin increased NBUD frequencies. Cytotoxicity increased with increasing concentrations of each fungicide. It is concluded that signum, boscalid, and pyraclostrobin may be genotoxic and cytotoxic in vitro human peripheral blood lymphocytes in consideration of each of the two protocols. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 723–732, 2014.     

Carnosic acid exhibits antiproliferative and proapoptotic effects in tumoral NCI-H460 and nontumoral IMR-90 lung cells

ABSTRACT

Carnosic acid (CA) is a phenolic diterpene with many important biological activities including antimicrobial, antioxidant, anti-inflammatory properties, and anti-proliferative properties. The aim of the present study was to investigate cytotoxic activity, cell cycle, apoptotic, and molecular effects attributed to CA in non-tumoral IMR-90 (human fetal lung fibroblasts), as well as tumoral NCI-H460 (human non–small-cell lung cancer) cell lines. Cell proliferation was evaluated by Real-Time Cell Analysis system, while apoptosis and cell cycle were assessed using flow cytometry. RT-qPCR was used to estimate the relative expression of genes involved in cell cycle regulation, DNA damage and repair, and apoptosis induction. CA inhibited proliferation of IMR-90 and NCI-H460 cells via cell cycle arrest at G₀/G₁ and G₂/M phases, according to the treatment concentration. The mRNA levels of genes encoding cyclins A2, B1, and B2 were downregulated in response to CA treatment of IMR-90 cells. Apoptosis was induced and proapoptotic gene PUMA was upregulated in both cell lines. mRNA levels of genes ATR, CCND1, CHK1, CHK2, MYC, GADD45A, H2AFX, MTOR, TP53, and BCL2, CASP3 were not markedly changed following CA treatments. Although CA exerted antiproliferative activity against NCI-H460 tumor cells, this phytochemical induced toxic effects in non-tumoral cells, and thus needs to be considered carefully prior to pharmacological use therapeutically.     

Cytotoxic and genotoxic effects of paraquat in Hordeum vulgare and human lymphocytes in vitro

Two phylogenetically distant types of test‐systems—root tip meristems of barley (Hordeum vulgare) and human lymphocytes in vitro were used to detect genotoxicity and cytotoxicity induced by the herbicide paraquat (PQ) in the concentration range (10^?6 to 5 × 10^?4 mol/l). As an endpoint for cytotoxicity the mitotic index (MI) was evaluated. The frequency of chromosome aberrations (CA) and the frequency of micronuclei (MN) were used as endpoints for genotoxicity. A dose‐dependent increase of CA and MN was observed in both test systems, although the values for PQ‐induced MN were somewhat lower. The increase of the genotoxic effect corresponds to a decrease of mitotic activity. The structurally reconstructed barley karyotype MK14/2034 allowed the allocation of the PQ‐specific features of aberration distribution patterns and gave information about which chromosome segments in different chromosomal positions were involved in induced aberrations. Paraquat produced preferably isochromatid breaks and “aberration hot spots” in a restricted number of heterochromatin‐containing segments. The comparative analysis of susceptibility in the used test‐systems to PQ with respect to its cytotoxic and clastogenic effect showed that the human lymphocytes were more sensitive than Hordeum vulgare. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

THE EFFECT OF TRIFLUOPERAZINE ON THE GENOTOXICITY OF BLEOMYCIN IN CULTURED HUMAN LYMPHOCYTES

The effects of trifluoperazine on the toxicity and mutagenicity of bleomycin were examined in cultured human lymphocytes. Lymphocyte cultures were initiated from three adult healthy non-smoking male volunteers. Cultures were exposed to the drugs for either three or twenty hours prior to cell collection. The toxic and clastogenic effects of the different treatments were represented by the reduction in the mitotic indices and the induction of chromosomal aberrations (CA) respectively. Both TFP and BLM significantly increased CA frequencies and reduced the mitotic indices (MI) following all treatments. The reduction in the mitotic indices and the increase in CA frequencies induced by the combined administration of both BLM and TFP were highly significant (p ≤ 0.001), but they were not significantly different from the sum of those induced by the separate treatments with the two drugs. These combined treatments, however, potentiated the odds ratios compared to those of the separate drug treatments. Therefore, though the effect of TFP on the clastogenic and cytotoxic effects of BLM was additive, the observed potentiation of the odds ratios of the combined treatments compared to those of the separate treatments suggested a significant enhancement in the expected chemotherapeutic effects of BLM when administered with TFP.     

Enhancement of the activity of bleomycin by cysteamine in a micronucleus assay in G0 human lymphocytes

The aminothiol cysteamine enhances the induction of micronuclei by bleomycin in G₀ human lymphocytes. The potentiation of bleomycin (12.5, 25, 50, or 100 μg/ml) increased with cysteamine concentration from 5 to 20 mM in a 2-h treatment before culturing the cells for the cytokinesis-block assay. The maximum clastogenic activity of bleomycin in the presence of cysteamine was more than 10-fold greater than that of the same dosage of bleomycin alone. Both the thiol and amine functions of aminothiols seem to contribute to the potentiation of bleomycin.     

Evaluation of the genotoxicity and cytotoxicity of fexofenadine in cultured human peripheral blood lymphocytes

Fexofenadine (FXF) is a new non-sedating antihistamine used in the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria. Studies on FXF genotoxicity and cytotoxicity in cultured human peripheral blood lymphocytes have not been reported so far. Therefore, the present study is the first report investigating the genotoxic and cytotoxic effects of FXF in cultured human peripheral blood lymphocytes in vitro. Cultures were treated with FXF at three concentrations (50, 100 and 150 μg/ml) for 24 and 48 h. Endpoints analyzed included: mitotic index (MI), nuclear division index (NDI), chromosomal aberrations (CA) and micronucleus (MN) assay. Mitomycin C (MMC) was used as a positive control. The results of CA and MN assays showed that FXF was not genotoxic at all the concentrations tested, meanwhile MI and NDI results showed dose-dependent decrease and significant differences were found for at least one concentration. In conclusion, the results of this study suggest that FXF has a cytotoxic effect but not genotoxic effect on human peripheral blood lymphocyte cultures. Further cytogenetic studies, especially about the cell cycle kinetics of FXF are required to elucidate the decreases in dividing cells, and biomonitoring studies should also be conducted with patients receiving therapy with this drug.     

Heterocyclic Organobismuth(III) Compound Targets Tubulin to Induce G2/M Arrest in HeLa Cells

Our previous study showed that organobismuth compounds induce apoptosis in human promyelocytic leukemia cells, although solid tumor cell lines were relatively resistant. Herein, we investigated the primary cellular target of these compounds in HeLa cells. One organobismuth compound, bi-chlorodibenzo[c,f][1,5]thiabismocine (compound 3), arrested the cell cycle at G₂/M as assessed by flow cytometry and by upregulating the expression of cyclin B1. At a low concentration (0.5 μM), compound 3 caused cell cycle arrest at the mitotic phase and induced apoptosis. At a higher concentration (>1.0 μM), it induced an arrest in the G₂/M phase, leading to apoptosis. In many cells blocked at the M phase, the organization of microtubules was affected, indicating depolymerization of the microtubule network. Western blotting demonstrated that compound 3 depolymerized microtubules similar to colchicine and nocodazole. Experiments in vitro also showed that compound 3 inhibited the assembly of purified tubulin in a concentration-dependent manner by interacting with the colchicine-binding site of tubulin through its SH groups. Heterocyclic organobismuth compounds are novel tubulin ligands.     

The effect of trifluoperazine on the genotoxicity of bleomycin in cultured human lymphocytes

The effects of trifluoperazine on the toxicity and mutagenicity of bleomycin were examined in cultured human lymphocytes. Lymphocyte cultures were initiated from three adult healthy non-smoking male volunteers. Cultures were exposed to the drugs for either three or twenty hours prior to cell collection. The toxic and clastogenic effects of the different treatments were represented by the reduction in the mitotic indices and the induction of chromosomal aberrations (CA) respectively. Both TFP and BLM significantly increased CA frequencies and reduced the mitotic indices (MI) following all treatments. The reduction in the mitotic indices and the increase in CA frequencies induced by the combined administration of both BLM and TFP were highly significant (p < or = 0.001), but they were not significantly different from the sum of those induced by the separate treatments with the two drugs. These combined treatments, however, potentiated the odds ratios compared to those of the separate drug treatments. Therefore, though the effect of TFP on the clastogenic and cytotoxic effects of BLM was additive, the observed potentiation of the odds ratios of the combined treatments compared to those of the separate treatments suggested a significant enhancement in the expected chemotherapeutic effects of BLM when administered with TFP.     

Impairment of cell cycle progression by sterigmatocystin in human pulmonary cells in vitro

Sterigmatocystin (ST) is a carcinogenic mycotoxin that is commonly found in human food, animal feed and in the indoor environment. Although the correlation between ST exposure and lung cancer has been widely reported in many studies, the cytotoxicity of ST on human pulmonary cells is not yet fully understood. In the current study, we found that ST could induce DNA double-strand breaks in a human immortalized bronchial epithelial cell line (BEAS-2B cells) and a human lung cancer cell line (A549 cells). In addition, the effects of ST on cell cycle arrest were complex and dependent on the tested ST concentration and cell type. Low concentrations of ST arrested cells in the G₂/M phase in BEAS-2B cells and in the S phase in A549 cells, while at high concentration both cells lines were arrested in S and G₂/M phases. Furthermore, we observed that the modulation of cyclins and CDK expression showed concomitant changes with cell cycle arrest upon ST exposure in BEAS-2B and A549 cells. In conclusion, ST induced DNA damage and affected key proteins involved in cell cycle regulation to trigger genomic instability, which may be a potential mechanism underlying the developmental basis of lung carcinogenesis.     

Chromosomal aberrations in cultured human lymphocytes treated with the fungicide,Thiram

In vitro effects of different concentrations of Thiram were tested on human lymphocytes to determine, by means of the chromosome aberrations (CAs) assay, whether this fungicide could induce clastogenic damage. Evidences of the effect of Thiram on human lymphocytes were limited to sister chromatid exchange, micronuclei formation, and comet assays. We evaluated 0.01, 0.1, 1.2, and 12.0 μg/mL of Thiram, where 0.01 μg/mL represent the acceptable daily intake dose set by the World Health Organization and the Food and Agriculture Organization for fruit and vegetables, whereas 0.1, 1.2, and 12.0 μg/mL are its multiple values. Results indicated that human lymphocytes treated in vitro with Thiram at concentrations of 1.20 and 12.0 μg/mL significantly increased CAs frequency, compared with the negative control, whereas at lower concentrations (0.01 and 0.1 μg/mL), this effect was not observed. However, Thiram showed a clastogenic effect also at the concentration value of 1.2 μg/mL that represents a lower value with respect to the residue limits found in Italy for grapes, strawberries, potatoes, tobacco, and other fruits and vegetables. Finally, according to some evidence obtained from the study of other fungicides, Thiram produced a significant reduction in the mitotic index with increasing concentration.     

Molecular Cytotoxic Mechanisms of 1-(3,4,5-Trihydroxyphenyl)-dodecylbenzoate in Human Leukemia Cell Lines

Recent studies have shown that gallic acid and its alkylesters induce apoptosis in different cell lines. Since new compounds with biological activity and less cytotoxicity to normal cells are necessary for cancer therapy, the aim of this study was to evaluate the cytotoxic effect of 1-(3,4,5-trihydroxyphenyl)-dodecylbenzoate on human acute myeloid leukemia K562 cells and on human acute lymphoblastic leukemia Jurkat cells. The cell viability was determined by MTT method. The apoptosis induction was assessed by bromide and acridine orange staining and by Annexin V-FITC Apoptosis Detection kit. The cell cycle analysis was carried out by flow cytometry using propidium iodide. Cytometric analysis was also performed to evaluate the expression of the following proteins: AIF, p53, Bcl-2 and Bax. The mitochondrial potential was also assessed by flow cytometry using MitoView633 kit. The results showed that the compound significantly reduced the cell viability of K562 and Jurkat cells in a concentration and time dependent manner (IC₅₀ of 30 μM). The compound induced cell cycle arrest in G₀/G₁phase and significantly increased the proportion of cells in the sub-G₀/G₁phase. Apoptosis was confirmed by the sight of morphological characteristics of apoptosis and by phosphatidylserine externalization (73.47±5.71% of cells expressing annexin). The results also showed that the compound promotes a modification in Bax:Bcl-2 ratio and increases p53 expression. Thus, it is possible to conclude that 1-(3,4,5-trihydroxyphenyl)-dodecylbenzoate induces apoptosis by inhibiting the antiapoptotic protein Bcl-2 and by increasing the release of AIF, Bax and p53. In addition, it blocks the cell cycle at G₀/G₁, stopping cell proliferation. So far, the results suggest that this compound may have a potential therapeutic effect against leukemia cells.     

A novel sulfonamide agent,MPSP-001, exhibits potent activity against human cancer cells in vitro through disruption of microtubule

Aim:

To evaluate the anti-cancer effects of a new sulfonamide derivative, 2-(N-(3-chlorophenyl)-4-methoxyphenylsulfonamido)-N-hydroxypropanamide (MPSP-001).

Methods:

Human cancer cell lines (HepG2, THP-1, K562, HGC-27, SKOV3, PANC-1, SW480, Kba, HeLa, A549, MDA-MB-453, and MCF-7) were examined. The cytotoxicity of MPSP-001 was evaluated using the WST-8 assay. Cell cycle distribution was examined with flow cytometry. Mitotic spindle formation was detected using immunofluorescence microscopy. Apoptosis-related proteins were examined with Western blot using specific phosphorylated protein antibodies. Competitive tubulin-binding assay was performed to test whether the compound competitively bound to the colchicine site. Molecular docking was performed to explore the possible binding conformation.

Results:

MPSP-001 potently inhibited the growth of the 12 different types of human cancer cells with the IC₅₀ values ranging from 1.9 to 15.7 μmol/L. The compound exerted potent inhibition on the drug-resistant Kb/VCR and MCF-7/ADR cells, as on Kba and MCF-7 cells. In HeLa, HGC-27, A549, and other cells, the compound (5 μmol/L) caused cell cycle arrest at the G₂/M phase, and subsequently induced cell apoptosis. In Hela cells, it prevented the mitotic spindle formation. Furthermore, the compound dose-dependently inhibited polymerization of tubulin in vitro, and directly bound to the colchicine-site of β-tubulin. Molecular docking predicted that the compound may form two hydrogen bonds to the binding pocket. The compound showed synergistic effects with colchicine and taxol in blocking mitosis of HeLa cells.

Conclusion:

MPSP-001 shows a broad-spectrum of anti-tumor efficacy in vitro and represents a novel structure with anti-microtubule activity.     

Antigenotoxic effect of hyperoside against Mitomycin C and hydrogen peroxide-induced genotoxic damage on human lymphocytes

Hyperoside is a flavonol glycoside isolated from various plant genera such as Hypericum and Crataegus. It has an important place in the human diet and is used medically to relieve pain and ameliorate cardiovascular functions. However, a comprehensive profile of the genotoxic and antigenotoxic effects of hyperoside is not known. The current study aimed to investigate the genotoxic and antigenotoxic effects of hyperoside against genetic damages induced by two genotoxins (MMC and H₂O₂) using chromosomal aberrations (CAs), sister chromatid exchanges (SCEs), and micronucleus (MN) assays in human peripheral blood lymphocytes in vitro. Blood lymphocytes were incubated with 7.8–62.5 μg/mL concentrations of hyperoside alone and simultaneously with 0.20 μg/mL Mitomycin C (MMC) or 100 μM Hydrogen peroxide (H₂O₂). Hyperoside did not exhibit genotoxic potential in the CA, SCE, and MN assays. Moreover, it did not cause a decrease in mitotic index (MI) which is an indicator of cytotoxicity. On the other hand, hyperoside significantly decreased CA, SCE, and MN (except for MMC treatment) frequencies induced by MMC and H₂O₂. Hyperoside, increased mitotic index against both mutagenic agents at 24-h treatment when compared to positive control. Our results demonstrate that hyperoside exhibited antigenotoxic effects rather than genotoxic in vitro human lymphocytes. Therefore, hyperoside may be a potential preventive agent in inhibiting chromosomal and oxidative damage induced by genotoxic chemicals.     

Cross-talk between phosphatidic acid and ceramide during ethanol-induced apoptosis in astrocytes

Background

Anticancer bisdioxopiperazines, including ICRF-154, razoxane (Raz, ICRF-159) and ICRF-193, are a family of anticancer agents developed in the UK, especially targeting metastases of neoplasms. Two other bisdioxopiperazine derivatives, probimane (Pro) and MST-16, were synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. Cytotoxic activities and mechanisms of Raz (+)-steroisomer (ICRF-187, dexrazoxane), Pro and MST-16 against tumor cells were evaluated by MTT colorimetry, flow cytometry and karyotyping.

Results

Pro was cytotoxic to human tumor cell lines in vitro (IC₅₀<50 μM for 48 h). Four human tumor cell lines (SCG-7901, K562, A549 and HL60) were susceptible to Pro at low inhibitory concentrations (IC₅₀ values < 10 μM for 48 h). Although the IC₅₀ against HeLa cell line of vincristine (VCR, 4.56 μM), doxorubicin (Dox, 1.12 μM) and 5-fluoruouracil (5-Fu, 0.232 μM) are lower than Pro (5.12 μM), ICRF-187 (129 μM) and MST-16 (26.4 μM), VCR, Dox and 5-Fu shows a low dose-related – high cytotoxic activity. Time-response studies showed that the cytotoxic effects of Pro are increased for 3 days in human tumor cells, whereas VCR, Dox and 5-Fu showed decreased cytotoxic action after 24 h. Cell cycle G₂/M phase arrest and chromosome segregation blocking by Pro and MST-16 were noted. Although there was similar effects of Pro and MST-16 on chromosome segregation blocking action and cell cycle G₂/M phase arrest at 1- 4 μM, cytotoxicity of Pro against tumor cells was higher than that of MST-16 in vitro by a factor of 3- 10 folds. Our data show that Pro may be more effective against lung cancer and leukemia while ICRF-187 and MST-16 shows similar IC₅₀ values only against leukemia.

Conclusion

It suggests that Pro has a wider spectrum of cytotoxic effects against human tumor cells than other bisdioxopiperazines, especially against solid tumors, and with a single cytotoxic pathway of Pro and MST-16 affecting chromosome segregation and leading also to cell G₂/ M phase arrests, which finally reduces cell division rates. Pro may be more potent than MST-16 in cytotoxicity. High dose- and time- responses of Pro, when compared with VCR, 5-Fu and Dox, were seen that suggest a selectivity of Pro against tumor growth. Compounds of bisdioxopiperazines family may keep up their cytotoxic effects longer than many other anticancer drugs.     

Antitumor efficacy and apoptotic activity of substituted chloroalkyl 1H-benz[de]isoquinoline-1,3-diones: a new class of potential antineoplastic agents

A series of ten chloroalkyl 1H-benz[de]isoquinoline-1,3-diones (naphthalimides) were synthesized and evaluated for antitumor activity. Amongst them, new compounds 2d and 2i carrying a 6-NO₂ substituent in the aromatic portion of the molecule possessed significant antineoplastic activity. The most active compound 2i had elicited significant cytotoxicity in 15 human tumor cell lines namely Leukemia: MOLT-4, HL-60; Lymphoma: U-937; Colon: 502713, HT-29, SW-620, HCT-15, COLO-205; Liver: Hep-2; Prostate DU-145, PC-3; Breast: MCF-7; Neuroblastoma: IMR-32, SK-N-SH and Ovary: OVCAR-5 out of the 17 cell lines screened. Flow cytometric analysis performed to study the effect of compound 2i on the progression of cell cycle of MOLT-4 cells, revealed rise in sub-G₁ fraction and concomitant accumulation of cells in S and G₂/M phases, indicating apoptosis, mitotic arrest and/or delay in exit of daughter cells from mitotic cycle respectively. It also induced caspase-mediated apoptosis of MOLT-4 cells in a dose dependant manner. Light and electron microscopic studies revealed characteristic morphology of apoptotic MOLT-4 cells after in vitro treatment with 10 μM concentration of the compound. Apoptosis induction was also observed in HL-60 cells by compounds 2d and 2i to an extent much greater than camptothecin and cis-platin at 10 μM concentration. Both the compounds have shown minimal suppressive effect on human PBMC having high IC₅₀ values of 3,582 and 1,536 μM respectively. These compounds inhibited DNA and RNA synthesis in murine ascites Sarcoma-180 tumor cells in vitro at 8 μM concentration. Above results indicate promising chemotherapeutic potential of the key compound 2i.     

Cell cycle-dependent inhibition of the proliferation of human neural tumor cell lines by iron chelators

The current studies were designed to examine the conditions under which the ferric iron chelator desferrioxamine (DFO) arrested cell cycle progression and hence the proliferation of neural cell lines in vitro. DFO arrested proliferation at different stages of the cell cycle depending on the concentration and duration of drug exposure. Twenty-four-hour treatment with 160 μM DFO arrested glioma cells in G₁, whereas 72-hr treatment with 10 μM DFO acted to slow the passage of glioma cells through the cell cycle, eventually accumulating in G₂/M. Another iron chelator, ADR 529, also inhibited the proliferation of glioma cells by lengthening the period of the cycle and causing the cells to arrest in G₂/M. The effects of 10 and 160 μM DFO were irreversible after 24 and 48 hr, respectively, and 10 μM DFO became cytotoxic after 3 days. These observations demonstrate that DFO has different effects on the proliferation of neural tumor cell lines depending on the concentration and time of exposure, which result in different sites of cell cycle arrest. These different in vitro actions of DFO may have ramifications for the successful application of iron chelator therapy in vivo.     

Design,synthesis, and biological evaluation of novel 4‐phenoxypyridine derivatives as potential antitumor agents

A series of novel 4‐phenoxypyridine derivatives containing the 4‐oxo‐1,4‐dihydropyridazine‐3‐carboxamide moiety were synthesized and evaluated for their in vitro cytotoxic activity against the A549 cancer cell line, and some compounds were further examined for their cytotoxic activity against the H460, BGC823, MKN45, and HT‐29 cancer cell lines. Most of the compounds exhibited moderate to significant cytotoxicity. The most promising compound 15b (with VEGFR2 inhibitory concentration [IC₅₀] value of 0.23 μM) showed remarkable cytotoxicity against A549, BGC‐823, MKN45, H460, and HT‐29 cells, with IC₅₀ values of 0.75, 1.68, 2.63, 5.08 and 7.22 μM, respectively. Their preliminary structure‐activity relationship studies indicate that electron‐withdrawing groups on the terminal phenyl rings are beneficial for improving the antitumor activity. Moreover, treatment of A549 cells with compound 15b resulted in cell cycle arrest in the G₀/G₁ phase in a dose‐dependent manner. Further apoptotic studies and acridine orange/ethidium bromide staining were also performed on A549 cells, which showed that compound 15b could induce apoptosis. Wound‐healing assay results indicated that compound 15b strongly inhibited A549 cell motility.