Comparison of three cytotoxicity tests in the evaluation of the cytotoxicity of a spermine analogue on human breast cancer cell lines

Gamma radiation coupled ADP-ribosyl transferase activity of Pseudomonas aeruginosa PE24 moiety

The ADP-ribosyl transferase activity of P. aeruginosa PE24 moiety expressed by E. coli BL21 (DE3) was assessed on nitrobenzylidene aminoguanidine (NBAG) and in vitro cultured cancer cell lines. Gene encoding PE24 was isolated from P. aeruginosa isolates, cloned into pET22b( +) plasmid, and expressed in E. coli BL21 (DE3) under IPTG induction. Genetic recombination was confirmed by colony PCR, the appearance of insert post digestion of engineered construct, and protein electrophoresis using sodium dodecyl-sulfate polyacrylamide gel (SDS-PAGE). The chemical compound NBAG has been used to confirm PE24 extract ADP-ribosyl transferase action through UV spectroscopy, FTIR, c¹³-NMR, and HPLC before and after low-dose gamma irradiation (5, 10, 15, 24 Gy). The cytotoxicity of PE24 extract alone and in combination with paclitaxel and low-dose gamma radiation (both 5 Gy and one shot 24 Gy) was assessed on adherent cell lines HEPG2, MCF-7, A375, OEC, and Kasumi-1 cell suspension. Expressed PE24 moiety ADP-ribosylated NBAG as revealed by structural changes depicted by FTIR and NMR, and the surge of new peaks at different retention times from NBAG in HPLC chromatograms. Irradiating recombinant PE24 moiety was associated with a reduction in ADP-ribosylating activity. The PE24 extract IC50 values were < 10 μg/ml with an acceptable R² value on cancer cell lines and acceptable cell viability at 10 μg/ml on normal OEC. Overall, the synergistic effects were observed upon combining PE24 extract with low-dose paclitaxel demonstrated by the reduction in IC50 whereas antagonistic effects and a rise in IC50 values were recorded after irradiation by low-dose gamma rays. KEY POINTS: • Recombinant PE24 moiety was successfully expressed and biochemically analyzed. • Low-dose gamma radiation and metal ions decreased the recombinant PE24 cytotoxic activity. • Synergism was observed upon combining recombinant PE24 with low-dose paclitaxel.

Estimating the two graph dextran-stearic acid-spermine polymers based on iron oxide nanoparticles as carrier for gene delivery

Non-viral gene carriers have shown noticeable potential in gene delivery because of limited side effects, biocompatibility, simplicity, and the ability to take advantage of electrostatic interactions. However, the low transfection rate of non-viral vectors under physiological conditions is controversial. This study aimed to decrease the transfection time using a static magnetic field. We used self-assembled cationic polysaccharides based on dextran-stearic acid-spermine (DSASP) conjugates associated with Fe₃ O₄ superparamagnetic nanoparticles to investigate their potential as gene carriers to promote the target delivery. Our findings illustrate that the magnetic nanoparticles are spherical with a positive surface charge and exhibit superparamagnetic behavior. The DSASP-pDNA/Fe₃ O₄ complexes offered a strong pDNA condensation, protection against DNase degradation, and significant cell viability in HEK 293T cells. Our results demonstrated that although conjugation of stearic acid could play a role in transfection efficiency, DSASP magnetic carriers with more spermine derivatives showed better affinity between the amphiphilic polymer and the negatively charged cell membrane.

Comparative cytotoxic study of silica materials functionalised with essential oil components in HepG2 cells

This work evaluated the cytotoxic effect of different EOCs-functionalised silica particle types. The in vitro toxicity of eugenol and vanillin-immobilised SAS, MCM-41 microparticles and MCM-41 nanoparticles was evaluated on HepG2 cells, and compared to free EOCs and pristine materials. The results revealed that free essential oil components and bare silica had a mild cytotoxic effect on HepG2 cells. However, the comparative study showed that free eugenol and vanillin had a milder cytotoxic effect than the equivalent concentrations of immobilised components on the different silica particles, while differences in cell viability between the bare and functionalised particles relied on the type of analysed material. The most cytotoxic materials were eugenol and vanillin-functionalised MCM-41 micro with IC₅₀ values of 0.19 and 0.17 mg/mL, respectively, at 48 h exposure. Differences in cytotoxicity between functionalised particles may be attributed to the density of the functional components on their surface as a result of the functionalisation reaction performance for different materials. The study of the physico-chemical properties of particles demonstrated that cationic nature and increased hydrophobicity could be responsible for promoting cell-particle interactions for the eugenol and vanillin functionalised silica particles, enhancing their cytotoxic behaviour.

DRAQ7 as an Alternative to MTT Assay for Measuring Viability of Glioma Cells Treated With Polyphenols

BACKGROUND/AIM

The tetrazolium-based MTT cytotoxicity assay is well established for screening putative anti-cancer agents. However, it has limitations including lack of reproducibility with glioma cells treated with polyphenols. The aim of this study was to evaluate whether a flow cytometric assay with the anthraquinone, DRAQ7, was a better alternative than the colorimetric MTT assay for measuring cell viability.

MATERIALS AND METHODS

Two glioma cell lines (IPSB-18, U373) and 1 pancreatic cancer cell line (AsPC-1) were treated with 4 polyphenols, namely red grape seed extract, red clover extract, anthocyanin-rich extract and curcumin. Cell viability was assessed using MTT assay and DRAQ7 staining.

RESULTS

Limitations of MTT assay included lack of sensitivity and interference with the structure and absorbance spectra of polyphenols. Also, DMSO was toxic to glioma cells. Microscopic observations of cells treated with polyphenols confirmed the range of IC₅₀ values evaluated by DRAQ7, but not by the MTT assay.

CONCLUSION

DRAQ7 is a better alternative than MTT for measuring viability of glioma cells treated with brightly coloured polyphenols.

A cytosol derived factor of Group B streptococcus prevent its invasion into human epithelial cells

Group B streptococcus (GBS) or Streptococcus agalactiae, is an opportunistic pathogen causing a wide range of infections like pneumonia, sepsis, and meningitis in newborn, pregnant women and adults. While this bacterium has adapted well to asymptomatic colonization of adult humans, it still remains a potentially devastating pathogen to susceptible infants. Advances in molecular techniques and refinement of in vitro and in vivo model systems have elucidated key elements of the pathogenic process, from initial attachment to the maternal vaginal epithelium to penetration of the newborn blood-brain barrier. Still, the formidable array of GBS virulence factors makes this bacterium at the forefront of neonatal pathogens. The involvement of bacterial components in the host-pathogen interaction of GBS pathogenesis and its related diseases is not clearly understood. In this study we demonstrated the role of a 39 kDa factor from GBS which plays an important role in the process of its invasion. We found a homogeneous 39 kDa factor from the cytosol of GBS after following a combination of sequential purification steps involving molecular sieving and ion exchange chromatography using ACTA-FPLC system. Its N-terminal sequence showed a homology with xenobiotic response element type transcriptional regulator protein, a 40 kDa protein of Streptococcus. This factor leads to inhibition of GBS invasion in HeLa and A549 cells. This protein also showed sensitivity and specific cross reactivity with the antibodies raised against it in New Zealand white rabbits by western immunoblotting. This inhibitory factor was further confirmed tolerant for its cytotoxicity. These results add a novel aspect to bacterial pathogenesis where bacteria's own intracellular protein component can act as a potential therapeutic candidate by decreasing the severity of disease thus promoting its invasion inhibition.

Raman microspectroscopy for probing the impact of a dietary antioxidant on human breast cancer cells

Breast cancer is the second most common type of cancer worldwide and the most frequent among women, being the fifth cause of death from neoplastic disease. Since this is an oxidative-stress related neoplasia, it is largely preventable. A dietary isoflavone abundant in soybean - daidzein - is currently being investigated owing to its chemopreventive and/or chemotherapeutic properties towards the human MDA-MB-231 (metastatic, estrogen-unresponsive) and MCF-7 (estrogen-responsive) breast cancer cell lines. Biological assays for evaluation of antitumour and anti-invasive activities were combined with state-of-the-art vibrational microspectroscopy techniques. At 50 and 100 μM concentrations and 48 h incubation time, daidzein was found to induce a marked decrease in cell viability (ca. 50%) for MDA-MB-231 and MCF-7 cells (respectively ca. 50% and 42%) and 40% inhibition of cell migration. MicroRaman analysis of fixed cells upon exposure to this isoflavone unveiled its metabolic impact on both cell lines. Multivariate data analysis (unsupervised PCA) led to a clear discrimination between the control and DAID-exposed cells, with distinctive effects on their biochemical profile, particularly regarding DNA, lipids and protein components, in a cell-dependent way. This is the first reported study on the impact of dietary antioxidants on cancer cells by microRaman techniques.

Cytotoxic Sesquiterpene Lactones from Kauna lasiophthalma Griseb

Two new eudesmane derivatives (3 and 8) were isolated from the ethanol extract of the aerial parts of Kaunia lasiophthalma Griseb, together with 14 known eudesmane, germacrane, and guaiane sesquiterpenes, and four flavones. The structures and relative configurations of all the compounds were established by NMR spectroscopy and high-resolution mass spectrometry. The anticancer activity of sesquiterpenes 1, 3, 6–9, 11, 12, 14, and 16 was evaluated in vitro with the breast cancer cell lines HCC1937, JIMT-1, L56Br-C1, MCF-7, and SK-BR-3, and compared with the cytotoxicity in the non-cancerous breast epithelial cell line MCF-10A. All compounds were found to possess anticancer activity, and compound 1 was the most potent in all of the investigated cancer cell lines with IC₅₀ values ranging between 2.0 and 6.2 μM. In order to demonstrate the importance of the α-methylene-γ-lactone/ester moiety present in all compounds for the effects on the cells, the methyl cysteine adduct 21 was prepared from 9 and found to be inactive or considerably less potent.

Increased breast cancer cell toxicity by palladination of the polyamine analogue N (1),N (11)-bis(ethyl)norspermine

Breast cancer is one of the most common malignant tumor forms among women and many women succumb to their disease. Thus, new anticancer agents that can efficiently improve patient survival are of the utmost importance. In this study, the effects of the polyamine analogues N (1),N (11)-bis(ethyl)norspermine (BENSpm) and N (1)-cyclo-propylmethyl-N (11)-ethylnorspermine (CPENSpm) and the synthesized dinuclear complexes Pd2BENSpm (Pd-BENSpm), Pt2CPENSpm (Pt-CPENSpm) and Pd2Spm (Pd-Spm) were investigated in normal-like breast epithelial MCF-10A cells and the breast cancer cell lines JIMT-1 and L56BR-C1. The overall data show that palladination of BENSpm resulted in enhanced cytotoxicity, in contrast to platination of CPENSpm that reduced cytotoxicity, which might be explained by differences in the cellular uptake of Pd-BENSpm and Pt-CPENSpm. BENSpm and Pd-BENSpm treatment reduced the CD44(+)CD24(-) putative cancer stem cell population, evaluated by flow cytometry. Furthermore, Pd-BENSpm was the most efficient compound regarding induction of DNA damage and decrease in colony formation in soft agar. Pt-CPENSpm and Pd-Spm, on the other hand, were shown to be the least toxic compounds of all tested. Pd-Spm efficiently reduced the cellular glutathione levels, which probably was a consequence of its metabolic inactivation by conjugation to this endogenous thiol. The normal-like cells were found to be less sensitive to the agents than the breast cancer cells. Our findings show that Pd-BENSpm exhibits promising anticancer effects which render it suitable for further optimization to develop a new metal-based chemotherapeutic drug for breast cancer treatment.

Spiro-bicyclo[2.2.2]octane derivatives as paclitaxel mimetics. Synthesis and toxicity evaluation in breast cancer cell lines

Paclitaxel is one of the most important anti-cancer agents introduced during the last 20 years. However, the use of paclitaxel is limited by undesirable side effects as well as the development of drug resistance. Here, we report a synthetic strategy towards spiro-bicyclo[2.2.2]octane derivatives, which includes double Michael addition and ring-closing metathesis as key synthetic steps. This strategy was used to synthesize a series of spiro-bicyclic compounds designed to be paclitaxel mimetics, which were evaluated in human breast-derived cell lines. One of these paclitaxel mimetics showed toxicity, although at higher concentrations than paclitaxel itself. In addition, two other spiro-bicyclic compounds, lacking the paclitaxel side chain, showed toxicity.

Norspermidine and novel Pd(II) and Pt(II) polynuclear complexes of norspermidine as potential antineoplastic agents against breast cancer

Background

New strategies are needed for breast cancer treatment and one initial step is to test new chemotherapeutic drugs in breast cancer cell lines, to choose candidates for further studies towards clinical use.

Methodology and Findings

The cytotoxic effects of a biogenic polyamine analogue – norspermidine – and its trinuclear Pd(II) and Pt(II) complexes – Pd₃NSpd₂ and Pt₃NSpd₂, respectively – were investigated in one immortalized normal-like and three breast cancer cell lines. The normal-like MCF-10A cells were least sensitive to the compounds, while growth inhibition and cell death was observed in the cancer cell lines. Norspermidine and its Pd(II) complex were generally shown to have stronger antiproliferative effects than the corresponding Pt(II) complex. Moreover, both norspermidine and the Pd(II) complex reduced the cellular activity of the growth-related enzyme, ornithine decarboxylase (ODC) to a lower level than the Pt(II) complex in most of the cell lines examined. Treatment with norspermidine or the Pd(II) complex reduced the number of colonies formed in a soft agar assay performed with the breast cancer cell lines, indicating that these compounds reduced the malignancy of the breast cancer cells. The effect of norspermidine or the Pd(II) complex on colony formation was much stronger than that observed for the Pt(II) complex. The results from a new mammalian genotoxicity screen together with those of a single cell gel electrophoresis assay indicated that none of the drugs were genotoxic at a 25 µM concentration.

Main Conclusions

Overall, norspermidine and its Pd(II) complex were shown to have strong antiproliferative effects. In comparison, the effects obtained with the Pd(II) complex were much stronger than that of the Pt(II) complex. The results obtained in the present study demonstrate that the trinuclear Pd(II) complex of norspermidine (Pd₃NSpd₂) may be regarded as a potential new metal-based drug against breast cancer, coupling a significant efficiency to a low toxicity.

Novel anti-apoptotic effect of the retinoblastoma protein: implications for polyamine analogue toxicity

The retinoblastoma protein (pRb) pathway is frequently altered in breast cancer cells. pRb is involved in the regulation of cell proliferation and cell death. The breast cancer cell line L56Br-C1 does not express pRb and is extremely sensitive to treatment with the polyamine analogue N(1),N(11)-diethylnorspermine (DENSPM) which causes apoptosis. Polyamines are essential for the regulation of cell proliferation, cell differentiation and cell death. DENSPM depletes cells of polyamines, e.g., by inducing the activity of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT). In this study, L56Br-C1 cells were transfected with human pRb-cDNA. Overexpression of pRb inhibited DENSPM-induced cell death and DENSPM-induced SSAT activity. This suggests that the pRb protein level is a promising marker for polyamine depletion sensitivity and that there is a connection between pRb and the regulation of SSAT activity. We also show that SSAT protein levels and SSAT activity do not always correlate, suggesting that there is an unknown regulation of SSAT.

Analogues of peptide SMAP-29 with comparable antimicrobial potency and reduced cytotoxicity

SMAP-29 (sheep myeloid antimicrobial peptide-29) is a peptide with potent antibacterial properties. However, it is also highly cytotoxic both to human red blood cells (hRBCs) and human embryonic kidney (HEK) cells. In this study, some of the amino acids of SMAP-29 were changed in an attempt to reduce haemolytic activity whilst maintaining high antibacterial efficacy. These analogues, plus other analogues described in the literature with potent antimicrobial activity against Gram-positive bacteria coupled with no or low haemolytic activity, were evaluated for their cytotoxicity (hRBCs and HEK cells) as well as antimicrobial efficacy against two Gram-positive (Bacillus anthracis and Bacillus globigii) and two Gram-negative bacteria (Escherichia coli and Burkholderia thailandensis). The analogues previously described in the literature were found to have low antibacterial and haemolytic activity. Two of the designed analogues had comparable antibacterial efficacy with SMAP-29 against B. anthracis but reduced haemolytic activity and therefore had a therapeutic index that was enhanced 2.3-2.6-fold over that of SMAP-29.

Effect of polyamine deficiency on proteins involved in Okazaki fragment maturation

Polyamine depletion causes S phase prolongation, and earlier studies indicate that the elongation step of DNA replication is affected. This led us to investigate the effects of polyamine depletion on enzymes crucial for Okazaki fragment maturation in the two breast cancer cell lines MCF-7 and L56Br-C1. In MCF-7 cells, treatment with N(1),N(11)-diethylnorspermine (DENSPM) causes S phase prolongation. In L56Br-C1 cells the prolongation is followed by massive apoptosis. In the present study we show that L56Br-C1 cells have substantially lower basal expressions of two Okazaki fragment maturation key proteins, DNA ligase I and FEN1, than MCF-7 cells. Thus, these two proteins might be promising markers for prediction of polyamine depletion sensitivity, something that can be useful for cancer treatment with polyamine analogues. DENSPM treatment affects the cellular distribution of FEN1 in L56Br-C1 cells, but not in MCF-7 cells, implying that FEN1 is affected by or involved in DENSPM-induced apoptosis.

Subcellular distribution of spermidine/spermine N1-acetyltransferase

The subcellular distribution of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) was studied in L56Br-C1 cells treated with 10 microM N(1),N(11)-diethylnorspermine (DENSPM) for 24 h. Cells were fractioned into three subcellular fractions. A particulate fraction containing the mitochondria was denoted as the mitochondrial fraction. After DENSPM treatment, an increase in SSAT activity was mainly found in the mitochondrial fraction. Western blot analysis showed an increased level of the SSAT protein in the mitochondrial fraction compared to the cytosolic fraction. Immunofluorescence microscopy and immunogold labeling transmission electron microscopy also showed a mitochondrial association of SSAT. Transmission electron microscopy revealed that the endoplasmic reticulum was devoid of ribosomes in DENSPM-treated cells, in contrast to control cells that contained ample ribosomes. An increased SSAT activity in connection with the mitochondria may be part of the mechanism of DENSPM-induced apoptosis.

In vitro cytotoxic activities of (+)-usnic acid and (-)-usnic acid on V79, A549, and human lymphocyte cells and their non-genotoxicity on human lymphocytes

This study investigates cytotoxic and genotoxic activities of (+)-Usnic acid and (-)-usnic acid isolated from the lichen Ramalina farinacea and the lichen Cladonia foliacea, respectively. To determine the activities of these acids, we used the MTT assay on V79 (Chinese hamster lung fibroblast like) and A549 (human lung carcinoma epithelial like) cell lines and cytokinesis-blocked micronucleus (CBMN) assay in human lymphocytes in vitro. Our results suggest that both enantiomers of usnic acid are non-genotoxic shown by the absence of micronucleus induction in human lymphocytes and have significant cytotoxic and apoptotic effects to induce cell killing in cultured human lymphocytes, V79 and A549 cell lines. Even low doses of (+)-usnic acid showed high cytotoxic activity against cancerous cells. The MTT results and cell proliferation index (CPI) values based on the CBMN test results are found in good agreement.

Differences in estimates of cisplatin-induced cell kill in vitro between colorimetric and cell count/colony assays

The aim of this study was to evaluate some bioassays that are different in principle: cell counting, colony forming assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT), sulforhodamine B (SRB), crystal violet, and alamarBlue, with respect to their ability to measure cisplatin-induced cell death of in vitro-cultivated squamous cell carcinoma of the head and neck (SCCHN). Cisplatin was applied in concentrations of 1.0, 5.0, 10.0, 50.0, and 100 microM. The cells were incubated for 1 h, and the cell survival was measured 5 d after treatment. We found the colorimetric assays and cell counting to be comparable. The colony forming assay indicated a higher degree of cell kill compared with the other techniques. Measurement of cell survival after treatment with cisplatin can be done by use of any of the above tested assays. However, the majority of SCCHN cell lines available do not form colonies easily, or at all. Therefore, comparing the chemosensitivity between such cell lines is limited to alternative assays. In this respect, any of the tested colorimetric assays can be used. However, they seem to underestimate cell kill. Cell counting is also an alternative. This technique, however, is time consuming and operator dependent, as in the case of manual counting, or relatively expensive when counting is performed electronically, compared with the colorimetric assays.

Inhibition of cell proliferation and induction of apoptosis by N1,N11-diethylnorspermine-induced polyamine pool reduction

Reduction of cellular polyamine pools results in inhibition of cell proliferation and sometimes in induction of cell death. Reduction of cellular polyamine pools can be achieved by several strategies involving all the mechanisms of polyamine homoeostasis, i.e. biosynthesis, catabolism and transport across the cell membrane. In the present paper, we concentrate on results achieved using the polyamine analogue DENSPM (N1,N11-diethylnorspermine) on different cell lines. We discuss polyamine levels in DENSPM-treated cells in relation to effects on cell cycle kinetics and induction of apoptosis. To really understand the role of polyamines in cell cycle regulation and apoptosis, we believe it is now time to go through the vast polyamine literature in a meta-analysis-based manner. This short review does not claim to be such a study, but it is our hope to stimulate such studies in the polyamine field. Such work is especially important from the viewpoint of introducing drugs that affect polyamine homoeostasis in the treatment of various diseases such as cancer.

Assessing the data quality in predictive toxicology using a panel of cell lines and cytotoxicity assays

In vitro cell viability assays have a central role in predictive toxicology, both in assessing acute toxicity of chemicals and as a source of experimental data for in silico methods. However, the quality of in vitro toxicity databanks fluctuates dramatically because information they contain is obtained under varying conditions and in different laboratories. The aim of this study was to identify the factors responsible for these deviations and thus the quality of the data extracted for predictive toxicology. Three cell viability assays measuring LDH leakage, WST-1 reduction, and intracellular ATP were compared in an automated environment using four mammalian cell lines: Caco-2, Calu-3, Huh-7, and BHK. Using four standard compounds--polymyxin B, gramicidin, 5-fluorouracil, and camptothecin--a significant lack of sensitivity in LDH assay compared with the other assays was observed. Because the viability IC(50) values for the standards were similar among the cell lines, the biochemical characteristics of different cell lines seem to play only a minor role, with an exception being the hepatocellular Huh-7 cell line. Toxicity assessment of new 1,2,4-triazoles revealed significant differences in their toxic potential, and the results indicate the same sensitivity profile among the assays as observed with the standard compounds. Overall, it can be argued that the assay selection is the most important factor governing the uniform quality of the data obtained from in vitro cell viability assays.

Comparison of results of the CellTiter Blue, the tetrazolium (3-[4,5-dimethylthioazol-2-yl]-2,5-diphenyl tetrazolium bromide), and the lactate dehydrogenase assay applied in brain cells after exposure to advanced glycation endproducts

Advanced glycation endproducts (AGEs) arise in vivo from the reaction of proteins with sugars or dicarbonyl compounds. They are thought to be involved in the pathogenesis of several diseases such as atherosclerosis, diabetes mellitus, renal failure, and Alzheimer's disease (AD). Several binding molecules for AGEs have been described and it is assumed that many of the effects of AGEs are mediated by receptors like the receptor for AGEs (RAGE). AGEs are known to induce the release of inflammatory cytokines from activated glia in the AD brain and thus AGEs affect the cell viability of neurons and glia. In cell culture experiments controversial effects of AGEs on cell growth and viability were reported by different research groups ranging from stimulation to inhibition of the cell viability. In the present study, the effect of in vitro prepared highly modified AGEs on the viability and the membrane integrity of cultured brain cells was investigated. Three different brain cell lines were treated with glucose human serum albumin AGEs (Glc-AGEs) and methyl glyoxal human serum albumin AGEs (MG-AGEs). To investigate the effect of these model AGEs on cell viability the CellTiter Blue (CTB) and the tetrazolium (3-[4,5-dimethylthioazol-2-yl]-2,5-diphenyl tetrazolium bromide) (MTT) were used. The membrane integrity after exposure to AGEs was assayed using the lactate dehydrogenase (LDH) assay. When using the CTB assay for evaluation all AGEs were found to reduce the viability compared with the native protein in all three cell lines. Additionally, all AGEs were found to affect the membrane integrity compared with the native protein in all cell lines. When using the MTT assay for evaluation only MG-AGEs were found to cause a decrease in the viability in all cell lines used. The results of the MTT assay in Glc-AGEs treated cells varied between the cell lines. To gain a deeper understanding of the cellular responses after exposure of cells to AGEs, the present study compares results obtained when using the CTB, the MTT or the LDH assay in identically AGE treated cells.

Differential polyamine analogue effects in four human breast cancer cell lines

Polyamine analogues have demonstrated anti-tumour activity in a number of solid tumour models. In the present study we compared the cytotoxicities of three polyamine analogues against four breast cancer cell lines. All cell lines are derived from tumours of women with breast cancer and, although we are sampling just a small number of tumours, they represent a spectrum of the genetic plethora of breast cancers. Cytotoxicity, over a dose range from 0.1 to 100 microM, was evaluated with three different cytotoxicity assays performed in 96-well plates. Comparing the effects of the analogues on polyamine pools with data from the cytotoxicity assays indicates that there was not a direct correlation between polyamine pool depletion and cytotoxicity. Flow cytometry was used to investigate analogue-induced cell death as measured by the appearance of a sub-G(1) peak. Induction of cell death by the analogues differed in the cell lines, however, cell death when induced was apoptotic, as demonstrated by detection of apoptotic bodies with immunofluorescence microscopy of propidium iodide-stained nuclei. Comparing the flow cytometry-derived data and the data from the cytotoxicity assays reveals that the analogues exert their effects by inhibiting cell growth and/or inducing cell death.