An electron paramagnetic resonance study of free radicals in cells

An electron paramagnetic resonance study was performed on cell lines of the following strains: HeLa, 37RC, L, FLC, NRK/RSV, 3T3/SV40.Unsynchronized and synchronized HeLa cells were studied with particular attention paid to the relation between growth and free radical concentration. Free radical levels were shown to be a function of the growth stage and different phases of the cell cycle.     

Influences of clotting factors (thrombin, factor XIII) and of fibronectin on the growth of tumor cells and leukemic cells in vitro

Thrombin, factor XIII and fibronectin were incubated with cultures of mouse sarcoma cells, human cervix carcinoma cells (HeLa cells) and cells of an acute lymphoblastic leukemia. Thrombin induced a significant increase of 3H-thymidine uptake into cells with a 1,5- to 2-fold increase of cell count. The cells of an acute lymphoblastic leukemia showed a similar response to the influence of thrombin. Factor XIII in tumor cells merely induced an increase of 3H-thymidine uptake, the cell count remained constant. The cells of an acute lymphoblastic leukemia showed under the influence of factor XIII a significant increase of cell count and thymidine uptake. HeLa cell growth was optimal at low fibronectin concentrations. Fibronectin concentrations of 1 mg/ml to 3 mg/ml inhibited HeLa and mouse sarcoma cell growth.     

Dimethylfumarate induces cell cycle arrest and apoptosis via regulating intracellular redox systems in HeLa cells

Dimethylfumarate (DMF) is cytotoxic to several kinds of cells and serves as an anti-tumor drug. This study was designed to investigate the effects and underlying mechanism of DMF on cervical cancer cells. HeLa cells were cultured and treated with 0, 50, 100, 150, and 200 μM DMF, respectively. After 24 h, cell growth was evaluated using Cell Counting Kit-8 (CCK-8) assay and the cell cycle was examined using flow cytometry. In addition, cell apoptosis was detected by Annexin V/propidium iodide (PI) staining and the expressions of caspase-3 and poly-ADP-ribose polymerase (PARP) were detected using western blotting. The redox-related factors were then assessed. Furthermore, all of the indicators were detected in HeLa cells after combined treatment of DMF and N-acetyl-l-cysteine (NAC, an oxygen-free radical scavenger). The cell number and cell growth of HeLa were obviously inhibited by DMF in a dose-dependent manner, as the cell cycle was arrested at G0/G1 phase (P?<?0.05). The apoptotic HeLa cells were markedly increased, and the expression levels of caspase-3 and PARP were significantly increased in a DMF concentration-dependent way (P?<?0.05). Meanwhile, loss of △Ψm, increase in reactive oxygen species and O₂ ^·?, and the decrease in catalase activity and glutathione (GSH) level were found after DMF treatment (P?<?0.05). All these changes were significantly attenuated and even completely disappeared by adding NAC (P?<?0.05). In conclusion, the cytotoxicity of DMF on cell proliferation and apoptosis of HeLa cells was mainly related to the intracellular redox systems by depletion of intracellular GSH.     

Electron spin resonance of growing normal and virus-transformed cells

A g = 2.003 ESR signal, attributed to a free radical localized in HeLa cell nuclei and mitochondria but absent in membranes and cytoplasm, has been studied as a function of the culture growth cycle in normal (NRK and 3T3) and virus transformed (NRK/RSV and 3T3/SV40) cells. For both these cell pairs, the signal is higher during the "lag" stage and lower during the "growth" stage. The average specific intensity of the signal in normal cells is about twice that in virus-transformed cells. However, the maximal point of resonance during the lag state is higher in transformed cells than in normal ones. The lag stage in NRK and NRK/RSV cells is much longer than in 3T3 and 3T3/SV40 cells, while the maximal value of the g = 2.003 ESR signal occurs, early in the lag stage of 3T3 and 3T3/SV40 cells and late in the lag stage of NRK and NRK/RSV cells.     

Induction of apoptosis by Centaurea nerimaniae extract in HeLa and MDA-MB-231 cells by a caspase-3 pathway

We investigated the cytotoxic and apoptotic effects of a methanol extract of Centaurea nerimaniae, a plant endemic in Turkey, on HeLa and MDA-MB-231 cells. Eight concentrations of C. nerimaniae extract were applied to cells, and cytotoxic effects were measured using the xCELLigence system. The TUNEL assay was used to assess apoptotic cell death and immunohistochemistry was used to determine active caspase-3 using the effective cytotoxic doses of the extract. Doses of 1.42 mg/ml C. nerimaniae inhibited the growth of HeLa cells and 3.67 mg/ml C. nerimaniae inhibited the growth of MDA-MB-231 cells in a dose- and time-dependent manner. The apoptotic indexes for HeLa and MDA-MB-231 cells were increased significantly compared to control groups. Immunohistochemistry showed that the number of caspase-3 immunostained cells increased in the extract treatment groups for both HeLa and MDA-MB-231 cells. In the MDA-MB-231 cell line, caspase-3 immunostaining was observed in nuclei and/or cytoplasm in the extract treated group. Caspase-3 activation was greater in HeLa cells than in MDA-MB-231 cells. We found that the extract of C. nerimaniae had a strong antiproliferative effect and induced apoptosis via caspase-3; MDA-MB-231 cancer cells were more resistant than HeLa cells.     

Differential activation of Smads in HeLa and SiHa cells that differ in their response to transforming growth factor-beta

We assessed the responsiveness of six human cervical cancer cell lines to transforming growth factor (TGF)-beta with p3TP-lux reporter assay and found that HeLa and SiHa cells were highly responsive to TGF-beta. However, when pSBE4-BV/Luc reporter with four Smad binding elements was used, only the SiHa, not the HeLa, cells showed Smad activation. Smad DNA binding activity was relatively more in SiHa than in HeLa cells upon TGF-beta treatment, and the active complex contained Smad 2 and Smad 4. In 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, HeLa cells treated with 5 ng/ml of TGF-beta for 24 h showed proliferation, whereas SiHa cells showed growth inhibition under the same conditions. TGF-beta treatment resulted in G(0)/G(1) arrest with a reduction in S-phase only in SiHa cells. A chemical inhibitor of Smad activation (SB203580) blocked the growth inhibitory effect of TGF-beta in SiHa, whereas the proliferative response in HeLa was unaffected. TGF-beta-induced translocation of phospho-Smad 2 was relatively less in HeLa than in SiHa cells. MAPK activation occurred within 5 min and persisted up to 15 min upon TGF-beta treatment in HeLa but was negligible in SiHa cells. TGF-beta activated JNK in HeLa, but SiHa cells showed a down-regulation of its activity. When an inhibitor of MAPK (U0126) was used, the TGF-beta-mediated proliferative response in HeLa cells was completely abolished. SB203580 did not affect MAPK activation induced by TGF-beta in HeLa cells. We report for the first time an activation, presumably independent of Smad activation, of TGF-beta-dependent MAPK within 5 min of treatment that resulted in cell cycle progression in a cervical adenocarcinoma cell line, HeLa.     

Comparison of Chlamydia trachomatis serovar L2 growth in polarized genital epithelial cells grown in three-dimensional culture with non-polarized cells

A common model for studying Chlamydia trachomatis and growing chlamydial stocks uses Lymphogranuloma venereum serovar L2 and non-polarized HeLa cells. However, recent publications indicate that the growth rate and progeny yields can vary considerably for a particular strain depending on the cell line/type used, and seem to be partially related to cell tropism. In the present study, the growth of invasive serovar L2 was compared in endometrial HEC-1B and endocervical HeLa cells polarized on collagen-coated microcarrier beads, as well as in HeLa cells grown in tissue culture flasks. Microscopy analysis revealed no difference in chlamydial attachment/entry patterns or in inclusion development throughout the developmental cycle between cell lines. Very comparable growth curves in both cell lines were also found using real-time PCR analysis, with increases in chlamydial DNA content of 400-500-fold between 2 and 36 h post-inoculation. Similar progeny yields with comparable infectivity were recovered from HEC-1B and HeLa cell bead cultures, and no difference in chlamydial growth was found in polarized vs. non-polarized HeLa cells. In conclusion, unlike other C. trachomatis strains such as urogenital serovar E, invasive serovar L2 grows equally well in physiologically different endometrial and endocervical environments, regardless of the host cell polarization state.     

M-CSF上调cyclinD1/D3和CDK2/6的表达促进HeLa细胞增殖

非分泌型巨噬细胞集落刺激因子(M-CSF)的表达在肿瘤的发生发展过程中发挥重要作用,为探讨胞质M-CSF对细胞增殖的影响,采用基因重组技术构建胞内稳定表达M-CSF的HeLa细胞系,以空载体(pCMV/myc/cyto)转染HeLa细胞和未转染HeLa细胞作为对照,MTT法及反义寡核苷酸抑制实验分析M-CSF对细胞增殖的影响,并计算细胞倍增时间,RT-PCR观察胞内M-CSF对G1期细胞周期相关蛋白的影响．结果显示,与对照组比较,转染M-CSF的HeLa细胞倍增时间明显缩短、增殖能力显著增强,M-CSF的特异性反义寡核苷酸能抑制转染M-CSF的HeLa细胞的增殖,且抑制率随着反义寡核苷酸浓度的增高而增强,转染M-CSF 的HeLa细胞的cyclinD1/D3和CDK2/6 mRNA表达显著升高(P < 0.05)．提示：M-CSF可上调cyclinD1/D3和CDK2/6的mRNA表达,促进HeLa细胞的增殖．     

Opposing effects of ERK and p38 MAP kinases on HeLa cell apoptosis induced by dipyrithione

Dipyrithione (2, 2'-dithiobispyridine-1, 1'-dioxide, PTS2), a pyrithione derivate, is highly bactericidal and fungicidal. In this study we examined its apoptotic effect on HeLa cells. PTS2 induced HeLa cell death in a dose and time dependent manner. ERK1/2 and p38 were markedly activated, but little JNK1/2 activation was detected. Suppression of p38 activation by SB203580 reduced the extent of apoptosis of the HeLa cells and also prevented induction of p21, release of cytochrome c, and cleavage of caspase-3 and PARP. Inhibition of ERK1/2 with PD98059 increased apoptosis, indicating that ERK1/2 activation has an anti-apoptotic effect on PTS2-induced HeLa cell apoptosis. PTS2 also inhibited murine sarcoma 180 and hepatoma 22 tumor growth in an animal tumor model. Our findings indicate that PTS2 possesses anti-tumor activity, that caspase-3 and poly (ADP-ribose) polymerase (PARP) are involved in PTS2-induced HeLa cell apoptosis and that ERK1/2 and p38 have opposing effects on this apoptosis.     

Induction of (2'-5')oligoadenylate synthetase in serum-starved HeLa S3 cells by growth factors and its role in growth regulation

When serum-starved HeLa S3 cells were stimulated to proliferate by addition of fetal calf serum (FCS), (2'-5')oligoadenylate synthetase (2-5A synthetase) activity was induced. Although no interferon (IFN) activity was detectable in the HeLa S3 cell-conditioned culture medium after growth stimulation, addition of anti-IFN-beta monoclonal antibody inhibited both the expression of the 2-5A synthetase gene and the production of the enzyme, suggesting that endogenous IFN-beta was involved in 2-5A synthetase induction. Purified preparations of three growth factors, epidermal growth factor, platelet-derived growth factor, and insulin, also induced 2-5A synthetase through IFN-beta. When serum-starved HeLa S3 cells were treated with FCS, DNA synthesis was initiated synchronously, with peaks after 12 and 32 h, although the level of 2-5A synthetase reached a maximum after the first peak of DNA synthesis. Inhibition of 2-5A synthetase induction by anti-IFN-beta antibody enhanced the second, but not the first cycle of DNA synthesis. These results suggested that in HeLa S3 cells, after stimulation with growth factors the IFN/2-5A synthetase system played a role in cell growth negative regulatory mechanisms.     

Growth factor regulated expression of poly(A) binding protein messenger RNA

A 72,000 mol wt protein designated PABP binds to the poly(A)+ track of messenger RNAs with high affinity and has been suggested to play an important role in mRNA metabolism in eucaryotic cells. We have employed a human PABP cDNA probe to study the expression of this gene at the mRNA level in BALB/c3T3 mouse cells under different growth conditions and in exponentially growing HeLa cells throughout the cell division cycle. We describe experiments which establish that in BALB/c3T3 cells the expression of this gene is growth factor regulated. Moreover, the gene behaves like a primary response gene in that its induction in quiescent cells does not require the prior synthesis of other growth factor-regulated proteins. In exponentially growing HeLa cells PABP mRNA is expressed throughout the cell division cycle indicating that the expression of this gene is not limited to a specific phase of the cell cycle.     

The Na+,K+,2Cl- -cotransport system in HeLa cells and HeLa cell mutants exhibiting an altered efflux pathway

We have investigated the characteristics of a transport system in HeLa cells, which turned out to be very similar to a previously described Na+, K+, 2Cl- -cotransport system. For further understanding about the physiological role of the cotransporter, we have mutagenized HeLa cells and selected progeny cells for growth in low potassium (0.2 mM) medium. The selected HeLa cells (LK1) exhibited alterations in the Na+,K+,2Cl- -cotransport system. LK1 cells showed a remarkable reduction of 86Rb+ efflux via the cotransporter when compared to the parental HeLa cells. In contrast, bumetanide-sensitive potassium influx, measured by 86Rb+ uptake, was increased in the LK1 cells (increase in Vmax). Km values of the cotransporter in HeLa cells and LK1 mutants revealed similar properties for 86Rb+ and 22Na+ uptake. In addition, (3H)-bumetanide binding studies were carried out on intact HeLa cells; 1.7 pmol/mg protein (3H)-bumetanide was specifically bound to HeLa parental cells, which could be calculated to a number of 103,000 binding sites/cell. LK1 cells present, 1.44 pmol/mg protein, specifically bound (3H)-bumetanide and, respectively, 137,000 binding sites/cell. The LK1 cells also exhibited an increase in the number of (3H)-ouabain binding sites as well as an increase in the activity of the Na+,K+-ATPase, expressed as a function of ouabain-sensitive 86Rb+ uptake. Furthermore, LK1 cells were different in the concentrations of intracellular Na+ (increases) and K+ (decreases) when compared to the HeLa parental cells. When grown in low K+ medium (0.2 mM K+), protein content and cell volume were increased in the LK1 cells, while the DNA content was not significantly different between both cell lines.     

In vitro study of cytotoxicity by U.V. radiation and differential sensitivity in combination with alkylating agents on established cell systems

The effect of U.V. radiation or alkylating agents, such as actinomycin-D, cycloheximide and mitomycin-C (MMC), was studied on CHO, BHK and HeLa cells. U.V. radiation caused DNA ssb and dsb and were prevented by cycloheximide and actinomycin-D. MMC is known to be cytotoxic in CHO/BHK cells by forming free radical generation. MMC in combination with U.V. radiation enhanced DNA ssb & dsb in these cell types. However, HeLa cells were insensitive to U.V. radiation. This insensitivity to U.V. radiation could be ascribed to the presence of glutathione transferase which is absent in CHO/BHK cell line.     

Benzobijuglone, a novel cytotoxic compound from Juglans mandshurica, induced apoptosis in HeLa cervical cancer cells

A new quinone compound, p-hydroxymethoxybenzobijuglone (HMBBJ), isolated from Juglans mandshurica by bioassay-guided fractionation, showed cytotoxic activity against HeLa cell line. Its chemical structure was determined by NMR and HREIMS spectra. In this paper, its ability to induce apoptosis in HeLa cells was studied for the first time. After treated with HMBBJ, the growth of HeLa cells was inhibited and cells displayed typical morphological apoptotic characteristics. Data from flow cytometry analysis showed that the HeLa cell cycle was arrested in the G2/M phase by HMBBJ, and the apoptotic rate of HeLa cells increased in a dose-dependent manner. Meanwhile, HMBBJ increased the expression of caspase-8, -3 and Bax, decreased the expression of Bcl-2, and lowered the ΔΨ_m. These findings reveal that HMBBJ could efficiently induce HeLa cells apoptosis through mitochondria dependent pathway and activation of the caspase cascade, and it may be a potential chemotherapeutic candidate for the treatment of cancer.     

Antisense depletion of death-associated protein kinase promotes apoptosis

Death-associated protein kinases (DAPK) are serine/threonine protein kinases that have an important role in regulating cell death. In this study two antisense approaches were employed to down-regulate expression of the endogenous DAPK-alpha and DAPK-beta proteins. Transient expression of an antisense DAPK cDNA or antisense morpholino oligonucleotides in HeLa, 3T3, or primary human vascular smooth muscle cells demonstrate that decreased DAPK expression promotes a spontaneous, caspase-mediated apoptosis as evidenced by increased activities of caspases-3 and -9. Clonal HeLa cell lines with attenuated levels of DAPK expression, obtained following selection in the presence of antisense DAPK cDNA, are more sensitive to tumor necrosis factor-induced caspase-mediated apoptosis, and their sensitivity is inversely related to DAPK expression. In contrast, HeLa cells with reduced DAPK expression are moderately resistant to cell death induced by interferon-gamma. This finding is consistent with previous studies showing that DAPK has a role in promoting caspase-independent cell death. Together, these studies demonstrate that the cellular activities of DAPK are critical for antagonizing caspase-dependent apoptosis to promote cell survival under normal cell growth conditions.     

Formation of Viral Ribonucleic Acid and Virus in Cells that are Permissive or Nonpermissive for Murine Encephalomyelitis Virus (GDVII)

GDVII virus growth in BHK-21 cells, a permissive host for the virus, resembled productive infections with other picornaviruses. Virus yields ranged from 100 to 600 plaque-forming units (PFU)/cell. Virus replication in HeLa cells, a nonpermissive host for GDVII virus, was characterized by virus yields of only 0.1 to 5 PFU/cell. Similar low yields of virus have been obtained from HeLa cells at all multiplicities of input up to 6,000 per cell. The progeny particles from HeLa cells were, like the infecting particles, restricted in the HeLa cell host. Despite the great difference in final yields of virus from BHK-21 and HeLa cells, the times when maximal yields were reached were similar. GDVII virus stock grown in BHK-21 cells was designated HeLa(-). A variant of GDVII virus which is capable of extensive growth in HeLa cells was obtained. This variant, designated HeLa(+) GDVII virus, was passaged serially in HeLa cells. Virus yields of 50 to 150 infective virus particles per cell were obtained from infection of HeLa cells with HeLa(+) GDVII virus. The major species of HeLa(+) virus-specific ribonucleic acid (RNA) produced was single stranded and sedimented with an S value of 35S. The rate of accumulation of HeLa(+) virus-specific RNA in HeLa cell cultures was about four times that of HeLa(-) RNA. The amount of virus-specific HeLa(+) RNA formed in HeLa cells was several-fold greater than that of HeLa(-) RNA. With HeLa(-) parent GDVII virus undergoing productive replication in BHK-21 cells or abortive replication in HeLa cells, the major species of virus-specific RNA produced was single stranded and sedimented with an approximate S value of 35S. The amount of HeLa(-) virus-specific RNA extracted from BHK-21 cells was several-fold greater than the amount obtained from HeLa cells.     

A free radical initiator, 2,2'-azobis (2-aminopropane) dihydrochloride enhances hyperthermia-induced apoptosis in human uterine cervical cancer cell lines

Hyperthermia-induced apoptosis and its enhancement in the presence of a temperature-dependent free radical initiator, 2,2'-azobis (2-aminopropane) dihydrochloride (AAPH) were examined in human uterine cervical cancer cell lines, CaSki and HeLa. When both cell lines were treated with hyperthermia at 44°C for 60 min, minimal apoptosis was observed. When combined with nontoxic AAPH (50 mM), significant enhancement of apoptosis was observed, where the initial rate of free radical formation was about twice as high than that at 37°C. Augmentation of the growth delay, lipid peroxidation (LPO), activation of caspase-3 and increase in [Ca₂₊]i were also observed after the combined treatment. A water-soluble vitamin E, Trolox, blocked the increase in [Ca₂₊]i and an intracellular Ca₂₊ chelator, BAPTA-AM, prevented the DNA fragmentation induced by the combination. Cytochrome c release was also revealed by fluorescence microscopy. However, no significant change in mitochondrial membrane potential and expression of Bax and Bcl-2 was observed. A slight increase in Fas expression was observed only in CaSki cells after the combined treatment. These results indicate that hyperthermia and AAPH induce enhanced apoptosis and subsequent cell killing via two pathways; a pathway dependent on increase in LPO and [Ca₂₊]i, and a pathway associated with cytochrome c release and subsequent caspase activation without changes of mitochondrial membrane potential and Bax/Bcl-2 expression in these cell lines. Since it is known that cancer cells are generally resistant to physical and chemical stress-induced apoptosis, free radical generators like AAPH appear to be a useful thermosensitizer for hyperthermic cancer therapy.     

组织专一性表达自杀基因治疗人结肠癌的研究

构建了以癌胚抗原(CEA)基因启动子控制的HSV-TK和ECCD的表达质粒PCEA-TK和pCEA-CD. 将它们分别与pSV2-neo共转染人结肠癌细胞株LoVo和人宫颈癌细胞株HeLa. G418筛选得到细胞克隆LoVo/CEA-TK、toVo/CEA-CD、HeLa/CEA-TK和HeLa/CEA-CD. 与野生型LoVo细胞相比, LoVo/CEA-TK和LoVo/CEA-CD形态无明显改变, 生长曲线也相似, 但对GCV或5-FC的细胞毒的敏感性分别提高了2000倍或700倍.而HeLa/CEA-TK(或HeLa/CEA-CD)仍对低浓度GCV(或5-FC)不敏感. 以上结果显示了应用组织专一性表达的自杀基因治疗人结肠癌的可能性.     

Investigations on Antioxidant,Antiproliferative and COX‐2 Inhibitory Potential of Alkaloids from Anthocephalus cadamba (Roxb.) Miq. Leaves

In the present study, an ayurvedic medicinal plant, Anthocephalus cadamba (Roxb .) Miq . commonly known as ‘Kadamb’ was explored for its potential against oxidative stress and cancer. The fractions namely AC‐4 and ACALK (alkaloid rich fraction) were isolated from A. cadamba leaves by employing two different isolation methods and evaluated for their in vitro antioxidant and antiproliferative activity. The structure of the isolated AC‐4 was characterized tentatively as dihydrocadambine by using various spectroscopic techniques such as ESI‐QTOF‐MS, ¹H‐ and ¹³C‐NMR, DEPT, COSY, HMQC, and HMBC. Results of various antioxidant assays viz. 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ABTS cation radical, superoxide anion radical scavenging, and plasmid nicking assay demonstrated that both the fractions viz. AC‐4 and ACALK possess ability to scavenge DPPH, ABTS radicals and effectively protected plasmid pBR322 DNA from damage caused by hydroxyl radicals. Further, when both fractions were evaluated for their potential to suppress growth of HeLa and COLO 205 cells, only ACALK fraction showed antiproliferative effects. ACALK exhibited GI₅₀ of 205.98 and 99.54 μg/ml in HeLa and COLO 205 cell lines, respectively. Results of Hoechst staining in cervical carcinoma (HeLa) cells confirmed that ACALK induced cell death in HeLa cells via apoptotic mode. Both the fractions also inhibited COX‐2 enzyme activity.