Affect Growth Inhibition Research Articles

SOX2 is a promising predictor of relapse and death in advanced stage high-grade serous ovarian cancer patients with residual disease after debulking surgery

ABSTRACT The transcription factor SOX2 is a well-established and important stem cell marker. Its role in cancer biology remains unclear, but it has been proposed to also be a marker of cancer stem cells. We investigated the role of SOX2 protein expression in women with high-grade serous ovarian cancer (HGSOC) to determine its potential prognostic and treatment predictive value. We constructed a tissue microarray of 130 advanced stage HGSOC tumors with an average of 6 cores each, stained for SOX2 protein expression and evaluated survival outcomes. We also treated two HGSOC cell lines with carboplatin and paclitaxel and measured SOX2 expression by RT-PCR and immunoblotting at different doses and time-points. Among patients with non-radical debulking surgery overall and progression-free survival were shorter for patients with SOX2 positive tumors (mean 26 vs. 39 months, log-rank test: p = .0076, and mean 14 vs. 19 months, p = .055, respectively). Knockdown of SOX2 in cell lines did not affect growth inhibition following chemotherapy treatment. Our results show that SOX2 has a strong prognostic potential among HGSOC patients with residual tumor tissue after debulking surgery and suggest that SOX2 expressing cells remaining after non-radical debulking surgery may constitute a subpopulation of cancer stem cells with greater tumor-initiating potential.

Transcriptional Analysis of Chlorella Pyrenoidosa Exposed to Bisphenol A.

Bisphenol A (BPA) is the raw material of 71% of polycarbonate-based resins and 27% of epoxy-based resins which are used for coating metal-based food and beverage cans. Meanwhile, it is taken into account as a typical environmental pollutant. Hormesis may occur in algae exposed to BPA. In this study, the effects of BPA on Chlorella pyrenoidosa were assessed based on growth inhibition and transcriptome analysis. We have focused on two exposure scenarios as follows: (1) exposure to a low stimulation concentration (0.1 mg.L−1, 19.35% promotion in cell density on the 3rd day); (2) exposure to a high inhibition concentration (10 mg.L−1, 64.71% inhibition in cell density on the 3rd day). Transcriptome analysis showed enrichment in nucleotide transport, single-organism transport, cellular respiration. Among them, adenosine triphosphate (ATP) synthase and Nicotinamide adenine dinucleotide (NADH) dehydrogenase were upregulated under 0.1 mg.L−1 BPA treatment. These changes enhanced the physiological and energy metabolic pathways of C. pyrenoidosa, thereby stimulating cell proliferation. At exposure to the high BPA, severe inhibited changes in the expression levels of several pathways were observed, which were related to tricarboxylic acid (TCA) cycle, glycolysis, fatty acid metabolism, oxidative phosphorylation, and photosynthesis. Therefore, BPA could negatively affect growth inhibition through the multiple energy metabolism processes. These results may result in a deeper insight into BPA-induced biphasic responses in algae, and provide vital information to assess the potential ecological risks of exposure to BPA in an aquatic ecosystem.

Combination of SNX-2112 with 5-FU exhibits antagonistic effect in esophageal cancer cells.

The low efficacy of single-drug chemotherapy forms the basis for combination therapy in esophageal squamous cell carcinoma. SNX-2112, a selective heat shock protein 90 (Hsp90) inhibitor, was recently reported as being effective in combination with cisplatin and paclitaxel. In this study, we investigated the effect of SNX-2112 in combination with 5-fluorouracil (5-FU), another first-line anticancer drug, in esophageal cancer. Unexpectedly, tetrazolium assay revealed that the combination of SNX-2112 with 5-FU exhibited antagonistic effect. Flow cytometry revealed that the SNX-2112 and 5-FU combination greatly decreased the number of G2/M cells compared to SNX-2112-only treatment in Eca‑109 cells. This effect might be related to the altered mRNA level of cyclin-related genes including cyclinD1, Chk2 and Cdk4. Further, 5-FU attenuated SNX-2112-induced apoptosis by decreasing poly(ADP-ribose) polymerase (PARP) cleavage and inactivating caspase-3, -8 and -9. Additionally, 5-FU suppressed the SNX-2112-induced decrease of mitochondrial membrane potential. Moreover, 5-FU partly recovered Hsp90 client proteins, including Akt, p-Akt, inhibitor of κB kinase (IKK)α, extracellular signal-regulated kinase (ERK)1/2, and glycogen synthase kinase (GSK)-3β, which SNX-2112 had downregulated. Taken together, this is the first report that the combination of SNX-2112 with 5-FU exhibited antagonistic effect in esophageal cancer cells by affecting growth inhibition, cell cycle, apoptosis, and Hsp90 client proteins, suggesting that care is required in the clinical application of combined SNX-2112 and 5-FU.

Domain exchange at the 3’ end of the gene encoding the fratricide meningococcal two-partner secretion protein A

BackgroundTwo-partner secretion systems in Gram-negative bacteria consist of an outer membrane protein TpsB that mediates the secretion of a cognate TpsA protein into the extracellular milieu. TpsA proteins have diverse, often virulence-related functions, and some of them inhibit the growth of related bacteria. In Neisseria meningitidis, several functions have been attributed to the TpsA proteins. Downstream of the tpsB and tpsA genes, several shorter tpsA-related gene cassettes, called tpsC, are located interspersed with intervening open-reading frames (IORFs). It has been suggested that the tpsC cassettes may recombine with the tpsA gene as a mechanism of antigenic variation. Here, we investigated (i) whether TpsA of N. meningitidis also has growth-inhibitory properties, (ii) whether tpsC cassettes recombine with the tpsA gene, and (iii) what the consequences of such recombination events might be.ResultsWe demonstrate that meningococcal TpsA has growth-inhibitory properties and that the IORF located immediately downstream of tpsA confers immunity to the producing strain. Although bioinformatics analysis suggests that recombination between tpsC cassettes and tpsA occurs, detailed analysis of the tpsA gene in a large collection of disease isolates of three clonal complexes revealed that the frequency is very low and cannot be a mechanism of antigenic variation. However, recombination affected growth inhibition. In vitro experiments revealed that recombination can be mediated through acquirement of tpsC cassettes from the environment and it identified the regions involved in the recombination.ConclusionsMeningococcal TpsA has growth-inhibitory properties. Recombination between tpsA and tpsC cassettes occurs in vivo but is rare and has consequences for growth inhibition. A recombination model is proposed and we propose that the main goal of recombination is the collection of new IORFs for protection against a variety of TpsA proteins.

The Root Cap Determines Ethylene-Dependent Growth and Development in Maize Roots

Besides providing protection against mechanical damage to the root tip, the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development. The transduction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize. Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment. Reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again. In contrast, the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative RT-PCR results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene. From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

Effects of a selective cyclooxygenase-2 inhibitor, nimesulide, on the growth of ovarian carcinoma in vivo

New therapies against cancer are based on targeting cyclooxygenase-2 (COX-2). Whether COX-2 inhibitor therapy would be beneficial in the prevention and/or treatment of ovarian cancer still remains unclear. This study was designed to investigate whether nimesulide, a COX-2 selective inhibitor, could suppress tumor growth in implanted ovarian carcinoma mice and to explore the molecular mechanisms. Human ovarian SKOV-3 carcinoma cells xenograft-bearing mice were treated with nimesulide 62.5 mg/kg or 250 mg/kg alone i.g., daily for 21 days. Microvessel density (MVD) of ovarian carcinoma was determined with anti-CD(34) as the label. Prostaglandin E2 (PGE2) levels were also determined by ELISA. In addition, the expression of COX-2 and COX-1 at protein and mRNA levels in the control groups was also detected by immunohistochemistry and reverse-transcription polymerase chain reaction (RT-PCR). Nimesulide treatment showed a dose-dependent growth-inhibitory effect of human ovarian SKOV-3 tumors. The inhibitory rates in nimesulide 62.5 mg/kg group and 250 mg/kg group were 20.40% and 50.55% respectively, however, which is not significant statistically compared with that of control group (P > 0.05). In treatment groups, nimesulide significantly reduced intratumor PGE2 levels (all, P < 0.01). Microvessel densities in treatment groups were 61.20 +/- 1.67 (62.5 mg/kg) and 66.27 +/- 1.20 (250 mg/kg), which are significant statistically compared with that of control group (79.97 +/- 1.07) (all, P < 0.01). However, COX-1, not COX-2, mRNA, and protein levels are elevated in tumor tissues. Nimesulide decreased microvessel density is associated with the reduction of PGE2 levels but without affecting growth inhibition and the expression of COX-2. Importantly, tumor growth implanted in SKOV-3 mice was not significantly attenuated suggesting that COX-1 in ovarian carcinoma tissue also has an important role in tumor growth. These findings may implicate COX-1 as a suitable target for the treatment of ovarian cancer.

The effect of ultrasonic irradiation on doxorubicin-induced cytotoxicity in three human bladder cancer cell lines

Although ultrasonic irradiation has been proven to increase membrane permeability and enhance chemotherapeutic cytotoxicity in a number of cell lines, this effect has never been demonstrated in bladder cancer cells. Bladder cancer may offer a unique setting for ultrasound enhancement of chemotherapy, since intravesicular rather than intravenous administration of chemotherapy is used in superficial cases. The aim of this study was to investigate whether a non-toxic dose of ultrasound could increase membrane permeability, and potentiate the cytotoxicity of doxorubicin to three human bladder carcinoma cell lines (TCC–SUP, T24, and RT4) in vitro. An EuTDA–Efflux assay, which measures the amount of a chemical that is allowed to seep out of labeled cells, was used to analyze membrane permeability, and an MTS assay, which directly measures cell viability, was used to determine the effect of chemotherapy on cells after they were treated with a variety of doxorubicin concentrations and ultrasonic exposures. Ultrasound treatment for 5min and 10min at an intensity of approximately 0.3W/cm2 resulted in a significant increase in EuTDA efflux in all three cell lines. However, no ultrasonic enhancement of doxorubicin growth inhibition in these human bladder carcinoma cells was observed. This suggests that either ultrasound does not increase doxorubicin uptake by the cell or that doxorubicin uptake is increased but in insufficient amounts to affect growth inhibition. Further investigation should focus on explaining these results.

Retinoids Chemosensitize Ovarian Cancer Cell Lines to Cisplatin Independent of Nuclear Receptors and p53

Treatment of ovarian cancer with cisplatin-based chemotherapy is highly toxic and is often followed by cancer recurrence. Repeated treatments with cisplatin frequently result in the development of resistance to this drug. Drugs with low toxicity that could enhance the tumor cell killing effects of cisplatin could potentially reduce the toxicity and enhance the efficacy of cisplatin. The mechanism of cell kill by cisplatin is partially due to induction of apoptosis through the p53 pathway. Retinoids can regulate apoptosis through nuclear retinoic acid receptors, but the role of p53 in the mechanism varies with the individual retinoid and cell type. The objective of this study was to evaluate the potential of receptor-active and –independent retinoids as chemosensitization of ovarian cancer cell lines with different p53 status. The growth of two ovarian cancer cell lines, OVCAR-3 that has wild type p53 and Caov-3 that has mutant type, was evaluated in the presence and absence of various combinations of cisplatin, a series of retinoids and a chemical inhibitor of p53 transactivation activity (pifithrinα). Both receptor active and receptor independent retinoids chemosensitized the two cell lines to cisplatin. PFTα partially attenuated growth inhibition by cisplatin, slightly enhanced the growth inhibition of retinoids and did not affect growth inhibition when retinoids were used in combination with cisplatin. RNase protection demonstrated that PFTα did not alter retinoid effects on p53 regulated genes. In conclusion, retinoids chemosensitize both sensitive and resistant ovarian cancer cells to cisplatin through mechanisms independent of nuclear retinoid receptors and p53.

Nuclear factor YY1 inhibits transforming growth factor beta- and bone morphogenetic protein-induced cell differentiation.

Smad proteins transduce transforming growth factor beta (TGF-beta) and bone morphogenetic protein (BMP) signals that regulate cell growth and differentiation. We have identified YY1, a transcription factor that positively or negatively regulates transcription of many genes, as a novel Smad-interacting protein. YY1 represses the induction of immediate-early genes to TGF-beta and BMP, such as the plasminogen activator inhibitor 1 gene (PAI-1) and the inhibitor of differentiation/inhibitor of DNA binding 1 gene (Id-1). YY1 inhibits binding of Smads to their cognate DNA elements in vitro and blocks Smad recruitment to the Smad-binding element-rich region of the PAI-1 promoter in vivo. YY1 interacts with the conserved N-terminal Mad homology 1 domain of Smad4 and to a lesser extent with Smad1, Smad2, and Smad3. The YY1 zinc finger domain mediates the association with Smads and is necessary for the repressive effect of YY1 on Smad transcriptional activity. Moreover, downregulation of endogenous YY1 by antisense and small interfering RNA strategies results in enhanced transcriptional responses to TGF-beta or BMP. Ectopic expression of YY1 inhibits, while knockdown of endogenous YY1 enhances, TGF-beta- and BMP-induced cell differentiation. In contrast, overexpression or knockdown of YY1 does not affect growth inhibition induced by TGF-beta or BMP. Accordingly, YY1 does not interfere with the regulation of immediate-early genes involved in the TGF-beta growth-inhibitory response, the cell cycle inhibitors p15 and p21, and the proto-oncogene c-myc. In conclusion, YY1 represses Smad transcriptional activities in a gene-specific manner and thus regulates cell differentiation induced by TGF-beta superfamily pathways.

Transforming growth factor-β-mediated mast cell migration depends on mitogen-activated protein kinase activity

Transforming growth factor-β (TGF-β) isoforms regulate numerous cellular functions through binding to receptors with intrinsic serine/threonine kinase activity that transduce the intracellular signals via activation of Smad proteins. In this study, we examined the signalling pathways involved in TGF-β1-mediated growth inhibition and migration in a human mast cell line, HMC-1. TGF-β1 evoked optimal migration at 40 fM, whereas maximal growth inhibition was obtained at 400 pM. Protein tyrosine kinase inhibitors completely inhibited TGF-β1-mediated migration, without affecting the antimitogenic response. Smad2 was phosphorylated upon TGF-β1 treatment, both in the absence and presence of genistein. The mitogen-induced extracellular kinase (MEK) inhibitor, PD98059, blocked the migratory response without affecting growth inhibition. In contrast, the p38 MAP kinase inhibitor, SB203580, had no significant effect on either migration or growth inhibition. These results indicate that different signalling pathways mediate TGF-β1-induced migration and growth inhibition in HMC-1 cells, where the migration involves MEK activity.

Structural determinants of antiproliferative activity of heparin on pulmonary artery smooth muscle cells.

In addition to its anticoagulant properties, heparin (HP), a complex polysaccharide covalently linked to a protein core, inhibits proliferation of several cell types including pulmonary artery smooth muscle cells (PASMCs). Commercial lots of HP exhibit varying degrees of antiproliferative activity on PASMCs that may due to structural differences in the lots. Fractionation of a potent antiproliferative HP preparation into high and low molecular weight components does not alter the antiproliferative effect on PASMCs, suggesting that the size of HP is not the major determinant of this biological activity. The protein core of HP obtained by cleaving the carbohydrate-protein linkage has no growth inhibition on PASMCs, demonstrating that the antiproliferative activity resides in the glycosaminoglycan component. Basic sugar residues of glucosamine can be replaced with another basic sugar, i.e., galactosamine, without affecting growth inhibition of PASMCs. N-sulfonate groups on these sugar residues of HP are not essential for growth inhibition. However, O-sulfonate groups on both sugar residues are essential for the antiproliferative activity on PASMCs. In whole HP, in contrast to an earlier finding based on a synthetic pentasaccharide of HP, 3-O-sulfonation is not critical for the antiproliferative activity against PASMCs. The amounts and distribution of sulfonate groups on both sugar residues of the glycosaminoglycan chain are the major determinant of antiproliferative activity.

Adenosine inhibits cell division and promotes neurite extension in PC12 cells.

Low concentrations (10-50 microM) of adenosine (EC50 = 17 microM) or chloroadenosine (EC50 = 23 microM) prevent the division of PC12 cells. This inhibition is not mimicked by guanosine, inosine, 3',5' dideoxyadenosine, phenylisopropyladenosine, or adenylylimidodiphosphate. The growth inhibition is not relieved by addition of uridine or deoxycytidine, nor is it potentiated by homocysteine thiolactone. Inhibition of adenosine uptake does not inhibit adenosine-dependent growth arrest. PC12 variants that are deficient in adenosine kinase are as sensitive as wild-type cells to the growth-inhibitory effects of adenosine. These experiments suggest that adenosine prevents cell division at an adenosine receptor rather than acting after being metabolically altered. The adenosine receptor that inhibits cell division does not appear to be the adenosine receptor that stimulates adenylate cyclase for these reasons: (1) phenylisopropyladenosine, which is a potent agonist of this receptor, does not inhibit cell division; (2) 3',5' dideoxyadenosine does not antagonize the effect of adenosine on cell division; and (3) theophylline does not affect growth inhibition by adenosine. Thus, these experiments suggest the existence of a second adenosine receptor that can inhibit cell division. Adenosine also promotes the morphological differentiation of PC12 cells. In the presence of the adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenosine (EHNA), adenosine causes the formation of short neurites (one-half to one and one-half cell diameters in length). Adenosine also increases the rate of neurite formation of both long and short neurites in response to NGF.