Cell growth

About: Cell growth is a research topic. Over the lifetime, 104237 publications have been published within this topic receiving 3751303 citations. The topic is also known as: GO:0016049 & cellular growth.

Fabrication and surface modification of macroporous poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture.

Abstract: The fabrication and surface modification of a po- rous cell scaffold are very important in tissue engineering. Of most concern are high-density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L- lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for mea- suring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N-containing groups and positive charged groups also were incorporated into the sample surface. A low-temperature treatment was used to maintain the plasma-modified surface properties ef- fectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 m are suitable for human skin fibroblast cell growth. Cell seeding efficiency was main- tained at above 99%, which is better than the efficiency achieved with the common method of prewetting by etha- nol. The plasma-treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 438-446, 2002

Apoptosis Primarily Accounts for the Growth-inhibitory Properties of Sulindac Metabolites and Involves a Mechanism That Is Independent of Cyclooxygenase Inhibition, Cell Cycle Arrest, and p53 Induction

Abstract: Sulindac causes regression of and prevents recurrence of colonic adenomas in patients with familial adenomatous polyposis. Although cell cycle arrest and apoptosis have been proposed, the mechanism of action is poorly understood. In this study, we characterized the growth-inhibitory effects of active metabolites of sulindac in cultured colon adenocarcinoma cells by determining the contribution of apoptosis and cell cycle arrest and the requirement for cyclooxygenase (COX) inhibition and p53 involvement and compared the effects of sulindac metabolites with the chemotherapeutic drug, 5-fluorouracil (5-FU). Time course and dose-response experiments demonstrated that increased apoptosis paralleled the growth-inhibitory effects of the sulfide and sulfone. A relationship among a series of nonsteroidal anti-inflammatory drugs was observed between potency for growth inhibition and ability to induce apoptosis but not potency to inhibit COX. For example, the sulfone was at least 5000-fold less potent than the sulfide for inhibiting COX but only 6.5-fold less potent for inducing apoptosis. Moreover, the prostaglandin analogue, dimethyl-prostaglandin E2, failed to reverse the apoptosis-inducing effects of the sulfide. Sulindac metabolites caused G1 cell cycle arrest in proliferating cells but were comparably effective in nonproliferating cells. In contrast, 5-FU treatment was less effective in nonproliferating cells. Combined treatment with sulindac metabolites and 5-FU did not result in an additive apoptotic response. Treatment of cells with 5-FU increased p53 protein levels, whereas sulindac metabolites did not induce expression. Saos-2 cells, which lack p53, responded to sulindac metabolites but not 5-FU. These results show that apoptosis primarily contributes to growth inhibition by sulindac metabolites. The biochemical pathway does not require COX inhibition or p53 induction and appears to be fundamentally different from the apoptotic response to 5-FU.

Mast Cells Enhance T Cell Activation: Importance of Mast Cell Costimulatory Molecules and Secreted TNF

Abstract: We recently reported that mast cells stimulated via FceRI aggregation can enhance T cell activation by a TNF-dependent mechanism. However, the molecular mechanisms responsible for such IgE-, Ag- (Ag-), and mast cell-dependent enhancement of T cell activation remain unknown. In this study we showed that mouse bone marrow-derived cultured mast cells express various costimulatory molecules, including members of the B7 family (ICOS ligand (ICOSL), PD-L1, and PD-L2) and the TNF/TNFR families (OX40 ligand (OX40L), CD153, Fas, 4-1BB, and glucocorticoid-induced TNFR). ICOSL, PD-L1, PD-L2, and OX40L also are expressed on APCs such as dendritic cells and can modulate T cell function. We found that IgE- and Ag-dependent mast cell enhancement of T cell activation required secreted TNF; that TNF can increase the surface expression of OX40, ICOS, PD-1, and other costimulatory molecules on CD3 + T cells; and that a neutralizing Ab to OX40L, but not neutralizing Abs to ICOSL or PD-L1, significantly reduced IgE/Ag-dependent mast cell-mediated enhancement of T cell activation. These results indicate that the secretion of soluble TNF and direct cell-cell interactions between mast cell OX40L and T cell OX40 contribute to the ability of IgE- and Ag-stimulated mouse mast cells to enhance T cell activation.

Nrf2 Enhances Cell Proliferation and Resistance to Anticancer Drugs in Human Lung Cancer

Abstract: Purpose: NF-E2-related factor 2 (Nrf2), a key transcription regulator for antioxidant and detoxification enzymes, is abundantly expressed in cancer cells. In this study, therefore, the role of Nrf2 in cancer cell proliferation and resistance to anticancer drugs was investigated. Experimental Design: We used three human lung cancer cell lines with different degrees of Nrf2 activation: Nrf2 was highly activated in A549 cells, slightly activated in NCI-H292 cells, and not activated in LC-AI cells under unstimulated conditions. Result: A549 cells showed higher resistance to cisplatin compared with NCI-H292 and LC-AI cells. The resistance to cisplatin was significantly inhibited in A549 but not in NCI-H292 or LC-AI cells by knockdown of Nrf2 with its specific small interfering RNA (Nrf2-siRNA). The cell proliferation was also most prominently inhibited in A549 cells by treatment with Nrf2-siRNA. In A549 cells, the expression of self-defense genes, such as antioxidant enzymes, phase II detoxifying enzymes, and drug efflux pumps, was significantly reduced by Nrf2-siRNA concomitant with a reduction of the cellular glutathione level. The degree of DNA crosslink and apoptosis after treatment with cisplatin was significantly elevated in A549 cells by Nrf2-siRNA. Knockdown of Nrf2 arrested the cell cycle at G 1 phase with a reduction of the phosphorylated form of retinoblastoma protein in A549 and NCI-H292 cells but not in LC-AI cells. Conclusion: These results indicate that the Nrf2 system is essential for both cancer cell proliferation and resistance to anticancer drugs. Thus, Nrf2 might be a potential target to enhance the effect of anticancer drugs.

E2F3 activity is regulated during the cell cycle and is required for the induction of S phase

Abstract: Previous work has demonstrated the important role of E2F transcription activity in the induction of S phase during the transition from quiescence to proliferation. In addition to the E2F-dependent activation of a number of genes encoding DNA replication activities such as DNA Pol a, we now show that the majority of genes encoding initiation proteins, including Cdc6 and the Mcm proteins, are activated following the stimulation of cell growth and are regulated by E2F. The transcription of a subset of these genes, which includes Cdc6, cyclin E, and cdk2, is also regulated during the cell cycle. Moreover, whereas overall E2F DNA-binding activity accumulates during the initial G1 following a growth stimulus, only E2F3-binding activity reaccumulates at subsequent G1/S transitions, coincident with the expression of the cell-cycle-regulated subset of E2F-target genes. Finally, we show that immunodepletion of E2F3 activity inhibits the induction of S phase in proliferating cells. We propose that E2F3 activity plays an important role during the cell cycle of proliferating cells, controlling the expression of genes whose products are rate limiting for initiation of DNA replication, thereby imparting a more dramatic control of entry into S phase than would otherwise be achieved by post-transcriptional control alone.