SW982 cells are characterized by expression of inflammatory cytokine and matrix metalloproteinase (MMP) genes and by their response to dexamethasone at different cell densities. They express genes encoding interleukin (IL)-1β; IL-6; transforming growth factor–β; intercellular adhesion molecule–1; cycloxygenase (COX)-2; and MMPs, including MMP-1, MMP-2, MMP-13, and MT1-MMP; tissue inhibitor of metalloproteinase–2; and a disintegrin and metalloproteinase with thrombospondin motifs–4. Expression of all the genes examined was induced with 2 ng/ml IL-1β at low cell density. The cells, however, failed to express tumor necrosis factor–α, COX-1, and MMP-9, regardless of the presence of IL-1β. Dexamethasone significantly reduced IL-1β, IL-6, COX-2, and MMP-1 expression at high cell density. The results suggest that SW982 cells are a useful tool for studying the expression of inflammatory cytokine or MMP genes.

The cytotoxic activity of short-chain (C₂) ceramide was evaluated in human intestinal carcinoma cells grown as multicellular tumor spheroids versus the same cells cultured as monolayers under closely comparable conditions. A decrease in cell number was seen in monolayer cultures of HT-29, Caco-2, and HRT-18 cells, with an EC₅₀ (concentration for half-maximal toxicity) of between 13 and 23 μM. However, when the same cells were grown in the multicellular spheroid format, C₂ was markedly less potent in reducing cell number, with an EC₅₀ of between 44 and 63 μM, representing a 1.9- to 4.9-fold decrease in its potency. The chemotherapeutic agents 5-fluorouracil and cisplatin were equally potent against spheroids and monolayer cultures, indicating that although drug access is a problem in conventionally grown tumor spheroids it is not a problem for spheroids grown under the conditions used in this study. Our results suggest that although ceramide is capable of inducing cell death in intestinal carcinoma cells grown in spheroid culture, its cellular toxicity is constrained by influences that are independent of drug access and may be the consequence of the altered cellular relationships. Carcinoma cell populations show an intrinsically decreased responsiveness to the effects of ceramide when they are grown in a three-dimensional culture format.

Single-nucleotide polymorphisms (SNPs) are differences in the nucleotide sequence of a specific gene from different individuals. The frequency at which SNPs occur varies among individuals, is gene dependent, and may be influenced by the aging process or by mechanisms that result in cell transformation. Urokinase-plasminogen activator (uPA) is a serine protease that is important in embryonic development, aging, and the onset of pathogenic conditions. The frequency of SNP and the stability of the SNPs in the uPA gene have not been defined with regard to processes that are associated with cellular aging or transformation. In this study, the complete nucleotide sequence has been determined for the gene encoding uPA from 26 human diploid kidney cell lines. The frequency of SNP occurrence within the uPA gene and whether this frequency changed during cellular aging, or after cell transformation, were determined. The results demonstrated three donor-dependent SNPs. One SNP was located at base pair 422, which is in the region of the gene responsible for encoding the high–molecular weight domain of uPA (HMW-uPA). The other SNPs were located at base pairs 691 and 822, both of which are in the region of the gene responsible for encoding the low–molecular weight domain of uPA (LMW-uPA). Single-nucleotide polymorphisms were not detected in the portion of the gene responsible for encoding the uPA secretion signal. Leucine or proline would be encoded at amino acid 141 of HMW-uPA as the result of an SNP at base pair 422. The SNP detected at base pair 691 would encode for lysine or glutamine at amino acid 231 of LMW-uPA. The SNP detected at base pair 822 would not change the encoded asparagine located at position 274 of the protein. The SNPs identified in this study were donor dependent and were not altered during cellular aging, or by changes in karyology due to spontaneous transformation of the cell line. These results demonstrate that the integrity of the uPA gene is stable and not subject to alterations that accompany cell aging or transformation.

We investigated the effects of 6- and 10-T static magnetic fields (SMFs) on the expression of protooncogenes using Western blot immunohybridization methods. We used a SMF exposure system, which can expose cells to a spatially inhomogeneous 6 T with a strong magnetic field (MF) gradient (41.7 T/m) and a spatially homogeneous 10 T of the highest magnetic flux density in this experiment. HL-60 cells exposed to either 6- or 10-T SMF for periods of 1 to 48 h did not exhibit remarkable differences in levels of c-Myc and c-Fos protein expression, as compared with sham-exposed cells. In contrast, c-Jun protein expression increased in HL-60 cells after exposure to 6-T SMF for 24, 36, 48, and 72 h. These results suggest that a homogeneous 10-T SMF does not alter the expression of the c-jun, c-fos, and c-myc protooncogenes. However, our observation that exposure to a strong MF gradient induced c-Jun expression suggests that a strong MF gradient may have significant biological effects, particularly regarding processes related to an elevation of c-jun gene expression.

Inter–simple sequence repeat (ISSR) primers designed to anneal to microsatellites were used to obtain deoxyribonucleic acid (DNA) fingerprint profiles to distinguish among 16 established insect cell lines derived from an assortment of lepidopteran, dipteran, and coleopteran species. Three different levels of cell line comparison were made: (1) between parents and their clones, (2) among cell lines derived from different tissues from the same species, and (3) among cell lines derived from different insect species. Of the 16 repeat oligonucleotide primers used in this study, nine primers generated several unique markers to distinguish between parental cell lines and their clones. Four of the 16 primers also generated DNA profiles with a number of unique bands, enabling the distinction among cell lines derived from specific tissues from the same species. In addition, ISSR-generated DNA profiles provided the greatest number of unique markers to distinguish easily among insect cell lines derived from different species.

Human proximal tubular (PT) epithelial cells were isolated from urine and monoclonally cultured as monolayers for 1 wk, after which they were subcultured between two layers of collagen gel, designated a “collagen gel sandwich.” Under these culture conditions, PT cells formed three-dimensional tubular structures exhibiting distinct polarized cell morphology. Scanning and transmission electron microscopic studies showed that they bore numerous microvilli at the apical surface and that they closely contacted the collagen gel at the basal surface. These studies indicate that PT cells exfoliated in urine still exhibit the potential to proliferate and form organized structures mimicking in vivo tubules. Because of the current lack of useful culture systems for human tubular epithelial cells originating from kidney tissue, we suggest that this unique culture system using voided PT cells in urine could open up new avenues to study not only the mechanisms of morphogenesis but also the physiology of human PT cells.

In situ collagen gelation is a method that combines a static three-dimensional culture technique with rotating bioreactors. This method was designed for large dense tissue engineering ex vivo. To challenge the current limitations on size, we combined the static collagen gel embedding method with high–aspect ratio rotating bioreactors. Rat calvarial cells in gelated collagens were cultured in rotating vessels with 5 mM β-glycerophosphate–containing medium for 1, 2, or 3 wk and then analyzed for cell morphology, cell distribution, and viability, as well as for contraction of the collagen gel. The size of collagen gels with rat calvarial cells averaged 2.8 cm in diameter × 0.25 cm in thickness at the end of 3 wk. Scanning electron microscopy and laser scanning confocal microscopy of collagen gels revealed a homogenous distribution of living cells. Despite the barrier effects from induced calcification, in collagen gels, cell metabolic activity (alkaline phosphatase assay and 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide assay) increased over the 3 wk, and cell viability (trypan blue exclusion and flow cytometry analysis) remained at about 90% at the end of 3 wk. Based on our results, we determined that in situ collagen gelation provides a feasible method for engineering large dense tissue ex vivo.

Conjugated linoleic acids (CLAs) reduce fat deposition in several mammalian species. Among the proposed mechanisms for this effect are reduced preadipocyte proliferation and differentiation. We measured proliferation and differentiation of cultured human preadipocytes treated with CLAs. Preadipocytes were differentiated with insulin, hydrocortisone, transferrin, and 10% fetal bovine serum, with isobutyl-methylxanthine included for the first 2 d. The differentiation medium contained 200 μM oleic acid (C18:1), 50 μM cis-9,trans-11-CLA (9,11-CLA), or 50 μM trans-10,cis-12-CLA (10,12-CLA); the negative control medium contained no added fatty acid, and the cells did not differentiate. Cell number increased three to four times during the 17 d of differentiation, but was 30–35% lower in the CLA-treated cells than in the negative control cells. Compared with the negative control cells, differentiation was increased in the cells treated with C18:1 (increased Oil Red O–stained material [OROSM], triacylglycerol, glycerol 3-phosphate dehydrogenase activity [GPDH], peroxisome proliferator–activated receptor-γ [PPARγ] messenger ribonucleic acid [mRNA], and lipoprotein lipase [LPL] mRNA). In effect, the C18:1–treated cells act as a positive control to demonstrate the differentiation capacity of each cell lot. Both 9,11-CLA– and 10,12-CLA–treated cells had increased differentiation (increased OROSM, triacylglycerol, GPDH, PPARγ, and LPL) compared with the negative control cells. The data suggest that early in differentiation when de novo fatty acid (FA) synthesis is limited and competition for FAs by membrane and triacylglycerol synthetic pathways is great, human preadipocytes do not differentiate unless a PPARγ ligand is added. Either CLA isomer or C18:1 can provide such a ligand.

Here, we reported the effects of 17β-estradiol (E2), isoflavone genistein (Gen), and daidzein (Dai) on the production of interferon (IFN)-γ by splenocytes isolated from C57BL/6N mice. When mouse splenocytes were stimulated with lipopolysaccharide, E2, Gen, and Dai suppressed the production of IFN-γ. However, when only nonadherent cell populations of splenocytes were tested, none of these estrogenic compounds suppressed IFN-γ production. This result indicates that IFN-γ production by nonadherent cell populations of splenocytes treated with estrogens is regulated by adherent cell populations. Moreover, direct cell–cell interaction between both populations was necessary for suppression of IFN-γ production by nonadherent populations. In addition, E2 conjugated with bovine serum albumin inhibited IFN-γ production as well as E2. This result suggests that the plasma membrane–associated estrogen receptor plays a prominent role in this suppression mechanism.

Bovine pituitary extract (BPE) is routinely used as a mitogenic supplement in serum-free growth medium. In addition to its mitogenic activity, BPE contains a variety of growth factors and hormones with reported antioxidant activity. This study examines the antioxidant potential of BPE in nontumorigenic human prostate epithelial cells (RWPE-1). Treatment of RWPE-1 cells with BPE (50 μg/ml) provided significant protection against H₂O₂-induced cell death, deoxyribonucleic acid fragmentation, protein oxidation, and membrane damage. Treatment with heat (71° C, 10 min) and proteolytic enzymes reduced the antioxidant activity of BPE, suggesting that proteins present in BPE may be responsible for the antioxidant activity. Residual catalase activity present in BPE was responsible for a portion (30%) of the antioxidant activity. Interestingly, RWPE-1 cells treated with BPE and H₂O₂ rapidly accumulated intracellular reactive oxygen species (ROS) to a greater extent than cells receiving only H₂O₂. Pretreatment of RWPE-1 cells with tyrosine kinase inhibitors (genistein, tyrphostin 47, and AG-1296) before the addition of H₂O₂ diminished BPE protection against H₂O₂-induced cell death, whereas treatment with purified mitogens commonly found in BPE, growth hormone and basic fibroblast growth factor, did not protect against oxidative damage. Taken together, these data suggest that BPE contains proteins or protein complexes with remarkable antioxidant activity. These yet unidentified compounds appear to confer protection against H₂O₂-induced cell death by tyrosine kinase–dependent pathways that increase intracellular ROS generation. The antioxidant activity of BPE may represent a confounding variable when studying oxidative stress in cells maintained in BPE-supplemented serum-free medium.

Much of the research on fescue toxicosis has concentrated on evaluating animal response to grazing endophyte-infected (E ) versus endophyte-free tall fescue or the effects of single toxins such as ergonovine (EN), ergovaline (EV), or ergotamine (ET) on animal performance. Such approaches have eliminated the opportunity to test the possible additive, synergistic, or antagonistic interactions of one or more ergot alkaloids with the other ergot alkaloids found in E tall fescue. This study was conducted to determine the effects of simultaneous exposure of pairs of EN, EV, and ET on the kidney adenosine triphosphatase (ATPase) system in vitro. Tests were performed using three separate rat kidney homogenates and were repeated four times at concentrations of 0, 75, and 200 μM. Individually, EN, EV, and ET induced dose-dependent inhibitions of kidney Na /K ATPase, with EN being most potent, followed by purified EV, and then by ET. The ergot alkaloids inhibited Mg² ATPase to a lesser degree than Na /K ATPase, with EN again being the most potent toxin. Simultaneous exposure to any combination of the ergot alkaloid pairs tested (EV ET, EV EN, and ET EN) resulted in significant interactions (P < 0.05), indicating antagonistic effects on the inhibition of Na /K ATPase and Mg² ATPase for most concentration combinations. These interactions suggest that in studies of the effects of any ergot alkaloid on animal performance, effects of other ergot alkaloids may also be present. Effects may not be additive, as was the case in this study, and the presence of one toxin may enhance or hinder the effectiveness of others.