Influence of fatty acids and bovine serum albumin on the growth of human hepatoma and immortalized human kidney epithelial cells

Linoleic and oleic acids enhance cell migration by altering the dynamics of microtubules and the remodeling of the actin cytoskeleton at the leading edge

Fatty acids (FA) have a multitude of biological actions on living cells. A target of their action is cell motility, a process of critical importance during cancer cell dissemination. Here, we studied the effect of unsaturated FA on ovarian cancer cell migration in vitro and its role in regulating cytoskeleton structures that are essential for cell motility. Scratch wound assays on human ovary cancer SKOV-3 cell monolayers revealed that low doses (16 μM) of linoleic acid (LA, 18:2 ω6) and oleic acid (OA; 18:1 ω9) promoted migration, while α-linolenic acid (ALA, 18:3 ω3), showed a migration rate similar to that of the control group. Single cell tracking demonstrated that LA and OA-treated cells migrated faster and were more orientated towards the wound closure than control. In vitro addition of those FA resulted in an increased number, length and protrusion speed of filopodia and also in a prominent and dynamic lamellipodia at the cell leading edge. Using time-lapse video-microscopy and FRAP we observed an increase in both the speed and frequency of actin waves associated with more mobile actin and augmented Rac1 activity. We also observed that FA induced microtubule-organizing center (MTOC)-orientation towards the cell front and affected the dynamics of microtubules (MT) in the direction of cell migration. We propose that environmental cues such as OA and LA present in ascitic fluid, should be taken into account as key factors for the regulation of cell migration.

Albumin promotes proliferation of G1 arrested serum starved hepatocellular carcinoma cells

Albumin is the most abundant plasma protein and functions as a transport molecule that continuously interacts with various cell types. Because of these properties, albumin has been exploited by the pharmaceutical industry to improve drug delivery into target cells. The immediate effects of albumin on cells, however, require further understanding. The cell interacting properties and pharmaceutical applications of albumin incentivises continual research into the immediate effects of albumin on cells. The HepG2/C3A hepatocellular carcinoma cell line is used as a model for studying cancer pathology as well as liver biosynthesis and cellular responses to drugs. Here we investigated the direct effect of purified albumin on HepG2/C3A cell proliferation in the absence of serum, growth factors and other serum originating albumin bound molecules. We observed that the reduced cell counts in serum starved HepG2/C3A cultures were increased by the inclusion of albumin. Cell cycle analysis demonstrated that the percentage of cells in G1 phase during serum starvation was reduced from 86.4 ± 2.3% to 78.3 ± 3.2% by the inclusion of albumin whereas the percentage of cells in S phase was increased from 6.5 ± 1.5% to 14.3 ± 3.6%. A significant reduction in the cell cycle inhibitor protein, P21, accompanied the changes in the proportions of cell cycle phases upon treatment with albumin. We have also observed that the levels of dead cells determined by DNA fragmentation and membrane permeabilization caused by serum starvation (TUNEL: 16.6 ± 7.2%, ethidium bromide: 13.8 ± 4.8%) were not significantly altered by the inclusion of albumin (11.6 ± 10.2%, ethidium bromide: 16.9 ± 8.9%). Therefore, the increase in cell number was mainly caused by albumin promoting proliferation rather than protection against cell death. These primary findings demonstrate that albumin has immediate effects on HepG2/C3A hepatocellular carcinoma cells. These effects should be taken into consideration when studying the effects of albumin bound drugs or pathological ligands bound to albumin on HepG2/C3A cells.

Serum albumin and self-reported prevalence of stroke: a population-based, cross-sectional study

BACKGROUND

Since information about the association between serum albumin and risk of stroke is limited the purpose of the present paper was to re-investigate this relationship.

DESIGN

The study followed a cross-sectional design.

METHODS

In the cross-sectional Norwegian Oslo Health Study the concentration of serum albumin and blood pressure was determined in a random sample of 5071 men and women, 30-75 years of age. Logistic regression was used to study the association between the serum albumin concentration and self-reported prevalence of stroke. In the sample there were 122 subjects with a history of stroke and 4949 subjects without.

RESULTS

Low albumin (i.e. < or =47 versus >47 g/l) was associated with increased prevalence of self-reported stroke (odds ratio 1.83; 95% confidence interval, 1.20-2.78; P=0.005), after adjusting for age (< or =45 versus > or =59 years) and sex. Including smoking, blood pressure and length of education into the model did not have any major influence on the result.

CONCLUSION

Low serum albumin is associated with increased prevalence of self-reported stroke.

Serum albumin and blood pressure: a population-based, cross-sectional study

BACKGROUND AND PURPOSE

Information about the association between serum albumin and blood pressure is limited. The purpose of the present paper was to investigate this relationship in different age groups in males and females.

METHODS

In the cross-sectional Norwegian Oslo Health Study, the concentration of serum albumin and blood pressure was determined in 5071 men and women 30-75 years of age. The albumin-blood pressure relationship was studied using multiple regression.

RESULTS

In general, men had higher albumin values than women, and young subjects had higher albumin values than old. Within all age groups and in both sexes, systolic and diastolic blood pressure increased with increasing albumin concentration within the physiological range. An increase in the albumin concentration over the physiological range from approximately 40 to 50 g/l was associated with an increase in the systolic blood pressure between 5 and 11 mmHg in males, depending on age, and between 6 and 17 mmHg in females. Corresponding increases in diastolic blood pressure were between 3 and 7 mmHg in males, and 4 to 9 mmHg in females. Per one SD increment in the albumin concentration the blood pressure increase was 1-3 mmHg.

CONCLUSION

Within the different age groups, irrespective of sex and age, a positive association was found between serum albumin and blood pressure. Since albumin, in contrast to high blood pressure, is considered to be cardioprotective, the two variables probably affect cardiovascular risk by unrelated mechanisms.

Lipid peroxidation and growth inhibition of human microvascular endothelial cells

Peroxidation products of polyunsaturated fatty acids may cause growth inhibition of cells in culture. This study was carried out to elucidate to what extent peroxidation products may be found in growth media, with and without cells and albumin, using thiobarbituric acid-reactive substances (TBARS) and protein carbonyl groups as measures of peroxidation. The growth of human microvascular endothelial cells was studied as influenced by docosahexaenoic (C22:6, n - 3), arachidonic acid (C20:4. n - 6), and serum albumin. Cell growth was strongly inhibited by the fatty acids, and the inhibition was related to the concentration of TBARS in the medium. Defatted albumin (0.5 g/100 ml) nullified the increase of TBARS in the medium and released the growth inhibition by the fatty acids. With polyunsaturated fatty acids (PUFA) there was a time- and concentration-dependent increase in media TBARS, observed both with and without cells, but the TBARS increase was somewhat greater in the presence of cells. Surprisingly, TBARS in cell-free media also increased somewhat upon increasing the albumin concentration from 0.5 to 5 g/100 ml, and the TBARS increase differed among various preparations of albumin. Unexpectedly, the albumin that had not been defatted gave the lowest TBARS values. The amount of protein carbonyl groups did not differ among various albumin preparations. It is concluded that PUFA may autooxidize in media used for cell cultures, and thereby cause an unspecific growth inhibition, which can be prevented by a low albumin concentration. However, even defatted albumin preparations may contain lipid peroxidation products, the causes and implications of which remain to be elucidated.

Cell cycle arrest and induction of apoptosis in pancreatic cancer cells exposed to eicosapentaenoic acid in vitro

Eicosapentaenoic acid (EPA) has been shown to have an inhibitory effect on the growth of several pancreatic cancer cell lines in vitro. This study investigates the mechanism of growth inhibition and cytotoxicity of EPA on the pancreatic cancer cell line MIA PaCa-2. Cells were analysed for cell count, viability, cell cycle distribution and ultrastructural changes. There was a time- and dose-dependent decrease in cell count and viability in cultures of pancreatic cancer cells supplemented with EPA. Flow cytometric DNA analysis of MIA PaCa-2 cells incubated with EPA demonstrated the presence of sub G1 populations corresponding to the presence of apoptotic cells and the blockade of cell cycle progression in S-phase and G2/M-phase. The presence of apoptosis in EPA-supplemented cultures was further confirmed by DNA fragmentation and ultrastructural changes associated with apoptosis. Therefore, we conclude that EPA mediates its effect on the pancreatic cancer cell line MIA PaCa-2, at least in part, via cell cycle arrest and the induction of apoptosis.

Blood reticulocyte count and plasma lactate dehydrogenase activity are positively related to the free fatty acid/albumin ratio in geriatric patients

The objective of this study was to investigate the in vivo relationship between plasma free fatty acid (FFA)/albumin molar ratio and indicators of cellular damage. A case series study was carried out in 20 geriatric patients in a stable clinical condition. Their plasma albumin concentration was in the range 26-42 g l-1. There was a significant positive correlation between the FFA/albumin ratio and (a) reticulocyte count (r = 0.61, p = 0.006), (b) lactate dehydrogenase activity (r = 0.69, p = 0.002), and (c) haptoglobin concentration (r = 0.46, p = 0.05). The haemoglobin concentration was inversely related to relative reticulocyte count (r = -0.55, p = 0.01). Absolute and relative reticulocyte counts were positively associated (r = 0.92, p < 0.0001). The results are in accordance with the contention that a high FFA/albumin ratio in vivo may elicit cellular damage. Further studies are required to elucidate to what extent a high FFA/albumin ratio might be causally related to diseases.

Effects of various fatty acids alone or combined with vitamin E on cell growth and fibrinogen concentration in the medium of HepG2 cells

Dietary intake of fish oils, rich in the polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has given inconsistent results as to their influence on the plasma fibrinogen level (1, 2, 3, 4, 5, 6). In the present study we have examined the effects of various fatty acids, the PUFAs and the saturated fatty acid palmitic acid (PA), alone or combined with the antioxidant vitamin E (Vit.E), on the fibrinogen concentration in the growth medium of human hepatoma (HepG2) cells. Vit.E alone decreased the amount of fibrinogen in the medium in a dose dependent fashion, where fibrinogen was measured as Fibrinopeptide A (FPA) releasable by thrombin. EPA and Vit.E decreased the amount of fibrinogen additively. PUFAs alone increased the fibrinogen concentration in a dose dependent manner. PUFAs combined with a fixed dose of Vit.E decreased the fibrinogen concentration, also dose dependently. OA and PA had an inhibitory effect, both alone and combined with Vit.E. These results indicate that Vit.E may be necessary for PUFAs to have a fibrinogen lowering effect, whereas both OA and PA apparently may decrease the fibrinogen concentration in the cell medium of HepG2 cells, both alone and combined with Vit.E. Possibly, peroxidation of the PUFAs may increase the fibrinogen production, that may be counteracted and reversed by the simultaneous presence of Vit.E.

Dietary fish oils and long-term malaria protection in mice

Previous studies indicate a suppressive influence of fish oils on rodent malaria. The present work was carried out to study (i) the dose-effect relation between dietary fish oils and lethality of primary malaria infection in mice; (ii) the modifying influence of vitamin E; and (iii) the effect of previous fish oil feeding on parasitemia and lethality of a rechallenge infection. For two or four weeks, groups of weanling male mice were fed a standard laboratory diet or one of eight purified diets containing various amounts of fish oil (providing 6-21% of energy). The diets were prepared with and without vitamin E. After the two- or four-week feeding period, the mice were injected intraperitoneally with Plasmodium yoelii-infected erythrocytes. Six months after the primary infection (four months after discontinuing fish oil feeding), the surviving mice were again injected intraperitoneally with parasitized red blood cells (or even better--erythrocytes, erythrocytes are used elsewhere). Primary malaria infection was lethal in mice fed standard diet alone or with fish oil and vitamin E added. In contrast, feeding a fish oil-based diet without vitamin E improved survival to at least 70% if the mice had been fed these diets for four weeks. Protection against malaria did not seem to be related to the fish oil dose used. Regardless of the previous fish oil dose, all the mice surviving the primary infection survived the rechallenge infection with low parasitaemias.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of n-3 fatty acids during neoplastic progression and comparison of in vitro and in vivo sensitivity of two human tumour cell lines

Several studies have shown that dietary lipid exerts an effect on carcinogenesis. We report here that progression to malignancy in vitro is associated with changes in the response to fatty acids (FAs). Tumorigenic (THKE) cells were more sensitive to the n-3 FAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than immortalised (IHKE) cells. The growth of THKE cells was inhibited 25% more than the growth of IHKE cells at 80 microM EPA (P < 0.01) and 35% more at 40 microM DHA (P < 0.001). Furthermore, the results indicate that there is a wide cell type variation in the response to FAs. We found that the in vitro inhibition by FAs correlated with the reduction in the growth rate of the tumour in nude mice fed K85 (55% EPA and 30% DHA). A significant difference in tumour latency was observed for the A427 cell tumour groups (10 days, P < 0.05). Tumours in the animals fed n-3 FA exhibited significantly higher levels of EPA and DHA; the level of arachidonic acid (ARA) was significantly lower in THKE tumours and the level of linoleic acid (LA) was significantly lower in A427 tumours than in controls fed corn oil. The higher sensitivity of the A427 cell line was not explained by higher uptake of EPA/DHA.