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Biomedical subjects

A Estival

Publications and source records attributed to A Estival.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of two types of inocula during acclimation and stable operation for nitrophenol biodegradation in an anaerobic-aerobic SBR.

This work presents a comparison of two inocula used for the acclimation of two anaerobic-aerobic sequencing batch bioreactors used for toxic wastewater treatment. The bioreactors were acclimated with different types of sludge: one coming from an anaerobic wastewater treatment plant and the other one from a conventional aerobic activated sludge plant. The model toxic compound was p-nitrophenol, which is reduced to p-aminophenol during the initial anaerobic phase of the reaction, and later mineralized during a posterior aerated reaction phase. Biodegradation of the compounds was monitored using UV/Vis spectrophotometry. After acclimation stabilization of the sludge and of the process was also monitored. Results show that there is no significant difference in acclimation times and stability of the process between the two employed inocula, and thus an originally anaerobic inoculum presents no apparent advantage over a more easily accessible aerobic one.

Aerobiosis↗
PubMed2001

Expression of the high molecular weight fibroblast growth factor-2 isoform of 210 amino acids is associated with modulation of protein kinases C delta and epsilon and ERK activation.

The high molecular weight (HMW) fibroblast growth factor (FGF)-2 isoform of 210 amino acids initiated at a CUG start codon possesses a nuclear localization sequence and is not secreted. In contrast, the low molecular weight (LMW) isoform of 155 amino acids initiated at the AUG start codon can be secreted and activates the cell surface FGF receptors. The two isoforms possess different biological properties; however, little is known about the intracrine regulatory mechanisms involved in the biological effects of the HMW FGF-2 isoform. Using pancreatic cells stably transfected with cDNAs leading to the expression of either the HMW FGF-2 (A3 cells) or the LMW form (A5 cells), we provide evidence that the two FGF-2 isoforms differentially modulate PKC levels. The LMW FGF-2 up-regulated the PKC epsilon levels by 1.6-fold; by contrast the HMW isoform down-regulated the level of this PKC isotype by about 3-fold and increased the amount of PKC delta by 1.7-fold. PKC mRNAs were also modified, suggesting that PKC expression was regulated at a pretranslational level. Additionally, expression of different levels of the HMW FGF-2 with an inducible expression system confirmed the role of this isoform on PKC delta and epsilon expressions. Increased activation of ERK-1 and -2 was also observed in cells expressing the HMW FGF-2. By using different PKC inhibitors and a dominant negative PKC delta, it was found that ERK activation was PKC delta-dependent. These data indicate that expression of HMW FGF-2 can modify PKC levels by acting at the intracellular level and that the overexpression of PKC delta induces ERK-1/2 activation. The expression of a dominant negative FGFR1 did not reduce ERK-1/2 activation by the HMW FGF-2, suggesting that ERK activation does not require FGFR activity. The signaling cascade downstream of ERK might be involved in the known mitogenic effect exerted by this FGF-2 isoform.

Animals↗
PubMed2000

FGF-2 isoforms of 18 and 22.5 kDa differentially modulate t-PA and PAI-1 expressions on the pancreatic carcinoma cells AR4-2J: consequences on cell spreading and invasion.

Pancreatic tumors overexpress FGF-2 and t-PA, but the implication of the growth factor in t-PA synthesis and t-PA-dependent tumor invasion remains unknown. FGF-2 is present in different isoforms: The 18 kDa FGF-2 is secreted, while the 22.5 kDa one is nuclearized and exerts intracrine regulations bypassing cell-surface FGF receptors. Rat pancreatic carcinoma AR4-2J cells producing either the 18 or the 22.5 kDa FGF-2 after transfection with FGF-2 cDNAs have been used to analyze the role of FGF-2 in t-PA expression and t-PA-related cell spreading. The 22.5 kDa FGF-2 reduced t-PA and PAI-1 synthesis 2-fold. Addition of recombinant 18 kDa FGF-2 (rFGF-2) to cell cultures resulted in increased t-PA and decreased PAI-1 expression. By contrast, rFGF-2 did not significantly modify t-PA synthesis in cells producing the 22.5 kDa FGF-2. Cell spreading was t-PA-dependent. Furthermore, cells producing the 22.5 kDa FGF-2 migrated less than control cells and cells producing the 18 kDa FGF-2. Overall, our data show that secretory FGF-2 is involved in t-PA synthesis by pancreatic cancer cells and facilitates cell spreading. The 22.5 kDa FGF-2 exerts opposite effects by decreasing t-PA expression in basal conditions and during rFGF-2 stimulation. Since the expression of the 22.5 kDa FGF-2 is under specific controls, its up-regulation might have the potential to reduce spreading of pancreatic cancer cells.

Animals↗
PubMed1999

The CCKB/gastrin receptor is coupled to the regulation of enzyme secretion, protein synthesis and p70 S6 kinase activity in acinar cells from ElasCCKB transgenic mice.

In order to determine which physiological functions can be regulated by the pancreatic CCKB/gastrin receptor, studies were carried out on pancreatic acini from mice expressing transgenic CCKB/gastrin receptors in the exocrine pancreas (ElasCCKB mice). Acini were stimulated by sulfated gastrin in the presence of SR 27897 (1.8 microM), blocking endogenous CCKA receptors. After 30 min incubation with gastrin, the secretion of chymotrypsinogen and amylase showed superimposable monophasic dose-response curves. Enzyme secretion was detectable and maximal at 100 pM and 1 nM of gastrin, respectively. No increase in chymotrypsinogen and amylase mRNAs was detected for doses of gastrin which specifically occupy the CCKB/gastrin receptor. In contrast, gastrin stimulated total protein synthesis in isolated acini from ElasCCKB mice. [35S]Methionine incorporation into total proteins was increased dose-dependently to a maximum for 30 pM gastrin and inhibited with higher doses (> 300 pM). Gastrin stimulated p70 S6 kinase activity for concentrations ranging from 10 pM to 1 nM. Gastrin-stimulated p70 S6 kinase activity and protein synthesis were blocked by rapamycin and wortmannin. Therefore, in ElasCCKB mice acinar cells, the CCKB/gastrin receptor mediates enzyme release and protein synthesis. However, a more efficient coupling of the CCKB/gastrin receptor to protein synthesis than to enzyme secretion was demonstrated. CCKB/gastrin receptor-stimulated protein synthesis likely results from an enhancement of mRNA translation and involves phosphatidyl inositol 3-kinase and p70 S6 kinase.

Amino Acid Sequence↗
PubMed1997

Pancreatic cancer cell regulation by lipids and by basic fibroblast growth factor expression.

High fat intake is a risk factor for pancreatic cancer. Lipids may act either directly or in cooperation with growth-promoting polypeptides. In this study, the role of serum lipids, and mainly the often expressed intracellular basic fibroblast growth factor (bFGF) isoforms in cancer cells, was analyzed in pancreatic tumor cell proliferation. Serum lipids alone induced a 1.9-fold increase of human pancreatic cancer cell growth (p < 0.001). Treatment with bFGF had a weak mitogenic effect (1.2- to 1.3-fold increase) compared with those of insulin and transferrin (1.7- to 1.6-fold increase, respectively). The bFGF expression by a rat pancreatic cancer cell line that was transfected with bFGF cDNAs modified cell lipid contents and induced a higher proliferation rate than that found with the exogenous bFGF. Combined extra- and intracellular bFGFs increased cell growth by two to three times (p < 0.001), regardless the presence of extracellular lipids. The results obtained reflect the direct mitogenic effect of serum lipids and suggest that the endogenous bFGF of high molecular weight may be implicated in pancreatic cancer cell growth. By modifying cell lipids, bFGFs may interfere with other cell functions, like signal transduction.

Animals↗
PubMed1996

Cells retrovirally transfected with fibroblast growth factor-2 isoforms exhibit altered adenylate cyclase activity and G-protein functionality.

Basic fibroblast growth factor (FGF-2) is synthesized as different molecular mass isoforms all lacking the signal-peptide sequence. The high molecular-mass isoforms (21-24 kDa) possess a signal sequence directing their nuclear translocation. The role of each isoform is still poorly understood, however, modifications in intracellular signalling pathways could explain some effects of these peptides. In order to evaluate the role of FGF-2 isoforms on the adenylate cyclase (AC) signalling pathway, we retrovirally infected a rat pancreatic cell line (AR4-2J) with point-mutated FGF-2 cDNAs, allowing the expression of the 18 (A5 cells) or 22.5 kDa isoform (A3 cells) at a low level. In membrane preparations of A3 cells, unscheduled expression of the 22.5 kDa FGF-2 isoform induced a 2-fold decrease in both basal and forskolin-stimulated AC activity. Studies carried out on intact cells also showed decreased accumulation of cAMP in A3 cells in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Both FGF-2 peptides also induced functional modifications of G-proteins without affecting their levels. The 22.5 kDa peptide led to enhanced ADP-ribosylation of both alpha(s)-subunits in vitro, whereas the expression of the low molecular-mass 18 kDa peptide resulted in a 2-fold increase in alpha12 and alpha0 ADP-ribosylations. Furthermore, control CAT cells (AR4-2J cells transfected with the retrovirus containing the chloramphenicol acetyltransferase gene) and A5 cells were growth-inhibited by 8-Br-cAMP, in contrast to A3 cells. These data provide evidence that the expression of FGF-2 peptides could play a role in cell functions by modifying the AC signalling pathway. FGF-2 peptides are able to modulate both AC activity and the regulatory G-proteins. Finally FGF-2 expression may interfere with cAMP-regulated cell proliferation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Differential regulation of fibroblast growth factor (FGF) receptor-1 mRNA and protein by two molecular forms of basic FGF. Modulation of FGFR-1 mRNA stability.

To evaluate possible functional differences between basic fibroblast growth factor (FGF) 2 isoforms we analyzed the effects of the 18-kDa FGF-2 which mainly localizes in the cytosol and that of the nuclear-targeted 22.5-kDa form on FGF receptors (FGFR) expression. These peptides were expressed at low amounts through a retroviral-infection system. Point mutated FGF-2 cDNAs under the control of the beta-actin promoter were used to infect a pancreatic cell line (AR4 2J) which does not produce FGF-2. Saturation and competition binding studies with 125I-FGF-2 revealed a 3-fold increase in both high and low affinity receptors in cells expressing the 22.5-kDa form and a 2-fold increase only in the high affinity receptors in cells producing the 18-kDa form. Kd values and molecular weights of the high affinity receptors were unaffected. Increasing cell densities or cell treatment with exogenous FGF-2 resulted in FGFR down-regulation as in control cells. Neutralizing anti-FGF-2 antibodies and suramin did not affect receptor density in control and in cells producing the 22.5-kDa form but further increased by 60 and 80%, respectively, the receptor level in cells synthesizing the 18-kDa form. These data suggest the involvement of the intracellular stored FGF-2 in FGFR up-regulation. Although all cells expressed FGFR-1, -2, and -3 mRNA only the FGFR-1 transcript was found increased, 6-fold in 22.5-kDa expressing cells and 3-fold in cell producing the shortest secreted isoform. The increase in FGFR-1 mRNA levels in the 22.5-kDa expressing cells was due to enhanced stability of the transcript. Confocal microscopy detected the presence of FGFR-1 at the cell surface whereas secretory isoforms of the receptor were not observed. Reverse transcriptase-polymerase chain reaction did not reveal significant differences in the expression of FGFR-1 variants. In the 22.5-kDa expressing cells exogenous FGF-2 evoked a stronger translocation of the calcium-phospholipid-dependent PKC. These results indicate that the transfected FGF-2 isoforms up-regulated FGFR-1 mRNA and protein. The 22.5-kDa form acted by increasing FGFR-1 mRNA stability enhancing cell responses to exogenous FGF-2.

Animals↗
PubMed1996

Evidence for specific involvement of 5-HT1A and 5-HT2A/C receptors in the expression of patterns of spontaneous motor activity of the rat.

The 5-HT1A and the 5-HT2A/C receptor agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (0.006-0.4 mg kg-1 s.c.) and (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (0.05-4.0 mg kg-1 s.c.), respectively, produced a similar stereotyped forward locomotion in rats, although the intensity of the behavioral change was considerably less with DOI. The stereotyped forward locomotion was accompanied by a slight decrease in total activity, suppression of rearing behavior and an increased activity in the periphery of the open-field arena. In support of receptor specificity, the effects of 8-OH-DPAT and DOI could be antagonised by pretreatment with the 5-HT1A/B and the 5-HT2A/C receptor antagonists (-)-pindolol (2 mg kg-1 s.c.) and ritanserin (2 mg kg-1 s.c.), respectively. In addition, (-)-pindolol, but not the selective beta-adrenoceptor antagonist betaxolol, markedly enhanced the behavioral effects produced by DOI. The nature of these specific actions and interactions in terms of pre- and post-synaptic serotonergic mechanisms remains an important question.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

Expression of two FGF-2 isoforms in pancreatic acinar cells (AR4-2J). Intracellular localization and role in the regulation of the extracellular matrix biosynthesis.

Fibroblast growth factor (FGF-2) is a multifunctional growth factor. In cells producing this factor, FGF-2 is synthesized as different molecular weight isoforms lacking the signal peptide sequence for secretion. All forms are highly concentrated in cells. The presence of a nuclearization signal sequence in some isoforms suggests the involvement of these isoforms in cell functions bypassing the cell surface receptors. Our aims were to better define the intracellular localizations of the FGF-2 isoforms by immunocytochemistry and confocal microscopy and to analyze whether these isoforms were involved in the expression of extracellular matrix (ECM) components. We chose the pancreatic acinar cell line AR4-2J since it does not synthesize FGF-2. These cells were retrovirally transfected by point-mutated FGF-2 cDNAs. The cell lines obtained produced either the 18 kDa form (A5 cells) or the 22.5 kDa form (A3 cells). In A5 cells, the 18 kDa form was found in the cytoplasm, on the cell surface reflecting its secretion, and in the nucleoli. Parental AR4-2J cells treated with exogenous FGF-2 exhibited identical localizations, suggesting that in A5 cells the 18 kDa form followed the same translocation pathways than the exogenous FGF-2. By contrast, in A3 cells the 22.5 kDa form was predominantly localized in the nucleoplasm but was undetectable on the cell surface, suggesting its direct translocation to the nucleus. Northern and Western blot analysis showed that cells expressing the high molecular weight form exhibited a decrease of laminin B1 protein level and mRNA stability. In contrast, collagen IV and fibronectin expressions were unmodified either in FGF-2-transfected cells or in parental cells treated by exogenous FGF-2. Thus, these data indicate that: 1) 18 and 22.5 kDa FGF-2 are preferentially localized in different nuclear compartments and 2) the high molecular weight form plays a role on the expression of some ECM components.

Animals↗
PubMed1993

Morphological and biological modifications induced in a rat pancreatic acinar cancer cell line (AR4-2J) by unscheduled expression of basic fibroblast growth factors.

The role of the different basic fibroblast growth factor (bFGF) forms on the regulation of pancreatic acinar cancer cells was analyzed on the rat cell line AR4-2J. This cell line expresses bFGF receptors but does not produce bFGF. AR4-2J cells were retrovirally transfected with the wild type or with point-mutated bFGF complementary DNAs in order to obtain the expression of all the bFGF forms (clone A4), or of that of the M(r) 22,500 form (clone A3), or of that of the M(r) 18,000 form (clone A5). Each clone was less tumorigenic in nude mice than AR4-2J cells. In culture, only the coexpression of all the bFGF forms modified cell morphology (fibroblast-like) and secretory enzyme synthesis (about a 20-fold decrease of amylase and lipase). Cells expressing the high molecular weight bFGF (A3 and A4) were able to grow in serum-free medium. As for AR4-2J, exogenously added bFGF still exerted mitogenic effects on the bFGF-producing cells. These results suggest that pancreatic acinar cancer cells may respond to endogenous bFGF; furthermore, they seem very sensitive to the coexpression of the different bFGF forms which is often described in cancer cells.

Amylases↗
PubMed1993

Caerulein and gastrin(2-17 ds) regulate differently synthesis of secretory enzymes, mRNA levels and cell proliferation in pancreatic acinar cells (AR4-2J).

In order to characterize the biological functions coupled to cholecystokinin (CCK) A and B receptors, the effects of gastrin(2-17 ds) and caerulein were compared. An isolated cell model, the pancreatic acinar cell line AR4-2J, was used and the experiments were carried out in serum-free media. Caerulein was found to evoke no mitogenic effects either alone or in the presence of the CCK antagonists L364,718 and CR1409. Gastrin(2-17 ds) increased cell proliferation by 2-fold with an IC50 of 150 pM, corresponding to the occupancy of the CCK B receptors. CR1409, at concentrations that fully occupied CCK B receptors, inhibited the gastrin(2-17 ds) effects. Caerulein enhanced chymotrypsinogen biosynthesis by 100% and the corresponding mRNA level by 75%; amylase biosynthesis and mRNA level were enhanced by 40% only. Half-maximal increases in chymotrypsin activity and mRNA level were recorded in response to caerulein at concentrations of 100 pM and 50 pM respectively. Gastrin(2-17 ds) at 100 nM enhanced chymotrypsinogen biosynthesis by 26% and its mRNA level by 35%; these responses were lower than those evoked by 0.1 nM caerulein. Furthermore, CR1409 completely inhibited caerulein- and gastrin(2-17 ds)-stimulated chymotrypsinogen synthesis, with similar IC50 (4 microM). These results suggest that both peptides induced the synthesis of the secretory enzyme after occupancy of CCK A receptors.

Amylases↗
PubMed1992

Decreased expression of transforming growth factor alpha during differentiation of human pancreatic cancer cells.

The relationship between cell differentiation and transforming growth factor alpha (TGF-alpha) expression in human pancreatic cancer cells was analyzed in Capan 1 cells. These cells differentiate either spontaneously or after butyrate treatment. During differentiation (spontaneous or butyrate induced), TGF-alpha messenger RNA (mRNA) levels decreased, whereas the TGF-beta 1 mRNA levels remained unchanged. TGF-alpha was present in cells as proTGF-alpha, which decreased after butyrate treatment. Secretion of TGF-alpha was not found. Under the two conditions of differentiation, the membrane-bound protein kinase C activity was also reduced. Conversely, long-term phorbol ester treatment increased both membrane-bound protein kinase C activity (260%) and TGF-alpha mRNA level (500%), a not significant increase of TGF-beta 1 mRNA was observed. However, phorbol 12-myristate-13-acetate did not induce TGF-alpha synthesis or secretion. These data suggest that expression of TGF-alpha can be reduced in cancer cells; they also suggest the existence of a relationship between TGF-alpha expression and cell differentiation. In addition, the protein kinase C-induced TGF-alpha mRNA level was not followed by the increase of TGF-alpha biosynthesis, suggesting a translational control. Finally, the expression of TGF-alpha and -beta 1 messengers appears to be differently regulated.

Butyrates↗
PubMed1992

[Transfection of pancreatic acinar cells (AR4-2J) by bFGF modifies cell morphology and biosynthesis of pancreatic secretory enzymes].

Basic fibroblast growth factor (bFGF or FGF-2) is present in the basal membrane of pancreatic cells during the pancreatic embryonic development. The expression of bFGF receptors has been described in normal pancreatic cells. By contrast, pancreatic cancer cells express not only the bFGF receptors but also the bFGF itself. With the aim of understanding the effects induced by the production of bFGF by pancreatic cancer cells, the pancreatic acinar cell line (AR4-2J) was used. AR4-2J cells do not produce bFGF but express bFGF receptors. These cells were transfected with a vector containing the bFGF cDNA encoding the three different forms of bFGF characterized in tumor cells. Results showed that the bFGF expression induced important phenotypic and enzymatic modifications. The transfected cells lost some morphological features of the acinar cells and expressed amylase and lipase at low levels (a 90% decrease for amylase activity, whereas lipase activity was barely detectable). These results suggest that bFGF could be involved in maintaining pancreatic cells in a slightly differentiated state.

Amylases↗
PubMed1991

Oxyntomodulin and related peptides control somatostatin secretion in RIN T3 cells.

We studied the effects of oxyntomodulin (OXM), of its C-terminal (19-37) fragment (OXM (19-37)) and of glucagon (GLU) on somatostatin release, cyclic AMP accumulation and inositol phosphate turnover in somatostatin-secreting RIN T3 cells in culture. Rapid changes in cellular free Ca2+ were also measured using fura-2. Carbachol was used as a control test agent for the parameters involving the inositol phosphate/Ca2+ cascade. OXM, GLU and OXM (19-37) were all able to stimulate somatostatin release with relative ED50 of approx. 1, 22 and 45, respectively. OXM and GLU stimulated cyclic AMP levels with relative ED50 of approx. 1 and 30, respectively, whereas OXM (19-37) was totally ineffective on this parameter. In contrast to carbachol, none of the peptides significantly modified the inositol phosphate turnover or induced rapid changes in cellular free Ca2+. We conclude that the RIN T3 cells contain a receptor-cyclic AMP system similar to that found in gastric mucosa and that this system is linked to somatostatin release. Another receptor-second messenger mechanism linked to somatostatin release is triggered by the (19-37) fragment. This mechanism is not the inositol phosphate/Ca2+ cascade triggered in the same cells by cholinergic agents.

Animals↗
PubMed1991

Regulation of amylase and chymotrypsinogen expression by dexamethasone and caerulein in serum-free-cultured pancreatic acinar AR4-2J cells. Influence of glucose.

The direct effects of dexamethasone and caerulein on two pancreatic enzymes, amylase and chymotrypsin, were determined in AR4-2J cells cultured under serum-free conditions at two glucose concentrations (1.0 and 4.5 g/l). In the absence of any hormone, the higher glucose concentration resulted in a 1.6-1.8-fold increase in the basal levels of amylase and chymotrypsinogen. Dexamethasone (50 nM) increased the biosynthesis and mRNA levels of both enzymes at both glucose concentrations. However, dexamethasone had a more pronounced effect on amylase biosynthesis (5-fold induction) than on chymotrypsinogen biosynthesis (1.8-fold induction). The parallel increases in mRNA and protein indicated the existence of pre-translational regulation. This is in contrast with what was observed in serum-containing media, where a translational regulation of amylase biosynthesis took place, probably under the control of both glucose and some serum factors. By contrast, caerulein (10 nM) exerted a more specific action on chymotrypsinogen. The increases in chymotrypsinogen mRNA were 2.2- and 2.1-fold, and increases in chymotrypsin activity were 1.6- and 2.9-fold at 1.0 and 4.5 g of glucose/litre respectively. Thus the regulation by caerulein occurred mainly through the enhancement of chymotrypsinogen transcription and/or mRNA stabilization.

Amylases↗
PubMed1991

Lipid-dependent proliferation of pancreatic cancer cell lines.

Capan 1, a human pancreatic cancer cell line, is routinely grown in 10% fetal calf serum (FCS). In order to characterize the factors needed for its proliferation, FCS was replaced by a synthetic serum (Ultroser G). For Capan 1 proliferation we found that Ultroser G was as efficient as FCS. A subfraction of Ultroser G containing insulin, transferrin, and lipids was found to be responsible for that response since a combination of these compounds reproduced the growth observed with 10% FCS. Lipids stimulated cell proliferation even in the absence of other factors. Other human (MIA PaCa 2, AsPC1, Panc 1) or rat (AR4-2J) pancreatic cancer cell lines tested proliferated in the reconstituted medium containing insulin (100 ng/ml), transferrin (100 micrograms/ml), fatty acid-free albumin (1 mg/ml), and bovine serum lipids (0.7%), as in 10% FCS. Furthermore, the growth of nonpancreatic cell lines (HT29, A431, CREF) was not enhanced by lipids. Lipoproteins were found to be involved in the mitogenic response of pancreatic cells to lipids, whereas phosphatidylcholine and fatty acids were either inefficient or inhibitors (MIA PaCa2 and AR4-2J). Alkaline phosphatase and amylase content, differentiation markers for Capan 1 and AR4-2J cells, respectively, were not modified by the reconstituted medium. These data suggest that lipids, insulin, and transferrin are the essential factors for the proliferation of pancreatic cancer cell lines, reproducing the growth effect of 10% FCS. Moreover, in the absence of most of the seric growth factors, pancreatic cells remained differentiated.

Blood Substitutes↗
PubMed1990

Two subclasses of EGF receptors in the human pancreatic cancer cell lines CAPAN-1 and MIA PaCa-2.

The existence of different classes of EGF receptors in human pancreatic cancer cells has yet not been determined. EGF binding to two cancer cell lines (CAPAN-1 and MIA PaCa-2) was studied. Two classes of EGF binding sites were characterized. The first class of EGF binding sites demonstrated a high affinity and low capacity for EGF, with a Kd of 0.25 +/- 0.11 nM, close to the concentration of EGF suggested to be present in human pancreatic juice. The second class of EGF binding sites had a lower affinity and a higher capacity for EGF, with Kd of 1.78 +/- 0.61 nM. The total number of EGF binding sites was about 40,000/cell. Treatment of the cells with a phorbol ester, TPA, caused a complete loss of the high affinity binding sites and also caused a decrease in the concentration of the lower affinity binding sites present on the cells. Interestingly, with the increasing age of the cells, the concentration of both the high and low affinity EGF binding sites was significantly decreased. In the presence or absence of fetal calf serum, EGF, at concentrations higher than 1.10(-10)M, exerted a dose-dependent mitogenic effect on the growth of the pancreatic cancer cells in culture. These data demonstrate the existence of two classes of binding sites for EGF on some human pancreatic cancer cells and a possible role of EGF in the growth of pancreatic tumors.

Cell Division↗