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PubMed1993

Adriamycin conjugates of human transferrin bind transferrin receptors and kill K562 and HL60 cells.

Adriamycin (ADR) was coupled to human transferrin (TRF) by using a glutaraldehyde crosslinking method. The TRF-ADR conjugates were separated by column chromatography and the molar ratio of ADR to TRF (i.e., conjugation number) for the studied conjugates was found to be 1.2. Analysis in sodium dodecyl sulfate-polyacrylamide gels demonstrated that TRF-ADR conjugates with this molar ratio had the same mobility as native TRF and contained few aggregates. The ADR remained conjugated to TRF under conditions of decreased pH known to occur in many intracellular compartments, and analysis by spectrofluorometry revealed that the conjugated ADR retained its ability to intercalate DNA. The TRF-ADR conjugates were shown by flow cytometry to preferentially bind tumor cells and cell-bound conjugates were found to be laterally mobile within plasma membranes. The binding of TRF-ADR conjugates was determined to be saturable, and competition experiments done with both radioiodinated and fluorescein-labeled TRF-ADR conjugates demonstrated dose-dependent inhibition of conjugate binding by unlabeled TRF, indicating that TRF-ADR conjugates were bound by TRF receptors. Cytotoxicity studies performed with tritiated thymidine incorporation and tetrazolium reduction assays revealed that TRF-ADR conjugates inhibited the proliferation of both K562 and HL60 cells in culture more effectively than free ADR. Such conjugates could provide a delivery system for ADR that would target the drug and possibly diminish its dose-associated complications.

Cell Survival↗
PubMed1989

The development of the transferrin-transferrin receptor system in relation to astrocytes, MBP and galactocerebroside in normal and myelin-deficient rat optic nerves.

The factor(s) which control the onset of myelination are unknown. It is now accepted that transferrin (Tf), the major iron transport protein in vertebrates, is found in oligodendrocytes in the adult brain. Because of the importance of iron in basic cell metabolism we have hypothesized that iron (mobilized by Tf) may be a permissive agent in the process of myelination. The present study was designed to determine with immunohistochemistry the relationship of Tf receptor expression, Tf accumulation, and the expression of myelin components myelin basic protein (MBP) and galactocerebroside (GAlC)) in the developing rat optic nerve. In addition to Tf and its receptor, the developmental pattern for GalC reported in this study has not been examined in the rat optic nerve. Furthermore, a myelin mutant strain of rats was used to determine if a lack of myelin production affects the Tf-Tf receptor system. Our study found that Tf receptor was expressed from birth on blood vessels and was first seen in the parenchyma of the nerve at 8 days of age. The expression of the Tf receptor preceded that of Tf, MBP or GalC. The accumulation of Tf by oligodendrocytes occurred about the same time as the intracellular appearance of MBP and GalC which was shortly after the onset of myelination. Tf-positive cells as well as MBP- and GalC-positive cells increased in number and staining intensity with age whereas the expression of the Tf receptor declined after reaching a peak at 15 days of age. In the optic nerves of myelin-deficient rats, the Tf receptor expression and Tf accumulation was confined to the vasculature. The results of this study suggest that the expression of the Tf receptor is an early event in oligodendrocytic maturation and is followed by the intracellular accumulation of myelin components and Tf. The temporal association of Tf and myelin production suggests that further study is warranted regarding the possibility that the Tf-iron system supports or perhaps even permits the initiation of the process of myelination.

Aging↗
PubMed2003

Tumour necrosis factor-alpha transcription in transferrin-stimulated human blood mononuclear cells: is transferrin receptor involved in the signalling mechanism?

Transferrin (Tf) and tumour necrosis factor-alpha (TNF-alpha) participate in immune response regulation. We studied the capacity of Tf to modulate 'in vitro' TNF-alpha secretion, membrane expression and transcription by human blood mononuclear cells (BMNC). Women 25-45 years of age with normal iron status (n = 20) or with iron deficiency (ID, n = 20) due to gynaecological bleeding were studied. BMNC were incubated with different proportions of Fe-exempt and Fe-saturated Tf (apo-Tf:holo-Tf). Apo-Tf or holo-Tf uniformly induced TNF-alpha secretion in the cell supernatants from both groups. Nevertheless, cytokine levels were significantly lower in ID subjects. For all Tf-Fe saturations assayed, mean TNF-alpha levels varied between 1.4-1.6 ng/ml and 0.4-0.7 ng/ml for normal and ID women respectively (P < 0.001). The addition of apo-Tf enhanced TNF-alpha secretion in a dose-dependent manner, but the cytokine levels were lower in ID group. Tf did not induce pro-TNF-alpha expression in monocytes and lymphocytes from either group. Tf-treated cells from normal individuals expressed approximately two to three times more TNF-alpha mRNA than cells from ID subjects. Mean values ranged 96-110 atmol/ml in normal women and 24-31 atmol/ml in ID women for all Tf-Fe saturation levels tested (P < 0.001). These results show that Tf-induced TNF-alpha secretion is transcriptionally regulated. The impaired TNF-alpha transcription in cells from ID subjects indicates that the quality of the immune response is linked to the Fe status of mononuclear cells.

Adult↗
PubMed1987

Functional expression of the human transferrin receptor cDNA in Chinese hamster ovary cells deficient in endogenous transferrin receptor.

Transferrin (Tf) receptor-variant Chinese hamster ovary cells have been isolated by selection for resistance to two Tf-toxin conjugates. The hybrid toxins contain Tf covalently linked to ricin A chain or a genetically engineered diphtheria toxin fragment. The Tf-receptor-variant (TRV) cells do not have detectable cell-surface Tf receptor; they do not bind fluorescein-Tf or 125I-Tf. TRV cells are at least 100-fold more resistant to the Tf-diphtheria toxin conjugate than are the parent cells. The TRV cells have retained sensitivity to native diphtheria toxin, indicating that the increased resistance to the conjugate is correlated with the loss of Tf binding. The endocytosis of fluorescein-labeled alpha 2-macroglobulin is normal in TRV cells, demonstrating that the defect does not pleiotropically affect endocytosis. Since these cells lack endogenous Tf receptor activity, they are ideally suited for studies of the functional expression of normal or altered Tf receptors introduced into the cells by cDNA transfection. One advantage of this system is that Tf binding and uptake can be used to monitor the behavior of the transfected receptor. A cDNA clone of the human Tf receptor has been transfected into TRV cells. In the stably expressing transfectants, the behavior of the human receptor is very similar to that of the endogenous Chinese hamster ovary cell Tf receptor. Tf binds to cell surface receptors, and is internalized into the para-Golgi region of the cell. Iron is released from Tf, and the apo-Tf and its receptor are recycled back to the cell surface. Thus, the TRV cells can be used to study the behavior of genetically altered Tf receptors in the absence of interfering effects from endogenous receptors.

Animals↗
PubMed2000

Upregulation of interleukin-10 and inhibition of alloantigen responses by transferrin and transferrin-derived glycans.

Previous studies have shown that critically timed administration of transferrin (Tf) facilitates induction of immunologic unresponsiveness. Here, we determined in mixed leukocyte culture (MLC) and in concanavalin A (ConA)-driven cultures the effect of exogenous Tf and Tf-derived glycans (Tf-Gly) on lymphocyte proliferation. In cultures of human blood lymphocytes, Tf inhibited selectively alloantigen-driven proliferation in MLC, but not ConA-stimulated lymphocyte proliferation. Deglycosylation of Tf abrogated the inhibitory effect of Tf on alloantigen-induced lymphocyte proliferation, and, consistent with a role for glycans, an effect qualitatively and quantitatively similar to Tf was exerted by purified Tf-Gly. Glycans isolated from other proteins, for example, immunoglobulin G (IgG) or fibrinogen, failed to inhibit alloantigen-induced proliferation selectively. Rather, they suppressed lymphocyte proliferation in a non-specific manner. Determination of cytokines in MLC supernatant showed a downregulation of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-2, and IL-12 (p40), along with an upregulation of IL-10, a pattern entirely consistent with the observed effects of Tf and Tf-Gly on alloantigen-induced lymphocyte proliferation. The effect of Tf on MLC was directly IL-10-dependent. IL-10 levels were inversely correlated with lymphocyte proliferation and CD86 expression. Neutralization of IL-10 by anti-IL-10 monoclonal antibody (mAb) blocked the effect of Tf. The MLC-modulating effect of Tf (or Tf-Gly) was not dependent upon the Tf receptor CD71 but appeared to be mediated by a Gly-responsive receptor. These data suggest a role of Tf, and, in particular, Tf-Gly, in allo-interactions that is independent from the role of Tf in iron metabolism, and appears to involve co-stimulatory signals.

Antibodies, Monoclonal↗
PubMed2005

Trypanosomes change their transferrin receptor expression to allow effective uptake of host transferrin.

In its mammalian host, Trypanosoma brucei covers its iron requirements by receptor-mediated uptake of host transferrin (Tf). The Tf-receptor (Tf-R) is a heterodimeric membrane protein encoded by expression site-associated gene (ESAG) 6 and 7 located promoter-proximal in a polycistronic expression site (ES). Each of the 20 ESs encodes a slightly different Tf-R; these differences strongly affect the binding affinity for Tfs of different hosts. The Tf-R encoded in the 221 ES has a low affinity for dog Tf. Transfer of trypanosomes with an active 221 ES to dilute dog serum leads to growth arrest, which they can overcome by switching to another ES encoding a Tf-R with higher affinity for dog Tf. Here we show that trypanosomes can also adapt to dilute dog serum without switching but by replacing the ESAG7 gene in the 221 ES by one from another ES, by deleting ESAG7 from the 221 ES with concomitant upregulation of transcription of ESAG7 in 'silent' ESs, by grossly overproducing the 221 Tf-R or by combinations of these alterations. Our results illustrate the striking genetic flexibility of trypanosomes.

Animals↗
PubMed1986

Subcellular characterization of the transferrin-transferrin receptor and iron accumulating system of established human erythroid and monoblastoid tumour cell lines.

The organelles in two human tumour cell lines in culture - U-937 and K-562 - involved in the receptor mediated endocytosis (RME) of transferrin (Tf) were studied after isolation from homogenates by density gradient separation. They were also studied by electron microscopy after labelling of living cells with Tf coated colloidal gold particles. Three different Tf containing fractions with densities 1.038 (plasma membrane), 1.040 (light endosomes) and 1.051 g/ml (heavy endosomes) were identified. Ultrastructural studies of the distribution of gold label indicated that Tf was present in structures normally involved in RME of other ligands, probably including the recently identified "compartment of uncoupling of receptor-ligand complex" (CURL). The endocytosed iron was found to be rapidly transferred into the cytosol, as shown by density gradient centrifugation. Isoelectric focusing analysis showed that the iron mainly became bound in ferritin. In the hemoglobin synthesizing cell line K-562, however, iron was also inserted into hemoglobin. The finding that heavy and light endosomes process Tf suggests that Tf follows the same route as other ligands, including the epidermal growth factor and low density lipoprotein, in a presumed prelysosomal pathway, despite the fact that Tf does not dissociate from its receptor. Our findings are thus consistent with the notion that an endosome system similar to that in other types of RME is responsible for the cleavage and separation of iron from the carrier Tf.

Cell Line↗
PubMed1990

N-linked oligosaccharides of human transferrin are not required for binding to bacterial transferrin receptors.

Derivatives of human transferrin (hTf) with removed or modified N-linked oligosaccharides were compared with native hTf with respect to their binding to bacterial hTf receptors from Neisseria meningitidis, N. gonorrhoeae, and Haemophilus influenzae. Partially and fully deglycosylated hTf were prepared by enzymatic deglycosylation with glycopeptidase F and isolated by concanavalin A-Sepharose affinity chromatography. Oligosaccharide-modified hTf was prepared via mild periodate oxidation. Competition and direct binding experiments with the hTf derivatives demonstrated that the hTf oligosaccharides are not essential for binding to the bacterial hTf receptors.

Amidohydrolases↗
PubMed2004

Transferrin receptor 2 mediates a biphasic pattern of transferrin uptake associated with ligand delivery to multivesicular bodies.

The physiological role of transferrin (Tf) receptor 2 (TfR2), a homolog of the well-characterized TfR1, is unclear. Mutations in TfR2 result in hemochromatosis, indicating that this receptor has a unique role in iron metabolism. We report that HepG2 cells, which endogenously express TfR2, display a biphasic pattern of Tf uptake when presented with ligand concentrations up to 2 muM. The apparently nonsaturating pathway of Tf endocytosis resembles TfR1-independent Tf uptake, a process previously characterized in some liver cell types. Exogenous expression of TfR2 but not TfR1 induces a similar biphasic pattern of Tf uptake in HeLa cells, supporting a role for TfR2 in this process. Immunoelectron microscopy reveals that while Tf, TfR1, and TfR2 are localized in the plasma membrane and tubulovesicular endosomes, TfR2 expression is associated with the additional appearance of Tf in multivesicular bodies. These combined results imply that unlike TfR1, which recycles apo-Tf back to the cell surface after the release of iron, TfR2 promotes the intracellular deposition of ligand. Tf delivered by TfR2 does not appear to be degraded, which suggests that its delivery to this organelle may be functionally relevant to the storage of iron in overloaded states.

Antigens, CD↗
PubMed1992

Characterization of early and late endocytic compartments of the transferrin cycle. Transferrin receptor antibody blocks erythroid differentiation by trapping the receptor in the early endosome.

We describe a detailed morphological characterization of the endocytic pathway in differentiating chicken erythroblasts transformed by a temperature-sensitive mutant of avian erythroblastosis virus (AEV). These cells express high levels of transferrin receptors (TfR) when induced to differentiate at 42 degrees C. Biochemical analysis showed that most (approximately 90%) of the internalized 125I-Tf recycled within approximately 30 min while a smaller fraction of 125I-Tf required up to 2 h for recycling. By immunocytochemistry, the bulk of Tf and TfR was localized at the plasma membrane and in tubuloreticular early endosomes. This structure contained coated buds that labelled with an antibody specific for the clathrin light chain. Decreasing amounts of both Tf and TfR were detected in two distal compartments, spherical endosome vesicles resembling multivesicular bodies and the prelysosomal compartment (PLC) enriched in cation-independent mannose 6-phosphate receptor. As shown by fluorescent (FITC-Tf) labelling of living cells, the movement of Tf/TfR complex into these late structures was accompanied by a significant drop in pH from about 6, the value displayed by early endosomes, to values below pH 5.0. Since no detectable 125I-Tf degradation was observed during a 4 h period we believe that the Tf/TfR detected in these late endocytic structures avoids degradation and recycles back to the cell surface. The addition of an anti-TfR monoclonal antibody to the culture medium of these cells blocks their differentiation. Under this condition the antibody-TfR complex was trapped in an early endosome compartment that enlarged to more than twice its normal size. However, this condition did not affect the transport kinetics of horseradish peroxidase from the medium to the PLC.

Alpharetrovirus↗
PubMed1999

Targeting of transferrin receptors in nude mice bearing A431 and LS174T xenografts with [18F]holo-transferrin: permeability and receptor dependence.

UNLABELLED: The goal of this study was to investigate whether 18F-labeled transferrin (Tf), which has a molecular weight (Mr) of approximately 79,000, binds to Tf receptor sites in tumors in a specific manner within the time frame commensurate with the half-life of 18F (109.7 min). We have previously shown that [18F]holo-Tf ([18F]Tf) maintains all properties of native Tf in vitro and that it can specifically target liver Tf receptor sites in vivo. METHODS: The distribution of [18F]Tf, using [18F]albumin (Alb) or [14C]Alb as a control, was studied over a 6-h period in nude mice bearing LS174T and A431 xenografts of a high- and low-permeability tumor, respectively. RESULTS: Measurements of Tf receptor concentration in the tumor extracts suggest similar binding capacities. In vivo, liver uptake values were higher for [18F]Tf than for both [18F]Alb and [14C]Alb throughout the study, indicating specific binding. In contrast, tumor Tf uptake values remained below those of the Alb tracers, and tumor-to-blood ratios of [18F]Tf in each xenograft increased in parallel with those of the Alb tracers. The permeabilities of [14C]Alb and [18F]Tf in LS174T were calculated to be 1.29+/-0.49 and 1.03+/-0.38 microL/min/g (mean +/- SD), respectively, whereas the permeabilities of the two tracers in A431 were 0.79+/-0.24 and 0.44+/-0.04 microL/min/g. Pharmacokinetic modeling of the data using these permeabilities and the high plasma and extracellular concentrations of endogenous Tf showed that the observed uptake values in the two xenografts are consistent with a non-receptor-mediated distribution. In the liver, the absence of permeability barriers yields specific [18F]Tf binding to receptors compared with the [14C]Alb control, within 5 min after injection. CONCLUSION: Receptor-mediated accumulation of [18F]Tf in tumor xenografts is impaired by rate-determining permeability and competition from endogenous Tf and is not achieved in a time frame of 6 h.

Albumins↗
PubMed1987

Role of the transferrin receptor in lymphocyte growth: a rat IgG monoclonal antibody against the murine transferrin receptor produces highly selective inhibition of T and B cell activation protocols.

We have produced a new rat IgG monoclonal antibody against the murine transferrin receptor (TR). This antibody (C2F2) exhibits a surprisingly selective pattern of inhibition of murine lymphocyte activation protocols. C2F2 inhibits the mixed lymphocyte reaction (MLR) and the generation of cytotoxic T cells. Interestingly, although interleukin 1 (IL 1)-dependent thymocyte co-stimulatory activity is strongly inhibited by C2F2, interleukin 2 (IL 2)-dependent thymocyte co-stimulation is only marginally reduced. IL 2-dependent growth of CTLL cells is also not inhibited by C2F2. These data suggest that IL 1-dependent helper T cell activation is very sensitive to C2F2-mediated inhibition. Studies with phytohemagglutinin, Concanavalin A, and lipopolysaccharide induced activation also indicate that the inhibitory effects of C2F2 are selective, and T cell activation may be more sensitive to inhibition than B cell activation. Although there is little published information about the functional effects of other rat anti-mouse TR antibodies, the available data suggest that the patterns of inhibition produced by anti-TR antibodies may be individually distinct. Anti-TR antibodies may constitute a new set of highly selective probes for the study of lymphocyte activation.

Animals↗
PubMed1986

Desialation of transferrin by liver endothelium: evidence for two cellular pathways for transferrin metabolism.

Transferrin was double-labeled, with its sialic acid residues being labeled with 3H and its protein part with either 125I or 59Fe. Incubation of this double-labeled molecule with fractionated liver endothelium led to the dissociation of the two labels, with 3H being retained and 59Fe and 125I being released from the cell, demonstrating similar patterns. Similar incubation of the double-labeled molecule with K562 cells did not lead to the dissociation of the two labels. The findings provide evidence that liver endothelium desialates Fe-TF complexes and releases the desialated TF still in association with Fe. The findings also provide evidence for a difference in the metabolic pathway of TF in different cell types.

Animals↗
PubMed1984

Endocytosis and intracellular processing of transferrin and colloidal gold-transferrin in rat reticulocytes: demonstration of a pathway for receptor shedding.

Endocytosis and intracellular processing of transferrin (Tf) and Tf receptors were examined in rat reticulocytes. Subcellular fractionation revealed that Tf enters a non-lysosomal endocytic compartment with a density between those of plasma membrane and lysosomes. After 20 min of uptake at (37 degrees C) 35 to 40% of cell-associated Tf was contained in this intermediate-density compartment. To test the fidelity of colloidal gold-Tf (AuTf) as a probe for Tf processing, reticulocytes were fractionated after uptake of 131I-Tf and 125I-AuTf. The subcellular distributions of the two ligands were indistinguishable by this method, a result suggesting that AuTf is processed similarly to Tf. Electron microscopy revealed that AuTf entered multivesicular endosomes (MVEs) as well as various small vesicles and tubular structures. In addition MVE exocytosis was observed with discharge of inclusion vesicles and associated AuTf. AuTf was bound to the outside of these vesicles both before and after exocytosis. These data suggest that Tf receptors are shed from developing reticulocytes by incorporation into the limiting membrane of inclusion vesicles, followed by discharge of these vesicles by MVE exocytosis. As further evidence of this process, we isolated inclusion vesicles after their discharge and found them to contain Tf receptors. Moreover, the rate of Tf receptor shedding by inclusion vesicle discharge matches Tf receptor loss rates closely enough to suggest that this is the primary path of receptor loss during reticulocyte development.

Animals↗
PubMed1996

Transferrin modifies surfactant responsiveness in acute respiratory failure: role of iron-free transferrin as an antioxidant.

In respiratory failure, transferrin (TF) with variable iron saturation accumulates in the alveolar space. Binding free iron to TF may inhibit metal-catalyzed formation of free radicals. The aim of this study was to evaluate whether the degree of the iron-saturation of TF influences the severity of respiratory failure and surfactant responsiveness. Surfactant deficiency and lung edema was induced in 42 paralyzed and ventilated young rabbits by bronchoalveolar lavage (BAL); 19 of these animals were preexposed to 100% O2 for 40 hours. The animals received (1) exogenous surfactant intratracheally (100 mg/kg in 4 ml/kg saline); (2) surfactant and Fe(3+)-TF (50 or 25 mg/kg); or (3) surfactant and iron-free TF (50 mg/kg). One hour after administration of TF, 13-25% of exogenous TF was recovered by BAL. Administration of Iron-free TF significantly decreased the iron saturation of TF in BAL. In acute respiratory failure induced by BAL, Fe(3+)-TF decreased the efficacy of exogenous surfactant in improving the gas exchange, and increased surfactant inhibition, while iron-free TF had no effect. By contrast, in respiratory failure induced by hyperoxia and BAL, iron-free TF improved the efficacy of exogenous surfactant, but Fe(2+)-TF had no effect. After administration of iron-free TF, surfactant isolated from BAL was more surface-active than surfactant from BAL of the other hyperoxia-treated animals. In animals exposed to hyperoxia, treatment with iron-free TF decreased malondialdehyde content of BAL. We propose that low iron saturation of TF decreases oxidant stress and favors the recovery from respiratory failure.

Acute Disease↗
PubMed2000

Single values of serum transferrin receptor and transferrin receptor ferritin index can be used to detect true and functional iron deficiency in rheumatoid arthritis patients with anemia.

OBJECTIVE: To elucidate the use of serum transferrin receptor (sTfR) to distinguish between iron-deficiency anemia (IDA) and anemia of chronic disease (ACD), and to establish an improved scheme to identify functional iron deficiency (FID) in rheumatoid arthritis (RA) patients with anemia. METHODS: We studied 30 anemic RA patients whose iron status was confirmed by bone marrow examination and determination of the sTfR level, serum ferritin level, and sTfR-log ferritin index (TfR-F Index). All patients with diminished or exhausted iron stores (n = 18) received oral iron supplementation. RESULTS: Baseline values of sTfR and the TfR-F Index predicted the response correctly in all patients who received supplementation treatment and were normal in 10 of 11 patients with normal initial iron stores (ACD). CONCLUSION: The results of this study elucidate the roles of sTfR and the TfR-F Index in the differential diagnosis between IDA and ACD and provide direct evidence that these parameters are useful in detecting FID, irrespective of the concurrent iron storage status.

Anemia, Iron-Deficiency↗
PubMed1994

Further evidence of different lactoferrin and transferrin binding sites on human HT29-D4 cells. Effects of lysozyme, fucose and cathepsin G. Comparison with transferrin.

We have defined by using competition experiments the nature of specific lactoferrin binding sites, probably responsible for the previously observed stimulatory growth effect of the iron binding protein on HT29-D4 cells. Lysozyme, albumin and fucose do not affect lactoferrin binding showing that the binding of the protein is mediated neither by electrostatic forces nor by fucose. Iron-free and iron-loaded protein produce similar effects, demonstrating that the metal is not involved in the protein recognition. Similar results are observed for transferrin. A specific binding inhibition of lactoferrin by cathepsin G, a leukocyte proteinase, is observed, suggesting the existence of a common receptor for lactoferrin and cathepsin G on HT29-D4 cells. These results and the fact that tumor tissues are more often infiltrated by inflammatory cells such as polymorphonuclear leukocytes could evoke an unexpected role for leukocytes, possibly mediated in part by these two proteins, on the proliferative cancer effect.

Binding Sites↗
PubMed2004

Increased levels of serum transferrin receptor and serum transferrin receptor/log ferritin ratios in men with prostate cancer and the implications for body-iron stores.

The serum transferrin receptor (sTfR) is a sensitive indicator of iron-deficiency erythropoiesis that is not affected by inflammation. Concentrations of this molecule are inversely correlated with body-iron stores, and increased body-iron stores are associated with an increased risk of cancer of the liver and lungs. However, an association between iron status as assessed on the basis of sTfR and prostate cancer has not been previously investigated. We measured sTfR and serum ferritin by means of an enzyme immunoassay in 27 men with newly diagnosed, untreated prostate cancer and in 72 controls. Our study population ranged in age from 38 to 78 years. The mean serum ferritin concentration in men with prostate cancer was 44.8% lower than that in men without this tumor ( P < .05). In contrast, the mean values of sTfR and sTfR/log serum ferritin were 32% and 60% higher, respectively, in men with prostate cancer than in those without this tumor ( P < .05). Differences between groups persisted after we took into account inflammation (alpha 1-acid glycoprotein > 1 g/L, C-reactive protein > 10 mg/L; P < .05). Among the entire study population and among men without inflammation, a higher percentage of subjects (29%-31%) than of controls (14%-22%) had sTfR values greater than 8 mg/L, suggestive of iron-deficiency erythropoiesis ( P < .05). The odds ratios for men with prostate cancer to have sTfR values of less than 2.9 mg/L (suggestive of increased body-iron stores) was 0, compared with 1.745 to 3.65 for the same men to have sTfR values greater than 8 mg/L. sTfR was negatively correlated with log ferritin ( r = -.422, P < .05) but did not correlate with tissue inflammation, tumor stage, or acute-phase proteins. It appears that prostate cancer is not associated with increased body-iron stores.

Adult↗