Effects of insulin and transferrin on the generation of lymphokine-activated killer cells in serum-free medium

Potential treatment of squamous cell carcinoma by targeting heparin-binding protein 17/fibroblast growth factor-binding protein 1 with vitamin D3 or eldecalcitol

Heparin-binding protein 17 (HBp17), first purified in 1991 from the conditioned medium of the human A431 squamous cell carcinoma (SCC) cell line, was later renamed fibroblast growth factor-binding protein 1 (FGFBP-1). HBp17/FGFBP-1 is specifically expressed and secreted by epithelial cells, and it reversibly binds to fibroblast growth factor (FGF)-1 and FGF-2, as well as FGFs-7, -10, and -22, indicating a crucial involvement in the transportation and function of these FGFs. Our laboratory has investigated and reported several studies to elucidate the function of HBp17/FGFBP-1 in SCC cells and its potential as a molecular therapeutic target. HBp17/FGFBP-1 transgene exoression in A431-4 cells, a clonal subline of A431 that lacks tumorigenicity and does not express HBp17/FGFBP-1, demonstrated a significantly enhanced proliferation in vitro compared with A431-4 cells, and it acquired tumorigenicity in the subcutis of nude mice. Knockout (KO) of the HBp17/FGFBP-1 by genome editing significantly suppressed tumor growth, cell motility, and tumorigenicity compared with control cells. A comprehensive analysis of expressed molecules in both cell types revealed that molecules that promote epithelial cell differentiation were highly expressed in HBp17/FGFBP-1 KO cells. Additionally, we reported that 1α,25(OH)2D3 or eldecalcitol (ED-71), which is an analog of 1α,25(OH)2D3, suppresses HBp17/FGFBP-1 expression and tumor growth in vitro and in vivo by inhibiting the nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway. Here, we discuss the prospects of molecular targeted therapy targeting HBp17/FGFBP-1 with 1α,25(OH)2D3 or ED71 in SCC and oral SCC.

Pathophysiological aspects of transferrin-A potential nano-based drug delivery signaling molecule in therapeutic target for varied diseases

Transferrin (Tf), widely known for its role as an iron-binding protein, exemplifies multitasking in biological processes. The role of Tf in iron metabolism involves both the uptake of iron from Tf by various cells, as well as the endocytosis mediated by the complex of Tf and the transferrin receptor (TfR). The direct conjugation of the therapeutic compound and immunotoxin studies using Tf peptide or anti-Tf receptor antibodies as targeting moieties aims to prolong drug circulation time and augment efficient cellular drug uptake, diminish systemic toxicity, traverse the blood-brain barrier, restrict systemic exposure, overcome multidrug resistance, and enhance therapeutic efficacy with disease specificity. This review primarily discusses the various biological actions of Tf, as well as the development of Tf-targeted nano-based drug delivery systems. The goal is to establish the use of Tf as a disease-targeting component, accentuating the potential therapeutic applications of this protein.

Establishment of induced pluripotent stem cells derived from patients and healthy siblings of a nevoid basal cell carcinoma syndrome family

It is known that a nevoid basal cell carcinoma syndrome (NBCCS) is characterized by a combination of developmental abnormalities and a predisposition to form various tumors. Although it is possible to create disease models via gene editing, there are significant potential problems with this approach such as off-target mutations and differences in SNPs. On the other hand, since disease families share common SNPs, research using iPSCs derived from both patients and healthy siblings of the same disease family is very important. Thus, establishment of induced pluripotent stem cells derived from patients and healthy siblings of the same NBCCS family will be of great importance to study the etiology of this disease and to develop therapeutics. In this study, we generated hiPSCs using peripheral blood mononuclear cells derived from the patients and healthy siblings of familial NBCCS with the novel mutation in PTCH1_c.3298_3299insAAG in the feeder- and serum-free culture conditions using SeVdp. In addition, disease-specific hiPSCs such as those expressing the PTCH1_c.3298_3299insAAG mutation could be powerful tools for revealing the genotype-phenotype relationship and pathogenicity of NBCCS.

Development of a modified serum-free medium for Vero cell cultures: effects of protein hydrolysates, l-glutamine and SITE liquid media supplement on cell growth

Vero cells have been widely used in the viral vaccine production due to the recommendation of the World Health Organization regarding its safety and non-tumorigenicity. The aim of this study was to describe the development a modified serum-free medium for Vero cell cultures. Two protein hydrolysates (Bacto™ soytone and Bacto™ yeast extract), vitamin C, vitamin B12, SITE liquid media supplement, and recombinant human epidermal growth factor (rEGF) were investigated as serum substitutes. A sequential experiment of fractional factorial and central composite design was applied. A modified serum-free medium obtained (named as SFM01-M) was verified. Contrary to P0, the cell yields obtained at P1, P2, and P3 decreased continuously during the verification experiments indicating that Vero cells could not adapt to SFM01-M as expected according to the empirical mathematical model. To improve cell growth after P0, protein hydrolysates, l-glutamine, and SITE liquid media supplement were further investigated. The results showed that cell yields gradually decreased from P1 to P3 when a fixed concentration of Bacto™ yeast extract (7.0 g/L) combined with various concentrations of Bacto™ soytone (0.1-7.0 g/L) in SFM01-M were used. Similarly, cell yields also gradually decreased from P1 to P3 when a fixed concentration of Bacto™ soytone (7.0 g/L) combined with various concentrations of Bacto™ yeast extract (0.1-7.0 g/L) in SFM01-M were used. However, the combination of Bacto™ soytone at 0.1 g/L and Bacto™ yeast extract at 7.0 g/L or Bacto™ soytone at 7.0 g/L and Bacto™ yeast extract at 0.1 g/L in SFM01-M could give the maximum cell yield at P3 when compared with other combinations. In addition, the addition of SITE liquid media supplement (0.1-2.0% v/v) in SFM01-M in which the concentrations of Bacto™ soytone, Bacto™ yeast extract, and l-glutamine were fixed at 0.1 g/L, 0.1 g/L, and 4.0 mM, respectively, the results showed that the cell yields obtained at P3 were not significantly different. From this study, the optimum concentrations of SFM01-M components were as follows: Bacto™ soytone (0.1 g/L), Bacto™ yeast extract (0.1 g/L), vitamin C (9.719 mg/L), vitamin B12 (0.1725 mg/L), SITE liquid media supplement (0.1-2.0% v/v), rEGF (0.05756 mg/L), l-glutamine (4.0 mM), MEM non-essential amino acids (1.0% v/v), sodium pyruvate (1.0 mM), MEM (9.4 g/L), and sodium hydrogen carbonate (2.2 g/L). However, to evaluate SFM01-M in the long-term subculture of Vero cells, the efficiency of SFM01-M will be further investigated.

Heparin-Binding Protein 17/Fibroblast Growth Factor-Binding Protein-1 Knockout Inhibits Proliferation and Induces Differentiation of Squamous Cell Carcinoma Cells

Simple Summary

Fibroblast growth factor (FGF) plays an important role in tumor growth by inducing angiogenesis in addition to promoting the proliferation of squamous cell carcinoma (SCC) and oral squamous cell carcinoma (OSCC) cells. Heparin-binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1) purified from A431 cell-conditioned media based on its capacity to bind to FGF-1 and FGF-2 is recognized as a pro-angiogenic molecule as a consequence of its interaction with FGF-2. In this study, we have examined the functional role of HBp17/FGFBP-1 in A431 and HO-1-N-1 cells using the CRISPR/Cas9 technology. Our results showed that HBp17/FGFBP-1 knockout inhibited cell proliferation, colony formation, and cell motility compared to control. The amount of FGF-2 was decreased in culture medium conditioned by HBp17/FGFBP-1 knockout cells compared to control. We performed cDNA/protein expression analysis followed by Gene Ontology and protein–protein interaction analysis. The results demonstrate that both gene and protein expression related to epidermal development, cornification, and keratinization were upregulated in HBp17/FGFBP-1-knockout A431 and HO-1-N-1 cells.

Abstract

Heparin-binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1) has been observed to induce the tumorigenic potential of epithelial cells and is highly expressed in oral cancer cell lines and tissues. It is also recognized as a pro-angiogenic molecule because of its interaction with fibroblast growth factor (FGF)-2. In this study, we examined the functional role of HBp17/FGFBP-1 in A431 and HO-1-N-1 cells. Originally, HBp17/FGFBP-1 was purified from A431 cell-conditioned media based on its capacity to bind to FGF-1 and FGF-2. We isolated and established HBp17/FGFBP-1-knockout (KO)-A431 and KO-HO-1-N-1 cell lines using the clusters of regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) gene editing technology. The amount of FGF-2 secreted into conditioned medium decreased for A431-HBp17-KO and HO-1-N-1-HBp17-KO cells compared to their WT counterparts. Functional assessment showed that HBp17/FGFBP-1 KO inhibited cell proliferation, colony formation, and cell motility in vitro. It also inhibited tumor growth in vivo compared to controls, which confirmed the significant difference in growth in vitro between HBp17-KO cells and wild-type (WT) cells, indicating that HBp17/FGFBP-1 is a potent therapeutic target in squamous cell carcinomas (SCC) and oral squamous cell carcinomas (OSCC). In addition, complementary DNA/protein expression analysis followed by Gene Ontology and protein–protein interaction (PPI) analysis using the Database for Visualization and Integrated Discovery and Search Tool for the Retrieval of Interacting Genes/Proteins showed that both gene and protein expression related to epidermal development, cornification, and keratinization were upregulated in A431-HBp17-KO and HO-1-N-1-KO cells. This is the first discovery of a novel role of HBp17/FGFBP-1 that regulates SCC and OSCC cell differentiation.

Enhanced KRT13 gene expression bestows radiation resistance in squamous cell carcinoma cells

Cancer metastasis and recurrence are potentially lethal. A small number of cancer cell groups called cancer stem cells (CSCs) have both stem cell capacity and cancer-forming ability and are reported to play important roles in cancer metastasis and recurrence. These CSCs are considered to be radiation-resistant (RR). Therefore, understanding the biological effects of radiation on squamous cell carcinoma (SCC) cell lines in vitro and in vivo might be worthwhile to circumvent radiation resistance. Currently, there are no reports on the establishment of RR-SCC cells in serum-free defined culture, which mimics biological mechanisms and prevents instability of using serum in the culture medium. We isolated radiation-resistant strains, designated A431-LDR and A431-HDR, from A431 cells derived from vulval SCC and irradiated them with a total dose of 60 Gy at a low-dose rate (2.2 Gy/d) (RM1000) and a high-dose rate (5 Gy/5.75min) in serum-free defined culture. These cells exhibited high sphere-forming and migration ability in vitro and high tumor-forming ability in nude mice xenografts. Overexpression of KRT13 in A431-RR cells might play a role in its radiation-resistant characteristics. These cells might be useful not only to study cancer stem cells but also to study the circumvention of radiation resistance by novel cancer treatment modalities.

Eldecalcitol (ED-71)-induced exosomal miR-6887-5p suppresses squamous cell carcinoma cell growth by targeting heparin-binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1)

Heparin-binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1) was purified from A431 cell-conditioned media based on its capacity to bind to fibroblast growth factor 1 and 2 (FGF-1 and FGF-2). HBp17/FGFBP-1 has been observed to induce the tumorigenic potential of epithelial cells and is highly expressed in oral cancer cell lines and tissues. HBp17/FGFBP-1 is also recognized as a pro-angiogenic molecule as a consequence of its interaction with FGF-2. We have previously reported that Eldecalcitol (ED-71), an analog of 1α,25(OH)₂D₃, downregulated the expression of HBp17/FGFBP-1 and inhibited the proliferation of squamous cell carcinoma (SCC) cells in vitro and in vivo through NF-κb inhibition. To explore the possibility of microRNA (miRNA) control of HBp17/FGFBP-1, we analyzed exosomal miRNAs from medium conditioned by A431 cells treated with ED-71. Microarray analysis revealed that 12 exosomal miRNAs were upregulated in ED-71-treated A431 cells. Among them, miR-6887-5p was identified to have a predicted mRNA target matching the 3' untranslated region (3'-UTR) of HBp17/FGFBP-1. The 3'-UTR of HBp17/FGFBP-1 was confirmed to be a direct target of miR-6887-5p in SCC/OSCC cells, as assessed with a luciferase reporter assay. Functional assessment revealed that overexpression of miR-6887-5p in SCC/OSCC cells inhibited cell proliferation and colony formation in vitro, and inhibited tumor growth in vivo compared with control. In conclusion, our present study supports a novel anti-cancer mechanism involving the regulation of HBp17/FGFBP-1 function by exosomal miR-6887-5p in SCC/OSCC cells, which has potential utility as a miRNA-based cancer therapy.

Induction of integration-free human-induced pluripotent stem cells under serum- and feeder-free conditions

Human-induced pluripotent stem cells (hiPSCs) have shown great potential toward practical and scientific applications. We previously reported the generation of human dental pulp stem cells using non-integrating replication-defective Sendai virus (SeVdp) vector in feeder-free culture with serum-free medium hESF9. This study describes the generation of hiPSCs from peripheral blood mononuclear cells to increase the donor population, while reducing biopsy invasiveness. From 6-d-old primary culture of peripheral blood mononuclear cells (PBMCs) with IL-2, hiPSCs were established using SeVdp(KOSM)302L with recombinant Laminin-511 E8 fragments under serum-free condition. The established PBMC-derived hiPSCs showed pluripotency and differentiation ability both in vivo and in vitro. In addition, we evaluated microarray data from PBMC- and dental pulp–derived hiPSCs. These hiPSCs will be beneficial for characterizing the molecular mechanisms of cellular differentiation and may provide useful substrates for developing cellular therapeutics.

Eldecalcitol (ED-71), an analog of 1α,25(OH)2D3, inhibits the growth of squamous cell carcinoma (SCC) cells in vitro and in vivo by down-regulating expression of heparin-binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1) and FGF-2

Heparin-binding protein 17 (HBp17)/fibroblast growth factor-binding protein-1 (FGFBP-1) was first purified from medium conditioned by A431 cells for its capacity to bind to fibroblast growth factors 1 and 2 (FGF-1 and -2). Among FGF family members, FGF-2 is a potent mitogen for various cell types, including vascular endothelial cells, fibroblasts, and cancer cells such as oral squamous cell carcinoma (OSCC) cells. Besides being well known in bone metabolism, the active form of vitamin D₃, i.e., 1α,25(OH)₂D₃ (1,25D₃), was reported to have protective effects for heart disease and cancer. Previously, we reported that 1,25D₃ inhibited HBp17/FGFBP-1 expression in OSCC cell lines through NF-κB inhibition (IκBα activation) and resulted in the inactivation of FGF-2. In this study, we examined the potential anti-tumor effect of ED-71, an analog of 1α,25(OH)₂D₃, for squamous cell carcinoma cells in vitro and in vivo. The cell lines used were OSCC cell lines (NA-HO-1-n-1 and UE-HO-1-u-1), established from oral cancer patients in our laboratory, and an epidermoid carcinoma/SCC cell line (A431). The growth assay in serum-free culture revealed that ED-71 inhibited the growth of the cancer cell lines in a dose-dependent manner. In addition, ED-71 suppressed HBp17/FGFBP-1 expression by inhibiting the NF-κB pathway as did 1,25D₃. Furthermore, a luciferase reporter assay revealed that the promoter activity of HBp17/FGFBP-1 (region between -217 and +61) was down-regulated by ED-71. Oral administration of ED-71 significantly inhibited the growth of A431-derived tumors in athymic nude mice. Immunohistochemical analysis revealed that the expression of HBp17/FGFBP-1, FGF-2, CD31, and Ki-67 in the tumors of ED71-treated group was down-regulated in comparison to control. These results suggest that ED-71 possesses potential anti-tumor activity for SCCs both in vitro and in vivo. This compound may act directly on the tumor cells or on endothelial cells by modulating the tumor microenvironment.

Eldecalcitol (ED-71), an analog of 1α,25-dihydroxyvitamin D3 as a potential anti-cancer agent for oral squamous cell carcinomas

We have previously reported that 1,25(OH)₂D₃ inhibits NF-κB activity and thus inhibits growth of OSCC cells in serum-free culture and down-regulates HBp17/FGFBP-1 expression, which is important for cancer cell growth and angiogenesis. Here, we have investigated the effects of ED-71, an analog of vitamin D3 (VD) on OSCC cell lines in serum-free culture. It is known that ED-71 has a stronger inhibitory effect on bone resorption compared to VD and other VD analogs. To the best of our knowledge, there was no report examining the potential of ED-71 as an anti-cancer agent for OSCC. We found that ED-71 is able to inhibit the growth of cancer cell lines at a concentration of hundred times lower than calcitriol. As Cyp24A1 was reportedly induced in cancer cells, we measured the expression of CYP24A1 in OSCC cell lines (NA and UE), A431 epidermoid carcinoma and normal fibroblast cell (gfi) in serum-free culture. As a result, CYP24A1 mRNA and the protein expression in the OSCC cells treated with ED-71 increased in a dose-dependent manner. However, in vivo experiment, in which the A431 cells were implanted in mice, tumor formation was reduced by the ED-71 treatment with no significant difference between Cyp24A1 expression in the tumors of ED-71-treated and control group, as analyzed by western blotting and immunohistochemistry. These results suggest that ED-71 is a potential anti-cancer agent for OSCC.

1α,25OH2D3 down-regulates HBp17/FGFBP-1 expression via NF-κB pathway

The heparin binding protein 17/fibroblast growth factor-binding protein-1 (HBp17/FGFBP-1, GenBank accession no. NP-005121) has been reported to enhance angiogenesis as well as promotes tumor growth in vivo. Furthermore, this molecule was found to be highly expressed in the tissue and cell lines of oral squamous cell carcinoma (OSCC). 1α,25(OH)2D3 is used to study its potential to curb the expression of HBp17/FGFBP-1 in cancer cells. Consequently, we found that HBp17/FGFBP-1 mRNA and protein levels were significantly down-regulated. In this present study, we show that this event takes place via the NF-κB pathway since mRNA and protein levels of this pathway regulator, IκBα, were found to be significantly up-regulated. Furthermore, the promoter activity of HBp17/FGFBP-1 (region between -217 and +61) measured by a luciferase reporter assay was down-regulated following treatment. Silencing of VDR with siRNA showed the effect of 1α,25(OH)2D3 on HBp17/FGFBP-1. Based on these findings, we concluded that 1α,25(OH)2D3 down-regulated HBp17/FGFBP-1 expression via NF-κB. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Effects of supplementation of various medium components on chinese hamster ovary cell cultures producing recombinant antibody

Thirteen vitamins, twenty amino acids, hormones, inorganic salts, and other chemical agents, which constitute typical serum-free media, were evaluated for the development of fortified medium to enhance cell growth and productivity of recombinant antibody in the cultures of the recombinant Chinese hamster ovary (rCHO) cells. Two different rCHO cell lines, rCHO-A producing recombinant antibodies against the human platelet and rCHO-B secreting recombinant antibodies against the S surface antigen of Hepatitis B, respectively, were cultivated in batch suspension mode. Concentration of interested component in the tested medium was doubled to examine the fortification effect. Growth of rCHO-A cell and its antibody production were slightly improved with addition of either choline chloride, folic acid, thiamine[Symbol: see text]HCl, or Long(TM)R(3)IGF-I. On the other hand, in the cultivation of rCHO-B cell which was more sensitive to its environmental changes, hormones such as Long(TM)R(3)IGF-I and triiodothyronine (T(3)) as well as various vitamins involving choline chloride, i-inositol, niacinamide, pyridoxine HCl, and thiamine[Symbol: see text]HCl enhanced the cell growth and antibody production. Particularly, when concentration of consuming amino acid was doubled, remarkable increase in specific productivity was served, resulting in high final antibody concentration. These results were believed to provide a fundamental strategy of medium fortification useful for improvement of recombinant antibody production in serum-free medium.

Culture and Stimulation of Tammar Wallaby Lymphocytes

We describe the culture and stimulation of lymphocytes from the model marsupial, the tammar wallaby (Macropus eugenii). We also describe the capacity of tammar wallaby lymphocytes isolated from blood, spleen and lymph nodes to produce soluble immunomodulatory factors. Culture conditions were optimized for mitogen-driven stimulation using the plant lectin phytohaemagglutinin (PHA). Products secreted by stimulated cells were harvested and crudely fractionated before they were added back to freshly isolated lymphocytes. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay, both stimulatory and inhibitory bioactive factors were detected in serum-free supernatants harvested from mitogen-treated peripheral blood mononuclear cells. This paper describes the capacity of leukocytes of the tammar wallaby to respond to mitogenic stimulation and to produce soluble, low-molecular-weight bioactive molecules that possess cytokine-like activity.

The role of recombinant proteins in the development of serum-free media

Early developments in serum-free media led to a variety of formulations in which components normally provided in serum and required for growth (insulin, transferrin, lipid supplements, trace elements) and poorly defined components (extracts, hydrolysates) were added to defined basal media. These additives were mostly animal-derived. Given recent concerns about TSEs (transmissible spongiform encephalopathies) and other adventitious agents, the drive in media formulations must be towards elimination of animal-origin materials while maintaining cell line productivity. The progress made towards removing animal-derived components and the use of recombinant proteins in serum-free media for mammalian cells is reviewed.

Evaluation of recombinant human transferrin (DeltaFerrin(TM)) as an iron chelator in serum-free media for mammalian cell culture

DeltaFerrin(TM), a yeast-derived recombinant human transferrin produced by Delta Biotechnology Ltd. (Nottingham UK), was found to be a suitable replacement for holo human transferrin in serum-free culture media of the MDCK cell line (chosen because of its transferrin dependence) in short-term screening assays. Long-term subculture was achieved with DeltaFerrin(TM) supporting growth equivalent to that of holo human transferrin. DeltaFerrin(TM) and a selection of chemical iron chelators were found in short-term assays to be equivalent to holo human transferrin in supporting growth of MDCK, BHK-21-PPI-C16 and Vero-PPI. In long-term subcultures, however, only DeltaFerrin(TM) was found to support cell growth in a manner essentially equivalent to holo human transferrin in all three cell lines. For both BHK and Vero variants tested, recombinant preproinsulin production was unaltered by replacing holo human transferrin with DeltaFerrin(TM). As such, this is the first report of a recombinant human transferrin produced under animal-free conditions that can act as a universal iron chelator for cells grown in serum-free media (SFM).

Transferrin: structure, function and potential therapeutic actions

There are many proteins that can multi-task. Transferrin, widely known as an iron-binding protein, is one such example of a multi-tasking protein. In this review, the multiple biological actions of transferrin, including its growth and cytoprotective activities, are discussed with the view of highlighting the potential therapeutic applications of this protein.

Long-term culture of Xenopus presumptive ectoderm in a nutrient-supplemented culture medium

Animal cap assay is a useful experimental model for investigating the activity of inducers in amphibian development. This assay has revealed that activin A is a potent mesoderm-inducing factor. However, it has been very difficult to induce highly differentiated tissues such as cartilage in a 3-4 day culture period. It was recently reported that jaw cartilage was induced in vitro in an animal cap that had been cultured for 14 days in Steinberg's solution using the sandwich culture method and activin A. Under these conditions, necrosis was occasionally observed in the explants. In this study, we have achieved long-term animal cap cultures in a nutrient-supplemented culture medium designated RDX. This medium was made by modifying the saline concentration of the RD medium previously developed as a basal medium for the serum-free culture of various kinds of mammalian cells. The explants cultured in RDX grew more vigorously compared with those in Steinberg's solution. RDX medium promoted a wider variety of tissue induction and gene expression in the animal caps than Steinberg's solution, and also increased the frequency of cartilage induction. Therefore, the supplemental nutrients may support and promote the differentiation of cartilage. This long-term culture method using RDX medium is useful for studying the differentiation of tissues or organs such as cartilage in vitro.

Transferrin is an insulin-like growth factor-binding protein-3 binding protein

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) possesses both growth-inhibitory and -potentiating effects on cells that are independent of IGF action and are mediated through specific IGFBP-3 binding proteins/receptors located at the cell membrane, cytosol, or nuclear compartments and in the extracellular matrix. We have here characterized transferrin (Tf) as one of these IGFBP-3 binding proteins. Human serum was fractionated over an IGFBP-3 affinity column, and a 70-kDa protein was eluted, sequenced, and identified (through database searching and Western immunoblot) as human Tf. Tf bound IGFBP-3 but had negligible affinity to the other five IGFBPs, and iron-saturated holo-Tf bound IGFBP-3 more avidly than unsaturated Tf. Biosensor interaction analysis confirmed that this interaction is specific and sensitive, with a high association rate similar to IGF-I, and suggested that binding occurs in the vicinity of the IGFBP-3 nuclear localization site. As an independent confirmation of this interaction, using a yeast two-hybrid system, we cloned Tf from a human liver complementary DNA library as an IGFBP-3 protein partner. Tf treatment blocked IGFBP-3-induced cell proliferation in bladder smooth muscle cells, and IGFBP-3-induced apoptosis in prostate cancer cells. In summary, we have employed a combination of techniques to demonstrate that Tf specifically binds IGFBP-3, and we showed that this interaction has important physiological effects on cellular events.

Monocyte-derived CD1a+ and CD1a- dendritic cell subsets differ in their cytokine production profiles, susceptibilities to transfection, and capacities to direct Th cell differentiation

We describe a phenotypically and functionally novel monocyte-derived dendritic cell (DC) subset, designated mDC2, that lacks IL-12 synthesis, produces high levels of IL-10, and directs differentiation of Th0/Th2 cells. Like conventional monocyte-derived DC, designated mDC1, mDC2 expressed high levels of CD11c, CD40, CD80, CD86, and MHC class II molecules. However, in contrast to mDC1, mDC2 lacked expression of CD1a, suggesting an association between cytokine production profile and CD1a expression in DC. mDC2 could be matured into CD83+ DC cells in the presence of anti-CD40 mAbs and LPS plus IFN-gamma, but they remained CD1a- and lacked IL-12 production even upon maturation. The lack of IL-12 and CD1a expression by mDC2 did not affect their APC capacity, because mDC2 stimulated MLR to a similar degree as mDC1. However, while mDC1 strongly favored Th1 differentiation, mDC2 directed differentiation of Th0/Th2 cells when cocultured with purified human peripheral blood T cells, further indicating functional differences between mDC1 and mDC2. Interestingly, the transfection efficiency of mDC2 with plasmid DNA vectors was significantly higher than that of mDC1, and therefore mDC2 may provide improved means to manipulate Ag-specific T cell responses after transfection ex vivo. Taken together, these data indicate that peripheral blood monocytes have the capacity to differentiate into DC subsets with different cytokine production profiles, which is associated with altered capacity to direct Th cell differentiation.