Purification and characterization of a low molecular weight transforming growth factor from the urine of melanoma patients

An automated RP-SCX solid-phase extraction procedure for urinary peptidomics biomarker discovery studies

Urine represents the most easily obtainable body fluid and consequently one of the most common samples in clinical chemistry. The majority of pathological changes in human organs may well be reflected in urine. In this way, urine analysis can aid in disease diagnosis, treatment monitoring, and prognosis. Currently, the most commonly used method for identification of new urine biomarkers involves centrifugation of the urine sample to collect either the soluble urine proteins or the urinary exosomes followed by 1 or 2 protein purification and separation steps before visualization and finally identification of potential biomarkers, usually by mass spectrometry. Here we present a generally applicable, rapid, and robust method for screening large number of urine samples, resulting in a broad spectrum of native peptides, as a tool to be used for biomarker discovery. The method combines online sample pretreatment with a well-established mass spectrometric technique. Native peptides are extracted from urine samples on a miniaturized reverse-phase-strong cation exchange cartridge system. As the proper identification of native peptides often requires combination of data acquired on different mass analyzers, we have aimed at a procedure providing us with sufficient material to identify and characterize the differentially expressed markers.

Transforming growth factor-beta and malignant melanoma: molecular mechanisms

Transforming growth factor family members (TGF-beta) are secretory polypeptides that have dual tumor-suppressor and oncogenic effects. They signal through kinase receptor complexes on the cell surface, which phosphorylate cytoplasmic mediators (SMADs). Upon phosphorylation, SMADs march to the nucleus and interact with coactivators or corepressors to mediate the transcriptional regulation of several genes resulting in diverse effects. In tumorigenesis, malignant cells escape from the tumor-suppressive effects of TGF-beta by mutational inactivation or dysregulated expression of the molecular components in TGF-beta signaling pathway. Although melanoma cells are resistant to the tumor-suppressive effects of TGF-beta, there are no detectable defects at the receptor/SMAD level. Therefore, in these lesions, it is possible that TGF-beta effects occur independently of TGF-beta receptor/SMAD pathway. This review seeks to examine the present knowledge about TGF-beta receptor/SMAD signaling pathway and its related genes (SMADs, SKI, Filamin, endoglin, Follistatin, and other molecules) in melanomas.

Modeling of neutral solute transport in a dynamically loaded porous permeable gel: implications for articular cartilage biosynthesis and tissue engineering

A primary mechanism of solute transport in articular cartilage is believed to occur through passive diffusion across the articular surface, but cyclical loading has been shown experimentally to enhance the transport of large solutes. The objective of this study is to examine the effect of dynamic loading within a theoretical context, and to investigate the circumstances under which convective transport induced by dynamic loading might supplement diffusive transport. The theory of incompressible mixtures was used to model the tissue (gel) as a mixture of a gel solid matrix (extracellular matrix/scaffold), and two fluid phases (interstitial fluid solvent and neutral solute), to solve the problem of solute transport through the lateral surface of a cylindrical sample loaded dynamically in unconfined compression with frictionless impermeable platens in a bathing solution containing an excess of solute. The resulting equations are governed by nondimensional parameters, the most significant of which are the ratio of the diffusive velocity of the interstitial fluid in the gel to the solute diffusivity in the gel (Rg), the ratio of actual to ideal solute diffusive velocities inside the gel (Rd), the ratio of loading frequency to the characteristic frequency of the gel (f), and the compressive strain amplitude (epsilon 0). Results show that when Rg > 1, Rd < 1, and f > 1, dynamic loading can significantly enhance solute transport into the gel, and that this effect is enhanced as epsilon 0 increases. Based on representative material properties of cartilage and agarose gels, and diffusivities of various solutes in these gels, it is found that the ranges Rg > 1, Rd < 1, correspond to large solutes, whereas f > 1 is in the range of physiological loading frequencies. These theoretical predictions are thus in agreement with the limited experimental data available in the literature. The results of this study apply to any porous hydrated tissue or material, and it is therefore plausible to hypothesize that dynamic loading may serve to enhance solute transport in a variety of physiological processes.

Urinary excretion of epidermal-type fatty acid-binding protein and S100A7 protein in patients with cutaneous melanoma

Epidermal-type fatty acid-binding protein (E-FABP), a protein related to the intracellular trafficking of fatty acids, is expressed in melanocytic tumours but not in normal human melanocytes. E-FABP interacts with S100A7. The presence of these two proteins was investigated in the urine of patients with cutaneous melanoma or other types of cancer, and healthy controls. The first voided morning urine samples of 31 patients with melanoma, 73 patients with other types of cancer and 17 healthy controls were concentrated and submitted to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) immunoblotting for protein detection. In the healthy controls, the incidences of urinary detection of these proteins were higher in females than in males, being 50% (five out of 10) versus 0% (zero out of seven) for E-FABP ( < 0.05), and 70% (seven out of 10) versus 0% (zero out of seven) for S100A7 ( < 0.05). Both proteins were detected in the urine of patients with melanoma. The incidence of S100A7 was higher in the urine of patients with melanoma (77%, 24 out of 31) compared with healthy controls (41%, seven out of 17) and patients with other types of cancer (53%, 39 out of 73) ( < 0.03). In contrast, the incidence of E-FABP was the same among the melanoma group (39%, 12 out of 31), healthy controls (29%, five out of 17) and patients with other types of cancer (23%, 17 out of 73). Surprisingly, E-FABP was always detected in the urine of females with stage I/II or III melanoma, but was no longer detectable in the urine of patients with stage IV melanoma. Urinary S100A7 may have some specificity to the host response to melanoma since its incidence was not increased in other cancers. The lack of E-FABP detection in the urine of patients with distant metastases suggests an inverse relationship between E-FABP release and the spread of melanoma.

Regulation of epidermal growth factor receptor expression in human melanocytes

The epidermal growth factor receptor (EGFR) and its ligand, transforming growth factor alpha (TGFalpha), are reportedly involved in autocrine growth of melanoma cells. The signal pathway has also been implicated in early events of transformation, suggesting a function for EGFR in normal cells. This study reports the presence of EGFR in cultured melanocytes and examines some cellular responses to TGFalpha. Western analysis revealed 170 kDa bands in extracts of cultured neonatal human melanocytes, corresponding to the receptor Mr. Protein expression was more pronounced in cells during active growth. EGFR were less evident in cultures populated predominantly by melanized cells, indicating that receptor expression became reduced in differentiating cells. Immunocytochemistry confirmed these observations and also showed that EGFR reactivity was predominantly localized in the cell body but absent from dendrites. Addition of TGFalpha to early cultures induced a rapid increase in phosphotyrosine signal of the 170 kDa protein. Longer treatment (24-48 h) increased the intensity of the EGFR signal, suggesting that receptors had been upregulated. However, inclusion of TGFalpha in cultures did not result in an increase in cell numbers when compared to controls. The observations provide evidence of the existence of a receptor-mediated pathway in melanocytes which has transforming potential in vivo.

Growth control of melanoma cells and melanocytes by cytokines

Aberrant proliferation of tumor cells characterizes cancer growth. Investigations of cellular growth control mechanisms have contributed to our understanding of carcinogenesis and to the identification of compounds with specific antitumor activity. Many cytokines have been found to act on melanoma tumors, either produced by the tumor cells themselves or by infiltrating host cells. Purified cytokines allowed direct comparison of the growth response between normal human melanocytes and malignant melanoma cells. The present paper summarizes results of a series of our own experiments not yet published and data from a review of the recent literature. Proliferation of normal human melanocytes is enhanced by several cytokines, including basic fibroblast growth factor (bFGF), melanoma growth stimulatory activity (MGSA), hepatocyte growth factor (HGF), and mast cell growth factor (MGF). Melanoma cells are additionally stimulated by epidermal growth factor (EGF)/transforming growth factor alpha (TGF-alpha) and nerve growth factor (NGF). Tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and interleukin (IL)-6 are all potent inhibitors of melanocyte growth, but they are less effective on melanoma cells or even stimulate their growth. Interferon (IFN)-alpha and IFN-gamma inhibited proliferation of melanoma cells but not of melanocytes, whereas IFN-beta showed antiproliferative effects in both cell types. These findings suggest an alteration in growth control mechanisms during melanocyte transformation and possibly play a role in melanoma pathogenesis.

Alterations in growth phenotype and radiosensitivity after fractionated irradiation of breast carcinoma cells from a single patient

PURPOSE

To investigate growth regulation and radiosensitivity in surviving clonogens after fractionated irradiation.

METHODS AND MATERIALS

Four breast carcinoma cell lines isolated from the primary tumor (21NT, 21PT) and metastases (21MT-1, 21MT-2) of a single patient were exposed to cumulative radiation doses of 30 Gy yielding cell lines designated-IR with respect to their parent. The irradiated lines were then compared to their parent for serum-and growth factor-requirements under defined media conditions, ability to proliferate in soft agar, concentration of TGF-alpha in conditioned medium, and radiosensitivity.

RESULTS

The irradiated lines showed no change in proliferative doubling times under serum- and growth factor-supplemented media conditions. A single line, 21MT-1-IR, acquired a limited ability to proliferate in serum-and growth factor-deplete medium with a day 2-4 doubling time of 44.5 hr. Three lines, 21MT-1-IR, 21MT-2-IR, and 21NT-IR, formed colonies in soft agar in contrast to none of the unirradiated parent lines. There were significant 6-8 fold increases in conditioned media TGF-alpha concentrations for 21MT-2-IR and 21NT-IR cells. The 21MT-1-IR and 21NT-IR cells were significantly less radiosensitive than their respective parent lines. This decrease in radiosensitivity appeared to be at least partially mediated by a released factor as the radiosensitivity of 21MT-1 cells was significantly decreased by pre-incubation with conditioned medium from 21MT-1-IR cells.

CONCLUSION

Radiation-induced changes in growth phenotype vary with respect to clonal origin of the cell line and may influence the radiosensitivity of surviving clonogens after fractionated treatment.

Epidermal growth factor in human breast cancer, endometrial carcinoma and lung cancer. Its relationship to epidermal growth factor receptor, estradiol receptor and tumor TNM

Epidermal growth factor (EGF) and its receptor (EGFR) were measured in 60 breast cancers (BC), 6 benign mammary tumors (BM), 8 samples of normal breast (NB), 6 endometrial carcinomas (EC) and 30 lung cancers (LC). EGF was measured in plasma, saliva and urine from 20 patients with BC, before and after tumor excision, and in 8 patients with metastatic disease. The median EGF in BM and BC was significantly higher (P < 0.05) than in NB. No significant correlation between EGF and EGFR was found in BC. Neither tumor excision nor the spreading of the disease significantly modified the EGF concentrations in biological fluids. In LC there was an inverse relationship between EGF and EGFR (rs = -0.36; P = 0.09), which disappeared in normal lung. It is concluded that EGF may play a role in malignant transformation; however, the weak correlation between EGF and EGFR lessens the importance of EGF in either autocrine or paracrine stimulation of tumor growth.

Transforming growth factor-alpha activity in effusions: comparison of radioimmunoassay and radioreceptorassay

Transforming growth factor-alpha (TGF-alpha) in pleural and peritoneal effusions was assayed by homologous radioimmunoassay (RIA) and radioreceptor assay (RRA) using human placental membrane. Effusions were obtained from 24 patients with and 17 patients without cancer. Most of the effusions were found to contain TGF-alpha by RIA and RRA, but immunoreactive epidermal growth factor (EGF) was not detected. Effusions were chromatographed on Bio-Gel P-60 with several peaks of TGF-alpha activity by both RIA and RRA. A discrepancy in the chromatographic pattern of TGF-alpha between RIA and RRa suggested the existence of EGF-like substances capable of binding to EGF receptors which lack immunoreactivity for EGF or TGF-alpha. The TGF-alpha concentration of the acetic acid-extracted malignant effusions assayed by RRA significantly exceeded the value obtained from benign effusions (17.0 +/- 8.7 vs. 9.2 +/- 6.3 ng/ml; mean +/- SD: p < 0.02). However, the concentrations obtained by RIA did not differ.

Constitutive expression of multiple growth factor genes by melanoma cells but not normal melanocytes

In a panel of metastatic melanoma cell lines we found steady-state mRNA transcripts for multiple growth factors including basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-A, PDGF-B, transforming growth factor (TGF)- beta 1, TGF- alpha, melanoma growth-stimulating activity (MGSA), interleukin (IL)-1 alpha, and IL-1 beta but not insulin-like growth factor (IGF)-1 or IGF-2. Expression of growth factor genes was constitutive because prior to RNA extraction melanoma cells were maintained in a chemically defined culture medium free of exogenous growth factors. Each of four cell lines had an individual pattern of expression of either two, four, five, or seven growth factors; however, all cell lines shared expression of the bFGF gene. Two strains of normal melanocytes expressed TGF- beta 1 but not bFGF, PDGF, TGF- alpha , or MGSA mRNA at detectable levels. We tested growth-modulatory effects of the growth factors most frequently expressed by melanoma cells (bFGF, TGF- alpha, TGF- beta, PDGF). None of these stimulated melanoma cell growth consistently, whereas exogenous, acid-activated TGF- beta inhibited melanoma growth at concentrations greater than 10 ng/ml, suggesting that bioactive TGF- beta may represent a physiologic growth inhibitor. Neither neutralizing antisera to PDGF or TGF- alpha nor a monoclonal antibody to the epidermal growth factor (EGF)-receptor inhibited melanoma cell growth. Our results indicate that multiple growth factors are expressed simultaneously and constitutively by melanoma cells but not normal melanocytes in culture. Expression of bFGF is a common feature underscoring the significance of bFGF as an autocrine factor for melanoma cells as described earlier. Secreted PDGF and TGF- alpha are apparently not involved in or not essential for autocrine growth stimulation of melanoma cells.

Growth factors in melanoma

Human melanoma cells in culture are the source of a wide variety of polypeptide growth factors. Melanoma-derived basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF)-A and PDGF-B chains, transforming growth factor (TGF)-alpha and TGF-beta, interleukin (IL)-1 alpha and IL-1 beta, and melanoma growth stimulatory activity (MGSA) have similar biochemical and functional properties when compared to their counterparts produced by untransformed cells. In contrast to melanoma cells, normal melanocytes, even under optimal growth conditions, express only TGF-beta 1 and MGSA at detectable levels suggesting that production of the other growth factors is a tumor-associated phenomenon. Recent evidence suggests that at least two of the growth factors, bFGF and MGSA, contribute to autocrine growth stimulation of melanoma cells. Whether PDGF, TGF-alpha, IL-1, and TGF-beta act in an autocrine mode is unclear at present. However, these four growth factors are among those secreted by melanoma cells and, therefore, can be expected to interact with normal cells of the tumor stroma in vivo. Such paracrine effects include not only growth modulation in the context of angiogenesis and stroma formation, but also tissue degradation by proteolytic enzymes, the modification of extracellular matrix composition, and expression of adhesion receptors.

Transforming growth factor (TGF)-alpha in human milk

Transforming growth factor (TGF)-alpha and epidermal growth factor (EGF) were measured in human milk by means of homologous radioimmunoassay. As previously reported, EGF concentration in the colostrum was approximately 200 ng/ml and decreased to 50 ng/ml by day 7 postpartum. The value of immunoreactive (IR)-TGF-alpha was 2.2-7.2 ng/ml, much lower than that of EGF. In contrast to EGF, the concentration of IR-TGF-alpha was fairly stable during the 7 postpartum days. There was no relationship between the concentrations of IR-TGF-alpha and IR-EGF, suggesting that the regulatory mechanism in the release of the two growth factors is different. On gel-chromatography using a Sephadex G-50 column, IR-EGF appeared in the fraction corresponding to that of authentic human EGF, while 70%-80% of the IR-TGF-alpha was eluted as a species with a molecular weight greater than that of authentic human TGF-alpha. Although the physiological role of TGF-alpha in milk is not known, it is possible that it is involved in the development of the mammary gland and/or the growth of newborn infants.

Detection of urinary TGF-alpha by HPLC and western blot in patients with melanoma

Transforming growth factor-alpha (TGF-alpha) secretion in the urine may reflect autonomous production by neoplasms. Previous measurements of TGF-alpha in the urine were limited by the large volumes of urine required for detection. Sensitive assays are required to detect TGF-alpha in small urine samples from individual patients with melanoma. An assay which detects ng quantities of immunoreactive TGF-alpha in 10 ml of urine using dialysis, reverse-phase high-performance liquid chromatography (HPLC), and Western blot of the HPLC fractions was used to study the urine from 6 melanoma patients and 6 normal human volunteers. No TGF-alpha was detectable in the first voided urine specimens from the normal volunteers. In contrast, TGF-alpha was detected in the urine specimens of two of three patients with primary melanomas and two of three patients with metastatic melanoma. The sensitivity and reliability of the assay were most affected by methods of urine collection, sample preparation, and storage. TGF-alpha was less often found in randomly voided urine samples from melanoma patients (1 of 3 detectable) as compared to first voided morning urine samples (3 of 3 detectable). This data indicates urinary TGF-alpha assay may be useful in the diagnosis and management of patients with melanoma.

High molecular weight type-alpha transforming growth factor in the urine of patients with surgical bone wound involved in mandibular osteotomy

Activity of transforming growth factors (TGFs) in urine from the patients with surgical bone wound involved in mandibular osteotomy, was examined by the use of NRK-49F indicator cells. The urine was extracted by an acid-ethanol method, fractionated on a Bio-Gel P-100 column or reverse-phase high performance liquid chromatography (HPLC), and analysed for TGF activity. TGF-alpha activity in the Mr 30-27 or 12-10 kDa ranges, which was determined in the HPLC fractions containing TGF activity by dot-blot analysis using antisera to human TGF-alpha (hTGF-alpha) and hEGF, was detected in urine from the patients but not from normal controls. From an analysis of urine samples collected prior to operation and after operation in individual patients, we have shown that there is an intimate relationship between repair of surgical bone wound and the TGF-alpha activity.

A new sandwich enzyme-linked immunosorbent assay (ELISA) for transforming growth factor alpha (TGF alpha) based upon conformational modification by antibody binding

A sandwich-type enzyme-linked immunosorbent assay (ELISA) for human TGF alpha was established utilizing monoclonal and polyclonal anti-synthetic human TGF alpha antibodies with defined epitopes. A polyclonal antibody which was raised in a rabbit and affinity purified by C terminal peptide (hTGF alpha (34-50)) recognized both intact and denatured human TGF alpha. Murine monoclonal antibodies isolated bound only to the denatured form of TGF alpha at the second loop (hTGF alpha (16-33)). However, the rabbit antibody was found to induce a conformation change of intact TGF alpha and the resultant immunocomplex was recognized by monoclonal antibodies. By virtue of this property, the ELISA could detect both native and denatured TGF alpha with the same efficiency with a detection limit of 0.1 ng/ml. Human EGF did not interfere with the ELISA. Production of TGF alpha in several transformed human cell lines was quantitatively examined. Some cell lines were found to secrete TGF alpha, but the production rate was very low, except one melanoma, suggesting that TGF alpha may function only locally in a very limited area in vivo.

Transforming growth factor-alpha and human cancer

Human transforming growth factor-alpha TGF-alpha, a polypeptide growth factor which causes reversible transformation of normal cells, is composed of 50 amino acid residues, has a 30 to 40% amino acid homology to epidermal growth factor (EGF), and binds the EGF receptor. In human cancers, studies are beginning to show that TGF-alpha could serve as a tumor marker and as a marker for the malignant potential of a tumor. Thus far, the types of carcinomas with which abnormal TGF-alpha expression has been associated include liver, gastrointestinal, breast, skin, lung, brain and ovarian cancers. TGF-alpha may play a role in the processes involved with tumor initiation and tumor growth. In cell lines, TGF-alpha has been found to be associated with autocrine and paracrine types of cellular growth initiation and with increased levels of oncogene expression. In summary, the evidence concerning human TGF-alpha are that TGF-alpha could serve as a marker for human cancers and that an understanding of the basic actions of TGF-alpha could help to explain the self-sustaining nature of tumors.

Determination of transforming growth factor activity in effusions from cancer patients

Transforming growth factors (TGF) are polypeptides that stimulate anchorage-independent growth of various nontransformed cells in vitro. Transforming growth factors have been found in tumor extracts and in the urine of cancer patients. The specific questions of our study were whether TGF activity can be detected in malignant effusions, how different assays for TGF correlate with each other, and how assays for TGF correlate with soft agar tumor colony formation as measured by the human tumor cloning assay (HTCA). The TGF activity was measured by a normal rat kidney transformation assay (NRKA), a 125I-EGF radioreceptor assay (RRA), and a radioimmunoassay (RIA) for TGF-alpha. Cells from effusions were cytologically examined and plated in the HTCA. A total of 104 effusions from cancer patients and 17 effusions from non-cancer patients was tested. Transforming growth factor activity was detected in some specimens. Only the TGF-alpha RIA and the HTCA showed significant differences between cancer and noncancer patients. Immunoreactive TGF-alpha was measurable in some cases by RIA even when cytologic testing failed to detect malignant cells. Spearman correlations between assays indicated that RIA results correlate significantly with all other assays. It is concluded that TGF-alpha activity might be important for in vitro colony formation of human tumor cells.

Cerebral metastases from malignant melanoma

Six hundred and fifty-two patients with histologically proven primary malignant melanoma have been followed by the London Regional Cancer Centre from 1960 to 1985. Neurological signs and symptoms secondary to metastases to the brain developed in fifty-five patients (8.4%). The median age was 49 years; 71% were male and 29% female. Multiple lesions were found in 61% and a single metastasis in 39%. The most common site for the primary lesion was the trunk in males (44%) and the lower limb in females (37%). Six month survival for patients with a single metastasis was 58% if surgical excision was possible and 25% of these patients survived greater than two years. In patients with multiple metastases that received radiotherapy, survival times of greater than six months were found in 12% of the patients. Patients with a single metastasis appear to benefit by being managed by surgical removal of the lesion.

Transforming growth factors in urine from patients with primary brain tumors

Urine specimens obtained from 19 patients with primary brain tumors were examined for the activity of transforming growth factors (TGF's). Urine was assayed for TGF's by soft agar colony formation and iodine-125 (125I)-epidermal growth factor (EGF)-binding competition. Two nontransformed cell lines, clonal NRK49F and BALB/3T3 A31-1-1 cells, were used as indicator cells for the soft agar colony assay, while EGF receptor-rich A431 cells were used for 125I-EGF-binding competition assay. Urine samples were dialyzed against acetic acid, then lyophilized, prepared with gel-permeation chromatography, and assayed. All 19 patients and a control group of healthy individuals showed high levels of alpha-type TGF's with low molecular weight (4 to 8 kD) in all urine samples. In addition, alpha-type TGF's of high molecular weight (20 to 50 kD) were detected at high levels in urine from all 10 patients with high-grade astrocytoma; at intermediate levels in urine from one of two patients with low-grade astrocytoma and from two of four patients with meningioma; and at low levels in urine from one of two patients with low-grade astrocytoma, from two of four patients with meningioma, from one patient with oligodendroglioma, from two patients with neurinoma, and from all healthy control individuals. The high level of alpha-type TGF's with high molecular weight detected in urine from patients with high-grade astrocytoma could be useful as a tumor marker.

Characteristics of cultured human melanocytes from different stages of tumor progression

Based on the clinicopathological delineation of distinct steps of tumor progression in the melanocytic system, the in vitro behavior of melanocytes with increasing malignant potential has been investigated. Tumor progression in melanocytes is characterized by an increasing growth autonomy and decreased requirement but enhanced utilization of exogenously provided polypetide growth factors (EGF, IGF-I). The endogenous production of growth factors such as alpha-TGF, PDGF, and bFGF by metastatic melanoma cells might contribute to their independence from exogenously provided factors. Although expression of some melanoma-associated antigens in vivo is detectable only on malignant cells, propagation of normal melanocytes in tissue culture leads to expression of the majority of these antigens. Many of these antigens can be grouped into functionally defined categories, including growth factor receptors, extracellular matrix proteins, and cell-substrate interacting antigens. One cell-substrate interacting antigen, the GD2/GD3 ganglioside, appears to play a critical role in the metastatic process of melanoma cells. The successful propagation and characterization of melanocytic cells of all stages of tumor progression in tissue culture provide a unique human experimental model for the study of mechanisms of malignant transformation.

Transforming growth factor type beta in normal human urine

TGF beta has been identified in normal human urine specimens from five individuals studied for five consecutive days. The peptide was extracted from urine using Sepralyte C1 beads. Detectable levels of [125I]TGF beta competing activity as measured by radioreceptor assay was found in about half of the specimens studied. The protein isolated from urine using C1 Sepralyte beads was further purified using Biogel P-60 column chromatography. Fractions were tested for TGF beta and EGF competing activity using radioreceptor assays. TGF beta and EGF extracted from urine are clearly separated by column chromatography. Two distinct EGF peaks and a single TGF beta peak were observed. Fractions having [125I]TGF beta competing activity were pooled and further purified using reverse-phase HPLC. HPLC fractions having [125I]TGF beta competing activity were tested for bioactivity using a soft agar assay. The fractions were capable of stimulating soft agar growth of AKR-2B (clone 84A) cells and cross reacted with a TGF beta antibody in a radioimmunoassay. The presence of TGF beta in normal human urine was also demonstrated by immunoblotting. These results also suggest that C1 bead extraction of urine specimens can be used as a rapid first step in purification of TGF beta.

Urinary TGFs1 in neoplasia: immunoreactive TGF-alpha in the urine of patients with disseminated breast carcinoma

A tumor-associated growth factor was identified in a 22-liter pool of urine from patients with disseminated breast cancer using an isolation scheme which separates transforming growth factor-alpha (TGF-alpha) from the high level of human epidermal growth factor (hEGF) normally present in urine. Concentration of urinary proteins by adsorption onto methyl bonded microparticulate silica, selective elution by acetonitrile, and subsequent gel permeation, cation exchange, and high performance liquid chromatography, resolved an EGF-related growth factor which generated a competitive binding curve similar to that of synthetic rat TGF-alpha in radioimmunoassay. A 26-liter pool of urine from normal subjects, evaluated in the same manner as a part of another study, did not contain measureable quantities of this factor.

Relative responsiveness of cultured human epidermal melanocytes and melanoma cells to selected mitogens

Early cellular events in the malignant transformation of melanocytes to melanoma are virtually unknown. In vitro investigation of this phenomenon has been hampered by the fastidious nature of the human epidermal melanocyte, which has proven difficult to cultivate. The present study compares responsiveness of cultured human epidermal melanocytes and established melanoma cell lines to serum, cholera toxin, and melanocyte growth factor (MGF), three established melanocyte mitogens. Four of four established human melanoma lines were substantially stimulated by fetal bovine serum, as were newborn foreskin-derived epidermal melanocytes. In contrast, none of the four melanoma lines responded to hypothalamic preparations containing MGF that consistently produced an approximately 30-fold increase in newborn melanocyte cell yield over a 2-week period. Cholera toxin, required for successful establishment of primary melanocyte cultures, had small and variable effects on the melanoma lines, with slight stimulation in one case, moderate inhibition in another, and essentially no effect in two others. These data suggest that transformation of epidermal melanocytes to melanoma often involves at least one phenotypic change resulting in escape from MGF regulation and another associated with insensitivity to cyclic AMP modulation; while at least some of the pathways conferring serum dependence are unaltered. Improved culture systems for the human epidermal melanocyte should facilitate further studies into the mechanism of its malignant conversion and may provide useful insights for the prevention and treatment of human melanoma.

Transformation-related growth factors and their receptors

Cellular transformation may be accomplished in vitro and in vivo through the concerted action of growth factors and oncogenes. This association has demonstrated that malignant growth results from aberrations in growth factor-signal transduction pathways that normally operate to control proliferation. Activation of genes that code for growth factors and/or their receptors provides tumor cells with potential mechanisms to maintain their proliferative state. Tumor cells have been shown to produce endogenous substances that augment their growth (autocrine stimulation), as well as responding to exogenous substances (paracrine stimulation). With solid tumor cells these responses have been shown to involve aberrant expression of growth factor and/or receptor genes. The study of the interrelationship of these various growth regulatory molecules is important not only in the identification of gene products essential to cellular proliferation, but also in providing clues as to what forces are driving tumor cell growth.