Essential viral and cellular zinc and iron containing metalloproteins as targets for novel antiviral and anticancer agents: implications for prevention and therapy of viral diseases and cancer.

In this review the authors summarize the experimental data on the role of a selected group of metalloproteins, particularly viral (v) and cellular (c) zinc finger proteins (ZFP) and iron containing proteins which are involved in cell proliferation, neovascularization, apoptosis, and viral infection. Furthermore, this review summarizes the data embracing the hypothesis that disruption of certain metalloproteins by novel pharmacological agents is a key factor in controlling viral and proliferative diseases. The primary goal of this review is to show the potential therapeutic applications of ZFP disrupting agents, zinc chelators and iron chelators in the control of viral diseases and cancer. It is known that zinc or iron deficiency, resulting from exposure of culture cells to membrane-permeable Zn2+ or Fe(2+)-chelators, can induced apoptosis in virally transformed cells while normal cells remain unaffected under these conditions. Apoptosis is possibly due to simultaneous inactivation of vZFP, cZFP, and/or iron containing proteins, which are essential for maintenance of cellular and viral structure and which are activated in virally transformed cells. New insights concerning apoptosis, viral metalloproteins, and novel antiviral agents will also be reviewed. From the evidence reviewed, one can infer that development of a variety of drugs that control or neutralize vZFP may lead to a new therapeutic approach directed at controlling and preventing a wide spectrum of viral diseases and cancer. Furthermore, the results suggest that these agents may be useful to prevent transmission of viral diseases. Finally, this review not only points out the limits of our understanding of this system, but also directs scientists to opportunities for future research.

Differential expression of metallopanstimulin/S27 ribosomal protein in hepatic regeneration and neoplasia.

We have previously shown that human metallopanstimulin-1 (MPS-1) is a ubiquitous 9.4-kd multifunctional ribosomal S27/nuclear "zinc finger" protein that is expressed at high levels in a wide variety of actively proliferating cells and tumor tissues. In this study, we examined the expression of MPS-1 in chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Tissue samples were obtained at the time of tumor resection, needle biopsy, or liver transplantation. MPS- 1 was studied by immunohistochemistry by use of specific antibodies to the N-terminus of MPS-1 in a biotin/streptavidin-amplified system. In chronic hepatitis, hepatocytes had very weak MPS-1 immunostaining. In contrast, hepatocytes in regenerating cirrhotic nodules stained strongly for MPS-1. In well-differentiated hepatocellular carcinoma, MPS-1 presence was intense at the periphery of the malignant nodule. In poorly differentiated hepatocellular carcinoma, MPS-1 presence was notably intense in malignant hepatocytes invading the septal tissues, in close contact with neovascular structures. These results suggest that MPS-1 may be involved in both progression toward malignancy in regenerating cirrhotic nodules and in subsequent steps of hepatocarcinogenesis.

Effects of human recombinant erythropoietin on differentiation and distribution of erythroid progenitor cells on murine medullary and splenic erythropoiesis during hypoxia and post-hypoxia.

Hemopoietic cells, the extracellular matrix, growth factors and the microenvironment are involved in the regulation of hemopoiesis. Although the regulation of erythropoiesis is well understood at the cellular level in vivo and in vitro, the role of hemopoietic sites of erythroid progenitors production has not been well defined in both steady state conditions and in stress erythropoiesis. In this study we examined the qualitative erythroid differentiation and quantitative changes of the erythroid progenitors in different erythropoietic organs during erythropoiesis of stress in a hypoxia-induced polycythemia and post-hypoxic changes in a mice model. Chronic intermittent exposure to hypobaric hypoxia induced polycythemia in mice and the post-hypoxic period was characterized by total suppression of erythropoiesis. The number and distribution in hemopoietic sites of Immature Erythroid Burst (BFU-EI), Mature Erythroid Burst (BFU-EM) and Erythroid Colony Forming Units (CFU-E) was evaluated in bone marrow and spleen of hypoxic and post-hypoxic mice after removal from the chamber. The number of BFU-EI and CFU-E, was evaluated in both femoral bone marrow and spleen of ex-hypoxic polycythemic mice, at two times intervals after the end of hypoxia. We found that in both bone marrow and spleen, the kinetics of the CFU-E pool was characterized by a sharp fall from above normal to lower than normal levels. BFU-EM increased from normal to higher than normal levels. These results have been correlated with both erythropoietin (EPO) and the erythropoietic activity. The results show that EPO levels largely control both the differentiation and the amplification of the CFU-E pool and they suggest that EPO may acts as a "survival factor" at the CFU-E level and/or increase the flow of cells from BFU-E to CFU-E. After the termination of the period of hypoxia and during post-hypoxia there was a reduction in EPO production which subsequently caused a depletion of the CFU-E population, indicating that the size of the CFU-E pool is EPO-dependent. After the injection of 1U of recombinant human erythropoietin (rHuEPO) the size of that pool was increased and the pool of BFU-EI was decreased. It is noteworthy that our studies show that the spleen functions as a large reservoir of erythroid precursors for hypoxia-induced stress erythropoiesis.

Antiviral, cytotoxic and apoptotic activities of picolinic acid on human immunodeficiency virus-1 and human herpes simplex virus-2 infected cells.

The antiviral, cytotoxic and apoptotic effects of picolinic acid against human immunodeficiency virus-1 (HIV-1) and human herpes simplex virus-2 (HSV-2) infected cells were evaluated in cultured cells using in vitro assays. Picolinic acid was tested at several concentrations (from 0.15 to 3 mM) against one input dilution of the viruses to determine if the agent had any antiviral activity against HIV-1 or HSV-2. The results showed that picolinic acid at 1.5 mM (185 ug/mL) and 3 mM (369 ug/mL) was active against HIV-1 and HSV-2-infected cells, causing cytotoxicity which resulted in apoptosis and lack of viral replication. In parallel control experiments with non-infected cells, picolinic acid also caused cytotoxicity and apoptosis, which was more prominent at 3 mM than at 1.5 mM. Thus, infected cells appear to be slightly more sensitive to the cytotoxic and apoptotic effects of picolinic acid. The overlapping of the antiviral profile with the cytotoxic profile of picolinic acid indicates that, in vitro, the most likely sequence of events is that picolinic acid initially causes cytotoxicity which in turn results in apoptosis of cells infected with HIV-1 or HSV-2 and thus reduces the amount of viral replication.

Molecular interactions of cancer and age.

The authors believe that the aging process--the loss of youthful resilience--is caused by the decline of many hormones. By restoring these hormone levels, the decay associated with old age can be eliminated and in some cases, perhaps reversed. The hormones that naturally occur in the body should be replenished through a medically sound regimen. The hormones must work together. The data indicate that aging occurs at two levels: systemically and cellularly. Systemic controls regulate the rates of intracellular enzymatic processes that accelerate to protect against aging.

Overexpression of MPS antigens by squamous cell carcinomas of the head and neck: immunohistochemical and serological correlation with FDG positron emission tomography.

Survival from advanced primary or recurrent Squamous Cell Carcinoma (SCC) of the head and neck (H&N) is poor. More accurate detection of primary tumors and recurrence may provide ways to improve survival. No standard serum tumor marker is routinely used for surveillance of SCC-H&N. In this paper, we evaluated the performance characteristics of the MPS-H tumor marker test for the quantitative measurement of "MPS-H" heat-generated immunoreactive proteins and assessed the clinical utility of this marker in the detection and monitoring of SCC-H&N. In approximately 92% of the subjects having no evidence of SCC-H&N, the MPS-H levels were lower than 15 ng/mL. In 76% of patients having SCC-H&N at various stages (T1-T4), the MPS-H level was > 15 ng/mL (range: 20-200 ng/mL). In addition, we found a statistically significant correlation between PET positive cases and high MPS-H serum levels in SCC-H&N patients with recurrent disease. These results suggest that MPS-H may provide an initial screening test that would allow for selective PET imaging in these patients. Furthermore, we found that there was greater expression of MPS-1 in tumors of higher histological grades. Thus, in tumors with more histological aggressiveness there is more MPS-1, indicating the potential usefulness of this marker in prognosis for SSC-H&N. Considering the immunohistochemical, serological, and FDG-PET data presented here, and the compelling need to expedite the early diagnosis of primary and recurrent epithelial malignancies of the head and neck, we are further evaluating the system of MPS antigens in a large patient population as a tool for the early serologic and histologic diagnosis of SCC-H&N.

Differential expression of metallopanstimulin/S27 ribosomal protein in melanocytic lesions of the skin.

We have previously shown that human metallopanstimulin (MPS-1) is a ubiquitous 9.4-kDa multifunctional ribosomal S27/nuclear "zinc finger" protein which is expressed at high levels in a wide variety of cultured proliferating cells and tumor tissues, including melanoma. In the present study, we have examined the expression of the MPS-1 protein in various types of human benign and malignant melanocytic lesions of the skin. The expression of the MPS-1 protein was studied by immunohistochemistry using specific anti-MPS-1 antibodies. We found that in benign nevi, the staining is weak and in a gradient; most often, only type A melanocytes stain positive. The B and particularly the C types are negative. Remarkably, congenital nevi show a similar gradient staining of regular benign nevi, but in addition one example showed intensely positive dermal nodules adjacent to areas of negative melanocytes. In melanomas, the staining patterns for MPS-1 are more complex. While some melanomas stain evenly and intensely positive, others have remarkably variable expression of MPS-1. The scattered melanocytes migrating to the upper layers of the epidermis are usually intensely positive. In summary, benign lesions stain in an orderly pattern with staining gradients that correlate with the cellular differentiation of the nevi. Malignant melanomas have an erratic, often intense staining that also correlates with the disorderly growth of these neoplasms. These differential results indicate that the MPS-1 antigen is a useful marker for melanocytic lesions at the immunohistochemical level.

Expression of metallopanstimulin and oncogenesis in human prostatic carcinoma.

BACKGROUND: We have previously shown that human metallopanstimulin (MPS-1) is a 9.4-kDa multifunctional ribosomal S27/nuclear "zinc finger" protein which is expressed in a wide variety of actively proliferating cells and tumor tissues. Furthermore, we have shown that detection of MPS-N immunoreactive material in sera corresponding to the NH2 terminus of MPS-1 provides a method for determining the presence of certain types of abnormal proliferative conditions and/or active oncogenic processes in patients. In this study, we investigated MPS-N and MPS-N-like antigens present in the blood of patients with prostatic carcinoma (PC) and their relationship to the clinical status of patients with PC. METHODS: The presence of MPS-N immunoreactive material was determined using a sensitive and specific radioimmunoassay (RIA) which has been developed to measure circulating levels of MPS-N antigen(s). In addition, MPS-N levels were compared to the primary bio-marker used in PC patient management, Prostatic Specific Antigen (PSA). RESULTS: MPS-N concentrations were determined in the blood of 107 males having no evidence of PC, and in 126 patients diagnosed with PC. In patients, not having PC the MPS-N levels were lower than 10 ng/mL. In untreated patients having PC stages T1/T2, the MPS-N level range was 10-30 ng/mL; in stages T3/T4 the MPS-N level range was 30-50 ng/mL; and in stage Mlb (distant metastasis to the bones) the MPS-N levels were extremely high (> 50 ng/mL). In Mlb patients that did not respond to therapy, the MPS-N levels remained very high (> 50 ng/mL). In Mlb patients that went into remission after treatment, the MPS-N levels were dramatically reduced. In addition, a comparison of the test properties of MPS-N and PSA for prostate cancer were evaluated in a total of 231 patients. In both the low and high value range, both MPS-N and PSA appear to be equally effective in modifying the probability of the target condition-prostatic cancer. CONCLUSIONS: These findings show that (1) in untreated PC patients, the increase in serum MPS-N correlated with the stage of the disease; (2) MPS-N tumor marker predicted the degree of aggressiveness of tumor growth and response to therapy. In summary, despite the uncertainties of the relative contributions of the molecules being measured in cancer patients (authentic MPS-1, and MPS-N-like protein sequences), the MPS-N test is a pragmatic test that correlates well with active prostatic malignancy.

Metallopanstimulin is overexpressed in a patient with colonic carcinoma.

BACKGROUND: Human metallopanstimulin (MPS-1) is a 9.4-kDa multifunctional ribosomal S27 nuclear "zinc finger" protein which is expressed in a wide variety of actively proliferating cells and tumor tissues. In this paper, we present a case of overexpression of MPS-1 in colon cancer tissues of a seventeen year old male. METHODS: Biopsies at the anastomosis and adjacent normal colonic mucosa were obtained by colonoscopy twelve months after right hemicolectomy for an ascending colon well differentiated adenocarcinoma. Immunohistochemical localization of MPS-1 protein was performed by using specific anti-MPS-1 antibodies directed against the N-terminal region of this protein. RESULTS: Immunohistochemistry demostrated an overexpression of MPS-1 in colonic mucosa crypts in the samples obtained at the anastomosis. In contrast, no expression of MPS-1 was observed in the adjacent normal mucosa. Histopathology performed with hematoxilin and eosin staining revealed focal crypt distortion and proliferation, but no carcinoma. CONCLUSIONS: In this case, the overexpression of MPS-1 was a more definitive evidence of malignant transformation than histology, as demonstrated by the clinical course of the disease. The results support the hypothesis that increased levels of tissue MPS-1 may correlate with a more aggressive behavior of colon malignancy.

Metallopanstimulin as a novel tumor marker in sera of patients with various types of common cancers: implications for prevention and therapy.

Metallopanstimulin (MPS) is a 9.5-kDal subunit "zinc finger" protein which is expressed in a wide variety of actively proliferating cells and tumor tissues (J. Biol. Chem. 268:21198-21204, 1993; Cell Growth & Diff. 5:811-825, 1994). A sensitive and specific radioimmunoassay (RIA) has been developed to measure circulating levels of MPS and MPS-like proteins. The RIA was evaluated for its ability to detect accurately elevations of MPS-immunoreactive material in the blood of patients with various types of neoplastic diseases. MPS concentrations were determined in the blood of 147 healthy subjects having no evidence of neoplastic disease, in 260 patients with nonmalignant diseases, and in 225 patients diagnosed with various types of cancer such as prostate, colorectal, lung, head and neck (epithelial malignancies), neuroendocrine, central nervous system, etc. Elevated MPS levels identified patients with neoplasias with greater than 90% confidence. In patients, not having neoplastic disease the MPS levels were lower than 10 ng/mL (82% of the population). In untreated patients with cancer, the MPS level range was 20-50 ng/mL and in stage M1b (metastasis to the bones) the MPS levels were extremely high (100 to 1000 ng/mL). In M1b patients that did not respond to therapy, the MPS levels remained very high ( > 100 ng/mL). In M1b patients that went into remission after treatment, the MPS levels were reduced. The MPS test may be useful as an aid in: 1) the early detection of a wide variety of neoplastic conditions and 2) the prognosis and management of cancer patients by following the changes in the concentrations of MPS in sera. Moreover, the results suggest that the combined use of the MPS test with other currently available tumor maker tests may significantly improve the chances of identifying a large proportion of active oncogenic processes by serodiagnosis.

Metallopanstimulin gene product produced in a baculovirus expression system is a nuclear phosphoprotein that binds to DNA.

The protein product of the human Metallopanstimulin (MPS-1) gene was produced in the insect cell line Spodoptera frugiperda (Sf9) using the baculovirus expression vector system Autographa californica nuclear polyhedrosis virus (AcNPV). When a cloned MPS-1 complementary DNA sequence was inserted into the AcNPV viral genome downstream from the promoter of the polyhedrin gene, a polypeptide with an apparent molecular weight of approximately 10,000 was observed in extracts of infected Sf9 cells. This protein was not detected in Sf9 cells infected with AcNPV-MPS-1-Del, a vector in which the MPS-1 gene was deleted. The MPS-1 protein was produced at high levels in this host-vector system (congruent to 12% of total labeled soluble protein). Characterization of the MPS-1 protein extracted from Sf9 infected cells showed that it: binds zinc ions specifically; is phosphorylated; accumulates in the nucleus; is tightly bound to the nucleus; and binds to calf thymus DNA-cellulose. The MPS-1 protein constitutes one of the major proteins in the nuclear fraction of Sf9 cells and can be purified from this source to near homogeneity by a two-step procedure composed of high-performance liquid chromatography and gel electrophoresis. Antibodies were raised against selected peptide sequences of the MPS-1 protein and used to detect MPS-1 in insect cells and in various cultured mammalian cell types. Western analysis demonstrated that the baculovirus-generated protein had electrophoretic and immunological properties equivalent to those of MPS-1 spontaneously expressed in various human mammalian cell lines. Finally, recombinant MPS-1 generated a specific protein-DNA complex with a duplex oligomer containing a cyclic AMP-responsive element, as assessed by gel mobility shift assays. These results support the hypothesis that the MPS-1 protein may act, at least in part, by interacting with genes possessing the cyclic AMP-responsive element sequence.

Expression of metallopanstimulin in condylomata acuminata of the female anogenital region induced by papilloma virus.

We have identified by cDNA cloning a gene, denoted MPS-1, that is activated in cultured human transformed cells by growth factors. The MPS-1 gene contains one zinc finger domain similar to those present in the C4 family of DNA binding proteins. In this study, the expression of MPS-1 mRNA and protein were examined in HPV-induced human condylomata acuminata. Initially, we detected the presence of MPS-1 mRNA by message amplification phenotyping in all condylomata tissues examined. Subsequently, the cellular distribution and abundance of MPS-1 mRNA was studied by in situ hybridization with specific MPS-1 DNA and RNA probes. We found that MPS-1 mRNA is expressed at high levels in the cytoplasm of condylomata cells. In contrast, the MPS-1 mRNA is expressed at low levels in nonneoplastic tissues. Moreover, antibodies were raised against the predicted N-terminal sequence of the MPS-1 protein and used to detect MPS-1 in condylomata cells. MPS-1 immunoreactivity was detected in the cytoplasm and/or the perinuclear regions of condylomata cells, with marked staining in areas of active proliferation. In distinction, MPS-1 immunoreactivity was very weak in normal epithelial cells. The results support the contention that the MPS-1 protein may be a potentially important mediator of proliferative responses induced by HPV.

A growth factor-inducible gene encodes a novel nuclear protein with zinc finger structure.

Growth factors rapidly induce numerous genes that encode regulatory proteins, many of which have been identified by cDNA cloning. In this study, differential hybridization was used to screen a cDNA library constructed from human mammary carcinoma MDA-468 cells that were stimulated with transforming growth factor beta-1 (TGF-beta 1) in the presence of cycloheximide. One of the cDNA clones that was induced by TGF-beta 1 was found to have a nucleotide sequence that predicts a 9,450-Da protein with homology to regulatory DNA-binding proteins. This clone was designated metallopan-stimulin-1 (MPS-1) because it encodes a metalloprotein whose mRNA is expressed in a wide variety of actively proliferating cells and tumor tissues. MPS-1 protein contains one "zinc finger" domain of the C4 type, similar to those present in proteins of the steroid/thyroid hormone receptor superfamily and other DNA-binding proteins. The mRNA for MPS-1 was induced in MDA-468 cells by fetal calf serum, TGF-beta 1, TGF-beta 2, and cAMP analogues. The MPS-1 gene is expressed at relatively high levels in several human carcinoma cell lines, particularly those derived from ectodermal layers, and at higher levels in melanomas (ontogenically of neural origin). In contrast, the MPS-1 mRNA is expressed at low levels in normal WI-38 human lung diploid fibroblasts in culture. We hypothesize that MPS-1 protein may play a role as a potentially important mediator of cellular proliferative responses to various growth factors and other environmental signals.

Epidermal growth factor stimulates thyrotropin secretion in the rat.

The present work studied the effects of epidermal growth factor (EGF) on the release of thyrotropin (TSH) and prolactin (PRL) from perifused pituitary glands of 200-gram male Wistar rats. Each pituitary gland, cut into halves, was placed in a chamber of a perifusion system connected to a peristaltic pump which conveyed the perifusion medium (Medium 199, pH 7.3, Gibco, USA) from a reservoir to a chamber at a flow rate of 100 microliters/min. Each tightly closed chamber contained one pituitary gland and 600 microliters medium and it was placed in a water bath at 37 degrees C throughout the experiment. One milliliter samples of effluent were collected every 10 min for 60 min to obtain baseline values of TSH and PRL. Thereafter, TSH-releasing hormone (TRH) 10(-8) M or EGF (10(-11), 10(-10), 10(-9) or 10(-8) M) were added to individual chambers and the 10-min sampling of effluent continued for 60 min. EGF 10(-11) M elicited no TSH response, but 10(-10) and 10(-9) M doses induced significant increases in TSH secretion (p < 0.01) with a peak at 10 min after addition of EGF. In another experiment, EGF 10(-8) M or TRH 10(-8) M significantly elevated TSH secretion (p < 0.01). However, TRH, but not EGF, stimulated PRL secretion (p < 0.01). In the in vivo studies, the intravenous administration of EGF 10(-5) M or TRH 10(-5) M both induced significant elevation of TSH release at 10 min after the injection (p < 0.02 for EGF and p < 0.01 for TRH).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytotoxic activity of fusaric acid on human adenocarcinoma cells in tissue culture.

When cultured human normal WI-38 fibroblasts were exposed to 500 microM fusaric acid (5-butylpicolinic acid), cell proliferation ceases. The majority of the WI-38 cells remained in a quiescent G1(G0) state and viable for approximately 30 to 48 h. The effect of fusaric acid on WI-38 cell growth was slowly reversible after removal of the agent from the culture media. In contrast, within 24 h of exposure to 500 microM fusaric acid, most of the human colon adenocarcinoma LoVo cells were blocked at random in the cell cycle and approximately 80% of the cells were dead after 30 h. Three additional human colorectal adenocarcinoma cell lines, denoted SW48, SW480, and SW742, were also sensitive to the inhibitory and cytotoxic effects of fusaric acid. Of all the cell lines tested, the human mammary adenocarcinoma cell line MDA-MB-468 was the most sensitive to the growth inhibitory and cytotoxic effects of fusaric acid. Further experiments with MDA-MB-468 cells demonstrated that fusaric acid is a potent inhibitor of DNA synthesis. Fusaric acid also inhibited the growth of human epidermoid carcinoma KB cells and showed cytotoxic actions for this cell line but its effects on cell viability were not as pronounced. The results presented here indicate that fusaric acid has potent anti-proliferative activity in vitro on various normal and cancer cell lines and suggest that it exhibits some cytotoxic specificity for growing and confluent colorectal adenocarcinoma and mammary adenocarcinoma cell lines.

Expression of transforming growth factor alpha mRNA in benign and malignant tissues derived from gynecologic patients with various proliferative conditions.

Growth factors are polypeptides involved in the regulation of normal and malignant cell growth. Transforming growth factor alpha (TGF alpha) is one of such protein growth factors that plays an important role in the regulation of mammalian cell growth. In this study, the expression of TGF alpha mRNA was studied in tissue specimens obtained at the time of surgery from patients with benign and malignant gynecologic proliferative conditions. To analyze TGF alpha mRNA expression we utilized the highly sensitive technique denoted Message Amplification Phenotyping which can detect mRNA in single cells. This technique consists of isolating RNA, reverse transcription of total cellular RNA to produce copy DNA, followed by enzymatic amplification of TGF alpha cDNA fragments using specific TGF alpha primers and polymerase chain reaction. The results showed significant levels to TGF alpha mRNA expression in vulvar (100% of the cases positive), cervical (66% positive), and endometrial (66% positive) carcinomas. Moreover, vulvar condylomas produced by human papilloma virus (HPV) showed the highest levels of TGF alpha mRNA expression of all the pathological tissues examined. In contrast, vulvar melanoma, fibrocystic disease of the breast, and certain ovarian tumors showed undetectable TGF alpha mRNA expression. Normal mesodermal tissues such as myometrium, abdominal rectus muscle, and fallopian tubes were negative for TGF alpha mRNA expression. However, TGF alpha mRNA was present in normal cervix and in normal endometrium. The results showed that TGF alpha mRNA expression is frequently associated with various malignant tumors and HPV-induced lesions of epithelial origin, suggesting that TGF alpha mRNA protein product may be a contributory factor in the progression of these pathological tissue alterations. Finally, TGF alpha mRNA expression was not restricted to malignant cells, suggesting that the TGF alpha mRNA protein product may function as a mitogen in the normal human epithelial tissues examined.

Modulation of EGF receptor protooncogene expression by growth factors and hormones in human breast carcinoma cells.

In this review I summarize the experimental data in favor of the notion that control of epidermal growth factor (EGF) receptor (R) and/or c-erbB-2 protooncogene expression by specific autocrine growth factors and certain classical endocrine hormones serves as a transducer of extracellular signals that ultimately lead to growth responses in breast carcinoma cells. I summarize some new results on the role of epidermal growth factor (EGF), transforming growth factor (TGF) alpha, and TGF beta in the control of EGF-R protooncogene expression in human breast carcinoma cells. Furthermore, the data embracing the hypothesis that the growth actions of hormone receptors that are homologous to the v-erbA oncogene (estrogens, progesterone, thyroid hormones, retinoic acid, and vitamin D) are mediated, in part, by modulating EGF-R and/or c-erbB-2 protooncogene transcription are reviewed. Finally, I develop the theme that cooperation of certain c-erb-A-related, c-erbB-2 and/or EGF-R gene products contribute to the uncontrolled growth of human mammary carcinoma cells. From the evidence reviewed, one can infer that elucidation of the molecular control of EGF-R/c-erbB-2 gene expression by c-erbA-related gene products may lead to both a better understanding of breast carcinogenesis and a new therapeutic approach directed at controlling the transcriptional responses of EGF-R/c-erbB-2 genes.

Modulation of transforming growth factor alpha-dependent expression of epidermal growth factor receptor gene by transforming growth factor beta, triiodothyronine, and retinoic acid.

We have investigated the actions of transforming growth factor (TGF) type alpha on epidermal growth factor (EGF) receptor mRNA expression in MDA-468 human mammary carcinoma cells in serum-free media. We found that exposure of MDA-468 cells to TGF alpha results in elevated levels of EGF receptor mRNA. This increase in mRNA accumulation showed time and dose dependence. Addition of TGF beta 1 enhanced the accumulation of EGF receptor mRNA induced by TGF alpha in a time- and dose-dependent manner. We also found that triiodothyronine at physiological concentrations exerts synergistic control on the action of TGF alpha alone, or in association with TGF beta 1, on EGF receptor mRNA expression. Similarly, retinoic acid treatment also enhanced in a time- and dose-dependent manner the TGF alpha-dependent response of EGF receptor mRNA and acted synergistically with TGF beta 1. The results described here suggest that optimum regulation of EGF receptor gene expression by TGF alpha is a complex process involving synergistic interactions with heterologous growth factors and hormones.

Transcriptional regulation of proto-oncogene expression by epidermal growth factor, transforming growth factor beta 1, and triiodothyronine in MDA-468 cells.

We have examined the epidermal growth factor (EGF) dependence of the transcription of different proto-oncogenes, using cultured human mammary carcinoma MDA-468 cells and a nuclear run-on transcription assay. We found that the stimulation of MDA-468 cells with EGF regulates moderately and to different extents the transcription of the EGF-receptor(R) and c-erbB-2 proto-oncogenes. In contrast, the transcription of other proto-oncogenes, including c-myc, c-H-ras, and c-fps, was unchanged. Furthermore, we provide evidence that transforming growth factor beta 1 (TGF-beta 1) selectively and to different degrees modulates the EGF-dependent transcription of EGF-R and c-erbB-2 genes. In this study, we also discovered that T3 (triiodothyronine) exerts synergistic control on the action of EGF alone or in association with TGF-beta 1, on EGF-R and c-erbB-2 gene transcription. Moreover, we established that within 6 h after the addition of EGF, cytoplasmic EGF-R mRNA levels are increased several-fold and that this accumulation is enhanced by the presence of TGF-beta 1 and/or T3. The results described here are consistent with the hypothesis that a complex program of cooperative interactions among EGF-, TGF-beta 1-, and T3-generated signals at the transcriptional level may mediate, at least in part, the combined actions of EGF, TGF-beta 1, and T3 in target cells.