Workgroup 4: spontaneous prostate carcinoma in dogs and nonhuman primates.
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Aging↗
Biomedical subjects
R Radinsky
Publications and source records attributed to R Radinsky.
Preferential activation of the epidermal growth factor receptor in human colon carcinoma liver metastases in nude mice.
Increased epidermal growth factor receptor (EGF-R) gene expression and functional protein levels correlate with the metastatic potential of human colon carcinoma (HCC) cells in nude mice. The purpose of this study was to determine whether the production of liver metastases by HCC cells depends on the EGF-R activation status and whether different organ microenvironments influence this activation. Using two independent monoclonal antibodies specific for the activated (i.e., tyrosine-phosphorylated) EGF-R, increased immunoreactivity was observed in HCC cells growing as metastatic lesions in the livers of athymic nude mice. Staining was observed throughout these lesions, both peripherally and centrally. In contrast, little or no immunoreactivity for activated EGF-R was observed in primary tumors growing orthotopically in the cecum or ectopically in the subcutis of nude mice. Immunohistochemistry for total EGF-R levels (irrelevant of activation status) demonstrated similar levels of immunoreactivity in HCC tumors growing in the cecum, subcutis, or liver of nude mice, indicating that total EGF-R levels are not altered after growth in these different microenvironments. Controls included immunohistochemistry for total and activated EGF-R levels in HCC cells growing in vitro under serum-free or EGF-stimulated conditions and A431-epidermoid carcinoma growing in nude mice. Western blot analyses confirmed the specificity of the antibodies for the activated EGF-R. These results suggest that the production of liver metastasis by HCC cells depends in part on the response of tumor cells to organ-derived growth factors and hence the activation of specific cell surface tyrosine kinase receptors.
Animals↗
Epidermal growth factor receptor and insulin-like growth factor-I receptor expression and function in human soft-tissue sarcoma cells.
Epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) receptors are implicated in the development and progression of several malignancies including osteogenic and soft tissue sarcomas (STS). To determine a role for ligand-mediated receptor activation in sarcoma progression, the relative expression and function of EGF-R, IGF-I-R, and several other molecular determinants implicated in the progression of mesenchymal neoplasms were evaluated in human sarcoma cells established from surgical specimens of primary and metastatic tumors. mRNA blot analyses demonstrated the expression of c-Met, p53, and MDM2-specific transcripts. Western blot analyses confirmed the production of high levels of p53 protein; however, minimal levels of MDM2 and c-Met proteins were detected. Analysis of STS cells #23, #26, and #50 originating from an unclassified sarcoma lung metastasis, a malignant fibrous histiocytoma lung metastasis, and a dedifferentiated chondrosarcoma, respectively demonstrated high steady-state levels of EGF-R and IGF-I-R mRNA transcripts and protein correlating with receptor-specific tyrosine kinase activity and autophosphorylation in response to ligand. Treatment of these STS cells with EGF resulted in a >5 fold increase in DNA synthesis and mitogenesis compared with untreated controls. In contrast, treatment with IGF-I showed a variable STS growth response correlating with the origin of the tumor. These data support the involvement of EGF-R and IGF-I-R in the growth and metastasis of human soft tissue sarcoma and may offer new targets for therapeutic intervention in the management of this disease.
Blotting, Western↗
Expression of epidermal growth factor receptor and human papillomavirus E6/E7 proteins in cervical carcinoma cells.
BACKGROUND: Epidermal growth factor receptor (EGF-R) proteins are highly expressed in many tumors, including those of the cervix. We have observed previously that the introduction of a transcription unit containing an antisense sequence for the E6/E7 genes of human papillomavirus (HPV) 18, along with a transcription unit containing a sense complementary DNA sequence for the wild-type retinoblastoma (Rb) gene, decreased the growth of human cervical carcinoma HeLa cells (HPV 18 positive) both in vitro and in vivo. To clarify the regulatory mechanisms by which this reduction in cell proliferation occurred, we studied the expression of EGF-R proteins in these cells. METHODS: Western blot and northern blot techniques were used to measure EGF-R expression, and a pulse-chase immunoprecipitation assay was used to measure the stability of EGF-R protein in HeLa cells and HeLa cells that had been transfected with the antisense E6/E7 or sense Rb sequences. Cell proliferation was measured by use of a tetrazolium-based colorimetric assay for numbers of viable cells. RESULTS: The introduction of sense Rb or antisense E6/E7 transcription units or a combination of these two transcription units into HeLa cells dramatically decreased the level of EGF-R proteins in these cells; EGF-R levels were not affected at the transcriptional level but at the post-transcriptional level. Addition of the anti-EGF-R-specific monoclonal antibody 225mAb to HeLa cells caused 53% (95% confidence interval = 44%-62%) growth inhibition. CONCLUSIONS: These results suggest that HeLa cervical carcinoma cells are dependent on EGF-R for proliferation and that changes in functional levels of the E6/E7 HPV proteins and endogenous Rb proteins may alter the growth rate of cervical cancer cell lines by reducing the stability of EGF-R at the post-transcriptional level.
Blotting, Northern↗
Influence of the host microenvironment on the clonal selection of human colon carcinoma cells during primary tumor growth and metastasis.
The purpose of this study was to determine the subpopulation dynamics of human colon carcinoma (HCC) cells growing at orthotopic (cecum, liver) or ectopic (subcutis, kidney, spleen) sites in nude mice and to correlate any outgrowth of distinct clones with the differential expression of metastasis-related genes. Low metastatic KM12C HCC cells were genetically tagged with a retrovirus harboring the neomycin-resistance (Neo(R)) gene. Southern blot analyses demonstrated only minor resolution of the Neo(R) hybridization pattern in DNA isolated from primary tumors growing orthotopically or ectopically, suggesting a polyclonal outgrowth. In contrast, a major resolution of the Neo(R) hybridization pattern was observed in liver-specific metastases, demonstrating the outgrowth of single dominant clones. Expression of epidermal growth factor receptor (EGR-R) increased 20-60% in the liver metastases vs spleen tumors and the KM12C Neo(R) cells. Transforming growth factor alpha (TGF-alpha), amphiregulin (AR), and c-met showed only modest differences in mRNA expression. A 20-80% increase in type IV collagenase mRNA levels was also observed in all tumor specimens. Furthermore, expression of the multi-drug resistance gene PGY-1 and the carcinoembryonic antigen (CEA) gene were elevated in the liver metastases compared with the spleen tumors and cultured cells. Transcript levels of the angiogenic factors interleukin-8 and basic fibroblast growth factor did not correlate with clonal outgrowth. These data demonstrate a correlation between EGF-R, type IV collagenase, CEA, and PGY-1 gene expression and the production of liver metastases. Our results suggest that distinct HCC clones differentially expressing specific mRNA transcripts for metastasis-related genes are the forerunners of the experimental liver metastatic lesions.
Animals↗
Expression of five selected human mismatch repair genes simultaneously detected in normal and cancer cell lines by a nonradioactive multiplex reverse transcription-polymerase chain reaction.
Abnormalities in at least 1 of 5 mismatch repair (MMR) genes (hMSH2, hMLH1, hPMS1, hPMS2 and GTBP/hMSH6) are found in hereditary nonpolyposis colon cancer and sporadic colon cancers. We used a single-reaction multiplex reverse transcription (RT)-polymerase chain reaction (PCR), with the beta-actin gene as an internal control, to simultaneously evaluate expression of these 5 known human MMR genes in normal and tumor cell lines with known or uncharacterized mutations in MMR genes. The relative quantitation of the transcripts is demonstrated by controlling the number of PCR cycles and titrating cDNA with a dose-curve. The 13 normal cell lines tested were derived from normal lymphocytes, skin, thymus, breast, lung, colon, liver and kidney. The 26 cancer cell lines were derived from melanoma and cancers of the brain, breast, lung, colon, pancreas and prostate. All 5 MMR genes were ubiquitously expressed in all normal cell lines tested, suggesting their housekeeping roles. Aberrant MMR gene expression was only observed in the colon cancer cell lines. Two previously uncharacterized colon cancer cell lines did not express hMLH1. These data suggest that this nonradioactive multiplex RT-PCR assay for MMR gene expression may be useful for fast screening for genetic alterations that may affect gene expression and so may aid molecular analysis of MMR-related colon cancer.
Adaptor Proteins, Signal Transducing↗
Therapy of human transitional cell carcinoma of the bladder by oral administration of the epidermal growth factor receptor protein tyrosine kinase inhibitor 4,5-dianilinophthalimide.
Epidermal growth factor receptor (EGF-R), a transmembrane glycoprotein that mediates the mitogenic response of cells to epidermal growth factor, is highly expressed on malignant human bladder cancer cells. The 4,5-dianilinophthalimides represent a novel class of inhibitors of the EGF-R family of tyrosine kinase with selectivity at the enzymatic and cellular levels. Two compounds of this class, CGP 54211 and CGP 53353, inhibited tyrosine kinase activity of the EGF-R in five different human transitional cell carcinoma lines. The compounds also produced cytostasis in vitro. Highly metastatic human 253J B-V cells were implanted in the bladder wall of nude mice. The daily oral administration of CGP 54211 inhibited the level of EGF-R phosphorylation in this tumor; necrosis and inhibition of tumor growth paralleled this inhibition.
Adenosine Triphosphate↗
Search for genes that suppress cancer metastasis.
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Chromosomes, Human, Pair 6↗
Regulation of vascular endothelial growth factor expression in human colon carcinoma cells by cell density.
To determine the effect of cell density on vascular endothelial growth factor (VEGF) expression and the mechanism of this effect, four human colon cancer cell lines were grown as sparse or confluent monolayers or as spheroids. VEGF mRNA increased > 2-fold in cells grown as confluent monolayers or spheroids compared with cells grown as sparse monolayers. Semiquantitative reverse transcription-PCR demonstrated a 2-fold increase in the larger VEGF mRNA isoform (189 bp) in confluent cells. Sparse cells grown in conditioned medium from confluent cells demonstrated a > 2-fold increase in VEGF mRNA. These data suggest that VEGF expression may be regulated by an unidentified soluble factor.
Base Sequence↗
Regulation of carcinoembryonic antigen expression in human colon carcinoma cells by the organ microenvironment.
The expression of carcinoembryonic antigen (CEA) is thought to be involved in homotypic adhesion and has been associated with the progression of human colon carcinomas (HCC) to the metastatic state. Three cell lines established from surgical specimens of Dukes' stage D (KM20) or Dukes' stage B (KM12C, KM12SM) with high and low preoperative CEA serum levels, respectively, were studied subsequent to growth in culture, in the subcutis (ectopic) or cecal wall (orthotopic) of nude mice. In all cell lines, CEA expression was higher in cecal tumors than in subcutaneous lesions. The degree of differentiation and CEA expression by HCC growing in the cecal wall of nude mice correlated with the pathological diagnosis and preoperative CEA level of the original patients. To better understand the regulation of CEA expression, the HCC cells were grown in culture as sparse and confluent monolayers or as multicell spheroids. The CEA expression level increased in all three cell lines growing as confluent monolayers and was highest in multicell spheroids. Treatment of sparse monolayer cultures of KM12SM cells with mitomycin-C inhibited cell division and was associated with higher production of CEA protein. Moreover, conditioned media from confluent monolayer cultures or from spheroids up-regulated CEA production in sparse monolayer cells. These data show that CEA expression in HCC cells may be regulated by cell density and by factors from the organ environment.
Animals↗
Molecular determinants in the biology of liver metastasis.
A primary goal of cancer research is an increased understanding of the molecular mechanisms mediating the process of cancer metastasis. Analyses of colon cancer cells (the seeds) and the microenvironment (the soil) has increased our understanding of the biologic mechanisms mediating liver-specific metastasis. Insight into the molecular mechanisms regulating the pathobiology of cancer metastasis as well as a better understanding of the interaction between the metastatic cell and the host environment should produce a foundation for new therapeutic approaches. In this article we summarize experimental observations demonstrating the importance of specific factors that regulate various steps in the metastatic cascade. Furthermore, this article emphasizes the importance of the host organ's microenvironment and its role in liver metastasis formation. The production of metastases depends, in part, on the interaction of particular tumor cells with specific organ environments. Therefore, the successful metastatic cell must be viewed currently as a cell receptive to its environment. The analyses presented herein add important evidence to support the concept that cancer metastasis is not a random process; it is a highly regulated process that can be analyzed on the molecular level. To the clinician, it is readily apparent that by the time metastasis forms, most steps in the metastatic cascade have been completed. Therefore, therapy targeted to downregulate or interrupt the last stages of metastasis, proliferation and angiogenesis, should be the areas of greatest investigation in regards to treating established metastasis, whether they are microscopic or macroscopic.
Animals↗
Soluble Fas/APO-1 in tumor cells: a potential regulator of apoptosis?
Fas/APO-1, a member of the NGF/TNF receptor superfamily expressed on the cell-surface of normal and malignant cells, is known to induce cell death by apoptosis. In the present study, we have investigated Fas/APO-1 gene defects in a human osteosarcoma cell line resistant to the apoptosis-inducing effects of anti-Fas. cDNA cloning and sequencing revealed that these cells contained both 'authentic' and mutant Fas/APO-1 containing a 63 base pair in-frame deletion spanning the transmembrane domain, designated DFas/APO-1. Direct evidence for the existence of a soluble Fas/APO-1 protein was obtained by immunoprecipitation and Western blotting. Taken together with prior studies demonstrating a role for Fas/APO-1 and Fas ligand, respectively, in tumor target cell killing by cytotoxic T-lymphocytes, production of soluble Fas/APO-1 might have significant implications in malignant disease pathogenesis.
Antigens, Surface↗
Transcriptional induction of the melanocyte-stimulating hormone receptor in brain metastases of murine K-1735 melanoma.
Metastatic K-1735 murine melanoma cells are amelanotic in culture or in the subcutis of syngeneic mice. When injected into the internal carotid artery, these cells produce melanotic brain metastases. The production of melanin in tumor cells growing in the brain was directly correlated with induction of melanocyte-stimulating hormone receptor (MSH-R) steady-state mRNA transcripts. K-1735 cells isolated from brain lesions and implanted into the subcutis or grown in culture lose MSH-R transcripts and become amelanotic. In contrast to K-1735 cells, B16-BL6 melanoma cells constitutively produce melanin and express high levels of MSH-R mRNA regardless of the site of growth. Somatic cell hybrids between K-1735 and B16 cells produced melanin and expressed high levels of MSH-R mRNA transcripts, regardless of the site of growth, suggesting the dominance of the B16 phenotype. Treatment with alpha-MSH failed to upregulate MSH-R expression in cultured K-1735 cells or to maintain MSH-R expression in K-1735 cells isolated from brain metastases to be grown in culture. Responsiveness to alpha-MSH as determined by cell proliferation, melanin production, and intracellular accumulation of cyclic AMP directly correlated with MSH-R expression. These data demonstrate that a specific organ environment influences the phenotype of metastatic cells by regulation of specific genes that encode for cell surface receptors.
Animals↗
Modulation of tumor cell gene expression and phenotype by the organ-specific metastatic environment.
The mechanistic basis of a metastatic cell's ability to proliferate in the parenchyma of certain organs and develop organ-specific metastases is under intense investigation. Signals from paracrine or autocrine pathways, alone or in combination, may regulate tumor cell proliferation with the eventual outcome dependent on the net balance of stimulatory and inhibitory factors. This article summarizes recent reports from our laboratory and others demonstrating that the organ microenvironment can profoundly influence the pattern of gene expression and the biological phenotype of metastatic tumor cells, including induction of melanocyte stimulating hormone receptor and production of melanin, regulation of terminal differentiation and apoptosis, resistance to chemotherapy, and regulation of growth at the organ-specific metastatic site. These recent data from both murine and human tumor models support the concept that the microenvironment of different organs can influence the pattern of gene expression and hence the phenotype of tumor cells at different steps of the metastatic process. These findings have obvious implications for the therapy of neoplasms in general and metastases in particular.
Animals↗
Heterogeneity of cytokine and growth factor gene expression in human melanoma cells with different metastatic potentials.
The purpose of this study was to determine the mRNA expression level of multiple cytokine and growth factor genes in human malignant melanoma. Melanoma cells were isolated from several surgical specimens, adapted to growth in culture, characterized for their ability to produce experimental metastases in nude mice, and assessed for cytokine and growth factor steady-state gene expression. Highly metastatic in vivo- and in vitro-derived variants isolated from a single melanoma, A375, were also analyzed. Northern blot analyses revealed that all melanomas analyzed constitutively expressed steady-state mRNA transcripts for the growth and angiogenic factors, basic fibroblast growth factor (bFGF), and transforming growth factor alpha (TGF-alpha), which correlated with metastatic propensity. Only one highly metastatic melanoma, TXM-1, originally isolated from a lymph node metastasis, expressed mRNA transcripts specific for monocyte chemotactic and activating factor (MCAF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Similarly, of the nine melanomas examined, only TXM-1 expressed interleukin (IL)-1 alpha, IL-1 beta, and IL-6, important immunomodulatory cytokines. These data demonstrate the differential and heterogeneous expression of cytokine and growth factor genes in human malignant melanoma.
Animals↗
Level and function of epidermal growth factor receptor predict the metastatic potential of human colon carcinoma cells.
The purpose of this study was to determine whether production of liver metastasis by human colon carcinoma (HCC) cells depends on the response of tumor cells to organ-derived growth factors. HCC cells were isolated from several surgical specimens whose malignant potential differed (Dukes' stage B or D tumors), adapted to grow in culture, and assessed for expression of the epidermal growth factor receptor (EGF-R). Northern blot analyses revealed that highly metastatic HCC cells expressed >5-fold the number of EGF-R mRNA transcripts as low metastatic cells. The level of mRNA correlated with the amount of EGF-R protein as detected by Western blotting, immunohistochemistry, and Scatchard analyses. HCC growth response in vitro to picograms of transforming growth factor alpha was associated with functional cell surface EGF-Rs as determined by receptor tyrosine kinase activity assays. The EGF-R gene was not amplified or rearranged in highly metastatic cells. However, fluorescence in situ hybridization analysis showed that the copy number of chromosome 7 was higher in the highly metastatic cells. HCC cells were selected in vitro for low or high expression of EGF-R. Subsequent to injection into nude mice, only cells with high expression of EGF-R produced a high incidence of liver metastasis. These data demonstrate that expression of EGF-R by HCC cells directly correlates with their ability to produce hepatic metastasis.
Animals↗
Human recombinant interferons-beta and -gamma decrease gelatinase production and invasion by human KG-2 renal-carcinoma cells.
We investigated the effects of human recombinant interferons (r-IFNs) on gelatinase production and invasion by human renal-cell carcinoma (HRCC). Incubation of KG-2 HRCC with human r-IFN-beta or -gamma (but not -alpha) suppressed transcription of the 72-kDa gelatinase gene and, hence, production of gelatinase activity. These inhibitory effects of interferons (IFNs) were independent of their antiproliferative effects. Treatment of KG-2 cell with r-IFN-beta or -gamma significantly inhibited cell invasion through reconstituted basement membrane toward chemoattractants produced by kidney fibroblasts. The inhibitory activity of r-IFNs was specific to the KG-2 cells since gelatinase activity by various fibroblasts was unaffected. These findings suggest that r-IFN-beta or IFN-gamma may be used to inhibit the invasive potential of HRCC.
Carcinoma, Renal Cell↗
Organ-specific modulation of steady-state mdr gene expression and drug resistance in murine colon cancer cells.
BACKGROUND: The major cause of death from cancer is metastases that are resistant to conventional therapies. The resistance of metastatic tumor cells to chemotherapy can be caused by their intrinsic properties, such as increased expression of the mdr genes. PURPOSE: The purpose of our present study was to determine some of the mechanisms by which the organ microenvironment influences the response of tumor cells to chemotherapy. METHODS: Murine CT-26 colon cancer cells growing in continuous culture (parental cells) were harvested and injected subcutaneously into the lateral flank (to produce subcutaneous tumors) or the lateral tail vein (to produce experimental lung metastases) of 10 8-week-old syngeneic male BALB/c mice. Seven days after tumor-cell injection, the mice were given intravenous injections of either doxorubicin (10 mg/kg) or 0.9% NaCl (controls). This in vivo injection was repeated 7 days later. Mice with subcutaneous tumors and lung metastases were killed by cervical dislocation on day 21, and tumor samples from control mice were harvested and adapted to culture. The sensitivity of the cultured cells to doxorubicin and fluorouracil (5-FU) was determined at multiple time points. Levels of mdr-1 DNA were measured by slot-blot and Southern-blot analyses. mdr mRNA expression levels were measured by Northern-blot analysis using mdr-1- and mdr-3-specific hybridization probes, and P-glycoprotein level was determined by fluorescence-activated cell sorting using different monoclonal antibodies. RESULTS: Treatment with doxorubicin produced 80% growth inhibition of CT-26 subcutaneous tumors but had little effect on the number (and size) of experimental lung metastases. Collectively, the results suggest that the multidrug-resistant phenotype developed in CT-26 cells growing in the lung environment. Cultures established from lung metastases were initially resistant to doxorubicin (but not to 5-FU) and showed elevated expression of mdr-1 mRNA transcripts and P-glycoprotein. This resistance could be overcome by verapamil and disappeared after 21 days in culture. No mdr gene amplification was detected. The expression level of mdr-specific mRNA (predominance of mdr-1) and P-glycoprotein was directly associated with resistance to doxorubicin. CONCLUSIONS: Results of this study have demonstrated that the in vivo sensitivity of murine CT-26 colon carcinoma cells to doxorubicin depends on the organ environment. The organ environment can influence the P-glycoprotein-mediated multidrug-resistant phenotype in tumor cells, and the increased expression of P-glycoprotein is transient; once removed from the environment (lung), the cell's resistance reverts to that of the sensitive parent cells.
ATP Binding Cassette Transporter, Subfamily B, Mem↗