Effect of NCAM-transfection on growth and invasion of a human cancer cell line

A cDNA encoding the human transmembrane 140 kDa isoform of the neural cell adhesion molecule (NCAM) was transfected into the highly invasive MDA-MB-231 human breast cancer cell line. Transfectants with a homogeneous expression of NCAM showed a restricted capacity for penetration of an artificial basement membrane. However, when injected into nude mice, both control and NCAM-expressing cell lines produced equally invasive tumors. Tumors generated from NCAM-transfected cells were heterogeneous, containing NCAM-positive as well as NCAM-negative areas, indicating the existence of host factors capable of modulating NCAM expression in vivo. In nude mice, NCAM-transfected cells developed tumors with longer latency periods and slower growth rates than tumors induced by NCAM-negative control cells, implying that NCAM may be involved not only in adhesive and motile behavior of tumor cells but also in their growth regulation. There was no indication of differences in cell proliferative characteristics between the different NCAM-transfected and the control transfected cells as determined by flow cytometric DNA analysis, suggesting an increased cell loss as the reason for decreased in vivo growth rate of the NCAM-transfected cells. The fact that NCAM expression influences growth regulation attributes a pivotal role to this cell adhesion molecule during ontogenesis and tumor development.     

Adenovirus-mediated expression of PML suppresses growth and tumorigenicity of prostate cancer cells

Our previous studies demonstrated that the promyelocytic leukemia gene, PML, encodes a growth and transformation suppressor. Overexpression of PML inhibits cancer cell growth in vitro and in vivo. In this study, we further explored the possibility of applying PML as a potential agent for developing prostate cancer gene therapy using an adenovirus delivery system. We have constructed and produced the recombinant PML-adenovirus, Ad-PML, in which the full-length PML cDNA is driven by the strong cytomegalovirus promoter. In LNCaP, DU145, and PC-3 prostate cancer cell lines, an infection efficiency of 90% can be achieved at a concentration of 2, 10, and 100 multiplicity of infection (MOI), respectively. Western blotting and immunofluorescence staining demonstrated that the AD-PML-infected cells expressed a high level of PML protein. The protein expression peaked at days 3-4 postinfection, and a detectable level of PML was found at day 18 after viral infection. To test the effect of Ad-PML on the growth of prostate cancer cells, the DU145 and LNCaP cells were infected with 10 and 2 MOI of Ad-PML. We found that the growth rate of the Ad-PML-infected DU145 and LNCaP cells were significantly inhibited. A tumorigenicity test in nude mice showed that the Ad-PML-treated DU145 cells failed to form tumors. Most importantly, direct injection of Ad-PML into DU145-induced tumors was able to repress tumor growth in nude mice by 64%. Taken together, these data indicate that PML is a tumor growth suppressor in prostate cancer and that Ad-PML may be a potential candidate for human prostate cancer therapy.     

Tumor suppressor activity of the TGF-beta pathway in human cancers

Immunodeficient animals, principally nude mice, when used in appropriately designed studies have been shown to be useful for the experimental analysis of human breast cancer metastasis. As with many other human tumors, the implantation of breast cancer cells into an anatomically appropriate tissue (the mammary fatpad) results in increased tumor take and incidence of metastasis for certain cell lines compared with subcutaneous injection. Testing a number of widely available human breast cancer cell lines identified the MDA-MB-435 cell line as the most metastatic, producing lung and lymph node metastases in a high proportion of nude and severe combined immunodeficient (SCID) mice after injection in the mammary fatpad. Mixing human breast cancer cells with normal fibroblasts or with Matrigel also increases the tumor incidence and growth rates in nude mice. Different routes of injection can be used to assess the ability of human breast cancer cells to form metastatic lesions in the lungs (i.v. injection), the liver (injection in the spleen), the brain (direct or intracarotid artery injection) and the bone marrow and bone (injection into the left ventricle of the heart). These different approaches demonstrate the potential of experimental studies of human breast cancer growth and metastasis using immunodeficient mice; this model is valuable for experiments that test the role of metastasis-associated genes and the efficacy of novel forms of therapy.     

Inhibition of caspases by cytokine response modifier A blocks androgen ablation-mediated prostate cancer cell death in vivo

Androgen withdrawal is a major therapeutic modality in the treatment of prostate cancer. Although tumors initially respond, they subsequently relapse, and these recurring tumors are androgen independent. To examine possible mechanisms to explain the androgen independence of prostate cancer, we have expressed cytokine response modifier A (CrmA), a competitive inhibitor of caspases, interleukin 1beta-converting enzyme-like proteases, which mediate apoptotic cell death, in the human androgen-dependent prostate cancer cell line LNCaP. LNCaP cells require androgens for continuous growth in culture and to form tumors in nude mice. The expression of CrmA in LNCaP cells prevented the decreased growth rate induced by androgen withdrawal in tissue culture. When CrmA-expressing LNCaP (LNCaP-CrmA) cells were implanted s.c. in nude mice, the tumors grew six times faster than parental cells. Androgen ablation by castration before tumor implantation suppressed the ability of control LNCaP cells expressing nonfunctional CrmA mutant (R291T) to form tumors, but LNCaP-CrmA cells formed tumors similar in size to those formed in normal mice. When orchiectomy was performed 10 days after tumor implantation, control LNCaP cells expressing a nonfunctional CrmA mutant (R291T) regressed, but LNCaP-CrmA tumors continued to grow. Thus, inhibition of caspases prevents androgen withdrawal-induced prostate cancer cell death, suggesting that caspase activation is normally an important part of this process.     

Anticancer efficacy in vivo and in vitro, synergy with 5-fluorouracil, and safety of recombinant methioninase

The elevated exogenous-methionine dependency of tumors for growth has been observed in all major cancer cell types. We have previously cloned a methioninase (rMETase) from Pseudomonas putida to deplete methionine. Growth inhibition followed by apoptotic cell death was induced by treatment of tumor cells with rMETase in vitro. A single i.p. injection of 300 units of rMETase can lower the serum methionine level in the mice from 70 microM to less than 1 microM within 2 h and maintain this depleted level for 8 h. Repeated dosing of rMETase of tumor-bearing mice could be administered without acute immune-hypersensitivity. rMETase treatment demonstrated growth inhibitory activity against human tumors in nude mice, including those which were multiple drug-resistant. No body weight loss or hematotoxicity, except a slight anemia, was found throughout the therapy. The combined treatment of the Lewis lung carcinoma with a fixed rMETase dose and increasing doses of 5-fluorouracil (5-FU) resulted in a dose-dependent enhanced antitumor efficacy for survival as well as tumor growth inhibition. Thus, methionine depletion by rMETase potentiates the antitumor efficacy of 5-FU. The data presented in this report thus indicate that rMETase is active alone, is synergistic in combination with 5-FU, and has negligible toxicity suggesting a novel clinical approach for effective cancer therapy.     

Magnetic resonance imaging and invasive evaluation of development of heart failure in transgenic mice with myocardial expression of tumor necrosis factor-alpha

The intestine is a large endocrine organ, but the dependence of colon cancer on hormones remains unknown. We show here that neurotensin, a paracrine/endocrine peptide in the gut, and the neurotensin receptor antagonist SR 48692 control colon cancer cell growth in vitro and in vivo by interacting with receptors that are ectopically expressed in colon cancers. In cell culture, neurotensin stimulates the growth of human colon cancer cell lines (SW480, SW620, HT29, HCT116 and Cl.19A) expressing the neurotensin receptor NTR1 but does not change the growth of Caco2 cells, which do not express NTR1. In SW480 cells, neurotensin is active in the 10(-10) to 10(-6) M concentration range (ED50 = 0.47 nM) while the neurotensin fragment (I-II) is inactive. Neurotensin also enhances the cellular cloning efficiency of SW480 cells in soft agar by inducing a 50% increase of colony formation. This effect is blocked by SR 48692, which alone does not alter colony formation. Subcutaneous delivery of neurotensin (0.54 micromol/kg every 24 hr) by osmotic pumps to nude mice that have been xenografted with SW480 cells results in a significant increase of tumor volume, i.e., up to 255% of control at day 20 of treatment. SR 48692 administered alone (1.7 micromol/kg every 24 hr) by daily i.p. injections reduces the development of tumors formed by xenografting SW480 cells in nude mice. A significant mean reduction of tumor volume of 38% is observed during the 22-day period of treatment. SR 48692 alone is also active at reducing tumor volume after xenografting HCT116 cells in nude mice. Our results support the notion that colon cancer growth may be dependent on blood-borne neurotensin and suggest that non-peptide neurotensin antagonists, such as SR 48692, may be useful for the development of novel therapeutic strategies of colon cancer.     

Isolation and characterization of a spontaneously transformed malignant mouse mammary epithelial cell line in culture

A method is described that permits the selection of spontaneously transformed mammary epithelial colonies from an untransformed mouse mammary epithelial cell line, NMuMG, and utilizes a long-term anchorage-independent growth of the transformants on soft agarose. These transformed cells (NMuMG-ST) are shown to be distinguishable from the untransformed cells by morphology, growth characteristics, induced carcinomas when transplanted into nude mice and ability to metastasize. This transformed phenotype displayed focal, multilayer growth and higher saturation density in comparison with the untransformed phenotype. Transplanted tumors as well as metastatic lung tumors in nude mice were adenocarcinomas morphologically similar to typical mammary tumors in humans. This selection procedure of mutant mammary cells from an immortalized cell line derived from normal mammary glands could be very useful to identify the genomic biomarkers in the growth regulation and malignant progression of breast cancer.     

Rehabilitation approach to children with sequelae of hypoxic encephalopathy

OBJECTIVES: The dependence of human prostate carcinoma growth on hormone was studied in xenotransplants in nude mice. The objective was to determine differences in cell kinetic parameters and volume growth of tumors growing with alpha-dehydrotestosterone (alphaDHT) and without alphaDHT. These differences could be used as arguments pro and contra the adaptation versus the clonal selection hypothesis. METHODS: Human prostate carcinomas were xenotransplanted into nude mice. Growth of tumors was observed in castrated male mice without and with implanted osmotic pumps secreting alphaDHT. In a further series of experiments the alphaDHT tubes were removed when the tumors had reached a volume of 0.3 cm3. Tumor volume was measured to determine tumor doubling time with and without alphaDHT. Detailed cell kinetics were analyzed using the bromodeoxyuridine (BrdUrd) method with flow cytometry. Applying the relative movement (RM) and a simulation analysis to parallel single and multiple BrdUrd labelling experimental data we determined transit times through the phases of cell cycle, potential doubling time Tpot, growth fraction (GF) and cell loss. RESULTS: Five human prostate carcinomas were xenotransplanted into nude mice. Tumor take was only achieved when androgen hormone was present. However, when alphaDHT was removed when the tumors had grown to a volume of 0.3 cm3, they continued to grow at nearly the same Td as those tumors with continued alphaDHT application. The BrdUrd experiments, on the other hand, showed considerable increase of Tc and Tpot upon withdrawal of alphaDHT in 4 out of 5 tumors. The GF and labelling index (LI) were maintained at about the same level as alphaDHT consuming tumors. CONCLUSION: While small transplanted tumor pieces do not grow without alphaDHT, larger tumors grow with the same Td after removal of alphaDHT. The slower proliferation shown by the increased Tc and Tpot is balanced by less cell loss. Since GF and LI were maintained at about the same level, we conclude that in our tumors the majority of cells adapted to hormone independence. There was no evidence for the selection model since the tumors continued to grow at about the same speed after hormone depletion. All cell kinetic parameters showed a considerable inter- and intratumoral heterogeneity. A clinical implication may be that hormone ablation therapy should always be supplemented by some other therapy.     

Alternative splicing of fibroblast growth factor receptor 2 (FGF-R2) in human prostate cancer

Progression of prostate cancer from an androgen sensitive to androgen insensitive tumor has previously been shown to be accompanied by a change in alternative splicing of fibroblast growth factor receptor 2 (FGF-R2) in a rat model of prostate cancer. This change results in loss of the FGF-R2(IIIb) isoform and predominant expression of the FGF-R2(IIIc) isoform. We sought to determine whether this change in FGF-R2 splicing is also associated with androgen insensitivity in human prostate tumors. We analysed three well characterized human prostate cancer cell lines and three metastatic prostate tumors which have been maintained as xenografts in nude mice. One of the cell lines, LNCaP, and two of the xenografts, DUKAP-1 and DUKAP-2, have been characterized as androgen sensitive, whereas two of the cell lines, DU-145 and PC-3, and one of the xenografts, DU9479, display androgen independent growth. Using an RT-PCR based assay, we demonstrated that progressive loss of the FGF-R2(111b) isoform correlated with androgen insensitivity in these human prostate cancer models. These findings lend support to the hypothesis that that loss of FGF-R2(IIIb) may be one step in a series of events which lead to progression of human prostate cancer.     

Lipoxygenase inhibitors prevent lung carcinogenesis and inhibit non-small cell lung cancer growth

The effects of lipoxygenase inhibitors were investigated using human lung cancer cell lines and A/J mice. By RT-PCR, 5-, 12-, and 15-lipoxygenase mRNA was detected in NSCLC cells. NDGA inhibited 5-LO activity in adenocarcinoma cell line NCI-H1264. Using an MTT assay, NDGA, MK591 and AA861 inhibited the growth of NSCLC cell lines tested with IC50 values of 3, 2, and 7 microM, respectively. Using a clonogenic assay, 10 microM NDGA significantly reduced NSCLC colony number. NDGA significantly slowed NSCLC xenograft growth in nude mice. When the tumors were excised and analyzed, nude mice treated with NDGA had significantly more apoptotic figures than did untreated tumors. A/J mice treated with urethane developed adenomas after 4 months and NDGA administration significantly reduced lung adenoma number. These data indicate that lipoxygenase inhibitors inhibit lung cancer growth and prevent lung carcinogenesis.     

Networking rural health resources. The woman who cried wolf

OBJECTIVE: To study the genetic stability and to establish a method for detection of micrometastasis using microsatellite DNA in human breast cancer xenograft in nude mice. METHODS: Fresh tissue of human breast cancer was xenotransplanted in nude mice or thotopically. Genomic DNA extracted from tissues of human breast cancer, xenotransplanted tumors and metastatic foci in nude mice were PCR amplified at three microsatellite loci (D14S68, D18S69, D20S199) and were analysed by electrophoresis and silver stain on PAGE. RESULTS Microsatellite DNA in genome of the xenotransplanted tumors and metastatic foci in nude mice were identical with that of the human breast cancer. CONCLUSION: This study has demonstrated in nude mice the xenotransplanted tumors and metastatic foci that originated from human breast cancer. The genetic stability in human breast cancer is evident in the processes of xenotransplantation, serial passages in nude mice, metastasis and in vitro culture. This method is sensitive and specific for the discrimination of metastatic tumor cells.     

Plasma and red cell lipids in sickle cell disease

Lipids, in particular phospholipids, are essential components of membrane systems, and the measurement of phospholipids and cholesterol in plasma and tissues is helpful in diagnosis. Phospholipids represent about 60 to 70% of total red cell (RBC) lipids, while about 25% is free cholesterol. Lipids in RBC are present in a dynamic state of equilibrium, and the RBC have the capacity for rapid exchange of lipids with plasma in several ways. The present study examined the cholesterol and phospholipid levels of plasma and erythrocytes in male patients with sickle cell anemia and in healthy male individuals of comparable age. This was performed with a view to detecting possible differences that might be related to some of the RBC abnormalities which accompany the disease. The results show that plasma lipids are significantly reduced in patients with sickle cell anemia and that RBC cholesterol was higher in sickle cell patients than in normal subjects.     

Metastatic phenotype correlates with high expression of membrane-associated complete beta-human chorionic gonadotropin in vivo

BACKGROUND: Investigations using living human cancer cells and the nude mouse model were conducted to evaluate the expression of human chorionic gonadotropin (hCG) in various cancers grown in vitro and in vivo. The aim was to determine whether membrane-associated hCG in any of its forms is a characteristic metastatic marker, and at what levels or ratios. METHODS: Human cancer cell lines known to produce tumors that metastasize spontaneously when grown in nude mice (n = 4) were compared with those that do not produce such tumors (n = 4) using analytical (quantitative) flow cytometry. Monoclonal antibodies directed to epitopes of intact hCG (hCG-holo) and its subunits, including beta-human chorionic gonadotropin with its carboxy-terminal peptide (hCG beta-CTP), allowed for the determination of hCG beta-CTP/hCG-holo ratios. RESULTS: No significant difference in hCG beta-CTP/hCG-holo ratios was found between the cultured human cancer cells that do not metastasize spontaneously (ratio = 2.39) and those that do (ratio = 2.13), and no difference was seen in their growth rate in nude mice. However, the cells isolated from tumors that do not metastasize spontaneously showed a decrease in their ratios to values less than 1. They reverted to their original values after reestablishment in culture and subsequent passages. In contrast, the ratios shown by cells isolated from tumors that metastasize spontaneously increased to 3 to 6 times their original values in culture, then reverted to their original values after reestablishment in culture and subsequent passages. CONCLUSIONS: To our knowledge, these data demonstrate the following for the first time: 1) There is a direct in vivo correlation between human cancer cells that metastasize spontaneously in nude mice and the expression of membrane-associated complete hCG beta (hCG beta-CTP); and the correlation identifies this molecule as a characteristic metastatic phenotype marker. 2) The marked ratio variations under different conditions indicate that the metastatic phenotype is an unstable event. 3) Growth and local invasion in vivo correlates with the expression of hCG-holo.     

H-cadherin expression inhibits in vitro invasiveness and tumor formation in vivo

H-cadherin is a newly characterized cadherin molecule whose expression is decreased in a variety of human carcinoma cells, suggesting that it may play a role in maintaining normal cellular phenotype. To investigate how re-expression of H-cadherin could influence the malignant phenotype of human breast carcinoma cells in vivo, we transfected both control and H-cadherin expression vectors into human breast cancer cells (MDAMB435), which do not express H-cadherin constitutively. We found that invasiveness of these cells could be prevented by transfection with H-cadherin. We also compared the ability of control- and H-cadherin-transfected cells to induce subcutaneous tumors after injection into mammary fat pads of nude mice. Our results show that H-cadherin transfection produced a marked inhibition of tumor growth and modified the morphology of tumor cells: tumors from mice injected with control cells were significantly larger and contained larger cells having a higher degree of pleomorphism than those of tumors generated from carcinoma cells expressing H-cadherin. Altogether, these results indicate that H-cadherin expression antagonizes tumor growth in nude mice, presumably by enhancing cell-cell association in a tissue environment. These findings strongly suggest that H-cadherin could provide a possible target for corrective gene therapy against breast cancer.     

Expression of antisense CD44 variant 6 inhibits colorectal tumor metastasis and tumor growth in a wound environment

Up-regulation of CD44 variant isoforms has been linked to the progression of epithelial tumors and the metastatic phenotype. Here we report a functional role for CD44 variant isoforms in colorectal cancer metastasis. An antisense mRNA approach was used to down-regulate CD44 variant isoforms containing CD44 variant 6 (v6) in the metastatic colorectal tumor cell line HT29. Cell lines stably expressing antisense CD44 exon 10 (v6) showed reduced expression of alternatively spliced CD44 variant isoforms but no significant change in expression of CD44 core protein, as judged by immunohistochemical analysis using CD44 domain-specific monoclonal antibodies. Expression of antisense exon 10 (v6) had no effect on HT29 tumor cell proliferation in vitro or the ability of the cells to bind immobilized hyaluronan, but it resulted in a reduced capacity to form liver metastases in nude mice following intrasplenic injection. Metastases were not detected in nude mice inoculated with antisense CD44 exon 10 (v6)-expressing cell lines after 4 months, against a background of a 30% metastasis rate in the control HT29 parental and vector alone transfected lines. Furthermore, whereas 82% of mice intrasplenically injected with control HT29 parental and vector alone cell lines developed tumors in incisional wound sites, none of the mice injected with antisense exon 10 expressing HT29 cells developed similar tumors. This is the first demonstration that antisense RNA can be used to selectively inhibit expression of specific domains of a molecule generated through alternative mRNA splicing while allowing expression of core domains to remain unaffected. Furthermore, these results provide direct evidence for a functional role of CD44 variant isoforms in the metastasis of human colorectal tumor cells and may suggest a critical role for CD44 variants in promoting cell growth specifically in the cytokine/growth factor-enriched environment of a wound site.     

Overexpression of bcl-2 protects prostate cancer cells from apoptosis in vitro and confers resistance to androgen depletion in vivo

Normal (nonneoplastic) human prostatic secretory epithelial cells do not express the bcl-2 protein. However, a recent immunohistochemical survey of neoplastic human prostate tissues showed that a fraction of primary untreated prostate adenocarcinoma cells expressed this apoptosis-suppressing oncoprotein at significant levels (Colombel et al., Am. J. Pathol., 143: 390-400, 1993). Additionally, a number of hormone-refractory prostatic adenocarcinomas obtained from hormonally-treated patients (subsequent to surgical or drug castration therapy) were examined and were found to be uniform in their elevated expression of bcl-2 oncoprotein. The results of this preliminary survey imply that bcl-2 expression distinguishes a subgroup of primary human prostate cancers and that the expression of this protein might be a factor enabling prostate cancer cells to survive in an androgen-deprived environment. The current study was undertaken to determine the degree to which overexpression of bcl-2 can protect human prostate cancer cells from apoptotic stimuli in vitro and in vivo. Human prostate cancer cells (LNCaP) were transfected with a neomycin-selectable eucaryotic expression vector containing cDNA encoding human bcl-2. Transfected clonal variants that express bcl-2 protein (LNCaP/bcl-2) were unaltered with regard to their basal growth rate in 10% serum-containing medium, or with regard to their expression of the differentiated human prostate cell gene products prostate-specific antigen or androgen receptor protein. The bcl-2-transfected clones were altered, however, with regard to their growth rate in charcoal-stripped serum lacking dihydrotestosterone. Additionally, in contrast to the parental or control-transfected cell lines, LNCaP/bcl-2 cells were highly resistant to a variety of apoptotic stimuli in vitro including serum starvation and 10 nM phorbol ester (phorbol 12-myristate 13-acetate) supplementation of the medium. Lastly, the overexpression of bcl-2 by these prostate cancer cells altered their tumorigenic potential in a nude mouse assay. s.c. injections of 10(6) LNCaP/bcl-2 cells into male nude mice resulted in earlier and larger tumor formation compared to an equivalent injection of parental or control-transfected LNCaP cells. When these variant cell lines were injected into castrated male nude mice, only the LNCaP/bcl-2-transformed cells gave rise to tumors. Moreover, LNCaP/bcl-2 tumors grown in intact male nude mice were refractory to the growth-inhibiting effects of castration demonstrated by parental LNCaP cells. Data obtained in this study demonstrate that the bcl-2 oncoprotein can protect prostate cancer cells from apoptotic stimuli in vitro and suggest that such protection correlates with the ability to form hormone-refractory prostate tumors in vivo.     

Dietary fat and breast cancer metastasis by human tumor xenografts

Human breast cancer cell lines growing as xenografts in athymic nude mice have been used to examine the effects of dietary fat and fatty acids on tumor progression. The estrogen independent MDA-MB-435 cell line has the advantage that it metastasizes consistently to the lungs and forms quantifiable secondary nodules when injected into the mammary fat pads. With these breast cancer cells, the stimulating effects of polyunsaturated omega-6 fatty acids on both primary tumor growth and metastasis were demonstrated; in contrast, the long-chain omega-3 fatty acids were inhibitory. The model can also be adapted to examine dietary fatty acids, and inhibitors of their metabolism, as experimental adjuvant therapy after surgical excision of the primary tumors. Unfortunately, estrogen dependent human breast cancer cells do not metastasize, or do so rarely, in nude mice; in consequence, it is not possible to use the model to study estrogen-fatty acid interactions on the metastatic process. In addition to metastasis from a primary location, intravenous injection of MDA-MB-435 cells into the nude mouse host, particularly when combined with studies using Matrigel-based in vitro invasion assays, permits further dissection of the steps in the metastatic cascade which are influenced by dietary fatty acids. The results obtained by these several approaches have demonstrated distinct roles for the cyclooxygenase and lipoxygenase-mediated products of omega-6 fatty acid metabolism, and suggest new approaches to experimental breast cancer therapy.     

Antitumor activity of the novel human breast cancer growth inhibitor, mammary-derived growth inhibitor-related gene, MRG

A novel human tumor growth inhibitor was identified by differential cDNA sequencing. The predicted amino acid sequence of this tumor-suppressing factor has a significant sequence homology to mouse mammary-derived growth inhibitor and thus was named mammary-derived growth inhibitor-related gene (MRG). MRG was found to be expressed in normal and benign human breast tissues but not in breast carcinomas. In situ hybridization analysis demonstrated a stage-specific MRG expression as follows. MRG was barely detectable in breast carcinomas, showed partial and weak expression in benign hyperplasia, but was expressed at a high level in normal breast epithelial cells. To determine if MRG can modulate in vivo growth of human breast cancers, we transfected a full-length MRG cDNA into MDA-MB-231 human breast cancer cells and studied the orthotopic growth of MRG transfectants versus control transfectants in the mammary fat pad of athymic nude mice. Overexpression of MRG in human breast cancer cells significantly suppressed cell proliferation in vitro and tumor growth in an orthotopic nude mouse model. These results suggest that MRG has tumor-suppressing activity, and the loss of MRG expression may be involved in the development and progression of breast cancer.     

Prognostic relevance of the intrinsic growth deceleration of the first passage xenografts of human renal cell carcinomas

BACKGROUND: Although successful xenotransplantation of human tumors in nude mice highly predicts prognosis, little is known regarding the biologic background of this correlation. In this study, the relationship between the macroscopic growth pattern of first-generation xenografts of human renal cell carcinomas in nude mice and prognosis was studied. METHODS: Macroscopic growth patterns of the first-generation xenografts of locally confined renal cell carcinomas were analyzed according to the best-fit Gompertz recursion formulas. RESULTS: The parameter "b" of the growth pattern, the measure of the intensity of growth deceleration as a function of tumor growth, strongly predicted prognosis after nephrectomy as a single factor; faster growth deceleration, i.e., lower b values, predicted better prognosis (mean follow-up, 5.2 years; P = 0.000008 for the disease free period and P = 0.000018 for overall survival). It is also the most significant single prognostic parameter among others (including staging and grading) according to a multivariate analysis. CONCLUSIONS: The parameter expressing the Gompertzian macroscopic growth deceleration of the first-generation xenografts of clinically locally confined renal cell carcinomas in nude mice explains the strong prognostic impact of xenotransplantation.     

Inhibitory effects of oral administration of ginsenoside Rh2 on tumor growth in nude mice bearing serous cyst adenocarcinoma of the human ovary

We examined the inhibitory effect of the oral administration of ginsenoside Rh2 (Rh2) on tumor growth in nude mice bearing human ovarian cancer cells (HRA). In the first experiment, it was revealed that daily administration of 30 microM Rh2 significantly inhibited tumor growth. In the second experiment, therefore, various concentration of Rh2 (1, 15, 30, 60, 120 microM) were administered every day for 91 days, beginning the day after tumor inoculation. Treatment with Rh2 resulted in a remarkable retardation of the HRA cell tumor growth. In particular, tumor growth in mice treated with 15, 30 and 120 microM Rh2 was significantly inhibited, compared to that in CDDP treated mice as well as in untreated mice. Consequently, 50% survival in nude mice treated with 15, 30 and 120 microM Rh2 was significantly prolonged, compared to that not only in untreated mice but also in CDDP treated mice. No side effect was observed in any mice treated with Rh2. Red ginseng containing Rh2 has been used exclusively, orally administered. In the present study, we considered that oral administration of Rh2, which is a component of red ginseng, has strong inhibitory effects on human ovarian cancer cell growth in nude mice.