Search results for "Neoplastic"
showing 10 items of 2901 documents
Mast Cells Infiltrating Inflamed or Transformed Gut Alternatively Sustain Mucosal Healing or Tumor Growth.
2015
Abstract Mast cells (MC) are immune cells located next to the intestinal epithelium with regulatory function in maintaining the homeostasis of the mucosal barrier. We have investigated MC activities in colon inflammation and cancer in mice either wild-type (WT) or MC-deficient (KitW-sh) reconstituted or not with bone marrow-derived MCs. Colitis was chemically induced with dextran sodium sulfate (DSS). Tumors were induced by administering azoxymethane (AOM) intraperitoneally before DSS. Following DSS withdrawal, KitW-sh mice showed reduced weight gain and impaired tissue repair compared with their WT littermates or KitW-sh mice reconstituted with bone marrow-derived MCs. MCs were localized i…
Ha-rasVa112 but not p53Ser247 leads to a significant neoplastic transformation rate of the putative rat liver stem cells (oval cell)
1996
In order to test the controversially discussed hypothesis that oval cells are part of a liver stem cell compartment and can give rise to cholangiocellular as well as hepatocellular carcinomas in the course of liver carcinogenesis, we transfected an oval cell line established in our laboratory with an oncogenically activated genomic Ha-ras clone (pUC EJ 6.6), carrying a valine at position 12 instead of the wild-type glycine, or a rat p53 cDNA mutated by site-directed mutagenesis at codon 247, which corresponds to codon 249 in the human p53. This codon is of particular interest since it represents a mutation hotspot observed in hepatocellular carcinoma especially in regions with high aflatoxi…
Role of the Ha-ras gene in the malignant transformation of rat liver oval cells.
1997
We have shown that the oval cell line OCICDE 22 can be transformed by the highly carcinogenic fiord-region diol epoxides of benzo[c]phenanthrene. Mutational activation of the ras proto-oncogene family has been proposed to be a critical event in the formation of tumors induced by polycyclic aromatic hydrocarbons. Therefore, we investigated whether in the earlier transformed OCICDE 22 cells any point mutations were detected in the ras proto-oncogene. The results indicate that the malignant transformation of OCICDE 22 cells by the 4 stereoisomeric benzo[c]phenan-threne diol epoxides in vitro is independent of activation of the Ha-ras proto-oncogene. In addition, Northern and Western blot analy…
Interclonal heterogeneity in a human epithelioid-sarcoma cell line (Gru-1)
1994
Three clonal sub-populations, GRU-IA, GRU-IB, and GRU-IC, isolated from the human epithelioid sarcoma cell line GRU-I, were characterized morphologically, cytogenetically and with regard to proliferation kinetics. Immunocytochemically, major differences became evident in the expression of cytokeratin 18 and neurofilament proteins, which are indicative for epithelial and neural differentiation respectively. Vimentin, a mesenchymal differentiation marker, however, could be detected in all tumor cells of each sub-population. Laminin, a major compound of basement membranes, formed abundant intercellular network-like patterns in GRU-IB and GRU-IC, whereas GRU-IA was characterized by a diffuse in…
Low frequency of HLA haplotype loss associated with loss of heterozygocity in chromosome region 6p21 in clear renal cell carcinomas.
2004
HLA class I loss or downregulation is a widespread mechanism used by tumor cells to avoid tumor recognition by cytotoxic T lymphocytes favoring tumor immune escape. Multiple molecular mechanisms are responsible for these altered HLA class I tumor phenotypes. It has been described in different epithelial tumors that loss of heterozygosity (LOH) at chromosome region 6p21.3 is a frequent mechanism that leads to HLA haplotype loss, ranging between 40 and 50%, depending on the tumor entity analyzed. Here we have tested the frequency of LOH at 6p21 chromosome region in Renal Cell Carcinomas (RCC) of the clear cell and chromophobe subtype. A low frequency of HLA haplotype loss (6.6%) was found in …
O6-methylguanine-DNA methyltransferase activity and sensitivity to cyclophosphamide and cisplatin in human lung tumor xenografts
1998
The DNA repair protein O6-methylguanine-DNA methyl-transferase (MGMT) is a main determinant of resistance of cells to the cytostatic effects of O6-alkylguanine-generating alkylating agents. The purpose of our study was to assay MGMT activity in cells of lung cancers and to correlate MGMT levels with chemotherapy response to cyclophosphamide (CTX) and cisplatin (DDP). MGMT levels were determined in 14 human lung tumor xenografts. There was a wide variation of MGMT expression in these tumors, ranging from 10 to 984 fmol/mg protein. There was also a wide range in the sensitivity of the xenografts to CTX and DDP, as measured by specific growth delay. When the MGMT levels of the different xenogr…
Cathepsin D expression levels in nongynecological solid tumors: clinical and therapeutic implications.
2004
Cathepsin D is a lysosomal acid proteinase which is involved in the malignant progression of breast cancer and other gynecological tumors. Clinical investigations have shown that in breast cancer patients cathepsin D overexpression was significantly correlated with a shorter free-time disease and overall survival, whereas in patients with ovarian or endometrial cancer this phenomenon was associated with tumor aggressiveness and a degree of chemoresistance to various antitumor drugs such as anthracyclines, cis-platinum and vinca alkaloids. Therefore, a lot of research has been undertaken to evaluate the role and the prognostic value of cathepsin D also in other solid neoplasms. However, conf…
Carcinosarcoma of monoclonal origin arising in a dermoid cyst of ovary: a case report.
2005
Abstract Background Transformation of a cystic benign teratoma of the ovary into a "carcinosarcoma" has very rarely been reported and its histogenetic origin is still debated. Case presentation A case of carcinosarcoma arising from a dermoid cyst is reported. The tumor showed cystic areas delimited by normal squamous epithelium, with transitional areas through dysplastic epithelium to "in situ" and infiltrating squamous cell carcinoma (SCC). The sarcomatous component showed compact tissue composed of round cells concentrically arranged around small vessels, spindle, and pleomorphic cells with a high nuclear-cytoplasmic ratio. Positive staining for vimentin, alpha smooth muscle actin and CD1…
Vascularity, perfusion rate and local tissue oxygenation of tumors derived from ras-transformed fibroblasts.
2007
Tumors derived from ras-transformed rat fibroblasts were investigated in order to gain insight into possible interrelationships between oncogenic transformations and therapeutically relevant parameters of the metabolic micromilieu of solid tumors in vivo. Tumors grew in nude mice after injection of in vitro-passaged cells. Growth rates, early stages of angiogenesis, perfusion and tissue oxygenation were assessed. Compared with the parental cell line, both ras transformants grew very rapidly and exhibited an early onset of angiogenesis. Perfusion rates of one ras-transformed tumor line were similar to those of the parental tumors whereas reduced flow values were detected in tumors of the oth…
Aldehyde Dehydrogenase 1-Positive Cancer Stem Cells Mediate Metastasis and Poor Clinical Outcome in Inflammatory Breast Cancer
2009
Abstract Purpose: To examine the role of cancer stem cells (CSC) in mediating metastasis in inflammatory breast cancer (IBC) and the association of these cells with patient outcome in this aggressive type of breast cancer. Experimental Design: CSCs were isolated from SUM149 and MARY-X, an IBC cell line and primary xenograft, by virtue of increased aldehyde dehydrogenase (ALDH) activity as assessed by the ALDEFLUOR assay. Invasion and metastasis of CSC populations were assessed by in vitro and mouse xenograft assays. Expression of ALDH1 was determined on a retrospective series of 109 IBC patients and this was correlated with histoclinical data. All statistical tests were two sided. Log-rank …