Irradiation and various cytotoxic drugs enhance tyrosine phosphorylation and beta(1)-integrin clustering in human A549 lung cancer cells in a substratum-dependent manner in vitro.

Background And Purpose: Interactions of cells with a substratum, especially extracellular matrix proteins, initiate clustering of integrin receptors in the cell membrane. This process represents the initial step for the activation of signaling pathways regulating survival, proliferation, differentiation, adhesion, and migration, and could, furthermore, be important for cellular resistance mediating mechanisms against radiation or cytotoxic drugs. The lack of data elucidating the impact of irradiation or cytotoxic drugs on this important phenomenon led to this study on human A549 lung cancer cells in vitro.

Development and evaluation of a skin organ model for the analysis of radiation effects.

Background And Purpose: The reaction of tissues to ionizing radiation involves alterations in cell-cell and cell-matrix interactions mediated by cellular adhesion molecules. The aim of this study was to develop and evaluate an artificial skin organ model for the analysis of radiation effects.

Material And Methods: A human co-culture system consisting of the spontaneously immortalized keratinocyte cell line HaCaT and primary HDFa fibroblasts embedded into a collagen sponge was established.

Arrest of human lung fibroblasts in G2 phase after irradiation is regulated by converging phosphatidylinositol-3 kinase and beta1-integrin signaling in vitro.

Purpose: Cell-matrix interactions might confer cellular radioresistance in vitro. As a function of radiation, the impact of fibronectin (FN) and phosphatidylinositol-3 kinase (PI3K)-related signaling on survival, the cell cycle, and the beta1-integrin signaling kinases integrin-linked kinase (ILK), protein kinase Balpha/Akt (PKBalpha/Akt), and glycogen synthase kinase-3beta (GSK-3beta) was examined in normal lung fibroblasts in vitro.

Methods And Materials: Normal human CCD32 lung fibroblasts grown on polystyrene, FN, or poly-L-lysine were irradiated with 0-8 Gy.

Comparison of endogenous TP53 genomic status with clonogenicity and different modes of cell death after X irradiation.

Although extensive data indicate that the tumor suppressor TP53 modifies the radiation responses of human and rodent cells, the exact relationship between TP53 and radiation responsiveness remains controversial. To elucidate the relevance of endogenous TP53 genomic status to radiosensitivity in a cell-type-independent manner, different cells of 10 human tumor cell lines with different tissues of origin were examined for TP53 status. The TP53 status was compared with radiation-related cell survival parameters (D(q), D(0), SF2) and with the mode of cell death.

Modulation of X-ray-induced apoptosis in human keratinocytes (HaCaT) by 1,25-dihydroxyvitamin D3.

Possible effects of 1,25-dihydoxyvitamin D3 (vitamin D) on ionizing radiation-induced cell damage have been unknown until now. The task of the present study was to analyze, in a human keratinocyte cell line (HaCaT), the effects of a preincubation with vitamin D on the X-ray-induced mRNA expression of different genes related to apoptosis (gene array). The first results show that ionizing radiation leads to a down-regulation of various apoptosis-relevant genes in HaCaT cells pretreated with vitamin D.

Medical management principles for radiation accidents.

The medical management of radiation accidents requires intensive planning and action. This article looks at the medical management of recent radiation accidents to derive principles for structuring and organizing the treatment of patients who may have radiation-induced health impairments. Although the radiation accidents in Tokai-mura, Japan and Lilo, Georgia were small-scale accidents, they illustrate important and characteristic symptoms and clinical developments.

Ionizing radiation modulates cell surface integrin expression and adhesion of COLO-320 cells to collagen and fibronectin in vitro.

Purpose: Adhesion of tumor cells to endothelial cells and to the extracellular matrix is a key step in the initial phase of metastasis. Since radiotherapy of tumors can induce alterations of the cell surface, we investigated the effect of ionizing radiation on the expression of integrins in the colorectal tumor cell line COLO-320 and the modulation of adhesion capacity of irradiated cells to collagen and fibronectin.

Material And Methods: The cell surface expression of a broad range of integrins on COLO-320 cells was determined by flow cytometry during 144 hours after X-irradiation.

Fas/Fas ligand system and apoptosis induction in testicular carcinoma.

Background: Tumor-infiltrating, Fas ligand (FasL)-expressing lymphocytes are able to eliminate Fas-bearing tumor cells by apoptosis induction. Activated cytotoxic T-cells that express Fas may enter apoptosis in the presence of FasL tumor cells. To date, no studies of patients with testicular carcinoma have correlated the differential expression of Fas and FasL in both cell types with the corresponding apoptotic index (AI).