Bystander Me45 Melanoma Cells Increase Damaging Effect in UVC-irradiated Cells.

The aim of our study was to investigate the possible mechanism(s) of the bystander effect induced by UVC light in malignant melanoma Me45 cells that were co-incubated with irradiated cells of the same line. We have found that the UVC band effectively generated apoptosis, premature senescence, single and double DNA strand breaks and reduced clonogenic survival of bystander cells. However, in the feedback response, the bystander cells intensified damage in directly irradiated cells, especially seen at the level of apoptosis and survival of clonogenic cells.

Modulation by neighboring cells of the responses and fate of melanoma cells irradiated with UVA.

UVA radiation, which accounts for about 95% of the solar spectrum, contributes to and may be the etiological factor of skin cancers of which malignant melanoma is the most aggressive. UVA causes oxidative stress in various types of cells in the skin, keratinocyte, melanocytes, and fibroblasts, which is responsible for its cytotoxic effect. Here we used a transwell system to explore how the responses of melanoma cells to a low dose of UVA (20kJ/m, ~10% of the minimal erythema dose) are influenced by neighboring co-cultured melanoma cells or fibroblasts.

The different radiation response and radiation-induced bystander effects in colorectal carcinoma cells differing in p53 status.

Radiation-induced bystander effect, appearing as different biological changes in cells that are not directly exposed to ionizing radiation but are under the influence of molecular signals secreted by irradiated neighbors, have recently attracted considerable interest due to their possible implication for radiotherapy. However, various cells present diverse radiosensitivity and bystander responses that depend, inter alia, on genetic status including TP53, the gene controlling the cell cycle, DNA repair and apoptosis. Here we compared the ionizing radiation and bystander responses of human colorectal carcinoma HCT116 cells with wild type or knockout TP53 using a transwell co-culture system.

Connecting radiation-induced bystander effects and senescence to improve radiation response prediction.

For the last two decades radiation-induced bystander effects (RIBEs) have attracted significant attention due to their possible implications for radiotherapy. However, despite extensive research, the molecular pathways associated with RIBEs are still not completely known. In the current study we investigated the role of senescence in the bystander response.

Induction of bystander effects by UVA, UVB, and UVC radiation in human fibroblasts and the implication of reactive oxygen species.

Radiation-induced bystander effects are various types of responses displayed by nonirradiated cells induced by signals transmitted from neighboring irradiated cells. This phenomenon has been well studied after ionizing radiation, but data on bystander effects after UV radiation are limited and so far have been reported mainly after UVA and UVB radiation. The studies described here were aimed at comparing the responses of human dermal fibroblasts exposed directly to UV (A, B, or C wavelength range) and searching for bystander effects induced in unexposed cells using a transwell co-incubation system.

The influence of XPD, APE1, XRCC1, and NBS1 polymorphic variants on DNA repair in cells exposed to X-rays.

Polymorphism of genes coding for proteins which participate in DNA repair may predispose to or protect against development of cancer. Here we studied how common polymorphisms of the genes XPD (Asp312Asn and Lys751Gln), APE1 (Asp148Glu), XRCC1 (Arg399Gln), and NBS1 (Gln185Glu) influence DNA repair and other responses after X-irradiation of lymphocytes from colon carcinoma patients. Genotypes with polymorphic Asp148Glu APE1 and Asp312Asn XPD showed a significantly higher level of DNA incisions immediately after irradiation (p=0.

Bystander effect induced by UV radiation; why should we be interested?

The bystander effect, whose essence is an interaction of cells directly subjected to radiation with adjacent non-subjected cells, via molecular signals, is an important component of ionizing radiation action. However, knowledge of the bystander effect in the case of ultraviolet (UV) radiation is quite limited. Reactive oxygen and nitrogen species generated by UV in exposed cells induce bystander effects in non-exposed cells, such as reduction in clonogenic cell survival and delayed cell death, oxidative DNA damage and gene mutations, induction of micronuclei, lipid peroxidation and apoptosis.

Bystander normal human fibroblasts reduce damage response in radiation targeted cancer cells through intercellular ROS level modulation.

The radiation-induced bystander effect is a well-established phenomenon which results in damage in non-irradiated cells in response to signaling from irradiated cells. Since communication between irradiated and bystander cells could be reciprocal, we examined the mutual bystander response between irradiated cells and co-cultured with them non-irradiated recipients. Using a transwell culture system, irradiated human melanoma (Me45) cells were co-cultured with non-irradiated Me45 cells or normal human dermal fibroblasts (NHDF) and vice versa.

Ionizing radiation-induced bystander effects, potential targets for modulation of radiotherapy.

Cells exposed to ionizing radiation show DNA damage, apoptosis, chromosomal aberrations or increased mutation frequency and for a long time it was generally accepted that these effects resulted from ionization of cell structures and the action of reactive oxygen species formed by water radiolysis. In the last few years, however, it has appeared that cells exposed to ionizing radiation and other genotoxic agents can release signals that induce very similar effects in non-targeted neighboring cells, phenomena known as bystander effects. These signals are transmitted to the neighboring non-hit cells by intercellular gap-junction communication or are released outside the cell, in the case of cultured cells into the medium.

[Radiation-induced bystander effect: the important part of ionizing radiation response. Potential clinical implications].

It has long been a central radiobiological dogma that the damaging effects of ionizing radiation, such as cell death, cytogenetic changes, apoptosis, mutagenesis, and carcinogenesis, are the results of the direct ionization of cell structures, particularly DNA, or indirect damage via water radiolysis products. However, several years ago attention turned to a third mechanism of radiation, termed the "bystander effect" or "radiation-induced bystander effect" (RIBE). This is induced by agents and signals emitted by directly irradiated cells and manifests as a lowering of survival, cytogenetic damage, apoptosis enhancement, and biochemical changes in neighboring non-irradiated cells.

X-irradiation and bystander effects induce similar changes of transcript profiles in most functional pathways in human melanoma cells.

Unirradiated cells which neighbor cells exposed to ionizing radiation (IR) show responses termed bystander effects, including DNA damage, chromosomal instability, mutation, and apoptosis. We used genome-wide microarrays to compare the change in transcript profiles in Me45 (human melanoma) cells grown in culture medium from irradiated cells (irradiation conditioned medium, ICM) with those which occurred after IR, sampling after more than one division cycle to detect long-term changes which could be relevant in radiotherapy. Transcripts of >10,000 genes showed an increased or decreased level in both conditions using the criterion of a >+/-10% change, and >85% of these were common to growth in ICM and after IR.

[Dose rate-dependent cellular and molecular effects of ionizing radiation].

The aim of radiation therapy is to kill tumor cells while minimizing damage to normal cells. The ultimate effect of radiation can be apoptotic or necrotic cell death as well as cytogenetic damage resulting in genetic instability and/or cell death. The destructive effects of radiation arise from direct and indirect ionization events leading to peroxidation of macromolecules, especially those present in lipid-rich membrane structures as well as chromatin lipids.

[Mechanisms of metastasis and molecular markers of malignant tumor progression. I. Colorectal cancer].

The ability of neoplastic cells to dissemination from a primary tumor to lymphatic nodes and to adjacent and distant tissues and organs is an inseparable feature of malignant tumors and the main cause of failure in their treatment. Metastasis formation is a multistage process which includes proteolysis, the motility and migration of cells, proliferation, and neoangiogenesis. In the first step, the cells released from the primary tumor have to penetrate to the blood or lymphatic vessels (intravasation), the road which dissemination follows.

[Cardiotoxic consequences of ionizing radiation and anthracyclines].

The mechanisms of the toxic side effects of radiation and anthracyclines are generally based on free radical reactions. Target molecules for free radicals are not only DNA and proteins, but also membrane structures abundant in phospholipids. Cardiomyocyte membrane lipid peroxidation may consequently lead to structural and functional damage.

Spectroscopic properties and photodynamic effects of new lipophilic porphyrin derivatives: efficacy, localisation and cell death pathways.

Photodynamic therapy (PDT) and photodynamic diagnostics (PDD) of cancer are based on the use of non-toxic dyes (photosensitisers) in combination with harmless visible light. This paper reports physicochemical properties, cell uptake, localisation as well as photodynamic efficiency of two novel lipophilic porphyrin derivatives, suitable for use as PDT sensitisers. Both compounds are characterised by high quantum yield of singlet oxygen generation which was measured by time-resolved phosphorescence.

Protective effect of local temporary ischemia depends on applied dose of radiation.

The aim of this study was to verify hypothesis that protective effect of local temporary ischemia depends on dose of radiation. 56 male WAG-strain rats were used. Total body irradiation with 3 x 3 and 3 x 5 Gy was performed.

Cell proliferative activity estimated by histone H2B mRNA level correlates with cytogenetic damage induced by radiation in human glioblastoma cell lines.

We studied the relationship between proliferative activity and radiation-induced DNA damage in human malignant gliomas in vitro. Nine human glioblastoma established cell lines were gamma-irradiated (60Co) over a dose range of 0-10 Gy. H2B and H4 histone mRNA level was assessed with quantitative RT-PCR technique (TaqMan) and histone labeling index (HLI) with in situ hybridization to define proliferation rate, while cytochalasin-block micronucleus assay was performed to measure cytogenetic damage.

Multiple bystander effect of irradiated megacolonies of melanoma cells on non-irradiated neighbours.

The multicellular megacolonies of human melanoma Me45 line growing on one part of the bottom of culture flasks were irradiated with 5 Gy (60Co), whereas megacolonies growing on the second part of the bottom were shielded. The bystander effect of radiation-traversed cells on non-traversed cells was studied during postradiation co-cultivation. Activity of superoxide dismutase (Mn and CuZn subunits), glutathione peroxidase (GSH-Pox) and malondialdehyde (MDA) concentration as a biochemical markers of bystander effect were monitored for a period of 72 h.

Photodynamic effects of two water soluble porphyrins evaluated on human malignant melanoma cells in vitro.

Two water soluble porphyrins: meso-tetra-4-N-methylpyridyl-porphyrin iodide (P1) and 5,10-di-(4-acetamidophenyl)-15,20-di-(4-N-methylpyridyl) porphyrin (P2) were synthesised and evaluated in respect to their photochemical and photophysical properties as well as biological activity. Cytotoxic and phototoxic effects were evaluated in human malignant melanoma Me45 line using clonogenic assay, cytological study of micronuclei, apoptosis and necrosis frequency and inhibition of growth of megacolonies. Both porphyrins were characterised by high UV and low visible light absorptions.

Apoptosis and clonogenic survival in three tumour cell lines exposed to gamma rays or chemical genotoxic agents.

We compared the extent to which apoptosis is induced and clonogenicity reduced in three tumour cell lines - the human melanoma Me45 and promyelocytic leukaemia HL-60, and the rat rhabdomyosarcoma R1 - after exposure to the anticancer drugs etoposide and cis-platinum or to gamma radiation; each induces different types of DNA damage. Cells which readily underwent apoptosis did not necessarily show a correlated loss of clonogenicity; for example, Me45 cells showed the highest sensitivity to all three agents in clonogenic assays but much lower levels of apoptotic cells than R1 or HL-60 cells. These results show that the efficiency of the eradication of clonogenic cells by genotoxic agents does not solely depend on the induction of apoptotic processes, and suggest that the induction of apoptosis and suppression of clonogenicity are independent processes.

Radiation-induced micronucleus frequency in peripheral blood lymphocytes is correlated with normal tissue damage in patients with cervical carcinoma undergoing radiotherapy.

In an effort to find a test to predict the response of normal tissue to radiotherapy, the lymphocyte micronucleus assay was used on blood samples from patients with cervical carcinoma. Peripheral blood samples from 55 patients with advanced-stage (II B-IV B) cervical carcinoma were obtained before radiotherapy. The patients were treated with external-beam radiotherapy followed by high-dose-rate brachytherapy.

Inhibitory effect of local ischaemic preconditioning in total body irradiated rats.

The aim of this study was to explore the relationship between local ischaemic preconditioning and the effectiveness of fractionated radiotherapy. The rat serum, bone marrow, and small intestine were examined for oxidative changes induced by total body irradiation with gamma rays with applied local ischaemic preconditioning immediately before irradiation. Serum concentrations of TBA-RS examined 12 hours after the last irradiation did not reveal any differences among the groups of animals analyzed.

Tumor cell repopulation during conventional and accelerated radiotherapy in the in vitro megacolony culture.

Purpose: To analyze the repopulation rate of cancer cells in vitro during conventional and accelerated irradiation, using the megacolony culture.

Materials And Methods: Two cell lines-murine squamous cell carcinoma AT478 and human adenocarcinoma A549-were grown as epithelial megacolonies in vitro, and they were irradiated using Co-60 gamma source at the dose rate of 0.82 Gy/min.

[Fatty acids as a potentially helpful supplement in cancer therapy].

This review presents pro- and anticancer effects of fatty acids in vitro and in vivo. The epidemiological and experimental data indicate that short-chain saturated and long-chain unsaturated omega-3 fatty acids exert protective effects against some cancers. In the contrary, omega-6 fatty acids are rather procancerous and can increase tumour proliferation.

Radiation-induced DNA damage and its repair in lymphocytes of patients with head and neck cancer and healthy donors.

Background: DNA repair capacity may be an important factor in determining both individual susceptibility to cancer and the response to cancer therapy. The aim of this work was to compare DNA damage and the repair process in cells originating from healthy donors and cancer patients.

Materials And Methods: Using the micronucleus and comet assays, we compared the induction of DNA damage and its repair in lymphocytes isolated from blood samples of 14 healthy donors and 24 patients with head and neck tumours.