Cytotoxic enhancement of low dose-rate irradiation in human lung cancer cells by mild hyperthermia. 1998

H Sakurai, and N Mitsuhashi, and Y Kitamoto, and T Nonaka, and K Harashima, and K Higuchi, and H Muramatsu, and T Ebara, and H Ishikawa, and H Niibe
Department of Radiology and Radiation Oncology, Gunma University School of Medicine, Japan. hsakurai@sb.gunma-u.ac.jp

OBJECTIVE The aim of this study was to investigate the cell killing induced by low dose-rate irradiation (LDRI) simultaneously combined with long duration mild hyperthermia in LK87 human lung cancer cells. Cell cycle alteration due to this combined treatment was also observed. METHODS Human lung adenocarcinoma cells, LK87, were treated with concurrent LDRI (50 cGy/hr) and mild hyperthermia (38 to 42 degrees C). Cell survival was estimated by clonogenic assay. Flow cytometry was performed with FACScan. The treatments were simultaneously performed for up to 48 hr (24 Gy). RESULTS Survival curves of mild hyperthermia alone revealed development of chronic thermotolerance up to 48 hr, whereas LDRI plus hyperthermia caused an exponential decrease in survival. The LDRI cytotoxicities were enhanced by mild hyperthermia over a non-lethal temperature range. The Do values calculated from dose response curves at 37, 38, 39, 40, 41 41.5 and 42 degrees C were 6.55, 5.25, 4.24, 3.99, 3.46, 1.83 and 0.70 Gy, respectively. Cell cycle analysis demonstrated a remarkable G2 and a mild G1 block for LDRI alone, but only a G1 block was observed for LDRI combined with 41 degrees C hyperthermia. CONCLUSIONS The LDRI cytotoxicity was enhanced by long duration mild temperature hyperthermia. The suppression of chronic thermotolerance was considered to be a mechanism involved in this sensitization.

UI MeSH Term Description Entries
D006979 Hyperthermia, Induced Abnormally high temperature intentionally induced in living things regionally or whole body. It is most often induced by radiation (heat waves, infra-red), ultrasound, or drugs. Fever Therapy,Hyperthermia, Local,Hyperthermia, Therapeutic,Thermotherapy,Induced Hyperthermia,Therapeutic Hyperthermia,Therapy, Fever,Local Hyperthermia
D008175 Lung Neoplasms Tumors or cancer of the LUNG. Cancer of Lung,Lung Cancer,Pulmonary Cancer,Pulmonary Neoplasms,Cancer of the Lung,Neoplasms, Lung,Neoplasms, Pulmonary,Cancer, Lung,Cancer, Pulmonary,Cancers, Lung,Cancers, Pulmonary,Lung Cancers,Lung Neoplasm,Neoplasm, Lung,Neoplasm, Pulmonary,Pulmonary Cancers,Pulmonary Neoplasm
D002470 Cell Survival The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability. Cell Viability,Cell Viabilities,Survival, Cell,Viabilities, Cell,Viability, Cell
D002588 Cesium Radioisotopes Unstable isotopes of cesium that decay or disintegrate emitting radiation. Cs atoms with atomic weights of 123, 125-132, and 134-145 are radioactive cesium isotopes. Radioisotopes, Cesium
D004273 DNA, Neoplasm DNA present in neoplastic tissue. Neoplasm DNA
D004307 Dose-Response Relationship, Radiation The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation. Dose Response Relationship, Radiation,Dose-Response Relationships, Radiation,Radiation Dose-Response Relationship,Radiation Dose-Response Relationships,Relationship, Radiation Dose-Response,Relationships, Radiation Dose-Response
D005434 Flow Cytometry Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake. Cytofluorometry, Flow,Cytometry, Flow,Flow Microfluorimetry,Fluorescence-Activated Cell Sorting,Microfluorometry, Flow,Cell Sorting, Fluorescence-Activated,Cell Sortings, Fluorescence-Activated,Cytofluorometries, Flow,Cytometries, Flow,Flow Cytofluorometries,Flow Cytofluorometry,Flow Cytometries,Flow Microfluorometries,Flow Microfluorometry,Fluorescence Activated Cell Sorting,Fluorescence-Activated Cell Sortings,Microfluorimetry, Flow,Microfluorometries, Flow,Sorting, Fluorescence-Activated Cell,Sortings, Fluorescence-Activated Cell
D006358 Hot Temperature Presence of warmth or heat or a temperature notably higher than an accustomed norm. Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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