Cytotoxicity radiation potentiation

Nicotinamide potentiates the cytotoxic effects of chemotherapy and radiation treatment against tumor cells. This effect is probably attributable to increased... 

Ohmori T, Arteaga C]L (1998) Protein kinase C epsilon translocation and phosphorylation by cis-diamminedichloroplatinum(II) (CDDP) potential role in CDDP-mediated cytotoxicity. Cell Growth Differ 9 345-353 Ojeda F, Guarda MI, Maldonado C, Folch H, Diehl H (1992) Role of protein kinase-C in thymocyte apoptosis induced by irradiation. Int J Radiat Biol 61 663-667 Oka M, Ogita K, Ando H, Horikawa T, Hayashibe K, Saito N, Kikkawa U, Ichihashi M (1996) Deletion of specific protein tdnase C subspecies in human melanoma cells. J Cell Physiol 167 406-412... 

Spatial cooperation is a term coined to describe a situation when disease in one particular anatomic site is missed by one modality but is treated adequately by another. The essence of this is that radiation is a local therapy that will not impact on metastatic disease beyond the planned field borders. Systemic cytotoxic chemotherapy is traditionally used to address the potential distant spread of cancer. In the original description of this mechanism there is no assumption of an interaction between the drugs and radiation with the idea being that the best radiation and best chemotherapy be administered independently of toxicities. The classic example used in several textbooks to illustrate this is the treatment of childhood leukemia with systemic chemotherapy, while their central nervous system, a potential sanctuary site where disease is not treated adequately by chemotherapy, is treated by radiation (28). The reality of the interaction between radiation and chemotherapy is that the dose and timing of radiation are adjusted accordingly to minimize their impact on the neural tissues. 

It has been postulated that radiation may act as a potentiator of fluoropyrimidine-medi-cated cytotoxicity. This possibility is borne out of the observation that fluoropyrimidine-induced radiosensitization of human colon cancer cells tends to occur under conditions that produce at least some cytotoxicity by the drug alone (15,33,36,37). This hypothesis is further supported by the data employing FdUrd treatment in HT29 cells, which showed that enhancement ratio was significantly greater when surviving fraction was <0.7 than when the surviving fraction was >0.7 (p < 0.05 by t test) (Fig. 6). 

OmuraM,TorigoeS,KubotaN. SN-38, ametabolite of the camptothecin derivative CPT-11, potentiates the cytotoxic effect of radiation in human colon adenocarcinoma cells grown as spheroids. Radiother Oncol 1997 43(2) 197-201. 

Ascorbate Potentiated Cytotoxicity of Nitroaromatic Compounds. Extensive research aimed at finding chemicals or chemical systems that will sensitize hypoxic cells, which are ordinarily very resistant to radiation or chemicals, is being conducted in the field of radiobiology. Of particular interest are the investigations (58-6J) of the catalytic effect of certain carcinogens upon the oxidation of ascorbate. 4-Nitroquinoline N-oxide (4-NQO), which is one of many compounds (52,62,63) that mediate the ascorbate-oxygen reaction, is used as an example. 

Phototoxicity or chemical phototoxicity is the term used for an acute reaction that can be induced by a single treatment with a chemical and UV or visible radiation. The basic mechanism of phototoxicity can be described as an increase in toxicity of a chemical induced by exposure to UV or visible radiation. Therefore the phototoxic potential of a chemical can be measured as an increase in cytotoxicity after exposure to UV or visible light. The 3T3 NRU PT test is a validated and robust in vitro phototoxicity test according to the criteria laid down by the ECVAM Workshop on practical aspects of the validation of toxicity test procedures and the conclusion of the ECVAM/COLIPA validation study [72], Owing to the convincing performance of the 3T3 NRU PT test, the test is now established and in use in industry laboratories to screen... 

Chaplin, D. J., Acker, B., and Olive, P. L. (1989) Potentiation of the tumor cytotoxicity of melphalan by vasodilating drugs. Inti. J. Radiat. Oncol. Biol. Phys. 16, 1131-1135. 

Lee I (2008) Ranpirnase (Onconase), a cytotoxic amphibian ribonuclease, manipulates tumour physiological parameters as a selective killer and a potential enhancer for chemotherapy and radiation in cancer therapy. Expert Opin Biol Ther 8 813-827... 

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