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Micro-Raman technique can be particularly useful to investigate the chemical changes induced in structure, protein, nucleic acid, lipid, and carbohydrate contents of cells. The aim of this work is to inspect the possibility to employ Raman microspectroscopy to detect biochemical modifications in human mammary epithelial cells after exposure to different Xray doses. The samples consisted of cells cultured on polylysine-coated glass coverslips. After the exposition, control and treated cells were washed in phosphate-buffered saline (PBS) and then fixed in paraformaldehyde 3.7%. They were examined using a confocal micro-Raman system equipped with a He-Ne laser ( = 632.8 nm; power on the sample= 3.5mW). Differences in the intensity ratio of specific Raman vibrational markers commonly assigned to phenylalanine and tyrosine amino acids (at 1000, 1030, 1618 cm-1), DNA bases (787, 1090, 1305 cm-1), and amide III (1237, and 1265 cm-1) with respect a reference peak (the one of lipids at 1450 cm-1) were evidenced between control and exposed cells. These differences may be indicative of damage in exposed cells as the fragmentation of individual amino acids and DNA bases, crosslink effects in molecular structure of DNA and protein conformational change that especially tend to "unwind" the protein due to the breaking of hydrogen bonds between peptide chains.

Non-cancer biological effects of ionising radiation exposure are of relevance for estimating normal tissue damage arising from radiotherapy as well as for space radiation protection. In particular, as ion-based radiation treatment of cancer is looking increasingly promising, it is necessary to investigate whether charged particles such as carbon ions, whose increased biological effectiveness at causing early cytotoxicity in the form of clonogenic death is well known, are also more effective than photons at inducing late effects, thereby obscuring their beneficial anti-cancer potential. Aside from neoplastic transformation, one such late effect is cellular senescence, which has been shown to be inducible in vitro by a variety of stressors, including ionising radiation at sub-lethal doses. Such a response, termed stress-induced premature senescence (SIPS), manifests itself as a senescent-like phenotype but, unlike physiological loss of reproductive ability, which serves as a tumour repressor mechanism leading to death or terminal differentiation, is not unambiguously linked with telomere length attrition. In fact, SIPS, while enabling the damaged cell to escape radiation-induced death, can be enacted by damage-response pathways. This may ultimately lead to genome instability and hence transformation. In vivo, accumulation of prematurely senescent cells in a normal tissue can impact its performance and accelerate its degeneration. In order to study the dependence of SIPS upon radiation quality and to examine whether it is mechanistically linked with reduced telomere length, we exposed a model system (human vein endothelial cells) to the GSI carbon ion beam, used for therapeutic purposes, at both the LET values incurred by normal (plateau region) and tumour (spread-out Bragg Peak) cells. X-ray irradiation was used as a reference. The onset of cellular senescence was studied by beta-galactosidase expression in the progeny of irradiated or control cells and related to measurements of telomere length. The latter was performed by means of an automated system that allows recognition of interphase cells labelled by a pan-telomeric fluorescent probe and a centromere-directed probe (IQ-FISH). Relative telomere length was obtained by the fluorescence intensity ratio between the two markers. Our data suggest that ionising radiation causes surviving descendants to enter senescence earlier than their sham-irradiated counterparts, exhibiting a complex dependence upon LET and a non-linear correlation with telomere length reduction.

Non-cancer biological effects of ionising radiation exposure are of relevance for estimating normal tissue damage arising from radiotherapy as well as for space radiation protection. In particular, as ion-based radiation treatment of cancer is looking increasingly promising, it is necessary to investigate whether charged particles such as carbon ions, whose increased biological effectiveness at causing early cytotoxicity in the form of clonogenic death is well known, are also more effective than photons at inducing late effects, thereby obscuring their beneficial anti-cancer potential. Aside from neoplastic transformation, one such late effect is cellular senescence, which has been shown to be inducible in vitro by a variety of stressors, including ionising radiation at sub-lethal doses. Such a response, termed stress-induced premature senescence (SIPS), manifests itself as a senescent-like phenotype but, unlike physiological loss of reproductive ability leading to death or terminal differentiation that it resembles, is not unambiguously linked with telomere length attrition and can be reversed. Thus, it is possible that SIPS, while representing an escape from radiation-induced death, may be enacted by damage-response pathways and lead ultimately to genome instability and hence transformation. In vivo accumulation of prematurely senescent cells in a normal tissue can impact its performance and accelerate degenerative effects. In order to study the dependence of SIPS upon radiation quality and to examine its mechanistical link with reduced telomere length, we exposed a widely used model system (human vein endothelial cells) to the GSI carbon ion beam at both the LET values incurred by normal (plateau region) and tumour (spread-out Bragg Peak) cells. X-ray irradiation was used as a reference. The onset of cellular senescence was studied in the progeny of irradiated or control cells and related to measurements of telomere length. The latter was performed by means of an automated system that allows recognition of interphase cells labelled by a pan-telomeric fluorescent probe and a centromere-directed probe (IQ-FISH). Relative telomere length was obtained by the fluorescence intensity ratio between the two markers. Our data suggest that ionising radiation causes surviving descendants to enter senescence earlier than do their unirradiated counterparts, exhibiting a complex dependence upon increasing LET values and a non-linear correlation with telomere length reduction.