title: Inactivation of HTB63 human melanoma cells by irradiation with protons and gamma rays.
abstract: The effects of single irradiation with gamma rays and protons on HTB63 human melanoma cell growth were compared. The exponentially growing cells were irradiated with gamma rays or protons using doses ranging from 2-20 Gy. At 48 h of post-irradiation incubation under standard conditions, cell survival and induction of apoptotic cell death were examined. The best effect of the single irradiation with gamma rays was the reduction of cell growth by up to 26% (p=0.048, irradiation vs. control), obtained using the dose of 16 Gy. The same doses of proton irradiation, having energy at the target of 22.6 MeV, significantly inhibited melanoma cell growth. Doses of 12 and 16 Gy of protons provoked growth inhibition of 48.9% (p=0.003, irradiation vs. control) and 51.2% (p=0.012, irradiation vs. control) respectively. Irradiation with 12 and 16 Gy protons, compared to the effects of the same doses of gamma rays, significantly reduced melanoma cell growth (p=0.015 and p=0.028, protons vs. gamma rays, respectively). Estimated RBEs for growth inhibition of HTB63 cells ranged from 1.02 to 1.45. The electrophoretical analyses of DNA samples and flow cytometric evaluation have shown a low percentage of apoptotic cells after both types of irradiation. The better inhibitory effect achieved by protons in contrast to gamma rays, can be explained considering specific physical properties of protons, especially taking into account the highly localized energy deposition (high LET).
authors.affiliation: Vinca Institute of Nuclear Sciences, Laboratory for Molecular Biology and Endocrinology, 11001 Belgrade, Serbia and Montenegro. aristic@rt270.vin.bg.ac.yu
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ristic-Fira
authors.forename: Ivan
authors.initials: I
authors.lastname: Petrovic
authors.forename: Danijela
authors.initials: D
authors.lastname: Todorovic
authors.forename: Lela
authors.initials: L
authors.lastname: Koricanac
authors.forename: Miroslava
authors.initials: M
authors.lastname: Vujèic
authors.forename: Miroslav
authors.initials: M
authors.lastname: Demajo
authors.forename: Gabriella
authors.initials: G
authors.lastname: Sabini
authors.forename: Pablo
authors.initials: P
authors.lastname: Cirrone
authors.forename: Giacomo
authors.initials: G
authors.lastname: Cuttone
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D004587:Electrophoresis, Agar Gel; D005434:Flow Cytometry; D005720:Gamma Rays; D006801:Humans; D008545:Melanoma / Q000378:metabolism; D011522:Protons; D011874:Radiometry; D012062:Relative Biological Effectiveness; D013534:Survival
chemical_list: D011522:Protons