Proliferation capacity and p53 expression of HTB140 cells after proton irradiation

Human HTB140 melanoma cells were used to investigate different responses to single irradiation with protons, regarding cell proliferation, induction of apoptosis and expression of p53. Exponentially growing cells were irradiated close to the Bragg peak maximum of the unmodulated 62 MeV proton beam. Doses applied ranged from 8 to 24 Gy at the dose rate of 15 Gy/min. Cell proliferation, measured 6 and 48 h postirradiation, has shown highly significant dose and time dependent decrease. Protons induced apoptosis, 6 and 48 h after irradiation, decreasing with the increase of postirradiation incubation time. The largest number of apoptotic cells was at 6 h after irradiation with 16 Gy protons. High level of p53 expression was detected in all irradiated samples, as well as in controls and was independent of dose applied and postirradiation incubation time.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Effects of short time exposure of HTB140 melanoma cells to fotemustine and dacarbazine

Different experimental set-ups were designed to study cytotoxic and cytoststic effects on HTB140 melanoma cells after 1 h treatment with fotemustine (FM) or dacarbazine (DTIC). FM induced dose dependent cell inactivation, boosted by its toxicity, particularly for higher doses. DTIC treatment for 1 h was insufficient to provoke almost any effect on melanoma cells. Good correlation between viability and proliferation assays applied was detected for both drugs.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Changes of c-myc expression in b16 melanoma cells induced by 8-chloroadenosine-3′, 5′-monophosphate and tiazofurin

The aim of this study was to investigate the in vitro effects of 8- chloroadenosine 3′, 5′-monophosphate (8-Cl-cAMP) and tiazofurin (TR) on the expression of c-myc gene in B16/F10 and B16/C3 mouse melanoma cells. Exponentially growing cells were treated with 8-Cl-cAMP or TR (5µmol - 25µmol) for 6h and 24h. The level of c-myc expression, estimated by RT-PCR, did not significantly change in B16/F10 cells after treatment with 8-Cl-cAMP or TR. Similar results were obtained in B16/C3 cells after treatment with 8-Cl-cAMP. The level of c-myc expression has shown a significant increase in B16/C3 cells after treatment with TR. Further studies of these agents will lead to better understanding of molecular mechanisms of their action.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Sensitivity of HTB140 cell exposed to protons and alkylating agents

Malignant melanoma is a highly aggressive cancer with a poor prognosis due to resistance to radiotherapy and chemotherapy regimens. The mainstay of treatment remains DNA-alkylatingagent dacarbazine (DTIC). Fotemustine (FM), chloroethylnitrosourea agent, also has demonstrated significant antitumoral effects in malignantmelanoma. However, the resistance of melanoma cells limits their clinical application. In order to enhance the inhibition of melanoma cell growth, in this study, combined treatment of FM and DTIC with proton irradiation, was investigated. We analyzed the effects of combined treatment on HTB140 melanoma cell viability and proliferation. Significant inhibition of cell growth, especially cell proliferation, was obtained after treatment with protons and FM compare to single irradiation or drug treatment. Treatment with protons and DTIC has shown improved growth inhibition compare to appropriate single drug treatment, but not compare to irradiation as a single treatment.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Analysis of nuclear glucocorticoid receptor-DNA interaction in aged rat liver

Abstract: In order to contribute to the understanding of mechanisms by which regulatory proteins recognize genetic information stored in DNA, analyses of their interaction with specific nucleotides are usually performed. In this study, the electrophoretic mobility shift assay (EMSA) was applied to analyze the interaction of nuclear proteins from the liver of rats of different age i.e., young (3-month-old), middle- aged (12-month-old) and aged (24-month-old), with radioactively labelled synthetic oligonucleotide analogues, corresponding to GRE. The levels of GRE binding activity were assessed by quantitative densitometric scanning of the autoradiograms. The results showed statistically significant decreasing values of up to 78% and 49% in middle aged and old animals, respectively, compared to young animals (p < 0.05). The specificity of the nuclear proteins-GRE interaction was demonstrated by competition experiments with unlabelled GRE. In a supershift assay, using the antibody BuGR2, it was shown that the GR proteins present in nuclear extracts have a high affinity for the GRE probe. The stabilities of the protein-DNA complexes were analysed and it was concluded that they changed during ageing.U cilju doprinosa razumevanju mehanizama pomoću kojih regulatorni proteini prepoznaju genetičku informaciju koju nosi DNK, analiziraju se njihove interakcije sa specifičnim nukleotidima. U ovom radu je metodom EMSA analizirana interakcija jedarnih proteina iz jetri pacova iz tri starosne grupe (mladi - 3 meseca, srednje doba – 12 meseci i stari – 24 meseca) sa sintetičkim, radioaktivno obeleženim, oligonukleotidnim analogom GRE. Nivo vezujuće aktivnosti GRE je određivan kvantitativno denzitometrijskom autoradiografijom. Rezultati su pokazali da postoji statistički značajan pad vrednosti GRE-vezujuće aktivnosti do 78% kod životinja srednjeg starosnog doba i do 49 % kod starih životinja, u poređenju sa vrednostima dobijenim za mlade životinje (p < 0.05). Specifičnost interakcije jedarnih proteina i GRE je određena eksperimentima kompeticije sa neobeleženim GRE. Korišćenjem antitela BuGR2 pokazano je da je glukokortikoidni receptor protein koji u jedarnom ekstraktu ima najveći afinitet za GRE probu. Analizirana je stabilnost kompleksa protein-DNK i zaključeno je da se menja tokom starenja.nul

Early effects of gamma rays and protons on human melanoma cell viability and morphology

The effects of irradiation with gamma rays and protons on HTB140 human melanoma cell morphology and viability were analyzed. Exponentially growing cells were irradiated close to the Bragg peak maximum of the 62-MeV proton beam, as well as with (60)Co gamma rays, with doses ranging from 8 to 24 Gy. The overall cell morphology was unchanged 6 and 48 h after gamma irradiation, also showing a relatively weak cell-inactivation level. After exposure to proton beam, considerable changes in cell morphology followed by stronger cell inactivation were achieved. Proliferation capacity of irradiated cells significantly decreased in both experimental set-ups. Higher ionization level of protons with respect to gamma rays, representing the main physical difference between these two types of radiation, was also revealed on the cell membrane level through larger pro-apoptotic capacity of protons

Radiobiological studies on the 62 MeV therapeutic proton beam at lns catania: I. survival of HTB140 melanoma cells

The aim of this study was to determine the initial inactivation of cells induced by high-energy proton beam designed for the treatment of eye melanoma. Exponentially growing HTB140 cells were exposed to an unmodulated 62 MeV proton beam delivered over the single dose range from 8 Gy to 24 Gy. Position of samples was in the zone of the Bragg peak, having high LET values. Surviving fractions were evaluated at 6, 24 and 48 h post-irradiation. The survival curves exhibited a well-known shoulder, decreasing for doses higher than 8 Gy. Therefore, a significant dose dependent early cell inactivation after single delivery of 16 Gy to 24 Gy to the cell monolayer was observed. With the increase of the post-irradiation incubation time, a better killing effect, as the consequence of clonogenic survival, was detected.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Radiobiological studies on the 62 MeV therapeutic proton beam at lns catania: II. facs analyses of HTB140 melanoma cells

The objective of this study was to determine whether apoptosis and cell cycle redistribution were influenced by high-LET irradiation. Exponentially growing HTB140 cells were exposed to an unmodulated 62 MeV proton beam, within the Bragg peak, delivered over the single dose range from 8 Gy to 24 Gy. At 6 h post-irradiation, there was a low level of early apoptosis. At 48 h irradiated cells were more damaged, showing the increase in number of apoptotic nuclei. The dose dependent cell cycle phase distribution was detected at 48 h post-irradiation. The cell population exhibited phase redistribution toward G2/M phase.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Response of Human HTB140 Melanoma Cells to Conventional Radiation and Hadrons

Conventional radiotherapy with X-and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance

Response of Human HTB140 Melanoma Cells to Conventional Radiation and Hadrons

Conventional radiotherapy with X-and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance