| Part1. Radio-sensitivity study of RAT-1, the rat prostate cancer cell line, irradiated with Carbon ion beam (C12) under hypoxiaObjective:To investigate the radio-sensitivity of RAT-1irradiated with photon (X-ray) and carbon ion (C12) under oxic condition or hypoxia.Materials&methods:The hypoxia conditions in this study were established by two instruments-hypoxia incubator&hypoxia chamber (GSI patent), from which the acute hypoxia (0.5%Oxygen) as well as chronic hypoxia (24hours) were well mainteined according to the standard protocol at GSI respectively. The RAT-1cells in the exponential phase were irradiated with X-ray and Carbon ion beam under hypoxia and then the clonogenic formation assays were performed referring to the previous experiments in biophysic department at GSI. The survival curves under oxic condition and hypoxia were drawn with the calculated survival fractions and were fitted with Linear-Quadratic formula (L-Q model) thereafter.Results:The physical doses of Carbon ion irradiation were much lower than photon radiation at the equally survival levels in the clonogenic formation assays under oxia&hypoxia that at the10%survival level in the survival curves fitted with the linear-quadratic formula the RBE of Carbon ion was about2.6(7.1Gy divided by2.8Gy) in the experiment with hypoxia incubator. Similarly, the RBE of carbon ion in the study with hypoxia chamber was about2.1; Furthermore, the oxygen enhancement ratios (OER) of Carbon ion in the two experiments (hypoxia incubator&hypoxia chamber) were both much smaller than that of X-ray definitely (=1or-1Vs>1).Conclusions:Carbon ion beam had more powerful capacity in the aspect of destroying RAT-1cell than the X-ray irradiation, even under hypoxia, which demonstrating the highly biological effectiveness of C12for the radiation treatment. Thus, with compared to the traditional photon irradiation, the C12can inhibit or kill the cancer cells more efficaciously and carbon ion beam irradiation can act as an excellent tool in the clinical practice. Part2. Co-culture study of RAT-1and IEC-6irradiated with X-ray&Carbon ion beam (C12)Objective:To investigate the outcome in the co-culture experiment of RAT-1&IEC-6irradiated with photon (X-ray) and carbon ion (C12) under oxia or hypoxiaMaterials&methods:Under hypoxia conditions, RAT-1or IEC-6cells were cultured together after certain doses of irradiation, X-ray or Carbon ion beam, under hypoxia (0.5%Oxygen) from two instruments-hypoxia incubator&hypoxia chamber (GSI patent). Then the clonogenic formation assays were performed in the two kinds of cells and the survival fractions from co-culture or normal mono-culture were calculated one by one afterwards.Results:The PE (plating effieicncy) of the IEC-6increased in the co-culture fashion that the ratioS of PEco to PEmono were1.0914and1.0881under oxia or hypoxia respectively, while the PE of RAT-1had not the same potential compared with the normal, mono-culture after X-ray irradiation. Moreover, the survival ratios of IEC-6co-cultured with irradiated RAT-1cells were1,1.0482and1.0405under oxic condition and the potential also occurred when they stayed in the hypoxic circumstance, which meant IEC-6had the up-inclination that the ratios of the survivals in co-culture to survivals in mono-culture were more than1. However, for the RAT-1cells the similar phenomenon did not occur in the co-culture experiment which meant the co-culture had not so much influence as that in IEC-6cells. Meanwhile, with the irradiation of Carbon ion beam there was not the same effect in both cell lines and all the ratios of co-culture to mono-culture were at about1.Conclusions:The ratios of co-culture to mono-culture of IEC-6cells irradiated with X-ray were more than1while these ratios did not increase in the carbon ion irradiation. And for the RAT-1the ratios were always around at1either in photon experiment or in the carbon ion irradiation. Taking together, the co-culture has more influence on IEC-6than RAT-1in photon study; nevertheless, irradiated with carbon ion beam, the co-culture do not possesses influences in both cell lines. |
PDF Full Text Request