| As an effective adjuvant therapy for surgery treatment of rectal cancer, radiotherapy and chemotherapy may be relevant to induced apoptosis of cancer cells and regulation and control of involved genes expression. In order to investigate the difference of apoptosis level induced by a variety of treatments in rectal cancer cells and mechanism of regulation and control of relevant genes, the thesis performs a study in two aspects-radiotherapy and chemotherapy.The first part: radiotherapy testSubject:To investigate apoptosis induced by x-ray and fast-neutron-ray and relevant gene expression in human rectal carcinoma cell line. Methods: Cells were radiated by various dose of x-ray (OGy, 2Gy, 4Gy, 6Gy, 8Gy, lOGy) and by that of fast-neutron-ray (OGy, 0.67Gy, l.34Gy, 2.OlGy, 2.68Gy, 3.34Gy), which are the same effects of radiobiology as one-third of the equivalent dose of x-ray. After that, cells were incubated for 6h, 24h, 48h, and 72h in the constant temperature of 370C. Fluorescent staining of DNA was used to detect the relation between AL (apoptotic index, percentage of apoptotic cells) and irradiation dose of x-ray and fast-neutron-ray, as well as time after radiation. The special morphological feature of apoptotic cell was observed with electron microscope. In addition, we detect gene expression for cells radiated by various dose of x-ray (0,2,4,6,8,1 OGy) and fast-neutron-ray (0,O.67,l.34,2.Ol,2.68,3.34Gy) Results: AL of cells radiated by various dose of xray and fast-neutron-ray gradually increased with the increase of dose and time in human rectal cancer cell line. Furthermore, at the same point of time, AL of cells induced by fast- neutron-ray was higher than that induced by x-ray. For cells radiated by various dose of x-ray, down-regulated expression of p53 rotein was observed significantly, but bcl-2 protein wasn抰. For cells radiated by various dose of fa~t-~neutron-ray, it wasn抰 observed that the significant down-regulated expression of p53 protein and protein. Conclusion: Our results indicate, the apoptotic response induced by x-ray and fast-neutron-ray in rectal carcinoma cell line is time-dose dependent. The more time and dose increased, the more AL increased, without observing the appearance of plateau. The apoptotic response induced by fast-neutronray was higher than by x-ray in human rectal cancer cell line. Additionally, downregulated expression of p53 protein and bcl-2 protein has shown that p53 tumor suppressor gene and bcl-2 protooncogene are both involved in the control of apoptotic gene expression.SThe second part: chemotherapy +radiotherapy testSubject: To investigate aPoptosis induced by the combination of radiotherapy andchemotheraPy (5-Fu-CDDP) and relevant gene expression in human rectal cancer cellline. Methods Cells were divided in two groups. One group was treated bychemotheraPy, and the other was treated by chemotherapy and radiotherapy. Byspecial fluorescent staining of DNA, we detected aPoptotic cells and numbered AI(Percentage of aPoptotic cells) for cells treated by the two different means, so that wehave a comparison of apoptotic level fOr cells treated by the two different means.Apoptosis of cells were evaluated by DNA agrose electrophoresis and TUNEL(terminal-deoxynucleotidyl transferase mediated d-UTP nick and labeling).Additionally, Cells were treated by x-ray, 5-Fu, CDDP, 5-Fu-CDDP, x-ray-5-Fu-CDDP respectively. The expression of p53 protein and bcl-2 protein were detected byimmunohistochemical method fOr the cells treated by five different factors mentionedabove. Results The more time and dose increased in C group by the single use of 5-Fu or CDDP, the more AI increased; The significam increase of AI has aPpeared bythe combination use of 5-Fu-CDDP compared with the single use of 5-Fu or CDDP;So has the significan increase of AI by the combination of radiotherapy andchemotheraPy compared with by the single use of chemotherapy. Especially the groupof the combination of radiotherapy with 5-Fu-CDDP has the h...
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