1.Construction Of Lentiviral Vector Of RNA Interference Of Survivin Gene 2.Dosimetric Study Of Intensity Modulated Radition Therapy In Nasopharyngeal Carcinoma

Part one: Construction of lentiviral vector of RNA interferenceof Survivin geneObjectiveSurvivin is a newly found member of IAP (inhibitor of apoptosis protein) familiy.It is expressed in almost all of the tumor cells that proliferate rapidly. It can maketumor cells proliferate and evade apoptosis and is related to drug and radiationresistance. In this study: we will construct lentivirus mediated RNAi targetingsurvivin gene in order to research function of survivin gene.MethodsWe choosed three target gene sequences of survivin gene using software oftarget finder (www.ambion.com) and designed the single-stranded DNA oligos.Double-stranded Oligoes (ds oligo) were generated. pENTR/U6-survivinA,pENTR/U6-survivinB and pENTRAJ6-survivinC entry plasmids were constructed.The entry plasmids and lentiviral vector were performed LR recombination reaction and lentiviral expression plasmids pLenti-survivinA, pLenti-survivinB andpLenti-survivinC were constructed. We used lentiviral expression plasmids andpackaging plasmids to transduct 293FT to pruduce LenfiSurvivinA, LentiSurvivinB,LentiSurvivinC and titate the lentivirus.Results1. pENTR/U6-survivinA, pENTR/U6-survivinB and pENTR/U6-survivinC entryplasmid were constructed.2. Lentiviral expression plasmids pLenti-survivinA, pLenfi-survivinB andpLenti-survivinC were successfully constructed.3. LentiSurvivinA, LentiSurvivinB and LentiSurvivinC were produced, Themolecular copies were 6.1×10¹⁰/ml,5.6×10¹⁰/ml and 1.6×10¹⁰/mlrespectively.ConclusionWe constructed three kinds of recombined lentivirus mediated RNAi targetingsurvivin gene.Part two: Dosimetric study of intensity modulated raditiontherapy in nasopharyngeal carcinomaNasopharyngeal carcinoma (NPC) is a common malignant tumor in the head andneck. Radiation therapy is the best choice of treatment for NPC. intensitymodulated radition therapy(IMRT) can result in better curative effect and less damageof normal tissue.Objective:To evaluate the dose distribution of PTVs and normal tissues in IMRT treatment plan designed for NPC patients. The dose delivered to parotid gland was comparedbetween IMRT and Routine radiotherapy.Methods:Both IMRT and RT Treatment plans were designed according to the CT images of tenNPC patients. The target volume's mean dose,target coverage (V95) andheterogeneity index(HI) were calculated. Dose distribution of the normal tissue wasanalyzed. The dose delivered to parotid gland was compared.Results:1. The mean dose ofPTVlnx, PTVlnd, PTV2 and PTV3 were respectively:66.80±0.93, 66.21±1.43, 59.65±2.84 and 54.21±3.90.2. The HI of PTVlnx, PTVlnd, PTV2å’ŒPTV3 were respectively: 1.064±0.02,1.084±0.03,1.164±0.05 and 1.28±0.08.3. The V95 of PTVlnx, PTVlnd, PTV2å’ŒPTV3 were respectively＞99%.4. The dose ofparotid gland in IMRT plan and RT were respectively. 32.67±5.71and 61.44±3.52(t=13.27, P=3.25×10^-7).Conclusion:Compared with routine radiotherapy, the IMRT plan can provide ideal dosedistribution in PTVs and normal tissue, and much lower dosage in the parotid gland.