Expressions Of XIAP In Renal Cell Carcinoma (RCC) And Its Role In Drug Resistance Of RCC

Renal cell carcinoma (RCC) is one of the most common seenmalignant tumors which is secondary to bladder cancer in the urinarysystem carcinoma. Study showed that the morbidity and mortality ofRCC are increasing gradually. Except the reliable treatment of surgicalresection, RCC is insensitive to radiotherapy, chemiotherapy and internalincretion therapy, and therapeutic effect is bad.Immunotherapy hastherapeutic effect only to 15～20% patients.About 50% members of thosepatients are in their late stage when they were firstly diagnosed of thiscancer and have lost their best opportunity for treatment, about 40% willbe recurrenced and metabasised after radical renal resection, the survivalrate is lower than 5% within 3 years who had not received any treatment.So to find the tumorigenesis and seek perfect therapies of RCC are thegoals of researcher.Although pathogenesis of RCC is not very clear, but a great deal ofstudy has shown that inhibition of tumor cell apoptosis is an importantmechanism. Chemiotherapy is one of the important comprehensivetherapeutic methods of malignant tumors, but RCC is a typical sampleof drug resistance and resists many chemotherapeutic drugs. So to finddrug resistance mechanism of RCC become the urgent thing. Study alsoindicated that except the abnormal expression of P-glycoprotein (P-gp)and Glutathione (GSH), the tolerance of tumor cells to apoptosis is animportant cause of RCC be insensitive even irresponsive tochemotherapeutic drugs.x-chromosome-linked inhibitor of apoptosis(XIAP) is a newmember of inhibitors of apoptosis protein (IAP)family.It has strong effectof inhibiting apoptosis by exerting inhibitory effect on the activities ofcaspase, and so on. XIAP play an important role in the occurrence andprogress in many kind of tumors such as ovarian cancer, myeloidleukemias, prostate cancer, it is also close related with drug resistance ofthese tumors.Antisense oligonucleotide(ASODN) can well act as a geneblocker to inhibition of expression of specific gene, so this made a newway to reverse cancer drug resistance to chemotherapeutic drugs. At present, the assocition of XIAP expression characteristics with RCCdevelopment was rarely studied, and there is no report on the relationbetween XIAP and drug-sensitive of RCC cells yet. So as to studyexpression characteristics and the effect to drug-sensitive of XIAP inRCC, to study the reverse drug resistance of XIAP ASODN are veryimportant. It is significant to illustrate the mechanism of devepment anddrug resistance, and explore the methods of enhancing therapeuticsensitivity of RCC.PART ONEEpression of XIAP and caspase-3 in RCC tissuesObjective: To investigate the expression of XIAP and caspase-3 inRCC tissues, and to explore their correlations with RCC.Methods: XIAP and caspase-3 expression were detected byimmunohisto-chemistry in 50 cases RCC tissues and 15 cases of normalrenal tissuses.Results:(1)Imunohistochemical analysis showed that positiveexpression of XIAP protein was higher in RCC tissues than in normalrenal tissuses, but positive expression of caspase-3 protein is lower.Positive expression of XIAP and caspase-3 there is significant differencebetween RCC and normal renal tissuses (p＜0.01).(2)The positiveexpression of XIAP and caspase-3 showed no significant differencebetween age and gender and pathological type, but a significantdifference between pathological grades (p＜0.05); XIAP expression therewas significant difference between clinical stage(p＜0.05) and with orwithout lymph node metastasis(p＜0.01), but caspase-3 expression therewas no significant difference (p＞0.05).Conclusions:(1)XIAP protein expression up-regulated but caspase-3protein expression down-regulated in RCC tissues.(2) Positive expressionof XIAP in RCC tissues there were correlation with pathological grades,clinical stage and with or without lymph node metastasis, but positive expression of caspase-3 there was correlation with pathological gradesonly.(3)There were a negative correlation between positive expression ofXIAP and caspase-3, their change may play a important role in RCCdevelopment.PART TWOEffect of XIAP on chemotherapeutic sensitivityof RCC cell line786-0Objective: To investigate the effect of XIAP on drug resistance ofRCC and XIAP ASODN on enhancing the sensitivity of RCC tochemotherapy.To explore the drug resistance mechanism and newmethods of reversing drug resistance for RCC.Methods: Through RT-PCR, Western blot, FCM to detect the effectof different concentration chemotherapeutic drug DDP on XIAP mRNA,protein and cell apoptosis rate of RCC cell line 786-0.Then RCC cell line786-0 was transfected with different concentration of XIAP ASODN andtreated with DDP,RT-PCR, Western blot, FCM,electron microscope,MTT and so on were utilized to assay the expression of XIAP mRNA,XIAP protein and the change of cell apoptosis rate,cell proliferationactivity and caspase-3 activity in 786-0 cells.Results:(1)10umol/L or lower than 10umol/L DDP could not buthigher than 10umol/L DDP could down-regulated the expression of XIAPmRNA and protein, different concentration DDP could not induce theapoptosis of 786-0 cells significantly (p＞0.05).(2) RCC cell line 786-0was transfected by XIAP ASODN and then treated with 10umol/L DDP,the expression of XIAP mRNA and protein down-regulated significantly;the cell growth inhibition,the caspase-3 activity and cell apoptosis rateincreased significantly; the half-maximum inhibitory concentration ofDDP was decreased significantly.There were significant differences withcells treated with DDP or XIAP ASODN alonely (p＜0.05 or 0.01).Conclusions:(1)XIAP contributes to the occurrence of drug resistance of RCC, XIAP gene can be an appropriate and effective target to reversedrug resistance.(2) XIAP ASODN can down-regulated the expression ofXIAP mRNA and protein of RCC and enhance DDP sensitivity to RCC,it can by itself and promoting DDP to induce apoptosis significantly andreverse drug resistance of RCC.