ABSTRACT
Objective To study the expression of signal transducer and activator of transcription 1 (STAT1) in human renal clear cell carcinoma (RCC) and the effect of STATI inhibition on the radiosensi-tivity of RCC. Methods The expression of STAT1 in 34 human RCC samples compared with 12 normal kid-ney tissues was examined by immunohistochemistry method. For in vitro experiments, a human RCC cell line, CRL-1932, was used. Western blotting was performed to evaluate the expression of total and phospory-lated STAT1. Fludarabine and siRNA were respectively used to inhibit the expression of STAT1 in CRL-1932 cells. Clonogenic assay and trypan blue staining assay were used to evaluate the radiosensitivity of CRL-1932 cells. Results The expression of both total and phospborylated STAT1 in human RCC samples was signifi-cantly higher when compared to normal kidney tissues. Similarly, the expression of STAT1 was higher in CRL-1932 cells when compared to fibroblast and Wilm's tumor cell lines. STAT1 expression was inhibited by both fludarabine and siRNA. Radiosensitivity of CRL-1932 cells was enhanced by both fludarabine and siRNA induced STAT1 inhibition. Conclusions STAT1 is over-expressed in both human RCC tissue and cell line. Inhibition of STAT1 can enhance the radiosensitivity of RCC cells.
ABSTRACT
Objective To impmve the method of "modified comet assay" in predicting the radiosensitivitv of solid tumor. Methods A single cell suspension from biopsy sample was lmdlated on ice with a dose of 5 Gy.The microscope slide was spread with agarose,lysed for 50 minutes,rinsed 3 times rinse solution,and given electrophoresis for 20 minutes. After being stained with PI,cell images were collected through the microscope and analyzed with Lucia G software(Version 4.6).In order to check system/ background errors,every sample was made into control slide and irradiation slide.The end-points were cell DNA contents and tail moment. Results The factors influencing the results included:(1)Sample was iaulty tor the biopsv taken from mucosa and no tumor cells were contained. (2)The slides with a high backgmund ( induced by necrosis) disturbed the measurement of comet assay. (3) Setting lymphocytes as control to check svstem errors was very important. (4)To separately collect images of the normal tissue cells and tumor cells from the biopsy sample improved the conformity between the clinical obscrvation and the lab result. Conclusions To increase the correlation between comet assay and clinical response,it is very helpful to set double control for checking system/background errors and to collect images of the normal tissue cells and tumor cells through the microscope,respectively.