Effect of temsirolimus on bladder cancer cells in vitro and in vivo

Abstract

Objective To examine the effects of temsirolimus, an inhibitor of mammalian target of rapamycin, on bladder cancer cell lines T24 and BIU-87 in vitro and in vivo for purpose of evaluating the probability of mTOR targeted therapy for bladder cancer.Methods After being treated by a different concentration of temsirolimus, T24 and BIU-87 cells were tested by MTT assay for cell proliferation activity.Cell cycle and apoptosis analysis were performed with flow cytometer. Wound scratch assay was used for cell migration activity and transwell motility assay. Western blot analysis was used to test the mTOR phosphorylation. Subcutaneous inoculation of 6-week-old nude mice was performed using 1 × 106 T24 cells in 50％ matrigel for both control (n = 10) and temsirolimus (n = 10) groups. The volume of tumors was examined and then the expression of Ki-67 was detected by immunohistochemistry.Results Temsirolimus significantly inhibited proliferation of T24 and BIU-87 cells in a dose- and time-dependent manner. After administration of temsirolimus on T24 and BIU-87 cell lines for 24 h, the rate of wound healing in 0 nmol/L groups were (88.9 ± 14. 1 ) ％ and ( 83.6 ± 16.3)％ , which were higher than in the 5 nmol/L groups, which were (42.7 ± 11.6) ％ and ( 36.9 ± 9.7 ) ％ ( P ＜ 0.05 ). In the transwell motility assay, the number of cells in the 0 nmol/L group was 26.5 ± 5.8 and 28.2 ± 4.6, which was higher than in the 5 nmol/L group ( 19.0 ±3. 8 and 21.3 ± 5.1, respectively) (P ＜ 0. 05). When temsirolimus was administered on T24 and BIU-87 cell lines for 48 h the percentages of cells delayed in phase G0/G1 in 5 nmol/L group were ( 77.46 ±6.11)％ and (73. 39 ± 4. 94)％ respectively, and higher than in the 0 nmol/L group, which were (65.99 ±5.01 )％ 、(60.15 ±3.98)％ (P ＜0.05). There was no statistically significant difference in the apoptosis rate between the two groups (P ＞ 0.05 ). In Western blot analysis, the ratios of p-mTOR/β-actin were 0.92 ±0.09 and 1.01 ± 0.08 in 0 nmol/L group, and higher than in the 5 nmol/L group (0.47 ±0.05、0.04 ±0. 01 ) (P ＜ 0.05 ). After administration of temsirolimus for 21 days, the tumor volume in nude mice in the control group were 351.1 ± 139.9 mm3 , which was larger than 351.1 ± 139.9 mm3 in the temsirolimus group ( P ＜ 0.05 ). The positive rate of Ki-67 expression was ( 67.3 ± 8.4 ) ％ in the control group, which was higher than in the temsirolimus group ( 35.5 ± 6.7 ) ％ ( P ＜ 0.05 ). Conclusions This study provides in vitro and in vivo evidence that temsirolimus may inhibit the viability of bladder cancer cells and temsirolimus could be exploited as a potential therapeutic strategy in bladder cancer. Key words: Mammalian target of rapamycin; Bladder cancer; Treatment