The histone deacetylase inhibitor trichostatin A synergistically resensitizes a cisplatin resistant human bladder cancer cell line.
OBJECTIVE
Cisplatin is the mainstay of treatment for advanced bladder cancer. However, intrinsic or acquired resistance to cisplatin is common, which severely limits its therapeutic potential. We determined the synergistic antitumor effect of cisplatin and the histone deacetylase inhibitor trichostatin A in cisplatin resistant human bladder cancer cells.


METHODS
The cisplatin resistant human bladder cancer cell line T24R2 was exposed to cisplatin and/or trichostatin A. Tumor cell proliferation was examined by cell counting kit assay. Synergism between 2 drugs was examined by the combination index. Changes in cell cycle and apoptosis were determined by flow cytometry. We analyzed the expression of caspase-3, 8 and 9, poly(adenosine diphosphate-ribose) polymerase, p21WAF1/CIP1, cyclin A, B1 and D1, Cdc2c, p-Cdc2c, Cdc25c, p-Cdc25c, cytochrome c, p-Akt, t-Akt, Bcl-2, Bax, Bad, vascular endothelial growth factor and fetal liver kinase-1 by Western blot and colorimetric assay.


RESULTS
Based on the combination index and isobole analysis of the Cell Counting Kit-8 assay we observed a strong synergistic antitumor effect between cisplatin and trichostatin A, allowing a 3.5 and 4.9-fold dose reduction in cisplatin and trichostatin A, respectively, while achieving an estimated 90% kill of T24R2 cells. The underlying mechanism could be synergistic cell cycle arrest, induction of caspase mediated apoptosis or up-regulated expression of pro-apoptotic Bad and Bax.


CONCLUSIONS
Results indicate that trichostatin A may synergistically enhance the antitumor effect of cisplatin and resensitize cisplatin resistant bladder cancer cells. These findings suggest the potential use of histone deacetylase inhibitor as a combination agent to enhance the antitumor effect of cisplatin in patients with advanced bladder cancer.
Department of Urology, School of Medicine, Seoul National University, Bndang Hospital, Gyeonggi-do, Korea.
Cheol Yong
CY
Yoon
Mi Jung
MJ
Park
Jung Sun
JS
Lee
Sang Chul
SC
Lee
Jong Jin
JJ
Oh
Hongzoo
H
Park
Chang Wook
CW
Chung
Murod M
MM
Abdullajanov
Seong Jin
SJ
Jeong
Sung Kyu
SK
Hong
Seok Soo
SS
Byun
Eun Sik
ES
Lee
Sang Eun
SE
Lee
D000970:Antineoplastic Agents / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D056572:Histone Deacetylase Inhibitors / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D006801:Humans; D006877:Hydroxamic Acids / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000473:pathology
D000970:Antineoplastic Agents; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C012589:trichostatin A; D002945:Cisplatin