Effects of small interfering RNA targeting thymidylate synthase on survival of ACC3 cells from salivary adenoid cystic carcinoma.
BACKGROUND
Thymidylate synthase (TS) is an important target for chemotherapeutic treatment of cancer and high expression of TS has been associated with poor prognosis or refractory disease in several cancers including colorectal and head and neck cancer. Although TS is known to regulate cell cycles and transcription factors, its potency as a therapeutic target has not been fully explored in adenoid cystic carcinoma (ACC).


METHODS
An ACC cell line (ACC3) was transfected with siRNA targeting the TS gene and inhibition of cell growth and induction of apoptosis-associated molecules were evaluated in vitro. In addition, the in vivo effect of TS siRNA on tumor progression was assessed using a xenograft model.


RESULTS
Our results demonstrated that ACC3 cells showed significantly higher TS expression than non-cancer cell lines and the induction of TS siRNA led to inhibition of cell proliferation. The effect was associated with an increase in p53, p21, and active caspase-3 and S-phase accumulation. We also found up-regulation of spermidine/spermine N1-acetyltransferase (SSAT), a polyamine metabolic enzyme. Furthermore, treatment with TS siRNA delivered by atelocollagen showed a significant cytostatic effect through the induction of apoptosis in a xenograft model.


CONCLUSIONS
TS may be an important therapeutic target and siRNA targeting TS may be of potential therapeutic value in ACC.
Shirasaki
Takashi
T
Department of Otolaryngology, Hirosaki University School of Medicine, Hirosaki, Japan. taka-shira@nifty.com
Maruya
Shin-ichiro
S
Mizukami
Hiroki
H
Kakehata
Seiji
S
Kurotaki
Hidekachi
H
Yagihashi
Soroku
S
Shinkawa
Hideichi
H
D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D003528:Carcinoma, Adenoid Cystic / Q000201:enzymology / Q000235:genetics / Q000473:pathology* / Q000628:therapy; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013940:Thymidylate Synthase / Q000235:genetics*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D013940:Thymidylate Synthase; D000123:Acetyltransferases; C505407:CASP3 protein, human; D053148:Caspase 3