Effects of small interfering RNA targeting thymidylate synthase on survival of ACC3 cells from salivary adenoid cystic carcinoma

Takashi Shirasaki,Hideichi Shinkawa,Seiji Kakehata,Hidekachi Kurotaki,Shin-Ichiro Maruya,Hiroki Mizukami,Soroku Yagihashi

doi:10.1186/1471-2407-8-348

Takashi Shirasaki, Hideichi Shinkawa + Show 5 more

Open Access

https://doi.org/10.1186/1471-2407-8-348

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Abstract

BackgroundThymidylate 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).MethodsAn 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.ResultsOur 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.ConclusionTS may be an important therapeutic target and siRNA targeting TS may be of potential therapeutic value in ACC.

Highlights

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
Overexpression of TS mRNA in ACC3 cells Initially, the expression level of TS mRNA transcript was evaluated with real-time RT-PCR using RNA samples from control non-cancer cell lines derived from skin keratinocytes and bronchial epithelial cells
Effect on cell survival of transfection with small interfering RNA (siRNA) targeting TS we examined the effect of TS siRNA transfection on the viability of ACC3 cells

Summary

Introduction

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. 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). ACC shows various histological patterns including tubular, cribriform, and solid types. Several molecules, including p16, p27, and E-cadherin, have been proposed as prognostic markers [2,3,4], but markers useful as therapeutic targets have not been identified in ACC. TS is a critical cellular target for 5-fluorouracil (5FU), which is widely used in the treatment of several cancers including colorectal, breast, and head and neck cancer. The inhibition of TS activity has been shown to lead to apoptotic cell death resulting from intracellular thymidine depletion [5]

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Conclusion