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言語
英語
著者
関原 和正
原嶋 奈々江
頓宮 美樹
内田 伸恵
内容記述(抄録等)
Hyperthermia (HT) improves the efficacy of anti-cancer radiotherapy and chemotherapy. However, HT also inevitably evokes stress responses and increases the expression of heat-shock proteins (HSPs) in cancer cells. Among the HSPs, HSP70 is known as a pro-survival protein. In this study, we investigated the sensitizing effect of pifithrin (PFT)-μ, a small molecule inhibitor of HSP70, when three human prostate cancer cell lines (LNCaP, PC-3, and DU-145) were treated with HT (43°C for 2 h). All cell lines constitutively expressed HSP70, and HT further increased its expression in LNCaP and DU-145. Knockdown of HSP70 with RNA interference decreased the viability and colony-forming ability of cancer cells. PFT-μ decreased the viabilities of all cell lines at one-tenth the dose of Quercetin, a well-known HSP inhibitor. The combination therapy with suboptimal doses of PFT-μ and HT decreased the viability of cancer cells most effectively when PFT-μ was added immediately before HT, and this combination effect was abolished by pre-knockdown of HSP70, suggesting that the effect was mediated via HSP70 inhibition. The combination therapy induced cell death, partially caspase-dependent, and decreased proliferating cancer cells, with decreased expression of c-Myc and cyclin D1 and increased expression of p21^<WAF1/Cip>, indicating arrest of cell growth. Additionally, the combination therapy significantly decreased the colony-forming ability of cancer cells compared to therapy with either alone. Furthermore, in a xenograft mouse model, the combination therapy significantly inhibited PC-3 tumor growth. These findings suggest that PFT-μ can effectively enhance HT-induced antitumor effects via HSP70 inhibition by inducing cell death and arrest of cell growth, and that PFT-μ is a promising agent for use in combination with HT to treat prostate cancer.
掲載誌名
PLoS One
8
11
開始ページ
e78772
ISSN
19326203
発行日
2013-11-14
DOI
PubMed ID
出版者
Public Library of Science
資料タイプ
学術雑誌論文
権利関係
© 2013 Sekihara et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
業績ID
e21509
部局
医学部
研究・学術情報機構 総合科学研究支援センター
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