Sensitization of ovarian carcinoma cells to the atypical retinoid ST1926 by the histone deacetylase inhibitor, RC307: enhanced DNA damage response

• Published in: International journal of cancer Vol. 126; no. 5; pp. 1246 - 1255
• Main Authors: Zuco, Valentina, Benedetti, Valentina, De Cesare, Michelandrea, Zunino, Franco
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.03.2010; Wiley-Blackwell
• Subjects: Adamantane - administration & dosage; Adamantane - analogs & derivatives; Animals; Antineoplastic Combined Chemotherapy Protocols - pharmacology; apoptosis; Apoptosis - drug effects; atypical retinoid; Biological and medical sciences; Blotting, Western; Cell Line, Tumor; Cell Proliferation - drug effects; Cinnamates - administration & dosage; DNA damage; DNA Damage - drug effects; Enzyme Inhibitors - administration & dosage; Female; Female genital diseases; Gynecology. Andrology. Obstetrics; histone deacetylase inhibitors; Histone Deacetylases - drug effects; Humans; In Situ Nick-End Labeling; Medical sciences; Mice; Mice, Nude; Ovarian Neoplasms - drug therapy; Retinoids - administration & dosage; Tumors; Xenograft Model Antitumor Assays; Ovary carcinoma; DNA damage response; Ovary cancer; DNA damage; Retinoid; atypical retinoid; Malignant tumor; Female genital diseases; Ovarian diseases; Histone deacetylase inhibitor; Cancerology; Cell death; Atypical; Sensitization; Lesion; Cancer; Apoptosis; histone deacetylase inhibitors
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.24819

The synthetic atypical retinoids containing an adamantyl group exhibit antiproliferative or proapoptotic activities. Apoptosis induction is a dose‐dependent effect independent of retinoid receptors. We have reported that induction of apoptosis by the atypical retinoid, ST1926, is associated with early manifestations of genotoxic stress. Indeed, in this study performed in ovarian carcinoma cells, we show that exposure to ST1926 resulted in an increase of early markers of DNA damage, including ATM and H2AX phosphorylation. In addition, we found that a novel histone deacetylase (HDAC) inhibitor (RC307) was able to enhance sensitivity of ovarian carcinoma cells to ST1926. Under conditions where single‐agent treatment caused only antiproliferative effects, the combination of the atypical retinoid and HDAC inhibitor resulted in marked apoptotic cell death with a more rapid onset in wild‐type p53 ovarian carcinoma cells. The sensitization to ST1926‐induced apoptosis was associated with an enhanced DNA damage response, because a prolonged expression of DNA damage markers (e.g., H2AX, p53 and RPA‐2 phosphorylation) and a marked activation of DNA damage checkpoint kinases (in particular, phosphorylation of Chk1) were observed indicating an accumulation of DNA damage by the ST1926/HDAC inhibitor combination. The study provides additional support to the role of DNA damage as a primary event leading to the activation of apoptosis in ovarian carcinoma cells by adamantyl retinoids and documents the potential therapeutic efficacy of the combination of ST1926 and HDAC inhibitors of the novel series.