Withanolide D Enhances Radiosensitivity of Human Cancer Cells by Inhibiting DNA Damage Non-homologous End Joining Repair Pathway

Article Article scientifique Article Withanolide D Enhances Radiosensitivity of Human Cancer Cells by Inhibiting DNA Damage Non-homologous End Joining Repair Pathway eng 2020 author Lacombe Jerome author Cretignier Titouan 821043 author Meli Laetitia 820770 author Wijeratne E. M. Kithsiri author Veuthey Jean-Luc 22317 author Cuendet Muriel 0000-0002-1523-1907 686755 author Gunatilaka A. A. Leslie author Zenhausern Frédéric 26732 10.3389/fonc.2019.01468 31970089 2234-943X https://www.frontiersin.org/article/10.3389/fonc.2019.01468/full Along with surgery and chemotherapy, radiation therapy (RT) is an important modality in cancer treatment, and the development of radiosensitizers is a current key challenge in radiobiology tomaximize RT efficiency. In this study, the radiosensitizing effect of a natural compound from the withanolide family, withanolide D (WD), was assessed. Clonogenic assays showed that a 1 h WD pretreatment (0.7μM) before irradiation decreased the surviving fraction of several cancer cell lines. To determine the mechanisms by which WD achieved its radiosensitizing effect, we then assessed whether WD could promote radiation-induced DNA damages and inhibit double-strand breaks (DSBs) repair in SKOV3 cells. Comet and gH2AX/53BP1 foci formation assays confirmed that DSBs were higher between 1 and 24 h after 2 Gy-irradiation in WD-treated cells compared to vehicle-treated cells, suggesting that WD induced the persistence of radiation-induced DNA damages. Immunoblotting was then performed to investigate protein expression involved in DNA repair pathways. Interestingly, DNA-PKc, ATM, and their phosphorylated forms appeared to be inhibited 24 h post-irradiation in WD-treated samples. XRCC4 expression was also down-regulated while RAD51 expression did not change compared to vehicle-treated cells suggesting that only non-homologous end joining (NHEJ) pathways was inhibited by WD. Mitotic catastrophe (MC) was then investigated in SKOV3, a p53-deficient cell line, to assess the consequence of such inhibition. MC was induced after irradiation and was predominant in WD-treated samples as shown by the few numbers of cells pursuing into anaphase and the increased amount of bipolar metaphasic cells. Together, these data demonstrated that WD could be a promising radiosensitizer candidate for RT by inhibiting NHEJ pathway and promoting MC. Additional studies are required to better understand its efficiency and mechanism of action in more relevant clinical models. Withanolide D Cancer Radiation Radiosensitizer DNA damage repair Mitotic catastrophe Dewey 617 57 Département de chirurgie 222 false 881 Sciences analytiques Frontiers in Oncology 9 1468 d934e515-c1bc-4980-a871-33c8fd7c3662 Article (Published version) Public fonc-09-01468.pdf 1416947 application/pdf CC BY openAccess Faculté de médecine / Section de médecine clinique / Département de chirurgie

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Withanolide D Enhances Radiosensitivity of Human Cancer Cells by Inhibiting DNA Damage Non-homologous End Joining Repair Pathway	Frontiers in Oncology			2020	442	305

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Cretignier, Titouan