ViscumTT induces apoptosis and alters IAP expression in osteosarcoma in vitro and has synergistic action when combined with different chemotherapeutic drugs

Abstract

BackgroundOsteosarcoma is the most common bone tumor and is associated with a poor prognosis. Conventional therapies, surgery and chemotherapy, are still the standard but soon reach their limits. New therapeutic approaches are therefore needed. Conventional aqueous mistletoe extracts from the European mistletoe (Viscum album L.) are used in complementary cancer treatment. These commercial extracts are water-based and do not include water-insoluble compounds such as triterpenic acids. However, both hydrophilic and hydrophobic triterpenic acids possess anti-cancer properties. In this study, a whole mistletoe extract viscumTT re-created by combining an aqueous extract (viscum) and a triterpene extract (TT) was tested for its anti-cancer potential in osteosarcoma.MethodsTwo osteosarcoma cell lines were treated with three different mistletoe extracts viscum, TT and viscumTT to compare their apoptotic potential. For this purpose, annexin/PI staining and caspase-3, −8 and −9 activity were investigated by flow cytometry. To determine the mechanism of action, alterations in expression of inhibitors of apoptosis (IAPs) were detected by western blot. Apoptosis induction by co-treatment of viscum, TT and viscumTT with doxorubicin, etoposide and ifosfamide was examined by flow cytometry.ResultsIn vitro as well as ex vivo, the whole mistletoe extract viscumTT led to strong inhibition of proliferation and synergistic apoptosis induction in osteosarcoma cells. In the investigations of mechanism of action, inhibitors of apoptosis such as XIAP, BIRC5 and CLSPN showed a clear down-regulation after viscumTT treatment. In addition, co-treatment with doxorubicin, etoposide and ifosfamide further enhanced apoptosis induction, also synergistically.ConclusionViscumTT treatment results in synergistic apoptosis induction in osteosarcoma cells in vitro and ex vivo. Additionally, conventional standard chemotherapeutic drugs such as doxorubicin, etoposide and ifosfamide were able to dramatically enhance apoptosis induction. These results promise a high potential of viscumTT as an additional adjuvant therapy approach for osteosarcoma.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1545-7) contains supplementary material, which is available to authorized users.

Deciphering the Biological Activities of Dunaliella sp. Aqueous Extract from Stressed Conditions on Breast Cancer: from in Vitro to in Vivo Investigations

“…TUNEL assay labelling the 3 OH ends of apoptotic nucleus showed an intense brown staining of nucleus of 4T1 cells treated with DSS extract, which means that the extract triggers cell death by apoptosis. This result was confirmed by caspase-3 activation and PARP-1cleavage [49]. Caspase-3 activation and PARP-1 deactivation were found in cells treated with DSS extract in 12 h treatment with DSS but not with DSC.…”

Preclinical Evaluation of Antitumoral and Cytotoxic Properties of Viscum album Fraxini Extract on Pediatric Tumor Cells

“…Therefore, the impact of caspase-8 has to be investigated in other neuroblastoma cell lines in further studies. However, activation of both intrinsic and extrinsic apoptosis pathways due to mistletoe treatment was reported by other authors [32,33]. The fact that mistletoe extracts can act via activation of both caspase-8 and caspase-9 makes them suitable for the treatment of neuroblastoma, as caspase-8 inactivation (e.g., by DNA hypermethylation) is a frequent virtue of apoptosis resistance in neuroblastoma [30,34].…”

Synergistic Antitumour Properties ofviscumTTin Alveolar Rhabdomyosarcoma

“…This result is in line with the assumption that whole plant extracts can be more effective than their single constituents [ 52 – 54 ]. Synergistic effects of viscumTT were already recently shown in other paediatric tumour cell lines [ 41 – 44 ].…”

“…Previous studies showed the efficacy of a combined mistletoe extract produced by addition of solubilised triterpene acids ( TT ) to aqueous mistletoe extracts ( viscum ), creating a whole plant extract ( viscumTT ). This whole plant extract effectively induced apoptosis in acute myeloid and lymphoblastic leukaemia [ 41 , 42 ], Ewing-sarcoma [ 43 ], and osteosarcoma [ 44 ] and inhibited tumour growth in murine melanoma in vivo [ 45 ]. The aim of this study was to analyse the effect of the whole mistletoe extract, viscumTT , on rhabdomyosarcoma in vitro, ex vivo, and in vivo.…”