The effect of sesquiterpene lactone in childhood cancer

Childhood cancer, although there is a progress in treatment and survival rates, is a cancer group in which new strategies for treatment are required. Sesquiterpene lactones (SLs) are a group of natural products found in more than 100 flowering plant families. SLs are active components of many conventional medicinal plants. The anti-cancer effect of SLs had been proved, yet there has not been any related research conducted in childhood cancer. The aim of this study is to investigate the effects of dehyroleucodine (DhL) and extracts of Inula viscosa, which contains high levels of active SLs, on childhood cancers comparatively with cisplatin (CDDP) used in classical chemotherapy. In in vitro study; Neuroblastoma cell line KELLY, Ewing sarcoma cell line SK-ES and Hepatocellular Carcinoma cell line Hep-G2 cells were used. DhL and CDDP were commercially purchased. Inula viscosa was gathered from Spil Mountain in Manisa, in August 2018. Identification of the species was conducted in Ege University Botanical Garden. The extract of the plant was obtained by solid-liquid extraction method at Ege University Faculty of Pharmacy. The antioxidant activity was determined by DPPH method, total flavonoid amount by aluminum chloride method and total phenolic substance determination by using Folin Coicalteu method. Thin layer chromatography method was used to analyze and visualize the extracts. Cell lines were cultured and 96 well-plated extracts prepared with four different solvents, LD50 doses of DhL and CDDP were determined by MTT cell viability test. Active LD50 doses were applied to all cell lines in 6 well-plates and viability and apoptosis and necrosis percentages were determined by Annexin V + PI test in flow cytometry. Morphological changes in cells were investigated with Toluidine Blue staining. In this context, Ki67 as a proliferation index, Caspase 3, 8, 9 for identifying apoptosis mechanism and immunohistochemical studies were performed. Our results were compared with Mann Whitney U test at p <0.05 level. For Kelly, a Neuroblastoma cell line, CDDP showed the expected strong effect on proliferation and apoptosis. It was observed that DhL and plant extract with methanol solvent (MBE) led to apoptosis although it reduced the proliferation less than CDDP. It is found that CDDP, MBE, and DhL, for childhood liver cancer cell line HEP-G2, caused a similar reduction in proliferation, the three agents led to apoptosis in cells and used apoptotic intrinsic pathway further. For SK-ES, an Ewing sarcoma cell line, DhL and MBE have been shown to reduce proliferation less than CDDP, but evidently, lead to apoptosis. When compared to CDDP, a drug used in the cancer treatment, both items showed similar and statistically significant anti-cancer activity. They also demonstrated this effect via apoptosis and necroptosis. In vivo experiments related to these agents should also be planned. This plant, which is naturally found in our country, after completion of in vivo experiments and full disclosure of molecular mechanisms, is a candidate for being a pediatric anti-cancer agent functionally used in the clinic. Keywords:Childhood cancer,Sesquiterpene Lactone,Inula viscosa,