The olive tree phenolic component oleuropein (OLE) and its derivatives have shown many biological properties, thus representing promising novel therapeutics for the treatment of several diseases, including neoplasia. In this study, we evaluated the activities of OLE and its peracetylated derivative (peracetylated oleuropein, Ac-OLE) against two thyroid tumor cell lines that host genotypic alterations detected in human papillary thyroid cancer. TPC-1 and BCPAP cells were treated with OLE and Ac-OLE, and the effects on viability were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell counting, and trypan blue exclusion assays. Antioxidant effects were analyzed by measuring the reactive oxygen species (ROS) in basal conditions and after treatment with hydrogen peroxide (H2O2). Activity of MAP kinase and PI3K–Akt signaling pathways was evaluated by examining the levels of phosphorylated ERK and Akt by western blot. We found that OLE significantly inhibited the proliferation of both cell lines. This effect was paralleled by a reduction of basal phospho-Akt and phospho-ERK levels and H2O2-induced ROS levels. A stronger effect was elicited by Ac-OLE either in inhibiting cell growth or as an antioxidant, in particular on BCPAP cells. Our results demonstrate that OLE and especially Ac-OLE inhibit in vitro thyroid cancer cell proliferation acting on growth-promoting signal pathways, as well as exerting antioxidant effects. Further studies will reveal the potential application as novel targeted therapeutics in thyroid cancer.
Stefania Bulotta, Rosanna Corradino, Marilena Celano, Jessica Maiuolo, Maria D'Agostino, Manuela Oliverio, Antonio Procopio, Sebastiano Filetti and Diego Russo
Maria D'Agostino, Marialuisa Sponziello, Cinzia Puppin, Marilena Celano, Valentina Maggisano, Federica Baldan, Marco Biffoni, Stefania Bulotta, Cosimo Durante, Sebastiano Filetti, Giuseppe Damante and Diego Russo
The TSH receptor (TSHR) and sodium/iodide symporter (NIS) are key players in radioiodine-based treatment of differentiated thyroid cancers. While NIS (SLC5AS) expression is diminished/lost in most thyroid tumors, TSHR is usually preserved. To examine the mechanisms that regulate the expression of NIS and TSHR genes in thyroid tumor cells, we analyzed their expression after inhibition of ras–BRAF–MAPK and PI3K–Akt–mTOR pathways and the epigenetic control occurring at the gene promoter level in four human thyroid cancer cell lines. Quantitative real-time PCR was used to measure NIS and TSHR mRNA in thyroid cancer cell lines (TPC-1, BCPAP, WRO, and FTC-133). Western blotting was used to assess the levels of total and phosphorylated ERK and Akt. Chromatin immunoprecipitation was performed for investigating histone post-translational modifications of the TSHR and NIS genes. ERK and Akt inhibitors elicited different responses of the cells in terms of TSHR and NIS mRNA levels. Akt inhibition increased NIS transcript levels and reduced those of TSHR in FTC-133 cells but had no significant effects in BCPAP. ERK inhibition increased the expression of both genes in BCPAP cells but had no effects in FTC-133. Histone post-translational modifications observed in the basal state of the four cell lines as well as in BCPAP treated with ERK inhibitor and FTC-133 treated with Akt inhibitor show cell- and gene-specific differences. In conclusion, our data indicate that in thyroid cancer cells the expression of TSHR and NIS genes is differently controlled by multiple mechanisms, including epigenetic events elicited by major signaling pathways involved in thyroid tumorigenesis.