RESUMO
Tanshinone I (Tan I) is one of the main bioactive ingredients derived from Salvia miltiorrhiza Bunge, which has exhibited antitumor activities toward various human cancer cells. However, its effects and underlying mechanisms on human chronic myeloid leukemia (CML) cells still require further investigation. This study determined the effects and mechanisms of anti-proliferative and apoptosis induction activity induced by Tan I against K562 cells. The cytotoxic effect of Tan I at varying concentrations on K562 cells was evaluated via MTT assay. Cell apoptosis was further investigated through DAPI staining and flow cytometry analysis. The expression levels of apoptosis-related proteins and activities of JNK/ATF2 and ERK signaling pathways were analyzed by western blot. Quantitative PCR was performed to further determine mRNA expression levels of JNK1/2 and ERK1/2 after Tan I treatment. The results indicated that Tan I significantly inhibited K562 cell growth and induced apoptosis in a concentration- and time-dependent manner. It induced significant cellular morphological changes and increased apoptosis rates in CML cells. Tan I promoted the cleavages of caspase-related proteins, as well as increased the expression levels of PUMA. Furthermore, Tan I significantly activated JNK and inhibited ATF-2 and ERK signaling pathways. The mRNA expression levels of JNK1/2 and ERK1/2 were up-regulated by Tan I, further confirming its regulatory effects on JNK/ERK signaling pathways. Overall, our results indicated that Tan I suppressed cell viability via JNK- and ERK-mediated apoptotic pathways in K562 cells, suggesting that it might be a promising candidate as a novel anti-leukemia drug.
Assuntos
Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Abietanos/farmacologia , Apoptose , Linhagem Celular TumoralRESUMO
BACKGROUND: Osteogenic differentiation of bone mesenchymal stem cells (BMSCs) is regulated by numerous signaling pathways. Dopamine (DA), a neurotransmitter, has previously been demonstrated to induce new bone formation by stimulating the receptors on BMSCs, but the essential mediators of DA-induced osteogenic signaling remain unclear. METHODS: In this work, we evaluated the influence of both dopamine D1 and D2 receptor activation on BMSC osteogenic differentiation. Gene and protein expression of osteogenic-related markers were tested. The direct binding of transcriptional factor, Runx2, to those markers was also investigated. Additionally, cellular differentiation-associated signaling pathways were evaluated. RESULTS: We showed that the expression level of the D1 receptor on BMSCs increased during osteogenic differentiation. A D1 receptor agonist, similar to DA, induced the osteogenic differentiation of BMSCs, and this phenomenon was effectively inhibited by a D1 receptor antagonist or by D1 receptor knockdown. Furthermore, the suppression of protein kinase A (PKA), an important kinase downstream of the D1 receptor, successfully inhibited DA-induced BMSC osteogenic differentiation and decreased the phosphorylation of ERK1/2. Compared with P38, MAPK, and JNK, DA mainly induced the phosphorylation of ERK1/2 and led to the upregulation of Runx2 transcriptional activity, thus facilitating BMSC osteogenic differentiation. On the other hand, an ERK1/2 inhibitor could reverse these effects. CONCLUSIONS: Taken together, these results suggest that ERK signaling may play an essential role in coordinating the DA-induced osteogenic differentiation of BMSCs by D1 receptor activation.