Marine derived macrolide bryostatin 4 inhibits the TGF-ß signaling pathway against acute erythroleukemia.

PURPOSE: Acute erythroleukemia (AEL) is a rare and highly aggressive subtype of acute myeloid leukemia (AML) with an extremely poor prognosis when treated with available drugs. Therefore, new investigational agents capable of inducing remission are urgently required. METHODS: Bioinformatics analysis, western blot and qRT-PCR were used to reveal the potential biological mechanism of bryostatin 4 (B4), an antineoplastic macrolide derived from the marine bryozoan Bugula neritina. Then, in vivo experiments were conducted to evaluate the role of transforming growth factor (TGF)-ß signaling in the progression of AEL. RESULTS: Our results revealed that the proliferation of K562 cells and TF-1 cells was significantly inhibited by B4 at IC50 values of 37 nM and 52 nM, respectively. B4 inhibited TGF-ß signaling and its downstream pathway targets, particularly the phosphorylation of Smad2, Smad3, Ras, C-RAF, ERK1/2, and MEK. B4 also played an important role in cell invasion and migration in K562 cells and TF-1 cells by reducing the protein levels of the mesenchymal cell marker vimentin. Moreover, Flow cytometry and western blot analyses demonstrated that B4 induced apoptosis and initiated G0/G1 phase arrest by modulating mitochondrial dysfunction and cyclin-dependent kinase (CDK) expression. CONCLUSION: These findings indicated that B4 could inhibit the proliferation, migration, invasion, and TGF-ß signaling pathways of AEL cells, thus suggesting that B4 possesses therapeutic potential as a treatment for AEL.

Marine sponge-derived alkaloid inhibits the PI3K/AKT/mTOR signaling pathway against diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is a genetically heterogeneous non-Hodgkin lymphoma that is extremely aggressive and has an intermediate to high malignancy. Some patients still experience treatment failure, relapse, or resistance to rituximab, cyclophosphamide, adriamycin, vincristine, and prednisone (R-CHOP) therapy. Therefore, there is an urgent need for further research on new agents for the treatment of DLBCL. AP-48 is an aaptamine alkaloid analog with potent anti-tumor effects that originates from marine natural products. In this study, we found that AP-48 exhibits dose-dependent cytotoxicity in DLBCL cell lines. Flow cytometry showed that AP-48 induced cell cycle arrest in the G0/G1 phase in SU-DHL-4 and Farage cells and in the S phase in WSU-DLCL-2 cells. AP-48 also accelerated apoptosis via the caspase-3-mediated intrinsic apoptotic pathway. Further experiments demonstrated that AP-48 exerted its anti-DLBCL effects through the PI3K/AKT/mTOR pathway, and that the PI3K agonist YS49 partially alleviated the inhibition of cell proliferation and apoptosis induced by AP-48. Finally, in a tumor xenograft model, AP-48 inhibited tumor growth and promoted apoptosis in tumor tissues, indicating its therapeutic potential in DLBCL.