eriocalyxin-b and Breast-Neoplasms

Eriocalyxin B (EriB), a natural ent-kaurane diterpenoid presented in the plant Isodon eriocalyx var. laxiflora, has been reported to diminish angiogenesis-dependent breast tumor growth. In the present study, the effects of EriB on human breast cancer and its underlying mechanisms were further investigated. The in vitro anti-breast cancer activity of EriB was determined using MCF-7 and MDA-MB-231 cell lines. MDA-MB-231 xenograft model of human breast cancer was also established to explore the anti-tumor effect in vivo. We found that EriB was able to induce apoptosis accompanied by the activation of autophagy, which was evidenced by the increased accumulation of autophagosomes, acidic vesicular organelles formation, the microtubule-associated protein 1A/1B-light chain 3B-II (LC3B-II) conversion from LC3B-I and p62 degradation. Meanwhile, EriB treatment time-dependently decreased the phosphorylation of Akt, mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70S6K), leading to the inhibition of Akt/mTOR/p70S6K signaling pathway. Moreover, the blockage of autophagy obviously sensitized EriB-induced cell death, which suggested the cytoprotective function of autophagy in both MCF-7 and MDA-MB-231 cells. Interestingly, the autophagic features and apoptosis induction were prevented by reactive oxygen species (ROS) scavenger N-acetyl-l-cysteine, indicating that ROS played an essential role in the mediation of EriB-induced cell death. Furthermore, in MDA-MB-231 xenograft model, EriB displayed a significant anti-tumor effect via the activation of autophagy and apoptosis in breast tumor cells. Taken together, our findings firstly demonstrated that EriB suppressed breast cancer cells growth both in vitro and in vivo, and thus could be developed as a promising anti-breast tumor agent.

Topics: Animals; Antineoplastic Agents, Phytogenic; Autophagy; Breast Neoplasms; Diterpenes; Female; Humans; Mammary Neoplasms, Experimental; MCF-7 Cells; Proto-Oncogene Proteins c-akt; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

Eriocalyxin B (EriB), a natural ent-kaurane diterpenoid isolated from the plant Isodon eriocalyx var. laxiflora, has emerged as a promising anticancer agent. The effects of EriB on angiogenesis were explored in the present study. Here we demonstrated that the subintestinal vein formation was significantly inhibited by EriB treatment (10, 15 μM) in zebrafish embryos, which was resulted from the alteration of various angiogenic genes as shown in transcriptome profiling. In human umbilical vein endothelial cells, EriB treatment (50, 100 nM) could significantly block vascular endothelial growth factors (VEGF)-induced cell proliferation, tube formation, cell migration and cell invasion. Furthermore, EriB also caused G1 phase cell cycle arrest which was correlated with the down-regulation of the cyclin D1 and CDK4 leading to the inhibition of phosphorylated retinoblastoma protein expression. Investigation of the signal transduction revealed that EriB inhibited VEGF-induced phosphorylation of VEGF receptor-2 via the interaction with the ATP-binding sites according to the molecular docking simulations. The suppression of VEGFR-2 downstream signal transduction cascades was also observed. EriB was showed to inhibit new blood vessel formation in Matrigel plug model and mouse 4T1 breast tumor model. EriB (5 mg/kg/day) treatment was able to decrease tumor vascularization and suppress tumor growth and angiogenesis. Taken together, our findings suggested that EriB is a novel inhibitor of angiogenesis through modulating VEGFR-2 signaling pathway, which could be developed as a promising anti-angiogenic agent for treatment of angiogenesis-related human diseases, such as cancer.

Topics: Angiogenesis Inhibitors; Animals; Animals, Genetically Modified; Binding Sites; Breast Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Diterpenes; Dose-Response Relationship, Drug; Female; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Developmental; Human Umbilical Vein Endothelial Cells; Humans; Mice, Inbred BALB C; Molecular Docking Simulation; Neovascularization, Pathologic; Neovascularization, Physiologic; Phosphorylation; Protein Binding; Signal Transduction; Time Factors; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; Zebrafish; Zebrafish Proteins

Three new, seco-ent-kaurane diterpenoids, laxiflorins A, B and C, together with four known diterpenoids eriocalyxin B, oriodonin, and maeocrystals A and B, were isolated from the leaves of Isodon eriocalyx var. laxiflora. Their structures were assigned by a combination of one- and two-dimensional NMR techniques and computer modeling calculations. Laxiflorin C displayed weak cytotoxic activity.

Topics: Antineoplastic Agents; Astrocytoma; Breast Neoplasms; Cell Line; Cell Survival; China; Diterpenes; Drug Screening Assays, Antitumor; Humans; KB Cells; Lung Neoplasms; Magnetic Resonance Spectroscopy; Male; Models, Molecular; Molecular Structure; Plants, Medicinal; Prostatic Neoplasms; Structure-Activity Relationship; Tumor Cells, Cultured