Timosaponin Aiii Disrupts Morphological Plasticity and Migration of Breast Adenocarcinoma Through Inhibition of Integrin Internalisation

Cell migration is a critical step in tumour invasion and metastasis. To acquire invasive properties, cancer cells use their surrounding environment through dynamic and bidirectional interactions and change their morphology and mode of migration. Thus, inhibition of morphological plasticity regulated by paracrine interactions may be a promising approach for anti-cancer therapy. In this study, we found that timosaponin AIII (TAIII), a steroidal saponin isolated from the roots of Anemarrhena asphodeloides, disrupted the morphological changes and migratory activity of breast adenocarcinoma cells promoted by paracrine interactions with mammary epithelium-derived cells. TAIII suppressed lamellipodia formation of MDA-MB-231 cells in response to exogenous stimuli from MCF10A cells, thereby inhibiting morphological changes and migration. TAIII also attenuated membrane spreading and induced contraction of HeLa cells, followed by expansion of intercellular gaps. Furthermore, we analysed the intracellular dynamics of TAIII labelled with a fluorescent dye and found that labelled TAIII was internalised in a manner dependent on dynamin. We also found that TAIII blocked internalisation of cell surface proteins including integrin b1. These results provide a novel aspect to understand how TAIII exerts pharmacological activities in suppression of cancer cell migration.

Potential Antimetastatic Effect of Timosaponin AIII against Human Osteosarcoma Cells through Regulating the Integrin/FAK/Cofilin Axis

Timosaponin AIII (TSAIII) is a steroidal saponin which demonstrates anti-tumour activities. However, the effect of TSAIII on human osteosarcoma cells remains largely unknown. In this study, we demonstrated that TSAIII exerted a significant inhibitory effect on the distribution of cytoskeletal F-actin and cytoskeletal-related proteins, which contributed to the suppression of cell migration and invasion, without inhibiting cell growth or apoptosis. In the synergistic inhibitory analysis, cotreatment of TSAIII with αVβ3 integrin inhibitor [Cyclo(RGDyK)] or focal adhesion kinase (FAK) inhibitor (PF-573228) exerted greater synergistic inhibitory effects on the expression of Intergin αVβ3/FAK/cofilin axis, thus inhibiting the migration and invasion capacities of human osteosarcoma cells. TSAIII was demonstrated to significantly inhibit the pulmonary metastasis formation of human osteosarcoma cells in vivo in metastasis animal models. These findings reveal the inhibitory effects of TSAIII on the metastasis progression of human osteosarcoma cells and the regulation of integrin-αVβ3-FAK-Src and TESK1/p-cofilin mediated cytoskeletal F-actin pathway. Therefore, TSAIII might represent a novel strategy for the auxiliary treatment of human osteosarcoma cells.

Timosaponin AIII Induces G2/M Arrest and Apoptosis in Breast Cancer by Activating the ATM/Chk2 and p38 MAPK Signaling Pathways

Timosaponin AIII (TAIII), a steroidal saponin, exerts potent anti-tumor activity in various cancers, especially breast cancer. However, the concrete molecular mechanisms of TAIII against breast cancer are still unclear. Here, we find that TAIII triggers DNA damage, leads to G2/M arrest, and ultimately induces apoptosis in breast cancer both in vitro and in vivo. TAIII induced G2/M phase arrest and apoptosis in MDA-MB-231 and MCF7 cells accompanied with down-regulation of CyclinB1, Cdc2 and Cdc25C. Further data showed that the ATM/Chk2 and p38 pathways were activated representing by up-regulated levels of p-H2A.X and p-p38, which indicated an induction of DNA damage by TAIII, leading to cell cycle arrest and apoptosis. The effects of TAIII were further confirmed by employing inhibitors of ATM and p38 pathways. In vivo, TAIII suppressed the growth of subcutaneous xenograft tumor without obvious toxicity, which indicated by Ki67 and TUNEL analysis. Data also showed that TAIII stimulated the ATM/Chk2 and p38 MAPK pathways in vivo, which in consistent with the effects in vitro. Hence, our data demonstrate that TAIII triggers DNA damage and activates ATM/Chk2 and p38 MAPK pathways, and then induces G2/M phase arrest and apoptosis in breast cancer, which provide theoretical evidence for TAIII utilized as drug against breast cancer.

Ginsenoside Rg1 Drives Stimulations of Timosaponin AIII-Induced Anticancer Effects in Human Osteosarcoma Cells

A ginsenoside Rg1 is an active compound extracted from the stem and/or root of ginseng. Rg1 has been known to affect various human organ systems including the immune, cardiovascular, and nervous systems with its pharmacological effects. Timosaponin AIII (TA3) is a type of spirostanol saponins that are the major compounds of Anemarrhena asphodeloides. TA3 exerts anticancer effects in various human cancers, and the effects include attenuations of cancer cell migration and induction of apoptosis. In this study, I report that Rg1 drives the stimulation of TA3-induced cytotoxic effects in MG63 human osteosarcoma cells. Rg1 stimulates TA3-induced apoptosis in MG63 cells via selective intensification of caspase-3 activation. Rg1 and TA3 synergistically induced antimetastatic effects such as attenuation of MG63 cell migration and inhibitions of matrix metalloproteinases (MMP-2 and MMP-9). Rg1 and TA3 synergistically suppressed JNK, p38, ERK, β-catenin, and CREB signaling, which are key regulators of cancer metastasis. Finally, the synergistic anticancer effects of Rg1 and TA3 were also observed in U2OS human osteosarcoma cells, and this may indicate that the synergy is not limited specifically to MG63 cells. The results presented here suggest that the combinatorial use of Rg1 and TA3 may be a promising way to develop an effective antiosteosarcoma agent.