RCE­4, a potential anti­cervical cancer drug isolated from Reineckia carnea, induces autophagy via the dual blockade of PI3K and ERK pathways in cervical cancer CaSki cells.

The steroidal saponin RCE­4 (1ß, 3ß, 5ß, 25S)­spirostan­1, 3­diol 1­[α­L­rhamnopyranosyl­(1→2)­ß­D­xylopyranoside], isolated from Reineckia carnea, exerts significant anti­cervical cancer activity by inducing apoptosis. The potential effect of RCE­4 on proliferation inhibition and autophagy induction has rarely been studied. Therefore, the focus of the present study was to investigate the effects of RCE­4 on proliferation, and to elucidate the detailed mechanisms involved in autophagy induction in cervical cancer cells. CaSki cells were treated with RCE­4 or/and autophagy inhibitors, and the effect of RCE­4 on cellular proliferation was assessed by MTT assay. The pro­autophagic properties of RCE­4 were subsequently confirmed using monomeric red fluorescent protein­green fluorescent protein­microtubule­associated proteins 1A/1B light chain 3B (LC3) adenoviruses and CYTO­ID autophagy assays, and by assessing the accumulation of lipid­modified LC3 (LC3II). The mechanisms of RCE­4­induced autophagy were investigated by western blot analysis. The results demonstrated that inhibiting autophagy significantly promoted RCE­4­induced cell death, indicating that autophagy served a protective role following RCE­4 treatment. In addition, RCE­4­induced autophagy was reflected by increased expression levels of the serine/threonine­protein kinase ULK1, phosphorylated (p)­ULK1, p­Beclin­1 and LC3II, the formation of autophagosomes and autolysosomes, and sequestosome 1 (p62) degradation. Subsequent analysis indicated that RCE­4 activated the AMP­activated protein kinase (AMPK) pathway by upregulating AMPK and p­AMPK, and also inhibited the PI3K and extracellular signal­regulated kinase (ERK) signaling pathways by downregulating p­PI3K, p­Akt, p­mTOR, Ras, c­Raf, p­c­Raf, dual specificity mitogen­activated protein kinase kinase (MEK)1/2, p­MEK1/2 and p­Erk1/2. Additionally, with increased treatment times RCE­4 may impair lysosomal cathepsin activity and inhibit autophagy flux by suppressing the expression of AMPK, p­AMPK, ULK1, p­ULK1 and p­Beclin­1, and upregulating that of p62. These results indicated that the dual RCE­4­induced inhibition of the PI3K and ERK pathways may result in a more significant anti­tumor effect and prevent chemoresistance, compared with the inhibition of either single pathway; furthermore, dual blockade of PI3K and ERK, and the AMPK pathway may be involved in the regulation of autophagy caused by RCE­4. Taken together, RCE­4 induced autophagy to protect cancer cells against apoptosis, but AMPK­mediated autophagy was inhibited in the later stages of RCE­4 treatment. In addition, autophagy inhibition improved the therapeutic effect of RCE­4. These data highlight RCE­4 as a potential candidate for cervical cancer treatment.

Perfusion Bioreactor Culture of Bone Marrow Stromal Cells Enhances Cranial Defect Regeneration.

BACKGROUND: Cell-seeded biomaterial scaffolds have been proposed as a future option for reconstruction of bone tissue. The ability to generate larger, functional volumes of bone has been a challenge that may be addressed through the use of perfusion bioreactors. In this study, the authors investigated use of a tubular perfusion bioreactor system for the growth and differentiation of bone marrow stromal (mesenchymal stem) cells seeded onto fibrin, a highly angiogenic biomaterial. METHODS: Cells were encapsulated within fibrin beads and cultured either within a tubular perfusion bioreactor system or statically for up to 14 days. Scaffolds were analyzed for osteogenic differentiation. A rodent cranial defect model (8-mm diameter) was used to assess the bone regeneration of scaffolds cultured in the bioreactor, statically, or used immediately after formation. Immunohistochemistry was used to visualize CD31 vessel density. Micro-computed tomographic imaging was used to visualize mineral formation within the defect volume. RESULTS: Tubular perfusion bioreactor system-cultured samples showed significantly greater osteodifferentiation, indicated by an increase in VEGF expression and mineral deposition, compared with statically cultured samples. Increased expression of OPN, RUNX2, VEGF, and CD90 was seen over time in both culture methods. After implantation, bioreactor samples exhibited greater bone formation and vessel density compared with all other groups. Analysis of micro-computed tomographic images showed full union formation through the greatest diameter of the defect in all bioreactor samples and the highest levels of mineralized volume after 8 weeks. CONCLUSION: Mesenchymal stem cells encapsulated in fibrin beads and cultured in the tubular perfusion bioreactor system resulted in increased vascularization and mineralized tissue formation in vivo relative to static culture.