Exploring the mechanism of resistance to sorafenib in two hepatocellular carcinoma cell lines.

Sorafenib has long been the only approved systemic therapy for advanced hepatocellular carcinoma (HCC), but most patients show primary or acquired drug resistance. In the present study, RNA was extracted from sorafenib-resistant and -sensitive clones of the HCC cell lines HepG2 and Huh7. Protein-protein interaction networks of the up- and down-regulated genes common to the two sorafenib-resistant cell lines were extracted and subjected to modular analysis in order to identify functional modules. Functional enrichment analysis showed the modules were involved in different biological processes and pathways. These results indicate that sorafenib resistance in HCC is complicated and heterogeneous. The potential regulators of each functional module, including transcription factors, microRNAs and long non-coding RNAs, were explored to construct a comprehensive transcriptional regulatory network related to sorafenib resistance in HCC. Our results provide new insights into sorafenib resistance of HCC at the level of transcriptional regulation.

Bone-derived Nestin-positive mesenchymal stem cells improve cardiac function via recruiting cardiac endothelial cells after myocardial infarction.

BACKGROUND: Bone-derived mesenchymal stem cell (BMSC) transplantation has been reported to be effective for the treatment of ischemic heart disease, but whether BMSCs are the optimal cell type remains under debate. Increasing numbers of studies have shown that Nestin, an intermediate filament protein, is a potential marker for MSCs, which raises the question of whether Nestin+ cells in BMSCs may play a more crucial role in myocardial repair. METHODS: Nestin+ cells were isolated using flow cytometry by gating for CD45- Ter119- CD31- cells from the compact bone of Nestin-GFP transgenic mice, expressing GFP driven by the Nestin promoter. Colony-forming and proliferative curve assays were conducted to determine the proliferative capacity of these cells, while qRT-PCR was used to analyze the mRNA levels of relative chemokines and growth factors. Cardiac endothelial cell (CEC) recruitment was assessed via a transwell assay. Moreover, permanent ligation of the left anterior descending (LAD) coronary artery was performed to establish an acute myocardial infarction (AMI) mouse model. After cell transplantation, conventional echocardiography was conducted 1 and 4 weeks post-MI, and hearts were harvested for hematoxylin-and-eosin (HE) staining and immunofluorescence staining 1 week post-MI. Further evaluation of paracrine factor levels and administration of a neutralizing antibody (TIMP-1, TIMP-2, and CXCL12) or a CXCR4 antagonist (AMD3100) in MI hearts were performed to elucidate the mechanism involved in the chemotactic effect of Nestin+ BMSCs in vivo. RESULTS: Compared with Nestin- BMSCs, a greater proliferative capacity of Nestin+ BMSCs was observed, which further exhibited moderately high expression of chemokines instead of growth factors. More CEC recruitment in the Nestin+ BMSC-cocultured group was observed in vitro, while this effect was obviously abolished after treatment with neutralizing antibodies against TIMP-1, TIMP-2, or CXCL12, and more importantly, blocking the CXCL12/CXCR4 axis with a AMD3100 significantly reduced the chemotactic effect of Nestin+ BMSCs. After transplantation into mice exposed to myocardial infarction (MI), Nestin+ BMSC-treated mice showed significantly improved survival and left ventricular function compared with Nestin- BMSC-treated mice. Moreover, endogenous CECs were markedly increased, and chemokine levels were significantly higher, in the infarcted border zone with Nestin+ BMSC treatment. Meanwhile, neutralization of each TIMP-1, TIMP-2, or CXCL12 in vivo could reduce the left ventricular function at 1 and 4 weeks post-MI; importantly, the combined use of these three neutralizing antibodies could make a higher significance on cardiac function. Finally, blocking the CXCL12/CXCR4 axis with AMD3100 significantly reduced the left ventricular function and greatly inhibited Nestin+ BMSC-induced CEC chemotaxis in vivo. CONCLUSIONS: These results suggest that Nestin+ BMSC transplantation can improve cardiac function in an AMI model by recruiting resident CECs to the infarcted border region via the CXCL12/CXCR4 chemokine pathway. And we demonstrated that Nestin+BMSC-secreted TIMP-1/2 enhances CXCL12(SDF1α)/CXCR4 axis-driven migration of endogenous Sca-1+ endothelial cells in ischemic heart post-AMI. Taken together, our results show that Nestin is a useful marker for the identification of functional BMSCs and indicate that Nestin+ BMSCs could be a better therapeutic candidate for cardiac repair.