Zoledronic acid prevents the tumor-promoting effects of mesenchymal stem cells via MCP-1 dependent recruitment of macrophages

Zoledronic acid (ZA) has been tested in clinical trials as an additive therapy for early-stage breast cancer. However, the mechanism by which ZA exerts its antitumor activity is still unclear. The aim of this study is to investigate whether the prevention of tumor growth by ZA is through regulating the mesenchymal stem cells (MSC)-monocyte chemotactic protein 1 (MCP-1)-macrophages axis in the tumor microenvironment.To address this issue, MDA-MB-231-FLUC human breast cancer cells were cultured and injected either alone, or coupled with MSC into the mammary fat pads of nude mice. MSC were treated with either ZA or untreated. Tumor growth was determined by using an in vivo bioluminescence imaging (BLI) and the tumor-associated macrophages (TAMs) in tumor tissues were immunohistochemically analyzed by using CD206 antibody. The effects of ZA on the cytokine related gene expression of MSC were assessed by using real-time PCR.In this study, we found that ZA-treated mice showed a significant delay in tumor growth. In addition, our data revealed that ZA weakened the ability of MSC to promote tumor growth by impairing TAMs recruitment and tumor vascularization. Furthermore, it was found that ZA decreased MCP-1 expression of MSC, and therefore reduced the recruitment of TAMs to the tumor sites and hence inhibited the tumor growth.Altogether, our study demonstrated ZA can prevent the tumor-promoting effects of MSC. The antitumor effects of ZA were caused by decreasing the MCP-1 expression of MSC, which further decreased the infiltration of TAMs into tumor sites, and therefore inhibited the tumor growth.     

Suppression of mTOR pathway and induction of autophagy-dependent cell death by cabergoline

Cabergoline (CAB), the first-line drug for treatment of prolactinomas, is effective in suppressing prolactin hypersecretion, reducing tumor size, and restoring gonadal function. However, mechanisms for CAB-mediated tumor shrinkage are largely unknown. Here we report a novel cytotoxic mechanism for CAB. CAB induced formation of autophagosome in rat pituitary tumor MMQ and GH3 cells at the early stage through inhibiting mTOR pathway, resulting in higher conversion rates of LC3-I to LC3-II, GFP-LC3 aggregation, and increased autophagosome formation. Interestingly, CAB treatment augmented lysosome acidification and resulted in impaired proteolytic degradation within autolysosomes. This blocked the autophagic flux, leading to the accumulation of p62 aggregation and undigested autolysosomes. Knockdown of ATG7, ATG5, or Becn1, could significantly rescue the CAB-mediated cell death of MMQ cells (p < 0.05). CAB-induced autophagy and blockade of autophagy flux participated in antitumoral action in vivo. In conclusion, our study provides evidence that CAB concomitantly induces autophagy and inhibits the autophagic flux, leading to autophagy-dependent cell death. These findings elucidate novel mechanisms for CAB action.     

Subpathway-GMir: identifying miRNA-mediated metabolic subpathways by integrating condition-specific genes,microRNAs, and pathway topologies

MicroRNAs (miRNAs) regulate disease-relevant metabolic pathways. However, most current pathway identification methods fail to consider miRNAs in addition to genes when analyzing pathways. We developed a powerful method called Subpathway-GMir to construct miRNA-regulated metabolic pathways and to identify miRNA-mediated subpathways by considering condition-specific genes, miRNAs, and pathway topologies. We used Subpathway-GMir to analyze two liver hepatocellular carcinomas (LIHC), one stomach adenocarcinoma (STAD), and one type 2 diabetes (T2D) data sets. Results indicate that Subpathway-GMir is more effective in identifying phenotype-associated metabolic pathways than other methods and our results are reproducible and robust. Subpathway-GMir provides a flexible platform for identifying abnormal metabolic subpathways mediated by miRNAs, and may help to clarify the roles that miRNAs play in a variety of diseases. The Subpathway-GMir method has been implemented as a freely available R package.     

Loss of miR-200b promotes invasion via activating the Kindlin-2/integrin β1/AKT pathway in esophageal squamous cell carcinoma: An E-cadherin-independent mechanism

Our previous studies have shown that loss of miR-200b enhances the invasiveness of esophageal squamous cell carcinoma (ESCC) cells. However, whether the miR-200-ZEB1/2-E-cadherin regulatory cascade, a master regulator of epithelial-to-mesenchymal transition (EMT), is involved in the regulation of ESCC invasion remains elusive. Here, we show that miR-200b represses ESCC cell invasion in vivo without altering the expression of E-cadherin and vimentin, two surrogate markers of EMT. However, an inverse correlation was observed between the expression levels of miR-200b and ZEB1/2 in both ESCC cell lines (n = 7, P < 0.05) and ESCC tumor samples (n = 88, P < 0.05). Methylation of E-cadherin gene was found to block the regulation of E-cadherin by the miR-200b-ZEB1/2 axis, indicating that an E-cadherin-independent mechanism can mediate the biological function of miR-200b in ESCC. We revealed that miR-200b suppresses the integrin β1-AKT pathway via targeting Kindlin-2 to mitigate ESCC cell invasiveness. In two independent cohorts of ESCC samples (n = 20 and n = 53, respectively), Kindlin-2 expression positively correlated with the activation status of both the integrin signaling pathway and the PI3K-AKT signaling pathway (both P < 0.01). These data highlight that suppression of the Kindlin-2-integrin β1-AKT regulatory axis is an alternative mechanism underlying the tumor suppressor function of miR-200b in ESCC.     

Tenascin-C expression is associated with poor prognosis in hepatocellular carcinoma (HCC) patients and the inflammatory cytokine TNF-α-induced TNC expression promotes migration in HCC cells

Although tenascin-c (TNC) in inflammatory microenvironment contributes to progression in some tumors, its role in hepatocellular carcinoma (HCC) in metastasis and the mechanism by which TNC expression is regulated in HCC cells are elusive. In this study, we examined TNC expression in 100 HCC tissue samples by immunohistochemistry and compared which between the groups with or without metastasis. TNC expression was higher in metastatic HCC tissues than that in the non-metastatic HCC tissues, which was associated with the Knodell inflammation scores. Importantly, high level of TNC expression was associated with lower survival rate and shorter survival time in the HCC patients. We then investigated the mechanism by which TNC expression is regulated in HCC cells with an in vitro cell culture system. The recombinant TNF-α and conditioned medium from macrophages induced TNC expression at both mRNA and protein levels in HepG2 cells. The induction of TNC expression by conditioned medium from macrophages was suppressed by a TNF-α neutralizing antibody. TNF-α-promoted cell migration was inhibited by a TNC siRNA. In addition, TNF-α-induced TNC expression was blocked by a NF-κB pathway inhibitor. These results suggest that TNF-α in the tumor microenvironment induces TNC expression in HCC cells through the NF-κB pathway, which in turn, promotes HCC cell migration. Thus, TNC may play an important role in promoting HCC metastasis and TNC expression could be a predictive factor for poor prognosis in HCC patients.     

左归降糖解郁方对糖尿病并发抑郁症模型大鼠学习记忆及海马超微结构的影响

目的研究左归降糖解郁方对糖尿病并发抑郁症大鼠学习记忆和海马超微结构的影响。方法采用高脂灌胃、链脲佐菌素注射(38mg/kg)和慢性应激联合的方法建立糖尿病并发抑郁症动物模型,并随机分为5组:糖尿病并发抑郁症模型组,阳性药(二甲双胍0.18g/kg+氟西汀1.8mg/kg)组,左归降糖解郁方高、中、低剂量(20.53 g/kg,10.26 g/kg,5.13g/kg)组,以正常组为对照。给药4周后,采用Morris水迷宫进行行为学评价,采用透射电镜观察海马细胞超微结构。结果Morris水迷宫实验,与正常组比较,模型组大鼠逃避潜伏期(EL)明显延长,空间探索时间(SET)明显缩短(P0.05);与模型组比较,阳性药组和高剂量组大鼠EL明显缩短,SET明显延长(P0.05)。电镜下可见,正常组大鼠海马神经元细胞形态规则,染色质分布均匀,线粒体内部嵴清晰可见;模型组大鼠海马神经元胞体肿胀,内质网脱颗粒严重,线粒体内嵴消失;给予左归降糖解郁方高剂量后,海马神经元损伤程度减轻,部分胞内可见线粒体。结论左归降糖解郁方可明显改善模型大鼠的学习记忆功能,其可能通过保护海马神经元结构发挥治疗作用。