Adenosylhomocysteinase plays multiple roles in maintaining the identity and pluripotency of mouse embryonic stem cells†.

Adenosylhomocysteinase (AHCY), a key enzyme in the methionine cycle, is essential for the development of embryos and the maintenance of mouse embryonic stem cells (mESCs). However, the precise underlying mechanism of Ahcy in regulating pluripotency remains unclear. As the only enzyme that can hydrolyze S-adenosylhomocysteine in mammals, AHCY plays a critical role in the metabolic homeostasis, epigenetic remodeling, and transcriptional regulation. Here, we identified Ahcy as a direct target of OCT4 and unveiled that AHCY regulates the self-renewal and differentiation potency of mESCs through multiple mechanisms. Our study demonstrated that AHCY is required for the metabolic homeostasis of mESCs. We revealed the dual role of Ahcy in both transcriptional activation and inhibition, which is accomplished via the maintenance of H3K4me3 and H3K27me3, respectively. We found that Ahcy is required for H3K4me3-dependent transcriptional activation in mESCs. We also demonstrated that AHCY interacts with polycomb repressive complex 2 (PRC2), thereby maintaining the pluripotency of mESCs by sustaining the H3K27me3-regulated transcriptional repression of related genes. These results reveal a previously unrecognized OCT4-AHCY-PRC2 axis in the regulation of mESCs' pluripotency and provide insights into the interplay between transcriptional factors, cellular metabolism, chromatin dynamics and pluripotency regulation.

Moesin facilitates metastasis of hepatocellular carcinoma cells by improving invadopodia formation and activating ß-catenin/MMP9 axis.

Moesin has been proved to be implicated in invasiveness and metastasis in many other cancers, but unclear in HCC. Thus, this study was performed to investigate the clinical significance of moesin and its biological functions in HCC. The results showed that moesin was significantly up-regulated in HCC tissues and was an independent prognostic factor for predicting the recurrence of HCC patients, postoperatively. Furthermore, we also demonstrated that moesin promoted the migration and invasion of HCC cells in vitro and in vivo. And the mechanism studies indicated that moesin overexpression increased the formation of invadopodia and improved the activation of ß-catenin/MMP9 axis. Taken together, our findings revealed that moesin acted as an important onco-protein participating in the metastasis of HCC.

Ku80 negatively regulates the expression of OCT4 via competitive binding to SALL4 and promoting lysosomal degradation of OCT4.

SALL4 and OCT4, along with other pluripotency-associated transcription factors, play critical roles in maintaining embryonic stem cell pluripotency and self-renewal. Ku80 is a component of the protein complex called DNA-dependent protein kinase, which mainly involved in DNA double-strand break repair. In this study, we show evidence that Ku80 physically interacted with SALL4. The interaction competitively disrupts the SALL4-OCT4 complex and result in OCT4 lysosomal degradation. Finally, Ku80 inhibits self-renewal and metastasis of hepatocellular carcinoma cells through breaking the SALL4-OCT4 interactions and down-regulating the expression of OCT4. Our study reveal novel function of Ku80 in stemness maintaining of cancer stem cells via its interaction with SALL4 and highlight the double-sidedness of Ku80 as an anti-cancer target.

Inflammatory Micro-environment Contributes to Stemness Properties and Metastatic Potential of HCC via the NF-κB/miR-497/SALL4 Axis.

Increasing evidence has demonstrated the essential role of inflammatory micro-environment in tumorigenesis and tumor progression. Some cancer cells in tumor maintain typical stemness properties and, with the capacity of self-renewal, are thought to be crucial for the initiation and maintenance of tumors as well as their metastasis. Although both inflammatory micro-environment and stemness properties played crucial roles in tumor initiation and development, currently it is still unclear whether and how the inflammatory micro-environment promotes cancer stemness properties. Here, we show the first evidence that the inflammatory micro-environment promotes the stemness properties and metastatic potential of hepatocellular carcinoma (HCC) via the NF-κB/miR-497/SALL4 axis. We discover that miR-497 directly targets SALL4, negatively regulates its expression, and further inhibits the self-renewal and metastasis of HCC; more importantly, inflammatory factor TNF-α inhibits the expression of miR-497 via NF-kB-mediated negative transcriptional regulation and simultaneously upregulates the expression of SALL4 and promotes the self-renewal and metastasis phenotypes of HCC cells. Moreover, lower expression of miR-497 is significantly associated with poor prognosis in HCC patients. Taken together, our findings not only revealed a novel signaling pathway (NF-κB/miR-497/SALL4 axis) to connect inflammation with stemness properties, and clarified the molecular mechanisms underlying the inflammation-mediated self-renewal and metastasis phenotypes, but also provided novel molecular targets for developing new anticancer strategies.