Hippo Pathway in Schwann Cells and Regeneration of Peripheral Nervous System.

Hippo pathway is an evolutionarily conserved signaling pathway comprising a series of MST/LATS kinase complexes. Its key transcriptional coactivators YAP and TAZ regulate transcription factors such as TEAD family to direct gene expression. The regulation of Hippo pathway, especially the nuclear level change of YAP and TAZ, significantly influences the cell fate switching from proliferation to differentiation, regeneration, and postinjury repair. This review outlines the main findings of Hippo pathway in peripheral nerve development, regeneration, and tumorigenesis, especially the studies in Schwann cells. We also summarize other roles of Hippo pathway in damage repair of the peripheral nerve system and discuss the potential future research which probably contributes to novel therapeutic strategies.

MicroRNA-1205 promotes breast cancer cell metastasis by regulating epithelial-to-mesenchymal transition via targeting of CDK3.

Metastasis poses a huge obstacle to the survival of breast cancer patients. The microRNA miR-1205 acts as a tumor suppressor in various cancers, but its roles in breast cancer and metastasis remain unclear. To elucidate its function in breast cancer progression, we analyzed miR-1205 expression in human tumor samples and carried out a series of functional studies in in vitro and in vivo. miR-1205 was expressed more highly in metastatic breast tumor samples than in non-metastatic samples and was associated with lymph node metastasis, clinical stage, and poor prognosis. Moreover, miR-1205 promoted breast cancer cell invasiveness in vitro and metastasis in mice by directly targeting CDK3 and reducing CDK3 protein levels. We also showed that CDK3 interacts with Snail protein, inducing Snail degradation via the ubiquitin-proteasome system and potentially affecting epithelial-to-mesenchymal transition. Furthermore, analysis of clinical tissue samples indicated that CDK3 and miR-1205 levels were inversely correlated in lymph node metastasis-positive primary tumors. This study demonstrated the pro-metastatic role of miR-1205 in breast cancer, mediated via a novel miR-1205/CDK3/Snail axis. Moreover, we identified miR-1205 and CDK3 as potential markers of invasion and progression in breast cancer.

CBX4 deletion promotes tumorigenesis under KrasG12D background by inducing genomic instability.

Chromobox protein homolog 4 (CBX4) is a component of the Polycomb group (PcG) multiprotein Polycomb repressive complexes 1 (PRC1), which is participated in several processes including growth, senescence, immunity, and tissue repair. CBX4 has been shown to have diverse, even opposite functions in different types of tissue and malignancy in previous studies. In this study, we found that CBX4 deletion promoted lung adenocarcinoma (LUAD) proliferation and progression in KrasG12D mutated background. In vitro, over 50% Cbx4L/L, KrasG12D mouse embryonic fibroblasts (MEFs) underwent apoptosis in the initial period after Adeno-Cre virus treatment, while a small portion of survival cells got increased proliferation and transformation abilities, which we called selected Cbx4-/-, KrasG12D cells. Karyotype analysis and RNA-seq data revealed chromosome instability and genome changes in selected Cbx4-/-, KrasG12D cells compared with KrasG12D cells. Further study showed that P15, P16 and other apoptosis-related genes were upregulated in the primary Cbx4-/-, KrasG12D cells due to chromosome instability, which led to the large population of cell apoptosis. In addition, multiple pathways including Hippo pathway and basal cell cancer-related signatures were altered in selected Cbx4-/-, KrasG12D cells, ultimately leading to cancer. We also found that low expression of CBX4 in LUAD was associated with poorer prognosis under Kras mutation background from the human clinical data. To sum up, CBX4 deletion causes genomic instability to induce tumorigenesis under KrasG12D background. Our study demonstrates that CBX4 plays an emerging role in tumorigenesis, which is of great importance in guiding the clinical treatment of lung adenocarcinoma.