Ezrin-radixin-moesin-binding phosphoprotein-50 regulates EGF-induced AKT activation through interaction with EGFR and PTEN

KBTBD7 promotes non-small cell lung carcinoma progression by enhancing ubiquitin-dependent degradation of PTEN

The Kelch repeat and BTB domain containing 7 (KBTBD7) was first cloned in 2010. Its function as a transcriptional activator and a substrate adaptor during the ubiquitination process was soon found. KBTBD7 was shown to be involved in excessive inflammation after myocardial infarction, brain development, and neurofibromin stability. However, studies on the role of KBTBD7 in solid tumors, especially lung cancer, are still lacking. Therefore, in this study, we investigate the role of KBTBD7 in non-small cell lung cancer (NSCLC). Immunohistochemical staining of 102 paired NSCLC and peritumoral normal specimens indicated that KBTBD7 was highly expressed in NSCLC tissues and positively correlated with the histological type, P-TNM stage, lymph node metastasis, and tumor size. KBTBD7 was also well-expressed in NSCLC cell lines, and downregulation of KBTBD7 resulted in inhibition of NSCLC cell proliferation and invasion. Further investigation showed that KBTBD7 enhanced ubiquitin-dependent degradation of PTEN, thus activating EGFR/PI3K/AKT signaling and promoting NSCLC cell proliferation and invasion by regulating CCNE1, CDK4, P27, ZEB-1, Claudin-1, ROCK1, MMP-9, and E-cadherin protein levels. Our results indicate that KBTBD7 may be a potential therapeutic target for the treatment of NSCLC.

MicroRNA: a novel implication for damage and protection against ionizing radiation

Ionizing radiation (IR) is a form of high energy. It poses a serious threat to organisms, but radiotherapy is a key therapeutic strategy for various cancers. It is significant to reduce radiation injury but maximize the effect of radiotherapy. MicroRNAs (miRNAs) are posttranscriptionally regulatory factors involved in cellular radioresponse. In this review, we show how miRNAs regulate important genes on cellular response to IR-induced damage and how miRNAs participate in IR-induced carcinogenesis. Additionally, we summarize the experimental and clinical evidence for miRNA involvement in radiotherapy and discuss their potential for improvement of radiotherapy. Finally, we highlight the role that miRNAs play in accident exposure to IR or radiotherapy as predictive biomarker. miRNA therapeutics have shown great perspective in radiobiology; miRNA may become a novel strategy for damage and protection against IR.

ANXA1 affects murine hair follicle growth through EGF signaling pathway

Annexin A1 (ANXA1), a calcium-dependent phospholipid binding protein expressed in animals, plants and microorganisms, participates in various cellular physiological activities. Previous proteomics analysis indicates that the level of ANXA1 in mice dorsal skin changes during hair growth cycle, we speculate that ANXA1 may play an important role in hair follicle (HF) development. Thus, Anxa1 knock-out (KO) and over-expression (OE) mice were constructed to test its function. Our results showed that in addition to the diameter of HF and hair shaft, ANXA1 could participate in hair growth by affecting the density of HF, and the proliferation of hair follicle stem cells (HFSCs). Meanwhile, molecular analysis showed that EGF signaling pathway is involved in the function of ANXA1. The expression of Anxa1 is negatively correlated with the levels of Egf, Notch1, Mkk7, and phosphorylated AKT1 and ERK/2 proteins. The levels of Egf, Notch1, Mkk7 and phosphorylation of AKT1 and ERK/2 increased in Anxa1 KO mice but decreased in Anxa1 OE mice. Taken together, our results suggested that ANXA1 could affect the hair growth by regulating the HFSCs proliferation through EGF signaling pathway.

Loss-of-function of EBP50 is a new cause of hereditary peripheral neuropathy: EBP50 functions in peripheral nerve system

Finding causative genetic mutations is important in the diagnosis and treatment of hereditary peripheral neuropathies. This study was conducted to find new genes involved in the pathophysiology of hereditary peripheral neuropathy. We identified a new mutation in the EBP50 gene, which is co-segregated with neuropathic phenotypes, including motor and sensory deficit in a family with Charcot-Marie-Tooth disease. EBP50 is known to be important for the formation of microvilli in epithelial cells, and the discovery of this gene mutation allowed us to study the function of EBP50 in the nervous system. EBP50 was strongly expressed in the nodal and paranodal regions of sciatic nerve fibers, where Schwann cell microvilli contact the axolemma, and at the growth tips of primary Schwann cells. In addition, EBP50 expression was decreased in mouse models of peripheral neuropathy. Knockout mice were used to study EBP50 function in the peripheral nervous system. Interestingly motor function deficit and abnormal histology of nerve fibers were observed in EBP50^+/- heterozygous mice at 12 months of age, but not 3 months. in vitro studies using Schwann cells showed that NRG1-induced AKT activation and migration were significantly reduced in cells overexpressing the I325V mutant of EBP50 or cells with knocked-down EBP50 expression. In conclusion, we show for the first time that loss of function due to EBP50 gene deficiency or mutation can cause peripheral neuropathy.

Phosphorylation of NHERF1 S279 and S301 differentially regulates breast cancer cell phenotype and metastatic organotropism

Metastatic cancer cells are highly plastic for the expression of different tumor phenotype hallmarks and organotropism. This plasticity is highly regulated but the dynamics of the signaling processes orchestrating the shift from one cell phenotype and metastatic organ pattern to another are still largely unknown. The scaffolding protein NHERF1 has been shown to regulate the expression of different neoplastic phenotypes through its PDZ domains, which forms the mechanistic basis for metastatic organotropism. This reprogramming activity was postulated to be dependent on its differential phosphorylation patterns. Here, we show that NHERF1 phosphorylation on S279/S301 dictates several tumor phenotypes such as in vivo invasion, NHE1-mediated matrix digestion, growth and vasculogenic mimicry. Remarkably, injecting mice with cells having differential NHERF1 expression and phosphorylation drove a shift from the predominantly lung colonization (WT NHERF1) to predominately bone colonization (double S279A/S301A mutant), indicating that NHERF1 phosphorylation also acts as a signaling switch in metastatic organotropism.