Xiuping Zhou

FRK controls migration and invasion of human glioma cells by regulating JNK/c-Jun signaling

The Fyn related kinase (FRK), a member of intracellular Src-related tyrosine kinases, was recently reported to function as a potent tumor suppressor in several cancer types. However, the expression level and functional significance of FRK in human malignant glioma, which is characterized by high migration and invasion potential, have never been investigated. We reported here that FRK reduced cell migration and invasion via inhibiting the c-Jun N-terminal protein kinase (JNK)/c-Jun signaling pathway in glioma cells. The mRNA and protein levels of FRK were significantly down-regulated in human primary glioma tissues. In addition, over-expression of FRK inhibited migration and invasion of glioma cells and excretion of the matrix metalloprotease 2 (MMP2), an index of migration and invasion. Furthermore, over-expression of FRK inhibited phosphorylation of JNK and c-Jun, which play important role in cell migration and invasion. Finally, the effects of FRK on cell migration and invasion and JNK/c-Jun inhibition were abolished by anisomycin, a JNK specific activator. In summary, these results clearly indicate that FRK may play a protective role against the progression of glioma by suppressing cell migration and invasion, suggesting that FRK needs to be further studied in its detail mechanism and clinical significant.

GOLPH3 regulates the migration and invasion of glioma cells though RhoA

Golgi phosphoprotein 3 (GOLPH3) has been reported to be involved in the development of several human cancers. However, the biological significance of GOLPH3 in glioma progression remains largely unknown. In this study, we report, for the first time, that downregulation of GOLPH3 led to clear reductions in glioma cell migration and invasion. In addition, downregulation of GOLPH3 inhibited the expression of the small GTPase RhoA as well as cytoskeletal reorganization, which are both required for glioma cell migration. Furthermore, we found that the observed reductions in glioma cell migration and RhoA level could be rescued by RhoA overexpression. Taken together, these results show that GOLPH3 contributes to the motility of glioma cells by regulating the expression of RhoA.

GOLPH3 promotes glioblastoma cell migration and invasion via the mTOR-YB1 pathway in vitro

The identification of genes involved in carcinogenesis and tumor progression is of great interest, since these genes might be possible as candidates for new tumor targeted therapy strategies. Our previous study shows that Golgi phosphoprotein 3 (GOLPH3) is involved in glioma cell migration and invasion, the critical characteristics of malignant gliomas. In this study, we explored the mechanism of GOLPH3 affecting cell migration and invasion and found that GOLPH3 promotes glioblastoma (GBM) cell migration and invasion via the mammalian target of rapamycin(mTOR)‐Y‐box binding protein‐1 (YB1) pathway in vitro. Both the protein levels of GOLPH3 and YB1 were up‐regulated in human glioma tissues and they exhibited direct correlation with each other. In addition, down‐regulation of GOLPH3 inhibited glioma cell migration and invasion, while over‐expression of GOLPH3 enhanced them. Meanwhile, GOLPH3 down‐regulation led to a significant decrease of YB1 level as well as mTOR activity, both required for glioma cell migration and invasion. On the contrary, YB1 level and mTOR activity increased after GOLPH3 over‐expression. YB1 down‐regulation or mTOR ATP site inhibitor INK128 treatment inhibited cell migration and invasion, similar to the effect of GOLPH3 down‐regulation. Furthermore, over‐expression of GOLPH3 induced glioma cell migration and invasion was blocked by INK128 and YB1 down‐regulation. Taken together, these results show that GOLPH3 promotes glioblastoma cell migration and invasion via the mTOR‐YB1pathway, indicating that GOLPH3‐mTOR‐YB1 pathway might be a new therapeutic target for glioma treatment.

Effects of SEMA3G on migration and invasion of glioma cells

Glioblastoma multiforme is the most aggressive type of brain tumor with a strong ability to invade and migrate into surrounding normal brain tissues, leading to high tumor recurrence and mortality. Most of class-3 semaphorins, especially SEMA3A, SEMA3B and SEMA3F, have been reported to have strong tumor inhibition ability, but the role of SEMA3G in tumor biology is largely unknown. We report here that SEMA3G possesses anti-migration and anti-invasion ability. To determine the potential effects of SEMA3G on migratory and invasive ability, we generated stable SEMA3G expression U251MG cells. We found that stably overexpressed SEMA3G inhibited the migratory and invasive behavior of U251MG cells. In addition, treatment with SEMA3G conditioned media also decreased the migratory and invasive ability of parental U251MG cells. Furthermore, SEMA3G also inhibited the activity of MMP2, an index of tumor invasion ability. Thus, our results suggest that SEMA3G inhibited tumor cell migration and invasion, which may be obtained through cell autonomous or paracrine mechanisms, and SEMA3G is a potential target for antitumor migration and invasion.

Plumbagin induces growth inhibition of human glioma cells by downregulating the expression and activity of FOXM1

Plumbagin, a natural quinonoid constituent isolated from the root of medicinal plant Plumbago zeylanica L, has exhibited anti-tumor and anti-proliferative activities in various tumor cell lines as well as in animal tumor models. However, its anticancer effects and the mechanisms underlying its suppression of glioma cell growth have not been elucidated. Oncogenic transcription factor Forkhead Box M1 (FOXM1) has garnered particular interest in recent years as a potential target for the prevention and/or therapeutic intervention in glioma, nevertheless, less information is currently available regarding FOXM1 inhibitor. Here, we reported that plumbagin could effectively inhibit cell proliferation, migration and invasion and induce apoptosis of glioma cells. Cell cycle assay showed that plumbagin induced G2/M arrest. Interestingly, we found that plumbagin decreased the expression of FOXM1 both at mRNA level and protein level. Plumbagin also inhibited the transactivation ability of FOXM1, resulting in down-regulating the expression of FOXM1 downstream target genes, such as cyclin D1, Cdc25B, survivin, and increasing the expression of p21CIP1 and p27KIP1. Most importantly, down-regulation of FOXM1 by siFOXM1 transfection enhanced plumbagin-induced change in viability. On the contrary, over-expression of FOXM1 by cDNA transfection reduced plumbagin-induced glioma cell growth inhibition. These results suggest that plumbagin exhibits its anticancer activity partially by inactivation of FOXM1 signaling pathway in glioma cells. Our findings indicate that plumbagin may be considered as a potential natural FOXM1 inhibitor, which could contribute to the development of new anticancer agent for therapy of gliomas.

Mst1 regulates glioma cell proliferation via the AKT/mTOR signaling pathway

Mammalian sterile 20-like 1 (Mst1), an upstream serine/threonine-specific protein kinase of the Hippo pathway, is reported to play important roles in tumor suppression and organ size regulation in mammals via regulating cell proliferation and survival. However, whether it is involved in the pathogenesis of malignant gliomas remains poorly understood. Therefore, in the present work, we examined the effect and mechanism of Mst1 on the proliferation and apoptosis of malignant glioma cells. The cell proliferation and growth of glioma cells were examined by EdU incorporation and CCK-8 assay. In addition, the cell apoptosis was assessed by flow cytometry. We found that down-regulation of Mst1 promoted glioma cell proliferation and growth, but inhibited the cell apoptosis. Consistent with this, over-expression of Mst1 inhibited glioma cell proliferation and growth. Interestingly, Mst1 did not affect the phosphorylation of YAP1, the key downstream molecule of Hippo pathway. However, Mst1 was found to bind to AKT in glioma cell and negatively regulated AKT and mTOR activity. Finally, the increased cell proliferation rate induced by Mst1 down-regulation was partially abolished by down-regulation of AKT1. Meanwhile, glioma cell growth inhibition induced by Mst1 over-expression was partially rescued by over-expression of AKT1. Taken together, these findings suggest that Mst1 regulates proliferation of glioma cells via AKT/mTOR signaling pathway.

Expression and significance of Hippo/YAP signaling in glioma progression

Dysregulation of Hippo/YAP signaling leads to aberrant cell growth and neoplasia. Although the roles and regulation of Hippo/YAP signaling were extensively studied in cancer biology recently, study systematically checking the expression pattern of core components of this pathway at the tumor tissue level remains lacking. In this study, we thoroughly examined the profile of core components of Hippo/YAP signaling in patient specimens both at the mRNA and at protein levels. We found that the mRNA level of YAP1/TAZ and their target genes, CRY61, CTGF, and BIRC5, was remarkably amplified in glioma tissues. Consistently, the protein level of YAP1/TAZ increased and meanwhile those of p-YAP1/p-TAZ and LATS1/2 decreased in gliomas. Unexpectedly, both the mRNA and protein levels of MST1/2 increased in the glioma tissues, inconsistent with its presumed tumor suppressor identity. In addition, over-expression of LATS2 decreased, while over-expression of YPA1 increased the cell proliferation ability. Furthermore, based on the data from the free public database, YAP1/TAZ and BIRC5 were positively associated with the prognosis of glioma patients, while LATS1/2 exhibited negative correlation with the glioma patient prognosis. Collectively, we deduce that, in glioma tissue context, MST1/2 may not be the essential component of the hippo/YAP pathway. Moreover, our findings uncover a new evidence supporting that YAP1/TAZ-BIRC5 might be abnormally activated due to LATS1/2 down-regulation, which in turn promote the occurrence and development of gliomas, paving the way to identify the potential therapeutic molecular target for gliomas.

Research progress in NOS1AP in neurological and psychiatric diseases

Nitric Oxide Synthase 1 Adaptor Protein (NOS1AP, previously named CAPON) was firstly identified in rat brain in 1998. Structurally, NOS1AP consists of a phosphotyrosine-binding (PTB) domain at its N-terminal and a PDZ (PSD-95/discs-large/ZO-1) ligand motif at its C-terminal. The PTB domain of NOS1AP mediates the interactions with Dexras1, scribble, and synapsins. The PDZ ligand motif of NOS1AP binds to the PDZ domain of NOS1, the enzyme responsible for nitric oxide synthesis in the nervous system. NOS1AP is implicated in Dexras1 activation, neuronal nitric oxide production, Hippo pathway signaling, and dendritic development through the association with these important partners. An increasing body of evidence is pointing to the significant roles of NOS1AP in excitotoxic neuronal damage, traumatic nervous system injury, bipolar disorder, and schizophrenia. However, the study progress in NOS1AP in neurological or psychiatric diseases, has not been systematically reviewed. Here we introduce the expression, structure, and isoforms of NOS1AP, then summarize the physiological roles of NOS1AP, and discuss the relationships between NOS1AP alterations and the pathophysiology of some neurological and psychiatric disorders. The review will promote the further investigation of NOS1AP in brain disorders and the development of drugs targeting the NOS1AP PTB domain or PDZ-binding motif in the future.

FRK Inhibits Migration and Invasion of Human Glioma Cells by Promoting N-cadherin/β-catenin Complex Formation

Fyn-related kinase (FRK), a member of Src-related tyrosine kinases, is recently reported to function as a potent tumor suppressor in several cancer types. Our previous study has also shown that FRK over-expression inhibited the migration and invasion of glioma cells. However, the mechanism of FRK effect on glioma cell migration and invasion, a feature of human malignant gliomas, is still not clear. In this study, we found that FRK over-expression increased the protein level of N-cadherin, but not E-cadherin. Meanwhile, FRK over-expression promoted β-catenin translocation to the plasma membrane, where it formed complex with N-cadherin, while decreased β-catenin level in the nuclear fraction. In addition, down-regulation of N-cadherin by siRNA promoted the migration and invasion of glioma U251 and U87 cells and abolished the inhibitory effect of FRK on glioma cell migration and invasion. In summary, these results indicate that FRK inhibits migration and invasion of human glioma cells by promoting N-cadherin/β-catenin complex formation.

Protein kinase D2 promotes the proliferation of glioma cells by regulating Golgi phosphoprotein 3

Protein kinase D2 (PKD2) has been demonstrated to promote tumorigenesis in many types of cancers. However, how PKD2 regulates cancer cell growth is largely unknown. In this study, we found that over-expression of PKD2 promoted glioma cell growth but down-regulation of PKD2 inhibited it. Further investigation indicated that PKD2 down-regulation decreased the protein level of Golgi phosphoprotein 3(GOLPH3) as well as p-AKT level. On the contrary, over-expression of PKD2 increased the protein level of GOLPH3 and p-AKT. In addition, GOLPH3 exhibited similar effect on glioma cell growth to that of PKD2. Importantly, GOLPH3 down-regulation partially abolished glioma cell proliferation induced by PKD2 over-expression, while over-expression of GOLPH3 also partially rescued the inhibition effect of PKD2 down-regulation on glioma cell growth. Interestingly, the level of PKD2 and GOLPH3 significantly increased and was positively correlated in a cohort of glioma patients, as well as in patients from TCGA database. Taken together, these results reveal that PKD2 promotes glioma cell proliferation by regulating GOLPH3 and then AKT activation. Our findings indicate that both PKD2 and GOLPH3 play important roles in the progression of human gliomas and PKD2-GOLPH3-AKT signaling pathway might be a potential glioma therapeutic target.