Glia maturation factor promotes contact inhibition in cancer cells

Real-Time Noninvasive Bioluminescence, Ultrasound and Photoacoustic Imaging in NFκB-RE-Luc Transgenic Mice Reveal Glia Maturation Factor-Mediated Immediate and Sustained Spatio-Temporal Activation of NFκB Signaling Post-Traumatic Brain Injury in a Gender-Specific Manner

Neurotrauma especially traumatic brain injury (TBI) is the leading cause of death and disability worldwide. To improve upon the early diagnosis and develop precision-targeted therapies for TBI, it is critical to understand the underlying molecular mechanisms and signaling pathways. The transcription factor, nuclear factor kappa B (NFκB), which is ubiquitously expressed, plays a crucial role in the normal cell survival, proliferation, differentiation, function, as well as in disease states like neuroinflammation and neurodegeneration. Here, we hypothesized that real-time noninvasive bioluminescence molecular imaging allows rapid and precise monitoring of TBI-induced immediate and rapid spatio-temporal activation of NFκB signaling pathway in response to Glia maturation factor (GMF) upregulation which in turn leads to neuroinflammation and neurodegeneration post-TBI. To test and validate our hypothesis and to gain novel mechanistic insights, we subjected NFκB-RE-Luc transgenic male and female mice to TBI and performed real-time noninvasive bioluminescence imaging (BLI) as well as photoacoustic and ultrasound imaging (PAI). Our BLI data revealed that TBI leads to an immediate and sustained activation of NFκB signaling. Further, our BLI data suggest that especially in male NFκB-RE-Luc transgenic mice subjected to TBI, in addition to brain, there is widespread activation of NFκB signaling in multiple organs. However, in the case of the female NFκB-RE-Luc transgenic mice, TBI induces a very specific and localized activation of NFκB signaling in the brain. Further, our microRNA data suggest that TBI induces significant upregulation of mir-9-5p, mir-21a-5p, mir-34a-5p, mir-16-3p, as well as mir-155-5p within 24 h and these microRNAs can be successfully used as TBI-specific biomarkers. To the best of our knowledge, this is one of the first and unique study of its kind to report immediate and sustained activation of NFκB signaling post-TBI in a gender-specific manner by utilizing real-time non-invasive BLI and PAI in NFκB-RE-Luc transgenic mice. Our study will prove immensely beneficial to gain novel mechanistic insights underlying TBI, unravel novel therapeutic targets, as well as enable us to monitor in real-time the response to innovative TBI-specific precision-targeted gene and stem cell-based precision medicine.

Glia maturation factor-β: a potential therapeutic target in neurodegeneration and neuroinflammation

Glia maturation factor-β (GMFB) is considered to be a growth and differentiation factor for both glia and neurons. GMFB has been found to be upregulated in several neuroinflammation and neurodegeneration conditions. It may function by mediating apoptosis and by modulating the expression of superoxide dismutase, granulocyte-macrophage colony-stimulating factor, and neurotrophin. In this review, we mainly discussed the role of GMFB in several neuroinflammatory and neurodegenerative diseases. On review of the literature, we propose that GMFB may be a promising therapeutic target for neuroinflammatory and neurodegenerative diseases.

Cofilin-1 and Other ADF/Cofilin Superfamily Members in Human Malignant Cells

Identification of actin-depolymerizing factor homology (ADF-H) domains in the structures of several related proteins led first to the formation of the ADF/cofilin family, which then expanded to the ADF/cofilin superfamily. This superfamily includes the well-studied cofilin-1 (Cfl-1) and about a dozen different human proteins that interact directly or indirectly with the actin cytoskeleton, provide its remodeling, and alter cell motility. According to some data, Cfl-1 is contained in various human malignant cells (HMCs) and is involved in the formation of malignant properties, including invasiveness, metastatic potential, and resistance to chemotherapeutic drugs. The presence of other ADF/cofilin superfamily proteins in HMCs and their involvement in the regulation of cell motility were discovered with the use of various OMICS technologies. In our review, we discuss the results of the study of Cfl-1 and other ADF/cofilin superfamily proteins, which may be of interest for solving different problems of molecular oncology, as well as for the prospects of further investigations of these proteins in HMCs.

BMI-1 suppresses contact inhibition and stabilizes YAP in Ewing sarcoma

The polycomb group family protein BMI-1 is overexpressed by and functions as an oncogene in many different human cancers. We have previously shown that BMI-1 promotes the tumorigenicity of Ewing sarcoma family tumors (ESFTs) and that this is mediated independently of CDKN2A repression. In this study, we have discovered that high levels of BMI-1 confer resistance to contact inhibition in ESFT cells. Using stable retroviral transduction, we evaluated the consequences of BMI-1 knockdown on the growth of CDKN2A wild-type and mutant ESFT cells in subconfluent and confluent conditions. Although knockdown of BMI-1 had no effect on proliferation in low-density cultures, at high cell densities it resulted in cell cycle arrest and death. The normal cell contact inhibition response is mediated, in large part, by the recently described Hippo pathway which functions to inhibit cell proliferation and promote cell death by inactivating the Yes-Associated Protein (YAP). Significantly, we found that YAP levels, activity and expression did not diminish in confluent ESFT cells that expressed high levels of BMI-1. In contrast, YAP expression and nuclear localization were reduced in confluent BMI-1 knockdown cells suggesting that silencing of BMI-1 restored contact inhibition by restoring normal activation of the Hippo-YAP growth-suppressor pathway. Importantly, knockdown of YAP in ESFT cells resulted in profound inhibition of cell proliferation and anchorage-independent colony formation suggesting that stabilization and continued expression of YAP is critical for ESFT growth and tumorigenicity. Together, these studies reveal a previously unrecognized link between BMI-1, contact inhibition and the Hippo-YAP pathway and suggest that resistance to contact inhibition in BMI-1 overexpressing cancer cells may be in part a result of Hippo inhibition and aberrant stabilization of YAP.

Cia5d regulates a new fibroblast-like synoviocyte invasion-associated gene expression signature

Introduction

The in vitro invasive properties of rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs) have been shown to correlate with disease severity and radiographic damage. We recently determined that FLSs obtained from pristane-induced arthritis (PIA)-susceptible DA rats are also highly invasive in the same in vitro assay through Matrigel. The transfer of alleles derived from the arthritis-resistant F344 strain at the arthritis severity locus Cia5d (RNO10), as in DA.F344(Cia5d) congenics, was enough to significantly and specifically reduce the invasive properties of FLSs. This genetically controlled difference in FLS invasion involves increased production of soluble membrane-type 1 matrix metalloproteinase (MMP) by DA, and is dependent on increased activation of MMP-2. In the present study we aimed to characterize the pattern of gene expression that correlates with differences in invasion in order to identify pathways regulated by the Cia5d locus.

Methods

Synovial tissues were collected from DA and DA.F344(Cia5d) rats 21 days after the induction of PIA. Tissues were digested and FLSs isolated. After a minimum of four passages, FLSs were plated on Matrigel-covered dishes at similar densities, followed by RNA extraction. Illumina RatRef-12 expression BeadChip arrays were used. Expression data were normalized, followed by t-test, logistic regression, and cluster analysis. Real-time PCR was used to validate the microarray data.

Results

Out of the 22,523 RefSeq gene probes present in the array, 7,665 genes were expressed by the FLSs. The expression of 66 genes was significantly different between the DA and DA.F344(Cia5d) FLSs (P < 0.01). Nineteen of the 66 differentially expressed genes (28.7%) are involved in the regulation of cell cycle progression or cancer-associated phenotypes, such as invasion and contact inhibition. These included Cxcl10, Vil2 and Nras, three genes that are upregulated in DA and known to regulate MMP-2 expression and activation. Nine of the 66 genes (13.6%) are involved in the regulation of estrogen receptor signaling or transcription. Five candidate genes located within the Cia5d interval were also differentially expressed.

Conclusions

We have identified a novel FLS invasion associated gene expression signature that is regulated by Cia5d. Many of the genes found to be differentially expressed were previously implicated in cancer cell phenotypes, including invasion. This suggests a parallel in the behavior of arthritis FLSs and cancer cells, and identifies novel pathways and genes for therapeutic intervention and prognostication.

The effect of dibutyryl camp (dBcAMP) on morphological differentiation, growth and invasion in vitro of a hamster brain-tumor cell line: a comparative study of dBcAMP effects in 2- and 3-dimensional cultures

The use of agents that stimulate cancer cells to differentiate is proposed as a potential approach to the treatment of malignancy. To evaluate the effects of a differentiation inducer on morphology, growth and invasion in vitro of brain-tumor cells, a diffusely invasive hamster glial cell line (CxT3C15) was treated with ImM dibutyryl cyclic adenosine monophosphate (dBcAMP). The efficacy of dBcAMP was tested in monolayer cultures, 3-dimensional static cultures (i.e., spheroids) and confrontation cultures with an embryonic chick heart. CxT3C15 cells exhibited increased numbers of long cellular processes (morphological differentiation) following treatment of monolayer cultures with ImM dBcAMP. One mM dBcAMP also altered the macroscopic and ultrastructural morphology of CxT3C15 grown as spheroids. These alterations were: (i) a fast transition of rough to smooth morphology macroscopically, and (ii) fading of the cell borders concomitant with the disappearance of cell-membrane excrescences, as seen by scanning electron microscopy. Exponential growth of CxT3C15 in monolayers was not changed following treatment with ImM dBcAMP. Treatment of CxT3C15 spheroids with the same dose of dBcAMP caused a reduction of relative volume increase (30-40%). Invasion of CxT3C15 in an embryonic chick heart in vitro was not altered after addition (prior to or at the time of co-culture) of ImM dBcAMP to the co-cultures. These results indicate that invasion of CxT3C15 is not necessarily linked to morphological differentiation or moderated by reduced proliferation.

Antiproliferative function of glia maturation factor beta

Recombinant human glia maturation factor beta (GMF-beta) reversibly inhibits the proliferation of neoplastic cells in culture by arresting the cells in the G0/G1 phase. This phenomenon is not target-cell specific, as neural and nonneural cells are equally inhibited. When tested simultaneously, GMF-beta suppresses the mitogenic effect of acidic fibroblasts growth factor (aFGF), but the two are synergistic in promoting the morphologic differentiation of cultured astrocytes. GMF-beta also counteracts the growth-stimulating effect of pituitary extract and cholera toxin on Schwann cells. The results underscore the regulatory role of GMF-beta and its intricate interaction with the mitogenic growth factors.

Embryonal central neuroepithelial tumors: current concepts and future challenges

While the embryonal central neuroepithelial tumors present complex conceptual and clinical problems, advances in cell type identification by special neurohistological, immunohisto- and immunocytochemical techniques have permitted discrimination of distinct cytomorphogenetic entities. These are based in part on their resemblance to the normal phases of neurocytogenesis. Four of these tumors, medulloepithelioma, desmoplastic infantile ganglioglioma, pineoblastoma and medulloblastoma, are designated as multipotential in light of their capacity to undergo divergent differentiation. Cytomorphogenetic, clinical and experimental data implicate fetal neural cell targets for transformation and raise the possibility that aberrant developmental regulatory mechanisms may contribute to the biologic behavior of these tumors. Growth factors and some neuroregulatory neurotransmitters (such as serotonin) are known to act as modulators of normal neuromorphogenesis. They could play a regulatory role in central neuroepithelial tumors on the hypothesis that the aberrant behavior of the embryonal neoplasms could either be modified by functional receptor responses or result from abnormal receptor responses to these substances. Future challenges include the definition of new cytomorphogenetic entities and subgroups of the currently defined forms of embryonal CNS tumors based on the presence of specific growth factors and neuroregulatory neurotransmitters, or their receptors, the characterization of neoplastic receptor responses mediating any modulatory role of the presently known growth factors or neuroregulatory neurotransmitters on the growth and maturation potential of the embryonal central neuroepithelial tumors and the further definition of developmental, stage-specific modulators that might be operative in these tumors.

Cell and tissue culture of the central nervous system: recent developments and current applications

A survey of methods for cell and tissue culture of the central nervous system (CNS) is given. This includes a brief historical outline and description of methods in current use. Recent methodological improvements are emphasized, and it is shown how these are applied in modern neurobiological research. Both monolayer cell cultures and three-dimensional organ culture systems are widely used, each having advantages and limitations. In recent years, there has been considerable improvement of culture for prolonged periods in chemically defined media. Brain tissue from a wide spectrum of species have been used, including different types of human brain cells which can be propagated for several months. At present, these culture systems are employed for dynamic studies of the developing, the adult and ageing brain. It is possible to select neurons and the different classes of glial cells for culture purposes. Cell culture of the CNS has given new insights into the biology of brain tumours. Culture systems for experimental tumour therapy in vitro are also available. Recently, it has been shown that organ cultures of brain tissue can be used as targets for invasive glioma cells, enabling a direct study of the interactions between tumour cells and normal tissue to take place.

Glia maturation factor influences recovery from injury in neonatal rat brains

Newborn rats were injured with a puncture wound in one cerebral hemisphere. Experimental animals were treated with three i.p. injections of Glia Maturation Factor (GMF) at daily intervals starting from the time of injury, whereas control littermates were treated with equivalent amounts of bovine serum albumin. At 25 days old the size of the cerebral cortex at the plane of injury was measured on representative brain sections. In control rats the injured side was 18% smaller than the normal side whereas in GMF-treated animals the difference was only 1%. The results suggest a possible regulatory role of GMF in promoting tissue recovery from brain damage.

Invasiveness of primary brain tumors

Primary malignant neoplasms of the nervous system differ from other types of malignancy in several ways. Clinical progression is due to local invasive growth, while metastases outside the skull are rare. The tumors show no sharp delimitation from the surrounding normal tissue. At the edge, an ill-defined area of invasive tumor cells, reacting glial cells and inflammatory cells is present. At the same time the primary brain tumors are biologically heterogeneous. In this review, a short survey of markers for malignancy in primary brain tumors is given, and some properties of importance for invasive behavior, are listed. These include different cellular enzymes, phagocytotic property, locomotive and proliferative characteristics. Studies of primary brain tumors in situ show invasive growth into the surrounding brain tissue, often followed by hemorrhage and necrosis. In addition spread of tumor cells takes place along preexisting intracranial structures. Recently, several systems for the study of brain tumor invasiveness in culture have been elaborated. Both experimental and human gliomas have been tested. The target tissues include organ culture of embryonic chick heart muscle, chorioallantoic membrane, fetal rat brain tissue and reconstructed vessel walls. It has been shown that glioma cells are able to split junctions between normal cells. They destroy and phagocytose the normal cells and penetrate the normal tissue. The use of brain tissue and reaggregated brain cell cultures as target for glioma cells in culture opens the possibility for an elucidation of invasiveness as one of the most important properties of malignancy in the nervous system.

Specific chromosome changes associated with viral transformation of rat glial cells

Karyotypes of three malignant cell lines derived from Wistar and WKA/Mk fetal rat glioblasts, transformed by murine sarcoma virus (MSV-M-os) as well as those of four cell lines derived from C6 glioma cells of Wistar origin, retransformed by MSV-M-os, were analyzed in early culture passages. The C6 line had a modal number of 42 chromosomes with a normal male karyotype, and only a minor population of cells with 43 chromosomes. The modal chromosome number in every transformed glial cell line shifted from 42 to 43. The G-banding pattern revealed consistent chromosome abnormalities. Structural chromosome changes occurred in one chromosome No. 2 (2q-) and in one No. 4 (4q+). The cells with a 43 chromosome karyotype showed trisomy of chromosome No. 12 and its heteromorphism, a finding also confirmed by silver staining. Identical chromosome changes were found in transformed C6 cell lines. A further interesting feature was that all malignant cells had different distribution patterns of silver-stained nucleolar organizer regions (Ag-NORs) among particular chromosomes (Nos. 3, 11 and 12) from normal cells, showing an increased frequency of chromosome No. 12 with Ag-NORs. These results suggested that the gain and/or loss of specific segments involved in chromosomes Nos. 2, 4 and 12 contain(s) genes favorable to malignant transformation in rat glial cells.