Increased invasive capacity of connexin43-overexpressing malignant glioma cells

2003 ◽  
Vol 99 (6) ◽  
pp. 1039-1046 ◽  
Author(s):  
Wei Zhang ◽  
Chiedozie Nwagwu ◽  
Duc Minh Le ◽  
V. Wee Yong ◽  
Hua Song ◽  
...  
Keyword(s):  
Malignant Glioma ◽  
Gap Junction ◽  
Cell Invasion ◽  
Malignant Gliomas ◽  
Glioma Cells ◽  
C6 Glioma Cells ◽  
Glioma Invasion ◽  
Content Type ◽  
Malignant Glioma Cells ◽  
Fine Print

Object. Malignant glioma cells, similar to astrocytes, express connexin43 (Cx43) universally but at widely varied levels. Data from previous studies have demonstrated that malignant glioma cells form functional gap junction channels among themselves as well as with astrocytes and that such a communication has the potential to modulate the phenotypic characteristics of astrocytes. Recently, gap junctions have been demonstrated to play a role in the invasive phenotype of malignant gliomas. In this study, the authors have further investigated the motility and invasion ability of Cx43-overexpressing and Cx43-deficient malignant glioma cells. Methods. Using a standard invasion system of a Matrigel transwell invasion chamber, the authors found that the number of Cx43-transfected C6 glioma cells (C6-Cx43 cells) migrating through the Matrigel-coated membrane was similar to that of mock-transfected control cells (C6-mock cells) during the first 24 hours, but increased significantly thereafter. When these cells were cocultured with astrocytes, the number of invading C6-Cx43 cells was more than threefold greater than the number of invading C6-mock cells. Results of an in vitro cell motility assay also demonstrated that C6-Cx43 cells were more motile and scatter-active than C6-mock cells. Furthermore, zymographic analysis of MMPs, an important determinant in glioma invasion, demonstrated that the amounts of MMP-2 and MMP-9 in culture medium collected from C6-Cx43 cells were orders of magnitude higher than those from C6-mock cells. In addition, BB-94, a synthetic MMP inhibitor, significantly inhibited C6-Cx43 cell invasion. Conclusions. The overexpression of gap junction proteins in glioma cells and the intercellular communication between tumor and nontumor glia cells may play important roles in the facilitation of glioma cell invasion.

Communication between malignant glioma cells and vascular endothelial cells through gap junctions

2003 ◽  
Vol 98 (4) ◽  
pp. 846-853 ◽  
Author(s):  
Wei Zhang ◽  
Joseph A. DeMattia ◽  
Hua Song ◽  
William T. Couldwell
Keyword(s):  
Malignant Glioma ◽  
Gap Junction ◽  
Vascular Endothelial Cells ◽  
Glioma Cells ◽  
Tube Formation ◽  
Vascular Endothelial ◽  
Content Type ◽  
Human Malignant Glioma ◽  
Malignant Glioma Cells ◽  
Fine Print

Object. Extensive invasion and angiogenesis are hallmark features of malignant gliomas. Communication between malignant glioma cells and surrounding astrocytes occurs, resulting in transformation of the astrocytic phenotype. In the present study, the authors examined whether malignant glioma cells and vascular endothelial cells (VECs) communicate through the formation of gap junctions and whether this communication influences angiogenesis. Methods. Connexin43 (Cx43), a gap junction protein expressed in glioma cells, was identified in human umbilical VECs (HUVECs). Immunocytochemical staining for Cx43 demonstrated immunoreactive plaques at areas of cell—cell contact among HUVECs as well as between HUVECs and Cx43-expressing malignant glioma cells. Dye transfer, performed using the gap junction—permeable dye dicarboxy-dichlorofluorescein diacetate (CDCF), among these cocultures indicated that these were functional communications. Calcium signaling also occurred from malignant glioma cells to HUVECs. Tube formation by HUVECs cocultured with Cx43-transfected T98G malignant glioma cells (T98G-Cx43 cells) or with U87MG malignant glioma cells, which naturally express Cx43, was significantly increased compared with tube formation by HUVECs alone. The difference in tube formation by HUVECs cocultured with empty vector—transfected T98G glioma cells (T98G-mock cells) or with Cx43-deficient U373MG malignant glioma cells and tube formation by HUVECs alone was not statistically significant. Furthermore, the concentration of vascular endothelial growth factor (VEGF), an angiogenic factor important for the induction of angiogenesis and blood vessel formation, was significantly higher in medium harvested from cultures of T98G-Cx43 cells than in that harvested from cultures of control T98G-mock cells. Human malignant glioma U87MG cells also secreted increased concentrations of VEGF as compared with HUVECs alone. Nevertheless, there was no statistically significant difference in tube formation by HUVECs cultured in medium conditioned by either Cx43-expressing or Cx43-deficient glioma cells, suggesting that the direct gap junction communication between glioma cells and HUVECs may play a much more significant role than the increased VEGF secretion in vascular tube formation in this assay. Conclusions. These results indicate that functional gap junction formation between human malignant glioma cells and VECs occurs. This communication appears to influence tumor angiogenesis. Targeting gap junction signaling may offer a potential mechanism for therapy in patients with these tumors.

Resistance to growth inhibition by transforming growth factor—β in malignant glioma cells with functional receptors

1998 ◽  
Vol 88 (3) ◽  
pp. 529-534 ◽  
Author(s):  
Shiro Isoe ◽  
Hirofumi Naganuma ◽  
Shin Nakano ◽  
Atsushi Sasaki ◽  
Eiji Satoh ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Malignant Glioma ◽  
Cell Lines ◽  
Glioma Cell ◽  
Glioma Cells ◽  
Content Type ◽  
Glioma Cell Lines ◽  
Malignant Glioma Cells ◽  
Tgf Β1 ◽  
Fine Print

Object. The aim of this study was to investigate the mechanism by which malignant glioma cells escape from growth inhibition mediated by transforming growth factor-β (TGF-β), a ubiquitous cytokine that inhibits cell proliferation by causing growth arrest in the G1 phase of the cell cycle. Methods. The authors measured the response of eight malignant glioma cell lines to the growth-inhibiting activity of TGF-β in vitro and the expression of TGF-β Types I and II receptors in malignant glioma cells. The effect of TGF-β on the expression of a p27Kip1 cyclin-dependent kinase inhibitor was also investigated to assess the downstream signal transmission from TGF-β receptors. All malignant glioma cell lines were insensitive to growth inhibition by TGF-β1 and TGF-β2. Analyses of TGF-β receptors by means of affinity labeling in which 125I-TGF-β1 was used showed that six glioma lines had both TGF-β Types I and II receptors on their cell surfaces, whereas two lines had very small amounts of TGF-β Type I and/or Type II receptors. Northern blot analysis showed that all tumor lines expressed variable levels of messenger RNAs for both TGF-β Types I and II receptors. Flow cytometric analyses revealed that treatment of malignant glioma cells with TGF-β1 significantly downregulated the expression of p27Kip1 protein in all malignant glioma cell lines except one. Conclusions. The authors suggest that most malignant glioma cells express TGF-β Types I and II receptors, which can transmit some signals downstream and that the loss of response to TGF-β growth inhibition may not be caused by an abnormality of the TGF-β receptors.

Isolation and characterization of human malignant glioma cells from histologically normal brain

1997 ◽  
Vol 86 (3) ◽  
pp. 525-531 ◽  
Author(s):  
Daniel L. Silbergeld ◽  
Michael R. Chicoine
Keyword(s):  
Malignant Glioma ◽  
Cell Lines ◽  
Growth Rates ◽  
Glioma Cells ◽  
Normal Brain ◽  
Content Type ◽  
Human Malignant Glioma ◽  
Malignant Glioma Cells ◽  
Fine Print ◽  
Neuropathological Evaluation

✓ Brain invasion prevents complete surgical extirpation of malignant gliomas; however, invasive cells from distant, histologically normal brain previously have not been isolated, cultured, and characterized. To evaluate invasive human malignant glioma cells, the authors established cultures from gross tumor and histologically normal brain. Three men and one woman, with a mean age of 67 years, underwent two frontal and two temporal lobectomies for tumors, which yielded specimens of both gross tumor and histologically normal brain. Each specimen was acquired a minimum of 4 cm from the gross tumor. The specimens were split: a portion was sent for neuropathological evaluation (three glioblastomas multiforme and one oligodendroglioma) and a portion was used to establish cell lines. Morphologically, the specimens of gross tumor and histologically normal brain were identical in three of the four cell culture pairs. Histochemical staining characteristics were consistent both within each pair and when compared with the specimens sent for neuropathological evaluation. Cultures demonstrated anchorage-independent growth in soft agarose and neoplastic karyotypes. Growth rates in culture were greater for histologically normal brain than for gross tumor in three of the four culture pairs. Although the observed increases in growth rates of histologically normal brain cultures do not correlate with in vivo behavior, these findings corroborate the previously reported stem cell potential of invasive glioma cells. Using the radial dish assay, no significant differences in motility between cultures of gross tumor and histologically normal brain were found. In summary, tumor cells were cultured from histologically normal brain acquired from a distance greater than 4 cm from the gross tumor, indicating the relative insensitivity of standard histopathological identification of invasive glioma cells (and hence the inadequacy of frozen-section evaluation of resection margins). Cell lines derived from gross tumor and histologically normal brain were usually histologically identical and demonstrated equivalent motility, but had different growth rates.

Enhanced radiosensitivity of malignant glioma cells after adenoviral p53 transduction

1999 ◽  
Vol 91 (6) ◽  
pp. 997-1004 ◽  
Author(s):  
William C. Broaddus ◽  
Yue Liu ◽  
Laura L. Steele ◽  
George T. Gillies ◽  
Peck-Sun Lin ◽  
...  
Keyword(s):  
Malignant Glioma ◽  
Glioma Cells ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Wild Type ◽  
Content Type ◽  
Cranial Radiation ◽  
Adenoviral Transduction ◽  
Wild Type P53 ◽  
Malignant Glioma Cells ◽  
Fine Print

Object. The goal of this study was to determine whether adenoviral vector—mediated expression of human wildtype p53 can enhance the radiosensitivity of malignant glioma cells that express native wild-type p53.The p53 gene is thought to function abnormally in the majority of malignant gliomas, although it has been demonstrated to be mutated in only approximately 30%. This has led to studies in which adenoviral transduction with wild-type human p53 has been investigated in an attempt to slow tumor cell growth. Recent studies suggest that reconstitution of wild-type p53 can render cells more susceptible to radiation-mediated death, primarily by p53-mediated apoptosis.Methods. Rat RT2 glioma cells were analyzed for native p53 status by reverse transcriptase—polymerase chain reaction and sequence analysis and for p53 expression by Western blot analysis. Clonogenic survival and the terminal deoxynucleotidyl transferase—mediated deoxyuridine triphosphate nick-end labeling assay were used to characterize RT2 cell radiosensitivity and apoptosis, respectively, with and without prior transduction with p53-containing and control adenoviral vectors. Animal survival length was monitored after intracerebral implantation with transduced and nontransduced RT2 cells, with and without cranial radiation.The RT2 cells were demonstrated to express native rat wild-type p53 and to markedly overexpress human p53 following adenoviral p53 transduction. The combination of p53 transduction followed by radiation resulted in marked decreases in RT2 cell survival and increases in apoptosis at radiation doses from 2 to 6 Gy. Animals receiving cranial radiation after intracerebral implantation with RT2 cells previously transduced with p53 survived significantly longer than control animals (p < 0.01).Conclusions. The ability to enhance the radiosensitivity of malignant glioma cells that express wild-type p53 by using adenoviral transduction to induce overexpression of p53 offers hope for this approach as a therapeutic strategy, not only in human gliomas that express mutant p53, but also in those that express wild-type p53.

Motility factor produced by malignant glioma cells: role in tumor invasion

1990 ◽  
Vol 73 (6) ◽  
pp. 881-888 ◽  
Author(s):  
Takanori Ohnishi ◽  
Norio Arita ◽  
Toru Hayakawa ◽  
Shuichi Izumoto ◽  
Takuyu Taki ◽  
...  
Keyword(s):  
Cell Migration ◽  
Malignant Glioma ◽  
Tumor Invasion ◽  
Cytochalasin B ◽  
Glioma Cells ◽  
Actin Microfilaments ◽  
Content Type ◽  
Motility Factor ◽  
Malignant Glioma Cells ◽  
Fine Print

✓ To better understand the cellular mechanism of tumor invasion, the production of a cell motility-stimulating factor by malignant glioma cells was studied in vitro. Serum-free conditioned media from cultures of rat C6 and human T98G cell lines contained a factor that stimulated the locomotion of the producer cells. This factor was termed the “glioma-derived motility factor.” The glioma-derived motility factor is a heat-labile protein with a molecular weight greater than 10 kD and has relative stability to acid. The factor showed not only chemotactic activity but also chemokinetic (stimulated random locomotion) activity in the two types of glioma cells studied. Although glioma-derived motility factors in conditioned media obtained from two different cell origins are likely to be the same, chemokinetic migration of T98G cells to their conditioned medium was much stronger than that of C6 cells to theirs. Coincubation of cells with cytochalasin B, which disrupts the assembly of cellular actin microfilaments, almost completely inhibited the cell migration stimulated by glioma-derived motility factor. Cytochalasin B also induced marked alterations in cell morphology, including cell retraction and arborization, while the drug did not affect cell attachment to culture dishes. These results indicate that glioma cells produce a motility factor which may play a role particularly when tumor cells are detached and migrate away from the original tumor mass, thus promoting tumor invasion. Also, glioma cell migration stimulated by the motility factor requires the normal organization of cytoskeletons such as actin microfilaments.

Administration of interleukin-12 and -18 enhancing the antitumor immunity of genetically modified dendritic cells that had been pulsed with Semliki Forest virus—mediated tumor complementary DNA

2002 ◽  
Vol 97 (5) ◽  
pp. 1184-1190 ◽  
Author(s):  
Ryuya Yamanaka ◽  
Naoki Yajima ◽  
Naoto Tsuchiya ◽  
Junpei Honma ◽  
Ryuichi Tanaka ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Antitumor Immunity ◽  
Semliki Forest Virus ◽  
Malignant Gliomas ◽  
Glioma Cells ◽  
Antitumor Effects ◽  
Content Type ◽  
Immunogene Therapy ◽  
Fine Print

Object. Immunogene therapy for malignant gliomas was further investigated in this study to improve its therapeutic efficacy. Methods. Dendritic cells (DCs) were isolated from bone marrow and pulsed with phosphate-buffered saline or Semliki Forest virus (SFV)—mediated 203 glioma complementary (c)DNA with or without systemic administration of interleukin (IL)-12 and IL-18 to treat mice bearing the 203 glioma. To study the immune mechanisms involved in tumor regression, the authors investigated tumor growth of an implanted 203 glioma model in T cell subset—depleted mice and in interferon (IFN) γ—neutralized mice. To examine the protective immunity produced by tumor inoculation, a repeated challenge of 203 glioma cells was given by injecting the cells into the left thighs of surviving mice and the growth of these cells was monitored. The authors demonstrated that the combined administration of SFV-cDNA, IL-12, and IL-18 produced significant antitumor effects against the growth of murine glioma cells in vivo and also can induce specific antitumor immunity. The synergic effects of the combination of SFV-cDNA, IL-12, and IL-18 in vivo were also observed to coincide with markedly augmented IFNγ production. The antitumor effects of this combined therapy are mediated by CD4+ and CD8+ T cells and by NK cells. These results indicate that the use of IL-18 and IL-12 in DC-based immunotherapy for malignant glioma is beneficial. Conclusions. Immunogene therapy combined with DC therapy, IL-12, and IL-18 may be an excellent candidate in the development of a new treatment protocol. The self-replicating SFV system may therefore provide a novel approach for the treatment of malignant gliomas.

Growth inhibition of human malignant glioma cells induced by the PI3-K—specific inhibitor

2003 ◽  
Vol 98 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Takashi Shingu ◽  
Kazuo Yamada ◽  
Nobumasa Hara ◽  
Kouzo Moritake ◽  
Harumi Osago ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Malignant Glioma ◽  
Cell Lines ◽  
Akt Pathway ◽  
Content Type ◽  
Phosphorylated Akt ◽  
Human Malignant Glioma ◽  
The Status ◽  
Malignant Glioma Cells ◽  
Fine Print

Object. The phosphatase and tensin homolog deleted from chromosome 10 (PTEN) functions as a tumor suppressor by negatively regulating the growth/survival signals of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. The PI3-K/Akt pathway in PTEN-deficient tumors may be one of the key targets for anticancer therapy. The authors examined the effects of the PI3-K inhibitor 2-(4-morpholinyl)-8-phenylchromone (LY294002) on human malignant glioma cells, and compared these effects on PTEN-deficient cells with those on PTEN—wild-type (PTEN-wt) cells. Methods. Using human malignant glioma cell lines, including the PTEN-deficient cells A172 and U87MG and the PTEN-wt cells LN18 and LN229, the effects of LY294002 on cell growth, apoptosis, and chemotherapeutic agent—induced cytotoxicity were evaluated. The LY294002 inhibited the growth of U87MG cells associated with reduced phosphatidylinositol 3,4,5,-trisphosphate and phosphorylated Akt, and also induced growth inhibition in three other cell lines. Although LY294002 caused apoptosis in all four cell lines, apoptosis seemed to contribute to only a small portion of growth inhibition induced by LY294002. There was no link between the status of PTEN and the median inhibitory concentration values for LY294002 or between the gene status and the extent of LY294002-induced apoptosis. The LY294002 significantly augmented the cytotoxicity induced by etoposide in PTEN-deficient cells, but not in PTEN-wt cells. Enhancement of 1,3-bis(2-chloroethyl)-1-nitrosourea— and cisplatin-induced cytotoxicity by LY294002 was not linked to the status of PTEN. No marked difference in the amounts of phosphorylated Akt was found between PTEN-deficient and PTEN-wt cells. Conclusions. The findings show that PI3-K is a possible target for therapy in patients with gliomas, and PI3-K inhibitors in combination with chemotherapeutic agents could be potent therapeutic modalities for patients with malignant gliomas.

Targeting adenovirus to CD80 and CD86 receptors increases gene transfer efficiency to malignant glioma cells

2007 ◽  
Vol 107 (3) ◽  
pp. 617-627 ◽  
Author(s):  
Ilya V. Ulasov ◽  
Angel A. Rivera ◽  
Yu Han ◽  
David T. Curiel ◽  
Zeng B. Zhu ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Brain Tumors ◽  
Malignant Glioma ◽  
Malignant Gliomas ◽  
Glioma Cells ◽  
Luciferase Reporter ◽  
Transduction Efficiency ◽  
Wild Type ◽  
Malignant Glioma Cells

Object Gene therapy protocols for malignant gliomas utilize adenoviral vectors that rely almost exclusively on the adenovirus serotype 5 (Ad5) backbone. The authors have previously shown that chimeric vectors that bind to the Ad3 receptor, or CD46, increase the transduction efficiency of malignant brain tumors. In light of the debate regarding the efficacy of CD46 compared with CD80/CD86 in binding Ad3 virions, the authors now examine the expression and transduction efficiency of Ad5/3 chimeras that bind via CD80/CD86. Methods The authors first analyzed CD80/CD86 expression in glioma cell lines. They then used three replication-defective vectors containing a luciferase reporter gene: Ad5/3 (containing the tail and shaft domain of Ad5 and the knob domain of Ad3); Ad3/5 (containing the tail of Ad5, shaft of Ad3, and knob of Ad5); and Ad3/3 (containing the tail of Ad5, shaft of Ad3, and knob of Ad3). These vectors were analyzed both in vitro and in vivo against malignant glioma cells. To examine further the effect of Ad5/3 fiber modification, the authors created an oncolytic vector, conditionally replicative Ad5/3 (CRAd5/3). Results The Ad5/3 vector showed a 10- to 100-fold enhanced transduction efficiency of malignant glioma compared with replication-defective wild-type adenovirus (reAd5) (p < 0.05). Moreover the use of Ad5/3 reduced transgene expression by more than 90% in normal human brain cells compared with reAd5. Finally, the use of CRAd5/3 inhibited tumor cell proliferation by 43% more than replication-competent wild-type virus in vitro (p < 0.05). Conclusions The results of this study demonstrate that the Ad5/3 vector offers superior transduction efficiency and low toxicity in the setting of brain tumors, and therefore represents a potential new approach to gene therapy for malignant gliomas.

Reduced tumorigenicity of rat glioma cells in the brain when mediated by hygromycin phosphotransferase

2001 ◽  
Vol 94 (4) ◽  
pp. 596-604 ◽  
Author(s):  
Adília Hormigo ◽  
David R. Friedlander ◽  
Perry A. Brittis ◽  
David Zagzag ◽  
Martin Grumet
Keyword(s):  
Cell Proliferation ◽  
Rat Brain ◽  
Glioma Cells ◽  
C6 Glioma ◽  
C6 Glioma Cells ◽  
C6 Cells ◽  
Content Type ◽  
Hygromycin Phosphotransferase ◽  
The Brain ◽  
Fine Print

Object. A variant of C6 glioma cells, C6R-G/H cells express hygromycin phosphotransferase (HPT) and appear to have reduced tumorigenicity in the embryonic brain. The goal of this study was to investigate their reduced capacity to generate tumors in the adult rat brain. Methods. Cell lines were implanted into rat brains and tumorigenesis was evaluated. After 3 weeks, all rats with C6 cells showed signs of neurological disease, whereas rats with C6R-G/H cells did not and were either killed then or allowed to survive until later. Histological studies were performed to analyze tumor size, malignancy, angiogenesis, and cell proliferation. Cells isolated from rat brain tumors were analyzed for mutation to HPT by testing their sensitivity to hygromycin. Conclusions. The results indicate that HPT suppresses tumor formation. Three weeks after implantation, only 44% of animals implanted with C6R-G/H cells developed tumors, whereas all animals that received C6 glioma cells developed high-grade gliomas. The C6R-G/H cells filled a 20-fold smaller maximal cross-sectional area than the C6 cells, and exhibited less malignant characteristics, including reduced angiogenesis, mitosis, and cell proliferation. Similar results were obtained in the brain of nude rats, indicating that the immune system did not play a significant role in suppressing tumor growth. The combination of green fluorescent protein (GFP) and HPT was more effective in suppressing tumorigenesis than either plasmid by itself, indicating that the GFP may protect against inactivation of the HPT. Interestingly, hygromycin resistance was lost in tumor cells that were recovered from a group of animals in which C6R-G/H cells formed tumors, confirming the correlation of HPT with reduced tumorigenicity.

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