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Query: HUMANGGP:010955 (
mda-7
)
464
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Cultured human melanoma cells lose proliferative capacity and terminally differentiate after treatment with the combination of recombinant human fibroblast interferon (
IFN-beta
) and mezerein (MEZ). Subtraction hybridization of cDNA libraries prepared from actively proliferating human H0-1 melanoma cells from cDNA libraries produced from H0-1 cells treated with
IFN-beta
+ MEZ identifies a novel melanoma differentiation-associated (mda) cDNA,
mda-7
, that displays elevated expression in differentiation inducer-treated H0-1 cells.
mda-7
encodes a novel protein of 206 amino acids with a predicted size of 23.8 kDa. The level of
mda-7
mRNA is elevated in actively proliferating normal human melanocytes versus primary and metastatic human melanomas. In the Matrigel-assisted melanoma progression model,
mda-7
expression decreases in early vertical growth phase primary human melanoma cells selected for autonomous or enhanced tumor formation in nude mice. Treatment of human melanomas with
IFN-beta
+ MEZ, and to a lesser extent with MEZ, results in growth suppression and induced or enhanced
mda-7
expression. Immunoprecipitation analyses using peptide-derived rabbit polyclonal antibodies detect increases in
mda-7
protein, and a higher molecular weight protein of approximately 90 to 100 kDa, in MEZ and
IFN-beta
+ MEZ treated H0-1 cells.
mda-7
is a highly conserved gene with an homologous sequence in the genome of yeast. Transfection of
mda-7
expression constructs into H0-1 and C8161 human melanoma cells reduces growth and inhibits colony formation. These results confirm that
mda-7
has antiproliferative properties in human melanoma cells and in this context may contribute to terminal cell differentiation. The
mda-7
gene may also function as a negative regulator of melanoma progression.
...
PMID:Subtraction hybridization identifies a novel melanoma differentiation associated gene, mda-7, modulated during human melanoma differentiation, growth and progression. 854 4
Induction of irreversible growth arrest and terminal differentiation in human melanoma cells following treatment with recombinant human fibroblast interferon (
IFN-beta
) and mezerein (MEZ) results in elevated expression of a specific melanoma differentiation associated gene,
mda-7
. Experiments were conducted to define the mechanism involved in the regulation of
mda-7
expression in differentiating human melanoma cells. The
mda-7
gene is actively transcribed in uninduced HO-1 human melanoma cells and the rate of transcription of
mda-7
is not significantly enhanced by treatment with
IFN-beta
, MEZ or IFN-beta+MEZ. The high basal activity of the
mda-7
promoter in uninduced melanoma cells and the absence of enhancing effect upon treatment with differentiation inducers is corroborated by transfection studies using the promoter region of
mda-7
linked to a luciferase reporter gene containing the SV40 polyadenylation signal sequence. RT - PCR analysis detects the presence of low levels of
mda-7
transcripts in uninduced and concomitant increases in differentiation inducer treated HO-1 cells. However, steady-state
mda-7
mRNA is detected only in IFN-beta+MEZ and to a lesser degree in MEZ treated cells. We show that induction of terminal differentiation of HO-1 cells with IFN-beta+MEZ dramatically increases the half-life of
mda-7
mRNA while treatment with cycloheximide results in detectable
mda-7
mRNA in control and inducer treated cells. These observations confirm constitutive activity of the
mda-7
promoter in HO-1 cells irrespective of differentiation status suggesting posttranscriptional processes as important determinants of
mda-7
expression during terminal differentiation. The 3' UTR region of
mda-7
contains AU-rich elements (ARE) that contribute to rapid
mda-7
mRNA turnover during proliferation and reversible differentiation, a process controlled by a labile protein factor(s). Substitution of the SV40 polyadenylation signal sequence in the luciferase reporter plasmid with the
mda-7
-ARE-3'-UTR renders the Luciferase message unstable when expressed in proliferating and reversibly differentiated melanoma cells. In contrast, the luciferase message is stabilized when the
mda-7
-ARE-3'-UTR construct is expressed in terminally differentiated HO-1 cells. These results provide compelling evidence that
mda-7
expression during terminal differentiation in human melanoma cells is regulated predominantly at a posttranscriptional level.
...
PMID:Regulation of mda-7 gene expression during human melanoma differentiation. 1071 78
Treatment of human melanoma cells with a combination of recombinant fibroblast interferon (
IFN-beta
) and the protein kinase C (PKC) activator mezerein (MEZ) causes a rapid and irreversible suppression in growth and terminal cell differentiation. Temporal subtraction hybridization combined with random clone selection, reverse Northern hybridization, high throughput microchip cDNA array screening, and serial cDNA library arrays permit the identification and cloning of genes that are differentially expressed during proliferative arrest and terminal differentiation in human melanoma cells. A specific melanoma differentiation associated (mda) gene,
mda-7
, exhibits reduced expression as a function of melanoma progression from melanocyte to metastatic melanoma. In contrast, treatment of metastatic melanoma cells with
IFN-beta
+ MEZ results in expression of
mda-7
mRNA and protein. To evaluate the mechanism underlying the differential expression of
mda-7
as a function of melanoma progression and induction of growth arrest and differentiation in human melanoma cells the promoter region of this gene has been isolated from a human placental genomic library and characterized. Sequence analysis by GCG identifies multiple recognition sites for the AP-1 and C/EBP transcription factors. Employing a heterologous
mda-7
luciferase gene reporter system, we demonstrate that ectopic expression of either AP-1/cJun or C/EBP can significantly enhance expression of the
mda-7
promoter in melanoma cells. In contrast, a dominant negative mutant of cJun, TAM67, is devoid of promoter-enhancing ability. Western blot analyses reveals that cJun and the C/EBP family member C/EBP-beta are physiologically relevant transcription factors whose expression corresponds with
mda-7
mRNA expression. Electrophoretic mobility shift assays (EMSA) performed using nuclear protein extracts from terminally differentiated human melanoma cells document binding to regions of the
mda-7
promoter that correspond to consensus binding sites for AP-1 and C/EBP. These results provide further mechanistic insights into the regulation of the
mda-7
gene during induction of terminal cell differentiation in human melanoma cells.
...
PMID:AP-1 and C/EBP transcription factors contribute to mda-7 gene promoter activity during human melanoma differentiation. 1094 17
Abnormalities in cellular differentiation are frequent occurrences in human cancers. Treatment of human melanoma cells with recombinant fibroblast interferon (
IFN-beta
) and the protein kinase C activator mezerein (MEZ) results in an irreversible loss in growth potential, suppression of tumorigenic properties and induction of terminal cell differentiation. Subtraction hybridization identified melanoma differentiation associated gene-7 (mda-7), as a gene induced during these physiological changes in human melanoma cells. Ectopic expression of mda-7 by means of a replication defective adenovirus results in growth suppression and induction of apoptosis in a broad spectrum of additional cancers, including melanoma, glioblastoma multiforme, osteosarcoma and carcinomas of the breast, cervix, colon, lung, nasopharynx and prostate. In contrast, no apparent harmful effects occur when mda-7 is expressed in normal epithelial or fibroblast cells. Human clones of mda-7 were isolated and its organization resolved in terms of intron/exon structure and chromosomal localization. Hu-mda-7 encompasses seven exons and six introns and encodes a protein with a predicted size of 23.8 kDa, consisting of 206 amino acids. Hu-mda-7 mRNA is stably expressed in the thymus, spleen and peripheral blood leukocytes. De novo mda-7 mRNA expression is also detected in human melanocytes and expression is inducible in cells of melanocyte/melanoma lineage and in certain normal and cancer cell types following treatment with a combination of
IFN-beta
plus MEZ. Mda-7 expression is also induced during megakaryocyte differentiation induced in human hematopoietic cells by treatment with TPA (12-O-tetradecanoyl phorbol-13-acetate). In contrast, de novo expression of mda-7 is not detected nor is it inducible by IFN-beta+MEZ in a spectrum of additional normal and cancer cells. No correlation was observed between induction of mda-7 mRNA expression and growth suppression following treatment with IFN-beta+MEZ and induction of endogenous mda-7 mRNA by combination treatment did not result in significant intracellular
MDA-7
protein. Radiation hybrid mapping assigned the mda-7 gene to human chromosome 1q, at 1q 32.2 to 1q41, an area containing a cluster of genes associated with the IL-10 family of cytokines. Mda-7 represents a differentiation, growth and apoptosis associated gene with potential utility for the gene-based therapy of diverse human cancers.
...
PMID:Genomic structure, chromosomal localization and expression profile of a novel melanoma differentiation associated (mda-7) gene with cancer specific growth suppressing and apoptosis inducing properties. 1170 29
Human melanoma cells growth arrest irreversibly, lose tumorigenic potential and terminally differentiate after treatment with a combination of fibroblast interferon (
IFN-beta
) and the protein kinase C activator mezerein (MEZ). Applying subtraction hybridization to this model differentiation system permitted cloning of melanoma differentiation associated gene-7,
mda-7
. Expression of
mda-7
inversely correlates with melanoma development and progression, with elevated expression in normal melanocytes and nevi and increasingly reduced expression in radial growth phase, vertical growth phase and metastatic melanoma. When expressed by means of a replication incompetent adenovirus (Ad.
mda-7
) growth of melanoma, but not normal early passage or immortal human melanocytes, is dramatically suppressed and cells undergo programmed cell death (apoptosis). Infection of metastatic melanoma cells with Ad.
mda-7
results in an increase in cells in the G(2)/M phase of the cell cycle and changes in the ratio of pro-apoptotic (BAX, BAK) to anti-apoptotic (BCL-2, BCL-XL) proteins. Ad.
mda-7
infection results in a temporal increase in
mda-7
mRNA and intracellular
MDA-7
protein in most of the melanocyte/melanoma cell lines and secretion of
MDA-7
protein is readily detected following Ad.
mda-7
infection of both melanocytes and melanoma cells. The present studies document a differential response of melanocytes versus melanoma cells to ectopic expression of
mda-7
and support future applications of
mda-7
for the gene-based therapy of metastatic melanoma.
...
PMID:The cancer growth suppressing gene mda-7 induces apoptosis selectively in human melanoma cells. 1185 Jul 99
Restoration of the tumor-suppression function by gene transfer of the melanoma differentiation-associated gene 7 (MDA7)/
interleukin 24
(
IL-24
) successfully induces apoptosis in melanoma tumors in vivo. To address the molecular mechanisms involved, we previously revealed that MDA7/
IL-24
treatment of melanoma cells down-regulates interferon regulatory factor (IRF)-1 expression and concomitantly up-regulates IRF-2 expression, which competes with the activity of IRF-1 and reverses the induction of IRF-1-regulated inducible nitric oxide synthase (iNOS). Interferons (IFNs) influence melanoma cell survival by modulating apoptosis. A class I IFN (IFN-alpha) has been approved for the treatment of advanced melanoma with some limited success. A class II IFN (IFN-gamma), on the other hand, supports melanoma cell survival, possibly through constitutive activation of iNOS expression. We therefore conducted this study to explore the molecular pathways of MDA7/
IL-24
regulation of apoptosis via the intracellular induction of IFNs in melanoma. We hypothesized that the restoration of the MDA7/
IL-24
axis leads to upregulation of class I IFNs and induction of the apoptotic cascade. We found that MDA7/
IL-24
induces the secretion of endogenous
IFN-beta
, another class I IFN, leading to the arrest of melanoma cell growth and apoptosis. We also identified a series of apoptotic markers that play a role in this pathway, including the regulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas-FasL. In summary, we described a novel pathway of MDA7/
IL-24
regulation of apoptosis in melanoma tumors via endogenous
IFN-beta
induction followed by IRF regulation and TRAIL/FasL system activation.
...
PMID:Killing of human melanoma cells induced by activation of class I interferon-regulated signaling pathways via MDA-7/IL-24. 1851 Dec 92
