The cancer growth suppressing gene mda-7 induces apoptosis selectively in human melanoma cells

Abstract

Human melanoma cells growth arrest irreversibly, lose tumorigenic potential and terminally di erentiate after treatment with a combination of ®broblast interferon (IFN-b) and the protein kinase C activator mezerein (MEZ). Applying subtraction hybridization to this model di erentiation system permitted cloning of melanoma di erentiation 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 di erential response of melanocytes versus melanoma cells to ectopic expression of mda-7 and support future applications of mda-7 for the genebased therapy of metastatic melanoma.

Conservation of the genomic structure and receptor-mediated signaling between human and rat IL-24

“…9 Ectopic expression of MDA-7 using a replication-incompetent adenovirus construct (Ad.MDA-7) induced growth suppression and apoptosis in a number of human melanoma cell lines without the induction of terminal differentiation. 16 Similar effects also have been observed in a variety of other human cancer derived cell lines, including glioblastoma multiform, osteosarcoma, and breast, cervix, colon, lung, nasopharynx and prostate carcinomas, but not in any normal cells. 17,18 However, most of these studies were conducted before MDA-7 was shown to be a secreted cytokine, and the antitumor effect described in these studies was thought to result from intracellular, rather than secreted MDA-7.…”

Combinatorial synergy induced by adenoviral-mediated mda-7 and Herceptin in Her-2+ breast cancer cells

“…Differences in tumor size were analyzed for significance by the Student's t-test. Enhanced in vitro growth inhibitory and cytotoxic activity of Ad-mda7 and Herceptin in Her-2 þ breast cancer cells The antiproliferative effects of Ad-mda7 in various cancer cell types have been demonstrated in previous studies; [16][17][18][19][20][21][22][24][25][26][27][28][29][30][31][32][33][34]36 and the relevance of these findings to the clinical setting is supported by in vivo lung and breast xenograft models. 17,21 To corroborate that the Her-2 receptors expressed by the breast cancer cells are functional, we evaluated cell death in MDA-MB-453 and MCF-7 lines treated with increasing amounts of Herceptin (0-100 mg/ ml).…”

“…[18][19][20][21][22][23]38 It is now known that mda-7 activates various signaling pathways in a cell-type-specific manner, and that these pathways ultimately converge on mitochondrial destruction and induction of apoptosis. 21,22,[24][25][26][27][28][29][30] However, in spite of its clear tumor-suppressive effects, the mechanisms by which Ad-mda7 induces cytotoxicity have not been fully characterized. Our group has previously demonstrated that Ad-mda7, as a single agent therapy, induces apoptosis and inhibits growth in pancreatic, lung and breast cancer cells.…”

Enhanced delivery of mda-7/IL-24 using a serotype chimeric adenovirus (Ad.5/3) improves therapeutic efficacy in low CAR prostate cancer cells

“…26 Caspase 3/7 activities were measured using the Caspases-Glo 3/7 Assay Kit (Promega, Madison, MI) according to the manufacturer's instructions. For trypan blue cell death assay, cells were harvested by treatment with 0.05% trypsin/0.53 mM EDTA (ethylenediaminetetraacetic acid).…”

“…26 Briefly, cells were incubated with mouse monoclonal anti-CAR antibody for 1 h at 37 1C (1:1000 dilution; Millipore, Billerica, MA), washed, exposed to fluorescein isothiocyanate-conjugated anti-mouse immunoglobulins (1:1000 dilution; Sigma, St Louis, MO) for 1 h at 37 1C in the dark, washed again and analyzed on a FACSCalibur using CellQuest Pro version 5.2 (BD Biosciences, San Jose, CA). Unstained cells, cells stained with secondary antibody only and cells incubated with isotype control primary antibody, followed by secondary antibody, were used as controls.…”