Abstract
Tuberous sclerosis complex (TSC) is a tumor suppressor gene disorder characterized by mutations in the TSC1 or TSC2 genes. These mutations lead to the development of benign tumors involving smooth muscle cells, causing life-threatening lymphangioleiomyomatosis. We isolated and characterized two types of cells bearing a mutation in TSC2 exon 18 from a renal angiomyolipoma of a TSC patient: one population of alpha-actin-positive smooth muscle-like cells with loss of heterozygosity for the TSC2 gene (A(+) cells) and another of nonloss of heterozygosity keratin 8/18-positive epithelial-like cells (R(+) cells). Unlike control aortic vascular smooth muscle cells, A(+) cells required epidermal growth factor (EGF) to grow and substituting EGF with insulin-like growth factor (IGF)-1 failed to increase the cell number; however, omission of EGF did not cause cell loss. The A(+) cells constantly released IGF-1 into the culture medium and constitutively showed a high degree of S6K phosphorylation even when grown in serum-free medium. Exposure to antibodies against EGF and IGF-1 receptors caused a rapid loss of A(+) cells: 50% by 5 days and 100% by 12 days. Signal transduction mediated by EGF and IGF-I receptors is therefore involved in A(+) cell survival. These results may offer a novel therapeutic perspective for the treatment of TSC complications and lymphangioleiomyomatosis.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / metabolism
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Adult
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Angiomyolipoma / genetics
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Angiomyolipoma / pathology*
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Aorta / cytology
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Cell Culture Techniques
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Cell Proliferation
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Cell Survival / drug effects
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DNA Mutational Analysis
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Epidermal Growth Factor / pharmacology
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Epidermal Growth Factor / physiology*
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Exons
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Female
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Fluorescein-5-isothiocyanate
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Fluorescent Antibody Technique, Indirect
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Fluorescent Dyes
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Genes, Tumor Suppressor
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Genetic Markers
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Humans
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Immunohistochemistry
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Insulin-Like Growth Factor I / metabolism
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Insulin-Like Growth Factor I / pharmacology
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Keratins / metabolism
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Loss of Heterozygosity
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Microsatellite Repeats
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Muscle, Smooth / chemistry
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Muscle, Smooth / cytology
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Muscle, Smooth / growth & development*
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Muscle, Smooth / metabolism
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Muscle, Smooth, Vascular / chemistry
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Muscle, Smooth, Vascular / cytology
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Muscle, Smooth, Vascular / growth & development
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Muscle, Smooth, Vascular / metabolism
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Mutation
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Phosphorylation
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Rhodamines
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Ribosomal Protein S6 Kinases, 70-kDa / metabolism
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Tuberous Sclerosis / genetics
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Tuberous Sclerosis / pathology*
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Tuberous Sclerosis Complex 1 Protein
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Tuberous Sclerosis Complex 2 Protein
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism*
Substances
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Actins
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Fluorescent Dyes
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Genetic Markers
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Rhodamines
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TSC1 protein, human
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TSC2 protein, human
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Tuberous Sclerosis Complex 1 Protein
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Tuberous Sclerosis Complex 2 Protein
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Tumor Suppressor Proteins
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Epidermal Growth Factor
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Insulin-Like Growth Factor I
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Keratins
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Ribosomal Protein S6 Kinases, 70-kDa
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ribosomal protein S6 kinase, 70kD, polypeptide 2
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Fluorescein-5-isothiocyanate