transforming-growth-factor-beta and Tuberous-Sclerosis

During the past two years, new molecular targets have been discovered which link cell cycle, cell proliferation and cellular growth. It has become more and more evident that whereas gain-of-function mutations in specific genes can lead to cancer, genomic instability plays also an important role in tumour progression. With examples taken from the recent literature, we describe in this short review crucial findings on the molecular mechanisms controlling cell cycle and proliferation. We illustrate how specific combinations of proto-oncogenes alterations can result in tissue-specific tumours. Finally, impairment of the interactions of a cancer cell with its surrounding neighbours is also shown to participate in the progression toward aggressive phenotypes.

Topics: Animals; Antineoplastic Agents, Phytogenic; CDC2-CDC28 Kinases; Cell Cycle; Cell Division; Cell Transformation, Neoplastic; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinases; Cyclins; Disease Progression; Drug Resistance; Fusion Proteins, bcr-abl; Humans; Mice; Mutation; Neoplasm Metastasis; Neoplasm Proteins; Neoplasms; Neovascularization, Pathologic; Neural Cell Adhesion Molecules; Paclitaxel; Protein Serine-Threonine Kinases; Radiation Tolerance; Rats; Thrombospondins; Transforming Growth Factor beta; Tuberous Sclerosis

Genetic studies of families at high risk for developing malignant and benign renal neoplasms led to cloning of genes whose alteration results in tumor formation. These genes are either tumor suppressors (VHL, TSC) or oncogenes (MET). Their significance in understanding oncogenesis extends far beyond the familial syndromes. The identification of these genes and the elucidation of their biochemical functions are likely to facilitate (1) our understanding of the full clinical spectrum of the corresponding diseases, (2) genetic counseling, and (3) rational design of effective strategies to prevent and/or treat familial and sporadic forms of these neoplasms.

Topics: Animals; Carcinoma, Renal Cell; Cloning, Molecular; Elongin; Genes, Tumor Suppressor; Genotype; Humans; Kidney Diseases, Cystic; Kidney Neoplasms; Ligases; Middle Aged; Models, Genetic; Mutation; Pheochromocytoma; Proteins; Syndrome; Transcription Factors; Transforming Growth Factor beta; Tuberous Sclerosis; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; von Hippel-Lindau Disease; Von Hippel-Lindau Tumor Suppressor Protein

Patients with tuberous sclerosis complex (TSC) develop fibrous tumours in the brain, skin, kidney, heart and lungs due to TSC1/2 mutations. In the skin, patients develop angiofibromas that have vascular and fibrotic components in which transforming growth factor (TGF)-β and matrix metalloproteinase (MMP)-2 are important.. To investigate if the TGF-β axis and MMP-2 play an important role in the pathogenesis of TSC angiofibromas.. Samples from TSC angiofibromas and normal skin were measured for expression of TGF-β and MMP-2 by immunohistochemistry and real-time polymerase chain reaction. Fibroblasts grown from TSC angiofibromas (TSC fibroblasts) were incubated with TGF-β. Expression of ERK, AKT and S6K was measured by Western blotting, and MMP-2 expression and activity were determined by enzyme-linked immunosorbent assay and gelatin zymography, respectively.. There was an increase in the expression of TGF-β and MMP-2 in TSC tumours compared with those in normal skin. The baseline expression of MMP-2 was increased in conditioned medium from TSC fibroblasts. In addition, TGF-β enhanced MMP-2 production and activity, which could be abrogated by pretreatment with an AKT inhibitor (LY294002) but not with rapamycin. Finally, there was a significant colocalization of TGF-β and MMP-2 in the TSC tumours.. There is an increase of MMP-2 as a result of TGF-β acting through AKT in TSC tumour cells. This regulation of the TGF-β-AKT-MMP-2 axis is independent of mammalian target of rapamycin (mTOR) signalling. In addition to targeting the mTOR pathway, targeting TGF-β simultaneously could block dysregulated tissue remodelling in TSC tumours.

Topics: Angiofibroma; Cells, Cultured; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Humans; Immunohistochemistry; Matrix Metalloproteinase 2; Polymerase Chain Reaction; Proto-Oncogene Proteins c-akt; Transforming Growth Factor beta; Tuberous Sclerosis

Balloon cells (BCs) in focal cortical dysplasia (FCD) and giant cells (GCs) in tubers of the tuberous sclerosis complex (TSC) share phenotypic similarities. TSC1 or TSC2 gene mutations in TSC lead to mTOR pathway activation and p70S6kinase (phospho-S6K) and ribosomal S6 (phospho-S6) protein phosphorylation. Phospho-S6K, phospho-S6, and phospho-S6K-activated proteins phospho-STAT3 and phospho-4EBP1 were detected immunohistochemically in GCs, whereas only phospho-S6 was observed in BCs. Expression of four candidate gene families (cell signaling, cell adhesion, growth factor/receptor, and transcription factor mRNAs) was assayed in single, microdissected phospho-S6-immunolabeled BCs and GCs as a strategy to define whether BCs and GCs exhibit differential transcriptional profiles. Among 60 genes, differential expression of 24 mRNAs distinguished BCs from GCs and only 4 genes showed similar expression profiles between BCs and GCs. Tuberin mRNA levels were reduced in GCs from TSC patients with TSC2 gene mutations but were unchanged in BCs. Phospho-S6K, -S6, -STAT3, and -4EBP1 expression in GCs reflects loss of hamartin-tuberin-mediated mTOR pathway inhibition. Phospho-S6 expression alone in BCs does not support mTOR cascade activation in FCD. Differential gene expression profiles in BCs and GCs supports the hypothesis that these cell types derive by distinct pathogenic mechanisms.

Topics: Adolescent; Adult; Cell Count; Cerebral Cortex; Child; Child, Preschool; DNA-Binding Proteins; Epilepsy; Eukaryotic Initiation Factors; Female; Gene Expression Regulation; Humans; Immunohistochemistry; In Situ Hybridization; Infant; Insulin-Like Growth Factor II; Male; Microdissection; Protein Kinases; Reverse Transcriptase Polymerase Chain Reaction; Ribosomal Protein S6; Ribosomal Protein S6 Kinases, 70-kDa; RNA, Messenger; STAT3 Transcription Factor; TOR Serine-Threonine Kinases; Trans-Activators; Transforming Growth Factor beta; Tuberous Sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder associated with an alteration of the TSC2 tumor suppressor gene which encodes for the protein product tuberin. The disease is characterized by the development of hamartomas, e.g. cutaneous angiofibromas which consist of vascular cells, interstitial cells, and normal components of the skin. The Eker rat model, an animal model of inherited cancer, has been shown to carry a mutation of TSC2.. Immunohistochemical analyses of human angiofibromas were performed using antibodies directed against tuberin and angiogenic growth factors. Proliferation of human dermal microvascular endothelial cells (HDMEC) was determined after incubation with the supernatants of TSC2 (+/+) and TSC2 (-/-) rat embryonic fibroblasts (REF) that were derived from the Eker strain.. Loss of the expression of tuberin was observed in the interstitial cells of 13 of 39 angiofibromas. The expression of tuberin was retained in the vascular cells. In all analyzed angiofibromas, the angiogenic factors bFGF, PD-ECGF, VEGF and angiogenin were detected in the interstitial cells and/or vascular cells. Expression of PDGF-B and TGF-beta1 was weak. Tissue culture supernatants from TSC2 (-/-) REF stimulated the growth of HDMEC significantly more than supernatants from TSC2 (+/+) REF.. A functional loss of tuberin may stimulate vascular growth.

Topics: Angiofibroma; Animals; Cells, Cultured; Culture Media, Conditioned; Endothelial Growth Factors; Endothelium; Fibroblast Growth Factor 2; Fibroblasts; Humans; Immunohistochemistry; Lymphokines; Neovascularization, Pathologic; Proto-Oncogene Proteins c-sis; Rats; Rats, Mutant Strains; Repressor Proteins; Ribonuclease, Pancreatic; Thymidine Phosphorylase; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tuberous Sclerosis; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; Vascular Neoplasms