Subject(s)
Congenital Abnormalities/etiology , Larynx/abnormalities , Pulmonary Artery/abnormalities , Pulmonary Artery/diagnostic imaging , Respiratory Sounds/etiology , Diverticulum/diagnostic imaging , Humans , Infant , Male , Tomography, X-Ray Computed , Tracheal Diseases/diagnostic imaging , UltrasonographyABSTRACT
From the conditioned medium of the human colon carcinoma cells, HT-29 5M21 (CM-5M21), expressing a spontaneous invasive phenotype, tumor-associated trypsin inhibitor (TATI) was identified and characterized by proteomics, cDNA microarray approaches and functional analyses. Both CM-5M21 and recombinant TATI, but not the K18Y-TATI mutant at the protease inhibitor site, trigger collagen type I invasion by several human adenoma and carcinoma cells of the colon and breast, through phosphoinositide-3-kinase, protein kinase C and Rho-GTPases/Rho kinase-dependent pathways. Conversely, the proinvasive action of TATI in parental HT29 cells was alleviated by the TATI antibody PSKAN2 and the K18Y-TATI mutant. Stable expression of K18Y-TATI in HT-29 5M21 cells downregulated tumor growth, angiogenesis and the expression of several metastasis-related genes, including CSPG4 (13.8-fold), BMP-7 (9.7-fold), the BMP antagonist CHORDIN (5.2-fold), IGFBP-2 and IGF2 (9.6- and 4.6-fold). Accordingly, ectopic expression of KY-TATI inhibited the development of lung metastases from HT-29 5M21 tumor xenografts in immunodeficient mice. These findings identify TATI as an autocrine transforming factor potentially involved in early and late events of colon cancer progression, including local invasion of the primary tumor and its metastatic spread. Targeting TATI, its molecular partners and effectors may bring novel therapeutic applications for high-grade human solid tumors in the digestive and urogenital systems.
Subject(s)
Autocrine Communication , Colonic Neoplasms/metabolism , Lung Neoplasms/metabolism , Neoplasm Proteins/metabolism , Trypsin Inhibitor, Kazal Pancreatic/metabolism , Adenoma/genetics , Adenoma/metabolism , Adenoma/pathology , Animals , Antibodies, Neoplasm/pharmacology , Autocrine Communication/drug effects , Breast Neoplasms/genetics , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Line, Tumor , Colonic Neoplasms/genetics , Colonic Neoplasms/pathology , Gene Expression Regulation, Neoplastic/drug effects , Humans , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/secondary , Mice , Mice, SCID , Neoplasm Invasiveness , Neoplasm Metastasis , Neoplasm Proteins/genetics , Neovascularization, Pathologic/genetics , Neovascularization, Pathologic/metabolism , Neovascularization, Pathologic/pathology , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Recombinant Proteins/pharmacology , Trypsin Inhibitor, Kazal Pancreatic/genetics , Trypsin Inhibitor, Kazal Pancreatic/pharmacologyABSTRACT
The plasma membrane of epithelial cells and hepatocytes is divided into two separate membrane compartments, the apical and the basolateral domain. This polarity is maintained by intracellular machinery that directs newly synthesized material into the correct target membrane. Apical protein sorting and trafficking require specific signals and different intracellular routes to the cell surface. Some of them depend on the integrity of sphingolipid/cholesterol-enriched membrane microdomains named 'lipid rafts', others use separate transport platforms. Certain characteristics of the heterogeneous population of apical sorting signals are described in this review and cellular factors associated with sorting and transport mechanisms are discussed.
Subject(s)
Cell Polarity/physiology , Receptors, Cell Surface/metabolism , Animals , Cell Membrane/metabolism , Golgi Apparatus/metabolism , Humans , Protein Sorting Signals , Protein TransportABSTRACT
The surface of epithelial cells is composed of apical and basolateral domains with distinct structure and function. This polarity is maintained by specific sorting mechanisms occurring in the Trans-Golgi Network. Peptidic signals are responsible for the trafficking via clathrin-coated vesicles by means of an interaction with an adaptor complex (AP). The basolateral targeting is mediated by AP-1B, which is specifically expressed in epithelial cells. In contrast, the apical targeting is proposed to occur via apical raft carriers. It is thought that apically targeted glycoproteins contain glycan signals that would be responsible for their association with rafts and for apical targeting. However, the difficulty in terms of acting specifically on a single step of glycosylation did not allow one to identify such a specific signal. The complete inhibition of the processing of N-glycans by tunicamycin often results in an intracellular accumulation of unfolded proteins in the Golgi. Similarly, inhibition of O-glycosylation can be obtained by competitive substrates which gave a complex pattern of inhibition. Therefore, it is still unknown if glycosylation acts in an indirect manner, i.e. by modifying the folding of the protein, or in a specific manner, such as an association with specific lectins.
