elastin and Thyroid-Neoplasms

Insulin-like peptide 3 (INSL3) is present in hyperactive and neoplastic thyrocytes, but the functional role of this relaxin-like peptide hormone during carcinogenesis in the thyroid gland is currently unknown. We generated new cell models of stable transfectants of the human follicular thyroid carcinoma cell line FTC-133 expressing and secreting bioactive human INSL3. These transfectants displayed higher intracellular ATP levels, but INSL3 failed to act as a promoter of growth. The acquisition of an invasive tumor cell phenotype with local tissue invasion represents the beginning of a number of events leading to metastasis, the major cause of fatal outcome in cancer patients. Here we demonstrate a function of INSL3 in elastin degradation, which is considered an early step during basal membrane penetration and tissue invasion by tumor cells. INSL3 markedly increased the production of the lysosomal enzymes cathepsin-L and cathepsin-D. Enhanced secretion of the elastinolytic cathepsin-L was associated with increased elastinolytic activity of FTC-133-INSL3 transfectants. Thus, we provide the first evidence that the INSL3 peptide can promote early tumor cell invasiveness in human thyroid carcinoma cells by enhancing their metabolic activity and elastin-degrading potential.

Topics: Adenosine Triphosphate; Cathepsin D; Cathepsin L; Cathepsins; Cell Line, Tumor; Cysteine Endopeptidases; Elastin; Fluorescent Antibody Technique; Humans; Hydrolases; Insulin; Lysosomes; Neoplasm Invasiveness; Proteins; Reverse Transcriptase Polymerase Chain Reaction; Thyroid Neoplasms

The intracellular domains of the membrane-anchoring regions of some precursors of epidermal growth factor (EGF) family members have intrinsic biologic activities. We have determined the role of the human proEGF cytoplasmic domain (proEGFcyt) as part of the proEGF transmembrane-anchored region (proEGFctF) in the regulation of motility and elastinolytic invasion in human thyroid cancer cells. We found proEGFctF to act as a negative regulator of motility and elastin matrix penetration and the presence of proEGFcyt or proEGF22.23 resulted in a similar reduction in motility and elastinolytic migration. This activity was counteracted by EGF-induced activation of EGF receptor signaling. Decreased elastinolytic migratory activity in the presence of proEGFctF and proEGFcyt/proEGF22.23 coincided with decreased secretion of elastinolytic procathepsin L. The presence of proEGFctF and proEGFcyt/proEGF22.23 coincided with the specific transcriptional up-regulation of t-SNARE member SNAP25. Treatment with siRNA-SNAP25 resulted in motility and elastin migration being restored to normal levels. Epidermal growth factor treatment down-regulated SNAP25 protein by activating EGF receptor-mediated proteasomal degradation of SNAP25. These data provide first evidence for an important function of the cytoplasmic domain of the human proEGF transmembrane region as a novel suppressor of motility and cathepsin L-mediated elastinolytic invasion in human thyroid carcinoma cells and suggest important clinical implications for EGF-expressing tumors.

Topics: Animals; Carcinoma; Cathepsin L; Cathepsins; Cell Movement; Cysteine Endopeptidases; Cytoplasm; Down-Regulation; Elastin; Epidermal Growth Factor; Female; Humans; Hydrolysis; Male; Models, Biological; Neoplasm Invasiveness; Protein Precursors; Protein Structure, Tertiary; Thyroid Neoplasms; Transfection; Tumor Cells, Cultured

The role of members of the insulin-like superfamily in human thyroid carcinoma is primarily unknown. Here we demonstrate the presence of RLN2 relaxin and relaxin receptor LGR7 in human papillary, follicular, and undifferentiated anaplastic thyroid carcinoma suggesting a specific involvement of relaxin-LGR7 signaling in thyroid carcinoma. Stable transfectants of the LGR7-positive human follicular thyroid carcinoma cell lines FTC-133 and FTC-238 that secrete bioactive proRLN2 revealed this hormone to act as a multifunctional endocrine factor in thyroid carcinoma cells. Although RLN2 did not act as a mitogen, it acted as an autocrine/paracrine factor and significantly increased anchorage-independent growth and thyroid carcinoma cell motility and invasiveness through elastin matrices. Suppression of LGR7 expression by LGR7-siRNA abolished the RLN2-mediated accelerated tumor cell motility. The increased elastinolytic activity correlated with enhanced production and secretion of the lysosomal proteinases cathepsin-D (cath-D) and cath-L forms hereby identified as new RLN2 target molecules in human neoplastic thyrocytes. We found the intracellular distribution of procath-L specifically altered in RLN2 transfectants, providing first evidence for selective actions of relaxin on the powerful elastinolytic cath-L production, storage, and secretion in thyroid carcinoma cells. Thus, relaxin enhances the oncogenic potential and acts as novel endocrine modulator of invasiveness in human thyroid carcinoma cells.

Topics: Adolescent; Adult; Aged; Carcinoma; Cathepsins; Cell Line, Tumor; Cell Movement; Child; Elastin; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Membrane Proteins; Middle Aged; Neoplasm Invasiveness; Protein Transport; Receptors, G-Protein-Coupled; Receptors, Peptide; Relaxin; RNA, Messenger; Signal Transduction; Thyroid Neoplasms; Transfection; Tumor Cells, Cultured