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. In recent years, the multifunctional peptide hormone relaxin has been identified as an important endocrine player in the reproductive tract, cardiovascular/neural systems, and oncology.1,2 The thyroid was once considered to be a relaxin target tissue with relaxin reported to increase thyroid weight, radioactive iodine uptake, and protein-bound iodination in rats.3,4 Likely because of the crude relaxin preparations used at the time, these results could not be confirmed. 5 No further investigations were reported thereafter using highly purified relaxin preparations to validate a potential role of relaxin in thyroid tissues and thyroid cell lines. Some 40 years later, the discovery of the G-protein-coupled relaxin-like receptors LGR7 and LGR8 revealed the presence of transcripts for both LGR7 (relaxin receptor) and LGR8 (INSL3/relaxin receptor) in the thyroid gland. 6 -8 Relaxin and the relaxin-like INSL3 have been shown to activate cAMP-dependent signaling pathways by binding to either LGR7 or LGR8. 8 -12 We recently demonstrated the expression and regulation of INSL3 and LGR8 transcripts in human thyroid carcinoma cell lines, identifying hyper-and neoplastic human thyrocytes as a new source and target of the actions of INSL3 and a novel INSL3 splice variant. 8,13 Although still primarily undefined, relaxin appears to have oncogenic potential in various organs and tissues, including the human thyroid.14 -17 Relaxin affects proliferation and differentiation of MCF-7 human carcinoma cells in a concentration-dependent manner 18 and can modify the extracellular matrix by affecting the expresSupported by the Deutsche Forschungsgemeinschaft (grants KL1249/5-1

Our study reports a preliminary investigation into the role of human H2 relaxin in prostate tumor growth. A luciferase-expressing human prostate cancer cell line, PC-3, was generated and termed PC3-Luc. PC3-Luc cells were transduced with lentiviral vectors engineering the expression of either enhanced green fluorescent protein (eGFP) or both H2 relaxin and eGFP in a bicistronic format. These transduced cells were termed PC3-Luc-eGFP and PC3-Luc-H2/eGFP, respectively. To gauge effects, PC3-Luc-H2/eGFP and PC3-Luc-eGFP cells were injected into NOD/SCID mice and monitored over 6 weeks. PC-3 tumor xenografts overexpressing H2 relaxin exhibited greater tumor volumes compared to control tumors. Circulating H2 relaxin levels in sera increased with the relative size of the tumor, with moderately elevated H2 relaxin levels in mice bearing PC3-Luc-H2/eGFP tumors compared to PC3-Luc-eGFP tumors. Zymographic analysis demonstrated that proMMP-9 enzyme activity was significantly downregulated in H2 relaxin-overexpressing tumors. An advanced angiogenic phenotype was observed in H2 relaxin-overexpressing tumors indicated by greater intratumoral vascularization by immunohistochemical staining of endothelial cells with anti-mouse CD31. Moreover, PC3-Luc-H2/eGFP tumors exhibited increased VEGF transcript by reverse-transcription PCR, compared to basal levels in control animals. Taken together, our study provides the first account of a potential role of H2 relaxin in prostate tumor development. ' 2005 Wiley-Liss, Inc.Key words: PC-3; lentivirus; luciferase; VEGF; MMP-9; H2; prorelaxin In recent years, there has been increasing evidence that suggests a role of relaxin in carcinogenesis. Peptide hormones of the relaxin family are reported to be upregulated in a number of neoplasias, including thyroid, 1 breast, 2 gastrointestinal 3 and the reproductive system. 4,5 Many of the molecules characterized as downstream effectors of relaxin's physiological roles in the cardiovascular system and as agents involved in remodeling of connective tissue have also been linked with tumor growth and sustainability. 6 These molecules, including VEGF and NOS, for example, are established angiogenic agents that promote neovascularization and enhanced blood flow carrying oxygen and cellular nutrients to tumors. 7 The regulation of matrix metalloproteinases (MMPs) is the mechanism considered for relaxin's role in connective tissue remodeling during mammary gland involution, softening of reproductive tissues and dilation of the birth canal. 8 However, the regulation of these enzymes by relaxin have also been suggested as a mechanism for its role in facilitating cancer cell migration and invasion. [9][10][11] Although the biological significance of relaxin in the male remains elusive, the prostate gland appears to be relaxin's main source. 8 In the human, there are 3 relaxin alleles encoding 3 hormones, named H1, H2 and H3. While H2 and H3 relaxins are expressed in a number of tissues, in males their predominant expression is found in the prostate and bra...

SUMMARY1. Extracellular electrical recordings were taken from nine antidromically identified paraventricular units in unanaesthetized, unrestrained rats. Neuronal activity was correlated with the observed events of parturition, i.e. abdominal contractions and delivery of young or placentae.2. The level of spontaneous activity (0 15-3-2 spikes s-1) of all nine units began to increase 15 min before the first signs of abdominal contraction. This accelerated discharge (2-5 fold increase over the background activity) was maintained throughout parturition (58-93 min) and for up to 45 min after delivery of the last placenta.3. All nine neurones displayed at 6-14 s periods of even higher rate of discharge (10-32 spikes s-1) after forceful abdominal contractions. The peak firing rates within these periods of accelerated discharge decreased as labour progressed. 4. Four cells also showed a burst (5-12 s) of high-frequency activity 15-28 s before delivery of either fetuses or placenta. These four units were later classified as oxytocinergic on the basis of their stereotyped activation 10-12 s before reflex milk-ejection.5. The remaining five neurones which did not respond with a burst ofhigh-frequency discharge before delivery were classed as potential vasopressin-producing cells. Four of these units displayed a phasic pattern of activity with periods of activity (5-230 s) alternating with periods of silence (4-31 s).

Hormone antagonists can be effective tools to delineate receptor signaling pathways and their resulting downstream physiological actions. Mutation of the receptor binding domain (RBD) of human H2 relaxin (deltaH2) impaired its biological function as measured by cAMP signaling. In a competition assay, deltaH2 exhibited antagonistic activity by blocking recombinant H2 relaxin from binding to receptors on THP-1 cells. In a flow cytometry-based binding assay, deltaH2 demonstrated weak binding to 293T cells expressing the LGR7 receptor in the presence of biotinylated H2 relaxin. When human prostate cancer cell lines (PC-3 and LNCaP) were engineered to overexpress eGFP, wild-type (WT) H2, or deltaH2, and subsequently implanted into NOD/SCID mice, tumor xenografts overexpressing deltaH2 displayed smaller volumes compared to H2 and eGFP controls. Plasma osmolality readings and microvessel density and area assessment suggest that deltaH2 modulates physiological parameters in vivo. In a second murine model, intratumoral injections of lentivectors engineered to express deltaH2/eGFP led to suppressed tumor growth compared to controls. This study provides further evidence supporting a role for H2 relaxin in prostate tumor growth. More importantly, we report how mutation of the H2 relaxin RBD confers the hormone derivative with antagonistic properties, offering a novel reagent for relaxin research.

This study reports the characterization of a recombinant adenoviral vector containing a tetracycline-regulatable promoter, driving the bicistronic expression of the human H2 preprorelaxin (hH2) cDNA and enhanced green fluorescent protein, via an internal ribosomal entry site. An hH2 ELISA was used to measure the secreted levels of recombinant hH2 in transfected canine (CF33.Mt) and human (MDA-MB-435) mammary cancer cell lines over a 6-d period; secreted peptide peaked on d 2 and 4 for the canine and human cell types, respectively. An unprocessed hH2 immunoreactive form of approximately 18 kDa was identified by Western blotting analysis and confirmed by mass spectrometry, suggesting that prorelaxin remains unprocessed in these cell types. The biological activity of the adenovirally expressed human prorelaxin was measured in the established human monocytic cell line THP-1 cAMP ELISA and in an in vitro Transwell cell migration system. Exogenous recombinant hH2 and adenovirally-mediated delivery of prorelaxin to CF33.Mt cells conferred a significant migratory action in the cells, compared with controls. Cell proliferation assays were performed to discount the possibility that the effect of relaxin was mitogenic. Thus, we have demonstrated that prorelaxin has the ability to facilitate cell migration processes exclusive of its ability to stimulate cell proliferation. In validating this adenovirus-based system, we have created a potential tool for further exploration of the physiology of relaxin in mammalian systems.