Relaxin Enhances S100A4 and Promotes Growth of Human Thyroid Carcinoma Cell Xenografts

Abstract

Relaxin increases cell motility and in vitro invasiveness in human thyroid carcinoma cells but the underlying molecular mechanisms of this action are largely unknown. In the present study, we show that relaxin transcriptionally upregulates the calcium-binding protein S100A4 (metastasin) and increases the cytosolic 10-kDa monomer and the 20-kDa dimer form of S100A4 in human thyroid carcinoma cells. The relaxin-induced increase in cell motility was blocked completely when S100A4 expression was diminished using an S100A4 small interfering RNA knockdown approach. We have shown previously the expression of the insulin-like family member relaxin in human thyroid carcinoma tissues but not in benign thyroid tissues. Human thyroid carcinoma tissues expressing relaxin also stained positive for S100A4. In nude mouse experiments, human thyroid carcinoma cell transfectants with constitutive expression of relaxin generated large and fast-growing tumors with significantly increased numbers of proliferating cells. We provide evidence in our cell model that the relaxin target protein S100A4 secreted by the thyroid carcinoma transfectants may not only enhance tumor cell motility but also promote xenograft angiogenesis as determined by the higher density of tumor microvessels and the angiogenic potential of S100A4 in in vitro tube formation assays. In conclusion, we have identified S100A4 as a major mediator of the actions of relaxin in thyroid carcinoma cell motility and in vivo thyroid tumor angiogenesis.

Recombinant H2 relaxin inhibits apoptosis and induces cell proliferation in cultured leiomyoma cells without affecting those in cultured normal myometrial cells

“…We confirmed that treatment with relaxin induced the proliferation of cultured leiomyoma cells by up-regulating PCNA expression levels in a dose-dependent manner but not in normal myometrial cells. Our results are in accordance with reports showing that relaxin can induce proliferation of a variety of cells, including mouse uterine cervix (16), human prostate cancer (17,18), human breast cancer (19), and thyroid cancer (20). Although in mouse uterine cervix relaxin induces proliferation, we demonstrated that relaxin did not induce proliferation in human cultured normal myometrial cells but did induce proliferation in human cultured leiomyoma cells.…”

Relaxin Enhances the Collagenolytic Activity and In Vitro Invasiveness by Upregulating Matrix Metalloproteinases in Human Thyroid Carcinoma Cells

“…Follicular thyroid cancer cells and PC-3 prostate carcinoma cells expressing RLN2 displayed enhanced xenograft growth and angiogenesis (7,69,70). The importance of the RLN/RXFP1 ligand receptor system for tumor growth is also highlighted by 2 sets of in vivo experiments.…”

RAGE Mediates the Pro-Migratory Response of Extracellular S100A4 in Human Thyroid Cancer Cells

“…Dewaxing, antigen retrieval and immunohistochemistry were performed as described previously (15). Sections were probed with the anti-RAGE rabbit primary antibody (1:100) or an isotype control antibody (Sigma) at equivalent protein concentrations overnight at 4⁰C.…”

“…S100A4 gene expression has been described as a marker for poor prognosis in patients with TC (10), serves as an early marker for metastasis in PTC, including papillary microcarcinomas, and correlates with invasiveness in FTC (11)(12)(13). Our group has previously shown that S100A4 production is significantly enhanced by Relaxin/RXFP1 and INSL3/RXFP2 signaling in human TC cells (14,15) and that S100A4 mediates the pro-migratory effects induced by these peptides in TC cells.…”