A role for relaxin and INSL3 in tumor cell invasiveness

The peptide hormones relaxin and INSL3 are present in human papillary, follicular and dedifferentiated thyroid carcinomas but not in normal thyroid tissues. To investigate the potential role of both relaxin family members for thyroid carcinoma motility & invasion, we created and characterized stable transfectants of the follicular thyroid carcinoma cell line FTC-133 over-expressing either H2 relaxin or human INSL3. Soft agar assays revealed a significantly increased number of small-sized colonies, particularly with H2, indicating enhanced capacity for anchorage-independent growth of both H2 and INSL3 transfectants. We employed a modified Boyden chamber assay to investigate the motility and migration. Both H2 and INSL3 FTC-133 transfectants demonstrated increased motility through 8µm filter pores. FTC-133 transfectants over-producing H2 as opposed to INSL3 transfectants or empty plasmid controls displayed increased tumor cell migration through a collagen matrix which was significantly decreased in the presence of the MMP inhibitor GM6001. Westernblot analysis in both clones revealed significantly decreased expression of membrane type MT1 MMP and TIMP3 and increased levels of ADAM23. The mRNA data showed downregulation of ADAMTS1, ADAMTS5 or ADAM12. Moreover other extracellular matrix affecting proteinases – Cathepsin L and D demonstrated differentiated producing pattern and secretion in relaxin and INSL3 clones.

Supported by the DFG.