PARENT SESSION
SLIDE SESSION 14: GROWTH FACTORS IN REPRODUCTIVE TISSUES
Chairs: Andrea Cupp, Barbara Vanderhyden, Wendy Ingman (Trainee)
Univ Ottawa-Lamoureaux 122
1:30 PM-3:30 PM
268
RECOMBINANT HUMAN RELAXIN INCREASES MIGRATION OF RAT MYOBLASTS .
Silvertown, Joshua1, Poterski, Roman1, Summerlee, Alastair1, 1
ABSTRACT- Mammary tumors remain to be a significant cause of mortality and morbidity in females. This research involves the peptide relaxin, which has been traditionally known as a pregnancy hormone involved in the relaxation of the cervix during pregnancy. However, relaxin has been implicated in causing an increase of tumor cell proliferation (Bigazzi et al, 1992) and has been detected at higher levels in neoplastic breast tissue (Tashima et al, 1994). Moreover, relaxin has been shown to be involved in the upregulation of extracellular matrix (ECM) degrading enzymes, called matrix metalloproteinases (MMPs) (Qin et al, 1997). The role of relaxin in the upregulation of MMPs may serve as an essential step for a benign tumor to transform into a malignant state, which provides the platform for the migration and invasion into adjacent tissues. The goal of this research was to develop a reliable in vitro assay to test the effects of recombinant human relaxin (rhRLX) on cell migration. Experiments were conducted to investigate the migratory and invasive effects of rhRLX on rat myoblast (L6) cell lines through a simulated ECM of laminin, in Boyden chambers. The invasion chambers had a tissue culture treated polycarbonate 8.0um porous membrane coated with 10ug of the laminin protein. Each chamber was seeded with 2x105 cells and migration through the membrane was observed at 18, 24, 36, and 48 hours with 0, 10, and 100ng/mL of rhRLX treatments. The experiments were carried out in duplicate three times. At each time point, cells were fixed and stained with Giemsa, permitting the counting of five fields per sample under a light microscope. The results for each period were collated. There was no significant difference between vehicle (saline) and 100 ng/mL rhRLX or in control chambers without the laminin coating. In contrast, L6 cells were significantly more invasive with rhRLX of 10ng/mL, compared to doses of vehicle or 100ng/mL. This study shows that the relaxin doses of 10ng/mL allowed the L6 cells to degrade the ECM laminin network coated on the membrane, thereby permitting cell migration. The mechanism of action is under investigation.
KEY WORDS: relaxin, metastasis, rat myoblast, matrix metalloproteinases