Laminin α5-derived peptides modulate the properties of metastatic breast tumour cells

Abstract

The basement membrane protein laminin-511 has been implicated in breast cancer progression and metastasis. To identify peptides from LM-511 that modulate the metastatic properties of breast tumours, we screened laminin alpha 5 chain-derived peptides for their ability to promote adhesion of metastatic mammary carcinoma cells. Two selected adhesive peptides, α5A13b (FHVAYVLIKF) from the LN domain and A5G27 (RLVSYNGIIFFLK) from the LG-globular domain, were further characterised for their inhibitory properties against LM-511 activities in vitro and metastasis in vivo. In vitro, these peptides strongly inhibited LM-511-dependent adhesion and migration of highly metastatic 4T1.2 mammary carcinoma cells. In addition, A5G27 but not α5A13b significantly reduced breast tumour cell proliferation and inhibited laminin-511-induced matrix metalloproteinase-9 expression. Surprisingly, despite its potent inhibitory activity in vitro, A5G27 promoted rather than inhibited 4T1.2 experimental pulmonary metastasis in vivo, regardless of its route of administration. Adhesion of 4T1.2 cells to A5G27 was not inhibited by antibodies directed against α6, β1 or β3 integrins or CD44 but was significantly reduced in the presence of heparin suggesting a role for cell surface glycans. Treatment of the cells with α-L-fucosidase but not neuraminidase or heparinase II also partially inhibited cell adhesion to A5G27 and to LM-511 indicating that these interactions are mediated in part via terminal fucosyl residues. Overall, these results show that LMα5 peptides exhibit distinct functional properties in vitro and in vivo and suggest that interactions between the RLVSYNGIIFFLK sequence present in LM-511 and cell surface glycans may regulate LM-511 metastatic properties in vivo.

Integrin α3β1 Can Function to Promote Spontaneous Metastasis and Lung Colonization of Invasive Breast Carcinoma

“…Pouliot and colleagues have reported that a bone-metastatic subclone of 4T1 cells expresses LM-511, which may be an important regulator of metastastic colonization in this system (14,63,64). Immunostaining cultures of our wild type, α3si, and α3Rx cells for LM-511 revealed that all three of our 4T1 cell lines also secrete abundant LM-511, some of which seems to be cell-associated (Fig.…”

Functional and molecular characterisation of EO771.LMB tumours, a new C57BL/6-mouse-derived model of spontaneously metastatic mammary cancer

“…Gelatinase assays were completed as described previously ( Kusuma et al, 2011 ), with minor modifications. Briefly, the cells (5×10 5 /400 μl SFM) were incubated for 24 hours at 37°C and secreted proteins in the supernatants separated by SDS-PAGE on 8% polyacrylamide gels supplemented with 1% bovine gelatin.…”

Laminin-511

“…(1) Uncontrolled growth of the primary tumor and the loss of myoepithelial-derived LM-111 and LM-332 contribute to the initial disruption of tissue organization 36 , 41 , 44 . Sustained expression of LM-511 further enhances the breakdown of the surrounding basement membrane through induction of MMP-2/9 gelatinases 73 , 90 resulting in exposure of tumor cells to the surrounding stroma. (2) Under the influence of stromal factors, tumor cells undergo EMT and loss of cell-cell contacts.…”

“…(3) Changes in the composition of LM isoforms in the tumor vasculature and the abundance of LM-511 are likely to contribute to tumor cell attachment and intravasation 24 , 29 , 30 . (4) Homing of circulating tumor cells (CTC) and invasion into metastatic sites is mediated through α3β1 integrin interaction with vascular LMs (including LM-511) and MMP-9 proteolytic activity 64 , 73 , 91 . Binding of integrin α6β1 or α6β4 to endogenous LM-332 or LM-511 (in organs rich in these isoforms) promotes survival and growth of disseminated tumor cells (DTC) 62 , 68 , 69 .…”