Antibodies blocking adhesion and matrix binding domains of laminin‐332 inhibit tumor growth and metastasis in vivo

Abstract

Laminin-332 (LN-332), which is essential for epithelial cell adhesion and migration, is up-regulated in most invasive carcinomas. Association between LN-332 and carcinoma cell integrins and stroma collagen is thought to be important for tumor growth and metastasis. Here, we show that function blocking LN-332 antibodies interfering with cellular adhesion and migration in vitro evoke apoptotic pathways. The antibodies also target epithelial tumors in vivo. Antibodies against the cell binding domain of the a3 chain of LN-332 inhibited tumor growth by up to 68%, and antibodies against the matrix binding domains of the b3 and c2 chains significantly decreased lung metastases. The LN-332 antibodies appear to induce tumor cell anoikis and subsequent programmed cell death and reduce migration by interfering with tumor cell matrix interactions. ' UICCKey words: laminin; basement membranes; metastasis; immunotherapy Laminins are trimeric basement membrane (BM) glycoproteins with roles in cell adhesion, proliferation, migration and differentiation. In mammals, 5 genetically distinct a, 3b and 3g chains can form at least 14 different combinations of these chains.1,2 Laminin-332 (LN-332, previously termed laminin-5) that has chain composition a3:b3:g2 ( Supplementary Fig. 1) is essential for anchorage of epithelial cells and specifically found in epithelial BMs.3-5 LN-332 defects lead to detachment of epithelia and the fatal skin blistering disease junctional epidermolysis bullosa.6-8 LN-332 also has a role in proliferation and locomotion of epithelial cells, such as in keratinocytes of healing wounds.9,10 The globular domain (Gdomain) of the a3 chain binds to the cell surface through integrin receptors a6b4 and a3b1 11 and evokes anti-apoptotic signals through focal adhesion kinase, 12,13 while the short arms of the b3 and g2 chains bind to Type VII collagen in the stroma. 14 LN-332 is up-regulated in various epithelial cancers, including colon, gastric, mammary duct and squamous cell carcinomas, as well as melanomas, [15][16][17][18] but not in mesenchymal cancers. 15,16 High expression of the g2 chain of LN-332 has been found to correlate with poor prognosis of cervical squamous cell carcinomas.19 LN-332 is also a major scattering factor stimulating invasive and metastatic capacity of several tumor cell lines in vitro. 20,21 In the cancer tissue, the protein is primarily expressed at the invasive front, as well as in micro-metastases. Down-regulation of LN-332 has been reported in epithelial prostate cancer 22 and also in breast cancers. 23LN-332 expression has been associated with tumorigenesis. Thus, when HT1080 tumor cells constitutively expressing laminin b3 and g2 chains but not a3 were transfected with laminin a3 cDNA, the cells grew significantly larger tumors in nude mice than untransformed cells. 24 Moreover, LN-332 negative (as well as a4 integrin negative) keratinocytes did not become tumorigenic upon transfection with Ras-IjBa in contrast to normal keratinocytes. 25 Since most cancers are of epithelial origi...

The Cohesive Metastasis Phenotype in Human Prostate Cancer

“…LBI expression patterns have clinical significance for several epithelial-derived malignancies, for example the α6β1 integrin receptor is conserved in prostate cancer [39], is expressed on prostate tumor cells undergoing PNI [13], and acts as a marker in the aggressive phenotype of tumor cells during cancer progression [14,32,60,64]. The LBIs are especially associated with the invasion and metastasis of human prostate cancer, traversing through muscle [39,65–69]. …”

The key feature for early migratory processes

“…Blocking or interfering with any of these processes affects in the mildest case just migration speed but typically inhibits motility or even leads to cell death. 34,35 Adhesion molecules as integrins or cadherins are located in filopodia and are the first molecules getting in contact with the environment upon migration. Interestingly, depending on the analyzed cell type filopodial, sensing does not necessarily have to end up in cell matrix adhesions as described, for example, 3T3 fibroblasts during cell spreading.…”

Functional Diversity of Laminins

“…Numerous reports have described increased expression of the LM-332 γ2 chain as a prognostic marker for multiple types of invasive carcinomas by using immunohistology and serum enzyme-linked immunosorbent assay analysis (Katayama et al 2005;Marinkovich 2007;Pyke et al 1994Pyke et al , 1995. Furthermore, antibodies against LM-332 target primary mouse carcinoma and its lung metastasis in vivo (Salo et al 2009), and they significantly inhibit tumor proliferation and metastatic dissemination, possibly by increasing apoptosis. A monoclonal antibody targeting the LG4-5 motifs of the laminin α3 chain induced squamous cell carcinoma cell apoptosis in vivo and thus inhibited tumor proliferation, but it did not affect normal epithelial tissue adhesion because the LG4-5 domain is normally cleaved before LM-332 is integrated into hemidesmosomes (Tran et al 2008).…”