Differential modulation of proliferation, matrix metalloproteinase expression and invasion of human head and neck squamous carcinoma cells by c-erbB ligands

Evidence suggests that there is an association between the abnormal express ion of members of the c-erbB receptor tyrosine kinase family and poor progn osis in head and neck squamous cell carcinomas (HNSCC). Until now, the rela tive contributions of different c-erbB ligands to HNSCC progression have no t been clearly defined. In this paper we examined the effects of ligands wi th different c-erbB receptor specificities in terms of their stimulation of HNSCC proliferation, expression of matrix metalloproteinases (MMPs) and in vasion. Heregulin-beta1 (HRG-beta 1; selective c-erbB3/B4 ligand) was found to stimulate proliferation in the majority of cell lines, whereas epiderma l growth factor (EGF; EGFR ligand) and betacellulin (BTC; EGFR/B4 ligand) i nduced variable responses. All three ligands up-regulated multiple MMPs inc luding collagenases, stromelysins, matrilysin and gelatinase B (MMP-9) but had minimal or no effects on gelatinase A (MMP-2), MT1-MMP and tissue inhib itors of MMPs (TIMPs). MMP-9 mRNA was induced to a higher level than other MMPs, although with slower kinetics. HRG-beta 1 was less active than EGF an d BTC at the optimal concentration (relative potency of EGF:BTC:HRG = 3:4:1 ). In vitro invasion through Matrigel was also increased by all three ligan ds in proportion to their MMP up-regulation. A specific anti-EGFR monoclona l antibody (mAb ICR62) inhibited MMP up-regulation, migration and invasion induced by all three ligands, whereas an anti-c-erbB-2 mAb ICR12 inhibited mitogenic and motogenic responses following ligand stimulation but had no e ffect on MMP expression. These results suggest that c-erbB ligands may diff erentially potentiate the invasive phenotype of HNSCC via co-operative indu ction of cell proliferation, migration and proteolysis. The EGFR signalling pathway appears to be the dominant component controlling the proteolytic a nd invasive phenotype in HNSCC, whereas the c-erbB-2 signalling pathway is responsible, in part, for the mitogenic and motogenic effects of ligands.