Growth factor-sensitive molecular targets identified in primary and metastatic head and neck squamous cell carcinoma using microarray analysis

Polypeptide growth factors play key roles in the processes of cell migration and invasion. In this study, we have used cDNA microarrays to identify target genes whose expression is differentially modulated by the growth factors TGFβ and EGF. HN4 and HN12 cell lines, established from primary tumor and a lymph node metastasis arising in one patient with head and neck squamous cell carcinoma, were treated with 2 nM EGF or 50 pM TGFβ for 24 h and extracted RNA was used to prepare labeled cDNAs which were hybridized to NCI UniGem 2.0 cDNA microarrays containing 9128 features. Results revealed constitutive overexpression of 41 genes and underexpression of 109 genes in metastatic HN12 compared to HN4 under conditions of serum withdrawal. Furthermore, TGFβ treatment resulted in relative upregulation of 53 genes and downregulation of 91 genes in HN12 compared with HN4, whereas cells treated with EGF showed relative upregulation of 67 genes and downregulation of 113 genes. Partial overlap was found between TGFβ and EGF-modulated gene sets. Results were verified for a subset of each category using quantitative PCR, western blotting and zymography. The data indicate that TGFβ and EGF differentially affect gene expression in primary and metastatic HNSCC cells, and likely contribute to the invasive properties of metastatic cells through regulation of both common and specific mediators for each growth factor.