BACKGROUND : HOX gene expression is altered in many cancers; previous microarray revealed changes in HOX gene expression in
head and neck squamous cell carcinoma (HNSCC), particularly HOXD10.
METHODS : HOXD10 expression was assessed by qPCR and immunoblotting in vitro and b immunohistochemistry (IHC) in tissues.
Low-expressing cells were stably transfected with HOXD10 and the phenotype assessed with MTS, migration and adhesion assays
and compared with the effects of siRNA knockdown in high-HOXD10-expressing cells. Novel HOXD10 targets were identified
using expression microarrays, confirmed by reporter assay, and validated in tissues using IHC.
RESULTS : HOXD10 expression was low in NOKs, high in most primary tumour cells, and low in lymph node metastasis cells, a
pattern confirmed using IHC in tissues. Overexpression of HOXD10 decreased cell invasion but increased proliferation, adhesion
and migration, with knockdown causing reciprocal effects. There was no consistent effect on apoptosis. Microarray analysis
identified several putative HOXD10-responsive genes, including angiomotin (AMOT-p80) and miR-146a. These were confirmed as
HOXD10 targets by reporter assay. Manipulation of AMOT-p80 expression resulted in phenotypic changes similar to those on
manipulation of HOXD10 expression.
CONCLUSIONS : HOXD10 expression varies by stage of disease and produces differential effects: high expression giving cancer cells
a proliferative and migratory advantage, and low expression may support invasion/metastasis, in part, by modulating AMOT-p80