Abstract
Purpose: :
Our laboratory has previously described an v integrin conditional knock-out mouse model that develops spontaneous conjunctival and eyelid squamous cell carcinoma (SCC). We further reported the expression patterns of v integrin in human conjunctival and eyelid SCCA. In the current study we analyzed the expression of the β8 integrin protein in human non-malignant and SCC samples. We further report on the development of immortalized human v "knock-down" skin epithelial cells that may have similar properties to tumor cells in the murine knock-out model.
Methods: :
Immunohistochemistry (IHC) using an anti-β8 integrin antibody was performed on ten human eyelid SCC tumors samples. Lentiviral-delivered shRNAs were used to silence v integrin gene expression in primary human keratinocytes. These cells, as well as control cells infected with empty lentivirus, were immortalized with a retrovirus expressing the human papilloma virus E6/E7 oncoproteins. Immortalized cells were plated on cover slips coated with the v integrin ECM ligands laminin (LM), fibronectin (FN), or vitronectin (VN). Immunofluorescence (IF) staining to identify the actin cytoskeleton and focal contacts was performed to compare morphologies of the two cell types.
Results: :
v and β8 integrin protein expression was detected in non-malignant human eyelid skin and conjunctival epithelial cells. Furthermore, v and β8 integrin protein was expressed at higher levels in poorly differentiated areas of the human eyelid SCC samples. IF staining of the v KD cells displayed an abnormal actin cytoskeletal network with less focal cell contacts to the ECM, as compared to the control.
Conclusions: :
We have previously shown the v integrin subunit shows increased expression in poorly differentiated areas of human head and neck SCC. Our current work involves the β8 integrin subunit, which pairs only with the v subunit, and reveals a similar expression pattern. Therefore, the integrin vβ8 may play a central role in the pathogenesis of more malignant SCC phenotypes. Additionally, v KD human keratinocytes display strikingly abnormal actin cytoskeletal networks as well as decreased ECM focal cell contacts, which may provide mechanistic insights into tumorogenesis and invasiveness in vivo.
Keywords: tumors • eyelid • gene/expression