Article Text

Download PDFPDF
Expression and heterodimer-binding activity of Ku70 and Ku80 in human non-melanoma skin cancer


Background: Experimental data suggest that exposure to ultraviolet radiation may indirectly induce DNA double-strand breaks.

Aim: To investigate the contribution of the non-homologous end-joining repair pathway in basal and squamous cell carcinomas.

Methods: Levels of Ku70 and Ku80 proteins were determined by immunohistochemical analysis and Ku70–Ku80 heterodimer-binding activity by electrophoretic mobility shift assay. Matched pathological normal margins and skin from healthy people were used as controls.

Results: A significant increase in Ku70 and Ku80 protein levels was found for both tumour types as compared with normal skin (p<0.001). Squamous cell carcinoma showed increased immunostaining as compared with basal cell tumours (p<0.02). A direct correlation was found between Ku70 and Ku80 protein levels and expression of the proliferation markers Ki-67/MIB-1 (p<0.02 and p<0.002, respectively) in basal cell carcinoma. DNA binding activity was increased in basal cell carcinoma samples as compared with matched skin histopathologically negative for cancer (p<0.006). In squamous cell carcinomas, however, the difference was significant only with normal skin (p<0.02) and not with matched pathologically normal margins.

Conclusions: Overall, an up regulation of the Ku70 and Ku80 protein levels seems to correlate only with tumour proliferation rate. As non-homologous end joining is an error-prone mechanism, its up regulation may ultimately increase genomic instability, contributing to tumour progression.

  • BCC, basal cell carcinoma
  • DSB, double-strand break
  • EMSA, electrophoretic mobility shift assay
  • IHC, immunohistochemical
  • NHEJ, non-homologous end joining
  • NMSC, non-melanoma skin cancer
  • SCC, squamous cell carcinoma
  • TBS, TRIS-buffered saline

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.