O-linked-N-acetylglucosamine transferase is associated with metastatic spread of human papillomavirus E6 and E7 oncoproteins to the lungs of mice

High-risk human papilloma virus (HPV) 16/18 infections are often found in lung cancer. The cellular mechanisms involved in the metastatic spread of HPV-infected cervical cancer cells remain largely elusive. High O-linked-N-acetylglucosamine (O-GlcNAc) modification has also been observed in lung cancer. In the present study, we assessed the relationship between O-GlcNAc transferase (OGT) and HPV 16/18 E6/E7, or C-X-C chemokine receptor type 4 (CXCR4), in HeLa cells and in lungs of xenografted mice. Depleting OGT with an OGT-specific shRNA significantly decreased levels of E6 and E7 oncoproteins in HeLa cells and xenograft tumors, and reduced tumor formation in vivo. Western blotting and immunofluorescence analysis showed significantly decreased expression levels of E6, E7, and HCF-1 in the lungs of xenografted mice treated with an OGT-specific shRNA compared to those treated with non-targeting shRNA. Additionally, levels of E7 or OGT co-localized with Ki-67 were significantly decreased in the lungs of xenografted mice treated with OGT-specific shRNA compared to those treated with non-targeting shRNA. Moreover, levels of CXCR4 were significantly decreased in HeLa cells and in the lungs of xenografted mice treated with OGT-specific shRNA compared to those treated with non-targeting shRNA; this may be related to reduced adhesion or invasion of circulating HPV-positive tumor cells. These findings provide novel evidence that OGT functions in metastatic spread of HPV E6/E7-positive tumor cells to the lungs through E6/E7, HCF-1 and CXCR4, suggesting OGT might be a therapeutic target for HPV-positive lung cancer.