Figure 2.

Detection of HERV-K Env protein expression in pancreatic cancer cells. A, expression of HERV-K Env protein was detected by immunofluorescence staining in seven PC cell lines as well as HPDE-E6E7 cells using 6H5 mAb (left panel). The expression of HERV-K Env SU protein on the cell membrane of Panc-1 or Panc-2 cells was demonstrated by confocal microscopy after immunofluorescence staining with 6H5 mAb; the control mIgG showed no staining (right panel). DAPI (blue color) was used for nuclear counterstain. B, expression of HERV-K Env protein was detected by immunoblot in seven PC cell lines but not in HPDE-E6E7 cells, using 6H5 mAb. ACTB was used as the control. The expression of HERV-K Env protein from high to low is AsPC-1 (3.58 fold), BxPC-3 (2.70 fold), MAI-PaCa-2 (2.11 fold), SU8686 (2.02 fold), Colo-357 (1.67 fold), Panc-1 (1.10 fold), and Panc-2 (1 fold). No expression of HERV-K was detected in HPDE-E6 E7 cells using Image J. C, expression of HERV-K Env protein on the various pancreatic cell lines was determined by cell ELISA using 6H5 mAb (left panel); mIgG was used as the control (right panel). The expression of HERV-K Env protein was detected to a greater extent in all seven PC cell lines tested than in HPDE-E6E7. D, strong expression of HERV-K was detected by immunohistochemistry in most PC tissues containing poorly differentiated adenocarcinoma. HERV-K was not expressed in normal or matched uninvolved, non-neoplastic pancreatic tissues. The expression of HERV- K was compared in a patient with moderate differentiated adenocarcinoma including tumor biopsy and matched non-neoplastic pancreatic tissues.