The origin of squamous cell components in salivary gland tumor has been not yet clarified in detail. The squamous cell differentiation from adenocarcinoma has been reported in various carcinoma by HPV transfection in vitro. The adenocarcinoma cells adjacent to the squamous cell carcinoma components were positive for HPV. This is thought to indicate that after adenocarcinoma cells are transfected with HPV, they undergo morphological changes, and that squamous cell differentiation follows. The purpose of this study were to examine the effects of HPV-16 E6/E7 gene transfection into SGT cell line from human salivary gland adenocarcinoma, and to study the relation between the E6/E7 gene and squamous differentiation. Plasmid pBR322 containing HPV-16 was transfected into cultured SGT cell line using lipofectin method. Hygromycin was used as a selection marker. The presence of HPV E6/E7, transglutaminase 1, and involucrin mRNAs and protein in E6/E7 gene transfected cells was investigated by RT-PCR and immunoslot blot method. The apoptosis index was analysed by flow cytometry. The growth rate of E6/E7 gene transfected cells was reduced. E6/E7 transfected SGT cells increased apoptosis index. Involucrin and TGase I mRNAs by the squamous cell differentiation was most conspicuous in the E6/E7 gene transfected cell compared with non transfected cells. Squamous cell differentiation demonstrated in the transfectedSGT cell line, which expressed E6/E7 fusion gene mRNA.E6/E7 gene transfected cells showed squamous cell differentiation, expressing involucrin and TGase 1 protein by immunoslot blotting. The transfected SGT cell which expressed E6/E7 gene mRNA showed the squamous cell differentiation particularly clearly, and apoptosis was also demonstrated. It suggested that E6/E7 gene transfection into human salivary gland adenocarcinoma cells might induce clear squamous cell differentiation and contribute to study the pathogenesis of human salivary gland adenocarcinoma.

I. INTRODUCTION
 II. MATERIALS AND METHODS
  1. Cell Culture
  2. HPV DNA
  3. Transfection of HPV DNA into Cultured SGTCell Line
  4. Growth Curve and Apoptosis Index
  5. Western blot analysis
  6. Detection of HPV mRNA by RT-PCR
 III. RESULTS
  1. Growth Curve and Apoptosis Index
  2. Detection of HPV E6 and E7 mRNA
  3. mRNA Determinationof Involucrin andTransglutaminase 1
  4. Immunoslot blot Analysis of Involucrin andTransglutaminase 1
 V. DISCUSSION
 VI. REFERENCES

• 이종현(Department of Oral Pathology, The Oral Aging Research Center, Dental College, Dankook University) | Jong Hyun Lee
• 박경주(Department of Oral Pathology, The Oral Aging Research Center, Dental College, Dankook University) | Gyeong Ju Park
• 이종헌(Department of Oral Pathology, The Oral Aging Research Center, Dental College, Dankook University) | Chong Heon Lee correspondence