KOREASCHOLAR

be involved in the development of oral SCC. If we compare the morphologic features of NHOK to IHOK according to calcium concentration by TEM, IHOK have been gained wide acceptance as a model system for HPV-linked oral carcinogenesis. We already have established immortalized oral keratinocytes(IHOK) transfected by E6 and E7 gene. The purpose of this study were to examined the ultrastructural features of cultured NHOK, IHOK, and HN4 oral squamous cell carcinoma cell line, and to apply these results to oral carcinogenesis in the future. NHOK from healthy retromolar pad was primarily cultured at 37oC and 5% CO2. IHOK, and HN 4 cell line which were cultured under 0.15 and 1.2mM Ca++ of KBM bullet kit. For transmission electronmicroscopy(TEM), under preconfluency, and after 3 days of postconfluency under 1.2mM Ca++, cultured NHOK, IHOK, and HN4 cell line were immediately fixed in 2.0% glutaraldehyde in 0.1M cacodylate buffer(pH 7.4) at 4OC for 1h. The ultrathin sections were stained with uranyl acetate and lead citrate, and examined by TEM. The obtained results were as follows.

1. TEM of cultured NHOK under 1.2mM Ca++ showed increased tonofilaments, and vaculated ovoid cells with cornified envelope, while cultured IHOK showed prominent microvilli, unilateral desmosome in microvillus, and tonofilaments.
2. TEM of HN 4 cell line sowed numerous microvilli, increased N/C ratio, and lateral desmosome in microvilli under 0.15mm, while under 1.2mM well forming desmosomes.

From the aboving results, under high calcium cultured IHOK showed less tonofilaments than that of cultured NHOK, while cultured IHOK, and HN 4 cell lines showed more increased desmosomes under high calcium. It was suggested that the ultrastructural changes of cultured IHOK would be accepted as intermediate stage cells for studying oral carcinogenesis.

I. INTRODUCTION
 II. MATERIALS AND METHODS
  1. Culture conditions
  2. Transmission electronmicroscopy
 III. RESULTS
  1. Cultured NHOK
  2. Cultured IHOK
  3. HN 4 cell line
 IV. DISCUSSIONS
 REFERENCES

• 정연수(Department of Oral Pathology, Dental College, Dankook University) | Yeon Soo Chung
• 이종헌(Department of Oral Pathology, Dental College, Dankook University) | Chong Heon Lee correspondence