Epigallocatechin-3-gallate (EGCG) and theaflavins (TF) are polyphenols included in green and black teas, respectively. Both green and black teas have been studied for their potential health benefits for cancer. Hypoxia-inducible factor (HIF) has been implicated multiple physiological and pathophysiological pathways, particularly, oncogenesis. But, the molecular pathways that govern the cell response to EGCG are not fully elucidated. The present study investigated the intracellular mechanism in oral squamous cell carcinoma (OSCC) cells treated with EGCG, focusing on HIF-1 expression and its effect on epithelial phenotype. EGCG decreased phosphorylated Raf-1 protein in YD 8 OSCC cell, but B-raf protein was not affected at all by EGCG and TF. In addition, we here found that EGCG regulated HIF-1α expression independent of Raf-1 protein. Taken together with our previous result, the result imply that EGCG is attributed to the HIF-1α expression via Raf/MEK/ERK pathway, and the HIF-1α expression is associated with the change of epithelial phenotype in OSCC cell.

I. INTRODUCTION
 II. MATERIALS AND METHODS
  1. Cell culture
  2. Chemicals
  3. Western Blot Analysis
 III. RESULTS
  1. EGCG decreases Raf-1 protein in dosedependentmanner
  2. T F s show no effect on the level of Raf-1 inthe presence of serum while EGCG downregulates Raf-1 protein
  3. EGCG decreases Raf-1 protein not throughautophagic pathway but through proteosomaldegradation
  4. EGCG promotes HIF-1α accumulation
  5. HIF-1α is involved in the change of epithelialphenotype of OSCC cells
 IV. DISCUSSION
 V. REFERENCES

• 정성희(Department of Dental Hygiene, Shingu University) | Sung Hee Jeong correspondence