Adherent cells, such as those found in epithelial tissues, must be physically associated with extracellular matrix (ECM)components to survive. Though stimulation by growth factors is an essential factor in cell survival, normal cells also requires cell adhesion to ECM proteins. The cessation of these anchorage-mediated signals seems to be a common mechanism to physiolog ically t erminate t he l ife cycle of t hese c ells b y apoptosis. This form o f cell death has been termed anoikis.In cancer, resistance to anoikis of cancer cell is important in invasion and metastasis. The present study investigated the intracellular mechanism involved in anoikis, especially in cells treated with epigallocatechin- 3-gallate(EGCG). To induce anoikis, cell culture plates were coated with 10 ㎍/ml poly-HEMA. A549 lung adenocarcinoma cells were grown in RPMI 1640 medium with/without 10% fetal bovine serum, and then cells were replated on cell culture dishes coated with poly-HEMA in the presence or absence of serum. On the other hand, EGFR inhibitor, PI3K inhibitor, and EGCG were treated to the anoikis status cells, in order to evaluate the factors of anoikis. The result revealed that growth factors or loss of adhesion can increase phosphorylate Akt. In addition, lack of cell adhesion fails to activate pro-apoptotic factors directly. Activity of Erk kinase depends on not only EGFR signaling but also cell adhesion. Akt activation is mainly affected by EGCG whereas Raf-1 activation is controlled by the presence of cell contact. In addition, EGCG increased the level of NFkB, whereas phophroylated PTEN and total PTEN were not different. In this report,increase of NFkB was correlated with Akt phosphorylation, suggesting that EGCG can protect cells from detachment–induced cell death through Akt activation and subsequent NFkB

Green tea, derived from the plant Camellia sinensis, is one of the most common beverages consumed worldwide. Epigallocatechin-3-gallate (EGCG) is the most abundant and bioactive polyphenolic constituent in green tea. Understanding how intracellular signaling pathways respond to EGCG may provide a clue to the difference of cell responses and basis for usefulness of EGCG as a chemopreventive and/or chemotherapeutic agent. In the present study, we tried to check whether EGCG could be a useful agent in chemotherapeutic treatment of oral squamous carcinoma. Furthermore, we investigated which signaling pathway is involved in biologic activities of EGCG. EGCG induced the cell death of oral squamous carcinoma cells. Furthermore, it increased phosphorylation of Akt in serum-strarved oral squamous carcinoma cells. But, initial increase of Akt activation did not affect cell survival. Activities of Raf-1 and Erk showed inconsistent response to EGCG treatment, but Erk phosphorylation is consistent with Raf-1 activity in YD 10B cells. These changes of Raf-1 and Erk activity in EGCG treated cells were different depending on cell line type. Supposedly, the difference of cell component may affect the Raf-1 and Erk reactivity to EGCG treatment. Akt activation by EGCG is independent on activities of PDK1 and PTEN, and expression of bax and bcl-2 proteins were not changed by EGCG treatment. Therefore, EGCG treatment did not induce the apoptosis of YD 10B cell. On the other hand, vascular adhesion molecule (VCAM) was decreased by EGCG treatment, so it is possible that decrease of VCAM can play certain role in survival and/or cell death in EGCG treated cells