The antitumor effects of octyl gallate (OG) were investigated on FaDu human hypopharyngeal squamous carcinoma cells. At various concentrations, OG inhibited the proliferation of FaDu cells by suppressing cell cycle regulators and induced apoptosis by activating caspase 3 and its downstream poly (ADP-ribose) polymerase, thereby damaging DNA. Immunoblotting demonstrated that OG significantly suppressed the expression of integrin family proteins (integrin α4, αv, β3, β4), hindering cell adhesion. The reduced expression of integrins subsequently mediated the mitogenactivated protein kinase signaling pathway to stimulate the activation of extracellular signal-regulated kinases and c-jun N-terminal kinases, leading to apoptosis. Thus, OG demonstrated antitumor activity on hypopharyngeal squamous carcinoma cells by suppressing cell proliferation and inducing apoptosis.

Introduction
Materials and Methods
    1. Materials and reagents
    2. Cell culture
    3. Cell viability assay
    4. Western blotting
    5. Immunofluorescence imaging
    6. Statistical analysis
Results
    1. Octyl gallate inhibited FaDu cell proliferation
    2. OG’s effect on cell cycle regulators
    3. OG induced caspase-dependent apoptosis
    4. OG caused DNA damage on FaDu cells
    5. OG suppressed the expression of integrin familyproteins
    6. OG activated ERK and JNK in MAPK pathway
Discussion
Acknowledgements
Conflicts of Interest
References

• Hoon Yoo(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University) Correspondence to
• Trang NTK(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University)