Cigarette Smoke Extract Increases Invasion in Ca9-22 Gingival Cancer Cells

Objectives: Oral squamous cell carcinoma is a common disease affecting around thirty thousand people in the United States each year. One of the major causes of this is tobacco smoke. The effects of second hand smoke in the development of gingival carcinoma are limited and still need to be investigated. Our objective was to determine the role and mechanism of Cigarette Smoke Extract (CSE) in oral squamous cell carcinoma invasion.
Methods: Ca9-22 cells were cultured in RPMI supplemented with 10% of fetal calf serum. Cells were cultured in the presence or absence of CSE. Real Time cell invasions were performed and cultured cells were lysed for western blot analysis.
Results: Treatment of cells with CSE showed: 1) increased invasion with 0.05%, 0.1%, 0.2%, and 0.5% CSE treatment (1.8-fold, 7.6-fold, 6.6-fold, and 8.4-fold respectively; p<0.0002), 2) RAGE receptor activation (6.8-fold; p<0.05), 3) no change in ERK activation, and 4) increase in AKT activation (3.6-fold; p<0.05).
Conclusions: We conclude that CSE is able to increase invasion of oral squamous cell carcinoma cells. We also conclude that this increase correlates with the activation of the AKT pathway. These results could be useful in providing avenues that could explain the role of second hand smoke in the development of oral squamous cell carcinoma.