Objective: To examine the effect of exogenous zinc on enzymatic activity of tumor suppressor PTEN and underlying mechanisms.
Methods: Human airway epithelial cells (BEAS-2B) were employed as the in vitro model. Enzymatic activity of PTEN was measured using malachite green colorimetric assay and immunoblotting. Moreover, the activity of casein kinase-2 (CK-2), the upstream kinase of PTEN, was determined.
Results: Exposure of BEAS-2B cells to Zn2+ inhibited phosphatase activity of PTEN, as well as PTEN phosphorylation, indicative of PTEN activity (P < 0.05). Under the same experimental condition, Zn2+ stimulation resulted in significant reduction of CK-2 activity (P < 0.05). In addition, CK-2 was shown to induce PTEN phosphorylation (P < 0.05).
Conclusion: These results suggested that Zn2+ exposure might inhibit PTEN phosphatase activity through inhibition of CK-2 activity in human airway epithelial cells.