NS-398 induces apoptosis in human esophageal cancer cells through inhibition of NF-kappaB downstream regulation of cyclooxygenase-2.

ABSTRACT

Although non-steroidal anti-inflammatory drugs (NSAIDs) have been demonstrated to have cancer-preventive effects and induce apoptosis of cancer cells, the mechanism of their effects is not clearly known. We studied the mechanism in human esophageal cancer cell line TE13. The esophageal squamous cell carcinoma cell line TE-13 was cultured with NS-398 at different concentrations or for different times. Proliferation and apoptosis were measured by MTT reduction and flow cytometry. Prostaglandin F(1alpha) was determined with radioimmunoassay. Expression of COX-2 mRNA was measured by RT-PCR and COX-2 protein levels with Western blot analysis. Nuclear NF-kappaB and cytoplasmic IkappaB protein levels were determined by electrophoretic mobility shift assay and Western blot, respectively. NS-398 significantly inhibited cell proliferation and induced apoptosis at concentrations of 0.001, 0.01, 1, and 100 micromol/L. NS-398 dose-dependently decreased the levels of COX-2 mRNA, COX-2 protein, nuclear NF-kappaB protein and production of PGF(1alpha) and increased the cytoplasmic IkappaB protein. In conclusion, NS-398 inhibits the proliferation of, and induced apoptosis in, the cultured TE-13 SCC cell line. These changes correlate with a reduction in COX-2 mRNA and protein expression, prostaglandin synthesis, an inhibition of NF-kappaB nuclear translocation, and an increase in cytoplasmic IkappaB.