OBJECTIVETo study the mechanism of STAT3 antisense oligonucleotide (STAT3 AS-ON) in combination with DDP in the treatment of laryngeal cancer.

METHODSSTAT3 AS-ON, DDP, or STAT3 AS-ON + DDP was added into culture media. The expression and phosphorylation levels of STAT3 protein in Hep-2 cells were measured by Western Blot. The expression of Cyclin D1 and Bcl-xL was also detected by Western Blot. The cell proliferation was assayed by methyl thiazolyl tetrazolium (MTT). Flow cytometry was performed to analyze the cell cycle and apoptosis.

RESULTSSTAT3 was highly expressed and phosphorylated in Hep-2 cells. Transfection of STAT3 AS-ON suppressed the expression and phosphorylation levels of STAT3 protein. Forty-eight hours after transfection, the proliferation of Hep-2 cells was inhibited in a dose-dependent manner. Inhibitory effects appeared at 24 h after transfection of STAT3 AS-ON, and became more obvious after 36 h. Seventy-two hours after transfection, the rate of apoptosis in STAT3 AS-ON + DDP group, DDP group, STAT3 AS-ON group, STAT3 S-ON group, lipidosome group and control group was 32.9%, 13.5%, 28.1%, 3.2%, 2.4%, 1.8% respectively. After the treatment of Hep-2 cells with STAT3 AS-ON and DDP for 72 h, the ratio of G1 phase was up-regulated from 55.7% to 74.9%, while that of S phase was own-regulate from 33.6% to 6.9%.

CONCLUSIONSSTAT3 AS-ON and DDP could suppress the growth of laryngeal cancer cells and induce significant apoptosis of laryngeal cancer cells. Combined use of them had a synergic effect, obviously inhibiting the activation of STAT3 signaling transduction pathway of laryngeal cancer cells. Selective inhibition of specific signaling pathway may provide a new therapeutic approach for treating laryngeal cancers.