Inhibition of STAT3 expression by siRNA suppresses growth and induces apoptosis in laryngeal cancer cells

Abstract

Aim: To determine the inhibitory effect of the synthetic STAT3 siRNA on the expression of STAT3 gene in human laryngeal cancer cell lines Hep2 and to investigate the effect of STAT3 siRNA on growth and apoptosis in Hep2 cells. Methods: A pair of DNA templates coding siRNA against STAT3-mRNA was synthesized to reconstruct plasmid of pSilencer1.0-U6 siRNA-STAT3. Hep2 cells were transfected with RPMI-1640 media (untreated), plasmid (empty), and STAT3 siRNA, respectively. Northern blot and Western blot analysis of STAT3 and pTyr-STAT3 expression in Hep2 cells and Western blot analysis of Bcl-2 expression in the Hep2 cell was performed 72 h after transfection. MTT, flow cytometry, and AO/EB assay were used for determination of cells proliferation and apoptosis in Hep2 cells. Results: pTyr-STAT3 was markedly expressed in untreated Hep2 cells and the vector-treated Hep2 cells, whereas pTyr-STAT3 expression was significantly reduced in STAT3 siRNA-transfected Hep2 cells, indicating that STAT3 siRNA inhibited the activity of STAT3. Transfection of Hep2 cells with STAT3 siRNA significantly inhibited STAT3 expression at both mRNA and protein level in Hep2 cells and the inhibition was characterized by time-dependent transfection. Treatment of Hep2 cells with STAT3 siRNA resulted in dose-dependent growth inhibition of Hep2, this significantly increased apoptotic cell rate, and decreased Bcl-2 expression level in Hep2 cells. STAT3 siRNA had an effect on induction of either early or late stage apoptosis. Conclusion: This study demonstrates that STAT3 siRNA effectively inhibits STAT3 gene expression in Hep2 cells leading to growth suppression and induction of apoptosis in Hep2 cells. The use of siRNA technique may provide a novel therapeutic approach to treat laryngeal cancer and other malignant tumors expressing constitutively activated STAT3.

Inhibition of tumor growth and induction of apoptosis in prostate cancer cell lines by overexpression of tissue inhibitor of matrix metalloproteinase-3

“…Late apoptotic cells were stained orange and showed condensed and fragmented nuclei. 23 These results suggested that TIMP-3 had not only an effect on induction of early apoptosis, but also late apoptosis in these cells. Moreover, flow cytometry analysis showed that the rate of apoptosis in the TIMP-3 overexpression group was significantly higher than that in the untreated PC-3M cells and the vector-treated PC-3M cells.…”

“…31 In China, most prostate cancers are diagnosed in an advanced stage when there is little chance of cure by radical prostatectomy. 23,[32][33][34] Thus, it has become important to develop new treatment strategies for metastasic prostate cancer. 35 Invasion and metastasis of tumors cells, including prostate cancer cells, is dependent on their ability to destroy the extracellular matrix.…”

C/EBP expression in ALK-positive anaplastic large cell lymphomas is required for cell proliferation and is induced by the STAT3 signaling pathway

“…Oligonucleotides containing short hairpin RNA (shRNA) sequences for the target genes of interest were used: C/EBPβ-C1 sense -5'-GAAGACCGTGGACAAGCAC-3', 13 STAT3-Gh1 sense -5'-GCAGCAGCTGA ACAACATGT-3', 14 mammalian target of rapamycin (mTOR) sense -5'-GGAGTCTACTCGCTTC-TAT-3'; and AKT sense -5'-GGGCACTTTCGGCAAGG TG-3'. 15 Oligonucleotides were cloned into the H1 promoter driven vector pSuper (Oligoengine, Seattle, WA, USA) as described previously.…”

RNA Interference as a Plausible Anticancer Therapeutic Tool

“…RNAi specific to STAT3 resulted in inhibition of DU-145 prostate cancer cell line by inducing apoptotic cell death (Lee et al, 2004). STAT3 siRNA inhibited the growth of Hep2 human laryngeal cancer cell line, resulting in apoptosis and down regulation of Bcl-2 expression (Gao et al, 2005).…”