Effect of STAT3 siRNA-Induced Inhibition of STAT3 Gene Expression on the Growth and Apoptosis of Lewis Lung Cancer Cells

OBJECTIVE To determine the effect of short interference RNA (siRNA) against STAT3 induced inhibition of STAT3 gene expression and on the growth and apoptosis of Lewis lung cancer cells. METHODS pSilencer 2.1-U6 STAT3 siRNA against STAT3-mRNA was synthesized. Lewis lung cancer cells were divided into 3 groups: vehicle, plasmid, and STAT3 siRNA in which the cells were treated with RPMI-1640 culture media, or transfected with pSilencer empty vector, or pSilencer STAT3 siRNA. Semiquantitative RT-PCR and Western blot analysis of STAT3 gene expression in the cells was performed 72 h after transfection. MTT assay for cell proliferation, flow cytometry and DNA laddering electrophoresis were used for determination of cell proliferation and apoptosis. RESULTS STAT3 was markedly expressed at both the mRNA and protein levels in the cells treated with RPMI-1640 media or transfected with the plasmid vector, whereas STAT3 expression was significantly reduced in cells treated with STAT3 siRNA. These findings suggest that STAT3 siRNA effectively inhibited STAT3 expression. Transfection of the cells with STAT3 siRNA resulted in significant cellular growth inhibition and enhanced apoptosis. CONCLUSION Transfection of Lewis lung cancer cells with synthetic STAT3 siRNA resulted in effective inhibition of STAT3 gene expression at both protein and mRNA levels, leading to induced apoptosis and growth suppression.

Berberine inhibits androgen synthesis by interaction with aldo-keto reductase 1C3 in 22Rv1 prostate cancer cells

AIdo-keto reductase family 1 member C3 has recently been regarded as a potential therapeutic target in castrate-resistant prostate cancer. Herein, we investigated whether berberine delayed the progression of castrate-resistant prostate cancer by reducing androgen synthesis through the inhibition of Aldo-keto reductase family 1 member C3. Cell viability and cellular testosterone content were measured in prostate cancer cells. Aido-keto reductase family 1 member C3 mRNA and protein level were detected by RT-PCR and Western bolt analyses, respectively. Computer analysis with AutoDock Tools explored the molecular interaction of berberine with Aldo-keto reductase family 1 member C3. We found that berberine inhibited 22Rvl cells proliferation and decreased cellular testosterone formation in a dose-dependent manner. Berberine inhibited Aldo-keto reductase family I member C3 enzyme activity, rather than influenced mRNA and protein expressions. Molecular docking study demonstrated that berberine could enter the active center of Aldo-keto reductase family 1 member C3 and form π-π interaction with the amino-acid residue Phe306 and Phe311. In conclusion, the structural interaction of berberine with Aldo-keto reductase family 1 member C3 is attributed to the suppression of Aldo-keto reductase family I member C3 enzyme activity and the inhibition of 22Rvl prostate cancer cell growth by decreasing the intfacellular androgen synthesis. Our result provides the experimental basis for the design, research, and development of AKRlC3 inhibitors using berberine as the lead compound.