Biological Effects of Hesperetin on Interleukin-6/Phosphorylated Signal Transducer and Activator of Transcription 3 Pathway Signaling in Prostate Cancer PC3 Cells.

BACKGROUND

Interleukin-6 (IL-6) is a multifunctional glycoprotein that regulates the growth of some tumors, including prostate carcinomas due to signal transducer and activator of transcription 3 (STAT3), extracellular signal-regulated kinases 1/2 (ERK1/2), and AKT signaling pathways. Hesperetin, as a flavanone, has several biological properties such as antitumor and anti-inflammatory.

OBJECTIVE

This study was carried out to evaluate the biological effects of hesperetin on the IL-6 gene expression and phosphorylated STAT3, AKT, and ERK1/2 signaling pathways in PC3 prostate cancer (PC) cells.

MATERIALS AND METHODS

In this study, we used real-time quantitative polymerase chain reaction (RT-qPCR) and ELISA to evaluate IL-6 gene expression and IL-6 protein secretion, respectively, in the treated PC3 cells with 0, 400, 450, and 500 μM of hesperetin. Cell survival studies were done by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after 48 h treatment with hesperetin, and cell apoptosis was determined by flow cytometry. The protein levels of activated signaling molecules (pSTAT3, pAKT, and pERK1/2) analyzed by immunoprecipitation technique.

RESULTS

Hesperetin-treated PC3 cells resulted in reduction of cell viability. Hesperetin led to the elevation of phosphorylated STAT3, ERK1/2, and AKT signaling proteins after 48 h in a dose-dependent manner as compared to the control cells. IL-6 gene expression, as well as protein level, significantly increased ( < 0.05) in a dose-dependent pattern in treated PC3 with hesperetin compared to the control cells. Further, hesperetin exposure resulted in the induction of cell cycle arrest at G0/G1 phase.

CONCLUSION

Hesperetin in PC3 cells led to elevation IL-6 gene expression, IL-6 protein secretion, pSTAT3, pERK1/2 and pAKT intracellular signaling proteins. Our results indicate that hesperetin treatment leads to the inhibition of cell proliferation and the induction of cell cycle arrest at the G1 phase. Hesperetin can be considered a potent agent which synchronizes and stops cell cycle at G0/G1 phase to apply suitable chemotherapeutic agents and radiotherapy in PC cells.

SUMMARY

This study evaluates biological effects of hesperetin on the cell cycle, interleukin-6 gene expression and some phosphorylated signaling pathways in PC3 prostate cancer cells. Hesperetin resulted in the inhibition of cell proliferation via inducing G0/G1 phase arrest in spite of the elevation of interleukin-6 gene expression and phosphorylated AKT, STAT3, and ERK1/2 intracellular signaling proteins. Therefore, hesperetin can be considered a potent agent which synchronizes and stop cell cycle at G0/G1 phase so that suitable chemotherapeutic agents can be applied in PC3 prostate cancer cells. PC: Prostate cancer, IL-6: Interleukin-6, STAT3: Signal transducer activator of transcription 3, ERK1/2: Extracellular signal-regulated kinases 1/2, IC50: Inhibitory concentration of 50%.