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Hedyotis diffusa Willd. extract suppresses proliferation and induces apoptosis via IL-6-inducible STAT3 pathway inactivation in human colorectal cancer cells.

Lin J, Li Q, Chen H, Lin H, Lai Z, Peng J - Oncol Lett (2015)

Bottom Line: Pretreatment of HT-29 cells with IL-6 led to an increase in cell viability, colony formation and phosphorylated STAT3 (p-STAT3) expression.Treatment of these cells with EEHDW prior to IL-6 stimulation resulted in a significant reduction in the IL-6-induced phosphorylation of STAT3.In addition, EEHDW treatment significantly reduced the mRNA expression levels of cyclin D1, cyclin-dependent kinase 4 and B-cell lymphoma-2 (Bcl-2), and upregulated the expression levels of Bcl-2-associated X protein (P<0.05), which are important target genes of the IL-6/STAT3 pathway.

View Article: PubMed Central - PubMed

Affiliation: Academy of Integrative Medicine Biomedical Research Center, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China ; Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.

ABSTRACT

Recent studies have indicated that the inflammatory microenvironment plays a significant role in colorectal cancer (CRC). The interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway mediates the proliferative and anti-apoptotic activities required for oncogenesis under inflammatory conditions; thus, suppressing tumor growth by targeting the IL-6/STAT3 pathway is a promising therapeutic strategy for CRC. Our previous study reported that the ethanol extract obtained from Hedyotis diffusa Willd. (EEHDW) can induce apoptosis, and inhibit the proliferation of colon cancer cells and tumor angiogenesis by modulating various signaling pathways; however, less is known regarding the activity of EEHDW in a cancer-promoting inflammatory environment. Therefore, the present study investigated whether EEHDW inhibits the growth of the CRC HT-29 cell line via the IL-6/STAT3 signaling pathway. Pretreatment of HT-29 cells with IL-6 led to an increase in cell viability, colony formation and phosphorylated STAT3 (p-STAT3) expression. Treatment of these cells with EEHDW prior to IL-6 stimulation resulted in a significant reduction in the IL-6-induced phosphorylation of STAT3. In addition, EEHDW treatment significantly reduced the mRNA expression levels of cyclin D1, cyclin-dependent kinase 4 and B-cell lymphoma-2 (Bcl-2), and upregulated the expression levels of Bcl-2-associated X protein (P<0.05), which are important target genes of the IL-6/STAT3 pathway. These findings strongly indicated that EEHDW suppresses tumor cell growth and induces the apoptosis of human CRC cells via inactivation of the IL-6/STAT3 signaling pathway.

No MeSH data available.


Related in: MedlinePlus

EEHDW treatment inhibits IL-6-mediated STAT3 phosphorylation in HT-29 cells. The HT-29 cells were pretreated with the indicated doses of EEHDW for 1 h prior to IL-6 stimulation for 15 min. (A) Western blot of STAT3 and p-STAT3 in HT-29 cells treated with EEHDW. β-actin served as the loading control (n=3). (B) Densitometric analysis. The data were normalized to the mean protein expression of untreated control. The columns represent the mean of three experiments, and the bars represent the standard deviation from the mean. *P<0.01 vs. controls; #P<0.05 vs. cells treated with IL-6 alone. pSTAT3, phosphorylated signal transducer and activator of transcription; IL-6, interleukin-6; EEHDW, ethanol extract obtained from Hedyotis diffusa Willd.
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f6-ol-09-04-1962: EEHDW treatment inhibits IL-6-mediated STAT3 phosphorylation in HT-29 cells. The HT-29 cells were pretreated with the indicated doses of EEHDW for 1 h prior to IL-6 stimulation for 15 min. (A) Western blot of STAT3 and p-STAT3 in HT-29 cells treated with EEHDW. β-actin served as the loading control (n=3). (B) Densitometric analysis. The data were normalized to the mean protein expression of untreated control. The columns represent the mean of three experiments, and the bars represent the standard deviation from the mean. *P<0.01 vs. controls; #P<0.05 vs. cells treated with IL-6 alone. pSTAT3, phosphorylated signal transducer and activator of transcription; IL-6, interleukin-6; EEHDW, ethanol extract obtained from Hedyotis diffusa Willd.

Mentions: Numerous human cancer cell lines, including HT-29, do not constitutively express p-STAT3 in vitro, however, previous studies have demonstrated that IL-6 can stimulate STAT3 activation in HT-29 cells (22). Thus, the present study stimulated STAT3 activation by administering IL-6 to the HT-29 cells, and western blot analysis of the cell lysates was performed to determine the phosphorylation levels of STAT3 at Tyr705. Stimulation of the HT-29 cells with IL-6 (10 ng/ml) significantly increased the protein expression levels of p-STAT3, however, phosphorylation was significantly inhibited by EEHDW in a dose-dependent manner (P<0.05) (Fig. 6). By contrast, the protein expression level of non-phosphorylated STAT3 remained unchanged following treatment with IL-6 and/or EEHDW.


Hedyotis diffusa Willd. extract suppresses proliferation and induces apoptosis via IL-6-inducible STAT3 pathway inactivation in human colorectal cancer cells.

Lin J, Li Q, Chen H, Lin H, Lai Z, Peng J - Oncol Lett (2015)

EEHDW treatment inhibits IL-6-mediated STAT3 phosphorylation in HT-29 cells. The HT-29 cells were pretreated with the indicated doses of EEHDW for 1 h prior to IL-6 stimulation for 15 min. (A) Western blot of STAT3 and p-STAT3 in HT-29 cells treated with EEHDW. β-actin served as the loading control (n=3). (B) Densitometric analysis. The data were normalized to the mean protein expression of untreated control. The columns represent the mean of three experiments, and the bars represent the standard deviation from the mean. *P<0.01 vs. controls; #P<0.05 vs. cells treated with IL-6 alone. pSTAT3, phosphorylated signal transducer and activator of transcription; IL-6, interleukin-6; EEHDW, ethanol extract obtained from Hedyotis diffusa Willd.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4356405&req=5

f6-ol-09-04-1962: EEHDW treatment inhibits IL-6-mediated STAT3 phosphorylation in HT-29 cells. The HT-29 cells were pretreated with the indicated doses of EEHDW for 1 h prior to IL-6 stimulation for 15 min. (A) Western blot of STAT3 and p-STAT3 in HT-29 cells treated with EEHDW. β-actin served as the loading control (n=3). (B) Densitometric analysis. The data were normalized to the mean protein expression of untreated control. The columns represent the mean of three experiments, and the bars represent the standard deviation from the mean. *P<0.01 vs. controls; #P<0.05 vs. cells treated with IL-6 alone. pSTAT3, phosphorylated signal transducer and activator of transcription; IL-6, interleukin-6; EEHDW, ethanol extract obtained from Hedyotis diffusa Willd.
Mentions: Numerous human cancer cell lines, including HT-29, do not constitutively express p-STAT3 in vitro, however, previous studies have demonstrated that IL-6 can stimulate STAT3 activation in HT-29 cells (22). Thus, the present study stimulated STAT3 activation by administering IL-6 to the HT-29 cells, and western blot analysis of the cell lysates was performed to determine the phosphorylation levels of STAT3 at Tyr705. Stimulation of the HT-29 cells with IL-6 (10 ng/ml) significantly increased the protein expression levels of p-STAT3, however, phosphorylation was significantly inhibited by EEHDW in a dose-dependent manner (P<0.05) (Fig. 6). By contrast, the protein expression level of non-phosphorylated STAT3 remained unchanged following treatment with IL-6 and/or EEHDW.

Bottom Line: Pretreatment of HT-29 cells with IL-6 led to an increase in cell viability, colony formation and phosphorylated STAT3 (p-STAT3) expression.Treatment of these cells with EEHDW prior to IL-6 stimulation resulted in a significant reduction in the IL-6-induced phosphorylation of STAT3.In addition, EEHDW treatment significantly reduced the mRNA expression levels of cyclin D1, cyclin-dependent kinase 4 and B-cell lymphoma-2 (Bcl-2), and upregulated the expression levels of Bcl-2-associated X protein (P<0.05), which are important target genes of the IL-6/STAT3 pathway.

View Article: PubMed Central - PubMed

Affiliation: Academy of Integrative Medicine Biomedical Research Center, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China ; Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.

ABSTRACT

Recent studies have indicated that the inflammatory microenvironment plays a significant role in colorectal cancer (CRC). The interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway mediates the proliferative and anti-apoptotic activities required for oncogenesis under inflammatory conditions; thus, suppressing tumor growth by targeting the IL-6/STAT3 pathway is a promising therapeutic strategy for CRC. Our previous study reported that the ethanol extract obtained from Hedyotis diffusa Willd. (EEHDW) can induce apoptosis, and inhibit the proliferation of colon cancer cells and tumor angiogenesis by modulating various signaling pathways; however, less is known regarding the activity of EEHDW in a cancer-promoting inflammatory environment. Therefore, the present study investigated whether EEHDW inhibits the growth of the CRC HT-29 cell line via the IL-6/STAT3 signaling pathway. Pretreatment of HT-29 cells with IL-6 led to an increase in cell viability, colony formation and phosphorylated STAT3 (p-STAT3) expression. Treatment of these cells with EEHDW prior to IL-6 stimulation resulted in a significant reduction in the IL-6-induced phosphorylation of STAT3. In addition, EEHDW treatment significantly reduced the mRNA expression levels of cyclin D1, cyclin-dependent kinase 4 and B-cell lymphoma-2 (Bcl-2), and upregulated the expression levels of Bcl-2-associated X protein (P<0.05), which are important target genes of the IL-6/STAT3 pathway. These findings strongly indicated that EEHDW suppresses tumor cell growth and induces the apoptosis of human CRC cells via inactivation of the IL-6/STAT3 signaling pathway.

No MeSH data available.


Related in: MedlinePlus