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Lack of gp130 expression in hepatocytes attenuates tumor progression in the DEN model.

Hatting M, Spannbauer M, Peng J, Al Masaoudi M, Sellge G, Nevzorova YA, Gassler N, Liedtke C, Cubero FJ, Trautwein C - Cell Death Dis (2015)

Bottom Line: After acute DEN-induced liver injury we observed a reduction in the inflammatory response in gp130(Δhepa) animals as reflected by decreased levels of IL-6 and oncostatin M.However, gp130(Δhepa) livers revealed aberrant STAT5 activation and decreased levels of transforming growth factor-β (TGFβ), pSMAD2/3 and SMAD2, whereas phosphorylation of STAT3 at Tyr705 and Ser727 was absent.Gp130 deletion resulted in STAT3 inhibition but increased STAT5 activation and diminished TGF-dependent signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine III, University Hospital, RWTH Aachen, Aachen, Germany.

ABSTRACT
Chronic liver inflammation is a crucial event in the development and growth of hepatocellular carcinoma (HCC). Compelling evidence has shown that interleukin-6 (IL-6)/gp130-dependent signaling has a fundamental role in liver carcinogenesis. Thus, in the present study we aimed to investigate the role of gp130 in hepatocytes for the initiation and progression of HCC. Hepatocyte-specific gp130 knockout mice (gp130(Δhepa)) and control animals (gp130(f/f)) were treated with diethylnitrosamine (DEN). The role of gp130 for acute injury (0-144 h post treatment), tumor initiation (24 weeks) and progression (40 weeks) was analyzed. After acute DEN-induced liver injury we observed a reduction in the inflammatory response in gp130(Δhepa) animals as reflected by decreased levels of IL-6 and oncostatin M. The loss of gp130 slightly attenuated the initiation of HCC 24 weeks after DEN treatment. In contrast, 40 weeks after DEN treatment, male and female gp130(Δhepa) mice showed smaller tumors and reduced tumor burden, indicating a role for hepatocyte-specific gp130 expression during HCC progression. Oxidative stress and DNA damage were substantially and similarly increased by DEN in both gp130(f/f) and gp130(Δhepa) animals. However, gp130(Δhepa) livers revealed aberrant STAT5 activation and decreased levels of transforming growth factor-β (TGFβ), pSMAD2/3 and SMAD2, whereas phosphorylation of STAT3 at Tyr705 and Ser727 was absent. Our results indicate that gp130 deletion in hepatocytes reduces progression, but not HCC initiation in the DEN model. Gp130 deletion resulted in STAT3 inhibition but increased STAT5 activation and diminished TGF-dependent signaling. Hence, blocking gp130 in hepatocytes might be an interesting therapeutic target to inhibit the growth of HCC.

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Lack of gp130 in hepatocytes is associated with STAT5 activation 40 weeks after DEN treatment. Protein levels of pTyr705 STAT3 and pSer727 STAT3 (a) and pSTAT5 (b) were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. (c) RNA was extracted from total liver lysates after 40 weeks of DEN treatment and qRT-PCR for TGFβ was performed. (d) Protein levels of pSMAD2/3, SMAD2 and SMAD7 were determined by western blot in the same samples. Differences in MAPK/Ras signaling in gp130Δhepa compared with gp130f/f livers. (e) Protein levels of pAKT and pERK were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. Loading control was the same for pSTAT5 and pERK as both were developed on the same membrane. Graphs show mean±SEM (n=3; *P<0.05).
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fig7: Lack of gp130 in hepatocytes is associated with STAT5 activation 40 weeks after DEN treatment. Protein levels of pTyr705 STAT3 and pSer727 STAT3 (a) and pSTAT5 (b) were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. (c) RNA was extracted from total liver lysates after 40 weeks of DEN treatment and qRT-PCR for TGFβ was performed. (d) Protein levels of pSMAD2/3, SMAD2 and SMAD7 were determined by western blot in the same samples. Differences in MAPK/Ras signaling in gp130Δhepa compared with gp130f/f livers. (e) Protein levels of pAKT and pERK were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. Loading control was the same for pSTAT5 and pERK as both were developed on the same membrane. Graphs show mean±SEM (n=3; *P<0.05).

Mentions: In the mouse model, STAT3 was shown to be essential for DEN-induced carcinogenesis.25 Compelling molecular evidence has demonstrated a role for STAT3 in tumor initiation and progression.19, 26, 27 In line with these previous findings, STAT3 phosphorylation at Tyr705 and Ser727 was evident in gp130f/f livers 40 weeks after DEN injection. As expected, pSTAT3 expression was strongly inhibited in gp130Δhepa livers (Figure 7a, Supplementary Figure 7a and b). Noticeably, phosphorylation of serine 727 (Ser727) has been linked with neoplastic transformation of hepatocytes and also contributes to the maximal transcriptional activity of STAT3.28


Lack of gp130 expression in hepatocytes attenuates tumor progression in the DEN model.

Hatting M, Spannbauer M, Peng J, Al Masaoudi M, Sellge G, Nevzorova YA, Gassler N, Liedtke C, Cubero FJ, Trautwein C - Cell Death Dis (2015)

Lack of gp130 in hepatocytes is associated with STAT5 activation 40 weeks after DEN treatment. Protein levels of pTyr705 STAT3 and pSer727 STAT3 (a) and pSTAT5 (b) were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. (c) RNA was extracted from total liver lysates after 40 weeks of DEN treatment and qRT-PCR for TGFβ was performed. (d) Protein levels of pSMAD2/3, SMAD2 and SMAD7 were determined by western blot in the same samples. Differences in MAPK/Ras signaling in gp130Δhepa compared with gp130f/f livers. (e) Protein levels of pAKT and pERK were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. Loading control was the same for pSTAT5 and pERK as both were developed on the same membrane. Graphs show mean±SEM (n=3; *P<0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4385909&req=5

fig7: Lack of gp130 in hepatocytes is associated with STAT5 activation 40 weeks after DEN treatment. Protein levels of pTyr705 STAT3 and pSer727 STAT3 (a) and pSTAT5 (b) were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. (c) RNA was extracted from total liver lysates after 40 weeks of DEN treatment and qRT-PCR for TGFβ was performed. (d) Protein levels of pSMAD2/3, SMAD2 and SMAD7 were determined by western blot in the same samples. Differences in MAPK/Ras signaling in gp130Δhepa compared with gp130f/f livers. (e) Protein levels of pAKT and pERK were determined by western blot of total liver protein lysates of 40 weeks-DEN-treated gp130f/f and gp130Δhepa animals. As controls, untreated animals were used. GAPDH was used as loading control. Loading control was the same for pSTAT5 and pERK as both were developed on the same membrane. Graphs show mean±SEM (n=3; *P<0.05).
Mentions: In the mouse model, STAT3 was shown to be essential for DEN-induced carcinogenesis.25 Compelling molecular evidence has demonstrated a role for STAT3 in tumor initiation and progression.19, 26, 27 In line with these previous findings, STAT3 phosphorylation at Tyr705 and Ser727 was evident in gp130f/f livers 40 weeks after DEN injection. As expected, pSTAT3 expression was strongly inhibited in gp130Δhepa livers (Figure 7a, Supplementary Figure 7a and b). Noticeably, phosphorylation of serine 727 (Ser727) has been linked with neoplastic transformation of hepatocytes and also contributes to the maximal transcriptional activity of STAT3.28

Bottom Line: After acute DEN-induced liver injury we observed a reduction in the inflammatory response in gp130(Δhepa) animals as reflected by decreased levels of IL-6 and oncostatin M.However, gp130(Δhepa) livers revealed aberrant STAT5 activation and decreased levels of transforming growth factor-β (TGFβ), pSMAD2/3 and SMAD2, whereas phosphorylation of STAT3 at Tyr705 and Ser727 was absent.Gp130 deletion resulted in STAT3 inhibition but increased STAT5 activation and diminished TGF-dependent signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine III, University Hospital, RWTH Aachen, Aachen, Germany.

ABSTRACT
Chronic liver inflammation is a crucial event in the development and growth of hepatocellular carcinoma (HCC). Compelling evidence has shown that interleukin-6 (IL-6)/gp130-dependent signaling has a fundamental role in liver carcinogenesis. Thus, in the present study we aimed to investigate the role of gp130 in hepatocytes for the initiation and progression of HCC. Hepatocyte-specific gp130 knockout mice (gp130(Δhepa)) and control animals (gp130(f/f)) were treated with diethylnitrosamine (DEN). The role of gp130 for acute injury (0-144 h post treatment), tumor initiation (24 weeks) and progression (40 weeks) was analyzed. After acute DEN-induced liver injury we observed a reduction in the inflammatory response in gp130(Δhepa) animals as reflected by decreased levels of IL-6 and oncostatin M. The loss of gp130 slightly attenuated the initiation of HCC 24 weeks after DEN treatment. In contrast, 40 weeks after DEN treatment, male and female gp130(Δhepa) mice showed smaller tumors and reduced tumor burden, indicating a role for hepatocyte-specific gp130 expression during HCC progression. Oxidative stress and DNA damage were substantially and similarly increased by DEN in both gp130(f/f) and gp130(Δhepa) animals. However, gp130(Δhepa) livers revealed aberrant STAT5 activation and decreased levels of transforming growth factor-β (TGFβ), pSMAD2/3 and SMAD2, whereas phosphorylation of STAT3 at Tyr705 and Ser727 was absent. Our results indicate that gp130 deletion in hepatocytes reduces progression, but not HCC initiation in the DEN model. Gp130 deletion resulted in STAT3 inhibition but increased STAT5 activation and diminished TGF-dependent signaling. Hence, blocking gp130 in hepatocytes might be an interesting therapeutic target to inhibit the growth of HCC.

Show MeSH
Related in: MedlinePlus