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Gender Disparity in Liver Cancer Due to Sex Differences in MyD88-Dependent IL-6 Production

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Science  06 Jul 2007:
Vol. 317, Issue 5834, pp. 121-124
DOI: 10.1126/science.1140485
  • Fig. 1.

    Differential IL-6 production after chemically induced liver injury. (A) Concentration of IL-6 in serum of male and female WT mice after injection of DEN (100 mg per kg of body weight; n =3 mice per time point). (B) IL-6 mRNA levels in livers of male, female, or ovariectomized (OVX; ovariectomy was done 2 weeks before DEN administration) female mice 4 hours after DEN injection. E2 (50 μg/kg)incornoilwas injected intraperitoneally 2 hours before DEN was administered. (C) Male B6 mice (n =3) were injected with ERα-specific agonist propyl-pyrazole-trisphenol (PPT; 5 μg/kg in corn oil) 2 hours before DEN injection, and serum IL-6 was measured at the indicated times after DEN injection. Results in (A) to (C) are means ± SE. Asterisks indicate a significant (P < 0.05; Student's t test) difference relative to WT male mice.

  • Fig. 2.

    Lower incidence of HCC tumors and longer survival of IL-6–/– mice. (A)Livers of 8-month-old DEN-treated mice. Multiple HCCs are seen only in WT male liver. (B) Incidence of HCC (> 0.5 mm) in WT male (n = 14), WT female (n = 13), IL-6–/– male (n = 14), and IL-6–/– female (n = 15) mice 8 months after DEN (25 mg/kg) injection. Asterisks indicate significant (P < 0.05; Student's t test) differences relative to WT male mice. (C) Survival curves of WT and IL-6–/– mice injected with DEN (25 mg/kg) at 15 days of age (P = 0.0006; log-rank test for significance).

  • Fig. 3.

    Influence of gender and IL-6 on hepatic injury and compensatory proliferation. (A)Male WT or IL-6–/– mice (n = 3) were given DEN (100 mg/kg), and ALT (alanine aminotransferase) in serum was measured. (B) Livers of male WT or IL-6–/– mice (n = 3) were assessed for apoptosis by TUNEL (terminal deoxynucleotidyl transferase– mediated dUTP nick-end labeling) staining after DEN injection. (C) Hepatocyte proliferation in livers of DEN-injected male WT or IL-6–/– mice (n = 3) was assessed by injecting mice with bromodeoxyrudine (BrdU) (1 mg per mouse) 2 hours before the liver was removed. BrdU-positive cells were identified by immunostaining. (D) Serum ALT was measured 48 hours after DEN injection (n = 3 per group). OVX: female mice ovariectomized 2 weeks before DEN administration. E2 (50 μg/kg) in corn oil was injected 2 hours before DEN. Similar studies assessing differences between male and female mice (n = 3) were done for apoptosis (E) and proliferation (F). (G) Six-week-old male B6 mice (n = 3) were given E2 or vehicle (corn oil) 2 hours before DEN injection. Recombinant IL-6 (10 μg) or sham buffer (phosphate-buffered saline) was given subcutaneously at the time of DEN administration. Serum ALT was measured 48 hours later. (H) Male ERα–/– and ERβ–/– mice and littermate heterozygote controls (n = 3) were injected with E2 (50 μg) in corn oil or vehicle 2 hours before DEN injection, and serum ALT was measured 50 hours later. (I)Malemice(n = 3 per point) were injected with PPT (5 mg/kg in corn oil) or vehicle 2 hours before DEN injection, and serum ALT was measured 50 hours later. All results for (A) to (I) are means ± SE, and asterisks indicate P < 0.05 (Student's t test). (J) Cells from livers of male, female, and IL-6–/– mice were lysed at the indicated times after DEN injection. STAT3 and JNK activation, and IκBα degradation, were assessed by separating with SDS–polyacrylamide gel electrophoresis and immunoblotting with antibodies to the indicated proteins. Phosphorylation (P) of STAT3 and JNK indicates activation. Phospho-STAT3 and STAT3 were from one gel, as were Phospho-JNK and JNK1/2, and IκBα and actin.

  • Fig. 4.

    Requirement of MyD88 for IL-6 production, injury, and hepatocarcinogenesis after DEN treatment. (A)Accumulation of IL-6 mRNA was measured by real-time polymerase chain reaction in KCs from male WT, IKKβ–/–, or MyD88–/– mice (n =3 experiments per time point) after incubation with LPS (10 ng/ml) or necrotic debris prepared by cycles of freezethawing of primary hepatocytes. Where indicated, cells were incubated with E2 (10 ng/ml) 30 min before stimulation. (B and C) Male WT and MyD88–/– mice were injected with DEN, and liver IL-6 mRNA (B) or serum ALT (C) was measured. (D and E) Number of HCCs(D) and sizes (E) in livers of WT and MyD88–/– male mice 8 months after DEN (25 mg/kg) administration. Results in (A) to (E) are means ± SE. Asterisks indicate a significant (P <0.05; Student's t test) difference relative to WT males.

Additional Files


  • Gender Disparity in Liver Cancer Due to Sex Differences in MyD88- Dependent IL-6 Production
    Willscott E. Naugler, Toshiharu Sakurai, Sunhwa Kim, Shin Maeda, KyoungHyun Kim, Ahmed M. Elsharkawy, Michael Karin

    Supporting Online Material

    This supplement contains:
    Materials and Methods
    Figs. S1 to S8
    References

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