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The STAT3 inhibitor NSC 74859 is effective in hepatocellular cancers with disrupted TGF-beta signaling
1Cancer Genetics, Digestive Diseases, and Developmental Molecular Biology, Department of Surgery, Georgetown University, Washington, DC 20007, USA.
Abstract:
Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide, with few effective therapeutic options for advanced disease. At least 40% of HCCs are clonal, potentially arising from STAT3+, NANOG+ and OCT3/4+ liver progenitor/stem cell transformation, along with inactivation of transforming growth factor-beta (TGF-beta) signaling. Here we report significantly greater signal transducer and activator of transcription 3 (STAT3) and tyrosine phosphorylated STAT3 in human HCC tissues (P<0.0030 and P<0.0455, respectively) than in human normal liver. Further, in HCC cells with loss of response to TGF-beta, NSC 74859, a STAT3-specific inhibitor, markedly suppresses growth. In contrast, CD133(+) status did not affect the response to STAT3 inhibition: both CD133(+) Huh-7 cells and CD133(-) Huh-7 cells are equally sensitive to NSC 74859 treatment and STAT3 inhibition, with an IC(50) of 100 muM. Thus, the TGF-beta/beta2 spectrin (beta2SP) pathway may reflect a more functional 'stem/progenitor' state than CD133. Furthermore, NSC 74859 treatment of Huh-7 xenografts in nude mice significantly retarded tumor growth, with an effective dose of only 5 mg/kg. Moreover, NSC 74859 inhibited tyrosine phosphorylation of STAT3 in HCC cells in vivo. We conclude that inhibiting interleukin 6 (IL6)/STAT3 in HCCs with inactivation of the TGF-beta/beta2SP pathway is an effective approach in management of HCCs. Thus, IL6/STAT3, a major signaling pathway in HCC stem cell renewal and proliferation, can provide a novel approach to the treatment of specific HCCs.
Insights
Hepatocellular carcinoma (HCC) treatment can be improved by targeting the IL-6/STAT3 pathway, especially in tumors with inactivated TGF-beta signaling. This approach effectively inhibits cancer cell growth and proliferation.
Area of Science:
- Oncology
- Molecular Biology
- Hepatology
Background:
- Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality with limited therapeutic options for advanced stages.
- A subset of HCCs may originate from liver progenitor/stem cells, involving STAT3, NANOG, and OCT3/4 activation and TGF-beta signaling inactivation.
- STAT3 activation is implicated in HCC development and progression.
Purpose of the Study:
- To investigate the role of STAT3 signaling in HCC pathogenesis.
- To evaluate the efficacy of a STAT3-specific inhibitor (NSC 74859) in HCC models.
- To explore the relationship between TGF-beta signaling, stem cell markers, and response to STAT3 inhibition.
Main Methods:
- Analysis of STAT3 and phosphorylated STAT3 levels in human HCC tissues versus normal liver.
- In vitro studies using HCC cell lines with varying TGF-beta response and CD133 status, treated with NSC 74859.
- In vivo studies using HCC xenografts in nude mice treated with NSC 74859.
Main Results:
- Significantly elevated STAT3 and phosphorylated STAT3 were observed in HCC tissues compared to normal liver.
- NSC 74859 markedly suppressed HCC cell growth, particularly in cells with impaired TGF-beta signaling.
- CD133 status did not influence sensitivity to STAT3 inhibition, suggesting the TGF-beta/beta2SP pathway is a better indicator of stemness.
- NSC 74859 significantly inhibited tumor growth in vivo and reduced STAT3 phosphorylation.
Conclusions:
- Inhibition of the IL-6/STAT3 pathway is a promising therapeutic strategy for HCCs with inactivated TGF-beta/beta2SP signaling.
- The IL-6/STAT3 pathway plays a crucial role in HCC stem cell renewal and proliferation.
- Targeting IL-6/STAT3 offers a novel treatment approach for specific HCC subtypes.
