Abstract
Hormone-resistant (HR) prostate cancers are highly aggressive and respond poorly to treatment. A better understanding of the molecular mechanisms involved in HR should lead to more rational approaches to therapy. The role of IL-6/STAT3 signaling in the transition of HR with aggressive tumor behavior and its possible link with myeloid-derived suppressor cells (MDSCs) were identified. In the present study, murine prostate cancer cell line (TRAMP-C1) and a hormone-resistant cell sub-line (TRAMP-HR) were used. Changes in tumor growth, invasion ability, and the responsible pathway were investigated in vitro and in vivo. We also examined the role of IL-6 in HR tumor progression and the recruitment of MDSCs. As seen in both in vitro and in vivo experiments, HR had aggressive tumor growth compared to TRAMP-C1. From mRNA and protein analysis, a higher expression of IL-6 associated with a more activated STAT3 was noted in HR tumor. When IL-6 signaling in prostate cancer was blocked, aggressive tumor behavior could be overcome. The underlying changes included decreased cell proliferation, less epithelial–mesenchymal transition, and decreased STAT3 activation. In addition to tumor progression, circulating IL-6 levels were significantly correlated with MDSC recruitment in vivo. Inhibition of IL-6 abrogated the recruitment of MDSCs in tumor- bearing mice, associated with slower tumor growth and attenuated angiogenesis. In conclusion, altered IL-6/STAT3 signaling is crucial in HR transition, aggressive behavior, and MDSC recruitment. These findings provide evidence for therapeutically targeting IL-6 signaling in prostate cancer.
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Abbreviations
- HR:
-
Hormone-resistant
- HS:
-
Hormone-sensitive
- MDSCs:
-
Myeloid-derived suppressor cells
- AR:
-
Androgen receptor
- EMT:
-
Epithelial–mesenchymal transition
- VEGF:
-
Vascular endothelial growth factor
- WBI:
-
Whole-body irradiation
- LI:
-
Local irradiation
- RT:
-
Irradiation
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Acknowledgments
The study was supported by grants from the National Science Council (grants 97-2314-B-182A-079-MY3) and CMRPG 290041.
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There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
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Wu, CT., Hsieh, CC., Lin, CC. et al. Significance of IL-6 in the transition of hormone-resistant prostate cancer and the induction of myeloid-derived suppressor cells. J Mol Med 90, 1343–1355 (2012). https://doi.org/10.1007/s00109-012-0916-x
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DOI: https://doi.org/10.1007/s00109-012-0916-x