Wei LH, Kuo ML, Chen CA, Chou CH, Lai KB, Lee CN, Hsieh CY. Interleukin-6 promotes cervical tumor growth by VEGF-dependent angiogenesis via a STAT3 pathway.
Oncogene 2003;
22:1517-27. [PMID:
12629515 DOI:
10.1038/sj.onc.1206226]
[Citation(s) in RCA: 398] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Interleukin-6 (IL-6) has received particular attention in the pathogenesis of cervical cancer, although the underlying mechanism remains elusive. This study revealed that IL-6 promotes in vivo tumor growth of human cervical cancer C33A cells, but does not substantially alter their in vitro growth kinetics. The in vivo angiogenic assays showed that IL-6 increases angiogenic activity in human cervical cancer cells, an effect that is specifically associated with upregulation of vascular endothelial growth factor (VEGF). Also, using anti-VEGF antibody to block VEGF function significantly inhibited IL-6-mediated angiogenesis and tumor growth in nude mice, strongly supporting the critical role of VEGF in the IL-6-mediated cervical tumorigenesis. Accordingly, the signaling pathway downstream of IL-6/IL-6R responsible for the regulation of VEGF was investigated. Notably, pharmacological inhibition of PI3-K or MAPK failed to inhibit IL-6-mediated transcriptional upregulation of VEGF. Meanwhile, blocking STAT3 pathway with dominant-negative mutant STAT3D effectively abolished IL-6-induced VEGF mRNA. In transient transfections, a luciferase reporter construct containing the full-length 1.5-kb VEGF promoter or a 1.2-kb fragment lacking the known hypoxic-response element also exhibited the same degree of response to IL-6. Additionally, transient transfection of STAT3D downregulated the 1.2-kb VEGF promoter luciferase reporter stimulated by IL-6. Based on the above phenomenon combined with the concomitant increased tumor expression of IL-6 and VEGF in cervical cancer tissues, we conclude that IL-6 may promote cervical tumorigenesis by activating VEGF-mediated angiogenesis via a STAT3 pathway.
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