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Title: Paracrine IL-6 Signaling Confers Proliferation between Heterogeneous Inflammatory Breast Cancer Sub-Clones.
Austin Authors: Morrow, Riley J;Allam, Amr H;Yeo, Belinda ;Deb, Siddhartha;Murone, Carmel ;Lim, Elgene;Johnstone, Cameron N ;Ernst, Matthias 
Affiliation: Olivia Newton-John Cancer Research Institute
Anatomical Pathology
Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
School of Clinical Medicine, University of New South Wales, Randwick, NSW 2052, Australia
La Trobe University School of Cancer Medicine, 145 Studley Rd, Heidelberg, VIC 3084, Australia
Department of Clinical Pathology, University of Melbourne, Parkville, VIC 3010, Australia
Issue Date: 4-May-2022 2022
Publication information: Cancers 2022-05-04; 14(9): 2292.
Abstract: Inflammatory breast cancer (IBC) describes a highly aggressive form of breast cancer of diverse molecular subtypes and clonal heterogeneity across individual tumors. Accordingly, IBC is recognized by its clinical signs of inflammation, associated with expression of interleukin (IL)-6 and other inflammatory cytokines. Here, we investigate whether sub-clonal differences between expression of components of the IL-6 signaling cascade reveal a novel role for IL-6 to mediate a proliferative response in trans using two prototypical IBC cell lines. We find that SUM149 and SUM 190 cells faithfully replicate differential expression observed in a subset of human IBC specimens between IL-6, the activated form of the key downstream transcription factor STAT3, and of the HER2 receptor. Surprisingly, the high level of IL-6 produced by SUM149 cells activates STAT3 and stimulates proliferation in SUM190 cells, but not in SUM149 cells with low IL-6R expression. Importantly, SUM149 conditioned medium or co-culture with SUM149 cells induced growth of SUM190 cells, and this effect was abrogated by the IL-6R neutralizing antibody Tocilizumab. The results suggest a novel function for inter-clonal IL-6 signaling in IBC, whereby IL-6 promotes in trans proliferation of IL-6R and HER2-expressing responsive sub-clones and, therefore, may provide a vulnerability that can be exploited therapeutically by repurposing of a clinically approved antibody.
DOI: 10.3390/cancers14092292
ORCID: 0000-0003-2283-3970
Journal: Cancers
PubMed URL: 35565421
PubMed URL:
ISSN: 2072-6694
Type: Journal Article
Subjects: HER2
inflammatory breast cancer
Appears in Collections:Journal articles

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