The JAK2/STAT3 signaling pathway is required for growth of CD44+CD24– stem cell–like breast cancer cells in human tumors
Lauren L.C. Marotta, Vanessa Almendro, Andriy Marusyk, Michail Shipitsin, Janina Schemme, Sarah R. Walker, Noga Bloushtain-Qimron, Jessica J. Kim, Sibgat A. Choudhury, Reo Maruyama, Zhenhua Wu, Mithat Gönen, Laura A. Mulvey, Marina O. Bessarabova, Sung Jin Huh, Serena J. Silver, So Young Kim, So Yeon Park, Hee Eun Lee, Karen S. Anderson, Andrea L. Richardson, Tatiana Nikolskaya, Yuri Nikolsky, X. Shirley Liu, David E. Root, William C. Hahn, David A. Frank, Kornelia Polyak
Lauren L.C. Marotta, Vanessa Almendro, Andriy Marusyk, Michail Shipitsin, Janina Schemme, Sarah R. Walker, Noga Bloushtain-Qimron, Jessica J. Kim, Sibgat A. Choudhury, Reo Maruyama, Zhenhua Wu, Mithat Gönen, Laura A. Mulvey, Marina O. Bessarabova, Sung Jin Huh, Serena J. Silver, So Young Kim, So Yeon Park, Hee Eun Lee, Karen S. Anderson, Andrea L. Richardson, Tatiana Nikolskaya, Yuri Nikolsky, X. Shirley Liu, David E. Root, William C. Hahn, David A. Frank, Kornelia Polyak
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Research Article

The JAK2/STAT3 signaling pathway is required for growth of CD44+CD24– stem cell–like breast cancer cells in human tumors

Abstract

Intratumor heterogeneity is a major clinical problem because tumor cell subtypes display variable sensitivity to therapeutics and may play different roles in progression. We previously characterized 2 cell populations in human breast tumors with distinct properties: CD44+CD24– cells that have stem cell-like characteristics, and CD44–CD24+ cells that resemble more differentiated breast cancer cells. Here we identified 15 genes required for cell growth or proliferation in CD44+CD24– human breast cancer cells in a large-scale loss-of-function screen and found that inhibition of several of these (IL6, PTGIS, HAS1, CXCL3, and PFKFB3) reduced Stat3 activation. We found that the IL-6/JAK2/Stat3 pathway was preferentially active in CD44+CD24– breast cancer cells compared with other tumor cell types, and inhibition of JAK2 decreased their number and blocked growth of xenografts. Our results highlight the differences between distinct breast cancer cell types and identify targets such as JAK2 and Stat3 that may lead to more specific and effective breast cancer therapies.

Authors

Lauren L.C. Marotta, Vanessa Almendro, Andriy Marusyk, Michail Shipitsin, Janina Schemme, Sarah R. Walker, Noga Bloushtain-Qimron, Jessica J. Kim, Sibgat A. Choudhury, Reo Maruyama, Zhenhua Wu, Mithat Gönen, Laura A. Mulvey, Marina O. Bessarabova, Sung Jin Huh, Serena J. Silver, So Young Kim, So Yeon Park, Hee Eun Lee, Karen S. Anderson, Andrea L. Richardson, Tatiana Nikolskaya, Yuri Nikolsky, X. Shirley Liu, David E. Root, William C. Hahn, David A. Frank, Kornelia Polyak

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Figure 6

Regulation of the JAK2/Stat3 pathway in basal-like breast cancer cells and its clinical significance in primary human breast tumors.

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Regulation of the JAK2/Stat3 pathway in basal-like breast cancer cells a...
(A) Immunoblots of pStat3 in basal-like breast cancer cell lines (and MCF7, in which pStat3 is undetectable by immunoblot) after 6-hour inhibitor treatments. Concentrations used were 2 μM JAK, 1 mM PTGIS, 1.5 μM CXCR2, 10 μM PFKFB3, 1 mM HAS1, and 50 μM NQO1 inhibitor. Stat3 was used as a loading control. (B) Quantitation of basal-like immunoblots in A. pStat3/Stat3 values represent ratios to control (no drug). (C) Luciferase assay results using Hs 578T and MCF7 cells treated with inhibitors for 2 days. Error bars show SD of triplicates. **P < 0.01; ***P < 0.001, t test. (D and F) Fold changes in tag counts for genes in our Hs 578T and MCF7 Stat3 signatures in SAGE-Seq libraries prepared from Hs 578T or MCF7 cells treated for 2 days with STAT3 siRNAs (versus nontargeting siRNAs) or inhibitors (versus no drug). Red and green indicate high and low fold changes, respectively. Each gene in the signatures had |fold change| > 2 with STAT3 siRNAs and in the same direction with at least 4 inhibitors (not NQO1). (E and G) Significant association of the presence of the Hs 578T Stat3 signature with shorter distant metastasis-free survival in 2 cohorts of breast cancer patients and lack of such an association for the MCF7 Stat3 signature. Kaplan-Meier curves (for n patients with and without each signature) and their corresponding log-rank test P values are shown.