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 4

Importance of the IL-6/JAK2/Stat3 pathway in tumor growth.

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Importance of the IL-6/JAK2/Stat3 pathway in tumor growth. (A) Represent...
(A) Representative immunofluorescence staining patterns for CD44, CD24, and pStat3 in ER–PR–HER2+ inflammatory breast carcinoma (IDC31). Scale bar: 10 microns. (B) Representative immunofluorescence staining patterns for CD44, CD24, and pStat3 in SUM159PT and IDC31 xenografts. Scale bars: 10 microns. (C) Box plots showing percentage of pStat3+ cells in SUM159PT and IDC31 mouse xenograft-derived (IDC31-X) xenografts by immunofluorescence and immunohistochemistry, respectively (counting 2–6 fields per sample). (D) Box plots showing xenograft tumor weights 34, 28, 28, 40, or 70 days after injecting SUM159PT, MDA-MB-231, MDA-MB-468, Hs 578T, or IDC31-X cells, respectively, into 2 fat pads of n mice. Mice were administered daily NVP-BSK805 (2 mg/mouse) or vehicle only (control) for 14, 16, 16, 24, or 24 days, respectively (after tumors reached palpable size), beginning 21, 13, 13, 17, or 47 days after injection, respectively. (E) H&E-stained Hs 578T and IDC31-X xenografts. (F) Box plots showing the percentage of area with cells in Hs 578T and IDC31-X xenografts calculated from whole tumor sections with H&E staining. (G) Kaplan-Meier curves of SUM159PT xenografts expressing STAT3 shRNAs (shSTAT3 #1 and #2) in n mice. (H) Immunoblots with cells used for xenografts in G. Tubulin was used as a loading control. (I) pStat3 immunohistochemistry staining for xenografts in G. Scale bars: 50 microns. Triangles in C, D, and F mark averages. *P < 0.05; **P < 0.01; ***P < 0.001, t test (C, D, and F). ***P < 0.001, log-rank test (comparing each STAT3 shRNA group to the shGFP control group) (G).