Journal
ONCOTARGET
Volume 8, Issue 15, Pages 24869-24881Publisher
IMPACT JOURNALS LLC
DOI: 10.18632/oncotarget.15276
Keywords
tumor spheres; cancer stem cells; breast cancer; TGFbeta; ERK
Categories
Funding
- Extramural Collaborative Research Grant of Cancer Research Institute, Kanazawa University
- MEXT [13327601]
- JSPS [15548647]
- AMED
- Grants-in-Aid for Scientific Research [15H04294] Funding Source: KAKEN
Ask authors/readers for more resources
Cancer stem cells are thought to be responsible for tumor growth, recurrence, and resistance to conventional cancer therapy. However, it is still unclear how they are maintained in tumor tissues. Here, we show that the growth differentiation factor 15 (GDF15), a member of the TGF beta family, may maintain cancer stem-like cells in breast cancer tissues by inducing its own expression in an autocrine/paracrine manner. We found that GDF15, but not TGF beta, increased tumor sphere formation in several breast cancer cell lines and patient-derived primary breast cancer cells. As expected, TGF beta strongly stimulated the phosphorylation of Smad2. GDF15 also stimulated the phosphorylation of Smad2, but the GDF15-induced tumor sphere forming efficiency was not significantly affected by treatment with SB431542, an inhibitor of the TGF beta signaling. Although TGF beta transiently activated ERK1/2, GDF15 induced prolonged activation of ERK1/2. Treatment with U0126, an inhibitor of the MEK-ERK1/2 signaling, greatly inhibited the GDF15-induced tumor sphere formation. Moreover, cytokine array experiments revealed that GDF15, but not TGF beta, is able to induce its own expression; furthermore, it appears to form an autocrine/paracrine circuit to continuously produce GDF15. In addition, we found heterogeneous expression levels of GDF15 among cancer cells and in human breast cancer tissues using immunohistochemistry. This may reflect a heterogeneous cancer cell population, including cancer stem-like cells and other cancer cells. Our findings suggest that GDF15 induces tumor sphere formation through GDF15-ERK1/2-GDF15 circuits, leading to maintenance of GDF15(high) cancer stem-like cells. Targeting GDF15 to break these circuits should contribute to the eradication of tumors.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available