Breast cancer cells respond differentially to modulation of TGFβ2 signaling after exposure to chemotherapy or hypoxia.
Intratumoral heterogeneity helps drive the selection for diverse therapy-resistant cell populations. In this study, we demonstrate the coexistence of two therapy-resistant populations with distinct properties that are reproducibly enriched under conditions that characterize tumor pathophysiology. Breast cancer cells that survived chemotherapy or hypoxia were enriched for cells expressing the major hyaluronic acid receptor CD44. However, only CD44(hi) cells that survived chemotherapy exhibited cancer stem cell (CSC) phenotypes based on growth potential and gene expression signatures that represent oncogenic signaling and metastatic prowess. Strikingly, we identified TGFβ2 as a key growth promoter of CD44(hi) cells that survived chemotherapy but also as a growth inhibitor of cells that survived hypoxia. Expression of the TGFβ receptor TGFβR1 and its effector molecule SMAD4 was required for enrichment of CD44(hi) cells exposed to the chemotherapeutic drug epirubicin, which suggests a feed-forward loop to enrich for and enhance the function of surviving CSCs. Our results reveal context-dependent effects of TGFβ2 signaling in the same tumor at the same time. The emergence of distinct resistant tumor cell populations as a consequence of prior therapeutic intervention or microenvironmental cues has significant implications for the responsiveness of recurring tumors to therapy.
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Siobhan K
SK
O'Brien
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Liang
L
Chen
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Wenyan
W
Zhong
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Douglas
D
Armellino
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Jiyang
J
Yu
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Christine
C
Loreth
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York.
Maximillian
M
Follettie
Oncology Research Unit, Pfizer Worldwide Research and Development, Pearl River, New York. marc.damelin@pfizer.com.
Marc
M
Damelin
D000693:Anaerobiosis; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D015251:Epirubicin / Q000494:pharmacology; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics*; D061986:MCF-7 Cells; D014411:Neoplastic Stem Cells / Q000473:pathology; D034622:RNA Interference; D034741:RNA, Small Interfering; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics*; D051901:Smad4 Protein / Q000096:biosynthesis* / Q000235:genetics; D053781:Transforming Growth Factor beta2 / Q000378:metabolism*
D000903:Antibiotics, Antineoplastic; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D034741:RNA, Small Interfering; D018125:Receptors, Transforming Growth Factor beta; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D053781:Transforming Growth Factor beta2; D015251:Epirubicin