Proceedings of the National Academy of Sciences of the United States of America, Dec 11, 2017
Triple-negative breast cancer (TNBC), the deadliest form of this disease, lacks a targeted therap... more Triple-negative breast cancer (TNBC), the deadliest form of this disease, lacks a targeted therapy. TNBC tumors that fail to respond to chemotherapy are characterized by a repressed IFN/signal transducer and activator of transcription (IFN/STAT) gene signature and are often enriched for cancer stem cells (CSCs). We have found that human mammary epithelial cells that undergo an epithelial-to-mesenchymal transition (EMT) following transformation acquire CSC properties. These mesenchymal/CSCs have a significantly repressed IFN/STAT gene expression signature and an enhanced ability to migrate and form tumor spheres. Treatment with IFN-beta (IFN-β) led to a less aggressive epithelial/non-CSC-like state, with repressed expression of mesenchymal proteins (VIMENTIN, SLUG), reduced migration and tumor sphere formation, and reexpression of CD24 (a surface marker for non-CSCs), concomitant with an epithelium-like morphology. The CSC-like properties were correlated with high levels of unphospho...
Epithelial to mesenchymal transition (EMT) is an important process in both metastasis and cancer ... more Epithelial to mesenchymal transition (EMT) is an important process in both metastasis and cancer stem cell (CSC) enrichment. Recent studies suggest that instead of simply transitioning from one cell state to another, cancer cells exist along a continuum of epithelial and mesenchymal cell states. Identifying novel regulators of tumor cell plasticity will be critical to fully understand this continuum and to target metastasis and CSC phenotypes in the future. FAM83B is a novel oncogene identified by the Jackson Laboratory in a forward genetic screen for drivers of Human Mammary Epithelial Cell (HMEC) transformation. Previous work showed that FAM83B expression is elevated in triple negative breast cancers and that FAM83B also activates key cell signaling pathways (EGFR, MAPK, and PI3K) in breast cancers. Here, we implicate FAM83B as a novel regulator of epithelial-mesenchymal plasticity using a HMEC transformation model. Transformation of primary HMEC by expressing shp16, shp53, c-Myc,...
Increasing evidence suggests that tumor cell plasticity promotes metastasis and tumor recurrence,... more Increasing evidence suggests that tumor cell plasticity promotes metastasis and tumor recurrence, resulting in cancer patient mortality. While it is clear that the tumor microenvironment (TME) contributes to tumor cell plasticity, the specific TME factors that actively generate tumor cell plasticity are largely unknown. Here, we identify TME cytokines that promote epithelial-mesenchymal plasticity, and acquisition of cancer stem-cell (CSC) properties. A screen of 27 TME cytokines identified multiple Interleukin-6 family members as inducers of mesenchymal/CSC properties, with Oncostatin M (OSM) being the most potent. Importantly, OSM induced plasticity was mediated by STAT3, but also dependent on TGF-β signaling and downstream SMAD3. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented the OSM-induced mesenchymal/CSC properties. OSM-activa...
Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent ... more Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent progression towards metastasis. Elevated levels of the Interleukin-6 (IL-6) family cytokine Oncostatin M (OSM) in the breast TME correlate with aggressive, metastatic cancers, increased tumor recurrence, and poor patient prognosis. Paradoxically, OSM engages a tumor-suppressive, Signal Transducer and Activator of Transcription 3 (STAT3)-dependent senescence response in normal and non-transformed human mammary epithelial cells (HMEC). Here, we identify a novel link between OSM-activated STAT3 signaling and the Transforming Growth Factor-β (TGF-β) signaling pathway that engages senescence in HMEC. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented OSM-induced senescence. OSM promoted a protein complex involving activated-STAT3 and SMAD3, induc...
The connection between epithelial-mesenchymal (E-M) plasticity and cancer stem cell (CSC) propert... more The connection between epithelial-mesenchymal (E-M) plasticity and cancer stem cell (CSC) properties has been paradigm-shifting, linking tumor cell invasion and metastasis with therapeutic recurrence. However, despite their importance, the molecular pathways involved in generating invasive, metastatic, and therapy-resistant CSCs remain poorly understood. The enrichment of cells with a mesenchymal/CSC phenotype following therapy has been interpreted in two different ways. The original interpretation posited that therapy kills non-CSCs while sparing pre-existing CSCs. However, evidence is emerging that suggests non-CSCs can be induced into a transient, drug-tolerant, CSC-like state by chemotherapy. The ability to transition between distinct cell states may be as critical for the survival of tumor cells following therapy as it is for metastatic progression. Therefore, inhibition of the pathways that promote E-M and CSC plasticity may suppress tumor recurrence following chemotherapy. He...
Proceedings of the National Academy of Sciences of the United States of America, Dec 11, 2017
Triple-negative breast cancer (TNBC), the deadliest form of this disease, lacks a targeted therap... more Triple-negative breast cancer (TNBC), the deadliest form of this disease, lacks a targeted therapy. TNBC tumors that fail to respond to chemotherapy are characterized by a repressed IFN/signal transducer and activator of transcription (IFN/STAT) gene signature and are often enriched for cancer stem cells (CSCs). We have found that human mammary epithelial cells that undergo an epithelial-to-mesenchymal transition (EMT) following transformation acquire CSC properties. These mesenchymal/CSCs have a significantly repressed IFN/STAT gene expression signature and an enhanced ability to migrate and form tumor spheres. Treatment with IFN-beta (IFN-β) led to a less aggressive epithelial/non-CSC-like state, with repressed expression of mesenchymal proteins (VIMENTIN, SLUG), reduced migration and tumor sphere formation, and reexpression of CD24 (a surface marker for non-CSCs), concomitant with an epithelium-like morphology. The CSC-like properties were correlated with high levels of unphospho...
Epithelial to mesenchymal transition (EMT) is an important process in both metastasis and cancer ... more Epithelial to mesenchymal transition (EMT) is an important process in both metastasis and cancer stem cell (CSC) enrichment. Recent studies suggest that instead of simply transitioning from one cell state to another, cancer cells exist along a continuum of epithelial and mesenchymal cell states. Identifying novel regulators of tumor cell plasticity will be critical to fully understand this continuum and to target metastasis and CSC phenotypes in the future. FAM83B is a novel oncogene identified by the Jackson Laboratory in a forward genetic screen for drivers of Human Mammary Epithelial Cell (HMEC) transformation. Previous work showed that FAM83B expression is elevated in triple negative breast cancers and that FAM83B also activates key cell signaling pathways (EGFR, MAPK, and PI3K) in breast cancers. Here, we implicate FAM83B as a novel regulator of epithelial-mesenchymal plasticity using a HMEC transformation model. Transformation of primary HMEC by expressing shp16, shp53, c-Myc,...
Increasing evidence suggests that tumor cell plasticity promotes metastasis and tumor recurrence,... more Increasing evidence suggests that tumor cell plasticity promotes metastasis and tumor recurrence, resulting in cancer patient mortality. While it is clear that the tumor microenvironment (TME) contributes to tumor cell plasticity, the specific TME factors that actively generate tumor cell plasticity are largely unknown. Here, we identify TME cytokines that promote epithelial-mesenchymal plasticity, and acquisition of cancer stem-cell (CSC) properties. A screen of 27 TME cytokines identified multiple Interleukin-6 family members as inducers of mesenchymal/CSC properties, with Oncostatin M (OSM) being the most potent. Importantly, OSM induced plasticity was mediated by STAT3, but also dependent on TGF-β signaling and downstream SMAD3. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented the OSM-induced mesenchymal/CSC properties. OSM-activa...
Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent ... more Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent progression towards metastasis. Elevated levels of the Interleukin-6 (IL-6) family cytokine Oncostatin M (OSM) in the breast TME correlate with aggressive, metastatic cancers, increased tumor recurrence, and poor patient prognosis. Paradoxically, OSM engages a tumor-suppressive, Signal Transducer and Activator of Transcription 3 (STAT3)-dependent senescence response in normal and non-transformed human mammary epithelial cells (HMEC). Here, we identify a novel link between OSM-activated STAT3 signaling and the Transforming Growth Factor-β (TGF-β) signaling pathway that engages senescence in HMEC. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented OSM-induced senescence. OSM promoted a protein complex involving activated-STAT3 and SMAD3, induc...
The connection between epithelial-mesenchymal (E-M) plasticity and cancer stem cell (CSC) propert... more The connection between epithelial-mesenchymal (E-M) plasticity and cancer stem cell (CSC) properties has been paradigm-shifting, linking tumor cell invasion and metastasis with therapeutic recurrence. However, despite their importance, the molecular pathways involved in generating invasive, metastatic, and therapy-resistant CSCs remain poorly understood. The enrichment of cells with a mesenchymal/CSC phenotype following therapy has been interpreted in two different ways. The original interpretation posited that therapy kills non-CSCs while sparing pre-existing CSCs. However, evidence is emerging that suggests non-CSCs can be induced into a transient, drug-tolerant, CSC-like state by chemotherapy. The ability to transition between distinct cell states may be as critical for the survival of tumor cells following therapy as it is for metastatic progression. Therefore, inhibition of the pathways that promote E-M and CSC plasticity may suppress tumor recurrence following chemotherapy. He...
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