Supplementary Figure S1. Epithelial-mesenchymal transition and PHD3 silencing | Supplementary Figure S2. PHD3 silencing promotes EMT through upregulation of TGFα. | Supplementary Figure S3. EGFR signaling and TGFα mediate the effects of PHD3 silencing on EMT. | Supplementary Figure S4. EMT induced by PHD3 depletion is HIF dependent. | Supplementary Figure S5. PHD3 silencing confers resistance to erlotinib in EGFR mutant lung cancer cells. | Supplementary Figure S6. TGFα activates EGFR signaling in the presence of erlotinib. | Supplementary Figure S7. Resistance to erlotinib is associated with decreased PHD3 expression. | Supplementary Materials and Methods
Funding
DFG
Deutsche Krebshilfe
Behring-Röntgen Foundation
Johannes Gutenberg University Mainz
Clusters of Excellence Cardio-Pulmonary System
University Frankfurt
EMBO Long-Term Fellowship
ARTICLE ABSTRACT
Lung cancer is the leading cause of cancer-related death worldwide, in large part due to its high propensity to metastasize and to develop therapy resistance. Adaptive responses to hypoxia and epithelial–mesenchymal transition (EMT) are linked to tumor metastasis and drug resistance, but little is known about how oxygen sensing and EMT intersect to control these hallmarks of cancer. Here, we show that the oxygen sensor PHD3 links hypoxic signaling and EMT regulation in the lung tumor microenvironment. PHD3 was repressed by signals that induce EMT and acted as a negative regulator of EMT, metastasis, and therapeutic resistance. PHD3 depletion in tumors, which can be caused by the EMT inducer TGFβ or by promoter methylation, enhanced EMT and spontaneous metastasis via HIF-dependent upregulation of the EGFR ligand TGFα. In turn, TGFα stimulated EGFR, which potentiated SMAD signaling, reinforcing EMT and metastasis. In clinical specimens of lung cancer, reduced PHD3 expression was linked to poor prognosis and to therapeutic resistance against EGFR inhibitors such as erlotinib. Reexpression of PHD3 in lung cancer cells suppressed EMT and metastasis and restored sensitivity to erlotinib. Taken together, our results establish a key function for PHD3 in metastasis and drug resistance and suggest opportunities to improve patient treatment by interfering with the feedforward signaling mechanisms activated by PHD3 silencing.Significance: This study links the oxygen sensor PHD3 to metastasis and drug resistance in cancer, with implications for therapeutic improvement by targeting this system. Cancer Res; 78(7); 1805–19. ©2018 AACR.
