HIF1α and HIF2α independently activate SRC to promote melanoma metastases
Sara C. Hanna, Bhavani Krishnan, Sean T. Bailey, Stergios J. Moschos, Pei-Fen Kuan, Takeshi Shimamura, Lukas D. Osborne, Marni B. Siegel, Lyn M. Duncan, E. Tim O’Brien III, Richard Superfine, C. Ryan Miller, M. Celeste Simon, Kwok-Kin Wong, William Y. Kim
Sara C. Hanna, Bhavani Krishnan, Sean T. Bailey, Stergios J. Moschos, Pei-Fen Kuan, Takeshi Shimamura, Lukas D. Osborne, Marni B. Siegel, Lyn M. Duncan, E. Tim O’Brien III, Richard Superfine, C. Ryan Miller, M. Celeste Simon, Kwok-Kin Wong, William Y. Kim
View: Text | PDF
Research Article Oncology

HIF1α and HIF2α independently activate SRC to promote melanoma metastases

Abstract

Malignant melanoma is characterized by a propensity for early lymphatic and hematogenous spread. The hypoxia-inducible factor (HIF) family of transcription factors is upregulated in melanoma by key oncogenic drivers. HIFs promote the activation of genes involved in cancer initiation, progression, and metastases. Hypoxia has been shown to enhance the invasiveness and metastatic potential of tumor cells by regulating the genes involved in the breakdown of the ECM as well as genes that control motility and adhesion of tumor cells. Using a Pten-deficient, Braf-mutant genetically engineered mouse model of melanoma, we demonstrated that inactivation of HIF1α or HIF2α abrogates metastasis without affecting primary tumor formation. HIF1α and HIF2α drive melanoma invasion and invadopodia formation through PDGFRα and focal adhesion kinase–mediated (FAK-mediated) activation of SRC and by coordinating ECM degradation via MT1-MMP and MMP2 expression. These results establish the importance of HIFs in melanoma progression and demonstrate that HIF1α and HIF2α activate independent transcriptional programs that promote metastasis by coordinately regulating cell invasion and ECM remodeling.

Authors

Sara C. Hanna, Bhavani Krishnan, Sean T. Bailey, Stergios J. Moschos, Pei-Fen Kuan, Takeshi Shimamura, Lukas D. Osborne, Marni B. Siegel, Lyn M. Duncan, E. Tim O’Brien III, Richard Superfine, C. Ryan Miller, M. Celeste Simon, Kwok-Kin Wong, William Y. Kim

×

Figure 5

Expression of stabilized HIF1α and HIF2α are sufficient to enhance normoxic melanoma cell invasion.

Options: View larger image (or click on image) Download as PowerPoint
Expression of stabilized HIF1α and HIF2α are sufficient to enhance normo...
(A) A375 SM and WM2664 cells were infected with retrovirus to stably express EGFP or stabilized versions of HIF1α (HIF1dPA) or HIF2α (HIF2dPA). Whole-cell extracts were immunoblotted with the indicated antibodies. (B) Representative photomicrographs of A375 SM and WM2664 cells stably expressing EGFP, HIF1dPA, or HIF2dPA, which have invaded through Matrigel chambers. Original magnification, ×10. (C) Quantification of A375 SM and WM2664 cells stably expressing EGFP, HIF1dPA, or HIF2dPA, which have invaded through Matrigel chambers. (D) Representative immunofluorescence images of A375 SM cells stably expressing EGFP, HIF1dPA, or HIF2dPA and plated on Alexa Fluor 568–conjugated fibronectin and stained with the indicated antibodies. Original magnification, ×63. Invadopodia were defined as colocalization of cortactin, F-actin (phalloidin), and degradation of Alexa Fluor 568 fibronectin and are indicated with yellow arrowheads. (E) Quantification of the percentage of cells with active invadopodia in A375 SM and WM2664 cells stably expressing EGFP, HIF1dPA, or HIF2dPA. (F) Whole-cell extracts from A375 SM and WM2664 cells stably expressing EGFP, HIF1dPA, or HIF2dPA were immunoblotted with the indicated antibodies. (G) A375 SM cells stably expressing EGFP, HIF1dPA, or HIF2dPA were allowed to adhere to fibronectin-conjugated magnetic beads and subjected to repeated magnetic pulses; the resultant motion and recovery were quantified and used to calculate cell stiffness in Pascals (Pa). Error bars show SEM. ***P < 0.0005; **P < 0.005; *P < 0.05.