TY - JOUR
T1 - The small GTPase ARf6 activates PI3K in melanoma to induce a prometastatic state
AU - Yoo, Jae Hyuk
AU - Brady, Samuel W.
AU - Acosta-Alvarez, Lehi
AU - Rogers, Aaron
AU - Peng, Jingfu
AU - Sorensen, Lise K.
AU - Wolff, Roger K.
AU - Mleynek, Tara
AU - Shin, Donghan
AU - Rich, Coulson P.
AU - Kircher, David A.
AU - Bild, Andrea
AU - Odelberg, Shannon J.
AU - Li, Dean Y.
AU - Holmen, Sheri L.
AU - Grossmann, Allie H.
N1 - Funding Information:
This study was supported by the National Cancer Institute K08 CA188563-01A1, R01 CA121118, K99 CA230312, the Melanoma Research Alliance MRA 347651, a Harold J. Lloyd Charitable Trust Career Development Award, NCI R01CA202778, NIAMS R01AR064788, NHLBI R01HL130541, T32HL007576-31, U54CA209978. We thank several shared resources at the Huntsman Cancer Institute: High-Throughput Genomics, Biorepository Molecular Pathology, and Bioinformatics are supported by award P30CA042014 from the National Cancer Institute and the Preclinical Research Resource, which provided experimental metastasis modeling services. We also thank Health Science Cores at the University of Utah: Genomics Core Facility; DNA Sequencing Core Facility; Fluorescence Microscopy Core Facility, supported by NCRR Shared Equipment Grant # 1S10RR024761-01. We thank the MDACC RPPA Core facility, funded by NCI CA16672. We thank Drs. R. Andtbacka, J. Hyngstrom, and R.D. Kim for patient specimen procurement. We thank C. Stubben for bioinformatics support and Dr. K. Boucher for biostatistics input in the TCGA survival correlates. We thank Drs. D. Grossman and M. VanBrocklin for human cell lines, Dr. M. McMahon for scientific and technical input, Drs. J. Kaplan and A. Anderson for manuscript editing, Dr. Z.Z. Tong and Navigen, Inc., for ARF6 plasmid constructs and D. Lim for graphics preparation.
Publisher Copyright:
© 2019 American Association for Cancer Research.
PY - 2019/6/1
Y1 - 2019/6/1
N2 - Melanoma has an unusual capacity to spread in early-stage disease, prompting aggressive clinical intervention in very thin primary tumors. Despite these proactive efforts, patients with low-risk, low-stage disease can still develop metastasis, indicating the presence of permissive cues for distant spread. Here, we show that constitutive activation of the small GTPase ARF6 (ARF6Q67L) is sufficient to accelerate metastasis in mice with BRAFV600E/Cdkn2aNULL melanoma at a similar incidence and severity to Pten loss, a major driver of PI3K activation and melanoma metastasis. ARF6Q67L promoted spontaneous metastasis from significantly smaller primary tumors than PTENNULL, implying an enhanced ability of ARF6-GTP to drive distant spread. ARF6 activation increased lung colonization from circulating melanoma cells, suggesting that the prometastatic function of ARF6 extends to late steps in metastasis. Unexpectedly, ARF6 tumors showed upregulation of Pik3r1 expression, which encodes the p85 regulatory subunit of PI3K. Tumor cells expressing ARF6Q67L displayed increased PI3K protein levels and activity, enhanced PI3K distribution to cellular protrusions, and increased AKT activation in invadopodia. ARF6 is necessary and sufficient for activation of both PI3K and AKT, and PI3K and AKT are necessary for ARF6-mediated invasion. We provide evidence for aberrant ARF6 activation in human melanoma samples, which is associated with reduced survival. Our work reveals a previously unknown ARF6-PI3K-AKT proinvasive pathway, it demonstrates a critical role for ARF6 in multiple steps of the metastatic cascade, and it illuminates how melanoma cells can acquire an early metastatic phenotype in patients. Significance: These findings reveal a prometastatic role for ARF6 independent of tumor growth, which may help explain how melanoma spreads distantly from thin, early-stage primary tumors.
AB - Melanoma has an unusual capacity to spread in early-stage disease, prompting aggressive clinical intervention in very thin primary tumors. Despite these proactive efforts, patients with low-risk, low-stage disease can still develop metastasis, indicating the presence of permissive cues for distant spread. Here, we show that constitutive activation of the small GTPase ARF6 (ARF6Q67L) is sufficient to accelerate metastasis in mice with BRAFV600E/Cdkn2aNULL melanoma at a similar incidence and severity to Pten loss, a major driver of PI3K activation and melanoma metastasis. ARF6Q67L promoted spontaneous metastasis from significantly smaller primary tumors than PTENNULL, implying an enhanced ability of ARF6-GTP to drive distant spread. ARF6 activation increased lung colonization from circulating melanoma cells, suggesting that the prometastatic function of ARF6 extends to late steps in metastasis. Unexpectedly, ARF6 tumors showed upregulation of Pik3r1 expression, which encodes the p85 regulatory subunit of PI3K. Tumor cells expressing ARF6Q67L displayed increased PI3K protein levels and activity, enhanced PI3K distribution to cellular protrusions, and increased AKT activation in invadopodia. ARF6 is necessary and sufficient for activation of both PI3K and AKT, and PI3K and AKT are necessary for ARF6-mediated invasion. We provide evidence for aberrant ARF6 activation in human melanoma samples, which is associated with reduced survival. Our work reveals a previously unknown ARF6-PI3K-AKT proinvasive pathway, it demonstrates a critical role for ARF6 in multiple steps of the metastatic cascade, and it illuminates how melanoma cells can acquire an early metastatic phenotype in patients. Significance: These findings reveal a prometastatic role for ARF6 independent of tumor growth, which may help explain how melanoma spreads distantly from thin, early-stage primary tumors.
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U2 - 10.1158/0008-5472.CAN-18-3026
DO - 10.1158/0008-5472.CAN-18-3026
M3 - Article
C2 - 31048499
AN - SCOPUS:85066471499
VL - 79
SP - 2892
EP - 2908
JO - Cancer Research
JF - Cancer Research
SN - 0008-5472
IS - 11
ER -