Integrated molecular and clinical analysis of AKT activation in metastatic melanoma

Michael A. Davies, Katherine Stemke-Hale, E. Lin, Carmen Tellez, Wanleng Deng, Yennu N. Gopal, Scott E. Woodman, Tiffany C. Calderone, Zhenlin Ju, Alexander J. Lazar, Victor G. Prieto, Kenneth Aldape, Gordon B. Mills, Jeffrey E. Gershenwald

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    Abstract

    Purpose: Activation of the phosphoinositide 3-kinase (PI3K)-AKT pathway has been implicated in melanoma based primarily on the prevalence of mutations in PTEN and NRAS. To improve our understanding of the regulation and clinical significance of the PI3K-AKT pathway in melanoma, we quantitatively measured the levels of phosphorylated AKT, its substrate GSK3α/β, and its negative regulator PTEN in clinical metastases. Results were compared with mutational status, clinical outcomes, and sites of metastasis. Experimental Design: DNA and protein were isolated from dissected frozen melanoma metastases (n = 96). Activating mutations of BRAF, NRAS, AKT, PIK3CA, and KIT were detected by mass spectroscopy genotyping. Phosphorylated AKT (Ser473 and Thr308), P-GSK3α/β, and PTEN protein expression were measured by reverse-phase protein array. A panel of human melanoma cells lines (n = 58) was analyzed for comparison. Results: BRAF-mutant tumors had higher levels of P-AKT-Ser473 (P = 0.01), P-AKTThr308 (P = 0.002), and P-GSK3α/β (P = 0.08) than NRAS-mutant tumors. Analysis of individual tumors showed that almost all tumors with elevated P-AKT had low PTEN levels; NRAS-mutant tumors had normal PTEN and lower P-AKT. Similar results were observed in melanoma cell lines. Stage III melanoma patients did not differ in overall survival based on activation status of the PI3K-AKT pathway. Brain metastases had significantly higher P-AKT and lower PTEN than lung or liver metastases. Conclusions: Quantitative interrogation of the PI3K-AKT pathway in melanoma reveals unexpected significant differences in AKT activation by NRAS mutation and PTEN loss, and hyperactivation of AKT in brain metastases. These findings have implications for the rational development of targeted therapy for this disease.

    Original languageEnglish (US)
    Pages (from-to)7538-7546
    Number of pages9
    JournalClinical Cancer Research
    Volume15
    Issue number24
    DOIs
    StatePublished - Dec 15 2009

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    ASJC Scopus subject areas

    • Oncology
    • Cancer Research

    Cite this

    Davies, M. A., Stemke-Hale, K., Lin, E., Tellez, C., Deng, W., Gopal, Y. N., Woodman, S. E., Calderone, T. C., Ju, Z., Lazar, A. J., Prieto, V. G., Aldape, K., Mills, G. B., & Gershenwald, J. E. (2009). Integrated molecular and clinical analysis of AKT activation in metastatic melanoma. Clinical Cancer Research, 15(24), 7538-7546. https://doi.org/10.1158/1078-0432.CCR-09-1985