Complete loss of PTEN protein expression correlates with shorter time to brain metastasis and survival in stage IIIB/C melanoma patients with BRAFV600 mutations.

Abstract

PURPOSE:

Loss of function of PTEN is a frequent event in melanoma, particularly in tumors with BRAF(V600) mutations. The prevalence, pathologic features, and clinical outcomes associated with PTEN loss in patients with stage IIIB/C melanoma were interrogated to improve our understanding of the clinical significance of this molecular event.

EXPERIMENTAL DESIGN:

Archival tissue from lymphadenectomy specimens among patients (n = 136) with stage IIIB or IIIC melanoma was assessed by DNA sequencing for activating BRAF and NRAS mutations, and by immunohistochemistry for the expression of PTEN protein. Associations of these molecular aberrations with demographics, tumor characteristics, and clinical outcomes were determined.

RESULTS:

The prevalence of BRAF(V600) mutations (40% overall), NRAS mutations (10%), and PTEN loss (25%) did not vary by pathologic substage. BRAF/NRAS mutation status did not correlate with distant disease-free survival (DDFS) or overall survival (OS). Complete loss of PTEN expression correlated with shorter OS but not DDFS. When stratified by specific sites of distant metastasis, PTEN loss was associated with significantly shorter time to melanoma brain metastasis (MBM), but not to liver, lung, or bone metastasis. Analysis of PTEN in mutationally defined subsets showed that PTEN loss was significantly associated with OS and time to MBM in patients with BRAF(V600) mutations.

CONCLUSIONS:

Loss of PTEN protein expression correlates significantly with decreased OS and time to MBM in stage IIIB/C melanoma patients with BRAF(V600) mutations. The findings add to evidence supporting a significant role for PTEN loss and the PI3K-AKT pathway in melanoma.

• Authors: Amanda D Bucheit, Guo Chen, Alan Siroy, Michael Tetzlaff, Russell Broaddus, Denai Milton, Patricia Fox, Roland Bassett, Patrick Hwu, Jeffrey E Gershenwald, Alexander J Lazar, Michael A Davies
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 20 Issue 21 Pg. 5527-36 (Nov 01 2014) ISSN: 1557-3265 [Electronic] United States
• PMID: 25165098 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2014 American Association for Cancer Research.

Chemical References

• Phosphatidylinositol 3-Kinases
• BRAF protein, human
• Proto-Oncogene Proteins B-raf
• Proto-Oncogene Proteins c-akt
• PTEN Phosphohydrolase
• PTEN protein, human

Topics

• Adult
• Aged
• Aged, 80 and over
• Brain (pathology)
• Brain Neoplasms (genetics, pathology, secondary)
• Disease-Free Survival
• Female
• Humans
• Male
• Melanoma (genetics, pathology)
• Middle Aged
• Mutation (genetics)
• PTEN Phosphohydrolase (genetics)
• Phosphatidylinositol 3-Kinases (genetics)
• Proto-Oncogene Proteins B-raf (genetics)
• Proto-Oncogene Proteins c-akt (genetics)
• Skin Neoplasms (genetics, pathology)
• Young Adult