Mutation‐specific antibody detects mutant BRAFV600E protein expression in human colon carcinomas. Issue 15 (8th May 2013)

• Record Type: Journal Article
• Authors: Sinicrope, Frank A.; Smyrk, Thomas C.; Tougeron, David; Thibodeau, Stephen N.; Singh, Shalini; Muranyi, Andrea; Shanmugam, Kandavel; Grogan, Thomas M.; Alberts, Steven R.; Shi, Qian
• Is Part Of: Cancer. Volume 119:Issue 15(2013)
• Page Start: 2765
• Page End: 2770
• Publication Date: 2013-05-08
• Subjects: Cancer -- Periodicals; Cancer -- Cytopathology -- Periodicals; 616.99405
• DOI: 10.1002/cncr.28133
• Languages: English
• ISSNs: 0008-543X

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="cncr28133-sec-0001" sec-type="section"> <title>BACKGROUND</title> <p>A point mutation (V600E) in the <italic>BRAF</italic> oncogene is a prognostic biomarker and may predict for nonresponse to anti‐EGFR antibody therapy in patients with colorectal carcinoma. <italic>BRAF<sup>V600E</sup></italic> mutations are frequently detected in tumors with microsatellite instability and indicate a sporadic origin. We used a mutation‐specific antibody to examine mutant BRAF<sup>V600E</sup> protein expression and its concordance with <italic>BRAF<sup>V600E</sup></italic> mutation data.</p> </sec> <sec id="cncr28133-sec-0002" sec-type="section"> <title>METHODS</title> <p>Primary stage III colon carcinomas were analyzed for <italic>BRAF<sup>V600E</sup></italic> mutations in exon 15, and 50 <italic>BRAF<sup>V600E</sup></italic> mutation carriers and 25 wild‐type tumors were selected for analysis of BRAF proteins by immunohistochemistry (IHC). IHC was performed in archival tissue specimens using a pan‐BRAF antibody and a mutation‐specific antibody against BRAF<sup>V600E</sup> proteins. Staining was scored by 2 pathologists who were blinded to clinical and mutation data.</p> </sec> <sec id="cncr28133-sec-0003" sec-type="section"> <title>RESULTS</title> <p>Using a pan‐BRAF antibody, total BRAF protein expression was observed in the tumor cell cytoplasm in 74 of 75 colon carcinomas. A mutation‐specific antibody identified diffuse cytoplasmic staining of mutant BRAF<sup>V600E</sup> proteins in 49 of 74 cancers. Analysis using a polymerase chain reaction‐based assay revealed that all 49 of these cancers carried <italic>BRAF<sup>V600E</sup></italic> mutations. In contrast, BRAF<sup>V600E</sup> staining was absent in all 25 tumors that carried wild‐type copies of <italic>BRAF</italic>.</p> </sec> <sec id="cncr28133-sec-0004" sec-type="section"> <title>CONCLUSIONS</title> <p>A BRAF mutation‐specific (V600E) antibody detected tumors with <italic>BRAF<sup>V600E</sup></italic> mutations and exhibited complete concordance with a DNA‐based method. These results support the use of IHC as a simplified strategy to screen colorectal cancers for <italic>BRAF<sup>V600E</sup></italic> mutations in clinical practice. <bold><italic>Cancer</italic> 2013</bold>;119:2765–2770. © <italic>2013 American Cancer Society</italic>.</p> </sec> </abstract>