Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/92142
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Type: Journal article
Title: PIK3CA activating mutation in colorectal carcinoma: associations with molecular features and survival
Author: Rosty, C.
Young, J.
Walsh, M.
Clendenning, M.
Sanderson, K.
Walters, R.
Parry, S.
Jenkins, M.
Win, A.
Southey, M.
Hopper, J.
Giles, G.
Williamson, E.
English, D.
Buchanan, D.
Citation: PLoS One, 2013; 8(6):e65479-1-e65479-9
Publisher: Public Library of Science
Issue Date: 2013
ISSN: 1932-6203
1932-6203
Editor: Ashktorab, H.
Statement of
Responsibility: 
Christophe Rosty, Joanne P. Young, Michael D. Walsh, Mark Clendenning, Kristy Sanderson, Rhiannon J. Walters, Susan Parry, Mark A. Jenkins, Aung Ko Win, Melissa C. Southey, John L. Hopper, Graham G. Giles, Elizabeth J. Williamson, Dallas R. English, Daniel D. Buchanan
Abstract: Mutations in PIK3CA are present in 10 to 15% of colorectal carcinomas. We aimed to examine how PIK3CA mutations relate to other molecular alterations in colorectal carcinoma, to pathologic phenotype and survival. PIK3CA mutation testing was carried out using direct sequencing on 757 incident tumors from the Melbourne Collaborative Cohort Study. The status of O-6-methylguanine-DNA methyltransferase (MGMT) was assessed using both immunohistochemistry and methyLight techniques. Microsatellite instability, CpG island phenotype (CIMP), KRAS and BRAF V600E mutation status, and pathology review features were derived from previous reports. PIK3CA mutation was observed in 105 of 757 (14%) of carcinomas, characterized by location in the proximal colon (54% vs. 34%; P<0.001) and an increased frequency of KRAS mutation (48% vs. 25%; P<0.001). High-levels of CIMP were more frequently found in PIK3CA-mutated tumors compared with PIK3CA wild-type tumors (22% vs. 11%; P = 0.004). There was no difference in the prevalence of BRAF V600E mutation between these two tumor groups. PIK3CA-mutated tumors were associated with loss of MGMT expression (35% vs. 20%; P = 0.001) and the presence of tumor mucinous differentiation (54% vs. 32%; P<0.001). In patients with wild-type BRAF tumors, PIK3CA mutation was associated with poor survival (HR 1.51 95% CI 1.04-2.19, P = 0.03). In summary, PIK3CA-mutated colorectal carcinomas are more likely to develop in the proximal colon, to demonstrate high levels of CIMP, KRAS mutation and loss of MGMT expression. PIK3CA mutation also contributes to significantly decreased survival for patients with wild-type BRAF tumors.
Keywords: Colorectal Neoplasms
Rights: © 2013 Rosty et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DOI: 10.1371/journal.pone.0065479
Grant ID: http://purl.org/au-research/grants/nhmrc/509348
http://purl.org/au-research/grants/nhmrc/209057
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