Prevalence of PIK3CA mutations and the SNP rs17849079 in Arab breast cancer patients

Bedri Karakas, Dilek Colak, Namik Kaya, Hazem Ghebeh, Abeer Al-Qasem, Fawziah Hendrayani, Mohamed Toulimat, Taher Al-Tweigeri, Ben Ho Park, Abdelilah Aboussekhra

Research output: Contribution to journalArticle

Abstract

Carcinomas initiate and progress due to genetic and epigenetic alterations in epithelial cells. However, recently, these alterations have also been reported in stromal fibroblasts. The gain-of-function mutations in the PI3K p110 catalytic subunit (PIK3CA) have been identified in many cancers with a current global incidence of 26% (18-40%) in breast carcinomas. We analyzed the mutational frequency of PIK3CA of three hotspots (exons 1, 9, and 20) in 81 primary invasive breast cancers (BC) and 25 cultured breast cancer-associated fibroblast (CAF) samples by Sanger sequencing in Arab breast cancer patients. Associations between the incidence of any PIK3CA mutation and several clinicopathologic characteristics were assessed using chi-square tests for categorical or t test for continuous variables. Furthermore, survival curves were estimated using the Kaplan-Meier method with the log rank test to evaluate the significance of their differences. We identified a total of 21 PIK3CA missense mutations with a frequency of 25.9%. The majority of the mutations, 17 out of 21 (81%), were in exon 20 (p.His1047Arg, p.His1047Lys, p.Thr1025Ala, p.Gly1049Arg, p.Asp1056Asn) while the remainder, 4 out of 21 (19%) were in exon 9 (p.Glu545Lys). PIK3CA mutations were significantly associated with lower grade and hormone receptor positivity. Although there was a favorable trend in overall survival for patients whose tumor harbored PIK3CA mutations, the difference was not statistically significant (P = 0.10). However, we did not detect any somatic mutations in CAFs. Furthermore, we have shown a high prevalence (8.2-fold) of a silent variant (SNP, rs17849079) in the Arab breast cancer population compared with disease-free individuals.

Original languageEnglish (US)
Pages (from-to)888-896
Number of pages9
JournalCancer Biology and Therapy
Volume14
Issue number10
DOIs
StatePublished - Oct 2013

Keywords

  • Breast cancer
  • CAF
  • Mutation
  • PI3K
  • PIK3CA
  • SNP

ASJC Scopus subject areas

  • Cancer Research
  • Oncology
  • Molecular Medicine
  • Pharmacology

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  • Cite this

    Karakas, B., Colak, D., Kaya, N., Ghebeh, H., Al-Qasem, A., Hendrayani, F., Toulimat, M., Al-Tweigeri, T., Park, B. H., & Aboussekhra, A. (2013). Prevalence of PIK3CA mutations and the SNP rs17849079 in Arab breast cancer patients. Cancer Biology and Therapy, 14(10), 888-896. https://doi.org/10.4161/cbt.25945