Mutational hotspot in exon 20 of PIK3CA in breast cancer among Singapore Chinese

Xiaohui Liang, Choon Lau Quek, Manuel Salto-Tellez, Thomas Choudary Putti, Marie Loh, Saraswati Sukumar

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18 Scopus citations


The recent identification of somatic mutations in the catalytic region of PIK3 (PIK3CA) in breast cancer and demonstration of their oncogenic function has implicated PIK3CA in mammary carcinogenesis. To investigate possible ethnic differences in patterns of PIK3CA mutations in Singaporean Chinese breast cancer and to characterize these in a panel of cell lines, we sequenced exons 9 and 20 in 80 primary tumors, 19 breast cancer cell lines and 7 normal human mammary epithelial cells (HMECs). Searching for novel hotspots of mutation, we sequenced additional exons (1, 2, 6, 7, 14 and 18) in 20 primary tumors and 6 breast cancer cell lines. We detected 33 point mutations in 31 of 80 (39%) breast cancers, and 11 mutations in 10 of 19 (53%) breast cancer cell lines. No mutations were detected in normal breast tissue adjacent to the tumor, or in the 6 normal HMECs. The exon 20 A3140G (H1047R) substitution was identified most frequently (22/31, 71%) and showed a significant association with patient age (p = 0.043) and stage of the disease (p = 0.025), but not with ER/PR status or histological grade of the tumor. The incidence of point mutations in PIK3CA, the A3140G substitution in particular, in Singapore breast cancers are among the most frequent reported to date for any gene in breast cancer. The results suggest that mutation of PIK3CA might contribute to development of early stage breast cancer and could provide a potent target for early diagnosis and therapy.

Original languageEnglish (US)
Pages (from-to)544-548
Number of pages5
JournalCancer Biology and Therapy
Issue number5
StatePublished - May 2006


  • Breast cancer
  • Mutation
  • Oncogene
  • PIK3CA

ASJC Scopus subject areas

  • Molecular Medicine
  • Oncology
  • Pharmacology
  • Cancer Research


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