Activating mutations in PIK3CA lead to widespread modulation of the tyrosine phosphoproteome

Muhammad Saddiq Zahari, Xinyan Wu, Brian G. Blair, Sneha M. Pinto, Raja S. Nirujogi, Christine A. Jelinek, Radhika Malhotra, Min Sik Kim, Ben Ho Park, Akhilesh Pandey

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The human oncogene PIK3CA is frequently mutated in human cancers. Two hotspot mutations in PIK3CA, E545K and H1047R, have been shown to regulate widespread signaling events downstream of AKT, leading to increased cell proliferation, growth, survival, and motility. We used quantitative mass spectrometry to profile the global phosphotyrosine proteome of isogenic knock-in cell lines containing these activating mutations, where we identified 824 unique phosphopeptides. Although it is well understood that these mutations result in hyperactivation of the serine/threonine kinase AKT, we found a surprisingly widespread modulation of tyrosine phosphorylation levels of proteins in the mutant cells. In the tyrosine kinome alone, 29 tyrosine kinases were altered in their phosphorylation status. Many of the regulated phosphosites that we identified were located in the kinase domain or the canonical activation sites, indicating that these kinases and their downstream signaling pathways were activated. Our study demonstrates that there is frequent and unexpected cross-talk that occurs between tyrosine signaling pathways and serine/threonine signaling pathways activated by the canonical PI3K-AKT axis.

Original languageEnglish (US)
Pages (from-to)3882-3891
Number of pages10
JournalJournal of proteome research
Issue number9
StatePublished - Sep 4 2015

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry


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