Oncogenic Alterations in PI3K Signaling Emulated Optogenetically Recapitulate Some Phenotypic Changes in Mammary...

Area of Science:

• Oncology
• Cell Biology
• Molecular Biology

Background:

• Cancer involves altered cellular signaling, but links between specific mutations, signal transduction, and cell phenotypes are unclear.
• Two common breast cancer mutations, PIK3CA H1047R and ErbB2 amplification, activate the PI3K-Akt pathway but yield different cellular outcomes.

Purpose of the Study:

• Investigate how distinct mutations in the PI3K-Akt pathway lead to different cellular phenotypes in breast cancer.
• Determine if the temporal dynamics of PI3K pathway activation, rather than just magnitude, influence phenotypic consequences.

Main Methods:

• Utilized an optogenetic system (iLID) for precise, tunable control of PI3K pathway activity in mammary epithelial cells.
• Expressed PIK3CA H1047R mutation or ErbB2 amplification in MCF10A cells to compare signaling dynamics and phenotypes.
• Mimicked mutation-specific PI3K signaling dynamics using optogenetics to assess their sufficiency in driving phenotypes.

Main Results:

• PIK3CA H1047R expression induced epithelial-mesenchymal transition (EMT) features, while ErbB2 amplification caused hyperproliferation.
• PIK3CA H1047R cells showed constitutive PI3K activation, whereas ErbB2 amplified cells displayed prolonged, stimulus-dependent activation.
• Optogenetic mimicry of PI3K signaling patterns reproduced EMT features associated with PIK3CA H1047R but not the proliferative phenotype of ErbB2 amplification.

Conclusions:

• Temporal patterns of PI3K pathway activity, not solely its magnitude, can drive distinct phenotypic changes in oncogenic progression.
• Explains how different mutations within a shared signaling pathway can result in divergent cellular phenotypes.
• Provides a novel optogenetic workflow for studying the functional impact of signaling dynamics in cancer.