Distinct (Phospho)proteomic Landscapes of PIK3CA Mutants Reveal Insulin-Mediated Reactivation of PI3K Pathway and Adaptive MAPK Signaling

ABSTRACT: Oncogenic mutations in p110α subunit of phosphatidylinositol-3-kinase (PI3K), primarily H1047R in the kinase domain and E545K in the helical domain, induce constitutive PI3K/AKT pathway activation, driving tumor progression. Isoform-specific inhibitors such as alpelisib have been developed, but their clinical efficacy is often compromised by on-target metabolic side effects, particularly hyperglycemia and insulin feedback that reactivates PI3K signaling. To better understand the signaling response in PI3K mutants and insulin-mediated tumor resistance, using MCF10A epithelial cells harboring PI3K hotspot mutations (H1047R or E545K), we conducted comprehensive proteomic and phosphoproteomic analyses under varying conditions—alpelisib treatment, insulin stimulation, and their combination. We observed mutation specific responses in growth kinetics, proteome states, and dynamic signaling response. We observed that insulin effectively rescues mutant cells from alpelisib-induced inhibition through the reactivation of PI3K pathway and the adaptive reprogramming, especially activation of the MAPK pathways. These findings indicate that combination therapies targeting both the PIK3CA mutation and MAPK pathways may be necessary to overcome challenges faced by PI3Kα inhibitors and achieve more durable clinical responses.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Cell Culture

DISEASE(S): Breast Cancer

SUBMITTER: Fujia Wang  

LAB HEAD: Kelly E. Stecker

PROVIDER: PXD067648 | Pride | 2026-09-07

REPOSITORIES: Pride