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EPHA2 feedback activation limits the response to PDEδ inhibition in KRAS-dependent cancer cells
Yue-Hong Chen1,2, Hao Lv1,3, Ning Shen1
1School of Life Science, Shanghai University, Shanghai, 200444, China.
Abstract:
KRAS is one of the most important proto-oncogenes. Its mutations occur in almost all tumor types, and KRAS mutant cancer is still lack of effective therapy. Prenyl-binding protein phosphodiesterase-δ (PDEδ) is required for the plasma membrane association and subsequent activation of KRAS oncogenic signaling. Recently, targeting PDEδ has provided new promise for KRAS mutant tumors. However, the therapeutic potential of PDEδ inhibition remains obscure. In this study, we explored how PDEδ inhibition was responded in KRAS mutant cancer cells, and identified KRAS mutant subset responsive to PDEδ inhibition. We first performed siRNA screen of KRAS growth dependency of a small panel of human cancer lines, and identified a subset of KRAS mutant cancer cells that were highly dependent on KRAS signaling. Among these cells, only a fraction of KRAS-dependent cells responded to PDEδ depletion, though KRAS plasma membrane association was effectively impaired. We revealed that the persistent RAF/MEK/ERK signaling seemed responsible for the lack of response to PDEδ depletion. A kinase array further identified that the feedback activation of EPH receptor A2 (EPHA2) accounted for the compensatory activation of RAF/MEK/ERK signaling in these cells. Simultaneous inhibition of EPHA2 and PDEδ led to the growth inhibition of KRAS mutant cancer cells. Together, this study gains a better understanding of PDEδ-targeted therapeutic strategy and suggests the combined inhibition of EPHA2 and PDEδ as a potential therapy for KRAS mutant cancer.
Insights
Targeting prenyl-binding protein phosphodiesterase-δ (PDEδ) shows promise for KRAS mutant cancers. This study identified a subset of KRAS-dependent cells responsive to PDEδ inhibition, revealing a combined therapy approach.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Genetics
Background:
- KRAS proto-oncogenes are frequently mutated in various cancers, lacking effective targeted therapies.
- Prenyl-binding protein phosphodiesterase-δ (PDEδ) is crucial for KRAS oncogenic signaling activation.
- Targeting PDEδ presents a potential therapeutic strategy for KRAS-mutant cancers, but its efficacy is not fully understood.
Purpose of the Study:
- To investigate the response of KRAS mutant cancer cells to PDEδ inhibition.
- To identify specific KRAS mutant subsets that benefit from PDEδ inhibition.
- To explore combination therapies for KRAS mutant cancers.
Main Methods:
- siRNA screening to assess KRAS growth dependency in human cancer cell lines.
- Analysis of KRAS plasma membrane association and RAF/MEK/ERK signaling pathway activation.
- Kinase array to identify feedback signaling mechanisms.
- Evaluation of combined PDEδ and EPH receptor A2 (EPHA2) inhibition.
Main Results:
- A subset of KRAS-dependent cancer cells showed limited response to PDEδ depletion despite impaired KRAS membrane association.
- Persistent RAF/MEK/ERK signaling, driven by feedback activation of EPHA2, contributed to resistance.
- Combined inhibition of EPHA2 and PDEδ effectively suppressed the growth of KRAS mutant cancer cells.
Conclusions:
- PDEδ inhibition alone is insufficient for some KRAS mutant cancers due to compensatory signaling.
- Feedback activation of EPHA2 plays a key role in resistance to PDEδ inhibition.
- Combined inhibition of EPHA2 and PDEδ represents a promising therapeutic strategy for KRAS mutant cancers.
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