Sphingomyelin Metabolism Is a Regulator of K-Ras Function

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• K-Ras protein localization to the plasma membrane (PM) is essential for its biological activity.
• Aberrant K-Ras signaling drives various cancers, necessitating targeted therapies.

Purpose of the Study:

• To investigate the role of sphingomyelin (SM) metabolism in K-Ras localization and function.
• To evaluate acid sphingomyelinase (ASM) inhibitors as potential therapeutics for K-Ras-driven cancers.

Main Methods:

• Utilized ASM inhibitors and other pharmacological agents targeting SM biosynthesis in mammalian cell lines and *Caenorhabditis elegans* models.
• Assessed K-RasG12V and phosphatidylserine (PtdSer) localization at the PM using RNA interference and pharmacological treatments.
• Evaluated tumor growth in mice and signaling pathways in *C. elegans*.

Main Results:

• ASM inhibitors, including tricyclic antidepressants, mislocalized PtdSer and K-RasG12V from the PM, inhibiting K-Ras signaling and cancer cell proliferation.
• Inhibition of K-Ras-driven tumor growth was observed in mice treated with the ASM inhibitor fendiline.
• Targeting enzymes in the SM biosynthetic pathway suppressed K-Ras ortholog LET-60 signaling in *C. elegans* and caused K-RasG12V mislocalization in mammalian cells.

Conclusions:

• Normal sphingomyelin metabolism is critical for K-Ras function and localization.
• ASM inhibitors and other modulators of SM metabolism show therapeutic potential for K-Ras-driven cancers.