other-cancer

Cancer-causing mutations in MEN1 gastrinomas may work by blocking a nuclear protein rather than destroying it

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary syndrome associated with aggressive neuroendocrine tumors, including gastrinomas — tumors arising from the duodenum that cause excess gastrin production. While MEN1 is a well-known tumor suppressor gene, many duodenal gastrinomas retain a…

Dan Manning

Dan Manning

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Cancer-causing mutations in MEN1 gastrinomas may work by blocking a nuclear protein rather than destroying it

Cancer-causing mutations in MEN1 gastrinomas may work by blocking a nuclear protein rather than destroying it

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary syndrome associated with aggressive neuroendocrine tumors, including gastrinomas — tumors arising from the duodenum that cause excess gastrin production. While MEN1 is a well-known tumor suppressor gene, many duodenal gastrinomas retain a functional copy of MEN1, suggesting the protein itself is being inactivated by other means.

This study investigated posttranslational regulation of Menin (the protein encoded by MEN1). Researchers found that a specific phosphorylation site (Ser487) in Menin's C-terminal domain is targeted by extracellular growth factors, blocking one of Menin's nuclear localization signals. This means extracellular signaling can functionally inactivate Menin without mutating the gene — explaining how MEN1 wild-type gastrinomas lose Menin tumor-suppressor function.

This finding reframes MEN1 gastrinoma biology: rather than gene deletion, posttranslational inactivation via phosphorylation may be the dominant mechanism, opening new therapeutic angles targeting the signaling pathways that drive this modification.

Key Findings

  • Menin Ser487 phosphorylation blocks nuclear localization signal NLS1 in response to extracellular signaling
  • Wild-type MEN1 gastrinomas may lose Menin function through posttranslational inactivation rather than genetic mutation
  • Extracellular growth factors regulate Menin nuclear redistribution through site-specific phosphorylation
  • Duodenal Brunner's glands are rich in extracellular growth factors that could drive this phosphorylation
  • Posttranslational Menin inactivation could explain tumor development without MEN1 gene mutation

Implications

If extracellular signaling can functionally inactivate Menin through phosphorylation, then blocking the signaling pathways responsible could restore Menin tumor-suppressor function in gastrinomas — even in tumors without MEN1 gene mutations. This could expand treatment options and explain why some MEN1 pathway drugs show broader efficacy than expected.

Caveats

Preprint, not peer reviewed. Mechanistic findings need validation in patient tumor samples. The therapeutic implications of restoring Menin nuclear localization are still speculative. Summary based on abstract only.

Source: bioRxiv — 2026-04-10

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