NID2

NID2 is a basement membrane glycoprotein that functions as a tumor suppressor silenced by promoter DNA hypermethylation in multiple epithelial cancers; re-expression in nasopharyngeal, esophageal, and lung cancer cells suppresses clonogenic survival, migration, invasion, and in vivo tumor growth and metastasis by inhibiting EGFR/Akt and integrin/FAK/PLCγ signaling pathways (PMID:27793011, PMID:30826972). In vascular smooth muscle cells, NID2 promotes osteogenic transdifferentiation and diabetic vascular calcification by activating an IGF2-ERK1/2 signaling axis, a process normally restrained by epoxyeicosatrienoic acids (EETs) that suppress NID2 expression (PMID:40937642).

1. 2016 Medium

   Establishing NID2 as a functional tumor/metastasis suppressor resolved the question of whether its epigenetic silencing in carcinomas was causally linked to malignant phenotypes, revealing that NID2 re-expression inhibits EGFR/Akt and integrin/FAK/PLCγ signaling to suppress clonogenicity, migration, and liver metastasis.

   Evidence Stable NID2 re-expression in NPC and ESCC cell lines with clonogenic, migration, in vivo metastasis assays, and Western blot of pathway components

   PMID:27793011

   Open questions at the time

   • Direct physical interaction between NID2 and EGFR or integrins has not been demonstrated
   • Whether NID2 suppressor function is universal across cancer types or tissue-specific is unclear
   • No structural or biochemical basis for how extracellular NID2 modulates intracellular EGFR/Akt signaling
2. 2019 Medium

   Extending the tumor-suppressive role to lung cancer and demonstrating that NID2 overexpression induces apoptosis and inhibits xenograft growth reinforced NID2 as a broadly acting epithelial tumor suppressor silenced by DNA methylation.

   Evidence NID2 overexpression and demethylation in lung cancer cell lines with CCK-8, colony formation, transwell, apoptosis assays, and nude mouse xenograft models

   PMID:30826972

   Open questions at the time

   • Downstream signaling pathway specifics in lung cancer were not mapped as thoroughly as in NPC/ESCC
   • No loss-of-function genetics in normal tissue to establish physiological requirement
   • Apoptotic mechanism (intrinsic vs. extrinsic) induced by NID2 remains undefined
3. 2025 Medium

   Demonstrating that NID2 promotes vascular calcification via IGF2-ERK1/2 activation revealed a non-oncological, tissue-specific function in osteogenic transdifferentiation of smooth muscle cells, regulated upstream by EET-dependent suppression of NID2 expression.

   Evidence Ephx2-/- mice, AAV9-mediated NID2 overexpression in vivo, siRNA knockdown and sEH inhibitors in MOVAS cells, Western blot for IGF2/p-ERK1/2, calcification staining

   PMID:40937642

   Open questions at the time

   • How NID2, an extracellular matrix protein, activates intracellular IGF2-ERK1/2 signaling is mechanistically unresolved
   • Whether NID2-driven calcification involves the same integrin/EGFR pathways implicated in cancer is unknown
   • Single lab; independent replication pending

• The receptor(s) and direct molecular partners through which extracellular NID2 transduces signals into intracellular EGFR/Akt, integrin/FAK, and IGF2-ERK1/2 pathways remain unidentified, and no loss-of-function genetic model in normal epithelial tissue has established its physiological basement membrane role.
• No direct NID2-receptor binding partner has been biochemically identified
• No Nid2 knockout mouse phenotype characterization in the literature captured here
• Structural basis for NID2 integration into basement membrane and signaling is lacking