NOMO3

NOMO3 is implicated in the survival of lung cancer cells, where its silencing increases phosphorylation of the checkpoint kinases Chk1 and Chk2 and promotes caspase-dependent apoptosis, placing NOMO proteins upstream of the Chk2 checkpoint pathway in mediating chemo- and radioresistance (PMID:41151896). Beyond this single observation, which does not distinguish NOMO3 from its paralogs, no further mechanistic detail has been characterized in the available corpus.

1. 2025 Low

   To address whether NOMO proteins influence DNA-damage checkpoint signaling and cancer cell survival, knockdown was tested and showed that loss of NOMO activates Chk1/Chk2 phosphorylation and triggers caspase-dependent apoptosis, establishing NOMO upstream of the Chk2 pathway in chemo- and radioresistance.

   Evidence siRNA knockdown of NOMO proteins in lung cancer cells with antibody-array phosphoprotein profiling and apoptosis/viability assays

   PMID:41151896

   Open questions at the time

   • Single lab, single study with no independent confirmation
   • Does not isolate NOMO3's contribution from the other NOMO paralogs
   • No direct molecular mechanism linking NOMO3 to Chk2 regulation, and no structural or reconstitution data

• The direct molecular function of NOMO3, its physical partners, subcellular localization, and any paralog-specific role distinct from NOMO1/NOMO2 remain undefined in the available corpus.
• No biochemical activity or substrate identified for NOMO3
• No reciprocal validation of how NOMO3 connects to checkpoint kinase activation
• No localization or complex membership data specific to NOMO3