# MAO-A (MAOA)

Source: https://onco.cc/targets/maoa/  
OnCo record `maoa` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MAO-A is an enzyme best known for breaking down serotonin and other signalling chemicals in the brain; medicines called MAO inhibitors, used for some neurological disorders, block it. Aggressive prostate cancers carry more of it, and a MAO-A inhibitor designed to stay out of the brain is in an early prostate cancer trial.

## Summary

MAOA (chromosome Xp11.3) is a mitochondrial enzyme that breaks down amine neurotransmitters such as serotonin, producing hydrogen peroxide (UniProt P21397). A 2014 Journal of Clinical Investigation study reported that high-grade, aggressive prostate tumours express more MAOA, that MAOA drove epithelial-to-mesenchymal transition and stabilised HIF1-alpha through reactive oxygen species, and that knocking it down reduced or eliminated prostate tumour growth and metastasis in mouse models (Wu et al., doi:10.1172/JCI70982). In OnCo, ITR-251 is a reversible MAO-A inhibitor with limited ability to cross the blood-brain barrier, in a phase 1 trial in metastatic castration-resistant prostate cancer.

## Fields

- Kind: Target
- Last checked: 2026-11-03
- Also known as: MAO-A; monoamine oxidase A
- Tags: pipeline-gap-target
- Symbol: MAOA
- Class: enzyme
- Biology: Amine oxidase that breaks down neuroactive and vasoactive amines and prefers serotonin as substrate (UniProt P21397).
- Where found: High-grade prostate cancer (raised expression, doi:10.1172/JCI70982); Metastatic castration-resistant prostate cancer (ITR-251 trial)

## Notes

- Prevalence not recorded: HGNC, UniProt and the paper cited give no positivity rate.

## Sources

- HGNC HGNC:6833: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:6833
- UniProt P21397: https://www.uniprot.org/uniprotkb/P21397/entry
- NCBI Gene 4128: https://www.ncbi.nlm.nih.gov/gene/4128
- Monoamine oxidase A mediates prostate tumorigenesis and cancer metastasis (J Clin Invest 2014): https://doi.org/10.1172/JCI70982

## Connected records

- cancers: [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- drugs: [ITR-251](https://onco.cc/drugs/itr-251/)

---
JSON: https://onco.cc/api/v1/entities/maoa.json