The E3 ligase HECTD4 regulates COX-2-dependent tumor progression and metastasis
- Joanna A. Vuille
- Cem Tanriover
- Ezgi Antmen
- Douglas S. Micalizzi
- Richard Y. Ebright
- Sambhavi Animesh
- Robert Morris
- Soroush Hajizadeh
- Zachary J. Nicholson
- Hunter C. Russell
- Eric F. Zaniewski
- Ben S. Wittner
- Ben K. Wesley
- Ji Eun Kwak
- Julian Grünewald
- Regan N. Szalay
- Douglas B. Fox
- Min Yang
- J. Keith Joung
- Doga C. Gulhan
- Andrew E. H. Elia
- Wilhelm Haas
- Eugene Oh
- Shyamala Maheswaran
- Daniel A. Haber
2026-05-04
E3 ubiquitin ligases mediating turnover of proteins engaged in cancer progression point to key regulatory nodes. To uncover modifiers of metastatic competency, we conducted an in vivo genome-wide CRISPR-inactivation screen using cultured breast circulating tumor cells, following intravascular seeding and lung colonization. We identified HECTD4, a previously uncharacterized gene encoding a conserved potential homologous to E6AP C-terminus domain–containing ubiquitin transferase, as a potent tumor and metastasis suppressor. We show that purified HECTD4 mediates ubiquitin conjugation in vitro, and proteomic studies combined with ubiquitin remnant profiling identify a major degradation target as the prostaglandin synthetic enzyme cyclooxygenase-2 ( COX-2 ; PTGS2 ). In addition to COX-2 itself, HECTD4 targets its regulatory kinase MKK7. In breast cancer models, HECTD4 expression is induced as cells lose adherence to the matrix, and its depletion massively increases COX-2 expression, enhancing anchorage-independent proliferation and tumorigenesis. Genetic or pharmacologic suppression of COX-2 reverses the protumorigenic and prometastatic phenotype of HECTD4-depleted cells. Thus, HECTD4 encodes an E3 ubiquitin ligase that downregulates COX-2 suppressing anchorage independence in epithelial cancer cells.