Original ArticleTargeting COPZ1 non-oncogene addiction counteracts the viability of thyroid tumor cells

- COPZ1 represents an example of non-oncogene addiction in thyroid tumor cells.
- COPZ1 depletion affects thyroid tumor cell viability.
- Cell death is associated with abortive autophagy, ER stress, UPR and apoptosis.
- In vivo COPZ1 depletion reduces the growth of thyroid tumor mouse xenografts.
- COPZ1 represents an attractive therapeutic target for thyroid cancer.

Thyroid carcinoma is generally associated with good prognosis, but no effective treatments are currently available for aggressive forms not cured by standard therapy. To find novel therapeutic targets for this tumor type, we had previously performed a siRNA-based functional screening to identify genes essential for sustaining the oncogenic phenotype of thyroid tumor cells, but not required to the same extent for the viability of normal cells (non-oncogene addiction paradigm). Among those, we found the coatomer protein complex ζ1 (COPZ1) gene, which is involved in intracellular traffic, autophagy and lipid homeostasis. In this paper, we investigated the mechanisms through which COPZ1 depletion leads to thyroid tumor cell death. We showed that siRNA-mediated COPZ1 depletion causes abortive autophagy, endoplasmic reticulum stress, unfolded protein response and apoptosis. Interestingly, we observed that mouse tumor xenografts, locally treated with siRNA targeting COPZ1, showed a significant reduction of tumor growth. On the whole, we demonstrated for the first time the crucial role of COPZ1 in the viability of thyroid tumor cells, suggesting that it may be considered an attractive target for novel therapeutic approaches for thyroid cancer.