COPZ1 depletion induces cell death through different mechanisms in in vitro murine models of thyroid cancer.

OBJECTIVE: In the past years, the discovery of non-oncogene addiction (NOA) has expanded the cancer targets repertoire. In particular, novel strategies are aimed at counteracting the dependency of cancer cells on normal genes that are essential to sustain their stress phenotype. Of the NOA genes, discovered by our group, that are essential for human thyroid cancer cells, we extensively focused on COPZ1, a subunit of coatomer complex I. We previously reported that in in vitro human thyroid cancer models, COPZ1 depletion can induce IFN-I-mediated stimulatory effects, which culminates in immunogenic cell death. To evaluate in vivo the effects of COPZ1 depletion on immunity and inflammation, generation of syngeneic mouse models is needed. Toward this aim, in this work, we studied in vitro the dependency on COPZ1 in murine thyroid cancer cell lines.

METHODS: Cell viability was assessed through crystal violet assay and a commercially available kit. qRT-PCR and western blot were used to evaluate the expression of genes and proteins of interest; commercially available kits were used for monitoring cytokine release and oxidative status.

RESULTS: Analogous to the human counterpart, COPZ1 silencing impaired cell proliferation and induced ER stress in four cell lines. The transcription and secretory IFN-I-related program was activated in two of the four cell lines. In the other two cell lines, we detected an increase in ROS production, lipid peroxidation, and Ca2+ levels.

CONCLUSION: Activation of inflammatory effects after COPZ1 silencing is cell line-dependent.