Thrombospondin-1 triggers calreticulin expression in human mucoepidermoid carcinoma MC-3 cells via the PERK/CHOP pathway

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy, accounting for ~30% of all salivary gland malignancies; however, effective treatments for advanced-stage disease remain limited. The induction of immunogenic cell death (ICD) has emerged as a potent anti-tumor intervention for MEC. Thrombospondin-1 (TSP-1) exhibits documented anti-tumor properties in MEC; however, its capacity to drive ICD-mediated tumor suppression remains poorly understood. In the present study, the mechanistic role of TSP-1 was investigated in MC-3 cells across four experimental cohorts: Control, TSP-1, TSP-1 combined with a PERK Inhibitor (ISRIB) and TSP-1 combined with a PERK activator (CCT020312). Cellular assays, including flow cytometry, immunofluorescence and western blot analysis, revealed that TSP-1 triggered ICD at 72 h, characterized by a significant increase in calreticulin (CRT) surface exposure. Mechanistically, pharmacological inhibition of PERK attenuated the expression of the PERK/CHOP axis. Notably, while the 4 h TSP-1 monotherapy showed negligible effects on CRT, the integration of the PERK Inhibitor markedly diminished PERK/CHOP/CRT signaling. Collectively, the present data indicated that TSP-1 facilitated ICD and CRT translocation in MEC cells via the activation of the PERK/CHOP signaling cascade. These results provide a rationale for further in vivo investigations to substantiate the therapeutic potential of TSP-1-induced ICD in MEC management.