STAT3 interactome predicts presence of proteins that regulate immune system in oral squamous cell carcinoma

Objectives: Signal transducer and activator of transcription 3 (STAT3) is one of the key proliferation mechanism–related proteins that helps in oral squamous cell carcinoma (OSCC) progression. Immune evasion by STAT3 is mediated by the JAK2/STAT3/PDL1 signaling axis. Based on previous findings, we hypothesized that STAT3-binding partners participate in the inhibition of anti-tumor activity in OSCC.

Methods: A 3D cancer-immune co-culture model was constructed using oral cancer cell lines SCC4, SCC9, SCC25, and CAL27 and normal oral cell line OKF6. The cells were co-cultured with natural killer (NK-92) and Jurkat cells. The target protein STAT3 was chosen based on SWATH data, and co-immunoprecipitation (Co-IP)-based proteomics was conducted. The Co-IP LC-MS/MS output was analysed to determine the protein interaction network, gene ontology, pathway analysis, and protein cluster annotation.

Results: STAT3 in oral cancer cell lines interacts with the epidermal growth factor receptor (EGFR) and other proteins that participate in proliferation and immune mechanisms. Proteome analysis showed that some STAT3-binding proteins found in this study are known immune system regulators.

Conclusion: Overall, STAT3 interactive proteins regulate the immune system in oral squamous cell carcinoma cells.