TIGIT as a Novel Prognostic Marker for Immune Infiltration in Invasive Breast Cancer.

Background: To assess the levels and potential therapeutic and prognostic significance of TIGIT in invasive breast cancer.

Methods: The Cancer Genome Atlas database was used to evaluate TIGIT levels in invasive breast cancer and its association with clinicopathological features. Immunohistochemistry (IHC) was performed to validate it. Further, the Kaplan-Meier survival curve, univariate and multivariate Cox regression models were applied in analyzing the role of TIGIT in the prognosis of invasive breast cancer. Go / KEGG enrichment analyses techniques were used to investigate the possible cellular mechanism, and string database was used to explore TIGIT-related proteins. Finally, the TIMER database was used to determine the association between TIGIT and immune cell infiltrations.

Results: TIGIT was differentially expressed in Pan cancer tissues compared with normal tissues. Relative to normal tissues, TIGIT levels in invasive breast cancer were elevated (p<0.05). TIGIT mRNA level was significantly different from T stage, age, ER and PR level (p<0.05). The high levels of TIGIT exhibited positive correlations with PFI and OS (p<0.05). Univariate analysis revealed that age, clinical stage, high TNM stage, menopausal status and radiotherapy were the factors affecting OS (p< 0.05). Multivariate analysis revealed that age, high clinical stage and menopausal status were independent risk factors for tumor progression (p<0.05). CD226, INPP5D, PVR, PVRL2 and PVRL3 proteins interact with TIGIT. The TIGIT levels were significantly correlated with infiltrations of immune cells (such as CD8+ T cells) (r=0.917, p<0.05).

Conclusion: TIGIT is elevated in invasive breast tumor and is closely associated with the prognosis of invasive breast cancer. TIGIT may be the target of immunotherapy for invasive breast cancer.