Abstract
BACKGROUND: Collagen, a primary protein component of the extracellular matrix (ECM), undergoes a notable series of alterations concomitant with the growth of the tumor. Procollagen-lysine,2-oxoglutarate 5-dioxygenase 3 (PLOD3) is involved in the synthesis of collagen and has been associated with a variety of cancers. However, it is unclear how PLOD3 functions in esophageal squamous cell carcinoma (ESCC). METHODS: Differentially expressed genes between ESCC and adjacent normal tissues were identified using proteomic and transcriptomic analyses. These genes were then subjected to survival analysis to identify prognostic markers. Immune cell infiltration in the two subgroups was evaluated. Spearman's correlation analysis was performed to examine the correlation between PLOD3 and RBM15 expression in TCGA-ESCC database. shRNA-mediated approach was used to knockdown RBM15 in ESCC cells. The effects of RBM15 knockdown on PLOD3 expression were assessed by real-time PCR and Western blot. Moreover, COX algorithm was employed to construct a prognostic signature. RESULTS: PLOD3 was found to be highly expressed in ESCC patients and correlated with a favorable prognosis. Immune cell infiltration estimation indicated tumor-infiltrating CD4+ T cell was increased in PLOD3-high group. Correlation analysis revealed that PLOD3 was associated with RBM15 and was closely related to CD4+ T cell infiltration. Moreover, loss-of-function approaches showed that depletion of RBM15 attenuated PLOD3 expression in ESCC cells. Following univariate and multivariate Cox regression analyses, PLOD3 and RBM15 were identified as a two-gene prognostic signature for ESCC. CONCLUSION: RBM15 enhances tumor-infiltrating CD4+ T Cell abundance in ESCC by regulating PLOD3. Two new independent prognostic factors, PLOD3 and RBM15, may be useful in predicting the prognosis of ESCC.