Identification of the Immune-related lncRNA SNHG14/ miR-200a-3p/ PCOLCE2 Axis in Colorectal Cancer.

CONTEXT: Procollagen C-endopeptidase enhancer 2 (PCOLCE2) is associated with the degradation of the extracellular matrix and collagen-chain trimerization, playing a yet unexplored role in tumor prognosis.

OBJECTIVE: The study intended to characterize PCOLCE2's influence on colorectal cancer (CRC) using expression analysis and to investigate its prognostic potential.

DESIGN: The research team performed a genetic analysis using genetic databases, including The Cancer Genome Atlas (TCGA), Gene Expression Profiling Interactive Analysis (GEPIA), the Tumor IMmune Estimation Resource (TIMER), and LinkedOmics.

SETTING: The study took place at Xianyang Central Hospital, Xianyang, Shaanxi Province, China.

OUTCOME MEASURES: The research team: (1) identified differentially expressed PCOLCE2; (2) determined PCOLCE2 expression in gastrointestinal neoplasm; (3) determined the relationship between PCOLCE2 expression and clinical information; (4) identified the mRNA-miRNA-lncRNA regulatory network; (5) ascertained miRNA expression regulated changes in downstream mRNA levels, that could affecting patients' overall survival (OS) and prognoses; (6) assessed the correlation between PCOLCE2 and immune cells; (7) established the relationship between PCOLCE2 and the immune checkpoint; (8) determined the correlation between PCOLCE2 and tumor purity and immune cell infiltration; (9) determined the relationship between PCOLCE2 expression and clinicopathological features; and (10) identified the pathological changes of PCOLCE2.

RESULTS: PCOLCE2 in colorectal adenocarcinoma (COAD) tissues was significantly lower than that in normal tissues (P < .05), correlating with DNA methylation and copy-number variation. Elevated PCOLCE2 levels were associated with poorer overall survival (OS), with P = 4.2e-07, and with advancing clinical stages-II, III, and IV-of the cancer (all P < .05). Furthermore, PCOLCE2 was significantly associated with the MSI phenotype and was an independent element impacting colorectal cancer's prognosis. The correlation analysis revealed positive connections between PCOLCE2 expression and immune checkpoint-linked genes-programmed cell death protein 1 (PDCD1), cytotoxic T-lymphocyte associated protein 4 (CTLA4), and cluster of differentiation 274 (CD274), all while also being negatively correlated with tumor purity (Cor=-0.223, P = 5.59E-06) and positively associated with CD8+ T cells (Cor=0.087, P = 7.87E-02), CD4+T cells (Cor=0.236, P = 1.64E-06), macrophages (Cor=0.362, p=6.06E-14), neutrophils (Cor=0.206, P = 4.28E-05), B(Cor=0.231, P = 2.95E-06).

CONCLUSIONS: The current study revealed for the first time that a novel regulatory axis-long noncoding RNA (lncRNA) small nucleolar RNA host gene 14 (SNHG14)/ miR-200a-3p/ PCOLCE2- can act as the oncogenic axis of CRC cells and that clinicians can use it to predict the OS of colon-cancer patients. Additionally, differences in the protein expression of PCOLCE2 between normal and adenocarcinoma-colorectal tissues suggest its potential as a prognostic biomarker for CRC.