Extracellular Vesicle-Transported Long Non-Coding RNA (LncRNA) X Inactive-Specific Transcript (XIST) in Serum is a Potential Novel Biomarker for Colorectal Cancer Diagnosis

BACKGROUND: Colorectal cancer (CRC) cell-derived extracellular vesicles (EVs) contribute to tumor progression. Differentially expressed long non-coding (lnc)RNAs may serve as biomarkers for CRC diagnosis. This study aimed to discuss the diagnostic value of serum EV-derived lncRNA X inactive-specific transcript (XIST) in CRC. MATERIAL/METHODS: Serum EVs were extracted and identified. Microarray analysis was performed to screen out the differentially expressed lncRNAs in serum EVs. The expression and diagnostic efficacy of the most differentially expressed lncRNA were measured. Kaplan-Meier survival analysis was performed to evaluate the association between survival time and XIST expression in EVs. The expression profile of serum EV-carried XIST in 94 CRC patients with different tumor-node-metastasis stages, lymph node metastasis, and differentiation was assessed. The serum contents of CEA, CA242, CA199, and CA153 were measured. RESULTS: XIST in serum EVs in CRC patients was upregulated, with greatest diagnostic value. CRC patients with higher expression of XIST in serum EVs had worse 5-year survival rates and shorter life cycles, lower differentiation, higher lymph node metastasis, and tumor-node-metastasis than patients with lower XIST expression. XIST expression in serum EVs was positively correlated with CRC marker contents. CONCLUSIONS: XIST upregulation in serum EVs is related to CRC progression, which may be helpful to the clinical diagnosis and prognosis of CRC.