High expression of PLAC1 in colon cancer as a predictor of poor prognosis: A study based on TCGA data

Colon cancer is one of the most common diseases in the world with both a high incidence and high mortality. PLAC1 is activated and expressed in many cancers. We aim to explore the relationship between PLAC1 expression and prognosis in colon cancer patient. The RNA-Seq expression data and clinical information of colon cancer were downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed PLAC1 was obtained by the Wilcoxon signed-rank test; the significance difference being that PLAC1 was more highly expressed in tumor rather than normal tissue (p < 0.01). Then patients were classified into high and low risk groups by different risk scores, and the Kaplan-Meier survival analysis showed that colon cancer patients with a high PLAC1 expression had a poorer prognosis than low PLAC1 expression patients (p = 0.0031). Next, in analyzing the clinical pathology associated with PLAC1 expression, logistic regression showed that PLAC1 was expressed high in stage (OR = 4.11 for I vs. IV), lymph nodes (OR = 1.73 for N0 vs. N1+), distant metastasis (OR = 2.8 for M0 vs. M1), and status (OR = 22.81 for normal vs. tumor). Univariate and multivariate cox analyses were employed to identify that PLAC1 could be regarded as an independent prognostic factor. Univariate cox analysis showed PLAC1 had a correlation to overall survival (OS) (HR: 0.46, 95% CI: 0.28-0.77, p = 0.003). Multivariate cox analysis revealed that PLAC1 (HR: 0.51, 95% CI: 0.30-0.86, p = 0.012) could be regarded as an Independent prognostic factor. We also used quantitative real-time polymerase chain reaction (qRT-PCR) to test if PLAC1 was differently expressed in cell lines. The qRT-PCR obtained the significant results that PLAC1 expressed high in colon cancer cell lines (p < 0.05). Finally, Gene Set Enrichment Analysis (GSEA) was utilized to show 14 enriched signaling pathways. Our study discovered that high expression of PLAC1 predicts poor prognosis in colon cancer patients, providing a new biomarker, which can assist physicians in finding new diagnostic and therapy methods for colon cancer.