Comprehensive bioinformatics analysis and clinical validation of PPP1R13L in rectal adenocarcinoma.

aimsThis study aimed to elucidate the function of PPP1R13L in rectal adenocarcinoma (READ) and evaluate its potential as a serum biomarker for the disease.

methodsA range of bioinformatics tools, including Xiantao tool, UALCAN, GEPIA2, scCancerExplorer, and TISIDB, were utilized to perform an extensive analysis of PPP1R13L, focusing on its expression profile, gene promoter methylation status, transcript isoforms, immune infiltration associations, and clinical relevance in READ. We specifically analyzed gene expression across 33 cancer types using the Xiantao platform, investigated promoter methylation levels via UALCAN, and examined transcript isoform expression through GEPIA2. Immune infiltration assessments were conducted using Xiantao tools, while gene set enrichment analysis (GSEA) was employed to identify pertinent signaling pathways. Protein-protein interaction networks were constructed using STRING and further analyzed for hub genes with Cytoscape software. The relationship between PPP1R13L and immunomodulators was examined through TISIDB, and drug sensitivity was evaluated based on the GSE241101 dataset. Quantitative ELISA assays were performed to measure serum levels of PPP1R13L in samples from 108 READ patients and 62 healthy controls.

resultsOur results revealed a significant up-regulation of PPP1R13L expression in READ tissues when compared to normal tissues (p < 0.05), corroborated by data from diverse databases. Conversely, promoter methylation levels of PPP1R13L were significantly elevated in normal rectal tissues as opposed to primary tumors (p = 6.00E-04). The expression of the PPP1R13L gene demonstrated variability, with heightened expression levels correlating with advanced clinical stages and lymphatic invasion (p < 0.05). Furthermore, a positive correlation was identified between PPP1R13L expression and natural killer (NK) cells, while an inverse relationship was observed with T-helper 2 (Th2) cells. GSEA indicated that PPP1R13L is implicated in biological processes such as keratinization and immune responses. Analysis of the protein-protein interaction network showed associations between PPP1R13L and proteins such as NDUFS7, MRPL2, and NDUFA13, which are involved in mitochondrial respiratory chain pathways. Additionally, PPP1R13L expression positively correlated with immunomodulatory factors like PVRL2, TNFRSF25, and TAPBP in the context of READ. Cells exhibiting elevated PPP1R13L expression demonstrated diminished sensitivity to drugs such as Tozasertib, RO-3306-1052, OF-1_1853, and BL-2536_1086, while they showed increased sensitivity to ERK_2440_1713, ERK_6604_1714, and WZ4003_1614. The serum concentration of PPP1R13L protein in READ patients was significantly higher, measuring 260.1 ± 8.49 ng/L, compared to 235.3 ± 6.21 ng/L in the control group (P < 0.001). Notably, male patients had higher serum levels of PPP1R13L than female patients (P = 0.041). Moreover, patients in stages IIB-IIIC exhibited significantly higher levels of PPP1R13L compared to those in stages I-IIA (P = 0.028), and those with lymphatic metastasis had elevated levels relative to those without (P = 0.019). Additionally, patients with polyps presented significantly higher levels of PPP1R13L than those without polyps (P = 0.033). The area under the curve (AUC) for serum PPP1R13L protein in receiver operating characteristic (ROC) analysis was determined to be 0.986. The optimal cutoff value for diagnosing READ was established.The concentration was quantified at 249.49 ng/L.

conclusionsThe expression of PPP1R13L is significantly elevated in READ and is associated with adverse clinical outcomes and immune cell infiltration. This finding indicates that PPP1R13L has the potential to function as a significant diagnostic and prognostic biomarker for READ, underscoring the necessity for further clinical validation.