Clinical Performance of Friend Leukemia Virus Integration 1 Methylation as a Biomarker for Colorectal Carcinoma

Abstract

Objectives Accumulating evidence supports the reliability of molecular biomarkers and cancer, the current situation is lacking. This present study was aimed to investigate clinical performance of friend leukemia virus integration 1 (FLI1) methylation as a biomarker for colorectal cancer (CRC). Methods The datasets of UALCAN, GEPIA, cBioPortal, STRING, TIMER2.0, GEO, and KOBAS were utilized in this present study. In order to testify the methylation function of FLI1 in CRC, we studied 6 CRC cell lines and 20 pairs of tumor tissues. The transcriptional levels of FLI1 were tested by reverse transcription PCR quantitatively and western blot. Cell viability, transwell assays and plate clone assay were utilized to assess the cell function. Results FLI1 was up-regulated in the GBM, KIRC, LAML, etc. Meanwhile, it was down-regulated in BLCA, BRCA, CESC, etc (p<0.05). The CPTAC dataset showed higher total protein in the primary tissues of KIRC, lower protein in the BRCA, OV, LUAD, UCEC than normal tissues(p<0.05). Highly expressed FLI1 was linked to poor prognosis of overall survival (OS) in LGG, UVM (p<0.05). Low expression of FLI1 was associated with short OS in KIRC, LUAD, SKCM (p<0.05). Compared with normal tissues, the methylation level of FLI1 was increased in BRCA, CESC, CHOL, COAD, etc (p<0.05). In the contrary, it was decreased in KIRP, PCPG obviously (p<0.05). Moreover, it showed a reduced phosphorylation for selected probes (BRCA: NP_002008.2:S39, NP_002008.2:S3241; OV: NP_002008.2:S39; LUAD: NP_002008.2:S79, NP_002008.2:S3241; all p<0.05). Meanwhile, it showed an enhanced phosphorylation level of FLI1 in KIRC for selected probes (NP_002008.2:S241, p<0.05). Besides, a statistical negative correlation was found between FLI1 and Treg cells, neutrophils, monocytes, macrophages, NK cells, cancer-associated fibroblasts, and common immune checkpoint gene levels (p<0.05). Besides, in vivo experience showed that 5-Aza-2’-deoxycytidine diminished FLI1 methylation level and restored transcriptional levels (p>0.05) in CRC. In vitro experiments demonstrated that the proliferation, colony formation, invasion and migration of CRC cells were inhibited by FLI1 overexpression through FMNL1 (p<0.05). Conclusions This present study offers a comprehensive understanding of FLI1 in carcinomas with oncogenesis and immunotherapeutic implications. Moreover, FLI1 reduced the proliferation, colony formation, invasion and migration of CRC by FMNL1.