C6orf15 is a novel marker of lymph node metastasis in colorectal cancer Travel Award

Introduction
Lymph node metastasis (LNM) in colorectal cancer (CRC) is associated with poor prognosis, yet its molecular drivers remain unclear. This study aims to identify novel targets contributing to LNM.
Methods
TCGA data categorized colon cancers into two groups and their transcriptomic data were analyzed using GSEA and RNAseq. Knockout (KO) of C6Orf15 in HCT116 and SW480 cell lines was performed using CRISPR-Cas9 and validated via Sanger sequencing and Western blot. The effects of C6Orf15 KO were examined using Western blot, proliferation, migration and invasion assays.
Results
TCGA analysis identified median colon cancer size of 5.375cm, allowing categorization of 'expanding' (>5cm, no lymph node involvement) and 'metastatic' (<=5cm, lymph node involvement) phenotypes. Kaplan-Meier analysis showed poorer survival in 'metastatic' group (p=0.0145). GSEA identified epithelial-mesenchymal transition (EMT) as the most enriched Hallmark in 'metastatic' tumors (NES=1.81, FDR q-value=0), with C6Orf15 among the top differentially expressed genes (LogFC=2.37, p=2.06E-07). C6Orf15 KO was performed in two cancer cell lines. RNAseq confirmed EMT downregulation in KO cells (NES=-1.44, FDR q-value=0.1). Western blot revealed unchanged CDH1, CDH2 levels but reduced SNAI1, SNAI2 expression in KO cells, suggesting partial EMT suppression. KO cells showed slower proliferation, as well as reduced migration, and invasion compared to wild-type cells.
Conclusion
C6Orf15 contributes to EMT and metastatic progression in CRC. Further studies on its molecular mechanisms could advance targeted therapies, leading to less aggressive CRC and improved patient survival.