Abstract C094: Differential expression analysis with transcriptome data in FFPE samples from Colombian patients with colorectal cancer
Authors: Montero Ovalle Wendy J. , Serrano Gómez Silvia J , Ballen Lozano Diego F 
Published: September 2024

Abstract
Introduction: Colorectal cancer (CRC) is a significant public health issue in Colombia, It occupies third place in incidence and ranking as the fifth leading cause of cancer-related deaths. Understanding the sociodemographic, clinicopathological, and molecular characteristics of CRC patients is crucial for prognosis, effective management, and treatment. Several molecular alterations and clinicopathological variables have been associated with the prognosis of the disease in different populations; However, we do not know if there are differentially expressed genes specific to Colombian population that are associated with CRC prognosis. Objective: Perform differential expression analysis using RNA-seq data obtained from formalin-fixed paraffin-embedded (FFPE) tissue samples from Colombian patients with CRC. Methodology: For this preliminary analysis were included 5 patients diagnosed with CRC between 2010-2014 at Instituto Nacional de Cancerologia from Colombia. From each patient, formalin-fixed and paraffin-embedded (FFPE) samples of tumor tissue and non-tumor tissue from the surgical remnant were obtained. Extracted RNA was used to perform whole-genome RNA sequencing (RNA-seq) at a depth of 100X. Bioinformatic analysis was performed using Fastqc, Cutadapt, Ribodetector, and STAR on a Linux server. The DESeq2 package in RStudio was used to perform the differential expression analysis between tumor samples vs. non-tumorous. A significant differential expression was considered using an FDR-adjusted p ≤0.05 and a log fold change of 2. Results and discussion: A list of 18 differentially expressed genes was obtained which 5 underexpressed stand out: B3GNT6 (LFC:-10.66; padj=0.0093), ITLN1 (LFC:-6.23; padj=0.0231), NR3C2 (LFC:-3.34; padj=0.0231), NLGN1 (LFC:- 0.46; padj=0.0301), CEACAM7 (LFC:-5.91; padj= 0.0301); and one overexpressed gene: RPL9 (LFC:5.44; padj=0.0267). These genes have been previously characterized and associated with the progression and prognosis of this disease in other populations. Conclusions: 6 differentially expressed genes were found using RNA-seq in FFPE samples. These genes have been associated with CRC progression and prognosis in previous studies, but have not been evaluated in the Colombian population. From this perspective, we propose to continue with the analysis by increasing the number of samples and evaluating their association with the different clinicopathological variables and their impact on the prognosis of the disease.
Citation Format: Wendy J. Montero Ovalle, Silvia J Serrano Gómez, Diego F Ballen Lozano. Differential expression analysis with transcriptome data in FFPE samples from Colombian patients with colorectal cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C094.