Abstract C103: Exploring ethnicity-specific molecular mechanism of cholesterol and fatty acid synthesis pathway in Hispanic colorectal cancer
Authors: Roy Somrita , Nair Soumya , Islam Khan Zahirul , Roy Sourav 
Published: September 2024

Colorectal cancer (CRC) is the most prevalent gastrointestinal cancer, the third most common malignancy and the second leading cause of cancer-related mortality worldwide. The American Cancer Society (ACS) estimates 152,810 new cases of colorectal cancer, with an estimated 53,010 deaths in 2024. Typically diagnosed in older adults, CRC incidence is rising among younger individuals, particularly in Hispanics (16.5%) compared to non-Hispanic whites (8.7%). Due to the lack of timely screenings in this ethnic group, further research is crucial to identify novel biomarkers and therapeutic targets for improved early detection and intervention. To accomplish this goal, we performed RNA-sequencing of Hispanic and non-Hispanic White (NHW) CRC tissues. The transcriptomic analysis revealed differential gene expression patterns in Hispanic and NHW populations when compared to respective normal adjacent tissues (NATs). We identified 3577 differentially expressed genes (DEGs) in Hispanic CRC samples and 2971 DEGs in NHW CRC samples, of which 1831 DEGs were unique to Hispanic. Based on the preliminary analysis we hypothesized that unique DEGs from the Hispanic population could help identify potential pathways contributing to CRC progression. Among these 1831 unique DEGs, many of the genes are associated with cholesterol and fatty acid synthesis pathway. The cholesterol biosynthesis pathway is a highly diverse and interconnected signaling pathway, playing essential roles in cellular function and systemic homeostasis. Its complexity and regulatory mechanisms make it a critical area of study in cancer. Studies indicate that Hispanics and African Americans with high cholesterol tend to have higher Body mass index (BMI) levels compared to Whites which has an increased risk of colorectal cancer. However, the role of cholesterol metabolism and fatty acid metabolism in CRC have not been studied from the Hispanic health disparities perspective. From the 1831 DEGs, we selected those in the cholesterol and fatty acid synthesis pathways with significant log2 fold changes (≤ -2 or ≥ +2) and adjusted p-values (FDR ≤ 0.05). Our bioinformatics analysis identified four key DEGs: LCN2, DHCR7, PCSK9 and SQLE. The expression levels of these genes were examined in Hispanic CRC vs. NHW CRC tissue samples using qRT-PCR. Elevated expression of LCN2 and SQLE was observed in late-stage Hispanic CRC tissues compared to NHW CRC tissues, while DHCR7 exhibited high expression in early-stage Hispanic CRC. On the other hand, PCSK9 showed low expression in both early and late stages of Hispanic CRC, suggesting potential ethnicity-specific molecular signatures in CRC progression. Moving forward, protein level studies and functional analysis of these DEGs in Hispanic CRC tissues and organoids will enhance our understanding of the role of cholesterol and fatty acid synthesis pathway proteins. Thus, elucidating novel molecular mechanisms underlying CRC progression could lead to identification of potential Hispanic specific biomarkers and therapeutic targets for early diagnosis and intervention.

Citation Format: Somrita Roy, Soumya Nair, MD Zahirul Islam Khan, Sourav Roy. Exploring ethnicity-specific molecular mechanism of cholesterol and fatty acid synthesis pathway in Hispanic 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 C103.