The role of roasting in cold brew coffee chemistry is poorly understood. The brewing temperature influences extraction processes and may have varying effects across the roast spectrum. To understand the relationship between brew temperature and roast temperature, hot and cold brew coffees were prepared from Arabica Columbian coffee beans roasted to light, medium, and dark levels. Chemical and physical parameters were measured to investigate the relationships among degree of roast, water temperature, and key characteristics of resulting coffees. Cold brew coffees showed differential extraction marked by decreased acidity, lower concentration of browned compounds, and fewer TDS indicating that cold water brewing extracts some compounds less effectively than hot water brewing. Compounds in coffee did exhibit sensitivity to degree of roast, with darker roasts resulting in decreased concentrations for both hot and cold brew coffees. Total antioxidant capacity (TAC) was only sensitive to degree of roast in cold brew coffees, while hot brew coffees had a constant TAC for all three roast levels. This indicates that the solid bean matrix and its chemical constituents interact with cold water differently than with hot water. Surface wetting, pore dynamics, and solubility all contribute to the extraction potential during brewing and are all functions of water temperature.

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Overexpression of negative elongation factor E (NELF-E), a subunit of the negative elongation factor (NELF) complex involved in transcription pausing, has been implicated in poor hepatocellular carcinoma (HCC) outcome. We recently discovered an intronic heterozygous single nucleotide polymorphism (SNP), rs79208225 (G>A), near a spliceosome binding site in less than 1% of the general population but ~4% of our HCC cohort. HCC patients with the SNP had significantly longer times till recurrence (p=0.001) and better overall survival (p=0.02) compared to patients without the SNP. Using the minigene assay, we found the SNP causes exon 10 exclusion, which resulted in lower levels of full length NELF-E and the presence of a truncated NELF-E isoform that was not degraded via RNAi surveillance. We hypothesize NELF-E isoform switching is anti-tumorigenic in HCC. To investigate the effects of exon 10 exclusion, we employed antisense oligonucleotides (ASOs). HCC cells treated with ASOs had decreased cell proliferation and colony formation. Moreover, exon 10 exclusion enriched for the truncated NELF-E isoform and decreased full length mRNA and protein expression. Genetic models (CRISPR/cas9) showed similar phenotypes, suggesting that the truncated NELF-E is anti-tumorigenic. Currently, we are investigating the functional role of the truncated NELF-E protein in transcription regulation and the effects of isoform switching in HCC cells as a potential therapeutic strategy for HCCs with elevated NELF-E levels. Citation Format: Laura Reynolds, Ryan Lamm, Anna Barry, Meghan Grim, Kai Zhang, Hien Dang. Exon exclusion of NELF-E produces an anti-tumorigenic truncated isoform in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1490.