Hepatotoxicity is an adverse drug reaction that accounts for approximately a third of drug post-market withdrawals. Animals and other liver models used in the drug development process are expensive, not suitable for high throughput screening, possess poor durability, and lack the dynamic range of gene expression present in a fully functioning liver. These are all representative of a screening system lacking the physiological relevance of an in vitro model for human hepatocytes. The amenability of cell lines to high throughput screening, as well as their characteristic reproducibility and availability, make them excellent candidates for liver modeling. While human hepatoma cell lines are readily available, they uniformly lack the functional phenotypic of mature hepatocytes and this issue has historically limited cell line use in such modeling applications. Recent experiments suggest that certain hepatoma cell lines can be differentiated using a variety of small molecules and culturing techniques to demonstrate some of the important functions of mature hepatocytes, including drug metabolizing enzyme (DME) gene expression. Histone deacetylase inhibitors (HDACi), as well as other families of chromatin modulators, were used to potentiate the transcription of DME genes in hepatoma cell lines and this resulted in an induced state with specific activation patterns. These activations consisted of upregulations in specific cytochrome P450 family metabolizing genes, associated transcription factors and albumin. ELISAs were performed as a follow-up procedure to determine the presence of albumin, a major ubiquitous protein that is synthesized in the liver, as a marker for liver functionality. Here we present an alternative hepatotoxicity-screening model in the form of hepatocyte cell lines that retain adequate levels of DME gene expression over time.
PROJECT: Functional differentiation of human hepatoma cell lines using chromatin modulation: development of a human liver model for drug hepatotoxicity screening
Mentor: David K. Thomas, Cancer Program
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