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A specific cholesterol metabolic pathway is established in a subset of HCCs for tumor growth.

ABSTRACT: The liver plays a central role in cholesterol homeostasis. It exclusively receives and metabolizes oxysterols, which are important metabolites of cholesterol and are more cytotoxic than free cholesterol, from all extrahepatic tissues. Hepatocellular carcinomas (HCCs) impair certain liver functions and cause pathological alterations in many processes including cholesterol metabolism. However, the link between an altered cholesterol metabolism and HCC development is unclear. Human ACAT2 is abundantly expressed in intestine and fetal liver. Our previous studies have shown that ACAT2 is induced in certain HCC tissues. Here, by investigating tissue samples from HCC patients and HCC cell lines, we report that a specific cholesterol metabolic pathway, involving induction of ACAT2 and esterification of excess oxysterols for secretion to avoid cytotoxicity, is established in a subset of HCCs for tumor growth. Inhibiting ACAT2 leads to the intracellular accumulation of unesterified oxysterols and suppresses the growth of both HCC cell lines and their xenograft tumors. Further mechanistic studies reveal that HCC-linked promoter hypomethylation is essential for the induction of ACAT2 gene expression. We postulate that specifically blocking this HCC-established cholesterol metabolic pathway may have potential therapeutic applications for HCC patients.

SUBMITTER: Lu M

PROVIDER: S-EPMC3841111 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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A specific cholesterol metabolic pathway is established in a subset of HCCs for tumor growth.

Lu Ming M Hu Xi-Han XH Li Qin Q Xiong Ying Y Hu Guang-Jing GJ Xu Jia-Jia JJ Zhao Xiao-Nan XN Wei Xi-Xiao XX Chang Catherine C Y CC Liu Yin-Kun YK Nan Fa-Jun FJ Li Jia J Chang Ta-Yuan TY Song Bao-Liang BL Li Bo-Liang BL

Journal of molecular cell biology 20131026 6

The liver plays a central role in cholesterol homeostasis. It exclusively receives and metabolizes oxysterols, which are important metabolites of cholesterol and are more cytotoxic than free cholesterol, from all extrahepatic tissues. Hepatocellular carcinomas (HCCs) impair certain liver functions and cause pathological alterations in many processes including cholesterol metabolism. However, the link between an altered cholesterol metabolism and HCC development is unclear. Human ACAT2 is abundan ...[more]

PMID: 24163426

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Project description:To understand the organisation of the glucose regulatory system, we analysed 91 deletion mutants of established glucose signalling and metabolic pathway members in Saccharomyces cerevisiae by DNA microarrays. These deletion mutants do not induce pathway-specific transcriptional responses reflecting the tight interconnection between pathways of the glucose regulatory system. Instead, one main transcriptional response is discerned, which varies in direction to mimic either a high or a low glucose response. The study reveals both known and unknown relationships within and between individual pathways and their members. Metabolic components of the glucose regulatory system are most frequently affected at the transcriptional level. A new network approach is applied that exposes the hierarchical organisation of the glucose regulatory system. Tps2 and Tsl1, two enzymes involved in trehalose biosynthesis, are predicted to be the most downstream transcriptional components. This prediction is further validated by epistasis analysis of Tps2 double mutants. Taken together, this suggests that changes in perceived glucose levels ultimately lead to a shift in trehalose biosynthesis. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used for each separate hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Up to five deletion strains were grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.

Dataset Information

A specific cholesterol metabolic pathway is established in a subset of HCCs for tumor growth.

Publications

A specific cholesterol metabolic pathway is established in a subset of HCCs for tumor growth.

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