Mitochondria are present in all mammalian cells except matured red blood cells. Mitochondria consist of several metabolic pathways for glucose, fatty acids, amino acids, and bioenergetic pathways for ATP synthesis, membrane potential, and reactive oxygen production. In the liver, hepatic mitochondria play a key role in hepatic steatosis because mitochondrial metabolism produces acetyl-CoA which is the building block for synthesis of lipids and cholesterol. Mitochondria inner membrane is impermeable of metabolites, reducing equivalents, and small molecules such as phosphate, and sulfate. Thus, mitochondrial shuttles and carriers function as the routes of influx and efflux of these metabolites and molecules across the inner membrane. The signal regulation of these shuttles and mitochondrial enzymes could play a key role in coordinating the mitochondrial metabolism to adapt the cytosolic part of metabolic pathways in liver metabolic stress. Intriguingly, the interaction of mitochondria protein SH3 domain-binding protein 5 (SAB/SH3BP5) and c-Jun N-terminal kinase (JNK) was found as a pivotal role in sustained activation of JNK and phosphorylated-JNK (P-JNK) mediated activation of lipogenic pathway in nutritional excess. Knockout or knockdown of SAB prevented or reversed the hepatic steatosis, inflammation, and fibrosis, and improved metabolic intolerance and energy expenditure. Moreover, blocking the SAB peptide prevents palmitic acid-induced P-JNK interaction with SAB and inhibition of mitochondrial bioenergetics, implying the P-JNK effect on mitochondrial metabolism. This review focuses on the flow of mitochondrial metabolites in metabolic stress conditions and the contribution of mitochondria and mitochondrial stress signals in hepatic steatosis.

Chronic liver diseases (CLDs), which are typically characterized by fibrogenic progression towards liver cirrhosis and related complications eventually leading to organ failure and can also lead to the development of primary liver cancers, represent a major burden for human health on a worldwide basis. Although the present knowledge on the pathogenesis of CLDs progression and primary liver cancers development has remarkably increased in the last decades, critical molecular mediators remain incompletely understood, and approved antifibrotic therapies to efficiently counteract CLDs progression and liver cancer are lacking. In the present review, this study will specifically analyse the putative contribution of SERPINB3, a member of the superfamily of serine-protease inhibitors (SERPINs), which has been shown to exert significant pro-inflammatory and pro-fibrogenic roles in progressive CLDs as well as to be involved in the development of primary liver cancers, including hepatocellular carcinoma (HCC), cholangiocarcinoma, and hepatoblastoma.

Hunting for tumoral material in body fluids, traditionally in blood, the so-called liquid biopsy is set to revolutionize the diagnosis and management of oncological patients. However, other biofluids can also be considered as alternative sources of biomarkers to provide clinically valuable information for multiple diseases. This is the case of bile, a fluid produced in the liver, stored in the gallbladder, and excreted to the duodenum, which complex composition is known to change in different pathological conditions. Remarkably, different works have demonstrated that the identification of mutations in bile cell-free DNA (cfDNA) can outperform blood analysis for the early diagnosis of biliopancreatic tumors causing biliary strictures. Here, the literature in which bile has been tested as a liquid biopsy matrix where lipids, metabolites, proteins, and cfDNA among other analytes were measured is reviewed. Moreover, the clinical situations and procedures where bile can be available, discussing the possible applications and limitations of bile analysis are summarized. The scientific relevance and clinical potential of bile harvesting, biobanking, and analysis are put forward. All this evidence supports the value of bile as a liquid biopsy matrix for the management of patients beyond cancer, and perhaps also beyond “blood, sweat, and tears”.