HMGB1, the Next Predictor of Transcatheter Arterial Chemoembolization for Liver Metastasis of Colorectal Cancer?

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions. Copyright © 2014 Elsevier Ltd. All rights reserved.

The immune system has evolved to respond not only to pathogens, but also to signals released from dying cells. Cell death through necrosis induces inflammation, whereas apoptotic cell death provides an important signal for tolerance induction. High mobility group box 1 (HMGB1) is a DNA-binding nuclear protein, released actively following cytokine stimulation as well as passively during cell death; it is the prototypic damage-associated molecular pattern (DAMP) molecule and has been implicated in several inflammatory disorders. HMGB1 can associate with other molecules, including TLR ligands and cytokines, and activates cells through the differential engagement of multiple surface receptors including TLR2, TLR4, and RAGE. RAGE is a multiligand receptor that binds structurally diverse molecules, including not only HMGB1, but also S100 family members and amyloid-beta. RAGE activation has been implicated in sterile inflammation as well as in cancer, diabetes, and Alzheimer's disease. While HMGB1 through interactions with TLRs may also be important, this review focuses on the role of the HMGB1-RAGE axis in inflammation and cancer.

Hepatocellular carcinoma (HCC)-closely associated with liver cirrhosis and, in fact, the main cause of death in patients with such disease-is now recognized as one of the most-prevalent and lethal neoplasms worldwide. Prognosis and allocation of the multiple available treatment options for patients with HCC are influenced not only by tumour stage, but also by the degree of liver-function impairment. Therefore, accurate assessment and classification of disease is important for patient management. According to the Barcelona Clinic Liver Cancer (BCLC) algorithm, intermediate-stage HCC is defined as extensive multifocal disease without vascular invasion in patients with preserved liver function and absence of cancer-related symptoms; in this context, transarterial chemoembolization (TACE) is considered the standard treatment. The use of drug-eluting beads has enabled standardization of this procedure, resulting in higher reproducibility and tolerability of the treatment. Nevertheless, not all patients with intermediate-stage HCC are good candidates for TACE and, for such patients in whom TACE is not appropriate or has failed, other treatments can be considered, including sorafenib. Radioembolization is a promising alternative that deserves further prospective studies. Herein, we review the current approaches used to accurately stratify patients with intermediate-stage HCC and subsequently allocate the most-appropriate treatments. The key developments in therapeutic strategies are also discussed.