Downregulation of high mobility group protein box-1 resensitizes ovarian cancer cells to carboplatin

HMGB1 enhances the migratory and invasive abilities of A2780/DDP cells by facilitating epithelial to mesenchymal transition via GSK‑3β

The aim of the present study was to investigate the impact and mechanism of high mobility group box 1 (HMGB1) on the regulation of cell migration and invasion in A2780/DDP cisplatin-resistant ovarian cancer cells. After transfecting small interfering (si)RNA-HMGB1 into A2780/DDP cells, Transwell migration and invasion assays were conducted to assess alterations in the cell migratory and invasive abilities. Additionally, western blotting analyses were performed to examine changes in HMGB1, phosphorylated (p)-GSK-3β, GSK-3β, E-cadherin and vimentin expression levels. The results of the present study demonstrated that the migratory and invasive abilities of A2780/DDP cells were significantly higher compared with those of A2780 cells. Additionally, the expression levels of HMGB1, p-GSK-3β and the mesenchymal phenotype marker, vimentin, in A2780/DDP cells were significantly elevated relative to the levels in A2780 cells. Conversely, the expression level of the epithelial phenotype marker, E-cadherin, was markedly decreased compared with that in A2780 cells. Following transfection of A2780/DDP cells with siRNA-HMGB1, there was a significant reduction in the rate of cell migration and invasion. Simultaneously, the expression levels of HMGB1, p-GSK-3β and vimentin were downregulated while the level of E-cadherin was upregulated. It was therefore concluded that the high expression of HMGB1 in A2780/DDP cells enhanced the cell migration and invasion abilities by facilitating epithelial to mesenchymal transition via GSK-3β.

Triarylphosphine-Coordinated Bipyridyl Ru(II) Complexes Induce Mitochondrial Dysfunction

While cancer cells rely heavily upon glycolysis to meet their energetic needs, reducing the importance of mitochondrial oxidative respiration processes, more recent studies have shown that their mitochondria still play an active role in the bioenergetics of metastases. This feature, in combination with the regulatory role of mitochondria in cell death, has made this organelle an attractive anticancer target. Here, we report the synthesis and biological characterization of triarylphosphine-containing bipyridyl ruthenium (Ru(II)) compounds and found distinct differences as a function of the substituents on the bipyridine and phosphine ligands. 4,4'-Dimethylbipyridyl-substituted compound 3 exhibited especially high depolarizing capabilities, and this depolarization was selective for the mitochondrial membrane and occurred within minutes of treatment in cancer cells. The Ru(II) complex 3 exhibited an 8-fold increase in depolarized mitochondrial membranes, as determined by flow cytometry, which compares favorably to the 2-fold increase observed by carbonyl cyanide chlorophenylhydrazone (CCCP), a proton ionophore that shuttles protons across membranes, depositing them into the mitochondrial matrix. Fluorination of the triphenylphosphine ligand provided a scaffold that maintained potency against a range of cancer cells but avoided inducing toxicity in zebrafish embryos at higher concentrations, displaying the potential of these Ru(II) compounds for anticancer applications. This study provides essential information regarding the role of ancillary ligands for the anticancer activity of Ru(II) coordination compounds that induce mitochondrial dysfunction.

The HMGB1-2 Ovarian Cancer Interactome. The Role of HMGB Proteins and Their Interacting Partners MIEN1 and NOP53 in Ovary Cancer and Drug-Response

High mobility group box B (HMGB) proteins are overexpressed in different types of cancers such as epithelial ovarian cancers (EOC). We have determined the first interactome of HMGB1 and HMGB2 in epithelial ovarian cancer (the EOC-HMGB interactome). Libraries from the SKOV-3 cell line and a primary transitional cell carcinoma (TCC) ovarian tumor were tested by the Yeast Two Hybrid (Y2H) approach. The interactome reveals proteins that are related to cancer hallmarks and their expression is altered in EOC. Moreover, some of these proteins have been associated to survival and prognosis of patients. The interaction of MIEN1 and NOP53 with HMGB2 has been validated by co-immunoprecipitation in SKOV-3 and PEO1 cell lines. SKOV-3 cells were treated with different anti-tumoral drugs to evaluate changes in HMGB1, HMGB2, MIEN1 and NOP53 gene expression. Results show that combined treatment of paclitaxel and carboplatin induces a stronger down-regulation of these genes in comparison to individual treatments. Individual treatment with paclitaxel or olaparib up-regulates NOP53, which is expressed at lower levels in EOC than in non-cancerous cells. On the other hand, bevacizumab diminishes the expression of HMGB2 and NOP53. This study also shows that silencing of these genes affects cell-viability after drug exposure. HMGB1 silencing causes loss of response to paclitaxel, whereas silencing of HMGB2 slightly increases sensitivity to olaparib. Silencing of either HMGB1 or HMGB2 increases sensitivity to carboplatin. Lastly, a moderate loss of response to bevacizumab is observed when NOP53 is silenced.

HMGB1 protein as a novel target for cancer

Highly conserved nuclear protein High Mobility Group Box1 (HMGB1) present in mammals has functionality as an immuno-modulator in the form of cytokine molecule, as a nuclear factor to regulate these molecules and DNA structural determination. It has proximal homologous DNA binding domains Box-A, Box-B and distal C-terminal domain. Reduced form exists in basic condition has chemotaxis activity, while form with disulphide bond reduced at 106th cysteine showed cytokine activity. The oxidized form is devoid of both activities. HMGB1 binds and bends dsDNA and also activates genes for secretion of inflammatory cytokines such as IL-1β, TNF-α, IL-6 and IL-18. It can interact with transcription factors Rel/NF-κB and p53 responsible for up-regulating oncogenes. Oxidative stressed injured tissues actively secrete HMGB1 outside cells to necrotize other nearby tissues passively in cytosol. Acetylation of HMGB1 weakens its binding with DNA, and promotes its migration to different tissues leading to secretion of inflammatory-cytokines. HMGB1 expression has been found very important in the genesis and promotion of different cancer by promoting metastasis. In current article, we emphasized on condition based structural variability of HMGB1, mechanism of release, physiological functions and its functionality as a biomarker for cancer to be targeted to curb cancer genesis and progression.