The motility of breast cancer cells is stimulated by HMGB1/RAGE interaction but the truncated form lacking the C terminus has no effect

HMGB1/RAGE is identified as a ligand-receptor pair that plays an important role in tumorogenesis. HMGB1 and RAGE levels are higher in most human tumors and their overexpression is associated with tumor progression. The causes of breast cancer are still poorly understood. One reason might be the existence of subtypes within various cellular mechanisms as hormone-dependent and hormone -independent malignant processes. We investigated the effect of HMGB1 protein and its truncated form lacking the C terminus on the RAGE expression and cell motility of breast cancer cell lines; MCF7-noninvasive, MDA-MB-231-invasive and normal breast epithelial one MCF10. The results demonstrate that the effects of HMGB1 and HMGB1∆C through RAGE association are observed exclusively for the hormone independent MDA-MB-231 cell line. The mobility of MDA-MB-231 cells was stimulated only by the full length HMGB1. Our results suggest that HMGB1/RAGE signaling should be considered as an essential process for the development of hormone independent breast cancers with great invasive potential. The truncated form plays the role of a blocking molecule that ”locks” the receptor and inactivates it. This makes the tailless molecule a promising therapeutic agent that competes for the biologically active HMGB1 ligand and prevents the downstream signaling through RAGE

The DNA Binding and Bending Activities of Truncated Tail-less HMGB1 protein are Differentially Affected by Lys-2 and Lys-81 Residues and Their Acetylation

The role of lysines 2 and 81 as target sites for acetylation in full-length HMGB1 and truncated tail-less protein, respectively, has been studied by mutation analysis for the abilities of these proteins to bind and bend DNA. The DNA bending ability of truncated tail-less HMGB1 containing Lys-2 mutated to alanine does not differ from that of the wild-type protein, while the same mutation of Lys-81 reduced the bending capacity of the mutant protein. These data demonstrate that Lys-81 is critical for the DNA bending ability of truncated HMGB1. Such a conclusion is further confirmed by the experiments carried out with CBP-acetylated proteins: acetylation of Lys-2 in mutant protein K81/A81 alleviated DNA bending and induced DNA end-joining. On the contrary, the acetylation of Lys-81 in the mutant K2/A2 enhanced the bending potential of HMGB1&#8710;C. Regarding the ability of HMGB1 to specifically bind bent DNA, the individual mutations of either K2 or K81 as well as the double mutation of both residues to alanine were found to completely abolish binding of truncated tail-less HMGB1 to cisplatin-modified DNA. We conclude that unlike the case with the bending ability of truncated HMGB1, where Lys-81 has a primary function, Lys-2 and Lys-81 are both critical for the protein's binding to cisplatin-modified DNA. The mutation K2/A2 in full-length HMGB1 and acidic tail removal induce the same conformational changes. Any further substitutions at the acetylable lysines in the truncated form of HMGB1 do not have an additional effect.</p

Cellular Pharmacology of Palladinum(III) Hematoporphyrin IX Complexes: Solution Stability, Antineoplastic and Apoptogenic Activity, DNA Binding, and Processing of DNA-Adducts

Two paramagnetic PdIII complexes of hematoporphyrin IX ((7,12-bis(1-hydroxyethyl)-3,8,13,17-tetramethyl-21H-23H-porphyn-2,18-dipropionic acid), Hp), namely a dinuclear one [PdIII2(Hp-3H)Cl3(H2O)5]&middot;2PdCl2, Pd1 and a mononuclear metalloporphyrin type [PdIII(Hp-2H)Cl(H2O)]&middot;H2O, Pd2 have been synthesized reproducibly and isolated as neutral compounds at different reaction conditions. Their structure and solution stability have been assayed by UV/Vis and EPR spectroscopy. The compounds researched have shown in vitro cell growth inhibitory effects at micromolar concentration against a panel of human tumor cell lines. A DNA fragmentation test in the HL-60 cell line has indicated that Pd1 causes comparable proapoptotic effects with regard to cisplatin but at substantially higher concentrations. Pd1 and cisplatin form intra-strand guanine bis-adducts as the palladium complex is less capable of forming DNA adducts. This demonstrates its cisplatin-dissimilar pharmacological profile. The test for efficient removal of DNA-adducts by the NER synthesis after modification of pBS plasmids with either cisplatin or Pd1 has manifested that the lesions induced by cisplatin are far better recognized and repaired compared those of Pd1. The study on the recognition and binding of the HMGB-1 protein to cisplatin or Pd1 modified DNA probes have shown that HMG proteins are less involved in the palladium agent cytotoxicity

High mobility group box 1 protein (HMGB1) stimulates the nuclear accumulation of p53

p53 is usually regarded as a tumour suppressor protein but its constant activation may result in pro-tumorigenic inflammation. The activation of p53 can be provoked by an increase in its concentration as a result of high level transcription, by transformation of the p53 protein to an active conformation or by its translocation from the cytoplasm to the nucleus. p53 can be activated by a wide variety of stress signals that a cell might encounter during malignant progression, such as genotoxic damage, oncogene activation and hypoxia. We found that the HMGB1 protein can play the role of a signal molecule that provokes the accumulation of p53 in the nucleus. Only the full-length protein stimulated the translocation of p53 from the cytosol to the nucleus and the effect was considerably strong and almost equal to that generated by the positive control actinomycin D. The truncated tail less form of HMGB1 was not functional. This supported the hypothesis that the C terminus plays an important role in regulating the properties of HMGB1

In Vitro Anticancer Activity of Two Ferrocene-Containing Camphor Sulfonamides as Promising Agents against Lung Cancer Cells

The successful design of antitumour drugs often combines in one molecule different biologically active subunits that can affect various regulatory pathways in the cell and thus achieve higher efficacy. Two ferrocene derivatives, DK-164 and CC-78, with different residues were tested for cytotoxic potential on non-small lung cancer cell lines, A549 and H1299, and non-cancerous MRC5. DK-164 demonstrated remarkable selectivity toward cancer cells and more pronounced cytotoxicity against A549. The cytotoxicity of CC-78 toward H1299 was even higher than that of the well-established anticancer drugs cisplatin and tamoxifen, but it did not reveal any noticeable selective effect. DK-164 showed predominantly pro-apoptotic activity in non-small cell lung carcinoma (NSCLC) cells, while CC-78 caused accidental cell death with features characteristic of necrosis. The level of induced autophagy was similar for both substances in cancer cells. DK-164 treatment of A549, H1299, and MRC5 cells for 48 h significantly increased the fluorescence signal of the NFkB (nuclear factor ‘kappa-light-chain-enhancer’ of activated B-cells) protein in the nucleus in all three cell lines, while CC-78 did not provoke NFkB translocation in any of the tested cell lines. Both compounds caused a significant transfer of the p53 protein in the nucleus of A549 cells but not in non-cancerous MRC5 cells. In A549, DK-164 generated oxidative stress close to the positive control after 48 h, while CC-78 had a moderate effect on the cellular redox status. In the non-cancerous cells, MRC5, both compounds produced ROS similar to the positive control for the same incubation period. The different results related to the cytotoxic potential of DK-164 and CC-78 associated with the examined cellular mechanisms induced in lung cancer cells might be used to conclude the specific functions of the various functional groups in the ferrocene compounds, which can offer new perspectives for the design of antitumour drugs