Failure to EGFR-TKI-based therapy and tumoural progression are promoted by MEOX2/GLI1-mediated epigenetic regulation of EGFR in the human lung cancer.

BACKGROUND: Mesenchyme homeobox-2 (MEOX2)-mediated regulation of glioma-associated oncogene-1 (GLI1) has been associated with poor overall survival, conferring chemoresistance in lung cancer. However, the role of MEOX2/GLI1 in resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs)-based therapy remains unexplored in human lung cancer. METHODS: Functional assays using genetic silencing strategy by short hairpin RNAs, as well as cytotoxic (tetrazolium dye MTT) and clonogenic assays, were performed to evaluate MEOX2/GLI1-induced malignancy capacity in lung cancer cells. Further analysis performed includes western blot, qPCR and ChIP-qPCR assays to identify whether MEOX2/GLI1 promote EGFR/AKT/ERK activation, as well as EGFR overexpression through epigenetic mechanisms. Finally, preclinical tumour progression in vivo and progression-free disease interval analyses in patients treated with EGFR-TKI were included. RESULTS: Overexpressed MEOX2/GLI1 in both EGFR wild-type and EGFR/KRAS-mutated lung cancer cells were detected and involved in the activation/expression of EGFR/AKT/ERK biomarkers. In addition, MEOX2/GLI1 was shown to be involved in the increased proliferation of tumour cells and resistance capacity to cisplatin, EGFR-TKIs (erlotinib and AZD9291 'osimertinib'), AZD8542-SMO, and AZD6244-MEKK1/2. In addition, we identified that MEOX2/GLI1 promote lung tumour cells progression in vivo and are clinically associated with poorer progression-free disease intervals. Finally, both MEOX2 and GLI1 were detected to be epigenetically involved in EGFR expression by reducing both repressive markers polycomb-EZH2 and histone H3K27me3, but, particularly, increasing an activated histone profile H3K27Ac/H3K4me3 at EGFR-gene enhancer-promoter sequences that probably representing a novel EGFR-TKI-based therapy resistance mechanism. CONCLUSION: MEOX2/GLI1 promote resistance to cisplatin and EGFR-TKI-based therapy in lung cancer cells, modulating EGFR/AKT/ERK signalling pathway activation, as well as inducing an aberrant epigenetic modulation of the EGFR-gene expression in human lung cancer.

IC50 Evaluation of Platinum Nanocatalysts for Cancer Treatment in Fibroblast, HeLa, and DU-145 Cell Lines.

Cancer is a major public health problem being one of the main causes of morbidity and mortality today. Recent advances in catalytic nanomedicine have offered new cancer therapies based on the administration of nanoparticles (NPs) of platinum (Pt) dispersed in catalytic mesoporous nanomaterials (titania, TiO2) with highly selective cytotoxic properties and no adverse effects. A half maximal inhibitory concentration (IC50) study was carried out in cancerous cell lines (HeLa, DU-145, and fibroblasts) to evaluate the cytotoxic effect of different nanomaterials [Pt/TiO2, TiO2, and Pt(acac)2] synthesized by the sol-gel method at concentrations 0-1000 µg/mL. The assays showed that IC50 values for Pt in functionalized TiO2 (NPt) in HeLa (53.74 ± 2.95 µg/mL) and DU-145 (75.07 ± 5.48 µg/mL) were lower than those of pure TiO2 (74.29 ± 8.95 and 82.02 ± 6.03 µg/mL, respectively). Pt(acac)2 exhibited no cytotoxicity. Normal cells (fibroblasts) treated with NPt exhibited no significant growth inhibition, suggesting the high selectivity of the compound for cancerous cells only. TiO2 and NPt were identified as antineoplastic compounds in vitro. Pt(acac)2 is not recommendable because of the low cytotoxicity observed.

Streptococcus pneumoniae requires iron for its viability and expresses two membrane proteins that bind haemoglobin and haem.

Streptococcus pneumoniae, a human pathogen bacterium, can support its growth using haemoglobin (Hb) and haem as sole iron sources, but not when holo-transferrin or holo-lactoferrin is supplied. For this reason, it is easy to think that the principal iron sources for this pathogen inside humans are Hb and haem. Unfortunately, the mechanism has been poorly studied. The findings presented in this study are the first efforts that attempted to explain the mechanism involved in iron acquisition of this pathogen. This pathogen was capable of supporting its viability when iron sources such as Hb or haem were supplied. Membranes of S. pneumoniae were separated and their respective proteins were solubilized in order to be purified by haem-affinity chromatography. This strategy allowed us to purify seven membrane proteins. An experiment of competence with haem and iron showed two potential haem and Hb-binding proteins. Their Hb-binding function was confirmed by overlay assay using Hb and their respective identities were obtained by mass spectrometry. Then by amino acid alignment analysis, the motif involved in binding of Hb or haem was revealed. These results are the first findings that attempt to explain the mechanisms developed by S. pneumoniae to acquire iron from Hb or haem in the host, which could allow a better understanding of the biology of this bacterium.

The gene frpB2 of Helicobacter pylori encodes an hemoglobin-binding protein involved in iron acquisition.

Human hemoglobin (Hb) is a metalloprotein used by pathogens as a source of iron during invasive process. It can support the Helicobacter pylori growth and several proteins are induced during iron starvation. However, the identity of those proteins remains unknown. In this work, by in silico analysis we identified FrpB2 in H. pylori genome. This protein was annotated as an iron-regulated outer membrane protein. Multiple amino acid alignment showed the motifs necessary for Hb-binding. We demonstrate the ability of FrpB2 to bind Hb by overlay experiments. In addition, the overexpression of this gene allowed the cell growth in media without free iron but supplemented with Hb. All these results support the idea that frpB2 is a gene of H. pylori involved in iron acquisition when Hb is used as a sole iron source.