Ku70 protein in hetero-trimeric complex with Ku80 and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) represents a critical component of the nonhomologous-end-joining (NHEJ), the major machinery of DSBs repair in mammalian cells. It has been previously shown that modulation of Ku70 acetylation by histone deacetylases (HDAC) inhibitors induced sensitization of cancer cells to chemotherapeutic agents. However, the effects of such modulation on the repair of Ionizing Radiation (IR)-induced DSBs and the importance of dynamic equilibrium of acetylation/deacetylation have not been studied in details. To address these questions aceto-blocking and aceto-mimicking mutants were designed by replacing Ku70 lysine residues K317, K331 and K338 with arginine and glutamine respectively via site-directed mutagenesis. Transformed human embryonic lung fibroblasts MRC5VA were transfected to create stables cells lines over-expressing Ku70 mutant proteins. Clonogenic survival and γ-H2AX foci assays were performed to study the impact of these mutants on DNA repair proficiency of MRC5VA cells in response to IR. We report here that both Ku70 aceto-blocking and aceto-mimicking mutants rendered MRC5VA cells more susceptible to IR in terms of clonogenic survival and γH2AX foci. Moreover, modelling the possible interactions and structural impact of these aceto-blocking and aceto-mimicking mutants with DNA substrate showed that mimicking acetylation/deacetylation of K331 and K338 could directly compromise KU-DNA interactions, whereas K317 may have a more subtle role via forming a salt bridge with E330 thus optimising the positioning of the helix containing both K331 and K338 residues on the DNA. Our data indicates that dynamic equilibrium of acetylation/deacetylation of Ku70 lysine residues K317, K331 and K338 is critical for optimal repair of IR-induced DSBs, and may offer a novel therapeutic approach for cancer treatment.

Micro-RNAs (MiRNAs) are a class of small non-coding RNAs that regulate cellular gene expression. MiR-155 overexpression has been implicated in many types of cancer. Besides, miR-155 appears to help tumor invasion and migration and works as a moderator of epithelial-to-mesenchymal transition (EMT). Exopolysaccharides (EPSs) are a large group of natural heterogeneous polymers of sugars with a biologically antitumor effect. Herein, we test a hypothesis that EPS might promote its anti-tumorigenic effect via regulating miR-155 expression and its target pathways. Expression of miR-155 and a panel of targeted genes were investigated by real-time PCR. In our study, we have succeeded in the extraction, purification of exopolysaccharide with great cytotoxicity to different cancer cell lines, HepG II, Caco-2, and MCF-7. We reported that EPSs have a suppression effect on the oncogenic miR-155. In conclusion, this work clarifies a new possible mechanism for the anti-tumorigenic effect of EPSs in cancer cells and provides insights into the biological pathways through which EPSs act. Moreover, it paves the way for new prospective cancer therapeutics as anti-miRNA.

Background:: Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide with a low overall survival due to high metastasis and recurrence rates. The aim of this study is to assess and compare the possible anti-neoplastic effect of capsaicin and nanoformulated capsaicin on in vitro HCC human cell line HepG2. Materials and Methods:: Capsaicin-loaded trimethyl chitosan nanoparticles (CL TMCS NPs) were synthesized by iontropic gelation of cationic TMCS with capsaicin. The synthesized nanoparticles were characterized through TEM, and zeta analyzer. Human hepatocarcinoma HepG2 cell lines were cultured and treated with 50, 75 & 100 μM of capsaicin (CAP), plain TMCS NPs and CL-NPs as well as ethanol (control) for 24h and 48h. The induced effects were investigated by flow cytometry, immunocytochemistry assay for Bcl-2, Bax, and caspase proteins and evaluating gene expression levels of Bcl-2, Bax, and MDR-1 mRNA by real-time PCR. Results:: Our results demonstrated that capsaicin- loaded NPs had the potential to significantly increase capsaicin bioactivity compared with the plain capsaicin formulation either in inducing apoptosis through altering expression of apoptotic regulators or modifying MDR-1 expression. Conclusions:: TMCs nanoparticles investigated in this study may be a good drug delivery vehicle for capsaicin. Application of capsaicin-loaded NPs in HCC management as an adjunct therapeutic approach may be a novel strategy to improve the treatment efficacy and resistance of the conventionally used chemotherapy.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and it mostly arises as a consequence of persistent chronic inflammation. Recently, NLRP3 inflammasome has caught the attention of many research groups due to its involvement in different types of cancer. However, its direct role in HCC remains elusive. Our study aimed to evaluate the role of NLRP3 inflammasome and pyroptosis in HCC and to clarify the potential mechanism by which 17β-estradiol (E2) can be used as a protective factor against HCC. NLRP3, caspase-1 (CASP1) as well as gasdermin-D (GSDMD) mRNA expression levels were assessed in human HCC tissues and adjacent non-cancerous liver tissues. Also, HepG2 HCC cells were cultured and treated with E2, followed by detection of the mRNA levels of these three genes. Our results revealed that NLRP3, CASP1, and GSDMD mRNA expressions were significantly lower in HCC tissues than in controls, and this under-expression was closely correlated with advanced HCC stages and grades. In contrast, HepG2 HCC cells displayed significantly higher expression levels of NLRP3 inflammasome components and GSDMD in the two E2-treated groups compared to the untreated group. Also, NLRP3, CASP1, and GSDMD mRNA expression levels were positively correlated with each other. This study confirmed that lack of NLRP3 inflammasome is involved in HCC progression and 17β-estradiol-induced activation of NLRP3 inflammasome may be effective in HCC treatment as it inhibited tumor cell growth and proliferation by triggering CASP1-dependent pyroptosis in HCC cells.

No abstract