Bcl2-low-expressing MCF7 cells undergo necrosis rather than apoptosis upon staurosporine treatment

Pivotal role of human stearoyl-CoA desaturases (SCD1 and 5) in breast cancer progression: oleic acid-based effect of SCD1 on cell migration and a novel pro-cell survival role for SCD5

The influence of cell membrane fluidity on cancer progression has been established in different solid tumors. We previously reported that “cancer-associated fibroblasts” (CAFs) induced epithelial-mesenchymal transition and increased cell membrane fluidity and migration in poorly (MCF-7) and highly invasive (MDA-MB-231) breast cancer cells. We also found that the membrane fluidity regulating enzyme stearoyl-CoA desaturase 1 (SCD1) was upregulated in tumor cells co-cultured with CAFs and established its essential role for both intrinsic and CAF-driven tumor cell motility. Here, we further explored the mechanisms involved in the SCD1-based modulation of breast cancer cell migration and investigated the role of the other human SCD isoform, SCD5. We showed that the addition of oleic acid, the main SCD1 product, nullified the inhibitory effects produced on MCF-7 and MDA-MB-231 cell migration by SCD1 depletion (pharmacological or siRNA-based). Conversely, SCD5 seemed not involved in the regulation of cancer cell motility. Interestingly, a clear induction of necrosis was observed as a result of the depletion of SCD5 in MCF-7 cells, where the expression of SCD5 was found to be upregulated by CAFs. The necrotic effect was rescued by a 48-h treatment of cells with oleic acid. These results provide further insights in understanding the role of SCD1 in both intrinsic and CAF-stimulated mammary tumor cell migration, unveiling the metabolic basis of this desaturase-triggered effect. Moreover, our data suggest the ability of CAFs to promote the maintenance of tumor cell survival by the induction of SCD5 levels.

Attenuated heme oxygenase-1 responses predispose the elderly to pulmonary nontuberculous mycobacterial infections

Pulmonary infections with nontuberculous mycobacteria (P-NTM), such as by Mycobacterium avium complex (M. avium), are increasingly found in the elderly, but the underlying mechanisms are unclear. Recent studies suggest that adaptive immunity is necessary, but not sufficient, for host defense against mycobacteria. Heme oxygenase-1 (HO-1) has been recognized as a critical modulator of granuloma formation and programmed cell death in mycobacterial infections. Old mice (18-21 mo) infected with M. avium had attenuated HO-1 response with diffuse inflammation, high burden of mycobacteria, poor granuloma formation, and decreased survival (45%), while young mice (4-6 mo) showed tight, well-defined granuloma, increased HO-1 expression, and increased survival (95%). To further test the role of HO-1 in increased susceptibility to P-NTM infections in the elderly, we used old and young HO-1^+/+ and HO-1^-/- mice. The transcriptional modulation of the JAK/STAT signaling pathway in HO-1^-/- mice due to M. avium infection demonstrated similarities to infected wild-type old mice with upregulation of SOCS3 and inhibition of Bcl2. Higher expression of SOCS3 with downregulation of Bcl2 resulted in higher macrophage death via cellular necrosis. Finally, peripheral blood monocytes (PBMCs) from elderly patients with P-NTM also demonstrated attenuated HO-1 responses after M. avium stimulation and increased cell death due to cellular necrosis (9.69% ± 2.02) compared with apoptosis (4.75% ± 0.98). The augmented risk for P-NTM in the elderly is due, in part, to attenuated HO-1 responses, subsequent upregulation of SOCS3, and inhibition of Bcl2, leading to programmed cell death of macrophages, and sustained infection.

In vitro anticancer effect of venom from Cuban scorpion Rhopalurus junceus against a panel of human cancer cell lines

In Cuba the endemic species of scorpion Rhopalurus junceus has been used in traditional medicine for cancer treatment. However, there is little scientific evidence about its potential in cancer therapy. The effect of a range of scorpion venom concentrations (0.1, 0.25, 0.5, 0.75 and 1mg/ml) against a panel of human tumor cell lines from epithelial (Hela, SiHa, Hep-2, NCI-H292, A549, MDA-MB-231, MDA-MB-468, HT-29), hematopoietic origins (U937, K562, Raji) and normal cells (MRC-5, MDCK, Vero) was determined by the MTT assay. Additionally, the effect of venom on tumor cell death was assayed by Fluorescence microscopy, RT-PCR and western blot. Only the epithelial cancer cells showed significant cell viability reduction, with medium cytotoxic concentration (IC50) ranging from 0.6-1mg/ml, in a concentration-dependent manner. There was no effect on either normal or hematopoietic tumor cells. Scorpion venom demonstrated to induce apoptosis in less sensitive tumor cells (Hela) as evidenced by chromatin condensation, over expression of p53 and bax mRNA, down expression of bcl-2 mRNA and increase of activated caspases 3, 8, 9. In most sensitive tumor cells (A549), scorpion venom induced necrosis evidenced by acridine orange/ethidium bromide fluorescent dyes and down-expression of apoptosis-related genes. We concluded the scorpion venom from R. junceus possessed a selective and differential toxicity against epithelial cancer cells. This is the first report related to biological effect of R. junceus venom against a panel of tumor cells lines. All these results make R. junceus venom as a promise natural product for cancer treatment.

A computational approach to predict suitable target sites for trans-acting minimal hammerhead ribozymes

Trans-acting hammerhead ribozymes are challenging tools for diagnostic, therapeutic, and biosensoristic purposes, owing to their specificity, efficiency, and great flexibility of use. One of the main problems in their application is related to the difficulties in the design of active molecules and identification of suitable target sites.The aim of this chapter is to describe ALADDIN, "SeArch computing tooL for hAmmerheaD ribozyme DesIgN," an open-access tool able to automatically identify suitable cleavage sites and provide a set of hammerhead ribozymes putatively active against the selected target.ALADDIN is a fast, cheap, helpful, and accurate tool designed to overcome the problems in the design of trans-acting minimal hammerhead ribozymes.

Hammerhead ribozymes in therapeutic target discovery and validation

Gene function assessment is a main task in biological networking investigations and system biology. High throughput technologies provide an impressive body of data that enables the design of hypotheses linking genes to phenotypes. When a putative scenario is depicted, gene knockdown technologies and RNA-dependent gene silencing are the most frequent approaches to assess the role of key effectors. In this paper, we discuss the relevance of hammerhead ribozymes in target discovery and validation, describing their properties and applications and highlighting their selectivity. In particular, similarities with siRNAs are presented and advantages and drawbacks are discussed. A description of the perspectives of ribozyme application in wide range studies is also provided, strengthening the value of these inhibitors for target validation purposes.

Facilitated in vivo synthesis of ribonucleic acid and protein via T7 RNA polymerase

Ribozyme and small interfering RNA (siRNA) now are widely used to suppress target genes bearing homologous sequences. In this study, commonly used cell lines (e.g., HEK, HeLa, H1299) were stably transfected with gene encoding T7 RNA polymerase. The cytoplasm-restricted transcription activity of T7 RNA polymerase confers a continuous and robust transcription from T7 promoter-containing oligonucleotide (ODN) template for siRNA or ribozyme and leads to 70 to 80% inhibition of the tested target genes. ODN template offers the advantages of being more stable and economical than synthetic or in vitro-transcribed siRNA or ribozyme. Compared with the use of siRNA/ribozyme-expressing plasmids, our system does not require procedures with preparations of recombinant plasmids and enrichment of transfected cells and can be applied to synthesize protein in which different levels of translation could be modulated via variations in the presence of polyA tail or internal ribosome entry site (IRES) in the T7-transcribed RNAs. The results of our current study provide a rapid and efficient system for the assay of in vivo synthesis and expression of RNAs and proteins.

Breast cancer proteomics: clinical perspectives

Breast cancer is the one of leading causes of cancer-related deaths in women within economically developed regions of the world. A major focus of present research into this malignancy is the identification of new biomarkers and drug targets to improve detection and treatment. Proteomics represents one of the latest technological developments in this context. It aims to analyse the complex circuitry of the breast cancer proteome. Here, the authors review how breast cancer proteomics has progressed so far, with emphasis on its potential application to clinically relevant scenarios.

Cyclophilin-D promotes the mitochondrial permeability transition but has opposite effects on apoptosis and necrosis

Cyclophilin-D is a peptidylprolyl cis-trans isomerase of the mitochondrial matrix. It is involved in mitochondrial permeability transition, in which the adenine nucleotide translocase of the inner membrane is transformed from an antiporter to a non-selective pore. The permeability transition has been widely considered as a mechanism in both apoptosis and necrosis. The present study examines the effects of cyclophilin-D on the permeability transition and lethal cell injury, using a neuronal (B50) cell line stably overexpressing cyclophilin-D in mitochondria. Cyclophilin-D overexpression rendered isolated mitochondria far more susceptible to the permeability transition induced by Ca2+ and oxidative stress. Similarly, cyclophilin-D overexpression brought forward the onset of the permeability transition in intact cells subjected to oxidative stress. In addition, in the absence of stress, the mitochondria of cells overexpressing cyclophilin-D maintained a lower inner-membrane potential than those of normal cells. All these effects of cyclophilin-D overexpression were abolished by cyclosporin A. It is concluded that cyclophilin-D promotes the permeability transition in B50 cells. However, cyclophilin-D overexpression had opposite effects on apoptosis and necrosis; whereas NO-induced necrosis was promoted, NO- and staurosporine-induced apoptosis were inhibited. These findings indicate that the permeability transition leads to cell necrosis, but argue against its involvement in apoptosis.