Identification of CSNK1D and KLK6 as two common upregulated genes present in BRCA1 mutated triple-negative breast cancer and ovarian epithelial carcinoma.

Deficiency in the breast cancer type 1 (BRCA1) gene expression predisposes to triple-negative breast cancer (TNBC) and ovarian cancer (OC). We previously identified by Comparative Genomic Hybridization (CGH) array a gain in the 17q25.3 genomic region in 90% of the BRCA1 mutated TNBC tissues, where 17 genes were up-regulated. A second region (Chr19_45681759_54221324) was identified as the second most frequent gain in the BRCA1-mutated population and has not yet been described in the context of BRCA1 mutation. We thus aimed to validate the expression of the Casein kinase 1 delta (CSNK1D) gene of Chr17 in TNBC and OC cell lines and to investigate the expression of genes of Chr19 in TNBC cell lines and tissues as well as in OC cell lines. Expression level of the genes of the 17q25.3, 19q13.32,13.33 and 13.41 chromosomal regions was analyzed using RT-PCR in BRCA1 deficient TNBC and OC cell lines, as well as in 10 BRCA1-mutated TNBC tissues versus 10 wild type carriers. Our results revealed a significant upregulation of CSNK1D gene expression in BRCA1 deficient TNBC and OC cell lines when compared to control ones, and a significant aberration in the expression of the other six genes of Chr19 was observed. Interestingly, upregulation of kallikrein-related peptidase 6 (KLK6) was detected among the BRCA1 deficient TNBC (cell lines and tissues) and OC cell lines. In conclusion, our results suggested that CSNK1D and KLK6 expression levels could be very promising in the search for biomarkers for BRCA1 deficient TNBC and OC.

Detection of SARS-CoV-2 B.1.1.529 (Omicron) variant by SYBR Green-based RT-qPCR.

The coronavirus disease 2019 (COVID-19) pandemic is unceasingly spreading across the globe, and recently a highly transmissible Omicron SARS-CoV-2 variant (B.1.1.529) has been discovered in South Africa and Botswana. Rapid identification of this variant is essential for pandemic assessment and containment. However, variant identification is mainly being performed using expensive and time-consuming genomic sequencing. In this study, we propose an alternative RT-qPCR approach for the detection of the Omicron BA.1 variant using a low-cost and rapid SYBR Green method. We have designed specific primers to confirm the deletion mutations in the spike (S Δ143-145) and the nucleocapsid (N Δ31-33) which are characteristics of this variant. For the evaluation, we used 120 clinical samples from patients with PCR-confirmed SARS-CoV-2 infections, and displaying an S-gene target failure (SGTF) when using TaqPath COVID-19 kit (Thermo Fisher Scientific, Waltham, USA) that included the ORF1ab, S, and N gene targets. Our results showed that all the 120 samples harbored S Δ143-145 and N Δ31-33, which was further confirmed by whole-genome sequencing of 10 samples, thereby validating our SYBR Green-based protocol. This protocol can be easily implemented to rapidly confirm the diagnosis of the Omicron BA.1 variant in COVID-19 patients and prevent its spread among populations, especially in countries with high prevalence of SGTF profile.

Pre-operative and early postoperative health-related quality of life of breast cancer woman: a Lebanese prospective study.

Breast cancer (BC) is a major health concern in Lebanon, with an increasing incidence rate due to advancements in treatment modalities. Evaluating the impact of the BC and its treatment on a woman's Health-Related Quality of Life (HRQoL), and comparing these patterns before and after breast conserving surgery is important to identify areas where interventions may be needed to improve the overall well-being of women with BC. This study aimed to evaluate the HRQoL pre and post-operative breast conserving surgery and just prior to initiation of adjuvant therapy in newly diagnosed patients with BC in Lebanon, specifically focusing on changes in body image. A prospective cohort study was conducted on 120 patients in two health care facilities in Lebanon, collecting sociodemographic and clinical data, and using the EORTC QLQ-C30 and QLQ-BR23 questionnaires to evaluate HRQoL. The outcomes were measured at baseline and then one-day post-operative breast surgery. Results revealed a statistically and clinically significant decrease in body image (mean difference of 8.1 points (95% 4.3;11.1)), physical functioning (mean difference of 6.1 points (95% 3.3;8.5)), and emotional functioning (mean difference of -8.4 points (95%-12.4; -4.9) after surgery. Positive change of physical functioning score was observed among married women. Positive change of emotional functioning score was observed among patients with poor body image score and high future perspective score. Our findings provide valuable insights for clinicians and researchers on the impact of breast conserving surgery on HRQoL in Lebanese women.

Repurposing the Antibacterial Agents Peptide 19-4LF and Peptide 19-2.5 for Treatment of Cutaneous Leishmaniasis.

The lack of safe and cost-effective treatments against leishmaniasis highlights the urgent need to develop improved leishmanicidal agents. Antimicrobial peptides (AMPs) are an emerging category of therapeutics exerting a wide range of biological activities such as anti-bacterial, anti-fungal, anti-parasitic and anti-tumoral. In the present study, the approach of repurposing AMPs as antileishmanial drugs was applied. The leishmanicidal activity of two synthetic anti-lipopolysaccharide peptides (SALPs), so-called 19-2.5 and 19-4LF was characterized in Leishmania major. In vitro, both peptides were highly active against intracellular Leishmania major in mouse macrophages without exerting toxicity in host cells. Then, q-PCR-based gene profiling, revealed that this activity was related to the downregulation of several genes involved in drug resistance (yip1), virulence (gp63) and parasite proliferation (Cyclin 1 and Cyclin 6). Importantly, the treatment of BALB/c mice with any of the two AMPs caused a significant reduction in L. major infective burden. This effect was associated with an increase in Th1 cytokine levels (IL-12p35, TNF-α, and iNOS) in the skin lesion and spleen of the L. major infected mice while the Th2-associated genes were downregulated (IL-4 and IL-6). Lastly, we investigated the effect of both peptides in the gene expression profile of the P2X7 purinergic receptor, which has been reported as a therapeutic target in several diseases. The results showed significant repression of P2X7R by both peptides in the skin lesion of L. major infected mice to an extent comparable to that of a common anti-leishmanial drug, Paromomycin. Our in vitro and in vivo studies suggest that the synthetic AMPs 19-2.5 and 19-4LF are promising candidates for leishmaniasis treatment and present P2X7R as a potential therapeutic target in cutaneous leishmaniasis (CL).

SARS-CoV-2 antibody seroprevalence in Lebanon: findings from the first nationwide serosurvey.

BACKGROUND: Lebanon, a small country in the Middle East, remains severely affected by the COVID-19 pandemic. Seroprevalence surveys of anti-SARS-CoV-2 antibodies provide accurate estimates of SARS-CoV-2 infection and hence evaluate the extent of the pandemic. The present study aimed to evaluate the prevalence of SARS-CoV-2 antibodies in Lebanon and to compare the estimated cumulative number of COVID-19 cases with the officially registered number of laboratory-confirmed cases up to January 15, 2021. METHODS: A nationwide population-based serosurvey study was conducted in Lebanon between December 7, 2020, and January 15, 2021, before the initiation of the national vaccination program. The nCOVID-19 IgG & IgM point-of-care (POCT) rapid test was used to detect the presence of anti-SARS-COV-2 immunoglobulin G (IgG) in the blood. Seroprevalence was estimated after weighting for sex, age, and area of residence and adjusting for the test performance. RESULTS: Of the 2058 participants, 329 were positive for IgG SARS-COV-2, resulting in a crude seroprevalence of 16.0% (95% CI 14.4-17.6). The weighed seroprevalence was 15.9% (95% CI of 14.4 and 17.4). After adjusting for test performance, the population weight-adjusted seroprevalence was 18.5% (95% CI 16.8-20.2). This estimate implies that 895,770 individuals of the general population were previously infected by COVID-19 up to January 15, 2021 in Lebanon. The overall estimated number of subjects with previous SARS-CoV-2 infection was three times higher than the officially reported cumulative number of confirmed cases. Seroprevalence was similar across age groups and sexes (p-value > 0.05). However, significant differences were revealed across governorates. CONCLUSIONS: Our results suggest that the Lebanese population is still susceptible to SARS-CoV-2 infection and far from achieving herd immunity. These findings represent an important contribution to the surveillance of the COVID-19 pandemic in Lebanon and to the understanding of how this virus spreads. Continued surveillance for COVID-19 cases and maintaining effective preventive measures are recommended to control the epidemic spread in conjunction with a national vaccination campaign to achieve the desired level of herd immunity against COVID-19.

A rapid and low-cost protocol for the detection of B.1.1.7 lineage of SARS-CoV-2 by using SYBR Green-based RT-qPCR.

BACKGROUND: The new SARS-CoV-2 variant VOC (202012/01), identified recently in the United Kingdom (UK), exhibits a higher transmissibility rate compared to other variants, and a reproductive number 0.4 higher. In the UK, scientists were able to identify the increase of this new variant through the rise of false negative results for the spike (S) target using a three-target RT-PCR assay (TaqPath kit). METHODS: To control and study the current coronavirus pandemic, it is important to develop a rapid and low-cost molecular test to identify the aforementioned variant. In this work, we designed primer sets specific to the VOC (202012/01) to be used by SYBR Green-based RT-PCR. These primers were specifically designed to confirm the deletion mutations Δ69/Δ70 in the spike and the Δ106/Δ107/Δ108 in the NSP6 gene. We studied 20 samples from positive patients, detected by using the Applied Biosystems TaqPath RT-PCR COVID-19 kit (Thermo Fisher Scientific, Waltham, USA) that included the ORF1ab, S, and N gene targets. 16 samples displayed an S-negative profile (negative for S target and positive for N and ORF1ab targets) and four samples with S, N and ORF1ab positive profile. RESULTS: Our results emphasized that all S-negative samples harbored the mutations Δ69/Δ70 and Δ106/Δ107/Δ108. This protocol could be used as a second test to confirm the diagnosis in patients who were already positive to COVID-19 but showed false negative results for S-gene. CONCLUSIONS: This technique may allow to identify patients carrying the VOC (202012/01) or a closely related variant, in case of shortage in sequencing.

Probing the Increased Virulence of Severe Acute Respiratory Syndrome Coronavirus 2 B.1.617 (Indian Variant) From Predicted Spike Protein Structure.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to an outbreak of a pandemic worldwide. The spike (S) protein of SARS-CoV-2, which plays a key role in the receptor recognition and cell membrane fusion process, is composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain that recognizes and binds to the host receptor angiotensin-converting enzyme 2 (ACE2), while the S2 subunit mediates viral cell membrane fusion with the cell membrane and subsequent entry into cells. Mutations in the spike protein (S) are of particular interest due to their potential for reduced susceptibility to neutralizing antibodies or increasing the viral transmissibility and infectivity. Recently, many mutations in the spike protein released new variants, including the Delta and Kappa ones (known as the Indian variants). The variants Delta and Kappa are now of most recent concern because of their well-increased infectivity, both a spin-off of the B.1.617 lineage, which was first identified in India in October 2020. This study employed homology modeling to probe the potential structural effects of the mutations. It was found that the mutations, Leu452Arg, Thr478Lys, and Glu484Gln in the spike protein increase the affinity for the hACE2 receptor, which explains the greater infectivity of the SARS-Cov-2 B.1.617 (Indian Variant).

Malignant carcinoma and skin melanoma neoplasms concomitantly in the thyroid.

Malignant melanomas metastatic to the thyroid gland are uncommon. Based on microscopy and DNA methylation profile, we report a rare coexistence of neoplasms in the thyroid, presumably in our case, with relapse-free condition on adjuvant therapy.

In vivo evaluation of the virucidal efficacy of chlorhexidine and povidone-iodine mouthwashes against salivary SARS-CoV-2. A randomized-controlled clinical trial.

OBJECTIVES: The oral cavity is potentially high-risk transmitter of COVID-19. Antimicrobial mouthrinses are used in many clinical preprocedural situations for decreasing the risk of cross-contamination in the dental setting. It is important to investigate the efficacy of mouthwash solutions against salivary SARS-CoV-2 in order to reduce the exposure of the dental team during dental procedures. AIMS: The aim of this in vivo study was to evaluate the efficacy of 2 preprocedural mouthrinses in the reduction of salivary SARS-CoV-2 viral load and to compare the results of the mouthwashes to a control group. MATERIALS AND METHODS: In this randomized-controlled clinical trial, studied group comprised laboratory-confirmed COVID-19 positive patients through nasopharyngeal swabs. Participants were divided into 3 groups. For 30 s, the control group mouthrinsed with distilled water, the Chlorhexidine group mouthrinsed with 0.2% Chlorhexidine and the Povidone-iodine group gargled with 1% Povidone-iodine. Saliva samples were collected before and 5 min after mouthwash. SARS-CoV-2 rRT-PCR was then performed for each sample. Evaluation of the efficacy was based on difference in cycle threshold (Ct) value. The analysis of data was carried out using GraphPad Prism version 5 for Windows. Kristal wullis and Paired t-test were used. A probability value of less than 0.05 was regarded as statistically significant. RESULTS: Sixty-one compliant participants (36 female and 25 male) with a mean age 45.3 ± 16.7 years-old were enrolled. A significant difference was noted between the delta Ct of distilled water wash and each of the 2 solutions Chlorhexidine 0.2% (P = .0024) and 1% Povidone-iodine (P = .012). No significant difference was found between the delta Ct of patients using Chlorhexidine 0.2% and 1% Povidone-iodine solutions (P = .24). A significant mean Ct value difference (P < .0001) between the paired samples in Chlorhexidine group (n = 27) and also in Povidone-iodine group (n = 25) (P < .0001) was found. In contrast, no significant difference (P = .566) existed before and after the experiment in the control group (n = 9). CONCLUSION: Chlorhexidine 0.2% and 1% Povidone-iodine oral solutions are effective preprocedural mouthwashes against salivary SARS-CoV-2 in dental treatments. Their use as a preventive strategy to reduce the spread of COVID-19 during dental practice should be considered.

Activity of Anti-Microbial Peptides (AMPs) against Leishmania and Other Parasites: An Overview.

Anti-microbial peptides (AMPs), small biologically active molecules, produced by different organisms through their innate immune system, have become a considerable subject of interest in the request of novel therapeutics. Most of these peptides are cationic-amphipathic, exhibiting two main mechanisms of action, direct lysis and by modulating the immunity. The most commonly reported activity of AMPs is their anti-bacterial effects, although other effects, such as anti-fungal, anti-viral, and anti-parasitic, as well as anti-tumor mechanisms of action have also been described. Their anti-parasitic effect against leishmaniasis has been studied. Leishmaniasis is a neglected tropical disease. Currently among parasitic diseases, it is the second most threating illness after malaria. Clinical treatments, mainly antimonial derivatives, are related to drug resistance and some undesirable effects. Therefore, the development of new therapeutic agents has become a priority, and AMPs constitute a promising alternative. In this work, we describe the principal families of AMPs (melittin, cecropin, cathelicidin, defensin, magainin, temporin, dermaseptin, eumenitin, and histatin) exhibiting a potential anti-leishmanial activity, as well as their effectiveness against other microorganisms.

Helicobacter pylori outer membrane vesicles induce expression and secretion of oncostatin M in AGS gastric cancer cells.

Helicobacter pylori, a human pathogen that colonizes the stomach of 50% of the world's population, is associated with gastritis, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. Diseases are characterized by severe inflammatory responses in the stomach that are induced by various chemokines and cytokines. Recently, oncostatin M (OSM), an IL-6 family cytokine, was detected in early gastric cancer biopsies. In this study, we showed that Helicobacter pylori induced secretion of OSM and overexpression of its type II receptor OSMRß (OSM/OSMRß) in a human gastric adenocarcinoma cell line (AGS) over 24 h of infection. Furthermore, we showed that the induction of OSM and OSMRß was carried out by heat-sensitive Helicobacter pylori outer membrane vesicle (OMV) protein. Collectively, our results established, for the first time, a direct relation between Helicobacter pylori OMVs and the OSM/OSMRß signaling axis.

Variant analysis of the first Lebanese SARS-CoV-2 isolates.

Recently the first genome sequences for 11 SARS-CoV-2 isolates from Lebanon became available. Here, we report the detection of variants within the genome of these strains. Pairwise alignment analysis using blastx was performed between these sequences and the UniProtKB data for the SARS-CoV-2 coronavirus to identify amino acid variations. Variants analysis was performed using multiple Bioinformatics tools. We noticed for the first time 18 mutations that have never been reported before. Among those, a frame shift (8651A>) in NSP4, a stop codon 6887A > T in NSP3 and two missense mutations in spike S2 were found. In addition, we found 28 variants in ORF1ab alone. A previously reported variant, 23403A > G, in the spike protein S2 was mostly seen. Two other known mutations 25563G > T in ORF3a and 14408C > T in ORF1ab were detected respectively in 6 and 8 out of the 11 isolates. Our results may help to prognose forthcoming infections in this region.

Triple negative breast cancer: microRNA expression profile and novel discriminators according to BRCA1 status.

Triple-negative breast cancer (TNBC) represents 15% of breast carcinomas. More than 80% of women with a breast cancer associated with a breast cancer type 1 (BRCA1) mutation develop a TNBC. microRNAs (miRNAs) play critical roles in diverse biological processes and are aberrantly expressed in several human neoplasms including breast cancer, where they function as actors of tumor onset, behavior, and progression. However, an extensive microRNA profile has not yet been determined for TNBC. Taqman low-density arrays (TLDAs) were used to screen the expression level of 667 miRNAs in TNBC versus normal breast tissues. Our TLDA results revealed 20 differentially expressed miRNAs among which 14 (10 upregulated and four downregulated) were confirmed by an individual quantitative real-time polymerase chain reaction. Interestingly, a novel link between BRCA1 status and miRNA expression level was identified through miR-96 and miR-10b that were very important discriminators between TNBC with mutated BRCA1 and TNBC with wild type BRCA1. This study promises discoveries of new pathological pathways at work in this dreadful disease and clearly warrants validation in large prospective studies with the aim of identifying novel biomarkers for diagnosis and targets for clinical interventions.

The MicroRNA miR-210 Is Expressed by Cancer Cells but Also by the Tumor Microenvironment in Triple-Negative Breast Cancer.

The triple-negative breast cancer (TNBC) subtype occurs in about 15% of breast cancer and is an aggressive subtype of breast cancer with poor outcome. Furthermore, treatment of patients with TNBC is more challenging due to the heterogeneity of the disease and the absence of well-defined molecular targets. Microribonucleic acid (RNA) represents a new class of biomarkers that are frequently dysregulated in cancer. It has been described that the microRNA miR-210 is highly expressed in TNBC, and its overexpression had been linked to poor prognosis. TNBC are often infiltrated by immune cells that play a key role in cancer progression. The techniques traditionally used to analyze miR-210 expression such as next generation sequencing or quantitative real-time polymerase chain reaction (PCR) do not allow the precise identification of the cellular subtype expressing the microRNA. In this study, we have analyzed miR-210 expression by in situ hybridization in TNBC. The miR-210 signal was detected in tumor cells, but also in the tumor microenvironment, in a region positive for the pan-leucocyte marker CD45-LCA. Taken together, our results demonstrate that miR-210 is expressed in tumor cells but also in the tumor microenvironment. Our results also highlight the utility of using complementary approaches to take into account the cellular context of microRNA expression.

Identification by array comparative genomic hybridization of a new amplicon on chromosome 17q highly recurrent in BRCA1 mutated triple negative breast cancer.

INTRODUCTION: Triple Negative Breast Cancers (TNBC) represent about 12% to 20% of all breast cancers (BC) and have a worse outcome compared to other BC subtypes. TNBC often show a deficiency in DNA double-strand break repair mechanisms. This is generally related to the inactivation of a repair enzymatic complex involving BRCA1 caused either by genetic mutations, epigenetic modifications or by post-transcriptional regulations. The identification of new molecular biomarkers that would allow the rapid identification of BC presenting a BRCA1 deficiency could be useful to select patients who could benefit from PARP inhibitors, alkylating agents or platinum-based chemotherapy. METHODS: Genomic DNA from 131 formalin-fixed paraffin-embedded (FFPE) tumors (luminal A and B, HER2+ and triple negative BC) with known BRCA1 mutation status or unscreened for BRCA1 mutation were analysed by array Comparative Genomic Hybridization (array CGH). One highly significant and recurrent gain in the 17q25.3 genomic region was analysed by fluorescent in situ hybridization (FISH). Expression of the genes of the 17q25.3 amplicon was studied using customized Taqman low density arrays and single Taqman assays (Applied Biosystems). RESULTS: We identified by array CGH and confirmed by FISH a gain in the 17q25.3 genomic region in 90% of the BRCA1 mutated tumors. This chromosomal gain was present in only 28.6% of the BRCA1 non-mutated TNBC, 26.7% of the unscreened TNBC, 13.6% of the luminal B, 19.0% of the HER2+ and 0% of the luminal A breast cancers. The 17q25.3 gain was also detected in 50% of the TNBC with BRCA1 promoter methylation. Interestingly, BRCA1 promoter methylation was never detected in BRCA1 mutated BC. Gene expression analyses of the 17q25.3 sub-region showed a significant over-expression of 17 genes in BRCA1 mutated TNBC (n = 15) as compared to the BRCA1 non mutated TNBC (n = 13). CONCLUSIONS: In this study, we have identified by array CGH and confirmed by FISH a recurrent gain in 17q25.3 significantly associated to BRCA1 mutated TNBC. Up-regulated genes in the 17q25.3 amplicon might represent potential therapeutic targets and warrant further investigation.

Unraveling networks of co-regulated genes on the sole basis of genome sequences.

With the growing number of available microbial genome sequences, regulatory signals can now be revealed as conserved motifs in promoters of orthologous genes (phylogenetic footprints). A next challenge is to unravel genome-scale regulatory networks. Using as sole input genome sequences, we predicted cis-regulatory elements for each gene of the yeast Saccharomyces cerevisiae by discovering over-represented motifs in the promoters of their orthologs in 19 Saccharomycetes species. We then linked all genes displaying similar motifs in their promoter regions and inferred a co-regulation network including 56,919 links between 3171 genes. Comparison with annotated regulons highlights the high predictive value of the method: a majority of the top-scoring predictions correspond to already known co-regulations. We also show that this inferred network is as accurate as a co-expression network built from hundreds of transcriptome microarray experiments. Furthermore, we experimentally validated 14 among 16 new functional links between orphan genes and known regulons. This approach can be readily applied to unravel gene regulatory networks from hundreds of microbial genomes for which no other information is available except the sequence. Long-term benefits can easily be perceived when considering the exponential increase of new genome sequences.

Amino acid signaling in yeast: activation of Ssy5 protease is associated with its phosphorylation-induced ubiquitylation.

The yeast Ssy5 protein is a serine-type endoprotease autoprocessed into a catalytic domain and a large inhibitory prodomain. When external amino acids are detected by the plasma membrane Ssy1 sensor, Ssy5 is activated and catalyzes endoproteolytic processing of the Stp1 and Stp2 transcription factors. These Stp proteins then migrate into the nucleus and activate transcription of several amino acid permease genes. Previous studies showed that Ssy5 activation involves the SCFGrr1 ubiquitin ligase complex, but the molecular mechanisms of this activation remain unclear. We here report that the prodomain of Ssy5 is phosphorylated in a casein kinase I-dependent manner in response to amino acid detection. We describe a mutant form of Ssy5 whose prodomain is not phosphorylated and show that it is nonfunctional. Amino acid detection also induces ubiquitylation of the Ssy5 prodomain. This prodomain ubiquitylation requires its prior phosphorylation and the SCFGrr1 complex. When this ubiquitylation is defective, Ssy5 accumulates as a phosphorylated form but remains inactive. A constitutive Ssy5 form in which the prodomain fails to inhibit the catalytic domain does not need to be phosphorylated or ubiquitylated to be active. Finally, we provide evidence that ubiquitylation of the inhibitory prodomain rather than its subsequent degradation is the key step in the Ssy5 activation mechanism. We propose that the Ssy5 protease is activated by phosphorylation-induced ubiquitylation, the effect of which is relief from inhibition by its prodomain.

Up-regulation of cathepsin B expression and enhanced secretion in mitochondrial DNA-depleted osteosarcoma cells.

BACKGROUND INFORMATION: mtDNA (mitochondrial DNA) mutations that impair oxidative phosphorylation can contribute to carcinogenesis through the increased production of reactive oxygen species and through the release of proteins involved in cell motility and invasion. On the other hand, many human cancers are associated with both the up-regulation and the increased secretion of several proteases and heparanase. In the present study, we tried to determine whether the depletion in mtDNA could modulate the expression and/or the secretion of some lysosomal hydrolases in the 143B osteosarcoma cells, as these mtDNA-depleted cells are characterized by a higher degree of invasiveness than the parental cells. RESULTS: In comparison with the parental cells, we measured a higher amount of procathepsin B in the conditioned culture medium of the 143B cells lacking mtDNA (rho(0) 143B cells), as well as a rise in the specific activity of intracellular cathepsin B. In addition, we observed an activation of the transcription factor NF-kappaB (nuclear factor kappaB) in the cells devoid of functional mitochondria. Finally, we demonstrated that the down-regulation of the NF-kappaB p65 subunit by RNA interference led to a reduction in cathepsin B expression in rho(0) 143B cells. CONCLUSIONS: The up-regulation of cathepsin B by NF-kappaB, followed by its secretion into the extracellular environment, might be partly responsible for the previously reported invasiveness of the mtDNA-depleted 143B osteosarcoma cells.

Palmitoylation of the TRAIL receptor DR4 confers an efficient TRAIL-induced cell death signalling.

S-palmitoylation is a lipid modification that regulates membrane-protein association and influences protein trafficking, stability or aggregation, thus playing an important role in protein signalling. We previously demonstrated that the palmitoylation of Fas, one of the DD (death domain)-containing members of the TNFR [TNF (tumour necrosis factor) receptor] superfamily, is essential for the redistribution of this receptor into lipid rafts, an obligatory step for the death signal transmission. Here we investigate the requirement of protein palmitoylation in the activities of other DD-containing death receptors. We show that DR4 is palmitoylated, whereas DR5 and TNFR1 are not. Furthermore, DR4 palmitoylation is required for its raft localization and its ability to oligomerize, two essential features in TRAIL (TNF-related apoptosis-inducing ligand)-induced death signal transmission.