Oxidative stress and inflammation induced by air pollution-derived PM2.5 persist in the lungs of mice after cessation of their sub-chronic exposure.

More than 7 million early deaths/year are attributable to air pollution. Current health concerns are especially focused on air pollution-derived particulate matter (PM). Although oxidative stress-induced airway inflammation is one of the main adverse outcome pathways triggered by air pollution-derived PM, the persistence of both these underlying mechanisms, even after exposure cessation, remained poorly studied. In this study, A/JOlaHsd mice were also exposed acutely (24 h) or sub-chronically (4 weeks), with or without a recovery period (12 weeks), to two urban PM2.5 samples collected during contrasting seasons (i.e., autumn/winter, AW or spring/summer, SS). The distinct intrinsic oxidative potentials (OPs) of AW and SS PM2.5, as evaluated in acellular conditions, were closely related to their respective physicochemical characteristics and their respective ability to really generate ROS over-production in the mouse lungs. Despite the early activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) cell signaling pathway by AW and, in a lesser degree, SS PM2.5, in the murine lungs after acute and sub-chronic exposures, the critical redox homeostasis was not restored, even after the exposure cessation. Accordingly, an inflammatory response was reported through the activation of the nuclear factor-kappa B (NF-κB) cell signaling pathway activation, the secretion of cytokines, and the recruitment of inflammatory cells, in the murine lungs after the acute and sub-chronic exposures to AW and, in a lesser extent, to SS PM2.5, which persisted after the recovery period. Taken together, these original results provided, for the first time, new relevant insights that air pollution-derived PM2.5, with relatively high intrinsic OPs, induced oxidative stress and inflammation, which persisted admittedly at a lower level in the lungs after the exposure cessation, thereby contributing to the occurrence of molecular and cellular adverse events leading to the development and/or exacerbation of future chronic inflammatory lung diseases and even cancers.

Macrophage-Colony-Stimulating Factor Receptor Enhances Prostate Cancer Cell Growth and Aggressiveness In Vitro and In Vivo and Increases Osteopontin Expression.

Prostate cancer is a major public health concern and one of the most prevalent forms of cancer worldwide. The definition of altered signaling pathways implicated in this complex disease is thus essential. In this context, abnormal expression of the receptor of Macrophage Colony-Stimulating Factor-1 (M-CSF or CSF-1) has been described in prostate cancer cells. Yet, outcomes of this expression remain unknown. Using mouse and human prostate cancer cell lines, this study has investigated the functionality of the wild-type CSF-1 receptor in prostate tumor cells and identified molecular mechanisms underlying its ligand-induced activation. Here, we showed that upon CSF-1 binding, the receptor autophosphorylates and activates multiple signaling pathways in prostate tumor cells. Biological experiments demonstrated that the CSF-1R/CSF-1 axis conferred significant advantages in cell growth and cell invasion in vitro. Mouse xenograft experiments showed that CSF-1R expression promoted the aggressiveness of prostate tumor cells. In particular, we demonstrated that the ligand-activated CSF-1R increased the expression of spp1 transcript encoding for osteopontin, a key player in cancer development and metastasis. Therefore, this study highlights that the CSF-1 receptor is fully functional in a prostate cancer cell and may be a potential therapeutic target for the treatment of prostate cancer.

Histone deacetylase 8 interacts with the GTPase SmRho1 in Schistosoma mansoni.

BACKGROUND: Schistosoma mansoni histone deacetylase 8 (SmHDAC8) has elicited considerable interest as a target for drug discovery. Invalidation of its transcripts by RNAi leads to impaired survival of the worms in infected mice and its inhibition causes cell apoptosis and death. To determine why it is a promising therapeutic target the study of the currently unknown cellular signaling pathways involving this enzyme is essential. Protein partners of SmHDAC8 were previously identified by yeast two-hybrid (Y2H) cDNA library screening and by mass spectrometry (MS) analysis. Among these partners we characterized SmRho1, the schistosome orthologue of human RhoA GTPase, which is involved in the regulation of the cytoskeleton. In this work, we validated the interaction between SmHDAC8 and SmRho1 and explored the role of the lysine deacetylase in cytoskeletal regulation. METHODOLOGY/PRINCIPAL FINDINGS: We characterized two isoforms of SmRho1, SmRho1.1 and SmRho1.2. Co- immunoprecipitation (Co-IP)/Mass Spectrometry (MS) analysis identified SmRho1 partner proteins and we used two heterologous expression systems (Y2H assay and Xenopus laevis oocytes) to study interactions between SmHDAC8 and SmRho1 isoforms. To confirm SmHDAC8 and SmRho1 interaction in adult worms and schistosomula, we performed Co-IP experiments and additionally demonstrated SmRho1 acetylation using a Nano LC-MS/MS approach. A major impact of SmHDAC8 in cytoskeleton organization was documented by treating adult worms and schistosomula with a selective SmHDAC8 inhibitor or using RNAi followed by confocal microscopy. CONCLUSIONS/SIGNIFICANCE: Our results suggest that SmHDAC8 is involved in cytoskeleton organization via its interaction with the SmRho1.1 isoform. The SmRho1.2 isoform failed to interact with SmHDAC8, but did specifically interact with SmDia suggesting the existence of two distinct signaling pathways regulating S. mansoni cytoskeleton organization via the two SmRho1 isoforms. A specific interaction between SmHDAC8 and the C-terminal moiety of SmRho1.1 was demonstrated, and we showed that SmRho1 is acetylated on K136. SmHDAC8 inhibition or knockdown using RNAi caused extensive disruption of schistosomula actin cytoskeleton.

2,6-Diaminopurine as a highly potent corrector of UGA nonsense mutations.

Nonsense mutations cause about 10% of genetic disease cases, and no treatments are available. Nonsense mutations can be corrected by molecules with nonsense mutation readthrough activity. An extract of the mushroom Lepista inversa has recently shown high-efficiency correction of UGA and UAA nonsense mutations. One active constituent of this extract is 2,6-diaminopurine (DAP). In Calu-6 cancer cells, in which TP53 gene has a UGA nonsense mutation, DAP treatment increases p53 level. It also decreases the growth of tumors arising from Calu-6 cells injected into immunodeficient nude mice. DAP acts by interfering with the activity of a tRNA-specific 2'-O-methyltransferase (FTSJ1) responsible for cytosine 34 modification in tRNATrp. Low-toxicity and high-efficiency UGA nonsense mutation correction make DAP a good candidate for the development of treatments for genetic diseases caused by nonsense mutations.

Targeting nonsense-mediated mRNA decay in colorectal cancers with microsatellite instability.

Nonsense-mediated mRNA decay (NMD) is responsible for the degradation of mRNAs with a premature termination codon (PTC). The role of this system in cancer is still quite poorly understood. In the present study, we evaluated the functional consequences of NMD activity in a subgroup of colorectal cancers (CRC) characterized by high levels of mRNAs with a PTC due to widespread instability in microsatellite sequences (MSI). In comparison to microsatellite stable (MSS) CRC, MSI CRC expressed increased levels of two critical activators of the NMD system, UPF1/2 and SMG1/6/7. Suppression of NMD activity led to the re-expression of dozens of PTC mRNAs. Amongst these, several encoded mutant proteins with putative deleterious activity against MSI tumorigenesis (e.g., HSP110DE9 chaperone mutant). Inhibition of NMD in vivo using amlexanox reduced MSI tumor growth, but not that of MSS tumors. These results suggest that inhibition of the oncogenic activity of NMD may be an effective strategy for the personalized treatment of MSI CRC.

The long non-coding RNA 91H increases aggressive phenotype of breast cancer cells and up-regulates H19/IGF2 expression through epigenetic modifications.

Numerous genomic imprinting loci are regulated by long non-coding RNA (lncRNA). We have previously identified a new lncRNA at the H19/IGF2 locus transcribed in H19 antisense orientation and named 91H. This RNA is conserved among mammals. In mice, 91H regulates positively IGF2 expression from a novel promoter. However, in human the function of 91H at the H19/IGF2 locus remains largely undeciphered. Here, we observed that 91H, H19 and IGF2 are overexpressed in breast tumors. By using 91H-knockdown breast cancer cells, we demonstrated that 91H exerts oncogenic properties by promoting cell growth, migration and invasion as well as tumor growth in xenografted immunodeficient mouse model. Moreover, 91H-knockdown reduces the expression of H19 and IGF2 in breast cancer cells. By chromatin-immunoprecipitation and methylation studies, we found that 91H expression prevents histone and DNA methylation on the maternal allele at the H19/IGF2 locus. These results indicate that 91H, through epigenetic modifications, is responsible of the maintenance of H19/IGF2 genomic imprinting allowing the allele-specific expression of H19 and IGF2. Taken together, overexpression of 91H in breast cancer and 91H-induced epigenetic modifications on H19/IGF2 locus suggest that 91H may play essential role in breast cancer development. Further studies are needed to investigate their role in terms of diagnosis and therapeutic.

Relationship Between Pneumocystis carinii Burden and the Degree of Host Immunosuppression in an Airborne Transmission Experimental Model.

To quantitatively assess the risk of contamination by Pneumocystis depending on the degree of immunosuppression (ID) of the exposed rat hosts, we developed an animal model, where rats went through different doses of dexamethasone. Then, natural and aerial transmission of Pneumocystis carinii occurred during cohousing of the rats undergoing gradual ID levels (receivers) with nude rats developing pneumocystosis (seeders). Following contact between receiver and seeder rats, the P. carinii burden of receiver rats was determined by toluidine blue ortho staining and by qPCR targeting the dhfr monocopy gene of this fungus. In this rat model, the level of circulating CD4(+) and CD8(+) T lymphocytes remained significantly stable and different for each dose of dexamethasone tested, thus reaching the goal of a new stable and gradual ID rat model. In addition, an inverse relationship between the P. carinii burden and the level of circulating CD4(+) or CD8(+) T lymphocytes was evidenced. This rat model may be used to study other opportunistic pathogens or even co-infections in a context of gradual ID.

H19 non coding RNA-derived miR-675 enhances tumorigenesis and metastasis of breast cancer cells by downregulating c-Cbl and Cbl-b.

H19 is a long non-coding RNA precursor of miR-675 microRNA. H19 is increasingly described to play key roles in the progression and metastasis of cancers from different tissue origins. We have previously shown that the H19 gene is activated by growth factors and increases breast cancer cell invasion. In this study, we established H19/miR-675 ectopic expression models of MDA-MB-231 breast cancer cells to further investigate the underlying mechanisms of H19 oncogenic action. We showed that overexpression of H19/miR-675 enhanced the aggressive phenotype of breast cancer cells including increased cell proliferation and migration in vitro, and increased tumor growth and metastasis in vivo. Moreover, we identified ubiquitin ligase E3 family (c-Cbl and Cbl-b) as direct targets of miR-675 in breast cancer cells. Using a luciferase assay, we demonstrated that H19, through its microRNA, decreased both c-Cbl and Cbl-b expression in all breast cancer cell lines tested. Thus, by directly binding c-Cbl and Cbl-b mRNA, miR-675 increased the stability and the activation of EGFR and c-Met, leading to sustained activation of Akt and Erk as well as enhanced cell proliferation and migration. Our data describe a novel mechanism of protumoral action of H19 in breast cancer.

NGF-induced TrkA/CD44 association is involved in tumor aggressiveness and resistance to lestaurtinib.

There is accumulating evidence that TrkA and its ligand Nerve Growth Factor (NGF) are involved in cancer development. Staurosporine derivatives such as K252a and lestaurtinib have been developed to block TrkA kinase signaling, but no clinical trial has fully demonstrated their therapeutic efficacy. Therapeutic failures are likely due to the existence of intrinsic signaling pathways in cancer cells that impede or bypass the effects of TrkA tyrosine kinase inhibitors. To verify this hypothesis, we combined different approaches including mass spectrometry proteomics, co-immunoprecipitation and proximity ligation assays. We found that NGF treatment induced CD44 binding to TrkA at the plasma membrane and subsequent activation of the p115RhoGEF/RhoA/ROCK1 pathway to stimulate breast cancer cell invasion. The NGF-induced CD44 signaling was independent of TrkA kinase activity. Moreover, both TrkA tyrosine kinase inhibition with lestaurtinib and CD44 silencing with siRNA inhibited cell growth in vitro as well as tumor development in mouse xenograft model; combined treatment significantly enhanced the antineoplastic effects of either treatment alone. Altogether, our results demonstrate that NGF-induced tyrosine kinase independent TrkA signaling through CD44 was sufficient to maintain tumor aggressiveness. Our findings provide an alternative mechanism of cancer resistance to lestaurtinib and indicate that dual inhibition of CD44 and TrkA tyrosine kinase activity may represent a novel therapeutic strategy.

Cryptosporidium parvum-induced ileo-caecal adenocarcinoma and Wnt signaling in a mouse model.

Cryptosporidium species are apicomplexan protozoans that are found worldwide. These parasites constitute a large risk to human and animal health. They cause self-limited diarrhea in immunocompetent hosts and a life-threatening disease in immunocompromised hosts. Interestingly, Cryptosporidium parvum has been related to digestive carcinogenesis in humans. Consistent with a potential tumorigenic role of this parasite, in an original reproducible animal model of chronic cryptosporidiosis based on dexamethasone-treated or untreated adult SCID mice, we formerly reported that C. parvum (strains of animal and human origin) is able to induce digestive adenocarcinoma even in infections induced with very low inoculum. The aim of this study was to further characterize this animal model and to explore metabolic pathways potentially involved in the development of C. parvum-induced ileo-caecal oncogenesis. We searched for alterations in genes or proteins commonly involved in cell cycle, differentiation or cell migration, such as ß-catenin, Apc, E-cadherin, Kras and p53. After infection of animals with C. parvum we demonstrated immunohistochemical abnormal localization of Wnt signaling pathway components and p53. Mutations in the selected loci of studied genes were not found after high-throughput sequencing. Furthermore, alterations in the ultrastructure of adherens junctions of the ileo-caecal neoplastic epithelia of C. parvum-infected mice were recorded using transmission electron microscopy. In conclusion, we found for the first time that the Wnt signaling pathway, and particularly the cytoskeleton network, seems to be pivotal for the development of the C. parvum-induced neoplastic process and cell migration of transformed cells. Furthermore, this model is a valuable tool in understanding the host-pathogen interactions associated with the intricate infection process of this parasite, which is able to modulate host cytoskeleton activities and several host-cell biological processes and remains a significant cause of infection worldwide.

Chronic ingestion of cadmium and lead alters the bioavailability of essential and heavy metals, gene expression pathways and genotoxicity in mouse intestine.

Chronic ingestion of environmental heavy metals such as lead (Pb) and cadmium (Cd) causes various well-documented pathologies in specific target organs following their intestinal absorption and subsequent accumulation. However, little is known about the direct impact of the non-absorbed heavy metals on the small intestine and the colon homeostasis. The aim of our study was to compare the specific bioaccumulation and retention of Cd and Pb and their effect on the essential metal balance in primary organs, with those occurring specifically in the gastrointestinal tract of mice. Various doses of Cd (5, 20 and 100 mg l(-1)) and Pb (100 and 500 mg l(-1)) chloride salts were provided in drinking water for subchronic to chronic exposures (4, 8 and 12 weeks). In contrast to a clear dose- and time-dependent accumulation in target organs, results showed that intestines are poor accumulators for Cd and Pb. Notwithstanding, changes in gene expression of representative intestinal markers revealed that the transport-, oxidative- and inflammatory status of the gut epithelium of the duodenum, ileum and colon were specifically affected by both heavy metal species. Additionally, in vivo comet assay used to evaluate the impact of heavy metals on DNA damage showed clear genotoxic activities of Cd, on both the upper and distal parts of the gastrointestinal tract. Altogether, these results outline the resilience of the gut which balances the various effects of chronic Cd and Pb in the intestinal mucosa. Collectively, it provides useful information for the risk assessment of heavy metals in gut homeostasis and further disease's susceptibility.

Cryptosporidium parvum infection in SCID mice infected with only one oocyst: qPCR assessment of parasite replication in tissues and development of digestive cancer.

Dexamethasone (Dex) treated Severe Combined Immunodeficiency (SCID) mice were previously described as developing digestive adenocarcinoma after massive infection with Cryptosporidium parvum as soon as 45 days post-infection (P.I.). We aimed to determine the minimum number of oocysts capable of inducing infection and thereby gastrointestinal tumors in this model. Mice were challenged with calibrated oocyst suspensions containing intended doses of: 1, 10, 100 or 10(5) oocysts of C. parvum Iowa strain. All administered doses were infective for animals but increasing the oocyst challenge lead to an increase in mice infectivity (P = 0.01). Oocyst shedding was detected at 7 days P.I. after inoculation with more than 10 oocysts, and after 15 days in mice challenged with one oocyst. In groups challenged with lower inocula, parasite growth phase was significantly higher (P = 0.005) compared to mice inoculated with higher doses. After 45 days P.I. all groups of mice had a mean of oocyst shedding superior to 10,000 oocyst/g of feces. The most impressive observation of this study was the demonstration that C. parvum-induced digestive adenocarcinoma could be caused by infection with low doses of Cryptosporidium, even with only one oocyst: in mice inoculated with low doses, neoplastic lesions were detected as early as 45 days P.I. both in the stomach and ileo-caecal region, and these lesions could evolve in an invasive adenocarcinoma. These findings show a great amplification effect of parasites in mouse tissues after challenge with low doses as confirmed by quantitative PCR. The ability of C. parvum to infect mice with one oocyst and to develop digestive adenocarcinoma suggests that other mammalian species including humans could be also susceptible to this process, especially when they are severely immunocompromised.

Fulminant cryptosporidiosis after near-drowning: a human Cryptosporidium parvum strain implicated in invasive gastrointestinal adenocarcinoma and cholangiocarcinoma in an experimental model.

In the present work, we report the characterization of a Cryptosporidium parvum strain isolated from a patient who nearly drowned in the Deule River (Lille, France) after being discharged from the hospital where he had undergone allogeneic stem cell transplantation. After being rescued and readmitted to the hospital, he developed fulminant cryptosporidiosis. The strain isolated from the patient's stools was identified as C. parvum II2A15G2R1 (subtype linked to zoonotic exposure) and inoculated into SCID mice. In this host, this virulent C. parvum isolate induced not only severe infection but also invasive gastrointestinal and biliary adenocarcinoma. The observation of adenocarcinomas that progressed through all layers of the digestive tract to the subserosa and spread via blood vessels confirmed the invasive nature of the neoplastic process. These results indicate for the first time that a human-derived C. parvum isolate is able to induce digestive cancer. This study is of special interest considering the exposure of a large number of humans and animals to this waterborne protozoan, which is highly tumorigenic when inoculated in a rodent model.

Fulminant cryptosporidiosis associated with digestive adenocarcinoma in SCID mice infected with Cryptosporidium parvum TUM1 strain.

We recently demonstrated that Cryptosporidium parvum IOWA strain induces in situ ileo-caecal adenocarcinoma in an animal model. Herein, the ability of another C. parvum strain to induce digestive neoplasia in dexamethasone-treated SCID mice was explored. SCID mice infected with C. parvum TUM1 strain developed a fulminant cryptosporidiosis associated with intramucosal adenocarcinoma, which is considered an early histological sign of invasive cancer. Both evidence of a role of C. parvum in adenocarcinoma induction and the extended prevalence of cryptosporidiosis worldwide, suggest that the risk of C. parvum-induced gastro-intestinal cancer in humans should be assessed.

Development of Cryptosporidium parvum-induced gastrointestinal neoplasia in severe combined immunodeficiency (SCID) mice: severity of lesions is correlated with infection intensity.

We reported previously that Cryptosporidium parvum was able to induce intestinal tumors in severe combined immunodeficiency (SCID) mice treated with corticoids. To further characterize this Cryptosporidium-induced cell transformation, SCID mice treated with dexamethasone were challenged with C. parvum oocysts, and euthanatized sequentially after infection for histologic examination. Ki-67 was used as a marker of cellular proliferation. Our previous results were confirmed, and it was also found that mice receiving higher inocula (10(6)-10(7)) experienced more severe neoplastic development. Additionally, neoplastic changes were observed not only in the caecum but also in the stomach and duodenum of some animals. Interestingly, SCID mice (6/6) inoculated with 10(5)-10(7) oocysts showed high grade intraepithelial neoplasia or adenomas with high grade dysplasia in the caecum after Day 46 post-infection (PI). Immunohistochemistry for Ki-67 staining indicated the neoplastic process associated to cryptosporidiosis, and evidenced the first immunohistochemical alterations at early stages of the process, even at 3 weeks PI.

Cryptosporidium parvum, a potential cause of colic adenocarcinoma.

BACKGROUND: Cryptosporidiosis represents a major public health problem. This infection has been reported worldwide as a frequent cause of diarrhoea. Particularly, it remains a clinically significant opportunistic infection among immunocompromised patients, causing potentially life-threatening diarrhoea in HIV-infected persons. However, the understanding about different aspects of this infection such as invasion, transmission and pathogenesis is problematic. Additionally, it has been difficult to find suitable animal models for propagation of this parasite. Efforts are needed to develop reproducible animal models allowing both the routine passage of different species and approaching unclear aspects of Cryptosporidium infection, especially in the pathophysiology field. RESULTS: We developed a model using adult severe combined immunodeficiency (SCID) mice inoculated with Cryptosporidium parvum or Cryptosporidium muris while treated or not with Dexamethasone (Dex) in order to investigate divergences in prepatent period, oocyst shedding or clinical and histopathological manifestations. C. muris-infected mice showed high levels of oocysts excretion, whatever the chemical immunosuppression status. Pre-patent periods were 11 days and 9.7 days in average in Dex treated and untreated mice, respectively. Parasite infection was restricted to the stomach, and had a clear preferential colonization for fundic area in both groups. Among C. parvum-infected mice, Dex-treated SCID mice became chronic shedders with a prepatent period of 6.2 days in average. C. parvum-inoculated mice treated with Dex developed glandular cystic polyps with areas of intraepithelial neoplasia, and also with the presence of intramucosal adenocarcinoma. CONCLUSION: For the first time C. parvum is associated with the formation of polyps and adenocarcinoma lesions in the gut of Dex-treated SCID mice. Additionally, we have developed a model to compare chronic muris and parvum cryptosporidiosis using SCID mice treated with corticoids. This reproducible model has facilitated the evaluation of clinical signs, oocyst shedding, location of the infection, pathogenicity, and histopathological changes in the gastrointestinal tract, indicating divergent effects of Dex according to Cryptosporidium species causing infection.