Tumour-derived and host-derived nitric oxide differentially regulate breast carcinoma metastasis to the lungs

To study the role of nitric oxide (NO) in lung metastasis of breast carcinoma, we isolated two cell clones (H and J) from the parental EMT-6 murine breast carcinoma cell line, based on their differential NO production. In vitro, EMT-6 J cells, but not EMT-6H cells, constitutively expressed inducible NO synthase (NOS II) and secreted high levels of NO. IL-1β increased NO production in both clones, and TNF-α had a synergistic effect on IL-1β-induced NO production, but NO production by EMT-6 J cells was always higher than by EMT-6H cells. Proliferation, survival and adhesion to lung-derived endothelial cells of both clones were similar and were not affected by NO. In vivo, both clones similarly located in the lungs of syngeneic mice 48 h after injection. However, EMT-6H cells were significantly more tumorigenic than EMT-6 J cells as assessed at later time points. Injection of EMT-6 J cells and simultaneous treatment of mice with aminoguanidine (AG), a NOS II inhibitor, significantly increased tumour formation. Injection of EMT-6H and EMT-6 J cells into NOS II-deficient mice resulted in a significant survival increase as compared with wild-type animals. Simultaneous administration of AG increased the death rate of NOS II-deficient mice injected with EMT-6 J cells. These results demonstrate that: (i) NO does not influence the early stages of tumour metastasis to the lungs and (ii) NOS II expression in tumour cells reduces, while NOS II expression in host cells enhances, tumour nodule development. In conclusion, the cellular origin and the local NO production are critical in the metastatic proces

Tumour-derived and host-derived nitric oxide differentially regulate breast carcinoma metastasis to the lungs

To study the role of nitric oxide (NO) in lung metastasis of breast carcinoma, we isolated two cell clones (H and J) from the parental EMT-6 murine breast carcinoma cell line, based on their differential NO production. In vitro, EMT-6 J cells, but not EMT-6H cells, constitutively expressed inducible NO synthase (NOS II) and secreted high levels of NO. IL-1beta increased NO production in both clones, and TNF-alpha had a synergistic effect on IL-1beta-induced NO production, but NO production by EMT-6 J cells was always higher than by EMT-6H cells. Proliferation, survival and adhesion to lung-derived endothelial cells of both clones were similar and were not affected by NO. In vivo, both clones similarly located in the lungs of syngeneic mice 48 h after injection. However, EMT-6H cells were significantly more tumorigenic than EMT-6 J cells as assessed at later time points. Injection of EMT-6 J cells and simultaneous treatment of mice with aminoguanidine (AG), a NOS II inhibitor, significantly increased tumour formation. Injection of EMT-6H and EMT-6 J cells into NOS II-deficient mice resulted in a significant survival increase as compared with wild-type animals. Simultaneous administration of AG increased the death rate of NOS II-deficient mice injected with EMT-6 J cells. These results demonstrate that: (i) NO does not influence the early stages of tumour metastasis to the lungs and (ii) NOS II expression in tumour cells reduces, while NOS II expression in host cells enhances, tumour nodule development. In conclusion, the cellular origin and the local NO production are critical in the metastatic proces

Dimethylarginine dimethylaminohydrolase I enhances tumour growth and angiogenesis

Angiogenesis is a prerequisite for tumour progression and is highly regulated by growth factors and cytokines a number of which also stimulate the production of nitric oxide. Asymmetric dimethylarginine is an endogenous inhibitor of nitric oxide synthesis. Asymmetric dimethylarginine is metabolised by dimethylarginine dimethylaminohydrolase. To study the effect of dimethylarginine dimethylaminohydrolase on tumour growth and vascular development, the rat C6 glioma cell line was manipulated to overexpress the rat gene for dimethylarginine dimethylaminohydrolase I. Enhanced expression of dimethylarginine dimethylaminohydrolase I increased nitric oxide synthesis (as indicated by a two-fold increase in the production of cGMP), expression and secretion of vascular endothelial cell growth factor, and induced angiogenesis in vitro. Tumours derived from these cells grew more rapidly in vivo than cells with normal dimethylarginine dimethylaminohydrolase I expression. Immunohistochemical and magnetic resonance imaging measurements were consistent with increased tumour vascular development. Furthermore, dimethylarginine dimethylaminohydrolase activity was detected in a series of human tumours. This data demonstrates that dimethylarginine dimethylaminohydrolase plays a pivotal role in tumour growth and the development of the tumour vasculature by regulating the concentration of nitric oxide and altering vascular endothelial cell growth factor production

miR-548d-3p Alters Parasite Growth and Inflammation in Leishmania (Viannia) braziliensis Infection

American Tegumentary Leishmaniasis (ATL) is an endemic disease in Latin America, mainly caused in Brazil by Leishmania (Viannia) braziliensis. Clinical manifestations vary from mild, localized cutaneous leishmaniasis (CL) to aggressive mucosal disease. The host immune response strongly determines the outcome of infection and pattern of disease. However, the pathogenesis of ATL is not well understood, and host microRNAs (miRNAs) may have a role in this context. In the present study, miRNAs were quantified using qPCR arrays in human monocytic THP-1 cells infected in vitro with L. (V.) braziliensis promastigotes and in plasma from patients with ATL, focusing on inflammatory response-specific miRNAs. Patients with active or self-healed cutaneous leishmaniasis patients, with confirmed parasitological or immunological diagnosis, were compared with healthy controls. Computational target prediction of significantly-altered miRNAs from in vitro L. (V.) braziliensis-infected THP-1 cells revealed predicted targets involved in diverse pathways, including chemokine signaling, inflammatory, cellular proliferation, and tissue repair processes. In plasma, we observed distinct miRNA expression in patients with self-healed and active lesions compared with healthy controls. Some miRNAs dysregulated during THP-1 in vitro infection were also found in plasma from self-healed patients, including miR-548d-3p, which was upregulated in infected THP-1 cells and in plasma from self-healed patients. As miR-548d-3p was predicted to target the chemokine pathway and inflammation is a central to the pathogenesis of ATL, we evaluated the effect of transient transfection of a miR-548d-3p inhibitor on L. (V.) braziliensis infected-THP-1 cells. Inhibition of miR-548d-3p reduced parasite growth early after infection and increased production of MCP1/CCL2, RANTES/CCL5, and IP10/CXCL10. In plasma of self-healed patients, MCP1/CCL2, RANTES/CCL5, and IL-8/CXCL8 concentrations were significantly decreased and MIG/CXCL9 and IP-10/CXCL10 increased compared to patients with active disease. These data suggest that by modulating miRNAs, L. (V.) braziliensis may interfere with chemokine production and hence the inflammatory processes underpinning lesion resolution. Our data suggest miR-548d-3p could be further evaluated as a prognostic marker for ATL and/or as a host-directed therapeutic target

Etude de la variabilité de la teneur en sucre chez la carotte

Diplôme : DU