Oncogenic human papillomavirus could directly interact with Natural Killer cells

Poster (2012, June 22)

The angiogenesis suppressor gene AKAP12 is under the epigenetic control of HDAC7 in endothelial cells.

Conference (2012, April 21)

Metallothionein-dependent up-regulation of TGF-B2 participates in the remodelling of the myxomatous mitral valve.

in Cardiovascular Research (2012), 93(3), 480-9

New prospects in the roles of the C-terminal domains of VEGF-A and their cooperation for ligand binding, cellular signaling and vessels formation.

in Angiogenesis (2012), sous presse

VEGF-A is a crucial growth factor for blood vessel homeostasis and pathological angiogenesis. Due to alternative splicing of its pre-mRNA, VEGF-A is produced under several isoforms characterized by the ... [more ▼]

VEGF-A is a crucial growth factor for blood vessel homeostasis and pathological angiogenesis. Due to alternative splicing of its pre-mRNA, VEGF-A is produced under several isoforms characterized by the combination of their C-terminal domains, which determines their respective structure, availability and affinity for co-receptors. As controversies still exist about the specific roles of these exon-encoded domains, we systematically compared the properties of eight natural and artificial variants containing the domains encoded by exons 1-4 and various combinations of the domains encoded by exons 5, 7 and 8a or 8b. All the variants (VEGF(111)a, VEGF(111)b, VEGF(121)a, VEGF(121)b, VEGF(155)a, VEGF(155)b, VEGF(165)a, VEGF(165)b) have a similar affinity for VEGF-R2, as determined by Surface plasmon resonance analyses. They strongly differ however in terms of binding to neuropilin-1 and heparin/heparan sulfate proteoglycans. Data indicate that the 6 amino acids encoded by exon 8a must be present and cooperate with those of exons 5 or 7 for efficient binding, which was confirmed in cell culture models. We further showed that VEGF(165)b has inhibitory effects in vitro, as previously reported, but that the shortest VEGF variant possessing also the 6 amino acids encoded by exon 8b (VEGF(111)b) is remarkably proangiogenic, demonstrating the critical importance of domain interactions for defining the VEGF properties. The number, size and localization of newly formed blood vessels in a model of tumour angiogenesis strongly depend also on the C-terminal domain composition, suggesting that association of several VEGF isoforms may be more efficient for treating ischemic diseases than the use of any single variant. [less ▲]

Human papillomavirus entry into NK cells requires CD16 expression and triggers cytotoxic activity and cytokine secretion.

in European journal of immunology (2011), 41(11), 3240-3252

Human papillomavirus (HPV) infections account for more than 50% of infection-linked cancers in women worldwide. The immune system controls, at least partially, viral infection and around 90% of HPV ... [more ▼]

Human papillomavirus (HPV) infections account for more than 50% of infection-linked cancers in women worldwide. The immune system controls, at least partially, viral infection and around 90% of HPV-infected women clear the virus within two years. However, it remains unclear which immune cells are implicated in this process and no study has evaluated the direct interaction between HPVs and NK cells, a key player in host resistance to viruses and tumors. We demonstrated an NK cell infiltration in HPV-associated pre-neoplastic cervical lesions. Since HPVs cannot grow in vitro, virus-like particles (VLPs) were used as a model for studying the NK cell response against the virus. Interestingly, NK cells displayed higher cytotoxic activity and cytokine production (TNF-alpha and IFN-gamma) in the presence of HPV-VLPs. Using flow cytometry and microscopy we observed that NK cell stimulation was linked to rapid VLP entry into these cells by macropinocytosis. Using CD16(+) and CD16(-) NK cell lines and a CD16-blocking antibody, we demonstrated that CD16 is necessary for HPV-VLP internalization, as well as for degranulation and cytokine production. Thus, we show for the first time that NK cells interact with HPVs and can participate in the immune response against HPV-induced lesions. [less ▲]

RhoGDIalpha-dependent balance between RhoA and RhoC is a key regulator of cancer cell tumorigenesis.

in Molecular Biology of the Cell (2011), 22(17), 3263-75

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA ... [more ▼]

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA-related subclass, RhoA and RhoC contribute to several steps of tumor growth, and the regulation of their expression affects cancer progression. Our aim is to investigate their respective contributions to the acquisition of an invasive phenotype by using models of reduced or forced expression. The silencing of RhoC, but not of RhoA, increased the expression of genes encoding tumor suppressors, such as nonsteroidal anti-inflammatory drug-activated gene 1 (NAG-1), and decreased migration and the anchorage-independent growth in vitro. In vivo, RhoC small interfering RNA (siRhoC) impaired tumor growth. Of interest, the simultaneous knockdown of RhoC and NAG-1 repressed most of the siRhoC-related effects, demonstrating the central role of NAG-1. In addition of being induced by RhoC silencing, NAG-1 was also largely up-regulated in cells overexpressing RhoA. The silencing of RhoGDP dissociation inhibitor alpha (RhoGDIalpha) and the overexpression of a RhoA mutant unable to bind RhoGDIalpha suggested that the effect of RhoC silencing is indirect and results from the up-regulation of the RhoA level through competition for RhoGDIalpha. This study demonstrates the dynamic balance inside the RhoGTPase network and illustrates its biological relevance in cancer progression. [less ▲]

The RhoGDIalpha-dependent balance between RhoA and Rho C is a key regulator of cancer cell tumorigenesis.

Poster (2011)

Evaluation of the potential interest of VEGF chimeric variant (VEGF111b) in inhibition of angiogenesis.

Poster (2011)

The RhoGDI-dependent balance between RhoA and Rho Cis a key regulator of cancer cell tumorigenesis.

Conference (2011)

HPV triggers NK cell cytotoxic activity and cytokine secretion

Conference (2011)

Background The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumor development as demonstrated by a higher tumor prevalence in immunodeficient patients ... [more ▼]

Background The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumor development as demonstrated by a higher tumor prevalence in immunodeficient patients. Around 90% of HPV-infected women will clear the virus within two years. However, it remains unclear which immune cells are implicated in this process and no study has been performed evaluating the direct interaction between HPV and Natural Killer (NK) cells although these cells play a key role in host resistance to virus and tumor. Methods/Results By immunochemistry, we demonstrated an NK cell infiltration in HPV+ squamous pre-neoplasic lesions. Since HPV cannot grow in vitro, virus-like particles (VLP) were used as a model for studying the NK cell response against the virus. Interestingly, NK cells displayed a higher cytotoxic activity (CD107 and chromium release assays) and cytokine production (TNF-α and IFN-γ) in the presence of HPV-VLP. Uptake of HPV-VLP by dendritic cells (DC) has been shown to induce their activation, therefore, we investigated by flow cytometry and microscopy whether the stimulation of NK cell activity is linked to VLP internalization. We observed a faster entry into these cells compared to DC. Furthermore, virus uptake by NK cells is mediated by macropinocytosis, whereas this entry is dependent on clathrin or caveolin endocytosis pathways in DC. Using NK cell lines expressing or not CD16 and blocking antibody, we demonstrated that CD16 is necessary for HPV-VLP internalization, but also for degranulation and cytokine production. Conclusion Thus, we show for the first time that NK cells interact with HPV and could participate in the immune response against HPV-induced tumors. [less ▲]