Dendritic cells (DCs) initiate and control immune responses. Plasmacytoid DCs (pDCs) represent a unique DC subset able to promptly release large amounts of type I interferon (IFN-αβ) upon viral ...encounter. Here we report that depletion of pDCs from human blood mononuclear cells abrogates the secretion of specific and polyclonal IgGs in response to influenza virus. Furthermore, purified pDCs triggered with virus induce CD40-activated B cells to differentiate into plasma cells. Two pDC cytokines act sequentially, with IFN-αβ generating non-Ig-secreting plasma blasts and IL-6 inducing their differentiation into Ig-secreting plasma cells. These plasma cells display the high levels of CD38 found on tissue plasma cells. Thus, pDCs are critical for the generation of plasma cells and antibody responses.
The heat‐shock protein 27 (HSP27) is up‐regulated in tumor cells and released in their microenvironment. Here, we show that extracellular HSP27 has a proangiogenic effect evidenced on chick ...chorioallantoic membrane. To explore this effect, we test the recombinant human protein (rhHSP27) at physiopathological doses (0.1–10 μg/ml) onto human microvascular endothelial cells (HMECs) grown as monolayers or spheroids. When added onto HMECs, rhHSP27 dose‐dependently accelerates cell migration (with a peak at 5 (μg/ml) and favors spheroid sprouting within 12‐24 h. rhHSP27 increases VEGF gene transcription and promotes secretion of VEGF‐activating VEGF receptor type 2. Increased VEGF transcription is related to NF‐κB activation in 30 min. All of these effects are initiated by rhHSP27 interaction with Toll‐like receptor 3 (TLR3). Such an interaction can be detected by immunoprecipitation but does not seem to be direct, as we failed to detect an interaction between rhHSP27 and monomeric TLR3 by SPR analysis. rhHSP27 is rapidly internalized with a pool of TLR3 to the endosomal compartment (within 15–30 min), which is required for NF‐κB activation in a cytosolic Ca2+ ‐dependent manner. The HSP27/TLR3 interaction induces NF‐κB activation, leading to VEGF‐mediated cell migration and angiogenesis. Such a pathway provides alternative targets for antiangiogenic cancer therapy.—Thuringer, D., Jego, G., Wettstein, G., Terrier, O., Cronier, L., Yousfi, N., Hébrard, S., Bouchot, A., Hazoumé, A., Joly, A‐L., Gleave, M., Rosa‐Calatrava, M., Solary, E., and Garrido, C., Extracellular HSP27 mediates angiogenesis through Toll‐like receptor 3. FASEB J. 27, 4169–4183 (2013). www.fasebj.org
Activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL) is an aggressive lymphoproliferative disorder involving chronic NF-κB activation. Several mutations in the BCR and MyD88 signaling pathway ...components, such as MyD88 L265P, are implicated in this aberrant activation. Among heat shock proteins, HSP110 has recently been identified as a prosurvival and/or proliferation factor in many cancers, but its role in ABC-DLBCL survival mechanisms remained to be established. We observed that short hairpin RNA–mediated HSP110 silencing decreased the survival of several ABC-DLBCL cell lines and decreased immunoglobulin M-MyD88 co-localization and subsequent NF-κB signaling. Conversely, overexpression of HSP110 in ABC-DLBCL or non-DLBCL cell lines increased NF-κB signaling, indicating a tight interplay between HSP110 and the NF-κB pathway. By using immunoprecipitation and proximity ligation assays, we identified an interaction between HSP110 and both wild-type MyD88 and MyD88 L265P. HSP110 stabilized both MyD88 forms with a stronger effect on MyD88 L265P, thus facilitating chronic NF-κB activation. Finally, HSP110 expression was higher in lymph node biopsies from patients with ABC-DLBCL than in normal reactive lymph nodes, and a strong correlation was found between the level of HSP110 and MyD88. In conclusion, we identified HSP110 as a regulator of NF-κB signaling through MyD88 stabilization in ABC-DLBCL. This finding reveals HSP110 as a new potential therapeutic target in ABC-DLBCL.
•HSP110 sustains chronic NF-κB signaling in ABC-DLBCL through MyD88 stability.•HSP110 is highly expressed in cells of patients with ABC-DLBCL and correlates with MyD88 expression.
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In this study, we have investigated the mRNA expression of the cancer germ‐line genes MAGE, BAGE, GAGE, RAGE and the tumor‐overexpressed gene PRAME by human myeloma cell lines and malignant plasma ...cells from patients with multiple myeloma (MM). By reverse transcription‐PCR, we show that all myeloma cell lines (n = 16) express at least one of these genes, except RAGE‐1 that was never expressed. We show that malignant plasma cells from the majority of MM patients (n = 21) expressed MAGE‐1, MAGE‐3 and PRAME. On the contrary, polyclonal reactive plasma cells did not express any of these genes. By flow cytometry, we show that mage‐1 protein is expressed within myeloma cells and cell lines and that anti‐mage‐1.HLA‐A1 cytotoxic T lymphocytes efficiently killed MAGE‐1+HLA‐A1+ MDN myeloma cells. Taken together, our data show that mage‐1 and mage‐3 could constitute specific targets for tumor immunotherapy of MM patients.
Pro-survival stress-inducible chaperone HSP110 is the only HSP for which a mutation has been found in a cancer. Multicenter clinical studies demonstrated a direct association between HSP110 ...inactivating mutation presence and excellent prognosis in colorectal cancer patients. Here, we have combined crystallographic studies on human HSP110 and in silico modeling to identify HSP110 inhibitors that could be used in colorectal cancer therapy. Two molecules (foldamers 33 and 52), binding to the same cleft of HSP110 nucleotide-binding domain, were selected from a chemical library (by co-immunoprecipitation, AlphaScreening, Interference-Biolayer, Duo-link). These molecules block HSP110 chaperone anti-aggregation activity and HSP110 association to its client protein STAT3, thereby inhibiting STAT3 phosphorylation and colorectal cancer cell growth. These effects were strongly decreased in HSP110 knockdown cells. Foldamer's 33 ability to inhibit tumor growth was confirmed in two colorectal cancer animal models. Although tumor cell death (apoptosis) was noted after treatment of the animals with foldamer 33, no apparent toxicity was observed, notably in epithelial cells from intestinal crypts. Taken together, we identified the first HSP110 inhibitor, a possible drug-candidate for colorectal cancer patients whose unfavorable outcome is associated to HSP110.
Multiple myeloma (MM) patients are strongly vulnerable to infections, which remain a major cause of death. During infection, human immune cells sense the presence of invading pathogens through the ...Toll-like receptor family (TLR), which recognizes pathogen-associated molecular patterns (PAMP). We hypothesized that MM cells also could sense the presence of microorganisms, thus promoting myeloma disease progression. Here, we report that human myeloma cell lines (HMCL) and primary myeloma cells express a broad range of TLR, and are sensitive to the corresponding PAMP. Toll-like receptor 1, 7 and 9 are most frequently expressed by HMCL. The expression pattern of TLR does not correlate with the one of B cells, as TLR2 and 10 are lost while TLR3, 4 and 8 are acquired by some HMCL. Culture with TLR7- and TLR9-ligands saves HMCL from serum-deprivation or dexamethasone-induced apoptosis. Similarly, both ligands increase myeloma cell growth. These effects are mediated by an autocrine secretion of interleukin-6 (IL-6) since the neutralization of IL-6 blocks the growth and survival of HMCL. Thus, TLR expression and function are not restricted to the cells of the immune system and could be of advantage for cancer cells. In MM, recurrent infections could promote tumor growth and favor escape from standard therapies.
HSP110 is induced by different stresses and, through its anti-apoptotic and chaperoning properties, helps the cells to survive these adverse situations. In colon cancers, HSP110 is abnormally ...abundant. We have recently showed that colorectal cancer (CRC) patients with microsatellite instability (MSI) had an improved response to chemotherapy because they harbor an HSP110 inactivating mutation (HSP110DE9). In this work, we have used patients' biopsies and human CRC cells grown in vitro and in vivo (xenografts) to demonstrate that (1) HSP110 is secreted by CRC cells and that the amount of this extracellular HSP110 is strongly decreased by the expression of the mutant HSP110DE9, (2) Supernatants from CRC cells overexpressing HSP110 or purified recombinant human HSP110 (LPS-free) affect macrophage differentiation/polarization by favoring a pro-tumor, anti-inflammatory profile, (3) Conversely, inhibition of HSP110 (expression of siRNA, HSP110DE9 or immunodepletion) induced the formation of macrophages with a cytotoxic, pro-inflammatory profile. (4) Finally, this effect of extracellular HSP110 on macrophages seems to implicate TLR4. These results together with the fact that colorectal tumor biopsies with HSP110 high were infiltrated with macrophages with a pro-tumoral profile while those with HSP110 low were infiltrated with macrophages with a cytotoxic profile, suggest that the effect of extracellular HSP110 function on macrophages may also contribute to the poor outcomes associated with HSP110 expression.
Heat shock proteins (HSPs) are necessary for cancer cell survival. We identified a mutant of HSP110 (HSP110ΔE9) in colorectal cancer showing microsatellite instability (MSI CRC), generated from an ...aberrantly spliced mRNA and lacking the HSP110 substrate-binding domain. This mutant was expressed at variable levels in almost all MSI CRC cell lines and primary tumors tested. HSP110ΔE9 impaired both the normal cellular localization of HSP110 and its interaction with other HSPs, thus abrogating the chaperone activity and antiapoptotic function of HSP110 in a dominant-negative manner. HSP110ΔE9 overexpression caused the sensitization of cells to anticancer agents such as oxaliplatin and 5-fluorouracil, which are routinely prescribed in the adjuvant treatment of people with CRC. The survival and response to chemotherapy of subjects with MSI CRCs was associated with the tumor expression level of HSP110ΔE9. HSP110 may thus constitute a major determinant for both prognosis and treatment response in CRC.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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