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Toll-like receptor 3 (TLR3) is a pattern-recognition receptor known to initiate an innate immune response when stimulated by double-stranded RNA (dsRNA). Components of TLR3 signaling, including TIR domain-containing adapter inducing IFN-α (TRIF), have been demonstrated to contribute to dsRNA-induced cell death through caspase-8 and receptor interacting protein (RIP)1 in various human cancer cells. We provide here a detailed analysis of the caspase-8 activating machinery triggered in response to Poly(I:C) dsRNA. Engagement of TLR3 by dsRNA in both type I and type II lung cancer cells induces the formation of an atypical caspase-8-containing complex that is devoid of classical death receptors of the TNFR superfamily, but instead is physically associated to TLR3. The recruitment of caspase-8 to TLR3 requires RIP1, and is negatively modulated by cellular inhibitor of apoptosis protein (cIAP)2-TNF receptor-associated factor (TRAF)2-TNFR-associated death domain (TRADD) ubiquitin ligase complex, which regulates RIP1 ubiquitination. Intriguingly, unlike Fas- or TRAILR-dependent death signaling, caspase-8 recruitment and activation within the TLR3 death-signaling complex appears not to be stringently dependent on Fas-associated with death domain (FADD). Our findings uncover a novel aspect of the molecular mechanisms involved during apoptosis induced by the innate immune receptor TLR3 in cancer cells.

The efficacy of immune response to control human cancer remains controversial. It is particularly debated whether and to what extent the capacity of tumor-infiltrating dendritic cells (DC) to drive immunization can be turned off by transformed cells, leading to tumor-specific tolerance rather than immunization. To address this issue, we have characterized the DC isolated from human non-small cell lung cancer (NSCLC). These biopsy specimens contained CD11c(high) myeloid DC (mDC), but also CD11c(-) plasmacytoid DC (pDC) and a third DC subset expressing intermediate level of CD11c. Compared with peripheral blood, CD11c(high) tumor-infiltrating DC (TIDC) displayed a "semi-mature" phenotype, and TLR4 or TLR8 stimulation drove them to mature partially and to secrete limited amounts of cytokines. In contrast, most tumor-infiltrating pDC were immature but underwent partial maturation after TLR7 activation, whereas TLR9 ligation triggered low secretion of IFN-alpha. CD11c(int) mDC represented approximately 25% of total DC in tumoral and peritumoral tissues and expressed low levels of costimulatory molecules contrasting with high levels of the immunoinhibitory molecule B7-H1. Finally, the poor APC function of total TIDC even after TLR stimulation and the migratory response of both tumor-infiltrating mDC and pDC toward CCL21 and SDF-1 in vitro suggested their ability to compromise the tumor-specific immune response in draining lymph nodes in vivo. Further studies will be required to establish the specific role of the three TIDC subsets in tumor immunity and to draw conclusions for the design of therapeutic strategies.

Purpose: To determine the prevalence and the prognostic value of microtubule component expression in tumors of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC)., Experimental Design: Expression of microtubular components was immunohistochemically examined in 93 tumor samples from untreated patients with stage III and IV NSCLC. All patients received vinorelbine-based chemotherapy. Response to chemotherapy, progression-free survival, and overall survival were correlated with the expression of microtubule proteins., Results: The response rate was 27.3% (21 partial responses among 77 valuable patients). Although expression of microtubule components was not associated with the response rate, high class III beta-tubulin expression was correlated with resistance to vinorelbine, defined as disease progression under treatment. Patients whose tumors expressed high levels of class III beta-tubulin isotype had shorter progression-free survival and overall survival (P = 0.002 and 0.001, respectively). High Delta2 alpha-tubulin expression was associated with a shorter overall survival (P = 0.018). Tubulin II levels were not found to be correlated with patient outcome. A multivariate analysis, taking into account sex, age, histology, stage, weight loss, and class II beta-tubulin, class III beta-tubulin, and Delta2 alpha-tubulin levels, confirmed that class III beta-tubulin expression was independently correlated with progression-free survival (P = 0.04) and overall survival (P = 0.012)., Conclusions: These findings suggest that a high level of expression of class III beta-tubulin in tumor cells is associated with resistance to vinorelbine and a poor prognosis in patients with NSCLC receiving vinorelbine-based chemotherapy.

Cystic fibrosis is characterized by a damaged airway epithelium with inflammation and chronic infection. The aim of this study was to investigate the process of apoptosis in this disease. To evaluate the effects of interferon gamma and the Fas apoptotic pathway on cystic fibrosis airway epithelial cells, we used immortalized cystic fibrosis (CFT-1 and CFT-2) and normal (NT-1) human tracheal epithelial cell lines. Cell death was determined usingannexin-V/propidium iodide labelling and electron microscopy. In vitro expression of Fas and CD40 surface antigens was analysed by immunofluorescence staining and flow cytometry. Normal and cystic fibrosis cells constitutively express these antigens. CD40, but not Fas expression, was upregulated by interferon gamma. Treatment of interferon gamma-stimulated cells with anti-Fas resulted in apoptosis for about 80% of CFT-2 (homozygous for delta F508 deletion) cells and for 35-40% of CFT-1 (heterozygous) or normal cells. Our results suggest that Fas may mediate apoptosis in cystic fibrosis airway epithelium.

Leukotriene B4 (LTB4), an inflammatory mediator, is a potent chemoattractant for neutrophils (PMN) that plays an important role in the late reaction in asthma. Human airway epithelial cells (HAEC) can interact with PMN to increase LTB4 production. The aim of this study was to determine the influence of loratadine, an antihistaminic drug, on the production of LTB4 by PMN either alone or during interaction with transformed HAEC. The effect of tumour necrosis factor-alpha (TNF-alpha) was also examined. LTB4 production was measured by RP-HPLC after cell stimulation with calcium ionophore. Loratadine (0.25-25 microM) induced a significant and dose-dependent decrease of LTB4 production by PMN alone whereas it was up-regulated by TNF-alpha. As reported by others, we confirmed the increase of LTB4 release when PMN were cocultured with HAEC as compared to PMN alone. Addition of loratadine to HAEC before co-culture with PMN induced a significant decrease of LTB4 formation by cell interaction. This effect was noted when HAEC were washed following incubation with loratadine, demonstrating a direct action of the drug on this cell type. Moreover, the TNF-alpha-induced stimulation of LTB4 release that we demonstrated in PMN-HAEC interaction was also inhibited by loratadine. These results indicate that loratadine might reduce inflammatory reaction by a direct effect on PMN LTB4 production but also through an influence on HAEC during interaction with PMN.

We studied the incorporation of [3H]methyl from [3H]methyl-S-adenosylmethionine into leukocyte phospholipids. A higher incorporation in leukocytes from control subjects than from allergic subjects was noticed.