Poly(I:C) potentiates Bacillus Calmette-Guérin immunotherapy for bladder cancer.

Non-specific immunotherapy consisting of intravesical instillation of Bacillus Calmette-Guérin (BCG) is currently the best available treatment to prevent non-muscle-invasive bladder tumor recurrence and progression. This treatment however is suboptimal, and more effective immunotherapeutic approaches are needed. Toll-like receptors (TLRs) play a major role in the activation of the immune system in response to pathogens and danger signals but also in anti-tumor responses. We previously showed that human urothelial cells express functional TLRs and respond to TLR2 and TLR3 agonists. In this study, we analyzed the potential of polyinosinic:polycytidylic acid [poly(I:C)], a TLR3 agonist, to replace or complement BCG in the treatment of non-muscle-invasive bladder cancer. We observed that poly(I:C) had an anti-proliferative, cytotoxic, and apoptotic effect in vitro on two low-grade human bladder cancer cell lines, MGH-U3 and RT4. In MGH-U3 cells, poly(I:C) induced growth arrest at the G1-S transition. Poly(I:C) also increased the immunogenicity of MGH-U3 and RT4 cells, inducing the secretion of MHC class I molecules and of pro-inflammatory cytokines. By comparison, poly(I:C) had less in vitro impact on two high-grade human bladder cancer cell lines, 5637 and T24, and on MBT-2 murine high-grade bladder cancer cells. The latter can be used as an immunocompetent model of bladder cancer. The combination poly(I:C)/BCG was much more effective in reducing MBT-2 tumor growth in mice than either treatment alone. It completely cured 29% of mice and also induced an immunological memory response. In conclusion, our study suggests that adding poly(I:C) to BCG may enhance the therapeutic effect of BCG.

Toll-like receptors in normal and malignant human bladders.

PURPOSE: Toll-like receptors have a major role in the innate immune response. They are expressed by immune cells and some epithelial cells. To study the role of urothelial cells in the intrabladder innate immune response we analyzed toll-like receptor expression and functionality in normal and malignant urothelial cells. MATERIALS AND METHODS: Toll-like receptor 1 to 10 mRNA expression was analyzed using reverse transcriptase-polymerase chain reaction in 4 primary cultures of normal urothelium and 15 bladder cancer cell lines. Immunohistochemistry was used to detect toll-like receptor expression in 11 normal urothelial samples and 26 bladder tumors. Proinflammatory cytokine secretion by toll-like receptor agonist or bacillus Calmette-Guérin treated cultured cells was assessed by enzyme-linked immunosorbent assay. Mitogen-activated protein kinase phosphorylation was analyzed by Western blot and nuclear factor-κB localization was assessed by confocal microscopy. RESULTS: Expression of most toll-like receptor mRNA was detected in cultured normal or tumor urothelial cells. Expression of toll-like receptors 2 to 4, 5, 7 and 9 protein was detected in all normal urothelial samples and most nonmuscle invasive tumors, although its intensity was decreased in the latter. Expression was markedly decreased in muscle invasive tumors. Treatment with toll-like receptor 2 and 3 agonists showed the strongest inflammatory response in 2 primary cultures of normal urothelial cells and 3 bladder cancer cell lines. Toll-like receptor 2 and 3 functionality was confirmed by the nuclear translocation of nuclear factor-κB and the induction of phosphorylated c-Jun N-terminal kinase mitogen-activated protein-kinase. CONCLUSIONS: Toll-like receptors are expressed in normal urothelium and nonmuscle invasive bladder tumors. In cultured urothelial cells agonist inducible toll-like receptor 2 or constitutively expressed toll-like receptor 3 is functional. These data suggest the potential use of toll-like receptor agonists for antitumor immunotherapy of nonmuscle invasive tumors.

Refractoriness of hepatitis C virus internal ribosome entry site to processing by Dicer in vivo.

BACKGROUND: Hepatitis C virus (HCV) is a positive-strand RNA virus harboring a highly structured internal ribosome entry site (IRES) in the 5' nontranslated region of its genome. Important for initiating translation of viral RNAs into proteins, the HCV IRES is composed of RNA structures reminiscent of microRNA precursors that may be targeted by the host RNA silencing machinery. RESULTS: We report that HCV IRES can be recognized and processed into small RNAs by the human ribonuclease Dicer in vitro. Furthermore, we identify domains II, III and VI of HCV IRES as potential substrates for Dicer in vitro. However, maintenance of the functional integrity of the HCV IRES in response to Dicer overexpression suggests that the structure of the HCV IRES abrogates its processing by Dicer in vivo. CONCLUSION: Our results suggest that the HCV IRES may have evolved to adopt a structure or a cellular context that is refractory to Dicer processing, which may contribute to viral escape of the host RNA silencing machinery.

IL-8 secretion in primary cultures of prostate cells is associated with prostate cancer aggressiveness.

BACKGROUND: Chronic inflammation is believed to be a major factor in prostate cancer initiation and promotion and has been studied using prostate cancer cells and immortalized cell lines. However, little is known about the contribution of normal cells to the prostatic microenvironment and inflammation. We aim to study the contribution of normal prostate epithelial cells to prostate inflammation and to link the inflammatory status of normal cells to prostate cancer aggressiveness. MATERIALS AND METHODS: Short-term primary cell cultures of normal epithelial prostate cells were derived from prostate biopsies from 25 men undergoing radical prostatectomy, cystoprostatectomy, or organ donation. Cells were treated with polyinosinic:polycytidylic acid, a mimic of double-stranded viral RNA and a potent inducer of the inflammatory response. Secretion of interleukin (IL)-8 in the cell culture medium by untreated and treated cells was measured and we determined the association between IL-8 levels in these primary cell cultures and prostate cancer characteristics. The Fligner-Policello test was used to compare the groups. RESULTS: Baseline and induced IL-8 secretion were highly variable between cultured cells from different patients. This variation was not related to drug use, past medical history, age, or preoperative prostate-specific antigen value. Nonetheless, an elevated secretion of IL-8 from normal cultured epithelial cells was associated with prostate cancer aggressiveness (P=0.0005). CONCLUSION: The baseline secretion of IL-8 from normal prostate epithelial cells in culture is strongly correlated with cancer aggressiveness and may drive prostate cancer carcinogenesis. A better characterization of individual prostate microenvironment may provide a basis for personalized treatment and for monitoring the effects of strategies aimed at preventing aggressive prostate cancer.

Toll-like receptors in urothelial cells--targets for cancer immunotherapy.

Toll-like receptors (TLRs) have an important role in the activation of both innate and adaptive immunity in response to pathogens and danger signals. These receptors are expressed in immune cells and in some epithelia. They are expressed in the epithelium of the urinary bladder, where they actively participate in the fight against infection by uropathogens. TLR expression is decreased (although still evident) in bladder tumours, especially in non-muscle-invasive tumours. Intravesical immunotherapy with BCG to prevent recurrence of these tumours has been shown to involve the participation of three different TLRs (TLR2, TLR4, and TLR9). However, alternative therapies are needed as BCG fails in some patients and can sometimes cause severe adverse effects that are difficult to tolerate. In recent years, TLR2, TLR4, TLR7, and TLR9 agonists have been tested in vitro and in vivo for their ability to activate an antitumour immune response against bladder cancer. Promising results from these studies have led to the testing of TLR7 and TLR9 agonists in clinical trials.

High level of mature tumor-infiltrating dendritic cells predicts progression to muscle invasion in bladder cancer.

A prognostic value for tumor-associated macrophages (TAMs) and tumor-infiltrating dendritic cells (TIDCs) has been reported in many human cancers. The objective of this study is to determine the prognostic value of CD83(+) mature TIDCs and CD68(+) TAMs in non-muscle-invasive bladder cancer at first diagnosis. Immunohistochemistry staining was performed with anti-CD68 and anti-CD83 monoclonal antibodies on tissue sections from 93 formalin-fixed, paraffin-embedded tissue blocks from pTa and pT1 bladder tumors. A scoring index based on the average density of observed positive cells in the papillary axis, the stroma, lymphoid aggregates, and into tumor foci was calculated for each patient. Comparison of baseline characteristics with marker levels was done using Pearson χ(2) or Fisher exact test. Kaplan-Meier analyses and Cox regression models were fitted to evaluate the prognostic value of TIDCs and TAMs. The absence of both CD68(+) TAMs and CD83(+) TIDCs was associated with tumor recurrence. The presence of TIDCs was associated with a significant risk of progression to muscle-invasive cancer (hazard ratio, 8.253; P = .0179). Patients were risk stratified using age and TIDC score. Patients 70 years or older with a high score of TIDCs had a 56% progression-free survival after 6 years compared with 94% for patients younger than 70 years with a low score of TIDCs. None of 20 patients with a low score of TAMs progressed. These data indicate that the presence of mature TIDCs and possibly TAMs may help risk-stratify patients at the time of first diagnosis of non-muscle-invasive bladder cancer and may be useful in tailoring follow-up and treatment strategies.

Bladder tumor infiltrating mature dendritic cells and macrophages as predictors of response to bacillus Calmette-Guérin immunotherapy.

BACKGROUND: The clinical significance of tumor-infiltrating dendritic cells (TIDCs) and tumor-associated macrophages (TAMs) as markers of immune response has been reported for many cancers. OBJECTIVE: To measure tumor infiltration by CD83(+) dendritic cells (DCs) and CD68(+) macrophages in non-muscle-invasive urothelial cancer (NMIUC) prior to bacillus Calmette-Guérin (BCG) immunotherapy and to evaluate their significance in the response to immunotherapy. DESIGN, SETTING, AND PARTICIPANTS: Patients with NMIUC at high risk of recurrence and progression were recruited for a study on markers of the response to BCG. INTERVENTION: Patients were treated by transurethral resection followed by maintenance BCG. MEASUREMENTS: Immunohistochemical staining with anti-CD83 and anti-CD68 monoclonal antibodies on 53 and 46 NMIUC tumors, respectively, prior to BCG treatment. A scoring index was calculated based on the average density of positive cells within the papillary axis, the stroma, lymphoid aggregates, and infiltration into tumors. RESULTS AND LIMITATIONS: CD83(+) TIDCs were observed mostly within lymphoid aggregates. Multivariate Cox regression analysis showed that maintenance BCG (more than one maintenance cycle) was highly effective in patients with a low level of CD83(+) TIDCs at time of resection (hazard ratio [HR]: 0.035; p=0.002) but showed reduced efficacy in patients with a high level of CD83(+) TIDCs (HR: 0.87; p=0.810). A high level of infiltration by CD83(+) TIDCs slightly decreased the risk of recurrence in patients treated with one or no maintenance BCG cycle (HR: 0.4; p=0.117). In the same population, a strong infiltration of CD68(+) TAMs was associated with an increased risk of recurrence (HR: 3.8; p=0.013). CONCLUSIONS: These results suggest that patients with a high level of infiltration by CD83(+) TIDCs or CD68(+) TAMs do not respond as well to BCG immunotherapy. If confirmed in larger cohorts, the pretreatment level of infiltration by these cells may be useful to influence the choice of treatment strategy.