Bacillus Calmette Guerin induces fibroblast activation both directly and through macrophages in a mouse bladder cancer model

The dynamic roles of the bladder tumour microenvironment

Bladder cancer is a prevalent but currently understudied cancer type and patient outcomes are poor when it progresses to the muscle-invasive stage. Current research in bladder cancer focuses on the genetic and epigenetic alterations occurring within the urothelial cell compartment; however, the stromal compartment receives less attention. Dynamic changes and intercellular communications occur in the tumour microenvironment (TME) of the bladder - a new concept and niche that we designate as the bladder TME (bTME) - during tumour evolution, metastatic progression and in the context of therapeutic response. Collagens and their cognate receptors, the discoidin domain receptors, have a role in various steps of the metastatic cascade and in immune checkpoint resistance. Furthermore, the presence of another TME niche, the metastatic TME (met-TME), is a novel concept that could support divergent progression of metastatic colonization in different organs, resulting in distant metastases with distinct characteristics and genetics from the primary tumour. The stroma has divergent roles in mediating therapeutic response to BCG immunotherapy and immune checkpoint inhibitors, as well as conventional chemotherapy or trimodality therapy (that is, maximal transurethral resection of bladder tumour, chemotherapy and radiotherapy). The local bTME and distant met-TME are currently conceptually and therapeutically unexploited niches that should be actively investigated. New biological insights from these TMEs will enable rational design of strategies that co-target the tumour and stroma, which are expected to improve the outcomes of patients with advanced bladder cancer.

Tumor-Associated Macrophages in Bladder Cancer: Biological Role, Impact on Therapeutic Response and Perspectives for Immunotherapy

Tumor-associated macrophages (TAMs) are one of the most abundant infiltrating immune cells of solid tumors. Despite their possible dual role, i.e., pro- or anti-tumoral, there is considerable evidence showing that the accumulation of TAMs promotes tumor progression rather than slowing it. Several strategies are being developed and clinically tested to target these cells. Bladder cancer (BCa) is one of the most common cancers, and despite heavy treatments, including immune checkpoint inhibitors (ICIs), the overall patient survival for advanced BCa is still poor. TAMs are present in bladder tumors and play a significant role in BCa development. However, few investigations have analyzed the effect of targeting TAMs in BCa. In this review, we focus on the importance of TAMs in a cancerous bladder, their association with patient outcome and treatment efficiency as well as on how current BCa treatments impact these cells. We also report different strategies used in other cancer types to develop new immunotherapeutic strategies with the aim of improving BCa management through TAMs targeting.

Effect of nitric oxide inhibition in Bacillus Calmette-Guerin bladder cancer treatment

BACKGROUND

Bacillus Calmette-Guerin (BCG) is the standard treatment for patients with high-risk non-muscle invasive bladder cancer (BC). Despite its success, about 30-50% of patients are refractory. It was reported that inducible nitric oxide synthase (iNOS) tumor expression is presented in 50% of human BC, associated with bad prognosis and BCG failure.

OBJECTIVE

to evaluate in human bladder tumors the association between iNOS expression and the tumor microenvironment focusing on the immunosuppressive protein S100A9. Also, investigate in a preclinical murine MB49-BC model the tumor immunoresponse induced by BCG in combination with the nitric oxide production inhibitor l-NAME.

RESULTS

In human bladder tumors, we detected a positive association between iNOS and S100A9 tumor expression, suggesting a relationship between both immunomodulatory proteins. We also found a positive correlation between iNOS tumor expression and the presence of S100A9⁺ tumor-infiltrating cells, suggesting an immunosuppressive tumor microenvironment induced by the nitric oxide production. Using the subcutaneous murine BC model, we show that similarly to the human pathology, MB49 tumors constitutively expressed iNOS and S100A9 protein. MB49 tumor-bearing mice presented an immunosuppressive systemic profile characterized by fewer cytotoxic cells (CD8⁺ and NK) and higher suppressor cells (Treg and myeloid-derived suppressor cells -MDSC-) compared to normal mice. BCG treatment reduced tumor growth, increasing local CD8⁺-infiltrating cells and induced a systemic increase in CD8⁺ and a reduction in Treg. BCG combined with l-NAME, significantly reduced tumor growth compared to BCG alone, diminishing iNOS and S100A9 tumor expression and increasing CD8⁺-infiltrating cells in tumor microenvironment. This local response was accompanied by the systemic increase in CD8⁺ and NK cells, and the reduction in Treg and MDSC, even more than BCG alone. Similar results were obtained using the orthotopic BC model, where an increase in specific cytotoxicity against MB49 tumor cells was detected.

CONCLUSION

The present study provides preclinical information where NO inhibition in iNOS-expressing bladder tumors could contribute to improve BCG antitumor immune response. The association between iNOS and S100A9 in human BC supports the hypothesis that iNOS expression is a negative prognostic factor and a promising therapeutic target.

Inhibition of breast tumor growth by N(G)-nitro-l-arginine methyl ester (l-NAME) is accompanied by activation of fibroblasts

Nitric Oxide (NO) is involved in many physiological and pathological processes. It is generated by a family of NO synthases (NOS), being the inducible isoform, iNOS, responsible for higher amounts of NO. Here, we report that pharmacological inhibition of NO production by l-NAME reduces both viability and MAPK activated signalling pathways in iNOS positive human and murine cancer cell lines. In vivo, using syngeneic models, in parallel with tumor reduction induced by l-NAME, collagen deposition and α-SMA positive stromal cells are observed. This observation takes place only when tumor cells express iNOS. In vitro, l-NAME induces viability and differentiation on fibroblast. Our results reveal that NO inhibition contributes to stimulate proliferation and activation of fibroblasts in parallel with tumor reduction of iNOS positive breast cancer.

Bacillus Calmette-Guerin improves local and systemic response to radiotherapy in invasive bladder cancer

BACKGROUND

A key factor contributing to radio-resistance in conservative invasive bladder cancer (BCa) treatment is tumor hypoxia and a strategy to overcome it is to trigger the production of nitric oxide (NO). On the other hand, ionizing radiation (IR) applied to a primary tumor can induce immunogenic cell death which may set off a cytotoxic immune response against the primary tumor and its metastasis.

PURPOSE

To study in vitro and in vivo, the role of BCG as a local sensitizer to overcome hypoxia-associated radio-resistance through the production of NO, and as an immune-stimulator to be used in combination with IR to generate a systemic response for invasive BCa treatment.

MATERIALS AND METHODS

We selected the invasive murine BCa cell line MB49-I which expresses inducible NO synthase and produces NO, cultured in vitro in 2D and 3D models, and inoculated in vivo in the subcutaneous of syngeneic mice.

RESULTS

in vitro, multicellular murine invasive spheroids mimicked in vivo central tumor necrosis. BCG pre-treatment radio-sensitized spheroids through the induction of NO production, while no effect was shown in monolayers. In vivo, not only did BCG improve the local response to IR but it also decreased the metastatic spread and promoted the development of abscopal effect/rejection of a second tumor.

CONCLUSION

Since BCG has already and successfully been used for the treatment of non-invasive BCa and it improves the response to ionizing radiation in invasive BCa, these results are translational relevant to be analyzed in patients with this pathology.

Homology modeling and docking studies of ENPP4: a BCG activated tumoricidal macrophage protein

BACKGROUND

The 3D structure and functions of ENPP4, a protein expressed on the surface of Bacillus Calmette-Guerin (BCG)-activated macrophages, are unknown. In this study, we analyzed the 3D structure of ENPP4 and determined its tumoricidal effects on MCA207 cells.

RESULTS

Homology modeling showed that Arg305, Tyr341, Asn291, and Asn295 are important residues in substrate, adenosine triphosphate (ATP), binding. A molecular dynamics study was also carried out to study the stability of ENPP4 (including zinc atoms) as well as its ligand-enzyme complex. BCG increased ENPP4 expression in macrophages, and specific blocking of ENPP4 in BCG-activated macrophages (BAMs) significantly reduced their cytotoxicity against MCA207 cells.

CONCLUSIONS

These results indicate that zinc remains inside the ENPP4 protein, a BCG activated tumoricidal macrophage protein, throughout the simulation. Important information for the design of new inhibitors was obtained.

NMAAP1 Expressed in BCG-Activated Macrophage Promotes M1 Macrophage Polarization

Macrophages are divided into two subpopulations: classically activated macrophages (M1) and alternatively activated macrophages (M2). BCG (Bacilli Calmette-GuC)rin) activates disabled naC/ve macrophages to M1 macrophages, which act as inflammatory, microbicidal and tumoricidal cells through cell-cell contact and/or the release of soluble factors. Various transcription factors and signaling pathways are involved in the regulation of macrophage activation and polarization. We discovered that BCG-activated macrophages (BAM) expressed a new molecule, and we named it Novel Macrophage Activated Associated Protein 1 (NMAAP1). The current study found that the overexpression of NMAAP1 in macrophages results in M1 polarization with increased expression levels of M1 genes, such as inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-N1), Interleukin 6 (IL-6), Interleukin 12 (IL-12), Monocyte chemoattractant protein-1 (MCP-1) and Interleukin-1 beta (IL-1N2), and decreased expression of some M2 genes, such as Kruppel-like factor 4 (KLF4) and suppressor of cytokine signaling 1 (SOCS1), but not other M2 genes, including arginase-1 (Arg-1), Interleukin (IL-10), transforming growth factor beta (TGF-N2) and found in inflammatory zone 1 (Fizz1). Moreover, NMAAP1 overexpression in the RAW264.7 cell line increased cytotoxicity against MCA207 tumor cells, which depends on increased inflammatory cytokines rather than cell-cell contact. NMAAP1 also substantially enhanced the phagocytic ability of macrophages, which implies that NMAAP1 promoted macrophage adhesive and clearance activities. Our results indicate that NMAAP1 is an essential molecule that modulates macrophages phenotype and plays an important role in macrophage tumoricidal functions.

The delicate balance of macrophages in colorectal cancer; their role in tumour development and therapeutic potential

Most tumours are heavily infiltrated by immune cells. This has been correlated with either a good or a bad patient prognosis, depending on the (sub) type of immune cells. Macrophages represent one of the most prominent leukocyte populations in the majority of tumours. Functions of macrophages range from cytotoxicity, to stimulation of tumour growth by secretion of cytokines, growth and angiogenic factors, or suppressing immune responses. In most tumours macrophages are described as cells with immune suppressing, and wound healing properties, which aids tumour development. Yet, increasing evidence shows that macrophages are potent inhibitors of tumour growth in colorectal cancer. Macrophages in this respect show high plasticity. The presence of high macrophage numbers in the tumour may therefore become advantageous, if cells can be reprogrammed from tumour promoting macrophages into potent effector cells. Enhancing cytotoxic properties of macrophages by microbial products, pro-inflammatory cytokines or monoclonal antibody therapy are promising possibilities, and are currently tested in clinical trials.

FGFR3 Down-Regulation is Involved in bacillus Calmette-Guérin Induced Bladder Tumor Growth Inhibition

PURPOSE

Bacillus Calmette-Guérin is the standard treatment for patients with nonmuscle invasive high histological grade bladder cancer. Previously we found that bacillus Calmette-Guérin induces murine bladder cancer MB49 cell death in vitro and in vivo, generating tissue remodeling, which involves the release of fibroblast growth factor (FGF)-2.

MATERIALS AND METHODS

We studied the effect of bacillus Calmette-Guérin treatment on FGF-2 and FGF receptor (FGFR) expression in bladder cancer.

RESULTS

In vitro FGF-2 increased MB49 cell proliferation but did not reverse bacillus Calmette-Guérin induced cell death. Increased FGF-2 expression was detected after bacillus Calmette-Guérin treatment. Moreover MB49 cells expressed high FGFR3 levels, which decreased after treatment. Similar results were observed in human T24 bladder cancer cells. In vivo MB49 tumors expressed higher FGFR3 levels than normal urothelium. Tumor FGFR3 decreased after treatment and correlated with tumor growth inhibition in response to bacillus Calmette-Guérin. In a pilot bioassay using 11 human bladder tumors treated ex vivo with bacillus Calmette-Guérin we found a subgroup of 41% of patients in whom FGFR3 was decreased after treatment.

CONCLUSIONS

Based on bladder cancer murine model results we infer that down-regulation of FGFR3 is a predictive marker of a good response to bacillus Calmette-Guérin therapy. The decrease in FGFR3 in response to bacillus Calmette-Guérin occurred not only in a murine model but also in a human bladder cancer cell line and in some patient samples. More patients and increased followup are needed to establish the predictive role of FGFR3 as a marker in human bladder cancer.

iNOS expression and NO production contribute to the direct effects of BCG on urothelial carcinoma cell biology

OBJECTIVES

Evidence suggests that oxidative stress occurring as a consequence of inducible nitric oxide synthase/nitric oxide (iNOS/NO) contributes to the biologic effects of bacille Calmette-Guérin (BCG). Objective of this study is to examine iNOS expression, NO production, and the biologic effect of NO on established intermediate end points for the human urothelial carcinoma cell response to BCG.

MATERIALS AND METHODS

Quantitative reverse transcriptase-polymerase chain reaction and real-time measurement of NO was used to assess iNOS and NO production, respectively, in 2 human urothelial carcinoma (UC) cell lines, in response to BCG. The effect of blocking NO production using the specific iNOS inhibitor 1400W was determined for multiple intermediate end points characterizing BCG's direct effects on tumor cell biology. Activation of nuclear factor kappa B and nuclear factor (erythroid-derived 2)-like 2 signaling pathways, transactivation of genes, including p21, CD54, IL6, IL8, CXCL1, CXCL3, CCL20, and cytotoxicity, as measured by vital dye exclusion, lactate dehydrogenase release, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay were measured in response to BCG with and without iNOS inhibition.

RESULTS

Exposure of UC cells to BCG significantly increased both iNOS expression and NO production. Inhibition of iNOS activity with 1400W significantly inhibited BCG's direct biologic effect on UC cells for all of the end points evaluated.

CONCLUSIONS

iNOS expression, NO production, and the associated oxidative stress play a central role in the response of UC cells to BCG exposure. Manipulation of oxidative stress may afford an opportunity to enhance the antitumor effects of BCG.

Role of peroxisome proliferator activated receptor-gamma in bacillus Calmette-Guérin bladder cancer therapy

PURPOSE

We evaluated the effects of combined PPARg agonist with bacillus Calmette-Guérin in bladder cancer growth in vitro and in vivo, focusing on the tissue remodeling mechanisms induced by bacillus Calmette-Guérin.

MATERIALS AND METHODS

PPARs are a superfamily of nuclear receptors that are transcription factors activated by ligands. Activation of PPARg, the γ subtype, causes proliferation inhibition or differentiation of tumor cells. Previously, we reported that the inhibition of murine bladder tumor growth induced by bacillus Calmette-Guérin, which is the standard treatment for patients with nonmuscle invasive, high grade bladder cancer, increased PPARg expression in vitro and in vivo. In vitro the cell growth inhibition induced by bacillus Calmette-Guérin was enhanced by the PPARg agonist 15-d-PGJ2, raising the possibility that PPARg activation may be a therapeutic modality for this disease.

RESULTS

In MB49 cells bacillus Calmette-Guérin and 15-d-PGJ2 induced PPARg expression, nuclear translocation and transcriptional activity. In vivo bacillus Calmette-Guérin reduced tumor size, an effect that was partially reversed when bacillus Calmette-Guérin was combined with the PPARg agonist rosiglitazone. The same result was found when we analyzed the effect of the PPARg antagonist BADGE (Fluka Chemical, Buchs, Switzerland) combined with bacillus Calmette-Guérin. Analysis of the activation of macrophages and fibroblasts demonstrated that rosiglitazone inhibited the tissue remodeling mechanisms induced by bacillus Calmette-Guérin.

CONCLUSIONS

Results suggest that PPARg is involved in the antitumor action of bacillus Calmette-Guérin. However, exogenous PPARg agonists would not be a favorable therapeutic modality because they can inhibit the tissue remodeling needed for an overall satisfactory bacillus Calmette-Guérin response.

Inducible nitric oxide synthase and PPARγ are involved in bladder cancer progression

PURPOSE

We evaluated the role of inducible nitric oxide synthase and PPARγ as prognostic factors for bladder cancer.

MATERIALS AND METHODS

Inducible nitric oxide synthase and PPARγ were evaluated by Western blot and immunohistochemistry in a mouse bladder cancer model of nonmuscle invasive and invasive MB49-I tumor cells, and in human bladder cancer samples.

RESULTS

Inducible nitric oxide synthase expression was negative in mouse normal urothelium and higher in invasive than in noninvasive MB49 tumors. In vitro inducible nitric oxide synthase activity, determined as nitrite, was higher in MB49-I than in MB49 cells (p <0.001). In human samples expression was also associated with tumor invasion. Nuclear PPARγ expression was negative in normal mouse urothelium but higher in nonmuscle invasive MB49 than in MB49-I tumors. Similarly in human tumors low PPARγ was associated with poor prognosis factors, such as high histological grade (p = 0.0160) and invasion status (p = 0.0352). A positive correlation was noted between inducible nitric oxide synthase and PPARγ in low histological grade and nonmuscle invasive tumors (Pearson correlation index 0.6368, p = 0.0351, 0.4438 and 0.0168, respectively). As determined by gene reporter assay, PPARγ activity was induced by nitric oxide only in nonmuscle invasive MB49 cells (p <0.001).

CONCLUSIONS

Results suggest that increased PPARγ controls inducible nitric oxide synthase expression at early tumor stages. However, regulation is lost at advanced tumor stages, when the increase in inducible nitric oxide synthase and the decrease in PPARγ seem to be associated with bladder cancer progression.

Preparation and identification of a novel immunomodulator composed of muramyl dipeptide and anti-CD10 monoclonal antibody for treatment of minimal residual disease in acute leukemia children

Targeted therapy is a potentially useful approach for antileukemic therapy, in particular eliminating minimal residual disease (MRD) to prevent tumor relapse. In this study, the immunomodulator (MDP-Ab) was constructed by coupling anti-CD10 monoclonal antibody (MAb) and muramyl dipeptide (MDP) using heterobifunctional reagent SPDP and the activity of MDP-Ab through dendritic cells (DCs)-based immunotherapy was identified in targeted therapy for leukemia. Results showed that the molecular ratio of purified MDP-Ab immunomodulator was about 2:1 according to electrospray ionization mass spectrometry (ESI-MS). The immunoreactivity and specificity of the new immunomodulator on CD10 antigen was identical to that of unconjugated native anti-CD10 MAb. The immunomodulatory effect of MDP-Ab immunoconjugate on peripheral blood dendritic cells (PBDCs) from children with acute lymphoblastic leukemia (ALL) exhibited upregulated expression of HLA-DR, co-stimulatory marker (CD80 and CD86) and maturity marker (CD83), increased cytokine secretion (interleukin-12, IL-12) and enhanced autostimulatory activity. These results in vitro suggested that MDP-Ab immunoconjugate may be a suitable candidate for targeting trials and support the further development of vaccination with the new immunomodulator-triggered DCs as a post-remission treatment to prevent relapse in ALL children.