Localization of FOXP3-positive cells in renal cell carcinoma

Investigating the Role of FoxP3 in Renal Cell Carcinoma Metastasis with BAP1 or SEDT2 Mutation

Forkhead box protein P3 (FoxP3) primarily functions as the master regulator in regulatory T cells (Tregs) differentiation, but its high level of expression has also been found in tumor cells recently. The aim of our study was to clarify the role of FoxP3 in renal cell carcinoma (RCC) progression and metastasis. We verified the FoxP3 characteristic clinicopathological data from The Cancer Genome Atlas (TCGA) database using bioinformatics tools. Meanwhile, RNA sequencing was performed to determine the FoxP3 biofunction in RCC progression. Our results showed that high expression of FoxP3 was found in BAP1- or SETD2-mutant patients with RCC, and a higher FoxP3 expression was related to worse prognosis. However, there was no statistically significant relationship between the FoxP3 IHC score and RCC malignant progression owning to the limited number of patients in our tissue microarray. Using in vitro FoxP3 loss-of-function assays, we verified that silencing FoxP3 in 786-O and ACHN cells could inhibit the cell migration/invasion capability, which was consistent with the data from RNA sequencing in 786-O cells and from the TCGA datasets. Using an in vivo nude mice orthotopic kidney cancer model, we found that silencing FoxP3 could inhibit tumor growth. In conclusion, our study demonstrated that BAP1 or SEDT2 mutation could lead to higher expression of FoxP3 in RCC patients, and FoxP3 could eventually stimulate RCC cells' invasion and metastasis, which might indicate that FoxP3 could function as a potential oncogene in RCC progression.

Druggable Biomarkers Altered in Clear Cell Renal Cell Carcinoma: Strategy for the Development of Mechanism-Based Combination Therapy

Targeted therapeutics made significant advances in the treatment of patients with advanced clear cell renal cell carcinoma (ccRCC). Resistance and serious adverse events associated with standard therapy of patients with advanced ccRCC highlight the need to identify alternative 'druggable' targets to those currently under clinical development. Although the Von Hippel-Lindau (VHL) and Polybromo1 (PBRM1) tumor-suppressor genes are the two most frequently mutated genes and represent the hallmark of the ccRCC phenotype, stable expression of hypoxia-inducible factor-1α/2α (HIFs), microRNAs-210 and -155 (miR_S), transforming growth factor-beta (TGF-ß), nuclear factor erythroid 2-related factor 2 (Nrf2), and thymidine phosphorylase (TP) are targets overexpressed in the majority of ccRCC tumors. Collectively, these altered biomarkers are highly interactive and are considered master regulators of processes implicated in increased tumor angiogenesis, metastasis, drug resistance, and immune evasion. In recognition of the therapeutic potential of the indicated biomarkers, considerable efforts are underway to develop therapeutically effective and selective inhibitors of individual targets. It was demonstrated that HIF_S, miR_S, Nrf2, and TGF-ß are targeted by a defined dose and schedule of a specific type of selenium-containing molecules, seleno-L-methionine (SLM) and methylselenocystein (MSC). Collectively, the demonstrated pleiotropic effects of selenium were associated with the normalization of tumor vasculature, and enhanced drug delivery and distribution to tumor tissue, resulting in enhanced efficacy of multiple chemotherapeutic drugs and biologically targeted molecules. Higher selenium doses than those used in clinical prevention trials inhibit multiple targets altered in ccRCC tumors, which could offer the potential for the development of a new and novel therapeutic modality for cancer patients with similar selenium target expression. Better understanding of the underlying mechanisms of selenium modulation of specific targets altered in ccRCC could potentially have a significant impact on the development of a more efficacious and selective mechanism-based combination for the treatment of patients with cancer.

A comprehensive bioinformatics analysis of FOXP3 in nonsmall cell lung cancer

Fork head box p3 (FOXP3), the specific transcription factors of Tregs, not only in Tregs, but also expressed in cancer cells of certain malignant tumors. The histological positioning of FOXP3 in nonsmall cell lung cancer (NSCLC) and its biological significance are still unclear. This study aims to clarify the biological function of FOXP3 in NSCLC through bioinformatics analysis. Tumor immune estimation resource database was used to analyze the mRNA expression of FOXP3 in pan cancer, and to analyze the correlation between FOXP3 expression and tumor microenvironment cell infiltration. Overall survival and disease-free survival analyses were performed using a Kaplan-Meier plotter. Immunohistochemistry staining of FOXP3 was performed using human protein atalas (HPA) database, and immunofluorescence (IF) staining was used to verify gene expression and identify cell types. Protein-protein interaction (PPI) networks were drawn using STRING and visualized by Cytoscape. The functional and pathway enrichment analysis of FOXP3 used the DAVID database. In NSCLC, whether it is lung squamous cell carcinoma (P < .001) or lung adenocarcinoma (P < .001), FOXP3 is highly expressed in cancer tissue compared with normal tissue. Immunohistochemistry results showed that FOXP3 was mainly expressed in Tregs, but not in lung cancer tissues. IF staining showed that FOXP3 and CD3 (a marker of T cells) were co-expressed in immune cells. Moreover, survival analysis showed that high FOXP3 expression could be used as a predictor of poor overall survival (HR: 1.25, P = .00065) and disease-free survival (HR: 1.88, P = 1.1E-10) in patients with NSCLC. Next, we identified an important module containing 11 genes in the PPI network, including JUN, NFATC, STAT3, IRF4, IL2, IFGN, CTLA4, TNFRSF18, IL2A, KAT5, and FOXP3. KEGG signaling pathway was enriched in T cell receptor signaling pathway, Jak-STAT signaling pathway, cytokine-cytokine receptor interaction. Finally, we observed that FOXP3 expression correlated with infiltration of CD8 + T cells (R = 0.276, P = 5.90E-10), CD4 + T cells (R = 0.643, P = 6.81E-58), neutrophils (R = 0.525, P = 1.57E-35), and dendritic cells (R = 0.608, P = 1.35E-50) in lung adenocarcinoma, the same results were observed in lung squamous cell carcinoma. The infiltration of FOXP3-positive Tregs might promote the malignant progression of NSCLC, and targeted intervention of Tregs may be a potential treatment option for patients with NSCLC.

Regulatory T Cells: Barriers of Immune Infiltration Into the Tumor Microenvironment

Regulatory T cells (T_regs) are key immunosuppressive cells that promote tumor growth by hindering the effector immune response. T_regs utilize multiple suppressive mechanisms to inhibit pro-inflammatory responses within the tumor microenvironment (TME) by inhibition of effector function and immune cell migration, secretion of inhibitory cytokines, metabolic disruption and promotion of metastasis. In turn, T_regs are being targeted in the clinic either alone or in combination with other immunotherapies, in efforts to overcome the immunosuppressive TME and increase anti-tumor effects. However, it is now appreciated that T_regs not only suppress cells intratumorally via direct engagement, but also serve as key interactors in the peritumor, stroma, vasculature and lymphatics to limit anti-tumor immune responses prior to tumor infiltration. We will review the suppressive mechanisms that T_regs utilize to alter immune and non-immune cells outside and within the TME and discuss how these mechanisms collectively allow T_regs to create and promote a physical and biological barrier, resulting in an immune-excluded or limited tumor microenvironment.

Novel molecular signatures and potential therapeutics in renal cell carcinomas: Insights from a comparative analysis of subtypes

Renal cell carcinomas (RCCs) are among the highest causes of cancer mortality. Although transcriptome profiling studies in the last decade have made significant molecular findings on RCCs, effective diagnosis and treatment strategies have yet to be achieved due to lack of adequate screening and comparative profiling of RCC subtypes. In this study, a comparative analysis was performed on RNA-seq based transcriptome data from each RCC subtype, namely clear cell RCC (KIRC), papillary RCC (KIRP) and kidney chromophobe (KICH), and mutual or subtype-specific reporter biomolecules were identified at RNA, protein, and metabolite levels by the integration of expression profiles with genome-scale biomolecular networks. This approach revealed already-known biomarkers in RCCs as well as novel biomarker candidates and potential therapeutic targets. Our findings also pointed out the incorporation of the molecular mechanisms of KIRC and KIRP, whereas KICH was shown to have distinct molecular signatures. Furthermore, considering the Dipeptidyl Peptidase 4 (DPP4) receptor as a potential therapeutic target specific to KICH, several drug candidates such as ZINC6745464 were identified through virtual screening of ZINC molecules. In this study, we reported valuable data for further experimental and clinical efforts, since the proposed molecules have significant potential for screening and therapeutic purposes in RCCs.

Tumor immune microenvironment in non-muscle-invasive urothelial carcinoma of the bladder

Immunotherapy has gained significance in a variety of tumor types including advanced urothelial carcinoma. Noninvasive urothelial lesions have been treated with intravesical Bacillus-Calmette-Guerin (BCG) for decades. Given treatment failure in a subset of these tumors, ongoing clinical trials investigating the role of checkpoint inhibitors are actively pursued in this group of patients. The present study aims to delineate PD-L1, CD8, and FOXP3 expression in tumor microenvironment in non-muscle-invasive urothelial carcinoma samples obtained via sequential biopsies and to assess its potential role in predicting disease outcome. Cases with >1% and> 5% PD-L1 expression in tumor cells showed lower relative risk (RR) to recur at any subsequent biopsy compared with those with lower PD-L1 expression (RRs, 0.83 [P = .009] and 0.81 [P = .03], respectively). Cases with higher expression of FOXP3 in peritumoral lymphocytes were at lower risk for tumor grade progression at any biopsy (RR, 0.2; P = .02). Tumors with FOXP3/CD8 expression ratio of >1 in intratumoral lymphocytes had lower risk of grade progression (RR, 0.28; P = .04). Although higher number of FOXP3-, CD8-, and PD-L1-positive lymphocytes were encountered after BCG treatment, the findings did not reach statistical significance. In patients without BCG treatment, PD-L1 expression in tumor cells and peritumoral lymphocytes varied across serial biopsies, suggesting the need for additional approaches to assess eligibility for immunotherapy in non-muscle-invasive urothelial carcinoma patients.

The current status of immunobased therapies for metastatic renal-cell carcinoma

The management of metastatic renal-cell carcinoma (mRCC) represents an important clinical challenge. Since being approved in the early 1990s, aspecific immunotherapy has been a mainstay of treatment for mRCC and the only therapy that has demonstrated long-term cures for mRCC. However, in recent times there have been landmark advances made in the field of specific immunotherapy for a number of malignancies, including kidney cancer. This review outlines the range of immunobased agents currently available for the treatment of mRCC.

Hyper IgE Syndrome and Renal Cell Carcinoma

Hyper IgE Syndrome (HIES) is an immunodeficiency disorder characterized by increased serum levels of IgE, eczema, and recurrent cutaneous and pulmonary infections. In this report, we present, to our knowledge, the first documented case of renal cell carcinoma (RCC) found in a patient with HIES. The patient received infectious disease clearance prior to obtaining a partial nephrectomy which revealed clear cell histology. Both HIES and RCC have an immunological basis for their pathophysiology and may involve common pathways. Further studies may provide insight into any possible link and clinicians should be mindful of immunocompromised patients who present with risk factors for genitourinary malignancy.

VHL-dependent alterations in the secretome of renal cell carcinoma: Association with immune cell response?

Secreted proteins could modulate the interaction between tumor, stroma and immune cells within the tumor microenvironment thereby mounting an immunosuppressive tumor microenvironment. In order to determine the secretome-mediated, von Hippel Lindau (VHL)-regulated cross-talk between tumor cells and T lymphocytes peripheral blood mononuclear cells (PBMC) from healthy donors were either cultured in conditioned media obtained from normoxic and hypoxic human VHL-deficient renal cell carcinoma (RCC) cell line (786-0^VHL−) and its wild type (wt) VHL-transfected counterpart (786-0^VHL+) or directly co-cultured with both cell lines. An increased T cell proliferation was detected in the presence of 786-0^VHL+-conditioned medium. By applying a quantitative proteomic-based approach using differential gel electrophoresis followed by mass spectrometry fourteen proteins were identified to be differentially expressed within the secretome of 786-0^VHL− cells when compared to that of 786-0^VHL+ cells. All proteins identified were involved in multiple tumor-associated biological functions including immune responses. Functional studies on manganese superoxide dismutase 2 (MnSOD2) demonstrated that it was a regulator of T cell activation-induced oxidative signaling and cell death. Direct effects of soluble MnSOD2 on the growth properties and interleukin 2 (IL-2) secretion of T cells could be demonstrated underlining the critical role of extracellular MnSOD2 levels for T cell proliferation and activation.

The ratio of CD8 to Treg tumor-infiltrating lymphocytes is associated with response to cisplatin-based neoadjuvant chemotherapy in patients with muscle invasive urothelial carcinoma of the bladder

Introduction: Randomized controlled trials of platinum-based neoadjuvant chemotherapy (NAC) for bladder cancer have shown that patients who achieve a pathologic response to NAC exhibit 5 y survival rates of approximately 80–90% while NAC resistant (NR) cases exhibit 5 y survival rates of approximately 30–40%. These findings highlight the need to predict who will benefit from conventional NAC and the need for plausible alternatives. Methods: The pre-treatment biopsy tissues from a cohort of 41 patients with muscle invasive bladder who were treated with NAC were incorporated in tissue microarray and immunohistochemistry for PD-L1, CD8, and FOXP3 was performed. Percentage of PD-L1 positive tumor cells was measured. Tumor-infiltrating lymphocytes (TIL) densities, along with CD8 and Treg-specific TILs, were measured. Results: TIL density was strongly correlated with tumor PD-L1 expression, consistent with the mechanism of adaptive immune resistance in bladder cancer. Tumor cell PD-L1 expression was not a significant predictor of response. Neither was the CD8 nor Treg TIL density associated with response. Intriguingly though, the ratio of CD8 to Treg TIL densities was strongly associated with response (p = 0.0003), supporting the hypothesis that the immune system plays a role in the response of bladder cancer to chemotherapy. Discussion: To our knowledge, this is the first report in bladder cancer showing that the CD8 to Treg TIL density in the pre-treatment tissues is predictive for conventional NAC response. These findings warrant further investigations to both better characterize this association in larger cohorts and begin to elucidate the underlying mechanism(s) of this phenomenon.

Modification of the tumor microenvironment as a novel target of renal cell carcinoma therapeutics

To move forward with immunotherapy, it is important to understand how the tumor microenvironment generates systemic immunosuppression in patients with renal cell carcinoma (RCC) as well as in patients with other types of solid tumors. Even though antigen discovery in RCC has lagged behind melanoma, recent clinical trials have finally authenticated that RCC is susceptible to vaccine-based therapy. Furthermore, judicious coadministration of cytokines and chemotherapy can potentiate therapeutic responses to vaccine in RCC and prolong survival, as has already proved possible for melanoma. Although high-dose interleukin 2 immunotherapy has been superseded as first-line therapy for RCC by promiscuous receptor tyrosine kinase inhibitors (rTKIs) such as sunitinib, sunitinib itself is a potent immunoadjunct in animal tumor models. A reasonable therapeutic goal is to unite antiangiogenic strategies with immunotherapy as first-line therapy for RCC. This strategy is equally appropriate for testing in all solid tumors in which the microenvironment generates immunosuppression. A common element of RCC and pancreatic, colon, breast, and other solid tumors is large numbers of circulating myeloid-derived suppressor cells (MDSCs), and because MDSCs elicit regulatory T cells rather than vice versa, gaining control over MDSCs is an important initial step in any immunotherapy. Although rTKIs like sunitinib have a remarkable capacity to deplete MDSCs and restore normal T-cell function in peripheral body compartments such as the bloodstream and the spleen, such rTKIs are effective only against MDSCs, which are engaged in phospho-STAT3-dependent programming (pSTAT3+). Unfortunately, rTKI-resistant pSTAT3- MDSCs are especially apt to arise within the tumor microenvironment itself, necessitating strategies that do not rely exclusively on STAT3 disruption. The most utilitarian strategy to gain control of both pSTAT3+ and pSTAT3- MDSCs may be to exploit the natural differentiation pathway, which permits MDSCs to mature into tumoricidal macrophages (TM1) via such stimuli as Toll-like receptor agonists, interferon γ, and CD40 ligation. Overall, this review highlights the mechanisms of immune suppression used by the different regulatory cell types operative in RCC as well as other tumors. It also describes the different therapeutic strategies to overcome the suppressive nature of the tumor microenvironment.

Regulatory T-cell differentiation and their function in immune regulation

Regulatory T-cells (Treg) represent a subset of CD4+ T-cells characterized by high suppressive capacity, which can be generated in the thymus or induced in the periphery. The deleterious phenotype of the Scurfy mouse, which develops an X-linked lymphoproliferative disease resulting from defective T-cell tolerance, clearly demonstrates the importance of Treg cells for the maintenance of immune homeostasis. Although significant progress has been achieved, much information regarding the development, characteristics and function of Treg cells remain lacking. This chapter highlights the most recent discoveries in the field of Treg biology, focusing on the development and role of this cell subset in the maintenance of immune balance.