Rb/E2F1 regulates the innate immune receptor Toll-like receptor 3 in epithelial cells

Immune Checkpoint Blockade Outcome in Small-Cell Lung Cancer and Its Relationship With Retinoblastoma Mutation Status and Function

PURPOSE

Immune checkpoint blockade (ICB) in conjunction with chemotherapy is approved for the treatment of extensive-stage small-cell lung cancer (SCLC). Although specific genomic abnormalities such as KEAP1 and STK11 gene mutations are associated with resistance to ICB in non-SCLC, no genomic abnormality has been found in association with resistance to ICB in SCLC.

MATERIALS AND METHODS

We first analyzed a retrospective cohort of 42 patients with SCLC treated with single-agent ICB or ICB combination (data set A). We then validated our results in a large prospective clinical trial of 460 patients (CheckMate 032, data set B). DNA and RNA sequencing were performed.

RESULTS

In data set A, patients treated with ICB with RB1 wild-type (WT) had a median overall survival (OS) of 23.1 months (95% CI, 9 to 37.5), whereas the RB1 mutant OS was 5 months (95% CI, 2.5 to 26; P = .04). Differentially expressed gene analysis between RB1 mutant and RB1 WT samples indicated the enrichment of downregulated immune-related genes and an immune exclusion phenotype among RB1 mutant but not in the RB1 WT tumor samples. We then assessed results from 460 patients enrolled in CheckMate 032, a trial of nivolumab (NIVO) or NIVO + ipilimumab only in SCLC. In this large cohort, RB1 WT patients had significantly improved outcome with NIVO therapy compared with mutant patients (hazard ratio, 1.41; 95% CI, 1.02 to 2.01; P = .041). High RB1 loss-of-function (LOF) signature scores significantly associated with neuroendocrine subtypes (ASCL1 and NeuroD1). However, neuroendocrine subtypes did not associate with OS. Remarkably, patients with lower RB1 LOF scores had longer OS following treatment with NIVO.

CONCLUSION

SCLC patients with RB1 WT status or lower RB1 LOF signature scores by transcriptomics have better outcomes with ICB monotherapy.

Viral and cellular oncogenes promote immune evasion

Thirteen percent of cancers worldwide are associated with viral infections. While many human oncogenic viruses are widely endemic, very few infected individuals develop cancer. This raises the question why oncogenic viruses encode viral oncogenes if they can replicate and spread between human hosts without causing cancer. Interestingly, viral infection triggers innate immune signaling pathways that in turn activate tumor suppressors such as p53, suggesting that tumor suppressors may have evolved not primarily to prevent cancer, but to thwart viral infection. Here, we summarize and compare several major immune evasion strategies used by viral and non-viral cancers, with a focus on oncogenes that play dual roles in promoting tumorigenicity and immune evasion. By highlighting important and illustrative examples of how oncogenic viruses evade the immune system, we aim to shed light on how non-viral cancers avoid immune detection. Further study and understanding of how viral and non-viral oncogenes impact immune function could lead to improved strategies to combine molecular therapies targeting oncoproteins in combination with immunomodulators.

TLR3 Serves as a Prognostic Biomarker and Associates with Immune Infiltration in the Renal Clear Cell Carcinoma Microenvironment

Background

Clear cell renal cancer (KIRC) is one of the most common cancers globally, with a poor prognosis. TLRs play a vital role in anticancer immunity and the regulation of the biological progress of tumour cells. However, the precise role of TLRs in KIRC is still ambiguous.

Methods

Various bioinformatics analysis and clinical validation of tissues were performed to evaluate the prognostic value of TLRs and their correlation with immune infiltration in KIRC.

Results

The expression of TLR2/3/7/8 was increased at both mRNA and protein levels in KIRC. TLRs in KIRC were involved in the activation of apoptosis, EMT, RAS/MAPK, and RTK pathways, as well as the inhibition of the cell cycle and the hormone AR pathway. Drug sensitivity analysis revealed that high expression of TLR3 and low expression of TLR7/9/10 were resistant to most of the small molecules or drugs from CTRP. Enrichment analyses showed that TLRs were mainly involved in innate immune response, toll-like receptor signalling pathway, NF-kappa B signalling pathway, and TNF signalling pathway. Furthermore, a high-level TLR3 expression was associated with a favourable prognosis in KIRC. Validation research further confirmed that TLR3 expression was increased in KIRC tissues, and high TLR3 levels were associated with poor overall survival. Moreover, TLR3 in KIRC showed a positive association with an abundance of immune cells, including B-cells, CD4+ T-cells, CD8+ T-cells, macrophage, neutrophils, and dendritic cells, and the expression of the immune biomarker sets. Several TLR3-associated kinase, miRNA, or transcription factor targets were also identified in KIRC.

Conclusion

Our results indicate that TLR3 serves as a prognostic biomarker and associated with immune infiltration in KIRC. This work lays a foundation for further studies on the role of TLR3 in the carcinogenesis and progression of KIRC.

TYK2 is a prognostic biomarker and associated with immune infiltration in the lung adenocarcinoma microenvironment

BACKGROUND

Lung adenocarcinoma (LUAD) remains a major disease with high morbidity and mortality. The Janus kinases (JAKs) play a significant part in cellular biological process, inflammation and immunity. The role of JAK family in LUAD is still ambiguous.

METHODS

Various bioinformatics web portals were applied to explore the prognostic value of JAK family and their correlation with immune infiltration in LUAD.

RESULTS

JAK1/2 was downregulated, whereas JAK3/TYK2 was upregulated in patients with LUAD compared with the healthy controls in subgroup analyses based on gender, age, smoking habits, cancer stage, TP53 mutation status, and nodal metastasis status. Drug sensitivity indicated that low expression of JAK3 and TYK2 were resistant to most of the small molecules or drugs. High TYK2 expression was associated with favorable overall survival and relapse free survival in LUAD. Moreover, univariate and multivariate analysis revealed that clinical stage, lymphatic node metastasis and TYK2 expression were the independent factors affecting the prognosis of LUAD patients. TYK2 expression in LUAD patients was positively associated with the abundance of immune cells (B cells, CD8+ T cells, CD4+ T cells, neutrophils, and dendritic cells) and immune biomarker sets. Moreover, TYK2 was mainly involved in RNA binding, transcriptional mis-regulation in cancer and cell cycles. We also identified several TYK2-associated miRNA or transcription factor targets in LUAD.

CONCLUSION

Our results indicated that TYK2 was a biomarker and associated with prognosis and immune infiltration in LUAD, laying a foundation for further study about the role of TYK2 in the carcinogenesis and progression of LUAD.

Germline genetic contribution to the immune landscape of cancer

Understanding the contribution of the host's genetic background to cancer immunity may lead to improved stratification for immunotherapy and to the identification of novel therapeutic targets. We investigated the effect of common and rare germline variants on 139 well-defined immune traits in ∼9000 cancer patients enrolled in TCGA. High heritability was observed for estimates of NK cell and T cell subset infiltration and for interferon signaling. Common variants of IFIH1, TMEM173 (STING1), and TMEM108 were associated with differential interferon signaling and variants mapping to RBL1 correlated with T cell subset abundance. Pathogenic or likely pathogenic variants in BRCA1 and in genes involved in telomere stabilization and Wnt-β-catenin also acted as immune modulators. Our findings provide evidence for the impact of germline genetics on the composition and functional orientation of the tumor immune microenvironment. The curated datasets, variants, and genes identified provide a resource toward further understanding of tumor-immune interactions.

Unveiling Interindividual Variability of Human Fibroblast Innate Immune Response Using Robust Cell-Based Protocols

The LabEx Milieu Interieur (MI) project is a clinical study centered on the detailed characterization of the baseline and induced immune responses in blood samples from 1,000 healthy donors. Analyses of these samples has lay ground for seminal studies on the genetic and environmental determinants of immunologic variance in a healthy cohort population. In the current study we developed in vitro methods enabling standardized quantification of MI-cohort-derived primary fibroblasts responses. Our results show that in vitro human donor cohort fibroblast responses to stimulation by different MAMPs analogs allows to characterize individual donor immune-phenotype variability. The results provide proof-of-concept foundation to a new experimental framework for such studies. A bio-bank of primary fibroblast lines was generated from 323 out of 1,000 healthy individuals selected from the MI-study cohort. To study inter-donor variability of innate immune response in primary human dermal fibroblasts we chose to measure the TLR3 and TLR4 response pathways, both receptors being expressed and previously studied in fibroblasts. We established high-throughput automation compatible methods for standardized primary fibroblast cell activation, using purified MAMPS analogs, poly I:C and LPS that stimulate TLR3 and TLR4 pathways respectively. These results were in turn compared with a stimulation method using infection by HSV-1 virus. Our "Add-only" protocol minimizes high-throughput automation system variability facilitating whole process automation from cell plating through stimulation to recovery of cell supernatants, and fluorescent labeling. Images were acquired automatically by high-throughput acquisition on an automated high-content imaging microscope. Under these methodological conditions standardized image acquisition provided for quantification of cellular responses allowing biological variability to be measured with low system noise and high biological signal fidelity. Optimal for automated analysis of immuno-phenotype of primary human cell responses our method and experimental framework as reported here is highly compatible to high-throughput screening protocols like those necessary for chemo-genomic screening. In context of primary fibroblasts derived from donors enrolled to the MI-clinical-study our results open the way to assert the utility of studying immune-phenotype characteristics relevant to a human clinical cohort.

Tumor Milieu Controlled by RB Tumor Suppressor

The RB gene is one of the most frequently mutated genes in human cancers. Canonically, RB exerts its tumor suppressive activity through the regulation of the G1/S transition during cell cycle progression by modulating the activity of E2F transcription factors. However, aberration of the RB gene is most commonly detected in tumors when they gain more aggressive phenotypes, including metastatic activity or drug resistance, rather than accelerated proliferation. This implicates RB controls' malignant progression to a considerable extent in a cell cycle-independent manner. In this review, we highlight the multifaceted functions of the RB protein in controlling tumor lineage plasticity, metabolism, and the tumor microenvironment (TME), with a focus on the mechanism whereby RB controls the TME. In brief, RB inactivation in several types of cancer cells enhances production of pro-inflammatory cytokines, including CCL2, through upregulation of mitochondrial reactive oxygen species (ROS) production. These factors not only accelerate the growth of cancer cells in a cell-autonomous manner, but also stimulate non-malignant cells in the TME to generate a pro-tumorigenic niche in a non-cell-autonomous manner. Here, we discuss the biological and pathological significance of the non-cell-autonomous functions of RB and attempt to predict their potential clinical relevance to cancer immunotherapy.

Ephedrine enhances HIV-1 reactivation from latency through elevating tumor necrosis factor receptor II (TNFRII) expression

HIV-1 persists during antiretroviral therapy (ART) due to long-lived and proliferating latently-infected host cells, with the outcome being an incomplete cure. The latently-infected cells, or reservoir cells, are transcriptionally absent and invisible to the immune response. Elimination of latency is one strategy in activating virus production, making it visible to immune clearance. We previously showed that Ephedrae herba reactivated HIV-1 from latency. In this study, we used ephedrine, a major component of Ephedra herba, to reactivate HIV-1 from latency. The results showed that ephedrine enhances HIV-1 reactivation in the presence of TNFα. Combination treatment demonstrates a synergistic effect of HIV-1 reactivation compared to TNFα alone. Ephedrine treatment shows a higher TNFRII expression level, which is related to increased HIV-1 reactivation. However, the mechanism of ephedrine in HIV-1 reactivation is still unclear, and may be related to TNFRII receptor expression. Our results indicate that ephedrine enhances HIV-1 reactivation from latency in combination with TNFα treatment. This new reagent could be a promising latency reversal agent (LRA).

mSphere of Influence: Stromal Regulation of Epithelium Containing Viral Oncogenes

Jason Bodily works in the field of tumor virology. In this mSphere of Influence article, he reflects on how “Inactivation of Rb in stromal fibroblasts promotes epithelial cell invasion” by Adam Pickard et al. (EMBO J 31:3092–3103, 2012, https://doi.org/10.1038/emboj.2012.153) has impacted his work by making him think about the role of stromal cells in human papillomavirus infections.

Jason Bodily works in the field of tumor virology. In this mSphere of Influence article, he reflects on how “Inactivation of Rb in stromal fibroblasts promotes epithelial cell invasion” by Adam Pickard et al. (EMBO J 31:3092–3103, 2012, https://doi.org/10.1038/emboj.2012.153) has impacted his work by making him think about the role of stromal cells in human papillomavirus infections.

Simultaneous Transcriptional and Epigenomic Profiling from Specific Cell Types within Heterogeneous Tissues In Vivo

Epigenomic mechanisms direct distinct gene expression programs for different cell types. Various in vivo tissues have been subjected to epigenomic analysis; however, these studies have been limited by cellular heterogeneity, resulting in composite gene expression and epigenomic profiles. Here, we introduce "NuTRAP," a transgenic mouse that allows simultaneous isolation of cell-type-specific translating mRNA and chromatin from complex tissues. Using NuTRAP, we successfully characterize gene expression and epigenomic states of various adipocyte populations in vivo, revealing significant differences compared to either whole adipose tissue or in vitro adipocyte cell lines. We find that chromatin immunoprecipitation sequencing (ChIP-seq) using NuTRAP is highly efficient, scalable, and robust with even limited cell input. We further demonstrate the general utility of NuTRAP by analyzing hepatocyte-specific epigenomic states. The NuTRAP mouse is a resource that provides a powerful system for cell-type-specific gene expression and epigenomic profiling.

The Importance of Physiologically Relevant Cell Lines for Studying Virus-Host Interactions

Viruses interact intimately with the host cell at nearly every stage of replication, and the cell model that is chosen to study virus infection is critically important. Although primary cells reflect the phenotype of healthy cells in vivo better than cell lines, their limited lifespan makes experimental manipulation challenging. However, many tumor-derived and artificially immortalized cell lines have defects in induction of interferon-stimulated genes and other antiviral defenses. These defects can affect virus replication, especially when cells are infected at lower, more physiologically relevant, multiplicities of infection. Understanding the selective pressures and mechanisms underlying the loss of innate signaling pathways is helpful to choose immortalized cell lines without impaired antiviral defense. We describe the trials and tribulations we encountered while searching for an immortalized cell line with intact innate signaling, and how directed immortalization of primary cells avoids many of the pitfalls of spontaneous immortalization.

Emerging roles of p53 and other tumour-suppressor genes in immune regulation

Tumour-suppressor genes are indispensable for the maintenance of genomic integrity. Recently, several of these genes, including those encoding p53, PTEN, RB1 and ARF, have been implicated in immune responses and inflammatory diseases. In particular, the p53 tumour- suppressor pathway is involved in crucial aspects of tumour immunology and in homeostatic regulation of immune responses. Other studies have identified roles for p53 in various cellular processes, including metabolism and stem cell maintenance. Here, we discuss the emerging roles of p53 and other tumour-suppressor genes in tumour immunology, as well as in additional immunological settings, such as virus infection. This relatively unexplored area could yield important insights into the homeostatic control of immune cells in health and disease and facilitate the development of more effective immunotherapies. Consequently, tumour-suppressor genes are emerging as potential guardians of immune integrity.

The RB tumor suppressor at the intersection of proliferation and immunity: relevance to disease immune evasion and immunotherapy

The retinoblastoma tumor suppressor (RB) was the first identified tumor suppressor based on germline predisposition to the pediatric eye tumor. Since these early studies, it has become apparent that the functional inactivation of RB is a common event in nearly all human malignancy. A great deal of research has gone into understanding how the loss of RB promotes tumor etiology and progression. Since malignant tumors are characterized by aberrant cell division, much of this research has focused upon the ability of RB to regulate the cell cycle by repression of proliferation-related genes. However, it is progressively understood that RB is an important mediator of multiple functions. One area that is gaining progressive interest is the emerging role for RB in regulating diverse features of immune function. These findings suggest that RB is more than simply a regulator of cellular proliferation; it is at the crossroads of proliferation and the immune response. Here we review the data related to the functional roles of RB on the immune system, relevance to immune evasion, and potential significance to the response to immune-therapy.

Cell-Cycle Regulators and Cell Death in Immunity

Various cell death mechanisms are integral to host defense in both plants and mammals. Plant defense against biotrophic pathogens is associated with programmed cell death (PCD) of the infected cell. This effector-triggered PCD is partly analogous to pyroptosis, an inflammatory host cell death process that plays a crucial role in defense against microbial infections in mammals. Plant effector-triggered PCD also shares with mammalian apoptosis the involvement of cell-cycle regulators as signaling components. Here we explore the similarities between these different cell death programs as they relate to host defense and their relationship to the cell cycle.

Retinoblastoma tumor suppressor functions shared by stem cell and cancer cell strategies

Carcinogenic transformation of somatic cells resembles nuclear reprogramming toward the generation of pluripotent stem cells. These events share eternal escape from cellular senescence, continuous self-renewal in limited but certain population of cells, and refractoriness to terminal differentiation while maintaining the potential to differentiate into cells of one or multiple lineages. As represented by several oncogenes those appeared to be first keys to pluripotency, carcinogenesis and nuclear reprogramming seem to share a number of core mechanisms. The retinoblastoma tumor suppressor product retinoblastoma (RB) seems to be critically involved in both events in highly complicated manners. However, disentangling such complicated interactions has enabled us to better understand how stem cell strategies are shared by cancer cells. This review covers recent findings on RB functions related to stem cells and stem cell-like behaviors of cancer cells.

Oncolytic Viruses: Exploiting Cancer's Deal with the Devil

Tumor cells harbor tens to thousands of genetic and epigenetic alterations that disrupt cellular pathways, providing them with growth and survival advantages. However, these benefits come at a cost, with uncontrolled cell growth, defective apoptosis, sustained pathological angiogenesis, immune evasion, and a metastatic phenotype occurring at the expense of the antiviral response of the individual tumor cell. Oncolytic virotherapy is an emerging therapeutic strategy that uses replication-competent viruses to selectivity kill cancer cells by exploiting their impaired antiviral response. In this review, we outline our understanding of the alterations in signaling pathways that simultaneously contribute to the malignant phenotype and virus-mediated killing of cancer cells.

COMMD1/Murr1 reinforces HIV-1 latent infection through IκB-α stabilization

The transcription factor NF-κB is important for HIV-1 transcription initiation in primary HIV-1 infection and reactivation in latently HIV-1-infected cells. However, comparative analysis of the regulation and function of NF-κB in latently HIV-1-infected cells has not been done. Here we show that the expression of IκB-α, an endogenous inhibitor of NF-κB, is enhanced by latent HIV-1 infection via induction of the host-derived factor COMMD1/Murr1 in myeloid cells but not in lymphoid cells by using four sets of latently HIV-1-infected cells and the respective parental cells. IκB-α protein was stabilized by COMMD1, which attenuated NF-κB signaling during Toll-like receptor ligand and tumor necrosis factor alpha treatment and enhanced HIV-1 latency in latently HIV-1-infected cells. Activation of the phosphoinositol 3-kinase (PI3K)-JAK pathway is involved in COMMD1 induction in latently HIV-1-infected cells. Our findings indicate that COMMD1 induction is the NF-κB inhibition mechanism in latently HIV-1-infected cells that contributes to innate immune deficiency and reinforces HIV-1 latency. Thus, COMMD1 might be a double-edged sword that is beneficial in primary infection but not beneficial in latent infection when HIV-1 eradication is considered.

IMPORTANCE

HIV-1 latency is a major barrier to viral eradication in the era of combination antiretroviral therapy. In this study, we found that COMMD1/Murr1, previously identified as an HIV-1 restriction factor, inhibits the proteasomal degradation of IκB-α by increasing the interaction with IκB-α in latently HIV-1-infected myeloid cells. IκB-α protein was stabilized by COMMD1, which attenuated NF-κB signaling during the innate immune response and enhanced HIV-1 latency in latently HIV-1-infected cells. Activation of the PI3K-JAK pathway is involved in COMMD1 induction in latently HIV-1-infected cells. Thus, the host-derived factor COMMD1 is beneficial in suppressing primary infection but enhances latent infection, indicating that it may be a double-edged sword in HIV-1 eradication.

Retinoblastoma protein potentiates the innate immune response in hepatocytes: significance for hepatocellular carcinoma

Cancers mediated by viral etiology must exhibit deregulated cellular proliferation and evade immune recognition. The role of the retinoblastoma tumor suppressor (RB) pathway, which is lost at relatively high frequency in hepatocellular carcinoma (HCC), has recently been expanded to include the regulation of innate immune responsiveness. In this study we investigated the coordinate impact of RB-loss on cell cycle control and immune function in the liver. We found that RB depletion in hepatoma cells resulted in a compromised immunological response to multiple stimuli and reduced the potential of these cells to recruit myeloid cells. Viral-mediated liver-specific RB deletion in vivo led to the induction of genes associated with proliferation and cell cycle entry as well as the significant attenuation of genes associated with immune function, as evidenced by decreases in cytokine and chemokine expression, leukocyte recruitment, and hepatic inflammation. To determine if these changes in gene expression were instructive in human disease, we compared our liver-specific RB-loss gene signature to existing profiles of HCC and found that this signature was associated with disease progression and confers a worse prognosis.

CONCLUSION

Our data confirm that RB participates in the regulation of innate immunity in liver parenchymal cells both in vitro and in vivo and to our knowledge describes the first gene signature associated with HCC that includes both immunoregulatory and proliferative genes and that can also be attributed to the alteration of a single gene in vitro.

A functional polymorphism in the promoter region of TLR3 is associated with susceptibility to end-stage renal disease

BACKGROUND/AIMS

End-stage renal disease (ESRD) is simultaneously associated with immune activation, systemic inflammation and immune deficiency. Toll-like receptor 3 (TLR3), a receptor for viral double-stranded RNA, is involved in immune cell activation in renal diseases and may contribute to chronic inflammatory disease progression. To date, effects of TLR3 polymorphisms on ESRD remain unknown. Therefore, we determined the predictive value of TLR3 polymorphisms and further functionally studied ESRD.

METHODS

We performed a case-control association study and genotyped 616 ESRD patients and 813 healthy controls. Patients were genotyped for -7C/A, 1377C/T and 1234C/T polymorphisms of TLR3 using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The Haplotype association analysis was performed using the Haploview package. A luciferase reporter assay and real-time PCR were used to test the function of the -7C/A promoter polymorphism in TLR3 expression in human embryonic kidney 293 (HEK293) cells.

RESULTS

Genotype distributions of -7C/A and 1377C/T in TLR3 were significantly different in ESRD patients and healthy controls. The ATC haplotype of TLR3 was associated with a decreased risk of ESRD. We also found significant differences in TLR3 expression by dexamethasone treatment between various genotypes of -7C/A (p = 0.02). TLR3 transcriptional activity of the variant -7 C allele was higher than that of the -7 A allele after dexamethasone treatment.

CONCLUSION

RESULTS indicate that, in our population, the presence of the C allele of -7C/A in TLR3 increases the susceptibility to ESRD. In vitro studies demonstrated that -7C/A may be involved in ESRD development through transcriptional modulation of TLR3.

Comparative analysis of ER stress response into HIV protease inhibitors: lopinavir but not darunavir induces potent ER stress response via ROS/JNK pathway

HIV protease inhibitor (PI)-induced ER stress has been associated with adverse effects. Although it is a serious clinical problem for HIV/AIDS patients, comparative analyses of ER stress induction by clinically used PIs have rarely been done. Especially, there is no report on the differential ER stress response between lopinavir (LPV) and darunavir (DRV), although these PIs are the most clinically used PIs. We show here that LPV induces the most potent CHOP expression, ER stress marker, among the 9 Food and Drug Administration (FDA)-approved PIs in human peripheral blood mononuclear cells, several human epithelial cells, and mouse embryonic fibroblasts. LPV induced the most potent ROS production and JNK activation in 9 PIs. A comparison among the most clinically used PIs, ritonavir (RTV), LPV, and DRV, revealed that LPV potently and RTV moderately but not DRV induced ER stress via ROS-dependent JNK activation rather than proteasome inhibition. Finally, we analyzed ER stress induction in tissues of mice intraperitoneally injected with RTV, LPV, and DRV. RTV and LPV but not DRV showed ER stress induction in several mice tissues. In conclusion, we first identify LPV as the most potent ER stress inducing PI among 9 FDA-approved PIs in human cells, and although clinical verification is necessary, we show here that DRV has the advantage of less ROS and ER stress induction potential compared with LPV in vitro and in vivo.

Macrophages, inflammation, and tumor suppressors: ARF, a new player in the game

The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed.

Development of Therapeutic-Grade Small Interfering RNAs by Chemical Engineering

Recent successes in clinical trials have provided important proof of concept that small interfering RNAs (siRNAs) indeed constitute a new promising class of therapeutics. Although great efforts are still needed to ensure efficient means of delivery in vivo, the siRNA molecule itself has been successfully engineered by chemical modification to meet initial challenges regarding specificity, stability, and immunogenicity. To date, a great wealth of siRNA architectures and types of chemical modification are available for promoting safe siRNA-mediated gene silencing in vivo and, consequently, the choice of design and modification types can be challenging to individual experimenters. Here we review the literature and devise how to improve siRNA performance by structural design and specific chemical modification to ensure potent and specific gene silencing without unwarranted side-effects and hereby complement the ongoing efforts to improve cell targeting and delivery by other carrier molecules.