PDLIM2 restricts Th1 and Th17 differentiation and prevents autoimmune disease

Improving PD-1 blockade plus chemotherapy for complete remission of lung cancer by nanoPDLIM2

Immune checkpoint inhibitors (ICIs) and their combination with other therapies such as chemotherapy, fail in most cancer patients. We previously identified the PDZ-LIM domain-containing protein 2 (PDLIM2) as a bona fide tumor suppressor that is repressed in lung cancer to drive cancer and its chemo and immunotherapy resistance, suggesting a new target for lung cancer therapy improvement. In this study, human clinical samples and data were used to investigate PDLIM2 genetic and epigenetic changes in lung cancer. Using an endogenous mouse lung cancer model faithfully recapitulating refractory human lung cancer and a clinically feasible nano-delivery system, we investigated the therapeutic efficacy, action mechanism, and safety of systemically administrated PDLIM2 expression plasmids encapsulated in nanoparticles (nanoPDLIM2) and its combination with PD-1 antibody and chemotherapeutic drugs. Our analysis indicate that PDLIM2 repression in human lung cancer involves both genetic deletion and epigenetic alteration. NanoPDLIM2 showed low toxicity, high tumor specificity, antitumor activity, and greatly improved the efficacy of anti-PD-1 and chemotherapeutic drugs, with complete tumor remission in most mice and substantial tumor reduction in the remaining mice by their triple combination. Mechanistically, nanoPDLIM2 increased major histocompatibility complex class I (MHC-I) expression, suppressed multi-drug resistance 1 (MDR1) induction and survival genes and other tumor-related genes expression in tumor cells, and enhanced lymphocyte tumor infiltration, turning the cold tumors hot and sensitive to ICIs and rendering them vulnerable to chemotherapeutic drugs and activated tumor-infiltrating lymphocytes (TILs) including those unleashed by ICIs. These studies established a clinically applicable PDLIM2-based combination therapy with great efficacy for lung cancer and possibly other cold cancers.

NF-κB1 deficiency promotes macrophage-derived adrenal tumors but decreases neurofibromas in HTLV-I LTR-Tax transgenic mice

Human T-cell leukemia virus type I (HTLV-I) is an oncogenic virus whose infection can cause diverse diseases, most notably adult T-cell leukemia/lymphoma (ATL or ATLL), an aggressive and fatal malignancy of CD4 T cells. The oncogenic ability of HTLV-I is mostly attributed to the viral transcriptional transactivator Tax. Tax alone is sufficient to induce specific tumors in mice depending on the promotor used to drive Tax expression, thereby being used to understand HTLV-I tumorigenesis and model the tumor types developed in Tax transgenic mice. Tax exerts its oncogenic role predominantly by activating the cellular transcription factor NF-κB. Here, we report that genetic deletion of NF-κB1, the prototypic member of the NF-κB family, promotes adrenal medullary tumors but suppresses neurofibromas in mice with transgenic Tax driven by the HTLV-I Long Terminal Repeat (LTR) promoter. The adrenal tumors are derived from macrophages. Neoplastic macrophages also infiltrate the spleen and lymph nodes, causing splenomegaly and lymphadenopathy in mice. Nevertheless, the findings could be human relevant, because macrophages are important target cells of HTLV-I infection and serve as a virus reservoir in vivo. Moreover, the spleen, lymph nodes and adrenal glands are the most common sites of tumor cell infiltration in HTLV-I-infected patients. These data provide new mechanistic insights into the complex interaction between Tax and NF-κB, therefore improving our understanding of HTLV-I oncogenic pathogenesis. They also expand our knowledge and establish a new animal model of macrophage neoplasms and adrenal tumors.

Critical and distinct roles of cell type-specific NF-κB2 in lung cancer

Different from the well-studied canonical NF-κB member RelA, the role of the noncanonical NF-κB member NF-κB2 in solid tumors, and lung cancer in particular, is poorly understood. Here we report that in contrast to the tumor-promoting role of RelA, NF-κB2 intrinsic to lung epithelial and tumor cells had no marked effect on lung tumorigenesis and progression. On the other hand, NF-κB2 limited dendritic cell number and activation in the lung but protected lung macrophages and drove them to promote lung cancer through controlling activation of noncanonical and canonical NF-κB, respectively. NF-κB2 was also required for B cell maintenance and T cell activation. The antitumor activity of lymphocyte NF-κB2 was dominated by the protumor function of myeloid NF-κB2; thus, NF-κB2 has an overall tumor-promoting activity. These studies reveal a cell type-dependent role for NF-κB2 in lung cancer and help understand the complexity of NF-κB action and lung cancer pathogenesis for better design of NF-κB-targeted therapy against this deadliest cancer.

Improving PD-1 blockade plus chemotherapy for complete remission of lung cancer by nanoPDLIM2

Background

Immune checkpoint inhibitors (ICIs) and their combination with other therapies such as chemotherapy, fail in most cancer patients. We previously identified the PDZ-LIM domain-containing protein 2 (PDLIM2) as a bona fide tumor suppressor that is repressed in lung cancer to drive cancer and its chemo and immunotherapy resistance, suggesting a new target for lung cancer therapy improvement.

Methods

Human clinical samples and data were used to investigate PDLIM2 genetic and epigenetic changes in lung cancer. Using an endogenous mouse lung cancer model faithfully recapitulating refractory human lung cancer and a clinically feasible nano-delivery system, we investigated the therapeutic efficacy, action mechanism, and safety of systemically administrated PDLIM2 expression plasmids encapsulated in nanoparticles (nanoPDLIM2) and its combination with PD-1 antibody and chemotherapeutic drugs.

Results

PDLIM2 repression in human lung cancer involves both genetic deletion and epigenetic alteration. NanoPDLIM2 showed low toxicity, high tumor specificity, antitumor activity, and greatly improved the efficacy of anti-PD-1 and chemotherapeutic drugs, with complete tumor remission in most mice and substantial tumor reduction in the remaining mice by their triple combination. Mechanistically, nanoPDLIM2 increased major histocompatibility complex class I (MHC-I) expression, suppressed multi-drug resistance 1 (MDR1) induction and survival genes and other tumor-related genes expression in tumor cells, and enhanced lymphocyte tumor infiltration, turning the cold tumors hot and sensitive to ICIs and rendering them vulnerable to chemotherapeutic drugs and activated tumor-infiltrating lymphocytes (TILs) including those unleashed by ICIs.

Conclusions

These studies established a clinically applicable PDLIM2-based combination therapy with great efficacy for lung cancer and possibly other cold cancers.

Structural Investigations of Interactions between the Influenza a Virus NS1 and Host Cellular Proteins

The Influenza A virus is a continuous threat to public health that causes yearly epidemics with the ever-present threat of the virus becoming the next pandemic. Due to increasing levels of resistance, several of our previously used antivirals have been rendered useless. There is a strong need for new antivirals that are less likely to be susceptible to mutations. One strategy to achieve this goal is structure-based drug development. By understanding the minute details of protein structure, we can develop antivirals that target the most conserved, crucial regions to yield the highest chances of long-lasting success. One promising IAV target is the virulence protein non-structural protein 1 (NS1). NS1 contributes to pathogenicity through interactions with numerous host proteins, and many of the resulting complexes have been shown to be crucial for virulence. In this review, we cover the NS1-host protein complexes that have been structurally characterized to date. By bringing these structures together in one place, we aim to highlight the strength of this field for drug discovery along with the gaps that remain to be filled.

The unexpected versatility of ALP/Enigma family proteins

One of the most intriguing features of multicellular animals is their ability to move. On a cellular level, this is accomplished by the rearrangement and reorganization of the cytoskeleton, a dynamic network of filamentous proteins which provides stability and structure in a stationary context, but also facilitates directed movement by contracting. The ALP/Enigma family proteins are a diverse group of docking proteins found in numerous cellular milieus and facilitate these processes among others. In vertebrates, they are characterized by having a PDZ domain in combination with one or three LIM domains. The family is comprised of CLP-36 (PDLIM1), Mystique (PDLIM2), ALP (PDLIM3), RIL (PDLIM4), ENH (PDLIM5), ZASP (PDLIM6), and Enigma (PDLIM7). In this review, we will outline the evolution and function of their protein domains which confers their versatility. Additionally, we highlight their role in different cellular environments, focusing specifically on recent advances in muscle research using Drosophila as a model organism. Finally, we show the relevance of this protein family to human myopathies and the development of muscle-related diseases.

High Expression of PDLIM2 Predicts a Poor Prognosis in Prostate Cancer and Is Correlated with Epithelial-Mesenchymal Transition and Immune Cell Infiltration

Purpose

To elucidate the clinical and prognostic role of PDZ and LIM domain protein (PDLIM) genes and the association to epithelial-mesenchymal transition (EMT) and immune cell infiltration in patients with prostate cancer (PRAD).

Methods

The data of RNA-seq, DNA methylation, and clinical features of PRAD patients were collected from The Cancer Genome Atlas (TCGA) database to define the prognostic value of PDLIM gene expression and the association with EMT and immune cell infiltration. A tissue microarray including 134 radical prostatectomy specimens was served as validation by immunohistochemistry (IHC) staining analysis.

Results

The mRNA levels of PDLIM1/2/3/4/6/7 were significantly downregulated, while PDLIM5 was upregulated in PRAD (P < 0.05). High expression of PDLIM2 mRNA suggests poor progression free interval in PRAD patients. DNA methylation of PDLIM2 was correlated with its mRNA expression level, and that the cg22973076 methylation site in PDLIM2 was associated with shorter PFI (P < 0.05) in PRAD. Single-sample gene-set enrichment and gene functional enrichment results showed that PDLIM2 was correlated with EMT and immune processes. Spearman's test showed a significant correlation with six reported EMT signatures and several EMT signature-related genes. Tumor microenvironment analysis revealed that the PDLIM2 mRNA expression was positively correlated with the immune score, stromal score, and various tumor infiltrating immune cells. Additionally, the results showed that patients in the high-PDLIM2 mRNA expression group may be more sensitive to immune checkpoint blockade therapy. Finally, IHC analysis further implicated the protein level of PDLIM2 was upregulated in PRAD and acts as a novel potential biomarker in predicting tumor progression.

Conclusion

Our study suggests that PDLIM family genes might be significantly correlated with oncogenesis and the progression of PRAD. PDLIM2 correlated with EMT and immune cell infiltration by acting as an oncogene in PRAD, which may serve as a potential prognostic biomarker for PRAD patients.

The effects of post-translational modifications on Th17/Treg cell differentiation

Regulatory T (Treg) cells and Th17 cells are subsets of CD4⁺ T cells which play an essential role in immune homeostasis and infection. Dysregulation of the Th17/Treg cell balance was shown to be implicated in the development and progression of several disorders such as autoimmune disease, inflammatory disease, and cancer. Multiple factors, including T cell receptor (TCR) signals, cytokines, metabolic and epigenetic regulators can influence the differentiation of Th17 and Treg cells and affect their balance. Accumulating evidence indicates that the activity of key molecules such as forkhead box P3 (Foxp3), the retinoic acid-related orphan receptor gamma t (RORγt), and signal transducer and activator of transcription (STAT)s are modulated by the number of post-translational modifications (PTMs) such as phosphorylation, methylation, nitrosylation, acetylation, glycosylation, lipidation, ubiquitination, and SUMOylation. PTMs might affect the protein folding efficiency and protein conformational stability, and consequently determine protein structure, localization, and function. Here, we review the recent progress in our understanding of how PTMs modify the key molecules involved in the Th17/Treg cell differentiation, regulate the Th17/Treg balance, and initiate autoimmune diseases caused by dysregulation of the Th17/Treg balance. A better understanding of Th17/Treg regulation may help to develop novel potential therapeutics to treat immune-related diseases.

Systematic evaluation of the prognostic and immunological role of PDLIM2 across 33 cancer types

The protein PDLIM2 regulates the stability of various transcription factors and is required for polarized cell migration. However, the clinical relevance and immune infiltration of PDLIM2 in cancer are not well-understood. We utilized The Cancer Genome Atlas and Genotype-Tissue Expression database to characterize alterations in PDLIM2 in pan-cancer. TIMER was used to explore PDLIM2 expression and immune infiltration levels. We assessed the correlation between PDLIM2 expression and immune-associated gene expression, immune score, tumor mutation burden, and DNA microsatellite instability. PDLIM2 significantly affected the prognosis of various cancers. Increased expression of PDLIM2 was significantly correlated with the tumor grade in seven types of tumors. The expression level of PDLIM2 was positively correlated with immune infiltrates, including B cells, CD8+ T cells, CD4+ T cells, neutrophils, macrophages, and dendritic cells in bladder urothelial, kidney renal papillary cell, and colon adenocarcinoma. High expression levels of PDLIM2 tended to be associated with higher immune and stromal scores. PDLIM2 expression was associated with the tumor mutation burden in 12 cancer types and microsatellite instability in 5 cancer types. PDLIM2 levels were strongly correlated with diverse immune-related genes. PDLIM2 can act as a prognostic-related therapeutic target and is correlated with immune infiltrates in pan-cancer.

PDLIM2: Signaling pathways and functions in cancer suppression and host immunity

PDZ and LIM domains-containing proteins play pivotal functions in cell cytoskeleton organization, cell polarization and differentiation. As a key member of the family, PDLIM2 regulates stability and activity of transcription factors such as NF-κB, STATs and β-catenin, and thus exert it functions in inflammation, immunity, and cancer. PDLIM2 functions as a tumor suppressor in multiple tissues and it is often genetically mutated or epigenetically silenced in human cancers derived from lung, breast, ovarian and other histologies. However, in certain types of cancers, PDLIM2 may promote cancer cell proliferation and metastases. Therefore, PDLIM2 is added to a long list of genes that can function as tumor suppressor or oncogenic protein. During tumorigenesis induced by oncogenic viruses, PDLIM2 is a key target. Through promotion of NF-κB/RelA and STAT3 degradation, PDLIM2 enhances expression of proteins involved in antigen presentation and promotes T-cell activation while repressing multidrug resistance genes, thereby rendering mutated cells susceptible to immune surveillance and cytotoxicity mediated by immune cells and chemotherapeutic drugs. Intriguingly, PDLIM2 in alveolar macrophages (AMs) plays key roles in monitoring lung tumorigenesis, as its selective genetic deletion leads to constitutive activation of STAT3, driving monocyte differentiation to AMs with pro-tumorigenic polarization and activation. PDLIM2 has also been explored as a therapeutic target for cancer therapy. At the end of this review, we provide perspectives on this important molecule and discuss the future directions of both basic and translational studies.

Alveolar Macrophages Inherently Express Programmed Death-1 Ligand 1 for Optimal Protective Immunity and Tolerance

Macrophages play a central role in lung physiology and pathology. In this study, we show in mice that alveolar macrophages (AMs), unlike other macrophage types (interstitial, peritoneal, and splenic macrophages), constitutively express programmed death-1 ligand 1 (PD-L1), thereby possessing a superior phagocytic ability and the capacity to repress CTLs by cis- and trans-interacting with CD80 and programmed death-1 (PD-1), respectively. This extraordinary ability of AMs assures optimal protective immunity and tolerance within the lung. These findings uncover a unique characteristic of AMs and an innate immune function of PD-L1 and CD80 and therefore help in the understanding of lung physiology, diseases, and PD-L1/PD-1-based immunotherapy.

Dual but not single PD-1 or TIM-3 blockade enhances oncolytic virotherapy in refractory lung cancer

Background

Programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade therapy fails in the majority of patients with cancer. Oncolytic viruses represent a new class of therapeutic agents, yet the therapeutic efficacy is still disappointing. Moreover, intratumoral injection of viruses is the main approach and preclinical studies mainly employ syngeneic or xenograft models.

Methods

Use an endogenous mouse lung cancer model that faithfully recapitulates human lung cancer, and various in vivo, ex vivo and in vitro assays, to investigate the efficacy, mechanism of action and resistance of systemically administered oncolytic vaccinia virus (oVV), immunotherapy and their combination, to find an effective therapy for refractory lung cancer.

Results

Resembling human lung cancers, the majority of which are largely resistant to PD-1/PD-L1 blockade and with decreased PD-L1 expression and T-cell activation by our analysis, urethane-induced endogenous lung tumors in mice show reduced PD-L1 expression, low tumor-infiltrating lymphocytes and innate resistance to PD-1/PD-L1 blockade. Intravenous administration of oVV has efficacy and synergizes with simultaneous but not single blockade of PD-1 and T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) in this cancer model. Besides direct tumor cell killing, oVV induces T-cell lung recruitment, tumor infiltration, along with expression of PD-1 and TIM-3 on T cells and PD-1 and TIM-3 ligands on tumor cells and tumor-associated immune cells. Blockade of PD-1 or TIM-3 also causes their mutual induction on T cells.

Conclusions

While systemic administration of oVV shows efficacy in lung cancer by killing tumor cells directly and recruiting and activating T cells for indirect tumor killing, its induction of PD-1 and TIM-3 on T cells and PD-1 and TIM-3 ligands on tumors and tumor-associated immune cells as well as mutual induction of PD-1 or TIM-3 on T cells by their blockade restricts the efficacy of oVV or its combination with single PD-1 or TIM-3 blockade. The triple combination therapy is more effective for refractory lung cancer, and possibly other cold cancers as well.

PDLIM2 repression by ROS in alveolar macrophages promotes lung tumorigenesis

One of the most fundamental and challenging questions in the field of cancer is how immunity is transformed from tumor immunosurveillance to tumor-promoting inflammation. Here, we identified the tumor suppressor PDZ-LIM domain–containing protein 2 (PDLIM2) as a checkpoint of alveolar macrophages (AMs) important for lung tumor suppression. During lung tumorigenesis, PDLIM2 expression in AMs is downregulated by ROS-activated transcription repressor BTB and CNC homology 1 (BACH1). PDLIM2 downregulation leads to constitutive activation of the transcription factor STAT3, driving AM protumorigenic polarization/activation and differentiation from monocytes attracted from the circulation to suppress cytotoxic T lymphocytes and promote lung cancer. PDLIM2 downregulation also decreases AM phagocytosis. These findings establish ROS/BACH1/PDLIM2/STAT3 as a signaling pathway driving AMs for lung tumor promotion.

PDLIM2 prevents the malignant phenotype of hepatocellular carcinoma cells by negatively regulating β-catenin

Hepatocellular carcinoma (HCC) is one of the most common malignancies and leading causes of cancer-related deaths globally. Despite significant advances in therapy, the molecular mechanisms underlying HCC development and progression remain unclear. Here, we aimed to explore the potential role of PDLIM2 in the development and epithelial-mesenchymal transition (EMT) of HCC via a possible modulation of β-catenin. We first confirmed that PDLIM2 was downregulated in HCC tissues and cells and found lower PDLIM2 expression was associated with worse prognosis in HCC patients. Loss- and gain- of function experiments were performed to evaluate the roles of PDLIM2 and β-catenin in HCC cell proliferation, migration, invasion, EMT, and colony formation. EMT was determined based on the levels of E-cadherin, zonula occludens-1, N-cadherin, and vimentin expression. In vivo, the roles of PDLIM2 and β-catenin in HCC were investigated by using a nude mouse xenograft model. It should be noted that PDLIM2 led to the inhibition of β-catenin activity and its downstream gene expression. Importantly, ectopic PDLIM2 expression inhibited the proliferation, migration, invasion, and EMT of HCC cells by reducing β-catenin expression both in vitro and in vivo, thereby suppressing the occurrence and progression of HCC. Taken together, our results demonstrated that overexpressed PDLIM2 exerts a tumor-suppressive role in HCC by regulating β-catenin. This study suggests that the PDLIM2 may be a promising target for the treatment of HCC.

PDLIM2 protects articular chondrocytes from lipopolysaccharide-induced apoptosis, degeneration and inflammatory injury through down-regulation of nuclear factor (NF)-κB signaling

Excessive inflammatory response-induced apoptosis and the degeneration of articular chondrocytes contribute to the development and progression of osteoarthritis. PDZ and LIM domain containing protein 2 (PDLIM2) has emerged as one of the pivotal regulators in orchestrating an inflammatory response through regulating the activity of transcription factor nuclear factor (NF)-κB. However, whether PDLIM2 participates in the articular chondrocyte-associated inflammatory response in osteoarthritis remains unknown. In the current study, we aimed to explore the biological function of PDLIM2 in lipopolysaccharide (LPS)-stimulated articular chondrocytes, an in vitro model of osteoarthritis. Herein, we found that PDLIM2 expression was significantly down-regulated in chondrocytes in response to LPS exposure. Functional experiments revealed that PDLIM2 overexpression increased the viability and decreased the apoptosis of chondrocytes following LPS treatment. Moreover, PDLIM2 overexpression attenuated LPS-induced degeneration of chondrocytes via the down-regulation of matrix metalloproteinase (MMP)-3 and MMP-13 and the up-regulation of COL2A1 and ACAN. In addition, the overexpression of PDLIM2 decreased LPS-induced production of interleukin (IL)-1β, IL-6 and TNF-α. In contrast, depletion of PDLIM2 exhibited the opposite effect. Mechanism research elucidated that PDLIM2 repressed the activation of NF-κB signaling associated with the down-regulation of NF-κB p65 protein expression. PDLIM2 depletion-exacerbated LPS-induced injury was significantly reversed by NF-κB inhibition. Taken together, these results demonstrate that PDLIM2 overexpression attenuates LPS-induced injury of articular chondrocytes through the inactivation of NF-κB signaling.

PDLIM2 acts as a cancer suppressor gene in non-small cell lung cancer via the down regulation of NF-κB signaling

PDZ and LIM domain containing protein 2 (PDLIM2) has been identified as a vital tumor-associated gene that is aberrantly expressed in various types of tumors. Yet, the involvement of PDLIM2 in non-small cell lung cancer (NSCLC) is currently undetermined. The design of the current study was to evaluate whether PDLIM2 plays a role in NSCLC. We found that PDLIM2 expression was commonly decreased in NSCLC tissues. Moreover, low expression of PDLIM2 was also detected in NSCLC cell lines and demethylation treatment restored PDLIM2 expression. The re-expression of PDLIM2 impeded the proliferative, colony-forming, and invasive capabilities of NCLCL cells. In contrast, depletion of PDLIM2 markedly enhanced the malignant behaviors of NSCLC cells. Notably, PDLIM2 overexpression downregulated the expression of nuclear factor (NF)-κB p65 subunit and repressed NF-κB transcription reporter activity in NSCLC cells. The overexpression of p65 significantly reversed PDLIM2-mediated antitumor effects in NSCLC cells. Additionally, the Xenograft tumor formation assay revealed that the overexpression of PDLIM2 markedly restricted the tumor growth of NSCLC in vivo. Overall, our study confirms that PDLIM2 acts as a tumor-inhibitor in NSCLC through the inactivation of NF-κB, suggesting PDLIM2 as a candidate therapeutic target for NSCLC.

Causative role of PDLIM2 epigenetic repression in lung cancer and therapeutic resistance

Most cancers are resistant to anti-PD-1/PD-L1 and chemotherapy. Herein we identify PDLIM2 as a tumor suppressor particularly important for lung cancer therapeutic responses. While PDLIM2 is epigenetically repressed in human lung cancer, associating with therapeutic resistance and poor prognosis, its global or lung epithelial-specific deletion in mice causes increased lung cancer development, chemoresistance, and complete resistance to anti-PD-1 and epigenetic drugs. PDLIM2 epigenetic restoration or ectopic expression shows antitumor activity, and synergizes with anti-PD-1, notably, with chemotherapy for complete remission of most lung cancers. Mechanistically, through repressing NF-κB/RelA and STAT3, PDLIM2 increases expression of genes involved in antigen presentation and T-cell activation while repressing multidrug resistance genes and cancer-related genes, thereby rendering cancer cells vulnerable to immune attacks and therapies. We identify PDLIM2-independent PD-L1 induction by chemotherapeutic and epigenetic drugs as another mechanism for their synergy with anti-PD-1. These findings establish a rationale to use combination therapies for cancer treatment.

PDLIM2 is repressed epigenetically in lung cancers, which are frequently resistant to anti-PD-1/PD-L1 and chemotherapy. Here, the authors describe the mechanism through which epigenetic restoration of PDLIM2 synergises with anti-PD-1 and chemotherapy in lung cancers.

Viral targeting of PDZ polarity proteins in the immune system as a potential evasion mechanism

PDZ proteins are highly conserved through evolution; the principal function of this large family of proteins is to assemble protein complexes that are involved in many cellular processes, such as cell-cell junctions, cell polarity, recycling, or trafficking. Many PDZ proteins that have been identified as targets of viral pathogens by promoting viral replication and spread are also involved in epithelial cell polarity. Here, we briefly review the PDZ polarity proteins in cells of the immune system to subsequently focus on our hypothesis that the viral PDZ-dependent targeting of PDZ polarity proteins in these cells may alter the cellular fitness of the host to favor that of the virus; we further hypothesize that this modification of the cellular fitness landscape occurs as a common and widespread mechanism for immune evasion by viruses and possibly other pathogens.-Gutiérrez-González, L. H., Santos-Mendoza, T. Viral targeting of PDZ polarity proteins in the immune system as a potential evasion mechanism.

Contribution of STAT3 and RAD23B in Primary Sézary Cells to Histone Deacetylase Inhibitor FK228 Resistance

FK228 (romidepsin) and suberoylanilide hydroxamic acid (vorinostat) are histone deacetylase inhibitors (HDACi) approved by the US Food and Drug Administration for cutaneous T-cell lymphoma (CTCL), including the leukemic subtype Sézary syndrome. This study investigates RAD23B and STAT3 gene perturbations in a large cohort of primary Sézary cells and the effect of FK228 treatment on tyrosine phosphorylation of STAT3 (pYSTAT3) and RAD23B expression. We report RAD23B copy number variation in 10% (12/119, P ≤ 0.01) of SS patients, associated with reduced mRNA expression (P = 0.04). RAD23B knockdown in a CTCL cell line led to a reduction in FK228-induced apoptosis. Histone deacetylase inhibitor treatment significantly reduced pYSTAT3 in primary Sézary cells and was partially mediated by RAD23B. A distinct pattern of RAD23B-pYSTAT3 co-expression in primary Sézary cells was detected. Critically, Sézary cells harboring the common STAT3 Y640F variant were less sensitive to FK228-induced apoptosis and exogenous expression of STAT3 Y640F, and D661Y conferred partial resistance to STAT3 transcriptional inhibition by FK228 (P ≤ 0.0024). These findings suggest that RAD23B and STAT3 gene perturbations could reduce sensitivity to histone deacetylase inhibitors in SS patients.

Posttranscriptional regulation of T helper cell fate decisions

Hoefig and Heissmeyer review how microRNAs, long noncoding RNAs, RNA-binding proteins, and ubiquitin-modifying enzymes regulate T helper cell differentiation downstream of transcription.

T helper cell subsets orchestrate context- and pathogen-specific responses of the immune system. They mostly do so by secreting specific cytokines that attract or induce activation and differentiation of other immune or nonimmune cells. The differentiation of T helper 1 (Th1), Th2, T follicular helper, Th17, and induced regulatory T cell subsets from naive T cells depends on the activation of intracellular signal transduction cascades. These cascades originate from T cell receptor and costimulatory receptor engagement and also receive critical input from cytokine receptors that sample the cytokine milieu within secondary lymphoid organs. Signal transduction then leads to the expression of subset-specifying transcription factors that, in concert with other transcription factors, up-regulate downstream signature genes. Although regulation of transcription is important, recent research has shown that posttranscriptional and posttranslational regulation can critically shape or even determine the outcome of Th cell differentiation. In this review, we describe how specific microRNAs, long noncoding RNAs, RNA-binding proteins, and ubiquitin-modifying enzymes regulate their targets to skew cell fate decisions.

NF-κB RelA renders tumor-associated macrophages resistant to and capable of directly suppressing CD8+ T cells for tumor promotion

Activation of the inflammatory transcription factor NF-κB in tumor-associated macrophages (TAMs) is assumed to contribute to tumor promotion. However, whether and how NF-κB drives the antitumor macrophages to become pro-tumorigenic have not been determined in any cancer type yet. Similarly, how TAMs repress CD8⁺ cytotoxic T lymphocytes (CTLs) remains largely unknown, although their importance in regulatory T (Treg) cell regulation and tumor promotion has been well appreciated. Here, using an endogenous lung cancer model we uncover a direct crosstalk between TAMs and CTLs. TAMs suppress CTLs through the T-cell inhibitory molecule B7x (B7-H4/B7S1) in a cell-cell contact manner, whereas CTLs kill TAMs in a tumor antigen-specific manner. Remarkably, TAMs secrete the known T-cell suppressive cytokine interleukin-10 (IL-10) to activate, but not to repress, CTLs. Notably, one major role of cell-intrinsic NF-κB RelA is to drive TAMs to suppress CTLs for tumor promotion. It induces B7x expression in TAMs directly, and restricts IL-10 expression indirectly by repressing expression of the NF-κB cofactor Bcl3 and subsequent Bcl3/NF-κB1-mediated transcription of IL-10. It also renders TAMs resistant to CTLs by up-regulating anti-apoptotic genes. These studies help understand how immunity is shaped in lung tumorigenesis, and suggest a RelA-targeted immunotherapy for this deadliest cancer.

Exome and transcriptome sequencing identifies loss of PDLIM2 in metastatic colorectal cancers

Background

Understanding the genomic determinants associated with metastasis in colorectal cancers (CRCs) provides crucial clues for improving patient care.

Patients and methods

In this study, we performed whole-exome sequencing as well as RNA sequencing analyses on five pairs of primary and liver metastasized samples from CRC patients together with blood/normal control samples for each pair.

Results

We identified genomic deletions in the region of 8p21-23 (q value <0.01) from analysis of recurrent regions with copy number variations in both primary and matched metastatic lesions. Consistent with this result, we found significantly decreased expression levels of all 12 genes (ADAMDEC1, C8orf80, CLDN23, EPHX2, GFRA2, NEFL, NEFM, PDLIM2, PTK2B, SCARA5, SLC18A1 and STMN4) located within this region (adjusted P<0.01). Notably, the mRNA levels of PDLIM2, a key regulator of well-known cancer-associated genes including the proto-oncogene c-MYC, an early response gene IER3, and regulators of apoptosis such as BCL2, FAS, and FASLG, were highly downregulated in tumors compared to normal tissues.

Conclusion

Taken together, our findings uncovered various genomic alterations potentially leading to metastasis in CRC and provide important insights into the development of potential therapeutic targets for preventing metastatic progression of CRC.

Myeloid STAT3 Promotes Lung Tumorigenesis by Transforming Tumor Immunosurveillance into Tumor-Promoting Inflammation

One of the most fundamental and challenging questions in the cancer field is how immunity in patients with cancer is transformed from tumor immunosurveillance to tumor-promoting inflammation. Here, we identify the transcription factor STAT3 as the culprit responsible for this pathogenic event in lung cancer development. We found that antitumor type 1 CD4⁺ T-helper (Th1) cells and CD8⁺ T cells were directly counter balanced in lung cancer development with tumor-promoting myeloid-derived suppressor cells (MDSCs) and suppressive macrophages, and that activation of STAT3 in MDSCs and macrophages promoted tumorigenesis through pulmonary recruitment and increased resistance of suppressive cells to CD8⁺ T cells, enhancement of cytotoxicity toward CD4⁺ and CD8⁺ T cells, induction of regulatory T cell (Treg), inhibition of dendritic cells (DC), and polarization of macrophages toward the M2 phenotype. The deletion of myeloid STAT3 boosted antitumor immunity and suppressed lung tumorigenesis. These findings increase our understanding of immune programming in lung tumorigenesis and provide a mechanistic basis for developing STAT3-based immunotherapy against this and other solid tumors. Cancer Immunol Res; 5(3); 257-68. ©2017 AACR.

Ubiquitin Ligases and Deubiquitinating Enzymes in CD4+ T Cell Effector Fate Choice and Function

The human body is exposed to potentially pathogenic microorganisms at barrier sites such as the skin, lungs, and gastrointestinal tract. To mount an effective response against these pathogens, the immune system must recruit the right cells with effector responses that are appropriate for the task at hand. Several types of CD4(+) T cells can be recruited, including Th cells (Th1, Th2, and Th17), T follicular helper cells, and regulatory T cells. These cells help to maintain normal immune homeostasis in the face of constantly changing microbes in the environment. Because these cells differentiate from a common progenitor, the composition of their intracellular milieu of proteins changes to appropriately guide their effector function. One underappreciated process that impacts the levels and functions of effector fate-determining factors is ubiquitylation. This review details our current understanding of how ubiquitylation regulates CD4(+) T cell effector identity and function.

NF-κB1 p105 suppresses lung tumorigenesis through the Tpl2 kinase but independently of its NF-κB function

NF-κB is generally believed to be pro-tumorigenic. Here, we report a tumor-suppressive function for NF-κB1, the prototypical member of NF-κB. While NF-κB1 down-regulation is associated with high lung cancer risk in humans and poor patient survival, NF-κB1 deficient mice are more vulnerable to lung tumorigenesis induced by the smoke carcinogen, urethane. Notably, the tumor suppressive function of NF-κB1 is independent of its classical role as an NF-κB factor, but instead through stabilization of the Tpl2 kinase. NF-κB1 deficient tumors exhibit “normal” NF-κB activity, but a decreased protein level of Tpl2. Reconstitution of Tpl2 or the NF-κB1 p105, but not p50 (the processed product of p105), inhibits the tumorigenicity of NF-κB1 deficient lung tumor cells. Remarkably, Tpl2 knockout mice resemble NF-κB1 knockouts in urethane-induced lung tumorigenesis. Mechanistic studies indicate that p105/Tpl2 signaling is required for suppressing urethane-induced lung damage and inflammation, and activating mutations of the K-Ras oncogene. These studies reveal an unexpected, NF-κB-independent but Tpl2-depenednt role of NF-κB1 in lung tumor suppression. These studies also reveal a previously unexplored role of p105/Tpl2 signaling in lung homeostasis.

Oncovirus Kaposi sarcoma herpesvirus (KSHV) represses tumor suppressor PDLIM2 to persistently activate nuclear factor κB (NF-κB) and STAT3 transcription factors for tumorigenesis and tumor maintenance

Kaposi sarcoma herpesvirus (KSHV) is the most common cause of malignancies among AIDS patients. However, how KSHV induces tumorigenesis remains largely unknown. Here, we demonstrate that one important mechanism underlying the tumorigenesis of KSHV is through transcriptional repression of the tumor suppressor gene PDZ-LIM domain-containing protein 2 (PDLIM2). PDLIM2 expression is repressed in KSHV-transformed human umbilical vascular endothelial cells as well as in KSHV-associated cancer cell lines and primary tumors. Importantly, PDLIM2 repression is essential for KSHV-induced persistent activation of nuclear factor κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) and subsequent tumorigenesis and tumor maintenance. Our mechanistic studies indicate that PDLIM2 repression by KSHV involves DNA methylation. Notably, the epigenetic repression of PDLIM2 can be reversed by 5-aza-2-deoxycytidine and vitamin D to suppress KSHV-associated cancer cell growth. These studies not only improve our understanding of KSHV pathogenesis but also provide immediate therapeutic strategies for KSHV-mediated cancers, particularly those associated with AIDS.

Resident bacteria-stimulated IL-10-secreting B cells ameliorate T cell-mediated colitis by inducing Tr-1 cells that require IL-27-signaling

BACKGROUND & AIMS

Regulatory roles of IL-10-producing B cells in colitis are not fully understood. The aim of this study is to explore the molecular mechanisms by which these cells modulate mucosal homeostasis.

METHODS

CD4⁺ T cells from WT, Il10^-/- or Il27ra^-/- mice were co-transferred with B cells from specific pathogen-free (SPF) or germ-free (GF) WT or Il10^-/- mice into Rag2^-/-Il10^-/- (DKO) mice and the severity of colitis and intestinal regulatory T cell populations were characterized. In vitro, WT or Il10^-/- B cells were co-cultured with unfractionated, naïve or regulatory T cells plus Il10^-/- antigen-presenting cells and stimulated with cecal bacterial lysate (CBL) with or without IL-27 or anti-IL-10R blockade. Gene expressions, cytokines in the supernatant and cell populations were assessed.

RESULTS

WT but not Il10^-/- B cells attenuate Th1/Th17-mediated colitis in DKO mice that also received WT but not Il10^-/- T cells. In vitro, CBL-stimulated WT B cells secrete abundant IL-10 and suppress IFNγ and IL-17a-production by T cells without requiring cell contact. Although both WT and Il10^-/- B cells induce Foxp3⁺CD4⁺ Tregs, only WT B cells induce IL-10-producing (Foxp3-negative) T regulatory-1 (Tr-1) cells both in vivo and in vitro. However, IL-10-producing B cells did not attenuate colitis or induce Tr-1 cells in the absence of T cell IL-27-signaling in vivo. WT B cell-dependent Tr-1 induction and concomitant decreased IFNγ-secretion were also mediated by T-cell IL-27-signaling in vitro.

CONCLUSIONS

IL-10-secreting B cells activated by physiologically-relevant bacteria ameliorate T cell-mediated colitis and contribute to intestinal homeostasis by suppressing effector T cells and inducing Tr-1 cells via IL-27-signaling on T cells.

Differential roles of STAT3 in the initiation and growth of lung cancer

Signal transducer and activator of transcription 3 (STAT3) is linked to multiple cancers, including pulmonary adenocarcinoma. However, the role of STAT3 in lung cancer pathogenesis has not been determined. Using lung epithelial-specific inducible knockout strategies, we demonstrate that STAT3 has contrasting roles in the initiation and growth of both chemically and genetically induced lung cancers. Selective deletion of lung epithelial STAT3 in mice before cancer induction by the smoke carcinogen, urethane, resulted in increased lung tissue damage and inflammation, K-Ras oncogenic mutations and tumorigenesis. Deletion of lung epithelial STAT3 after establishment of lung cancer inhibited cancer cell proliferation. Simultaneous deletion of STAT3 and expression of oncogenic K-Ras in mouse lung elevated pulmonary injury, inflammation and tumorigenesis, but reduced tumor growth. These studies indicate that STAT3 prevents lung cancer initiation by maintaining pulmonary homeostasis under oncogenic stress, whereas it facilitates lung cancer progression by promoting cancer cell growth. These studies also provide a mechanistic basis for targeting STAT3 to lung cancer therapy.

PDLIM2 regulates transcription factor activity in epithelial-to-mesenchymal transition via the COP9 signalosome

PDLIM2 integrates cytoskeletal signaling with gene expression to enable reversible differentiation of epithelial cancer cells. PDLIM2 associates with the COP9 signalosome and controls its nuclear translocation and the stability of key transcription factors necessary for either a mesenchymal or an epithelial phenotype.

Epithelial cell differentiation and polarized migration associated with epithelial-to-mesenchymal transition (EMT) in cancer requires integration of gene expression with cytoskeletal dynamics. Here we show that the PDZ-LIM domain protein PDLIM2 (Mystique/SLIM), a known cytoskeletal protein and promoter of nuclear nuclear factor κB (NFκB) and signal transducer and activator of transcription (STAT) degradation, regulates transcription factor activity and gene expression through the COP9 signalosome (CSN). Although repressed in certain cancers, PDLIM2 is highly expressed in invasive cancer cells. Here we show that PDLIM2 suppression causes loss of directional migration, inability to polarize the cytoskeleton, and reversal of the EMT phenotype. This is accompanied by altered activity of several transcription factor families, including β-catenin, Ap-1, NFκB, interferon regulatory factors, STATs, JUN, and p53. We also show that PDLIM2 associates with CSN5, and cells with suppressed PDLIM2 exhibit reduced nuclear accumulation and deneddylation activity of the CSN toward the cullin 1 and cullin 3 subunits of cullin-RING ubiquitin ligases. Thus PDLIM2 integrates cytoskeleton signaling with gene expression in epithelial differentiation by controlling the stability of key transcription factors and CSN activity.

The 2012 Ming K Jeang award for excellence in cell & bioscience

Three research groups led by Dr. Lixin Feng of Shanghai JiaoTong University School of Medicine, Shanghai, China, Dr. Walter Wahli of University of Lausanne, Lausanne, Switzerland, and Dr. Gutian Xiao of University of Pittsburgh Cancer Institute, Pittsburgh, USA, won the 2012 Ming K Jeang Award for Excellence in Cell & Bioscience.

Regulation of nuclear factor-κB in autoimmunity

Nuclear factor (NF)-κB transcription factors are pivotal regulators of innate and adaptive immune responses, and perturbations of NF-κB signaling contribute to the pathogenesis of immunological disorders. NF-κB is a well-known proinflammatory mediator, and its deregulated activation is associated with the chronic inflammation of autoimmune diseases. Paradoxically, NF-κB plays a crucial role in the establishment of immune tolerance, including both central tolerance and the peripheral function of regulatory T (Treg) cells. Thus, defective or deregulated activation of NF-κB may contribute to autoimmunity and inflammation, highlighting the importance of tightly controlled NF-κB signaling. This review focuses on recent progress regarding NF-κB regulation and its association with autoimmunity.

Decreased signal transducers and activators of transcription (STAT) protein expression in lymphatic organs during EAE development in mice

Experimental autoimmune encephalomyelitis (EAE) is mediated by myelin-specific CD4+ T cells secreting Th1 and/or Th17 cytokines. Signal transducer and activator of transcription (STAT) family proteins have essential roles in transmitting Th1 and/or Th17 cytokine-mediated signals. However, most studies demonstrating the importance of the STAT signaling system in EAE have focused on distinct members of this family, often looking at their role specifically in the central nervous system, or in vitro. There is limited information available regarding the temporal and spatial expression patterns of each STAT protein and interplay between STAT proteins over the course of EAE development in critical lymphatic organs in vivo. In the present study, we demonstrate dramatic and progressive decrease of all six STAT family members (STAT1, STAT2, STAT3, STAT4, STAT5, STAT6) in the spleen and lymph nodes through the course of EAE development in SJL/J mice, in contrast with almost steady expression of thymic STAT proteins. Decreased splenic and lymphatic STAT expression was accompanied by significant enlargement of the spleen and lymph nodes, and histological proliferation of T cell areas with remodeling of the splenic microstructure in EAE mice. All STAT family members except STAT2 were mainly confined in T cell areas in spleen, whereas they were distributed in a protein specific manner in thymus. We present here a comprehensive analysis of all six members of the STAT family in spleen, lymph nodes and thymus through the development phase of EAE. Results suggest that EAE induced inflammatory T cells may develop distinct biological features different from normal splenic T cells due to altered STAT signaling.