Activation of the IL-4/STAT6 Signaling Pathway Promotes Lung Cancer Progression by Increasing M2 Myeloid Cells

STAT6 contributes to renal fibrosis by modulating PPARα-mediated tubular fatty acid oxidation

Lipid metabolism, especially fatty acid oxidation (FAO) dysfunction, is a major driver of renal fibrosis; however, the detailed regulatory mechanisms involved remain unclear. In this study, we showed that there existed an association between the signal transducer and activator of transcription 6 (STAT6) and tubular lipid metabolism in fibrotic kidneys. Specifically, STAT6 was activated along with the accumulation of lipids via the downregulation of FAO-related genes when mice were subjected to unilateral ureteral obstruction (UUO) or high-fat diet challenge. Tubular-specific depletion, or pharmacologic inhibitor of Stat6 in mice, and Stat6 knockdown in cultured tubular cells attenuated lipid accumulation and renal fibrosis by enhancing FAO. Mechanistically, STAT6 transcriptionally inhibited the expression of PPARα and its FAO-related target genes through a sis-inducible element located in the promoter region of the protein. In conclusion, our study demonstrates the mechanistic details of STAT6-mediated FAO dysregulation in the progression of renal fibrosis and provides a preclinical rationale for efforts to improve the management of renal fibrosis brought about by FAO dysregulation.

Prognostic value and immune infiltration of a novel stromal/immune score-related P2RY12 in lung adenocarcinoma microenvironment

OBJECTIVE

Increasing evidence highlights the clinical implications of P2RY12 that belongs to the family of G-protein coupled receptors in carcinogenesis. Here, this study was designed to explore the associations between P2RY12 and tumor immune microenvironment of lung adenocarcinoma (LUAD).

METHODS

Based on 352 LUAD samples from The Cancer Genome Atlas (TCGA), stromal and immune scores of each sample were estimated by ESTIMATE algorithm. Differential expression analysis was presented between stromal/immune high- and low-score groups. Protein-protein interaction (PPI) was then constructed by STRING database. Univariate and multivariate Cox regression analysis was utilized to screen prognosis-related factors. Co-expressed genes of P2RY12 were analyzed, followed by functional enrichment analysis. Furthermore, the correlation between P2RY12 and immune cell infiltrations was estimated using the TIMER database. P2RY12 expression was validated between 37 pairs of LUAD and normal tissues using RT-qPCR and immunohistochemistry. After overexpressing P2RY12, the proliferation and migration of A549 cells was detected by CCK-8 and scratch test.

RESULTS

145 up- and 102 down-regulated stromal- and immune-related mRNAs were identified for LUAD. Based on 145 up-regulated mRNAs, a PPI network was conducted, consisting of 95 nodes and 210 relationship pairs. Ten hub genes were then identified. Among them, CCR8, CNR2, CXCR5, GPR18, GPR31 and P2RY12 were in association with overall survival of patients with LUAD. After adjusting other variables, P2RY12 expression was an independent prognostic factor for LUAD. 288 co-expressed genes of P2RY12 were determined and these co-expressed genes were primarily involved in immune-related biological processes or pathways. Moreover, P2RY12 was significantly correlated with M2 macrophage and dendritic cell infiltration. After validation, P2RY12 expression was significantly decreased in LUAD than normal tissues. Its overexpression distinctly suppressed proliferation and migration of A549 cells.

CONCLUSION

Our findings suggest that P2RY12 is an immune infiltration-related prognostic marker for LUAD.

Targeting monoamine oxidase A-regulated tumor-associated macrophage polarization for cancer immunotherapy

Targeting tumor-associated macrophages (TAMs) is a promising strategy to modify the immunosuppressive tumor microenvironment and improve cancer immunotherapy. Monoamine oxidase A (MAO-A) is an enzyme best known for its function in the brain; small molecule MAO inhibitors (MAOIs) are clinically used for treating neurological disorders. Here we observe MAO-A induction in mouse and human TAMs. MAO-A-deficient mice exhibit decreased TAM immunosuppressive functions corresponding with enhanced antitumor immunity. MAOI treatment induces TAM reprogramming and suppresses tumor growth in preclinical mouse syngeneic and human xenograft tumor models. Combining MAOI and anti-PD-1 treatments results in synergistic tumor suppression. Clinical data correlation studies associate high intratumoral MAOA expression with poor patient survival in a broad range of cancers. We further demonstrate that MAO-A promotes TAM immunosuppressive polarization via upregulating oxidative stress. Together, these data identify MAO-A as a critical regulator of TAMs and support repurposing MAOIs for TAM reprogramming to improve cancer immunotherapy.

STAT6: A review of a signaling pathway implicated in various diseases with a special emphasis in its usefulness in pathology

Signal Transducer and Activator of Transcription 6 (STAT6), belonging to a family of seven similar members is primarily stimulated by interleukin(IL)-4 and IL-13, and acts as a T helper type 2 (Th2)-inducing factor. Thus, it is implicated in the pathophysiology of various allergic conditions, such as asthma, atopic dermatitis, eosinophilic esophagitis and food allergies, but also in tumor microenvironment regulation. Furthermore, certain forms of lymphomas, notably the Hodgkin lymphoma group, the primary mediastinal and primary central nervous system lymphoma, as well as some follicular and T cell lymphomas are associated with dysregulation of the STAT6 pathway. STAT6 immunohistochemical expression also serves as a surrogate marker in the diagnosis of solitary fibrous tumor, despite not directly responsible for the tumorigenic effect. These pathophysiological implications of the STAT6 pathway, its diagnostic or prognostic role in pathology, as well its immunohistochemical detection with different antibodies will be discussed in this review.

Differentiation and Regulation of TH Cells: A Balancing Act for Cancer Immunotherapy

Current success of immunotherapy in cancer has drawn attention to the subsets of T_H cells in the tumor which are critical for activation of anti-tumor response either directly by themselves or by stimulating cytotoxic T cell activity. However, presence of immunosuppressive pro-tumorigenic T_H subsets in the tumor milieu further contributes to the complexity of regulation of T_H cell-mediated immune response. In this review, we present an overview of the multifaceted positive and negative effects of T_H cells, with an emphasis on regulation of different T_H cell subtypes by various immune cells, and how a delicate balance of contradictory signals can influence overall success of cancer immunotherapy. We focus on the regulatory network that encompasses dendritic cell-induced activation of CD4⁺ T_H1 cells and subsequent priming of CD8⁺ cytotoxic T cells, along with intersecting anti-inflammatory and pro-tumorigenic T_H2 cell activity. We further discuss how other tumor infiltrating immune cells such as immunostimulatory T_H9 and T_fh cells, immunosuppressive T_reg cells, and the duality of T_H17 function contribute to tip the balance of anti- vs pro-tumorigenic T_H responses in the tumor. We highlight the developing knowledge of CD4⁺ T_H1 immune response against neoantigens/oncodrivers, impact of current immunotherapy strategies on CD4⁺ T_H1 immunity, and how opposing action of T_H cell subtypes can be explored further to amplify immunotherapy success in patients. Understanding the nuances of CD4⁺ T_H cells regulation and the molecular framework undergirding the balancing act between anti- vs pro-tumorigenic T_H subtypes is critical for rational designing of immunotherapies that can bypass therapeutic escape to maximize the potential of immunotherapy.

Involvement of IL-4, IL-13 and Their Receptors in Pancreatic Cancer

Interleukin (IL)-4 and IL-13 are known as pleiotropic Th2 cytokines with a wide range of biological properties and functions especially in immune responses. In addition, increasing activities have also been determined in oncogenesis and tumor progression of several malignancies. It is now generally accepted that IL-4 and IL-13 can exert effects on epithelial tumor cells through corresponding receptors. Type II IL-4 receptor (IL-4Rα/IL-13Rα1), predominantly expressed in non-hematopoietic cells, is identified to be the main target for both IL-4 and IL-13 in tumors. Moreover, IL-13 can also signal by binding to the IL-13Rα2 receptor. Structural similarity due to the use of the same receptor complex generated in response to IL-4/IL-13 results in overlapping but also distinct signaling pathways and functions. The aim of this review was to summarize knowledge about IL-4 and IL-13 and their receptors in pancreatic cancer in order understand the implication of IL-4 and IL-13 and their receptors for pancreatic tumorigenesis and progression and for developing possible new diagnostic and therapeutic targets.

High-throughput sequencing profile of laryngeal cancers: analysis of co-expression and competing endogenous RNA networks of circular RNAs, long non-coding RNAs, and messenger RNAs

Background

Circular RNAs (circRNAs) and long non-coding RNAs (lncRNAs) have been recently identified as new classes of non-coding RNAs which participate in carcinogenesis and tumor progression. However, the functions of these non-coding RNAs and gene expression patterns are largely unknown.

Methods

We carried out high-throughput sequencing to analyze the differential expression of RNAs in 5 coupled laryngeal cancer (LC) and corresponding adjacent noncancerous tissues. Bioinformatics analyses were performed to predict the functions of these non-coding RNAs via co-expression, competing endogenous RNA networks and pathway enrichment analysis. The differential expression of the selected RNAs were confirmed using RT-qPCR. The CCK8, EDU, Transwell, and wound healing assays were conducted to validate the biological functions of SNHG29 in LC. Western blot assay was performed to identify the effects of SNHG29 having on the epithelial to mesenchymal transition process. Kaplan-Meier analysis was used to investigate whether the expression level of SNHG29 correlated with survival in LC patients. One-way ANOVA was used to analyze the correlation between the expression of SNHG29 and clinicopathological parameters of the included patients.

Results

Compared to normal laryngeal tissues, 31,763 non-coding RNAs were upregulated and 11,557 non-coding RNAs were downregulated in cancer tissues. SNHG29 expression was low in the LC cell lines and tissues predicting a better clinical prognosis. SNHG29 was also found to inhibit the proliferation, migration, and invasion ability of LC, exerting a suppressive role in the epithelial to mesenchymal transition process as well. SNHG29 downregulation was significantly correlated with differentiation (P=0.026), T-stage (P=0.041), lymphatic metastasis (P=0.044), and clinical stage (P=0.037). We found that the biological functions of differentially expressed transcripts included cell adhesion, biological adhesion, and migration and invasion related to adherens junction pathways.

Conclusions

Our study was the first to describe the non-coding RNA profile of LC, and suggested that dysregulated non-coding RNAs could be involved in LC tumorigenesis. SNHG29 was demonstrated to play crucial roles in inhibiting the pathogenesis and progression of LC. Our findings provide a new approach for further analyses of pathogenetic mechanisms, the detection of novel transcripts, and the identification of valuable biomarkers for this tumor.

Tumor-Associated Macrophages: New Horizons for Pituitary Adenoma Researches

Macrophages are one of the most common infiltrating immune cells and an essential component of tumor microenvironment. Macrophages and the soluble cytokines and chemokines produced play an important role in tumorigenesis, progression, invasion and metastasis in solid tumors. Despite the multiple studies in other solid tumors, there is little known about macrophages in pituitary adenomas. Recently, studies about pituitary adenoma-infiltrated macrophages have been emerging, including the immunohistochemical and immunophenotypic analysis of the pituitary adenomas and further studies into the mechanism of the crosstalk between macrophages and tumor cells in vivo and in vitro. These studies have offered us new insights into the polarization of macrophages and its role in tumorigenesis, progression and invasion of pituitary adenomas. This review describes the advances in the field of pituitary adenoma-infiltrated macrophages and the prospect of targeting macrophages as cancer therapy in pituitary adenoma.

The roles of post-translational modifications and coactivators of STAT6 signaling in tumor growth and progression

Signal transducers and activators of transcription 6 (STAT6) are highly expressed in various tumors and associated with tumorigenesis, immunosuppression, proliferation, metastasis and poor prognosis in human cancers. In response to IL-4/13, STAT6 is phosphorylated, dimerizes and triggers transcriptional regulation after recruitment of coactivators to transcriptosome, such as CBP/p300, SRC-1, PARP-14 and PSF. Post-translational modifications, including phosphorylation, ubiquitination, ADP-ribosylation and acetylation, have been explored for molecular mechanisms of STAT6 in tumor development and management. STAT6 has been developed as a specific biomarker for distinguishing and diagnosing tumor phenotypes, although it is observed to be frequently mutated in metastatic tumors. In this article, we focus mainly on the structural characteristics of STAT6 and its role in tumor growth and progression.

Use of STAT6 Phosphorylation Inhibitor and Trimethylglycine as New Adjuvant Therapies for 5-Fluorouracil in Colitis-Associated Tumorigenesis

Colorectal cancer (CRC) is one of the most widespread and deadly types of neoplasia around the world, where the inflammatory microenvironment has critical importance in the process of tumor growth, metastasis, and drug resistance. Despite its limited effectiveness, 5-fluorouracil (5-FU) is the main drug utilized for CRC treatment. The combination of 5-FU with other agents modestly increases its effectiveness in patients. Here, we evaluated the anti-inflammatory Trimethylglycine and the Signal transducer and activator of transcription (STAT6) inhibitor AS1517499, as possible adjuvants to 5-FU in already established cancers, using a model of colitis-associated colon cancer (CAC). We found that these adjuvant therapies induced a remarkable reduction of tumor growth when administrated together with 5-FU, correlating with a reduction in STAT6-phosphorylation. This reduction upgraded the effect of 5-FU by increasing both levels of apoptosis and markers of cell adhesion such as E-cadherin, whereas decreased epithelial-mesenchymal transition markers were associated with aggressive phenotypes and drug resistance, such as β-catenin nuclear translocation and Zinc finger protein SNAI1 (SNAI1). Additionally, Il-10, Tgf-β, and Il-17a, critical pro-tumorigenic cytokines, were downmodulated in the colon by these adjuvant therapies. In vitro assays on human colon cancer cells showed that Trimethylglycine also reduced STAT6-phosphorylation. Our study is relatively unique in focusing on the effects of the combined administration of AS1517499 and Trimethylglycine together with 5-FU on already established CAC which synergizes to markedly reduce the colon tumor load. Together, these data point to STAT6 as a valuable target for adjuvant therapy in colon cancer.