IRGM1 enhances B16 melanoma cell metastasis through PI3K-Rac1 mediated epithelial mesenchymal transition

Virus replication is not required for oncolytic bovine herpesvirus-1 immunotherapy

Oncolytic viruses are a promising approach for cancer treatment where viruses selectively target and kill cancer cells while also stimulating an immune response. Among viruses with this ability, bovine herpesvirus-1 (BoHV-1) has several advantages, including observations suggesting it may not require viral replication for its anti-cancer effects. We previously demonstrated that binding and penetration of enveloped virus particles are sufficient to trigger intrinsic and innate immune signaling in normal cells, while other groups have published the efficacy of non-replicating viruses as viable immunotherapies in different cancer models. In this work, we definitively show that live and UV-inactivated (UV) (non-replicating) BoHV-1-based regimens extend survival of tumor-bearing mice to similar degrees and induce infiltration of similar immune cell populations, with the exception of neutrophils. Transcriptomic analysis of tumors treated with either live or UV BoHV-1-based regimens revealed similar pathway enrichment and a subset of overlapping differentially regulated genes, suggesting live and UV BoHV-1 have similar mechanisms of activity. Last, we present a gene signature across our in vitro and in vivo models that could potentially be used to validate new BoHV-1 therapeutics. This work contributes to the growing body of literature showing that replication may not be necessary for therapeutic efficacy of viral immunotherapies.

IL-33 stimulates the anticancer activities of eosinophils through extracellular vesicle-driven reprogramming of tumor cells

Immune cell-derived extracellular vesicles (EV) affect tumor progression and hold promise for therapeutic applications. Eosinophils are major effectors in Th2-related pathologies recently implied in cancer. Here, we evaluated the anti-tumor activities of eosinophil-derived EV following activation with the alarmin IL-33. We demonstrate that IL-33-activated mouse and human eosinophils produce higher quantities of EV with respect to eosinophils stimulated with IL-5. Following incorporation of EV from IL-33-activated eosinophils (Eo33-EV), but not EV from IL-5-treated eosinophils (Eo5-EV), mouse and human tumor cells increased the expression of cyclin-dependent kinase inhibitor (CDKI)-related genes resulting in cell cycle arrest in G0/G1, reduced proliferation and inhibited tumor spheroid formation. Moreover, tumor cells incorporating Eo33-EV acquired an epithelial-like phenotype characterized by E-Cadherin up-regulation, N-Cadherin downregulation, reduced cell elongation and migratory extent in vitro, and impaired capacity to metastasize to lungs when injected in syngeneic mice. RNA sequencing revealed distinct mRNA signatures in Eo33-EV and Eo5-EV with increased presence of tumor suppressor genes and enrichment in pathways related to epithelial phenotypes and negative regulation of cellular processes in Eo33-EV compared to Eo5-EV. Our studies underscore novel IL-33-stimulated anticancer activities of eosinophils through EV-mediated reprogramming of tumor cells opening perspectives on the use of eosinophil-derived EV in cancer therapy.

How did we get here? Insights into mechanisms of immunity-related GTPase targeting to intracellular pathogens

The cytokine gamma-interferon activates cell-autonomous immunity against intracellular bacterial and protozoan pathogens by inducing a slew of antimicrobial proteins, some of which hinge upon immunity-related GTPases (IRGs) for their function. Three regulatory IRG clade M (Irgm) proteins chaperone about approximately 20 effector IRGs (GKS IRGs) to localize to pathogen-containing vacuoles (PVs) within mouse cells, initiating a cascade that results in PV elimination and killing of PV-resident pathogens. However, the mechanisms that allow IRGs to identify and traffic specifically to 'non-self' PVs have remained elusive. Integrating recent findings demonstrating direct interactions between GKS IRGs and lipids with previous work, we propose that three attributes mark PVs as GKS IRG targets: the absence of membrane-bound Irgm proteins, Atg8 lipidation, and the presence of specific lipid species. Combinatorial recognition of these three distinct signals may have evolved as a mechanism to ensure safe delivery of potent host antimicrobial effectors exclusively to PVs.

Novel Mechanisms of Tumor Promotion by the Insulin Receptor Isoform A in Triple-Negative Breast Cancer Cells

The insulin receptor isoform A (IR-A) plays an increasingly recognized role in fetal growth and tumor biology in response to circulating insulin and/or locally produced IGF2. This role seems not to be shared by the IR isoform B (IR-B). We aimed to dissect the specific impact of IR isoforms in modulating insulin signaling in triple negative breast cancer (TNBC) cells. We generated murine 4T1 TNBC cells deleted from the endogenous insulin receptor (INSR) gene and expressing comparable levels of either human IR-A or IR-B. We then measured IR isoform-specific in vitro and in vivo biological effects and transcriptome in response to insulin. Overall, the IR-A was more potent than the IR-B in mediating cell migration, invasion, and in vivo tumor growth. Transcriptome analysis showed that approximately 89% of insulin-stimulated transcripts depended solely on the expression of the specific isoform. Notably, in cells overexpressing IR-A, insulin strongly induced genes involved in tumor progression and immune evasion including chemokines and genes related to innate immunity. Conversely, in IR-B overexpressing cells, insulin predominantly induced the expression of genes primarily involved in the regulation of metabolic pathways and, to a lesser extent, tumor growth and angiogenesis.

Opposing Roles of Type I Interferons in Cancer Immunity

The immune system is tasked with identifying malignant cells to eliminate or prevent cancer spread. This involves a complex orchestration of many immune cell types that together recognize different aspects of tumor transformation and growth. In response, tumors have developed mechanisms to circumvent immune attack. Type I interferons (IFN-Is) are a class of proinflammatory cytokines produced in response to viruses and other environmental stressors. IFN-Is are also emerging as essential drivers of antitumor immunity, potently stimulating the ability of immune cells to eliminate tumor cells. However, a more complicated role for IFN-Is has arisen, as prolonged stimulation can promote feedback inhibitory mechanisms that contribute to immune exhaustion and other deleterious effects that directly or indirectly permit cancer cells to escape immune clearance. We review the fundamental and opposing functions of IFN-Is that modulate tumor growth and impact immune function and ultimately how these functions can be harnessed for the design of new cancer therapies.

IRGM promotes melanoma cell survival through autophagy and is a promising prognostic biomarker for clinical application

Previously, we showed that mouse immunity-related guanosine triphosphatase (GTPase) family M protein 1 (Irgm1) promotes malignant melanoma progression by inducing cellular autophagy flux and metastasis. Human IRGM, a truncated protein functionally distinct from its mouse counterpart, has several splice isoforms. In this study, we analyzed the association of IRGM and human melanoma clinical prognosis and investigated the function of IRGM in human melanoma cells. Data from the training cohort (n = 144) showed that overexpression of IRGM is proportional to melanoma genesis and clinical stages in human tissue chips. A validation cohort (n = 78) further confirmed that IRGM is an independent risk factor promoting melanoma progression and is associated with poor survival of patients. Among IRGM isoforms, we found that IRGMb is responsible for such correlation. In addition, IRGM promoted melanoma cell survival through autophagy, both in vitro and in vivo. We further showed that the blockade of translocation of high-mobility group box 1 (HMGB1) from the nucleus to cytoplasm inhibits IRGM1-mediated cellular autophagy and reduces cell survival. IRGM functions as a positive regulator of melanoma progression through autophagy and may serve as a promising prognostic marker and therapeutic target.

High expression of immunity-related GTPase family M protein in glioma promotes cell proliferation and autophagy protein expression

Glioma is the commonest malignant tumor in the central nervous system (CNS), characterized by rapid growth. However, the molecular mechanism underlying the growth remains unclear. Immunity-related GTPase family M protein (IRGM) participates in immune response to pathogen and tumorigenesis. Proliferation and autophagy are two crucial functions contributing to aggressive growth. Therefore, our aims were to probe whether IRGM regulates glioma proliferation and autophagy. In this study, we found that 47 glioma specimens had more IRGM expression than 11 non-cancerous brain tissues with immunohistochemistry. IRGM was also up-regulated in human glioma cell lines U87, U251 and A172 and so on compared with immortalized astrocytes. Importantly, overexpression of IRGM significantly increased the cell colonies formation, cell proliferation and Akt activation (Thr308 and Ser473 sites) than matched control. On another hand, all of IRGM, autophagy marker LC3II and autophagy adaptor p62 gradually increased after starvation 2 and 4 h. Furthermore, western blot and immunofluorescence results showed that knockdown of IRGM inhibited the formation of LC3-II and the expression of p62. Our data uncovered that IRGM acted in glioma proliferation and autophagy, providing a new target with dual roles for the future translation research.

GDF15 promotes epithelial-to-mesenchymal transition in colorectal [corrected]

Growth differentiation factor 15 (GDF15) is a divergent member of the transforming growth factor-β (TGF-β) superfamily that has been associated with colorectal cancers (CRC). However, the role of GDF15 in the progression of CRC remains unknown. We demonstrated that GDF15 expression was higher in fresh CRC tissues than in adjacent normal tissues. Moreover, we found that GDF15 overexpression significantly facilitated cell viability, cell invasion and migration (p < .01 or p < .05). The protein expression of N-cadherin, vimentin and Twist1 were up-regulated by GDF15 overexpression, while E-cadherin was down-regulated. Reciprocally, using a GDF15-shRNA strategy, we observed that GDF15 downregulation inhibited both basal and GDF16-induced cell viability, invasion and migration in LoVo cells. In conclusion, GDF15 could promote cell viability, invasion and migration of LoVo cells through EMT induction.

Comprehensive gene expression analysis of canine invasive urothelial bladder carcinoma by RNA-Seq

BACKGROUND

Invasive urothelial carcinoma (iUC) is a major cause of death in humans, and approximately 165,000 individuals succumb to this cancer annually worldwide. Comparative oncology using relevant animal models is necessary to improve our understanding of progression, diagnosis, and treatment of iUC. Companion canines are a preferred animal model of iUC due to spontaneous tumor development and similarity to human disease in terms of histopathology, metastatic behavior, and treatment response. However, the comprehensive molecular characterization of canine iUC is not well documented. In this study, we performed transcriptome analysis of tissue samples from canine iUC and normal bladders using an RNA sequencing (RNA-Seq) approach to identify key molecular pathways in canine iUC.

METHODS

Total RNA was extracted from bladder tissues of 11 dogs with iUC and five healthy dogs, and RNA-Seq was conducted. Ingenuity Pathway Analysis (IPA) was used to assign differentially expressed genes to known upstream regulators and functional networks.

RESULTS

Differential gene expression analysis of the RNA-Seq data revealed 2531 differentially expressed genes, comprising 1007 upregulated and 1524 downregulated genes, in canine iUC. IPA revealed that the most activated upstream regulator was PTGER2 (encoding the prostaglandin E₂ receptor EP2), which is consistent with the therapeutic efficiency of cyclooxygenase inhibitors in canine iUC. Similar to human iUC, canine iUC exhibited upregulated ERBB2 and downregulated TP53 pathways. Biological functions associated with cancer, cell proliferation, and leukocyte migration were predicted to be activated, while muscle functions were predicted to be inhibited, indicating muscle-invasive tumor property.

CONCLUSIONS

Our data confirmed similarities in gene expression patterns between canine and human iUC and identified potential therapeutic targets (PTGER2, ERBB2, CCND1, Vegf, and EGFR), suggesting the value of naturally occurring canine iUC as a relevant animal model for human iUC.

The Adhesion G-Protein-Coupled Receptor, GPR56/ADGRG1, Inhibits Cell-Extracellular Matrix Signaling to Prevent Metastatic Melanoma Growth

Metastatic growth is considered a rate-limiting step in cancer progression, and upregulation of extracellular matrix (ECM) deposition and cell-ECM signaling are major drivers of this process. Mechanisms to reverse ECM upregulation in cancer could potentially facilitate its prevention and treatment but they are poorly understood. We previously reported that the adhesion G-protein-coupled receptor GPR56/ADGRG1 is downregulated in melanoma metastases. Its re-expression inhibited melanoma growth and metastasis and reduced the deposition of fibronectin, a major ECM component. We hypothesize that its effect on fibronectin deposition contributes to its inhibitory role on metastatic growth. To test this, we investigated the function of GPR56 on cell-fibronectin adhesion and its relationship with metastatic growth in melanoma. Our results reveal that GPR56 inhibits melanoma metastatic growth by impeding the expansion of micrometastases to macrometastases. Meanwhile, we present evidence that GPR56 inhibits fibronectin deposition and its downstream signaling, such as phosphorylation of focal adhesion kinase (FAK), during this process. Administration of the FAK inhibitor Y15 perturbed the proliferation of melanoma metastases, supporting a causative link between the cell adhesion defect induced by GPR56 and its inhibition of metastatic growth. Taken together, our results suggest that GPR56 in melanoma metastases inhibits ECM accumulation and adhesion, which contributes to its negative effects on metastatic growth.

A multigene support vector machine predictor for metastasis of cutaneous melanoma

Gene expression profiles of cutaneous melanoma were analyzed to identify critical genes associated with metastasis. Two gene expression datasets were downloaded from Gene Expression Omnibus (GEO) and another dataset was obtained from The Cancer Genome Atlas (TCGA). Differentially expression genes (DEGs) between metastatic and non‑metastatic melanoma were identified by meta‑analysis. A protein‑protein interaction (PPI) network was constructed for the DEGs using information from BioGRID, HPRD and DIP. Betweenness centrality (BC) was calculated for each node in the network and the top feature genes ranked by BC were selected to construct the support vector machine (SVM) classifier using the training set. The SVM classifier was then validated in another independent dataset. Pathway enrichment analysis was performed for the feature genes using Fisher's exact test. A total of 798 DEGs were identified and a PPI network including 337 nodes and 466 edges was then constructed. Top 110 feature genes ranked by BC were included in the SVM classifier. The prediction accuracies for the three datasets were 96.8, 100 and 94.4%, respectively. A total of 11 KEGG pathways and 13 GO biological pathways were significantly over‑represented in the 110 feature genes, including endometrial cancer, regulation of actin cytoskeleton, focal adhesion, ubiquitin mediated proteolysis, regulation of apoptosis and regulation of cell proliferation. A SVM classifier of high prediction accuracy was acquired. Several critical genes implicated in melanoms metastasis were also revealed. These results may advance understanding of the molecular mechanisms underlying metastasis, and also provide potential therapeutic targets.

RUFY3 interaction with FOXK1 promotes invasion and metastasis in colorectal cancer

RUFY3 is highly expressed in brain tissue and has a role in neuronal development. Transcriptional factor FOXK1 is involved in cell growth and metabolism. We knew that RUFY3 or FOXK1 has been correlated with the malignant of tumor cells. However, the role of these molecules in colorectal cancer (CRC) progression remains unknown. We investigated the protein expression levels by Western blot, immunofluorescence and immunohistochemistry analyses. The migration and invasive abilities of CRC cells were assessed using shRNA-mediated inhibition in vitro and in vivo. We showed that RUFY3 expression was up-regulated in CRC compared with its expression in a normal human colon cell line (FHC). RUFY3 suppression inhibited anchorage independent cell tumorigenesis. RUFY3 induced elevated expression of eight major oncogenes. Moreover, RUFY3 physically interacts with FOXK1 in CRC. A positive correlation was observed between the expression patterns of RUFY3 and FOXK1. Furthermore, RUFY3 and FOXK1 expression were correlated with tumor progression and represented significant predictors of overall survival in CRC patients. SiRNA-mediated repression of FOXK1 in RUFY3-overexpressing cells reversed the epithelial-mesenchymal transition (EMT) and metastatic phenotypes. In vivo, FOXK1 promoted RUFY3-mediated metastasis via orthotopic implantation. These findings suggest that the RUFY3-FOXK1 axis might promote the development and progression of human CRC.

Epithelial-mesenchymal transition of ovarian cancer cells is sustained by Rac1 through simultaneous activation of MEK1/2 and Src signaling pathways

Epithelial-mesenchymal transition (EMT) is regarded as a crucial contributing factor to cancer progression. Diverse factors have been identified as potent EMT inducers in ovarian cancer. However, molecular mechanism sustaining EMT of ovarian cancer cells remains elusive. Here we show that the presence of SOS1/EPS8/ABI1 complex is critical for sustained EMT traits of ovarian cancer cells. Consistent with the role of SOS1/EPS8/ABI1 complex as a Rac1-specific guanine nucleotide exchange factor, depleting Rac1 results in the loss of most of mesenchymal traits in mesenchymal-like ovarian cancer cells, whereas expressing constitutively active Rac1 leads to EMT in epithelial-like ovarian cancer cells. With the aid of clinically tested inhibitors targeting various EMT-associated signaling pathways, we show that only combined treatment of mitogen-activated extracellular signal-regulated kinase 1/2 (MEK1/2) and Src inhibitors can abolish constitutively active Rac1-led EMT and mesenchymal traits displayed by mesenchymal-like ovarian cancer cells. Further experiments also reveal that EMT can be induced in epithelial-like ovarian cancer cells by co-expressing constitutively active MEK1 and Src rather than either alone. As the activities of Erk and Src are higher in ovarian cancer cells with constitutively active Rac1, we conclude that Rac1 sustains ovarian cancer cell EMT through simultaneous activation of MEK1/2 and Src signaling pathways. Importantly, we demonstrate that combined use of MEK1/2 and Src inhibitors effectively suppresses development of intraperitoneal xenografts and prolongs the survival of ovarian cancer-bearing mice. This study suggests that cocktail of MEK1/2 and Src inhibitors represents an effective therapeutic strategy against ovarian cancer progression.

Therapeutic implications of cellular and molecular biology of cancer stem cells in melanoma

Melanoma is a form of cancer that initiates in melanocytes. Melanoma has multiple phenotypically distinct subpopulation of cells, some of them have embryonic like plasticity which are involved in self-renewal, tumor initiation, metastasis and progression and provide reservoir of therapeutically resistant cells. Cancer stem cells (CSCs) can be identified and characterized based on various unique cell surface and intracellular markers. CSCs exhibit different molecular pattern with respect to non-CSCs. They maintain their stemness and chemoresistant features through specific signaling cascades. CSCs are weak in immunogenicity and act as immunosupressor in the host system. Melanoma treatment becomes difficult and survival is greatly reduced when the patient develop metastasis. Standard conventional oncology treatments such as chemotherapy, radiotherapy and surgical resection are only responsible for shrinking the bulk of the tumor mass and tumor tends to relapse. Thus, targeting CSCs and their microenvironment niche addresses the alternative of traditional cancer therapy. Combined use of CSCs targeted and traditional therapies may kill the bulk tumor and CSCs and offer a promising therapeutic strategy for the management of melanoma.

Rufy3 promotes metastasis through epithelial-mesenchymal transition in colorectal cancer

Rufy3 is a RUN domain-containing protein that has been associated with gastric cancers; however, the role of Rufy3 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that Rufy3 expression was higher in 11/12 fresh CRC tissues than in adjacent normal tissues. Rufy3 induced elevated expression and transactivity of four major oncogenes in CRC. Moreover, siRNA-mediated repression of Rufy3 induced G0/G1 cell cycle arrest, and Rufy3 overexpression enhanced CRC cell proliferation in vitro and in vivo. Furthermore, Rufy3 up-regulation promoted epithelial-mesenchymal transition (EMT) and metastatic phenotypes. Using an established in vitro cell model of 5-fluorouracil-resistant (5-FU) CRC cells, we assessed cellular morphology, molecular changes, and invasion and found that these characteristics were consistent with EMT. Silencing of Rufy3 by siRNA reversed EMT and greatly diminished the invasion of 5-FU-treated cells. In addition, TGF-β1 induced Rufy3 expression in a dose-dependent manner, and Rufy3 knockdown inhibited TGF-β1-induced EMT. In vivo, higher expression of Rufy3 promoted CRC cell invasion and metastasis and induced EMT. Taken together, this work identified that Rufy3 promoted cancer metastasis in CRC cells through EMT induction.

Dynamins and BAR Proteins-Safeguards against Cancer

Dynamins and BAR proteins are crucial in a wide variety of cellular processes for their ability to mediate membrane remodeling, such as membrane curvature and membrane fission and fusion. In this review, we highlight dynamins and BAR proteins and the cellular mechanisms that are involved in the initiation and progression of cancer. We specifically discuss the roles of the seproteinsin endocytosis, endo-lysosomal trafficking, autophagy, and apoptosis as these processes are all tightly linked to membrane remodeling and cancer.