BMP4 inhibits breast cancer metastasis by blocking myeloid-derived suppressor cell activity

Inflammatory gene regulation by Cdc42 in airway epithelial cells

Cytokine release from airway epithelial cells is a key immunological process that coordinates an immune response in the lungs. We propose that the Rho GTPase, Cdc42, regulates both transcription and trafficking of cytokines, ultimately affecting the essential process of cytokine release and subsequent inflammation in the lungs. Here, we examined the pro-inflammatory transcriptional profile that occurs in bronchial epithelial cells (BEAS-2B) in response to TNF-α using RNA-Seq and differential gene expression analysis. To interrogate the role of Cdc42 in inflammatory gene expression, we used a pharmacological inhibitor of Cdc42, ML141, and determined changes in the transcriptomic profile induced by Cdc42 inhibition. Our results indicated that Cdc42 inhibition with ML141 resulted in a unique inflammatory phenotype concomitant with increased gene expression of ER stress genes, Golgi membrane and vesicle transport genes. To further interrogate the inflammatory pathways regulated by Cdc42, we made BEAS-2B knockdown strains for the signaling targets TRIB3, DUSP5, SESN2 and BMP4, which showed high differential expression in response to Cdc42 inhibition. Depletion of DUSP5 and TRIB3 reduced the pro-inflammatory response triggered by Cdc42 inhibition as shown by a reduction in cytokine transcript levels. Depletion of SESN2 and BMP4 did not affect cytokine transcript level, however, Golgi fragmentation was reduced. These results provide further evidence that in airway epithelial cells, Cdc42 is part of a signaling network that controls inflammatory gene expression and secretion by regulating Golgi integrity. Summary sentence:We define the Cdc42-regulated gene networks for inflammatory signaling in airway epithelial cells which includes regulation of ER stress response and vesicle trafficking pathways.

The role of host response to chemotherapy: resistance, metastasis and clinical implications

Chemotherapy remains the primary treatment for most metastatic cancers. However, the response to chemotherapy and targeted agents is often transient, and concurrent development of resistance is the primary impediment to effective cancer therapy. Strategies to overcome resistance to treatment have focused on cancer cell intrinsic factors and the tumor microenvironment (TME). Recent evidence indicates that systemic chemotherapy has a significant impact on the host that either facilitates tumor growth, allowing metastatic spread, or renders treatment ineffective. These host responses include the release of bone marrow-derived cells, activation of stromal cells in the TME, and induction of different molecular effectors. Here, we provide an overview of chemotherapy-induced systemic host responses that support tumor aggressiveness and metastasis, and which contribute to therapy resistance. Studying host responses to chemotherapy provides a solid basis for the development of adjuvant strategies to improve treatment outcomes and delay resistance to chemotherapy. This review discusses the emerging field of host response to cancer therapy, and its preclinical and potential clinical implications, explaining how under certain circumstances, these host effects contribute to metastasis and resistance to chemotherapy.

Granulocyte colony-stimulating factor has the potential to attenuate the therapeutic efficacy of chemo-immunotherapy for extensive-stage small-cell lung cancer

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) has the potential to attenuate the anti-tumor immune responses of T-cells by increasing immune suppressive neutrophils and myeloid-derived suppressor cells. However, the clinical impact of G-CSF on the efficacy of immunotherapy remains unknown. This multi-center retrospective analysis evaluated the impact of G-CSF in patients with extensive-stage small-cell lung cancer (ES-SCLC) treated with chemo-immunotherapy.

METHODS

We analyzed 65 patients with ES-SCLC who completed four cycles of induction chemo-immunotherapy and evaluated the effects of G-CSF on progression-free survival (PFS), overall survival (OS), and a durable response to immunotherapy (defined as PFS ≥ 12 months).

RESULTS

Fifty patients (76.9%) received ≥ 1 dose of G-CSF. The PFS of the patients with G-CSF was poorer than that of the patients without G-CSF (median PFS 8.3 vs. 4.9 months, p = 0.009). The OS of the patients with G-CSF tended to be shorter, but not statistically significant, than that of the patients without G-CSF (median OS 24.3 vs. 16.4 months, p = 0.137). In the multivariate analysis, G-CSF administration was associated with poorer PFS (hazard ratio 2.78, 95% CI 1.36-5.69, p = 0.005) and was identified as a determinant of a durable response (odds ratio 0.18, 95% CI 0.04-0.80, p = 0.024). These results were consistent with other definitions of G-CSF administration (administration of ≥ 1 dose of pegfilgrastim, or either ≥ 5 doses of filgrastim or ≥ 1 dose of pegfilgrastim).

CONCLUSIONS

G-CSF has the potential to attenuate the efficacy of immunotherapy; therefore, the indication for G-CSF during chemo-immunotherapy should be carefully considered for ES-SCLC.

Loss of tumor-derived SMAD4 enhances primary tumor growth but not metastasis following BMP4 signalling

BACKGROUND

Bone morphogenetic protein 4 (BMP4) is a potent inhibitor of breast cancer metastasis. However, a tumor-promoting effect of BMP4 is reported in other tumor types, especially when SMAD4 is inactive.

METHODS

To assess the requirement for SMAD4 in BMP4-mediated suppression of metastasis, we knocked down SMAD4 in two different breast tumors and enforced SMAD4 expression in a third line with endogenous SMAD4 deletion. In addition, we assessed the requirement for SMAD4 in tumor cell-specific BMP signalling by expression of a constitutively active BMP receptor. Delineation of genes regulated by BMP4 in the presence or absence of SMAD4 was assessed by RNA sequencing and a BMP4-induced gene, MYO1F was assessed for its role in metastasis. Genes regulated by BMP4 and/or SMAD4 were assessed in a publicly available database of gene expression profiles of breast cancer patients.

RESULTS

In the absence of SMAD4, BMP4 promotes primary tumor growth that is accompanied by increased expression of genes associated with DNA replication, cell cycle, and MYC signalling pathways. Despite increased primary tumor growth, BMP4 suppresses metastasis in the absence of tumor cell expression of SMAD4. Consistent with the anti-metastatic activity of BMP4, enforced signalling through the constitutively active receptor in SMAD4 positive tumors that lacked BMP4 expression still suppressed metastasis, but in the absence of SMAD4, the suppression of metastasis was largely prevented. Thus BMP4 is required for suppression of metastasis regardless of tumor SMAD4 status. The BMP4 upregulated gene, MYO1F, was shown to be a potent suppressor of breast cancer metastasis. Gene signature upregulated by BMP4 in the absence of SMAD4 was associated with poor prognosis in breast cancer patients, whereas gene signature upregulated by BMP4 in the presence of SMAD4 was associated with improved prognosis.

CONCLUSIONS

BMP4 expression is required for suppression of metastasis regardless of the SMAD4 status of the tumor cells. Since BMP4 is a secreted protein, we conclude that it can act both in an autocrine manner in SMAD4-expressing tumor cells and in a paracrine manner on stromal cells to suppress metastasis. Deletion of SMAD4 from tumor cells does not prevent BMP4 from suppressing metastasis via a paracrine mechanism.

IRS1 promotes thyroid cancer metastasis through EMT and PI3K/AKT pathways

OBJECTIVE

Insulin receptor substract 1 (IRS1) protein is an important signal transduction adapter for extracellular signal transduction from insulin-like growth factor-1 receptor and its family members to IRS1 downstream proteins. IRS1 has been reported to be involved in tumourigenesis and metastasis in some of solid tumors. Investigating the role of IRS1 in thyroid cancer can help to screen high risk patients at the initial diagnosis.

DESIGN, PATIENTS AND MEASUREMENTS

Immunohistochemical assay was used to detect the expression levels of IRS1 in 131 metastatic thyroid cancer tissues. Wound healing, cell invasion and colony formation assays were used to study the functions of IRS1 in vitro. RNA sequencing (RNA-seq) and Western blot analysis analyses were performed to examine the underlying regulation mechanisms of IRS1 in thyroid cancer cells.

RESULTS

IRS1 was highly expressed in thyroid cancers and its expression was positively associated with distant metastasis and advanced clinical stages. In vitro studies demonstrated that IRS1 is an important mediator of migration, invasion and colony formation of thyroid cancer cells. RNA-seq showed that IRS1 promoted the metastasis of thyroid cancer by regulating epithelial-mesenchymal transition and phosphoinositide 3-kinase (PI3K)/AKT pathway.

CONCLUSIONS

IRS1 overexpression contributes to the aggressiveness of thyroid cancer and is expected to be a stratified marker and a potential therapeutic target for thyroid cancer.

Myeloid-derived suppressor cells in cancer and cancer therapy

Anticancer agents continue to dominate the list of newly approved drugs, approximately half of which are immunotherapies. This trend illustrates the considerable promise of cancer treatments that modulate the immune system. However, the immune system is complex and dynamic, and can have both tumour-suppressive and tumour-promoting effects. Understanding the full range of immune modulation in cancer is crucial to identifying more effective treatment strategies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid cells that develop in association with chronic inflammation, which is a hallmark of cancer. Indeed, MDSCs accumulate in the tumour microenvironment, where they strongly inhibit anticancer functions of T cells and natural killer cells and exert a variety of other tumour-promoting effects. Emerging evidence indicates that MDSCs also contribute to resistance to cancer treatments, particularly immunotherapies. Conversely, treatment approaches designed to eliminate cancer cells can have important additional effects on MDSC function, which can be either positive or negative. In this Review, we discuss the interplay between MDSCs and various other cell types found in tumours as well as the mechanisms by which MDSCs promote tumour progression. We also discuss the relevance and implications of MDSCs for cancer therapy.

Unique macrophage phenotypes activated by BMP signaling in breast cancer bone metastases

Metastatic breast cancer (mBC) tissue in bone was systematically profiled to define the composition of the tumor microenvironment. Gene expression identified a high myeloid signature of patients with improved survival outcomes. Bone metastases were profiled by spatial proteomics to examine myeloid populations within the stroma that correlated with macrophage functions. Single-cell spatial analysis uncovered macrophage activation in the stroma of mBC bone lesions. Matched BC patient samples of primary breast tumor and bone metastasis tissues were compared for gene expression in the bone, where bone morphogenetic protein 2 (BMP2) was most significantly upregulated. Immune cell changes from breast to bone demonstrated a loss of lymphoid cells but a consistent population of macrophages. BMP-activated macrophages were increased uniquely in bone. Bone marrow-derived macrophage activation coupled with BMP inhibition increased inflammatory responses. Using experimental mouse models of mBC bone metastasis and trained immunity, we found that BMP inhibition restricts progression of metastases early in the macrophage activation state but not after tumors were established in the bone. This study revealed unique myeloid BMP activation states that are distinctly integrated with bone metastases.

Stemness signature and targeted therapeutic drugs identification for Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and carries the worst prognosis, characterized by the lack of progesterone, estrogen, and HER2 gene expression. This study aimed to analyze cancer stemness-related gene signature to determine patients' risk stratification and prognosis feature with TNBC. Here one-class logistic regression (OCLR) algorithm was applied to compute the stemness index of TNBC patients. Cox and LASSO regression analysis was performed on stemness-index related genes to establish 16 genes-based prognostic signature, and their predictive performance was verified in TCGA and METABERIC merged data cohort. We diagnosed the expression level of prognostic genes signature in the tumor immune microenvironment, analyzed the TNBC scRNA-seq GSE176078 dataset, and further validated the expression level of prognostic genes using the HPA database. Finally, the small molecular compounds targeted at the anti-tumor effect of predictive genes were screened by molecular docking; this novel stemness-based prognostic genes signature study could facilitate the prognosis of patients with TNBC and thus provide a feasible therapeutic target for TNBC.

Open-labeled, multicenter phase II study of prophylactic administration of pegylated granulocyte colony-stimulating factor in relapsed or refractory multiple myeloma who received pomalidomide-based regimens (KMM170)

Introduction

Pegylated granulocyte colony-stimulating factor (G-CSF) has been widely used for preventing febrile neutropenia in various types of cancer treatment. In the present study, we prospectively evaluated the safety and efficacy of pegfilgrastim as a primary prophylaxis of febrile neutropenia and infection among patients with relapsed refractory multiple myeloma (RRMM) treated with pomalidomide-based regimens.

Methods

Thirty-three patients with RRMM who received pomalidomide and dexamethasone (Pd) with or without cyclophosphamide (PCd) were enrolled in this study. Twenty-eight patients were treated with PCd and 5 patients were treated with Pd. All patients were given pegfilgrastim subcutaneously with a single administration performed on the first day of each cycle as primary prophylaxis until the fourth cycle.

Results

The median age of the patients was 75 (range 56-85), and the median prior line of therapy was 2 (range 2-6). Seventeen patients (51.5%) had any grade of neutropenia and 20 (60.6%) had any grade of thrombocytopenia before starting pomalidomide treatment. During the 4 cycles of treatment, grade 3 or more neutropenia occurred in 17 patients (51.5%), and 4 (12.1%) experienced grade 3 or more febrile neutropenia. Grade 3 or more infections occurred in 5 patients (15.2%). Interestingly, the patients with markedly increased ANC of more than 2 x 109/L compared to baseline ANC after 7 days of pegfilgrastim at 1st cycle of treatment showed a significantly lower incidence of grade 3-4 neutropenia. The most common adverse event of pegfilgrastim was fatigue, and all the adverse events caused by pegfilgrastim were grade 1 or 2. And there was no significant change in the immune cell population and cytokines during the administration of pegfilgrastim.

Discussion

Considering that this study included elderly patients with baseline neutropenia, pegylated G-CSF could be helpful to prevent severe neutropenia, febrile neutropenia, or infection in patients with RRMM.

MDSCs in breast cancer: an important enabler of tumor progression and an emerging therapeutic target

Women worldwide are more likely to develop breast cancer (BC) than any other type of cancer. The treatment of BC depends on the subtype and stage of the cancer, such as surgery, radiotherapy, chemotherapy, and immunotherapy. Although significant progress has been made in recent years, advanced or metastatic BC presents a poor prognosis, due to drug resistance and recurrences. During embryonic development, myeloid-derived suppressor cells (MDSCs) develop that suppress the immune system. By inhibiting anti-immune effects and promoting non-immune mechanisms such as tumor cell stemness, epithelial-mesenchymal transformation (EMT) and angiogenesis, MDSCs effectively promote tumor growth and metastasis. In various BC models, peripheral tissues, and tumor microenvironments (TME), MDSCs have been found to amplification. Clinical progression or poor prognosis are strongly associated with increased MDSCs. In this review, we describe the activation, recruitment, and differentiation of MDSCs production in BC, the involvement of MDSCs in BC progression, and the clinical characteristics of MDSCs as a potential BC therapy target.

Defining the Emergence of New Immunotherapy Approaches in Breast Cancer: Role of Myeloid-Derived Suppressor Cells

Breast cancer (BC) continues to be the most diagnosed tumor in women and a very heterogeneous disease both inter- and intratumoral, mainly given by the variety of molecular profiles with different biological and clinical characteristics. Despite the advancements in early detection and therapeutic strategies, the survival rate is low in patients who develop metastatic disease. Therefore, it is mandatory to explore new approaches to achieve better responses. In this regard, immunotherapy arose as a promising alternative to conventional treatments due to its ability to modulate the immune system, which may play a dual role in this disease since the relationship between the immune system and BC cells depends on several factors: the tumor histology and size, as well as the involvement of lymph nodes, immune cells, and molecules that are part of the tumor microenvironment. Particularly, myeloid-derived suppressor cell (MDSC) expansion is one of the major immunosuppressive mechanisms used by breast tumors since it has been associated with worse clinical stage, metastatic burden, and poor efficacy of immunotherapies. This review focuses on the new immunotherapies in BC in the last five years. Additionally, the role of MDSC as a therapeutic target in breast cancer will be described.

Xuanhusuo powder has an anti-breast cancer effect by inhibiting myeloid-derived suppressor cell differentiation in the spleen of mice through down-regulating granulocyte colony stimulating factor

OBJECTIVES

To investigate the mechanism of Xuanhusuo powder (XHSP) inhibiting the differentiation of spleen myeloid-derived suppressor cells (MDSCs) in breast cancer mice.

METHODS

Forty-eight BALB/c female mice aged 4-5 weeks were selected, 6 of them were in normal control group, while others were in tumor-bearing models established by orthotopic injection of 4T1 cells into the subcutaneous fat pad of the second pair of left mammary glands. The tumor-bearing mice were divided into granulocyte colony stimulating factor (G-CSF) control group, G-CSF knock-down group, model control group, XHSP small dose group, XHSP medium dose group, XHSP high dose group, and cyclophosphamide (CTX) group, with 6 mice in each group. G-CSF control group and G-CSF knock-down group were constructed by stably transfecting 4T1 cells established by shRNA lentivirus combined with puromycin selection. 48 h after the model was established, XHSP small, medium, high dose group were given 2, 4, 8 g·kg－1·d－1 intragastric administration once a day, respectively. CTX was given 30 mg/kg by intraperitoneal injection, once every other day. The other groups were given an equal volume of 0.5% hydroxymethylcellulose sodium. The drugs in each group were continuously administered for 25 d. Histological changes in spleen were observed by HE staining, the proportion of MDSCs subsets in the spleen were detected by flow cytometry, the co-expression of CD11b and Ly6G in the spleen was detected by immunofluorescence, and the concentration of G-CSF in peripheral blood was detected by ELISA. The spleen of tumor-bearing mice was co-cultured with 4T1 stably transfected cell lines in vitro, treated with XHSP (30 μg/mL) for 24 h, and the co-expression of CD11b and Ly6G in the spleen was detected by immunofluorescence. 4T1 cells were treated by XHSP (10, 30, 100 μg/mL) for 12 h. The mRNA level of G-CSF was detected by realtime RT-PCR.

RESULTS

Compared with normal mice, the red pulp of the spleen in tumor-bearing mice was widened with megakaryocyte infiltration. The proportion of spleen polymorphonucleocyte-like MDSCs (PMN-MDSCs) was significantly increased (P<0.01) and the co-expression of CD11b and Ly6G was increased, and the concentration of G-CSF in peripheral blood was significantly increased (P<0.01). However, XHSP could significantly reduce the proportion of PMN-MDSCs (P<0.05) and the co-expression of CD11b and Ly6G in the spleen, down-regulate the mRNA level of G-CSF in 4T1 cells (P<0.01). The concentration of G-CSF in peripheral blood of tumor-bearing mice also decreased (P<0.05) and tumor volume was reduced and splenomegaly was improved (all P<0.05).

CONCLUSIONS

XHSP may play an anti-breast cancer role by down-regulating G-CSF, negatively regulating the differentiation of MDSCs, and reconstruct the spleen myeloid microenvironment.

Genetic profiling of different phenotypic subsets of breast cancer stem cells (BCSCs) in breast cancer patients

BACKGROUND

Breast cancer stem cells (BCSCs) have a crucial role in breast carcinogenesis, development, and progression. The aim of the current study is to characterize the BCSCs through the genetic profiling of different BCSCs phenotypic subsets to determine their related genetic pathways.

METHODS

Fresh tumor tissue samples were obtained from 31 breast cancer (BC) patients for (1) Mammosphere culture. (2) Magnetic separation of the BCSCs subsets using CD24, CD44, and CD326 Microbeads. (3) Flow cytometry (FCM) assay using CD44, CD24, and EpCAM. (4) RT-PCR profiler Arrays using stem cell (SC) panel of 84 genes for four group of cells (1) CD44⁺/CD24^-/EpCAM^- BCSCs, (2) CD44⁺/CD24^- /EpCAM⁺ BCSCs, (3) mammospheres, and (4) normal breast tissues.

RESULTS

The BCSCs (CD44⁺/CD24^-/EpCAM^-) showed significant downregulation in 13 genes and upregulation in 15, where the CD44, GJB1 and GDF3 showed the maximal expression (P = 0.001, P = 0.003 and P = 0.007); respectively). The CD44⁺/CD24^-/EpCAM⁺ BCSCs showed significant upregulation in 28 genes, where the CD44, GDF3, and GJB1 showed maximal expression (P < 0.001, P = 0.001 and P = 0.003; respectively). The mammospheres showed significant downregulation in 9 genes and a significant upregulation in 35 genes. The maximal overexpression was observed in GJB1 and FGF2 (P = 0.001, P = 0.001; respectively). The genes which achieved significant overexpression in all SC subsets were CD44, COL9A1, FGF1, FGF2, GDF3, GJA1, GJB1, GJB2, HSPA9, and KRT15. While significant downregulation in BMP2, BMP3, EP300, and KAT8. The genes which were differentially expressed by the mammospheres compared to the other BCSC subsets were CCND2, FGF3, CD4, WNT1, KAT2A, NUMB, ACAN, COL2A1, TUBB3, ASCL2, FOXA2, ISL1, DTX1, and DVL1.

CONCLUSION

BCSCs have specific molecular profiles that differ according to their phenotypes which could affect patients' prognosis and outcome.

Bone morphogenetic proteins, activins, and growth and differentiation factors in tumor immunology and immunotherapy resistance

The TGF-β superfamily is a group of secreted polypeptides with key roles in exerting and regulating a variety of physiologic effects, especially those related to cell signaling, growth, development, and differentiation. Although its central member, TGF-β, has been extensively reviewed, other members of the family-namely bone morphogenetic proteins (BMPs), activins, and growth and differentiation factors (GDFs)-have not been as thoroughly investigated. Moreover, although the specific roles of TGF-β signaling in cancer immunology and immunotherapy resistance have been extensively reported, little is known of the roles of BMPs, activins, and GDFs in these domains. This review focuses on how these superfamily members influence key immune cells in cancer progression and resistance to treatment.

COVID-19 and the role of cytokines in this disease

Studies have shown that SARS-CoV-2 has the ability to activate and mature proinflammatory cytokines in the body. Cytokine markers are a group of polypeptide signalling molecules that can induce and regulate many cellular biological processes by stimulating cell receptors at the surface. SARS-CoV-2 has been shown to be associated with activation of innate immunity, and an increase in neutrophils, mononuclear phagocytes, and natural killer cells has been observed, as well as a decrease in T cells including CD4+ and CD8. It is noteworthy that during the SARS-CoV-2 infection, an increase in the secretion or production of IL-6 and IL-8 is seen in COVID-19 patients along with a decrease in CD4+ and CD8+ and T cells in general. SARS-CoV-2 has been shown to significantly increase Th2, Th1/Th17 cells and antibody production in the body of patients with COVID-19. Specific immune profiles of SARS-CoV-2 infection can lead to secondary infections and dysfunction of various organs in the body. It has been shown that Interleukins (such as IL-1, IL-4, IL-6, IL-7, IL-10, IL-12, IL-17, and IL-18), IFN-γ, TNF-α,TGF-β and NF-κB play major roles in the body's inflammatory response to SARS-CoV-2 infection. The most important goal of this review is to study the role of inflammatory cytokines in COVID-19.

Bone Morphogenetic Protein Signaling in Cancer; Some Topics in the Recent 10 Years

Bone morphogenetic proteins (BMPs), members of the transforming growth factor-β (TGF-β) family, are multifunctional cytokines. BMPs have a broad range of functions, and abnormalities in BMP signaling pathways are involved in cancer progression. BMPs activate the proliferation of certain cancer cells. Malignant phenotypes of cancer cells, such as increased motility, invasiveness, and stemness, are enhanced by BMPs. Simultaneously, BMPs act on various cellular components and regulate angiogenesis in the tumor microenvironment. Thus, BMPs function as pro-tumorigenic factors in various types of cancer. However, similar to TGF-β, which shows both positive and negative effects on tumorigenesis, BMPs also act as tumor suppressors in other types of cancers. In this article, we review important findings published in the recent decade and summarize the pro-oncogenic functions of BMPs and their underlying mechanisms. The current status of BMP-targeted therapies for cancers is also discussed.

Targeting Stress Erythropoiesis Pathways in Cancer

Cancer-related anemia (CRA) is a common multifactorial disorder that adversely affects the quality of life and overall prognosis in patients with cancer. Safety concerns associated with the most common CRA treatment options, including intravenous iron therapy and erythropoietic-stimulating agents, have often resulted in no or suboptimal anemia management for many cancer patients. Chronic anemia creates a vital need to restore normal erythropoietic output and therefore activates the mechanisms of stress erythropoiesis (SE). A growing body of evidence demonstrates that bone morphogenetic protein 4 (BMP4) signaling, along with glucocorticoids, erythropoietin, stem cell factor, growth differentiation factor 15 (GDF15) and hypoxia-inducible factors, plays a pivotal role in SE. Nevertheless, a chronic state of SE may lead to ineffective erythropoiesis, characterized by the expansion of erythroid progenitor pool, that largely fails to differentiate and give rise to mature red blood cells, further aggravating CRA. In this review, we summarize the current state of knowledge on the emerging roles for stress erythroid progenitors and activated SE pathways in tumor progression, highlighting the urgent need to suppress ineffective erythropoiesis in cancer patients and develop an optimal treatment strategy as well as a personalized approach to CRA management.

Activation of Host-NLRP3 Inflammasome in Myeloid Cells Dictates Response to Anti-PD-1 Therapy in Metastatic Breast Cancers

Tumor-associated inflammation leads to dysregulated cytokine production that promotes tumor immune evasion and anti-tumor immunity dysfunction. In advanced stage breast cancer, the proinflammatory cytokine IL-1β is overexpressed due to large proportions of activated myeloid cells in the tumor microenvironment (TME). Here, we demonstrate the role of the host nucleotide-binding domain, leucine-rich containing family, pyrin domain-containing 3 (NLRP3) inflammasome in metastatic breast cancer. In vitro, we show that stimulation of THP-1 cells with conditioned media collected from MDA-MB-468 cells induced NLRP3 activation and increased Pdcd1l1 expression. In vivo, mice deficient in NLRP3 orthotopically implanted with metastatic breast cancer cell line (E0771) showed significant reduction in tumor growth (p < 0.05) and increased survival (p < 0.01). Inhibition of NLRP3 with the small molecule OLT1177® reduced expression of Pdcd1l1 (p < 0.001), Casp1 (p < 0.01) and Il1b (p < 0.01) in primary tumors. Furthermore, tumor-bearing mice receiving OLT1177® showed reduced infiltration of myeloid-derived suppressor cells (MDSCs) (p < 0.001) and increased CD8+ T cells (p < 0.05) and NK cells (p < 0.05) in the TME. NLRP3 inhibition in addition to anti-PD-1 treatment significantly reduced tumor growth from the monotherapies (p < 0.05). These data define NLRP3 activation as a key driver of immune suppression in metastatic breast cancers. Furthermore, this study suggests NLRP3 as a valid target to increase efficacy of immunotherapy with checkpoint inhibitor in metastatic breast cancers.

Inhibiting ALK2/ALK3 Signaling to Differentiate and Chemo-Sensitize Medulloblastoma

Simple Summary

Many cancers re-emerge after treatment, despite the sensitivity of the bulk of tumor cells to treatments. This observation has led to the ‘cancer stem cell’ (CSCs) hypothesis, stating that a subpopulation of cancer cells survive therapy and lead to tumor relapse. However, the lack of universal markers to target CSCs is the main constraint to fully eradicate the CSC pool. Differentiation therapy (DT) might in principle suppress tumorigenesis through conversion of undifferentiated cancer cells of high malignancy into differentiated cells of low tumorigenic potential. Here, we provide evidence that CSCs of medulloblastoma can be forced to resume their differentiation potential by inhibiting the BMP4–ALK2/3 axis, providing a new entry point for medulloblastoma treatment.

Abstract

Background: Medulloblastoma (MB) is a malignant pediatric brain tumor, and it represents the leading cause of death related to cancer in childhood. New perspectives for therapeutic development have emerged with the identification of cancer stem cells (CSCs) displaying tumor initiating capability and chemoresistance. However, the mechanisms responsible for CSCs maintenance are poorly understood. The lack of a universal marker signature represents the main constraints to identify and isolate CSCs within the tumor. Methods: To identify signaling pathways promoting CSC maintenance in MB, we combined tumorsphere assays with targeted neurogenesis PCR pathway arrays. Results: We showed a consistent induction of signaling pathways regulating pluripotency of CSCs in all the screened MB cells. BMP4 signaling was consistently enriched in all tumorsphere(s) independently of their specific stem-cell marker profile. The octamer-binding transcription factor 4 (OCT4), an important regulator of embryonic pluripotency, enhanced CSC maintenance in MBs by inducing the BMP4 signaling pathway. Consistently, inhibition of BMP4 signaling with LDN-193189 reduced stem-cell traits and promoted cell differentiation. Conclusions: Our work suggests that interfering with the BMP4 signaling pathway impaired the maintenance of the CSC pool by promoting cell differentiation. Hence, differentiation therapy might represent an innovative therapeutic to improve the current standard of care in MB patients.

Cancer-cell-intrinsic mechanisms regulate MDSCs through cytokine networks

Immunotherapy has shifted the paradigm of cancer treatment. However, the majority of cancer patients display de novo or acquired resistance to immunotherapy. One of the main mechanisms of immunotherapy resistance is the immunosuppressive microenvironment dominated by the myeloid-derived suppressor cells (MDSCs). Emerging evidence demonstrates that genetic or epigenetic aberrations in cancer cells shape the accumulation and activation of MDSCs. Understanding this genotype-immunophenotype relationship is critical to the rational design of combination immunotherapy. Here, we review the mechanisms of how molecular changes in cancer cells induce recruitment and reprogram the function of tumor-infiltrating myeloid cells, particularly MDSCs. Tumor-infiltrating MDSCs elicit various pro-tumor functions to promote tumor cell fitness, immune evasion, angiogenesis, tissue remodeling, and metastasis. Through understanding the genotype-immunophenotype relationship between neoplastic cells and MDSCs, new approaches can be developed to tailor current immunotherapy strategies to improve cancer patient outcomes.

Therapeutic Targets in Diffuse Midline Gliomas-An Emerging Landscape

Simple Summary

Diffuse midline gliomas (DMGs) remain one of the most devastating childhood brain tumour types, for which there is currently no known cure. In this review we provide a summary of the existing knowledge of the molecular mechanisms underlying the pathogenesis of this disease, highlighting current analyses and novel treatment propositions. Together, the accumulation of these data will aid in the understanding and development of more effective therapeutic options for the treatment of DMGs.

Abstract

Diffuse midline gliomas (DMGs) are invariably fatal pediatric brain tumours that are inherently resistant to conventional therapy. In recent years our understanding of the underlying molecular mechanisms of DMG tumorigenicity has resulted in the identification of novel targets and the development of a range of potential therapies, with multiple agents now being progressed to clinical translation to test their therapeutic efficacy. Here, we provide an overview of the current therapies aimed at epigenetic and mutational drivers, cellular pathway aberrations and tumor microenvironment mechanisms in DMGs in order to aid therapy development and facilitate a holistic approach to patient treatment.

Beyond immunosuppressive effects: dual roles of myeloid-derived suppressor cells in bone-related diseases

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells (IMCs) with immunosuppressive functions, whereas IMCs originally differentiate into granulocytes, macrophages, and dendritic cells (DCs) to participate in innate immunity under steady-state conditions. At present, difficulties remain in identifying MDSCs due to lacking of specific biomarkers. To make identification of MDSCs accurately, it also needs to be determined whether having immunosuppressive functions. MDSCs play crucial roles in anti-tumor, angiogenesis, and metastasis. Meanwhile, MDSCs could make close interaction with osteoclasts, osteoblasts, chondrocytes, and other stromal cells within microenvironment of bone and joint, and thereby contributing to poor prognosis of bone-related diseases such as cancer-related bone metastasis, osteosarcoma (OS), rheumatoid arthritis (RA), osteoarthritis (OA), and orthopedic trauma. In addition, MDSCs have been shown to participate in the procedure of bone repair. In this review, we have summarized the function of MDSCs in cancer-related bone metastasis, the interaction with stromal cells within the bone microenvironment as well as joint microenvironment, and the critical role of MDSCs in bone repair. Besides, the promising value of MDSCs in the treatment for bone-related diseases is also well discussed.

Mammary tumour cells remodel the bone marrow vascular microenvironment to support metastasis

Bone marrow is a preferred metastatic site for multiple solid tumours and is associated with poor prognosis and significant morbidity. Accumulating evidence indicates that cancer cells colonise specialised niches within the bone marrow to support their long-term propagation, but the precise location and mechanisms that mediate niche interactions are unknown. Using breast cancer as a model of solid tumour metastasis to the bone marrow, we applied large-scale quantitative three-dimensional imaging to characterise temporal changes in the bone marrow microenvironment during disease progression. We show that mouse mammary tumour cells preferentially home to a pre-existing metaphyseal domain enriched for type H vessels. Metastatic lesion outgrowth rapidly remodelled the local vasculature through extensive sprouting to establish a tumour-supportive microenvironment. The evolution of this tumour microenvironment reflects direct remodelling of the vascular endothelium through tumour-derived granulocyte-colony stimulating factor (G-CSF) in a hematopoietic cell-independent manner. Therapeutic targeting of the metastatic niche by blocking G-CSF receptor inhibited pathological blood vessel remodelling and reduced bone metastasis burden. These findings elucidate a mechanism of 'host' microenvironment hijacking by mammary tumour cells to subvert the local microvasculature to form a specialised, pro-tumorigenic niche.

Selectively targeting myeloid-derived suppressor cells through TRAIL receptor 2 to enhance the efficacy of CAR T cell therapy for treatment of breast cancer

BACKGROUND

Successful targeting of solid tumors such as breast cancer (BC) using chimeric antigen receptor (CAR) T cells has proven challenging, largely attributed to the immunosuppressive tumor microenvironment (TME). Myeloid-derived suppressor cells (MDSCs) inhibit CAR T cell function and persistence within the breast TME. To overcome this challenge, we have developed CAR T cells targeting tumor-associated mucin 1 (MUC1) with a novel chimeric costimulatory receptor that targets tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TR2) expressed on MDSCs.

METHODS

The function of the TR2.41BB costimulatory receptor was assessed by exposing non-transduced (NT) and TR2.41BB transduced T cells to recombinant TR2, after which nuclear translocation of NFκB was measured by ELISA and western blot. The cytolytic activity of CAR.MUC1/TR2.41BB T cells was measured in a 5-hour cytotoxicity assay using MUC1+ tumor cells as targets in the presence or absence of MDSCs. In vivo antitumor activity was assessed using MDSC-enriched tumor-bearing mice treated with CAR T cells with or without TR2.41BB.

RESULTS

Nuclear translocation of NFκB in response to recombinant TR2 was detected only in TR2.41BB T cells. The presence of MDSCs diminished the cytotoxic potential of CAR.MUC1 T cells against MUC1+ BC cell lines by 25%. However, TR2.41BB expression on CAR.MUC1 T cells induced MDSC apoptosis, thereby restoring the cytotoxic activity of CAR.MUC1 T cells against MUC1+ BC lines. The presence of MDSCs resulted in an approximately twofold increase in tumor growth due to enhanced angiogenesis and fibroblast accumulation compared with mice with tumor alone. Treatment of these MDSC-enriched tumors with CAR.MUC1.TR2.41BB T cells led to superior tumor cell killing and significant reduction in tumor growth (24.54±8.55 mm³) compared with CAR.MUC1 (469.79±81.46 mm³) or TR2.41BB (434.86±64.25 mm³) T cells alone. CAR.MUC1.TR2.41BB T cells also demonstrated improved T cell proliferation and persistence at the tumor site, thereby preventing metastases. We observed similar results using CAR.HER2.TR2.41BB T cells in a HER2+ BC model.

CONCLUSIONS

Our findings demonstrate that CAR T cells that coexpress the TR2.4-1BB receptor exhibit superior antitumor potential against breast tumors containing immunosuppressive and tumor promoting MDSCs, resulting in TME remodeling and improved T cell proliferation at the tumor site.

Immunomodulatory effects of G-CSF in cancer: Therapeutic implications

Numerous preclinical studies have reported a pro-tumour role for granulocyte colony-stimulating factor (G-CSF) that is predominantly mediated by neutrophils and MDSCs, the major G-CSF receptor expressing populations. In the presence of G-CSF (either tumour-derived or exogenous) these myeloid populations commonly exhibit a T cell suppressive phenotype. However, the direct effects of this cytokine on other immune lineages, such as T and NK cells, are not as well established. Herein we discuss the most recent data relating to the effect of G-CSF on the major immune populations, exclusively in the context of cancer. Recent publications have drawn attention to the other tumour-promoting effects of G-CSF on myeloid cells, including NETosis, promotion of cancer stemness and skewed differentiation of bone marrow progenitors towards myelopoiesis. Although G-CSF is safely and commonly used as a supportive therapy to prevent or treat chemotherapy-associated neutropenia in cancer patients, we also discuss the potential impacts of G-CSF on other anti-cancer treatments. Importantly, considerations for immune checkpoint blockade are highlighted, as many publications report a T cell suppressive effect of G-CSF that may diminish the effectiveness of this immunotherapy.

BMP4 enhances anoikis resistance and chemoresistance of breast cancer cells through canonical BMP signaling

Bone morphogenetic proteins (BMPs) regulate cell fate during development and mediate cancer progression. In this study, we investigated the role of BMP4 in proliferation, anoikis resistance, metastatic migration, and drug resistance of breast cancer cells. We utilized breast cancer cell lines and clinical samples representing different subtypes to understand the functional effect of BMP4 on breast cancer. The BMP pathway was inhibited with the small molecule inhibitor LDN193189 hydrochloride (LDN). BMP4 signaling enhanced the expression of stem cell genes CD44, ALDH1A3, anti-apoptotic gene BCL2 and promoted anoikis resistance in MDA-MB-231 breast cancer cells. BMP4 enhanced self-renewal and chemoresistance in MDA-MB-231 by upregulating Notch signaling while LDN treatment abrogated anoikis resistance and proliferation of anoikis resistant breast cancer cells in the osteogenic microenvironment. Conversely, BMP4 downregulated proliferation, colony-forming ability, and suppressed anoikis resistance in MCF7 and SkBR3 cells, while LDN treatment promoted tumor spheroid formation and growth. These findings indicate that BMP4 has a context-dependent role in breast cancer. Further, our data with MDA-MB-231 cells representing triple-negative breast cancer suggest that BMP inhibition might impair its metastatic spread and colonization.

Histamine in cancer immunology and immunotherapy. Current status and new perspectives

Cancer is the second leading cause of death globally and its incidence and mortality are rapidly increasing worldwide. The dynamic interaction of immune cells and tumor cells determines the clinical outcome of cancer. Immunotherapy comes to the forefront of cancer treatments, resulting in impressive and durable responses but only in a fraction of patients. Thus, understanding the characteristics and profiles of immune cells in the tumor microenvironment (TME) is a necessary step to move forward in the design of new immunomodulatory strategies that can boost the immune system to fight cancer. Histamine produces a complex and fine-tuned regulation of the phenotype and functions of the different immune cells, participating in multiple regulatory responses of the innate and adaptive immunity. Considering the important actions of histamine-producing immune cells in the TME, in this review we first address the most important immunomodulatory roles of histamine and histamine receptors in the context of cancer development and progression. In addition, this review highlights the current progress and foundational developments in the field of cancer immunotherapy in combination with histamine and pharmacological compounds targeting histamine receptors.

Opposing Effects of Granulocyte Colony-Stimulating Factor on the Initiation and Progression of Breast Cancer Bone Metastases

Granulocyte colony stimulating factor (G-CSF), an essential cytokine regulating granulopoiesis, is expressed in a substantial proportion of breast cancers, and it has been implicated in cancer progression. Here, we examined effects of G-CSF on the development of bone metastases of breast cancer using immunocompetent mouse models. The expression of CXC chemokine ligand 12 (CXCL12) in bone marrow stromal cells, which plays a critical role in the maintenance of hematopoietic stem cells and also in cancer cell homing to bone, was markedly decreased in mice treated with G-CSF. Flow cytometric analysis revealed that pretreatment of mice with G-CSF reduced the number of bone-homing cancer cells. G-CSF also increased the population of myeloid-derived suppressor cells (MDSCs) in bone marrow. Depletion of MDSCs using anti-Gr-1 antibody treatment significantly decreased the metastatic tumor burden in bone. The overall effects of G-CSF on bone metastases were finally examined using two different treatment protocols. When mice were treated with G-CSF prior to the tumor cell inoculation, G-CSF did not change bone metastatic-tumor burden. In contrast, when G-CSF treatment was started after the tumor cells had homed to bone, G-CSF significantly accelerated bone metastases formation. These results suggest that G-CSF suppressed cancer cell homing to bone by downregulating CXCL12 expression in bone marrow stromal cells, whereas G-CSF stimulated the progression of bone metastases at least in part by MDSC-mediated mechanisms. IMPLICATIONS: G-CSF had opposing effects on the initiation and progression of bone metastases of breast cancer and the balance may regulate the metastatic tumor burden.

Predicting Agents That Can Overcome 5-FU Resistance in Colorectal Cancers via Pharmacogenomic Analysis

5-Fluorouracil (5-FU) is one of several chemotherapeutic agents in clinical use as a standard of care to treat colorectal cancers (CRCs). As an antimetabolite, 5-FU inhibits thymidylate synthase to disrupt the synthesis and repair of DNA and RNA. However, only a small proportion of patients benefit from 5-FU treatment due to the development of drug resistance. This study applied pharmacogenomic analysis using two public resources, the Genomics of Drug Sensitivity in Cancer (GDSC) and the Connectivity Map, to predict agents overcoming 5-FU resistance in CRC cells based on their genetic background or gene expression profile. Based on the genetic status of adenomatous polyposis coli (APC), the most frequent mutated gene found in CRC, we found that combining a MEK inhibitor with 5-FU exhibited synergism effects on CRC cells with APC truncations. While considering the gene expression in 5-FU resistant cells, we demonstrated that targeting ROCK is a potential avenue to restore 5-FU response to resistant cells with wild-type APC background. Our results reveal MEK signaling plays a pivotal role in loss-of-function, APC-mediated 5-FU resistance, and ROCK activation serves as a signature in APC-independent 5-FU resistance. Through the use of these available database resources, we highlight possible approaches to predict potential drugs for combinatorial therapy for patients developing resistance to 5-FU treatment.

Osteoimmuno-Oncology: Therapeutic Opportunities for Targeting Immune Cells in Bone Metastasis

Immunotherapies provide a potential treatment option for currently incurable bone metastases. Bone marrow is an important secondary lymphoid organ with a unique immune contexture. Even at non-disease state immune cells and bone cells interact with each other, bone cells supporting the development of immune cells and immune cells regulating bone turnover. In cancer, tumor cells interfere with this homeostatic process starting from formation of pre-metastatic niche and later supporting growth of bone metastases. In this review, we introduce a novel concept osteoimmuno-oncology (OIO), which refers to interactions between bone, immune and tumor cells in bone metastatic microenvironment. We also discuss therapeutic opportunities of targeting immune cells in bone metastases, and associated efficacy and safety concerns.

Role of immune regulatory cells in breast cancer: Foe or friend?

Breast cancer (BC) is the most common cancer among women between the ages of 20 and 50, affecting more than 2.1 million people and causing the annual death of more than 627,000 women worldwide. Based on the available knowledge, the immune system and its components are involved in the pathogenesis of several malignancies, including BC. Cancer immunobiology suggests that immune cells can play a dual role and induce anti-tumor or immunosuppressive responses, depending on the tumor microenvironment (TME) signals. The most important effector immune cells with anti-tumor properties are natural killer (NK) cells, B, and T lymphocytes. On the other hand, immune and non-immune cells with regulatory/inhibitory phenotype, including regulatory T cells (Tregs), regulatory B cells (Bregs), tolerogenic dendritic cells (tDCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), mesenchymal stem cells (MSCs), and regulatory natural killer cells (NKregs), can promote the growth and development of tumor cells by inhibiting anti-tumor responses, inducing angiogenesis and metastasis, as well as the expression of inhibitory molecules and suppressor mediators of the immune system. However, due to the complexity of the interaction and the modification in the immune cells' phenotype and the networking of the immune responses, the exact mechanism of action of the immunosuppressive and regulatory cells is not yet fully understood. This review article reviews the immune responses involved in BC as well as the role of regulatory and inhibitory cells in the pathogenesis of the disease. Finally, therapeutic approaches based on inhibition of immunosuppressive responses derived from regulatory cells are discussed.

Contrasting roles for BMP-4 and ventromorphins (BMP agonists) in TGFβ-induced lens EMT

Transforming growth factor beta (TGFβ) and bone morphogenetic protein (BMP) signaling play opposing roles in epithelial-mesenchymal transition (EMT) of lens epithelial cells, a cellular process integral to the pathogenesis of fibrotic cataract. We previously showed that BMP-7-induced Smad1/5 signaling blocks TGFβ-induced Smad2/3-signaling and EMT in rat lens epithelial cell explants. To further explore the antagonistic role of BMPs on TGFβ-signaling, we tested the capability of BMP-4 or newly described BMP agonists, ventromorphins, in blocking TGFβ-induced lens EMT. Primary rat lens epithelial explants were treated with exogenous TGFβ2 alone, or in combination with BMP-4 or ventromorphins. Treatment with TGFβ2 induced lens epithelial cells to undergo EMT and transdifferentiate into myofibroblastic cells with upregulated α-SMA and nuclear translocation of Smad2/3 immunofluorescence. BMP-4 was able to suppress this EMT without blocking TGFβ2-nuclear translocation of Smad2/3. In contrast, the BMP agonists, ventromorphins, were unable to block TGFβ2-induced EMT, despite a transient and early ability to significantly reduce TGFβ2-induced nuclear translocation of Smad2/3. This intriguing disparity highlights new complexities in the responsiveness of the lens to differing BMP-related signaling. Further research is required to better understand the antagonistic relationship between TGFβ and BMPs in lens EMT leading to cataract.

G-CSF in tumors: Aggressiveness, tumor microenvironment and immune cell regulation

Granulocyte colony-stimulating factor (G-CSF) is a cytokine most well-known for maturation and mobilization of bone marrow neutrophils. Although it is used therapeutically to treat chemotherapy induced neutropenia, it is also highly expressed in some tumors. Case reports suggest that tumors expressing high levels of G-CSF are aggressive, more difficult to treat, and present with poor prognosis and high mortality rates. Research on this topic suggests that G-CSF has tumor-promoting effects on both tumor cells and the tumor microenvironment. G-CSF has a direct effect on tumor cells to promote tumor stem cell longevity and overall tumor cell proliferation and migration. Additionally, it may promote pro-tumorigenic immune cell phenotypes such as M2 macrophages, myeloid-derived suppressor cells, and regulatory T cells. Overall, the literature suggests a plethora of pro-tumorigenic activity that should be balanced with the therapeutic use. In this review, we present an overview of the multiple complex roles of G-CSF and G-CSFR in tumors and their microenvironment and discuss how clinical advances and strategies may open new therapeutic avenues.

Role of the BMP6 protein in breast cancer and other types of cancer

The BMP6 protein (Bone Morphogenetic Protein 6) is part of the superfamily of transforming growth factor-beta (TGF-β) ligands, participates in iron homeostasis, inhibits invasion by increasing adhesions and cell-cell type interactions and induces angiogenesis directly on vascular endothelial cells. BMP6 is coded by a tumor suppressor gene whose subexpression is related to the development and cancer progression; during neoplastic processes, methylation is the main mechanism by which gene silencing occurs. This work presents a review on the role of BMP6 protein in breast cancer (BC) and other types of cancer. The studies carried out to date suggest the participation of the BMP6 protein in the epithelial-mesenchymal transition (EMT) phenotype, cell growth and proliferation; however, these processes are affected in a variable way in the different types of cancer, the methylated CpG sites in BMP6 gene promoter, as well as the interaction with other proteins could be the cause of such variation.

The Role and Therapeutic Potential of NF-kappa-B Pathway in Severe COVID-19 Patients

Coronavirus disease 2019 (COVID-19) pandemic has affected health care systems worldwide. Severe presentations of COVID-19 such as severe pneumonia and acute respiratory distress syndrome (ARDS) have been associated with the post-viral activation and release of cytokine/chemokines which leads to a "cytokine storm" causing inflammatory response and destruction, mainly affecting the lungs. COVID-19 activation of transcription factor, NF-kappa B (NF-κB) in various cells such as macrophages of lung, liver, kidney, central nervous system, gastrointestinal system and cardiovascular system leads to production of IL-1, IL-2, IL-6, IL-12, TNF-α, LT-α, LT-β, GM-CSF, and various chemokines. The sensitised NF-κB in elderly and in patients with metabolic syndrome makes this set of population susceptible to COVID-19 and their worse complications, including higher mortality. Immunomodulation at the level of NF-κB activation and inhibitors of NF-κB (IκB) degradation along with TNF-α inhibition will potentially result in a reduction in the cytokine storm and alleviate the severity of COVID-19. Inhibition of NF-κB pathway has a potential therapeutic role in alleviating the severe form of COVID-19.

Inhibition of the BMP Signaling Pathway Ameliorated Established Clinical Symptoms of Experimental Autoimmune Encephalomyelitis

Bone morphogenetic proteins (BMPs) are secreted growth factors that belong to the transforming growth factor beta superfamily. BMPs have been implicated in physiological processes, but they are also involved in many pathological conditions. Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS); however, its etiology remains elusive. Some evidence points to BMPs as important players in the pathogenesis of inflammatory and autoimmune disorders. In the present work, we studied the expression of BMP2, BMP4, BMP5, BMP6, BMP7, BMP type II receptor, and noggin in the immune system during different phases of experimental autoimmune encephalomyelitis (EAE). Major changes in the expression of BMPs took place in the initial phases of EAE. Indeed, those changes mainly affected BMP6 (whose expression was abrogated), BMP2, and BMP7 (whose expression was increased). In addition, we showed that in vivo inhibition of the BMP signaling pathway with small molecules ameliorated the already established clinical symptoms of EAE, as well as the CNS histopathological features. At the immune level, we observed an expansion of plasmacytoid dendritic cells (pDCs) in mice treated with small molecules that inhibit the BMP signaling pathway. pDCs could play an important role in promoting the expansion of antigen-specific regulatory T cells. Altogether, our data suggest a role for BMPs in early immune events that take place in myelin oligodendrocyte glycoprotein (MOG)-induced EAE. In addition, the clinical outcome of the disease was improved when the BMP signaling pathway was inhibited in mice that presented established EAE symptoms.

Splenic Hematopoietic and Stromal Cells in Cancer Progression

Tumor-derived secretory factors orchestrate splenic hematopoietic and stromal cells to fuel metastasis. The spleen acts as a reservoir site for hematopoietic stem and progenitor cells, which are rapidly exploited as myeloid-derived suppressor cells at the cost of tumor-reactive lymphoid cells. Splenic erythroid progenitor cells and mesenchymal stromal cells contribute directly and indirectly to both tumor immune escape and the metastatic cascade. Animal models provide valuable mechanistic insights, but their translation to a clinical setting highlights specific challenges and open issues. In this review, we envision the exploitation of the spleen as a source for novel biomarkers and therapeutic approaches.

Multidirectional Strategies for Targeted Delivery of Oncolytic Viruses by Tumor Infiltrating Immune Cells

Oncolytic virus (OV) immunotherapy has demonstrated to be a promising approach in cancer treatment due to tumor-specific oncolysis. However, their clinical use so far has been largely limited due to the lack of suitable delivery strategies with high efficacy. Direct 'intratumoral' injection is the way to cross the hurdles of systemic toxicity, while providing local effects. Progress in this field has enabled the development of alternative way using 'systemic' oncolytic virotherapy for producing better results. One major potential roadblock to systemic OV delivery is the low virus persistence in the face of hostile immune system. The delivery challenge is even greater when attempting to target the oncolytic viruses into the entire tumor mass, where not all tumor cells are equally exposed to exactly the same microenvironment. The microenvironment of many tumors is known to be massively infiltrated with various types of leucocytes in both primary and metastatic sites. Interestingly, this intratumoral immune cell heterogeneity exhibits a degree of organized distribution inside the tumor bed as evidenced, for example, by the hypoxic tumor microenviroment where predominantly recruits tumor-associated macrophages. Although in vivo OV delivery seems complicated and challenging, recent results are encouraging for decreasing the limitations of systemically administered oncolytic viruses and an improved efficiency of oncolytic viral therapy in targeting cancerous tissues in vitro. Here, we review the latest developments of carrier cell-based oncolytic virus delivery using tumor-infiltrating immune cells with a focus on the main features of each cellular vehicle.

Bone metastasis is associated with acquisition of mesenchymal phenotype and immune suppression in a model of spontaneous breast cancer metastasis

The most common site of breast cancer metastasis is the bone, occurring in approximately 70% of patients with advanced disease. Bone metastasis is associated with severe morbidities and high mortality. Therefore, deeper understanding of the mechanisms that enable bone-metastatic relapse are urgently needed. We report the establishment and characterization of a bone-seeking variant of breast cancer cells that spontaneously forms aggressive bone metastases following surgical resection of primary tumor. We characterized the modifications in the immune milieu during early and late stages of metastatic relapse and found that the formation of bone metastases is associated with systemic changes, as well as modifications of the bone microenvironment towards an immune suppressive milieu. Furthermore, we characterized the intrinsic changes in breast cancer cells that facilitate bone-tropism and found that they acquire mesenchymal and osteomimetic features. This model provides a clinically relevant platform to study the functional interactions between breast cancer cells and the bone microenvironment, in an effort to identify novel targets for intervention.

Role of Tumor-Associated Myeloid Cells in Breast Cancer

Stromal immune cells constitute the tumor microenvironment. These immune cell subsets include myeloid cells, the so-called tumor-associated myeloid cells (TAMCs), which are of two types: tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs). Breast tumors, particularly those in human epidermal growth factor receptor 2 (HER-2)-positive breast cancer and triple-negative breast cancer, are solid tumors containing immune cell stroma. TAMCs drive breast cancer progression via immune mediated, nonimmune-mediated, and metabolic interactions, thus serving as a potential therapeutic target for breast cancer. TAMC-associated breast cancer treatment approaches potentially involve the inhibition of TAM recruitment, modulation of TAM polarization/differentiation, reduction of TAM products, elimination of MDSCs, and reduction of MDSC products. Furthermore, TAMCs can enhance or restore immune responses during cancer immunotherapy. This review describes the role of TAMs and MDSCs in breast cancer and elucidates the clinical implications of TAMs and MDSCs as potential targets for breast cancer treatment.

BMP4 promotes the metastasis of gastric cancer by inducing epithelial-mesenchymal transition via ID1

Epithelial-mesenchymal transition (EMT) is a crucial process for cancer cells to acquire metastatic potential, which primarily causes death in gastric cancer (GC) patients. Bone morphogenetic protein 4 (BMP4) is a member of the TGF-β family that plays an indispensable role in human cancers. However, little is known about its roles in GC metastasis. In this study, BMP4 was found to be frequently overexpressed in GC tissues and was correlated with poor patient's prognosis. BMP4 was upregulated in GC cell lines and promoted EMT and metastasis of GC cells both in vitro and in vivo, whereas knockdown of BMP4 significantly inhibited EMT and metastasis of GC cells. Furthermore, the inhibitor of DNA binding 1 (also known as DNA-binding protein inhibitor ID1) was identified as a downstream target of BMP4 using PCR arrays and was upregulated via SMAD1/5/8 phosphorylation. ID1 knockdown attenuated BMP4-induced EMT and invasion in GC cells. Moreover, ID1 overexpression in BMP4 knockdown cells restored the promotion of EMT and cell invasion. In summary, BMP4 induced EMT and promoted GC metastasis by upregulating ID1 expression. Antagonizing BMP4 could be a potential therapeutic strategy for GC metastasis.

Targeting TRAF3IP2, Compared to Rab27, is More Effective in Suppressing the Development and Metastasis of Breast Cancer

Here we investigated the roles of Rab27a, a player in exosome release, and TRAF3IP2, an inflammatory mediator, in development and metastasis of breast cancer (BC) in vivo. Knockdown (KD) of Rab27a (MDA_KDRab27a) or TRAF3IP2 (MDA_KDTRAF3IP2) in triple negative MDA-MB231 cells reduced tumor growth by 70-97% compared to wild-type tumors (MDA_w). While metastasis was detected in MDA_w-injected animals, none was detected in MDA_KDRab27a- or MDA_KDTRAF3IP2-injected animals. Interestingly, micrometastasis was detected only in the MDA_KDRab27a-injected group. In addition to inhibiting tumor growth and metastasis, silencing TRAF3IP2 disrupted inter-cellular inflammatory mediator-mediated communication with mesenchymal stem cells (MSCs) injected into contralateral mammary gland, evidenced by the lack of tumor growth at MSC-injected site. Of translational significance, treatment of pre-formed MDA_w-tumors with a lentiviral-TRAF3IP2-shRNA not only regressed their size, but also prevented metastasis. These results demonstrate that while silencing Rab27a and TRAF3IP2 each inhibited tumor growth and metastasis, silencing TRAF3IP2 is more effective; targeting TRAF3IP2 inhibited tumor formation, regressed preformed tumors, and prevented both macro- and micrometastasis. Silencing TRAF3IP2 also blocked interaction between tumor cells and MSCs injected into the contralateral gland, as evidenced by the lack of tumor formation on MSCs injected site. These results identify TRAF3IP2 as a novel therapeutic target in BC.

Multi-Omics Analysis Reveals the Pan-Cancer Landscape of Bone Morphogenetic Proteins

Background

Bone morphogenetic proteins (BMPs) are widely involved in cancer development. However, a wealth of conflicting data raises the question of whether BMPs serve as oncogenes or as cancer suppressors.

Material/Methods

By integrating multi-omics data across cancers, we comprehensively analyzed the genomic and pharmacogenomic landscape of BMP genes across cancers.

Results

Surprisingly, our data indicate that BMPs are globally downregulated in cancers. Further genetics and epigenetics analyses show that this abnormal expression is driven by copy number variations, especially heterozygous amplification. We next assessed the BMP-associated pathways and demonstrated that they suppress cell cycle and estrogen hormone pathways. Bone morphogenetic protein interacts with 58 compounds, and their dysfunction can induce drug sensitivity.

Conclusions

Our results define the landscape of the BMP family at a systems level and open potential therapeutic opportunities for cancer patients.

Bone morphogenetic proteins mediate crosstalk between cancer cells and the tumour microenvironment at primary tumours and metastases (Review)

Bone morphogenetic proteins (BMP) are pluripotent molecules, co‑ordinating cellular functions from early embryonic and postnatal development to tissue repair, regeneration and homeostasis. They are also involved in tumourigenesis, disease progression and the metastasis of various solid tumours. Emerging evidence has indicated that BMPs are able to promote disease progression and metastasis by orchestrating communication between cancer cells and the surrounding microenvironment. The interactions occur between BMPs and epidermal growth factor receptor, hepatocyte growth factor, fibroblast growth factor, vascular endothelial growth factor and extracellular matrix components. Overall, these interactions co‑ordinate the cellular functions of tumour cells and other types of cell in the tumour to promote the growth of the primary tumour, local invasion, angiogenesis and metastasis, and the establishment and survival of cancer cells in the metastatic niche. Therefore, the present study aimed to provide an informative summary of the involvement of BMPs in the tumour microenvironment.

The role of granulocyte colony‑stimulating factor in breast cancer development: A review

Granulocyte-colony-stimulating factor (G-CSF) is a member of the hematopoietic growth factor family that primarily affects the neutrophil lineage. G-CSF serves as a powerful mobilizer of peripheral blood stem cells and recombinant human G-CSF (rhG-CSF) has been used to treat granulocytopenia and neutropenia after chemotherapy for cancer patients. However, recent studies have found that G-CSF plays an important role in cancer progression. G-CSF expression is increased in different types of cancer cells, such as lung cancer, gastric cancer, colorectal cancer, invasive bladder carcinoma, glioma and breast cancer. However, it is unclear whether treatment with G-CSF has an adverse effect. The current review provides an overview of G-CSF in malignant breast cancer development and the data presented in this review are expected to provide new ideas for cancer therapy.

Permanent Pro-Tumorigenic Shift in Adipose Tissue-Derived Mesenchymal Stromal Cells Induced by Breast Malignancy

During cancer progression, breast tumor cells interact with adjacent adipose tissue, which has been shown to be engaged in cancer aggressiveness. However, the tumor-directed changes in adipose tissue-resident stromal cells affected by the tumor–stroma communication are still poorly understood. The acquired changes might remain in the tissue even after tumor removal and may contribute to tumor relapse. We investigated functional properties (migratory capacity, expression and secretion profile) of mesenchymal stromal cells isolated from healthy (n = 9) and tumor-distant breast adipose tissue (n = 32). Cancer patient-derived mesenchymal stromal cells (MSCs) (MSC-CA) exhibited a significantly disarranged secretion profile and proliferation potential. Co-culture with MDA-MB-231, T47D and JIMT-1, representing different subtypes of breast cancer, was used to analyze the effect of MSCs on proliferation, invasion and tumorigenicity. The MSC-CA enhanced tumorigenicity and altered xenograft composition in immunodeficient mice. Histological analysis revealed collective cell invasion with a specific invasive front of EMT-positive tumor cells as well as invasion of cancer cells to the nerve-surrounding space. This study identifies that adipose tissue-derived mesenchymal stromal cells are primed and permanently altered by tumor presence in breast tissue and have the potential to increase tumor cell invasive ability through the activation of epithelial-to-mesenchymal transition in tumor cells.

Activation of Canonical BMP4-SMAD7 Signaling Suppresses Breast Cancer Metastasis

Metastasis is the major cause of death in patients with cancer; with no therapeutic cure, treatments remain largely palliative. As such, new targets and therapeutic strategies are urgently required. Here, we show that bone morphogenetic protein-4 (BMP4) blocks metastasis in animal models of breast cancer and predicts improved survival in patients. In preclinical models of spontaneous metastasis, BMP4 acted as an autocrine mediator to modulate a range of known metastasis-regulating genes, including Smad7, via activation of canonical BMP-SMAD signaling. Restored BMP4 expression or therapeutically administered BMP4 protein, blocked metastasis and increased survival by sensitizing cancer cells to anoikis, thereby reducing the number of circulating tumor cells. Gene silencing of Bmp4 or its downstream mediator Smad7, reversed this phenotype. Administration of recombinant BMP4 markedly reduced spontaneous metastasis to lung and bone. Elevated levels of BMP4 and SMAD7 were prognostic for improved recurrence-free survival and overall survival in patients with breast cancer, indicating the importance of canonical BMP4 signaling in the suppression of metastasis and highlighting new avenues for therapy against metastatic disease. SIGNIFICANCE: Targeting the BMP4-SMAD7 signaling axis presents a novel therapeutic strategy to combat metastatic breast cancer, a disease that has had no reduction in patient mortality over 20 years. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/6/1304/F1.large.jpg.

Deregulated bone morphogenetic proteins and their receptors are associated with disease progression of gastric cancer

Bone morphogenetic proteins (BMP) are members of the transforming growth factor β superfamily (TGF-β). BMPs are involved in tumourigenesis and disease progression of certain malignancies. To date, the role played by BMPs in gastric cancer (GC) remains largely unknown. In the present study, we systematically analysed the expression and clinical significance of BMP and BMP receptors (BMPR) in TCGA gastric cancer database and GEO database and explored the possible mechanism of action. BMP5 is reduced in gastric cancer tissues, while ACVRL1, ACVR1, TGFBR1, and BMPR2 were significantly increased in the gastric tumours. BMP3, ACVR1, TGFBR1, BMPR1B (also known as ALK6), TGFBR2 and BMPR2 were significantly associated with poorer overall survival of GC patients. A negative correlation was seen between BMP/BMPR and proliferation markers which was supported by their correlation with the cell cycle promoters and inhibitors. More interestingly, further analyses showed that BMPs and their receptors are positively correlated with matrix metalloproteinases (MMPs), epithelial mesenchymal transition (EMT) markers and stemness in GC. Furthermore, positive correlations were also frequently seen between BMP receptors and markers/regulators of angiogenesis and lymphangiogenesis in the gastric tumours. Taken together, these findings suggest that BMPs play dual roles in GC. They may inhibit proliferation of GC cells. On the other hand, they can also promote disease progression through a promotion of invasion, EMT and stemness. The elevated expression of BMP receptors in GC were also highly associated with tumour associated angiogenesis and lymphangiogenesis which facilitate tumour growth, expansion and spread.

Characterization of triple-negative breast cancer preclinical models provides functional evidence of metastatic progression

Triple-negative breast cancer (TNBC), an aggressive, metastatic and recurrent breast cancer (BC) subtype, currently suffers from a lack of adequately described spontaneously metastatic preclinical models that faithfully reproduce the clinical scenario. We describe two preclinical spontaneously metastatic TNBC orthotopic murine models for the development of advanced therapeutics: an immunodeficient human MDA-MB-231-Luc model and an immunocompetent mouse 4T1 model. Furthermore, we provide a broad range of multifactorial analysis for both models that could provide relevant information for the development of new therapies and diagnostic tools. Our comparisons uncovered differential growth rates, stromal arrangements and metabolic profiles in primary tumors, and the presence of cancer-associated adipocyte infiltration in the MDA-MB-231-Luc model. Histopathological studies highlighted the more rapid metastatic spread to the lungs in the 4T1 model following a lymphatic route, while we observed both homogeneous (MDA-MB-231-Luc) and heterogeneous (4T1) metastatic spread to axillary lymph nodes. We encountered unique metabolomic signatures in each model, including crucial amino acids and cell membrane components. Hematological analysis demonstrated severe leukemoid and lymphoid reactions in the 4T1 model with the partial reestablishment of immune responses in the immunocompromised MDA-MB-231-Luc model. Additionally, we discovered β-immunoglobulinemia and increased basal levels of G-CSF correlating with a metastatic switch, with G-CSF also promoting extramedullary hematopoiesis (both models) and causing hepatosplenomegaly (4T1 model). Overall, we believe that the characterization of these preclinical models will foster the development of advanced therapeutic strategies for TNBC treatment, especially for the treatment of patients presenting both, primary tumors and metastatic spread.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.