Dysregulation of macrophage polarization is associated with the metastatic process in osteosarcoma

Ferroptosis contributes to the progression of female-specific neoplasms, from breast cancer to gynecological malignancies in a manner regulated by non-coding RNAs: Mechanistic implications

Ferroptosis, a recently identified type of non-apoptotic cell death, triggers the elimination of cells in the presence of lipid peroxidation and in an iron-dependent manner. Indeed, ferroptosis-stimulating factors have the ability of suppressing antioxidant capacity, leading to the accumulation of reactive oxygen species (ROS) and the subsequent oxidative death of the cells. Ferroptosis is involved in the pathophysiological basis of different maladies, such as multiple cancers, among which female-oriented malignancies have attracted much attention in recent years. In this context, it has also been unveiled that non-coding RNA transcripts, including microRNAs, long non-coding RNAs, and circular RNAs have regulatory interconnections with the ferroptotic flux, which controls the pathogenic development of diseases. Furthermore, the potential of employing these RNA transcripts as therapeutic targets during the onset of female-specific neoplasms to modulate ferroptosis has become a research hotspot; however, the molecular mechanisms and functional alterations of ferroptosis still require further investigation. The current review comprehensively highlights ferroptosis and its association with non-coding RNAs with a focus on how this crosstalk affects the pathogenesis of female-oriented malignancies, from breast cancer to ovarian, cervical, and endometrial neoplasms, suggesting novel therapeutic targets to decelerate and even block the expansion and development of these tumors.

Prognostic value of hemogram parameters in osteosarcoma: The French OS2006 experience

BACKGROUND

Previous studies have shown that neutrophil-to-lymphocyte (NLR) ratio at diagnosis and early lymphocytes recovery on doxorubicin-based chemotherapy, may impact the outcome in patients with osteosarcoma (OST). This study aimed to evaluate the prognostic value of hemogram parameters in patients with OST treated with high-dose methotrexate and etoposide/ifosfamide (M-EI) chemotherapy.

MATERIALS AND METHODS

We retrospectively analyzed the prognostic value of various hemogram parameters at diagnosis and during therapy in a large consecutive cohort of patients with OST included in the French OS2006 trial and treated with M-EI chemotherapy.

RESULTS

A total of 164 patients were analyzed. The median age was 14.7 years (interquartile range [IQR]: 11.7-17). Median follow-up was 5.6 years (IQR: 3.3-7.7 years). Three-year event-free survival (EFS) and overall survival (OS) were 71.5% (95% confidence interval [CI]: 64%-78%) and 86.4% (95% CI: 80%-91%), respectively. In univariate analysis, blood count parameters at diagnosis and early lymphocyte recovery at Day 14 were not found prognostic of survival outcomes. By contrast, an increase of NLR ratio at Day 1 of the first EI chemotherapy (NLR-W4) was associated with reduced OS in univariate (p = .0044) and multivariate analysis (hazards ratio [HR] = 1.3, 95% CI: 1.1-1.5; p = .002), although not with EFS. After adjustment on histological response and metastatic status, an increase of the ratio NLR-W4 of 1 was associated with an increased risk of death of 30%.

CONCLUSIONS

We identified NLR-W4 as a potential early biomarker for survival in patients with OST treated with M-EI chemotherapy. Further studies are required to confirm the prognostic value of NLR and better identify immune mechanisms involved in disease surveillance.

Clinical and translational implications of immunotherapy in sarcomas

Immunotherapy has emerged as promising treatment in sarcomas, but the high variability in terms of histology, clinical behavior and response to treatments determines a particular challenge for its role in these neoplasms. Tumor immune microenvironment (TiME) of sarcomas reflects the heterogeneity of these tumors originating from mesenchymal cells and encompassing more than 100 histologies. Advances in the understanding of the complexity of TiME have led to an improvement of the immunotherapeutic responsiveness in sarcomas, that at first showed disappointing results. The proposed immune-classification of sarcomas based on the interaction between immune cell populations and tumor cells showed to have a prognostic and potential predictive role for immunotherapies. Several studies have explored the clinical impact of immune therapies in the management of these histotypes leading to controversial results. The presence of Tumor Infiltrating Lymphocytes (TIL) seems to correlate with an improvement in the survival of patients and with a higher responsiveness to immunotherapy. In this context, it is important to consider that also immune-related genes (IRGs) have been demonstrated to have a key role in tumorigenesis and in the building of tumor immune microenvironment. The IRGs landscape in soft tissue and bone sarcomas is characterized by the connection between several tumor-related genes that can assume a potential prognostic and predictive therapeutic role. In this paper, we reviewed the state of art of the principal immune strategies in the management of sarcomas including their clinical and translational relevance.

Advancements in osteosarcoma management: integrating immune microenvironment insights with immunotherapeutic strategies

Osteosarcoma, a malignant bone tumor predominantly affecting children and adolescents, presents significant therapeutic challenges, particularly in metastatic or recurrent cases. Conventional surgical and chemotherapeutic approaches have achieved partial therapeutic efficacy; however, the prognosis for long-term survival remains bleak. Recent studies have highlighted the imperative for a comprehensive exploration of the osteosarcoma immune microenvironment, focusing on the integration of diverse immunotherapeutic strategies-including immune checkpoint inhibitors, tumor microenvironment modulators, cytokine therapies, tumor antigen-specific interventions, cancer vaccines, cellular therapies, and antibody-based treatments-that are directly pertinent to modulating this intricate microenvironment. By targeting tumor cells, modulating the tumor microenvironment, and activating host immune responses, these innovative approaches have demonstrated substantial potential in enhancing the effectiveness of osteosarcoma treatments. Although most of these novel strategies are still in research or clinical trial phases, they have already demonstrated significant potential for individuals with osteosarcoma, suggesting the possibility of developing new, more personalized and effective treatment options. This review aims to provide a comprehensive overview of the current advancements in osteosarcoma immunotherapy, emphasizing the significance of integrating various immunotherapeutic methods to optimize therapeutic outcomes. Additionally, it underscores the imperative for subsequent research to further investigate the intricate interactions between the tumor microenvironment and the immune system, aiming to devise more effective treatment strategies. The present review comprehensively addresses the landscape of osteosarcoma immunotherapy, delineating crucial scientific concerns and clinical challenges, thereby outlining potential research directions.

Osteosarcoma in a ceRNET perspective

Osteosarcoma (OS) is the most prevalent and fatal type of bone tumor. It is characterized by great heterogeneity of genomic aberrations, mutated genes, and cell types contribution, making therapy and patients management particularly challenging. A unifying picture of molecular mechanisms underlying the disease could help to transform those challenges into opportunities.This review deeply explores the occurrence in OS of large-scale RNA regulatory networks, denominated "competing endogenous RNA network" (ceRNET), wherein different RNA biotypes, such as long non-coding RNAs, circular RNAs and mRNAs can functionally interact each other by competitively binding to shared microRNAs. Here, we discuss how the unbalancing of any network component can derail the entire circuit, driving OS onset and progression by impacting on cell proliferation, migration, invasion, tumor growth and metastasis, and even chemotherapeutic resistance, as distilled from many studies. Intriguingly, the aberrant expression of the networks components in OS cells can be triggered also by the surroundings, through cytokines and vesicles, with their bioactive cargo of proteins and non-coding RNAs, highlighting the relevance of tumor microenvironment. A comprehensive picture of RNA regulatory networks underlying OS could pave the way for the development of innovative RNA-targeted and RNA-based therapies and new diagnostic tools, also in the perspective of precision oncology.

From biology to personalized medicine: Recent knowledge in osteosarcoma

High-grade osteosarcoma is the most common paediatric bone cancer. More than one third of patients relapse and die of osteosarcoma using current chemotherapeutic and surgical strategies. To improve outcomes in osteosarcoma, two crucial challenges need to be tackled: 1-the identification of hard-to-treat disease, ideally from diagnosis; 2- choosing the best combined or novel therapies to eradicate tumor cells which are resistant to current therapies leading to disease dissemination and metastasize as well as their favorable microenvironment. Genetic chaos, tumor complexity and heterogeneity render this task difficult. The development of new technologies like next generation sequencing has led to an improvement in osteosarcoma oncogenesis knownledge. This review summarizes recent biological and therapeutical advances in osteosarcoma, as well as the challenges that must be overcome in order to develop personalized medicine and new therapeutic strategies and ultimately improve patient survival.

Extracellular Vesicles from Highly Metastatic Osteosarcoma Cells Induce Pro-Tumorigenic Macrophage Phenotypes

Metastasis is the principal factor in poor prognosis for individuals with osteosarcoma (OS). Understanding the events that lead to metastasis is critical to develop better interventions for this disease. Alveolar macrophages are potentially involved in priming the lung microenvironment for OS metastasis, yet the mechanisms involved in this process remain unclear. Since extracellular vesicles (EVs) are a known actor in primary tumor development, their potential role in OS metastagenesis through macrophage modulation is explored here. The interaction of EVs isolated from highly metastatic (K7M2) and less metastatic (K12) osteosarcoma cell lines is compared with a peritoneal macrophage cell line. An EV concentration that reproducibly induced macrophage migration is identified first, then used for later experiments. By confocal microscopy, both EV types associated with M0 or M1 macrophages; however, only K7M2-EVs are associated with M2 macrophages, an interaction that is abrogated by EV pre-treatment with anti-CD47 antibody. Interestingly, all interactions appeared to be surface binding, not internalized. In functional studies, K7M2-EVs polarized fewer macrophages to M1. Together, these data suggest that K7M2-EVs have unique interactions with macrophages that can contribute to the production of a higher proportion of pro-tumor type macrophages, thereby accelerating metastasis.

Chimeric antigen receptor T cells in the treatment of osteosarcoma (Review)

Osteosarcoma (OS) is a frequently occurring primary bone tumor, mostly affecting children, adolescents and young adults. Before 1970, surgical resection was the main treatment method for OS, but the clinical results were not promising. Subsequently, the advent of chemotherapy has improved the prognosis of patients with OS. However, there is still a high incidence of metastasis or recurrence, and chemotherapy has several side effects, thus making the 5‑year survival rate markedly low. Recently, chimeric antigen receptor T (CAR‑T) cell therapy represents an alternative immunotherapy approach with significant potential for hematologic malignancies. Nevertheless, the application of CAR‑T cells in the treatment of OS faces numerous challenges. The present review focused on the advances in the development of CAR‑T cells to improve their clinical efficacy, and discussed ways to overcome the difficulties faced by CAR T‑cell therapy for OS.

Bulk and single-cell sequencing identified a prognostic model based on the macrophage and lipid metabolism related signatures for osteosarcoma patients

The introduction of multidrug combination chemotherapy has significantly advanced the long-term survival prospects for osteosarcoma (OS) patients over the past decades. However, the escalating prevalence of chemoresistance has emerged as a substantial impediment to further advancements, necessitating the formulation of innovative strategies. Our present study leveraged sophisticated bulk and single-cell sequencing techniques to scrutinize the OS immune microenvironment, unveiling a potential association between the differentiation state of macrophages and the efficacy of OS chemotherapy. Notably, we observed that a heightened presence of lipid metabolism genes and pathways in predifferentiated macrophages, constituting the major cluster of OS patients exhibiting a less favorable response to chemotherapy. Subsequently, we developed a robust Macrophage and Lipid Metabolism (MLMR) risk model and a nomogram, both of which demonstrated commendable prognostic predictive performance. Furthermore, a comprehensive investigation into the underlying mechanisms of the risk model revealed intricate associations with variations in the immune response among OS patients. Finally, our meticulous drug sensitivity analysis identified a spectrum of potential therapeutic agents for OS, including AZD2014, Sapitinib, Buparlisib, Afuresertib, MIRA-1, and BIBR-1532. These findings significantly augment the therapeutic arsenal available to clinicians managing OS, presenting a promising avenue for elevating treatment outcomes.

Exploring the Impact of Exosomal Cargos on Osteosarcoma Progression: Insights into Therapeutic Potential

Osteosarcoma (OS) is a primary malignant bone tumor with high metastasis. Poor prognosis highlights a clinical need for novel therapeutic strategies. Exosomes, also known as extracellular vesicles, have been identified as essential players in the modulation of cancer. Recent studies have suggested that OS-derived exosomes can drive pro-tumorigenic or anti-tumorigenic phenotypes by transferring specific cargos, including proteins, nucleic acids, and metabolites, to neighboring cells, significantly impacting the regulation of cellular processes. This review discusses the advancement of exosomes and their cargos in OS. We examine how these exosomes contribute to the modulation of cellular phenotypes associated with tumor progression and metastasis. Furthermore, we explore the potential of exosomes as valuable biomarkers for diagnostics and prognostic purposes and their role in shaping innovative therapeutic strategies in OS treatment development.

Exploring the modulation of MLH1 and MSH2 gene expression in hesperetin-treated breast cancer cells (BT-474)

The major mortality factor for women globally is breast cancer, and current treatments have several adverse effects. Hesperetin (HSP) is a flavone that occurs naturally with anti-tumor capabilities and has been investigated as a potential treatment for cancer. This study aimed to investigate the cytotoxic and anti-malignant potential of HSP on breast cancer cells (BT-474) and normal cells (MCF-10a). The results indicated that HSP has dose-dependent cytotoxicity in BT-474 and MCF-10a cells. The elevated concentration of HSP lowered cell viability and proliferation. The half-maximal inhibitory concentration (IC50) of HSP in BT-474 cancer cells after a 48-h exposure was 279.2 μM/ml, while the IC50 in normal cells was 855.4 μM/ml. The cytotoxicity of HSP was more significant in cancer cell lines than in normal cell lines and this aspect presents a favorable factor in utilizing the drug for the treatment of breast cancer. The apoptotic effect of HSP in BT-474 cells was investigated, and it was found that the higher the concentration of HSP more the cells underwent apoptosis. Furthermore, the highest concentration of HSP led to overexpression of the MLH1 and MSH2 genes in both breast cancer and normal cell lines. Overall, our study suggests that HSP has an anticancer effect on breast cancer cell lines, and the effect is concentration dependent.

Patterns of metastatic progression and association with clinical outcomes in canine osteosarcoma: A necropsy study of 83 dogs

Osteosarcoma is a highly metastatic primary bone tumour that occurs spontaneously in both pet dogs and humans. Patterns of metastasis to organs beyond the most common site (lung) are poorly characterised and it is unknown whether specific associations between patterns of metastatic progression and patient features exist. This retrospective study characterised the necropsy findings of 83 dogs receiving standardised therapy and clinical monitoring in a prospective clinical trial setting to document patterns of metastasis and correlate outcomes with these patterns and other patient and tumour-specific factors. A total of 20 different sites of metastasis were documented, with lung as the most common site, followed by bone, kidney, liver, and heart. Two distinct clusters of dogs were identified based on patterns of metastasis. There was no significant association between site of enrollment, trial arm, sex, serum alkaline phosphatase (ALP) activity, or tumour location and clinical outcomes. A second cancer type was identified at necropsy in 10 dogs (10/83; 12%). These data showcase the extensive nature of osteosarcoma metastasis beyond the lung and provide a benchmark for clinical monitoring of the disease. Further, this study provides insight into transcriptional features of primary tumours that may relate to a propensity for osteosarcoma metastasis to specific organs and tissues.

Correlation between 18F-FDG PET-derived parameters and quantitative pathological characteristics of soft tissue sarcoma

Background

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) has been widely used for evaluating patients with soft tissue sarcoma (STS). However, uncertainties and overlap among individuals may be observed, and the relevance of these findings remains to be further explored. The present study was aimed at investigating the correlation between PET metabolic parameters and quantitative pathological characteristics in STS.

Methods

We retrospectively collected 39 patients with STS who underwent 18F-FDG PET/computed tomography (CT) examination before treatment. Metabolic parameters including the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and intratumoral FDG uptake heterogeneity (IFH) were measured. Histological grading was performed according to the French Federation of Cancer Centers grading system. Continuous staining of tissue sections and digital quantitative analysis methods were used, the characteristics of tumor nucleated cells were observed through hematoxylin-eosin staining, and the expression of CD163, CD68, CD8, and CD4 in tumor tissues was determined by immunohistochemistry (IHC), then the correlation between FDG metabolic parameters and the above quantitative pathological characteristics in patients with STS were evaluated.

Results

The SUVmax of 18F-FDG PET/CT in STS was positively correlated with the total nuclear area (r=0.355, P=0.027). SUVmax was also positively correlated with the expression levels of CD163, CD68, CD8, and CD4 (r=0.582, 0.485, 0.343, and 0.324, with P<0.001, 0.002, 0.032, and 0.044, respectively), but was not significantly correlated with cell count and mean nuclear area (all P>0.05). However, MTV, TLG, and IFH were not significantly correlated with the above quantitative pathological characteristics. Further multivariate logistic regression analysis indicated that only CD163 expression and histological grade were independently correlated with SUVmax. Moreover, SUVmax remained positively correlated with CD163 expression in the low-grade STS (r=0.820, P=0.001) and high-grade STS groups (r=0.430, P=0.028).

Conclusions

18F-FDG uptake was positively correlated with the quantitative pathological features of soft tissue tumors. SUVmax may be a meaningful method reflecting the level of M2 macrophage infiltration and may provide additional valuable information for preclinical evaluation of STS.

The Role of Macrophages in Sarcoma Tumor Microenvironment and Treatment

Sarcomas are a heterogeneous group of malignant mesenchymal tumors, including soft tissue and bone sarcomas. Macrophages in the tumor microenvironment, involved in immunosuppression and leading to tumor development, are called tumor-associated macrophages (TAMs). TAMs are very important in modulating the microenvironment of sarcomas by expressing specific markers and secreting factors that influence immune and tumor cells. They are involved in many signaling pathways, such as p-STAT3/p-Erk1/2, PI3K/Akt, JAK/MAPK, and JAK/STAT3. TAMs also significantly impact the clinical outcomes of patients suffering from sarcomas and are mainly related to poor overall survival rates among bone and soft tissue sarcomas, for example, chondrosarcoma, osteosarcoma, liposarcoma, synovial sarcoma, and undifferentiated pleomorphic sarcoma. This review summarizes the current knowledge on TAMs in sarcomas, focusing on specific markers on sarcoma cells, cell-cell interactions, and the possibly involved molecular pathways. Furthermore, we discuss the clinical significance of macrophages in sarcomas as a potential target for new therapies, presenting clinical relevance, possible new treatment options, and ongoing clinical trials using TAMs in sarcoma treatment.

New gene signature from the dominant infiltration immune cell type in osteosarcoma predicts overall survival

The immune microenvironment of osteosarcoma (OS) has been reported to play an important role in disease progression and prognosis. However, owing to tumor heterogeneity, it is not ideal to predict OS prognosis by examining only infiltrating immune cells. This work aimed to build a prognostic gene signature based on similarities in the immune microenvironments of OS patients. Public datasets were used to examine the correlated genes, and the most consistent dominant infiltrating immune cell type was identified. The LASSO Cox regression model was used to establish a multiple-gene risk prediction signature. A nine-gene prognostic signature was generated from the correlated genes for M0 macrophages and then proven to be effective and reliable in validation cohorts. Signature comparison indicated the priority of the signature. Multivariate Cox regression models indicated that the signature risk score is an independent prognostic factor for OS patients regardless of the Huvos grade in all datasets. In addition, the results of the association between the signature risk score and chemotherapy sensitivity also showed that there was no significant difference in the sensitivity of any drugs between the low- and high-risk groups. A GSEA of GO and KEGG pathways found that antigen processing- and presentation-related biological functions and olfactory transduction receptor signaling pathways have important roles in signature functioning. Our findings showed that M0 macrophages were the dominant infiltrating immune cell type in OS and that the new gene signature is a promising prognostic model for OS patients.

Ablative and Immunostimulatory Effects of Histotripsy Ablation in a Murine Osteosarcoma Model

Background: Osteosarcoma (OS) is the most frequently occurring malignant bone tumor in humans, primarily affecting children and adolescents. Significant advancements in treatment options for OS have not occurred in the last several decades, and the prognosis remains grim with only a 70% rate of 5-year survival. The objective of this study was to investigate the focused ultrasound technique of histotripsy as a novel, noninvasive treatment option for OS. Methods: We utilized a heterotopic OS murine model to establish the feasibility of ablating OS tumors with histotripsy in a preclinical setting. We investigated the local immune response within the tumor microenvironment (TME) via immune cell phenotyping and gene expression analysis. Findings: We established the feasibility of ablating heterotopic OS tumors with ablation characterized microscopically by loss of cellular architecture in targeted regions of tumors. We observed greater populations of macrophages and dendritic cells within treated tumors and the upregulation of immune activating genes 72 h after histotripsy ablation. Interpretation: This study was the first to investigate histotripsy ablation for OS in a preclinical murine model, with results suggesting local immunomodulation within the TME. Our results support the continued investigation of histotripsy as a novel noninvasive treatment option for OS patients to improve clinical outcomes and patient prognosis.

Engineered bone marrow as a clinically relevant ex vivo model for primary bone cancer research and drug screening

Osteosarcoma (OS) is the most common primary malignant bone cancer in children and adolescents. While numerous other cancers now have promising therapeutic advances, treatment options for OS have remained unchanged since the advent of standard chemotherapeutics and offer less than a 25% 5-y survival rate for those with metastatic disease. This dearth of clinical progress underscores a lack of understanding of OS progression and necessitates the study of this disease in an innovative system. Here, we adapt a previously described engineered bone marrow (eBM) construct for use as a three-dimensional platform to study how microenvironmental and immune factors affect OS tumor progression. We form eBM by implanting acellular bone-forming materials in mice and explanting the cellularized constructs after 8 wk for study. We interrogate the influence of the anatomical implantation site on eBM tissue quality, test ex vivo stability under normoxic (5% O2) and standard (21% O2) culture conditions, culture OS cells within these constructs, and compare them to human OS samples. We show that eBM stably recapitulates the composition of native bone marrow. OS cells exhibit differential behavior dependent on metastatic potential when cultured in eBM, thus mimicking in vivo conditions. Furthermore, we highlight the clinical applicability of eBM as a drug-screening platform through doxorubicin treatment and show that eBM confers a protective effect on OS cells that parallel clinical responses. Combined, this work presents eBM as a cellular construct that mimics the complex bone marrow environment that is useful for mechanistic bone cancer research and drug screening.

Hesperetin effect on MLH1 and MSH2 expression on breast cancer cells BT-549

Due to its genetic and phenotypic heterogeneity, breast cancer is very difficult to eliminate. The harmful consequences of conventional therapies like radiation and chemotherapy have prompted the search for organic-based alternatives. Hesperetin (HSP), a flavonoid, has been discovered to possess the ability to hinder the proliferation of cell associated with breast cancer by acting as an epigenetic agent and modifying gene expression. In this investigation, breast cancer cells (BT-549) and normal cells (MCF-10a) were subjected to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test and three different doses (200, 400, and 600 μM/mL) of HSP for real-time polymerase chain reaction and flow cytometry to examine its cytotoxic and anti-malignant potential. HSP was shown to be cytotoxic to both normal and breast cancer cells, but had a more pronounced effect on the cancer cell lines. After 48 h of treatment, the half-maximal inhibitory concentration (IC50) for BT-549 was 279.2 μM/mL, whereas the IC50 for MCF-10a was 855.4 μM/mL. At high HSP concentrations, upregulation of the MLH1 and MSH2 genes was observed in both cell lines. The influence of HSP on MLH1 gene expression was concentration dependent. Moreover, HSP had a concentration-dependent effect on MSH2 gene expression in the BT-549 cell line but not in the MCF-10a cell line. Cell death and early apoptosis were shown to be concentration dependent upon the application of HSP, as determined by flow cytometric analysis. HSP's capacity to cause apoptosis and its stronger impact on the malignant cell line when analyzed with the normal cell line imply that it might be useful as an effective therapeutic approach for combating breast cancer.

Rewiring innate and adaptive immunity with TLR9 agonist to treat osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary bone tumor in children and adolescent. Surgery and multidrug chemotherapy are the standard of treatment achieving 60-70% of event-free survival for localized disease at diagnosis. However, for metastatic disease, the prognosis is dismal. Exploiting immune system activation in the setting of such unfavorable mesenchymal tumors represents a new therapeutic challenge.

METHODS

In immune competent OS mouse models bearing two contralateral lesions, we tested the efficacy of intralesional administration of a TLR9 agonist against the treated and not treated contralateral lesion evaluating abscopal effect. Multiparametric flow cytometry was used to evaluate changes of the tumor immune microenviroment. Experiments in immune-deficient mice allowed the investigation of the role of adaptive T cells in TLR9 agonist effects, while T cell receptor sequencing was used to assess the expansion of specific T cell clones.

RESULTS

TLR9 agonist strongly impaired the growth of locally-treated tumors and its therapeutic effect also extended to the contralateral, untreated lesion. Multiparametric flow cytometry showed conspicuous changes in the immune landscape of the OS immune microenvironment upon TLR9 engagement, involving a reduction in M2-like macrophages, paralleled by increased infiltration of dendritic cells and activated CD8 T cells in both lesions. Remarkably, CD8 T cells were needed for the induction of the abscopal effect, whereas they were not strictly necessary for halting the growth of the treated lesion. T cell receptor (TCR) sequencing of tumor infiltrating CD8 T cells showed the expansion of specific TCR clones in the treated tumors and, remarkably, their selected representation in the contralateral untreated lesions, providing the first evidence of the rewiring of tumor-associated T cell clonal architectures.

CONCLUSIONS

Overall these data indicate that the TLR9 agonist acts as an in situ anti-tumor vaccine, activating an innate immune response sufficient to suppress local tumor growth while inducing a systemic adaptive immunity with selective expansion of CD8 T cell clones, which are needed for the abscopal effect.

Advances in Osteosarcoma

PURPOSE OF REVIEW

This article gives a brief overview of the most recent developments in osteosarcoma treatment, including targeting of signaling pathways, immune checkpoint inhibitors, drug delivery strategies as single or combined approaches, and the identification of new therapeutic targets to face this highly heterogeneous disease.

RECENT FINDINGS

Osteosarcoma is one of the most common primary malignant bone tumors in children and young adults, with a high risk of bone and lung metastases and a 5-year survival rate around 70% in the absence of metastases and 30% if metastases are detected at the time of diagnosis. Despite the novel advances in neoadjuvant chemotherapy, the effective treatment for osteosarcoma has not improved in the last 4 decades. The emergence of immunotherapy has transformed the paradigm of treatment, focusing therapeutic strategies on the potential of immune checkpoint inhibitors. However, the most recent clinical trials show a slight improvement over the conventional polychemotherapy scheme. The tumor microenvironment plays a crucial role in the pathogenesis of osteosarcoma by controlling the tumor growth, the metastatic process and the drug resistance and paved the way of new therapeutic options that must be validated by accurate pre-clinical studies and clinical trials.

Predictive Biomarkers of Pathological Response to Neoadjuvant Chemoradiotherapy for Locally Advanced Soft Tissue Sarcomas

BACKGROUND

Marginally resectable and unresectable soft tissue sarcomas (STS) remain a therapy challenge due to the lack of highly active treatment. The aim of the study was to identify a biomarker to predict the pathological response (PR) to preplanned treatment of these STSs.

METHODS

In the phase II clinical trial (NCT03651375), locally advanced STS patients received preoperative treatment with a combination of doxorubicin-ifosfamide chemotherapy and 5 × 5 Gy radiotherapy. PR to the treatment was classified using the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group recommendations. We have chosen HIF-1α, CD163, CD68, CD34, CD105, and γH2AFX proteins, rendering different biological phenomena, for biomarker study.

RESULTS

Nineteen patients were enrolled and in four cases a good PR was reported. The high expression of HIF-1α before surgery showed a negative correlation with PR, which means a poor response to therapy. Furthermore, the samples after surgery had decreased expression of HIF-1α, which confirmed the correlation with PR. However, high expression of γH2AFX positively correlated with PR, which provides better PR. The high number of positive-staining TAMs and the high IMVD did not correlate with PR.

CONCLUSIONS

HIF1α and γH2AFX could be potential biomarkers for PR prediction after neoadjuvant treatment in STS.

Tumor-associated macrophages induce inflammation and drug resistance in a mechanically tunable engineered model of osteosarcoma

The tumor microenvironment is a complex and dynamic ecosystem composed of various physical cues and biochemical signals that facilitate cancer progression, and tumor-associated macrophages are especially of interest as a treatable target due to their diverse pro-tumorigenic functions. Engineered three-dimensional models of tumors more effectively mimic the tumor microenvironment than monolayer cultures and can serve as a platform for investigating specific aspects of tumor biology within a controlled setting. To study the combinatorial effects of tumor-associated macrophages and microenvironment mechanical properties on osteosarcoma, we co-cultured human osteosarcoma cells with macrophages within biomaterials-based bone tumor niches with tunable stiffness. In the first 24 h of direct interaction between the two cell types, macrophages induced an inflammatory environment consisting of high concentrations of tumor necrosis factor alpha (TNFα) and interleukin (IL)-6 within moderately stiff scaffolds. Expression of Yes-associated protein (YAP), but not its homolog, transcriptional activator with PDZ-binding motif (TAZ), in osteosarcoma cells was significantly higher than in macrophages, and co-culture of the two cells slightly upregulated YAP in both cells, although not to a significant degree. Resistance to doxorubicin treatment in osteosarcoma cells was correlated with inflammation in the microenvironment, and signal transducer and activator of transcription 3 (STAT3) inhibition diminished the inflammation-related differences in drug resistance but ultimately did not improve the efficacy of doxorubicin. This work highlights that the biochemical cues conferred by tumor-associated macrophages in osteosarcoma are highly variable, and signals derived from the immune system should be considered in the development and testing of novel drugs for cancer.

Current Landscape of Immunotherapy for Advanced Sarcoma

There is substantial heterogeneity between different subtypes of sarcoma regarding their biological behavior and microenvironment, which impacts their responsiveness to immunotherapy. Alveolar soft-part sarcoma, synovial sarcoma and undifferentiated pleomorphic sarcoma show higher immunogenicity and better responses to checkpoint inhibitors. Combination strategies adding immunotherapy to chemotherapy and/or tyrosine-kinase inhibitors globally seem superior to single-agent schemes. Therapeutic vaccines and different forms of adoptive cell therapy, mainly engineered TCRs, CAR-T cells and TIL therapy, are emerging as new forms of immunotherapy for advanced solid tumors. Tumor lymphocytic infiltration and other prognostic and predictive biomarkers are under research.

Naturally occurring canine sarcomas: Bridging the gap from mouse models to human patients through cross-disciplinary research partnerships

Fueled by support from the National Cancer Institute's "Cancer Moonshot" program, the past few years have witnessed a renewed interest in the canine spontaneous cancer model as an invaluable resource in translational oncology research. Increasingly, there is awareness that pet dogs with cancer provide an accessible bridge to improving the efficiency of cancer drug discovery and clinical therapeutic development. Canine tumors share many biological, genetic, and histologic features with their human tumor counterparts, and most importantly, retain the complexities of naturally occurring drug resistance, metastasis, and tumor-host immune interactions, all of which are difficult to recapitulate in induced or genetically engineered murine tumor models. The utility of canine models has been particularly apparent in sarcoma research, where the increased incidence of sarcomas in dogs as compared to people has facilitated comparative research resulting in treatment advances benefitting both species. Although there is an increasing awareness of the advantages in using spontaneous canine sarcoma models for research, these models remain underutilized, in part due to a lack of more permanent institutional and cross-institutional infrastructure to support partnerships between veterinary and human clinician-scientists. In this review, we provide an updated overview of historical and current applications of spontaneously occurring canine tumor models in sarcoma research, with particular attention to knowledge gaps, limitations, and growth opportunities within these applications. Furthermore, we propose considerations for working within existing veterinary translational and comparative oncology research infrastructures to maximize the benefit of partnerships between veterinary and human biomedical researchers within and across institutions to improve the utility and application of spontaneous canine sarcomas in translational oncology research.

NOTCH Signaling in Osteosarcoma

The combination of neoadjuvant chemotherapy and surgery has been promoted for the treatment of osteosarcoma; however, the local recurrence and lung metastasis rates remain high. Therefore, it is crucial to explore new therapeutic targets and strategies that are more effective. The NOTCH pathway is not only involved in normal embryonic development but also plays an important role in the development of cancers. The expression level and signaling functional status of the NOTCH pathway vary in different histological types of cancer as well as in the same type of cancer from different patients, reflecting the distinct roles of the Notch pathway in tumorigenesis. Studies have reported abnormal activation of the NOTCH signaling pathway in most clinical specimens of osteosarcoma, which is closely related to a poor prognosis. Similarly, studies have reported that NOTCH signaling affected the biological behavior of osteosarcoma through various molecular mechanisms. NOTCH-targeted therapy has shown potential for the treatment of osteosarcoma in clinical research. After the introduction of the composition and biological functions of the NOTCH signaling pathway, the review paper discussed the clinical significance of dysfunction in osteosarcoma. Then the paper reviewed the recent relevant research progress made both in the cell lines and in the animal models of osteosarcoma. Finally, the paper explored the potential of the clinical application of NOTCH-targeted therapy for the treatment of osteosarcoma.

Macrophage Biomarkers sCD163 and sSIRPα in Serum Predict Mortality in Sarcoma Patients

Most soft tissue sarcoma (STS) patients do not respond to traditional checkpoint inhibitor treatment, which may be due to infiltrating immunosuppressive tumour-associated macrophages. This study investigated the prognostic value of four serum macrophage biomarkers. Methods: Blood samples were taken from 152 patients with STS at the time of diagnosis; clinical data were prospectively collected. The concentrations of four macrophage biomarkers (sCD163, sCD206, sSIRPα, sLILRB1) were measured in serum, dichotomised based on median concentration, and evaluated either individually or when combined with established prognostic markers. Results: All macrophage biomarkers were prognostic of overall survival (OS). However, only sCD163 and sSIRPα were prognostic for recurrent disease (sCD163: hazard ratio (HR): 1.97 (95% CI: 1.10-3.51) and sSIRPα: HR: 2.09 (95% CI: 1.16-3.77)). A prognostic profile was made based on sCD163 and sSIRPα; it also included c-reactive protein and tumour grade. Patients with intermediate- or high-risk prognostic profiles (adjusted for age and tumour size) had a higher risk of recurrent disease compared to low-risk patients (HR: 2.64 (95% CI: 0.97-7.19)) and (HR 4.3 (95% CI: 1.62-11.47)), respectively. Conclusion: This study demonstrated that serum biomarkers of immunosuppressive macrophages were prognostic for OS; when combined with well-established markers of recurrence they allowed for a clinically relevant categorising of patients.

Characterization of the Tumor Microenvironment in Jaw Osteosarcomas, towards Prognostic Markers and New Therapeutic Targets

Background-The purpose of this study was to investigate the bone resorption, as well as the vascular and immune microenvironment, of jaw osteosarcomas (JO) and to correlate these features with patient clinical outcomes. Methods-We studied 50 JO biopsy samples by immunohistochemical analysis of tissue microarrays (TMAs). We investigated the bone remodeling markers RANK/RANKL/OPG, the endothelial glycoprotein CD146, and biomarkers of the immune environment (CD163 and CD68 of macrophages, CD4+ and CD8+ of tumor-infiltrating lymphocytes (TILs), and an immune checkpoint PD-1/PD-L1). The biomarkers were analyzed for their influence on progression (recurrence and metastasis), overall survival (OS), and disease-free survival (DFS). Results-A strong and significant correlation has been found between CD163 staining and lower OS and DFS. The level of CD4+ and CD8+ staining was low and non-significantly associated with survival outcomes. High levels of RANK and RANKL were found in the tumor samples and correlated with lower DFS. Conclusion-Our findings suggest that CD163+ TAMs represent markers of poor prognosis in JO. Targeting TAMs could represent a valuable therapeutic strategy in JO.

Macrophage Repolarization as a Therapeutic Strategy for Osteosarcoma

Macrophages are versatile immune cells and can adapt to both external stimuli and their surrounding environment. Macrophages are categorized into two major categories; M1 macrophages release pro-inflammatory cytokines and produce protective responses that lead to antimicrobial or antitumor activity. M2 or tumor-associated macrophages (TAM) release anti-inflammatory cytokines that support tumor growth, invasion capacity, and metastatic potential. Since macrophages can be re-polarized from an M2 to an M1 phenotype with a variety of strategies, this has emerged as an innovative anti-cancer approach. Osteosarcoma (OS) is a kind of bone cancer and consists of a complex niche, and immunotherapy is not very effective. Therefore, immediate attention to new strategies is required. We incorporated the recent studies that have used M2-M1 repolarization strategies in the aspect of treating OS cancer.

PITX1 suppresses osteosarcoma metastasis through exosomal LINC00662-mediated M2 macrophage polarization

Paired-like homeodomain transcription factor 1 (PITX1) is frequently downregulated in cancers, including osteosarcoma (OS). However, its role in OS remains unknown. Therefore, we aimed to explore the functions and potential mechanisms of PITX1 in OS malignant progression. Elevated PITX1 suppressed OS cell proliferation and migration, based on transwell, proliferation, and colony formation assays. Pathway enrichment analysis of differentially-expressed genes between PITX1-overexpressing and control OS cells indicated that PITX1 expression was associated with the FAK/Src and PI3k/Akt signaling pathways. Mechanistically, ubiquitination assays and rescue experiments showed that PITX1 interacted with transcription factor STAT3, leading to decreased STAT3 transcriptional activity, which repressed the expression of LINC00662. Specific knockdown of LINC00662 reduced the tumor growth and invasion of OS cells induced by downregulated PITX1. Moreover, exosomal LINC00662, derived from PITX1 knockdown OS cell lines activated M2 macrophages in cell co-culture assays. M2 macrophage secreted several cytokines, among which CCL22 was found to cause OS cell EMT. Collectively, our data indicate that PITX1 suppresses OS cell proliferation and metastasis by downregulating LINC00662. Moreover, LINC00662 can be packaged into OS cell-derived exosomes to mediate M2 macrophage polarization to promote OS metastasis via CCL22.

Strategies to Overcome Resistance to Immune-Based Therapies in Osteosarcoma

Improving the prognosis and cure rate of HGOSs (high-grade osteosarcomas) is an absolute need. Immune-based treatment approaches have been increasingly taken into consideration, in particular for metastatic, relapsed and refractory HGOS patients, to ameliorate the clinical results currently achieved. This review is intended to give an overview on the immunotherapeutic treatments targeting, counteracting or exploiting the different immune cell compartments that are present in the HGOS tumor microenvironment. The principle at the basis of these strategies and the possible mechanisms that HGOS cells may use to escape these treatments are presented and discussed. Finally, a list of the currently ongoing immune-based trials in HGOS is provided, together with the results that have been obtained in recently completed clinical studies. The different strategies that are presently under investigation, which are generally aimed at abrogating the immune evasion of HGOS cells, will hopefully help to indicate new treatment protocols, leading to an improvement in the prognosis of patients with this tumor.

Knowing the myeloid-derived suppressor cells : Another enemy of sarcomas patients

Sarcomas are heterogeneous and aggressive malignant tumors with variable responses to current standard treatments being usually incurable for those patients with metastatic and unresectable diseases. The lack of curative strategies has led to develop new therapies in the treatment of sarcomas where the role of immune system is an evolving field. Most sarcomas often exhibit an immunosuppressive microenvironment, which reduces their capacity to trigger an immune response. Therefore, sarcomas are broadly considered as an "immune cold" tumor, although some studies have described a great immune heterogeneity across sarcoma subtypes. Sarcoma cells, like other tumors, evade their immune destruction through a variety of mechanisms, including expansion and recruitment of myeloid derived suppressor cells (MDSCs). MDSCs are immature myeloid cells that have been correlated with a reduction of the therapeutic efficacy, including immunotherapy, tumor progression and worst prognosis. Consequently, different strategies have been developed in recent years to target MDSCs in cancer treatments. This chapter discusses the role of MDSCs in sarcomas and their current potential as a therapeutic target in these malignancies.

The interaction between osteosarcoma and other cells in the bone microenvironment: From mechanism to clinical applications

Osteosarcoma is a primary bone tumor with a high mortality rate. The event-free survival rate has not improved significantly in the past 30 years, which brings a heavy burden to patients and society. The high heterogeneity of osteosarcoma leads to the lack of specific targets and poor therapeutic effect. Tumor microenvironment is the focus of current research, and osteosarcoma is closely related to bone microenvironment. Many soluble factors and extracellular matrix secreted by many cells in the bone microenvironment have been shown to affect the occurrence, proliferation, invasion and metastasis of osteosarcoma through a variety of signaling pathways. Therefore, targeting other cells in the bone microenvironment may improve the prognosis of osteosarcoma. The mechanism by which osteosarcoma interacts with other cells in the bone microenvironment has been extensively investigated, but currently developed drugs targeting the bone microenvironment have poor efficacy. Therefore, we review the regulatory effects of major cells and physical and chemical properties in the bone microenvironment on osteosarcoma, focusing on their complex interactions, potential therapeutic strategies and clinical applications, to deepen our understanding of osteosarcoma and the bone microenvironment and provide reference for future treatment. Targeting other cells in the bone microenvironment may provide potential targets for the development of clinical drugs for osteosarcoma and may improve the prognosis of osteosarcoma.

Current State of Immunotherapy and Mechanisms of Immune Evasion in Ewing Sarcoma and Osteosarcoma

We argue here that in many ways, Ewing sarcoma (EwS) is a unique tumor entity and yet, it shares many commonalities with other immunologically cold solid malignancies. From the historical perspective, EwS, osteosarcoma (OS) and other bone and soft-tissue sarcomas were the first types of tumors treated with the immunotherapy approach: more than 100 years ago American surgeon William B. Coley injected his patients with a mixture of heat-inactivated bacteria, achieving survival rates apparently higher than with surgery alone. In contrast to OS which exhibits recurrent somatic copy-number alterations, EwS possesses one of the lowest mutation rates among cancers, being driven by a single oncogenic fusion protein, most frequently EWS-FLI1. In spite these differences, both EwS and OS are allied with immune tolerance and low immunogenicity. We discuss here the potential mechanisms of immune escape in these tumors, including low representation of tumor-specific antigens, low expression levels of MHC-I antigen-presenting molecules, accumulation of immunosuppressive M2 macrophages and myeloid proinflammatory cells, and release of extracellular vesicles (EVs) which are capable of reprogramming host cells in the tumor microenvironment and systemic circulation. We also discuss the vulnerabilities of EwS and OS and potential novel strategies for their targeting.

Tumor microenvironment in non-melanoma skin cancer resistance to photodynamic therapy

Non-melanoma skin cancer has recently seen an increase in prevalence, and it is estimated that this grow will continue in the coming years. In this sense, the importance of therapy effectiveness has increased, especially photodynamic therapy. Photodynamic therapy has attracted much attention as a minimally invasive, selective and repeatable approach for skin cancer treatment and prevention. Although its high efficiency, this strategy has also faced problems related to tumor resistance, where the tumor microenvironment has gained a well-deserved role in recent years. Tumor microenvironment denotes a wide variety of elements, such as cancer-associated fibroblasts, immune cells, endothelial cells or the extracellular matrix, where their interaction and the secretion of a wide diversity of cytokines. Therefore, the need of designing new strategies targeting elements of the tumor microenvironment to overcome the observed resistance has become evident. To this end, in this review we focus on the role of cancer-associated fibroblasts and tumor-associated macrophages in the resistance to photodynamic therapy. We are also exploring new approaches consisting in the combination of new and old drugs targeting these cells with photodynamic therapy to enhance treatment outcomes of non-melanoma skin cancer.

Lipopolysaccharide-binding protein expression is associated to the metastatic status of osteosarcoma patients

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Intratumour Gram^- bacteria can be detected in OS.

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Enriched intratumour in Gram^- bacteria infiltrate is associated with local disease.

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A poor Gram^- bacteria infiltration may be predict a higher risk of metastasis.

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Immune stimulation of OS by LPS represents a potential therapeutic option.

Osteosarcoma (OS) is a rare malignant primary bone tumours characterized by a high genetic and cell composition heterogeneity. Unfortunately, despite the use of drug combinations and the recent development of immunotherapies, the overall survival has not improved in the last four decades. Due to the key role of the tumour microenvironment in the pathogenesis of OS, a better understanding of its microenvironment is mandatory to develop new therapeutic approaches. From retrospective biological cohorts of OS, we analysed by immunohistochemistry the presence of lipopolysaccharide (LPS)-binding protein (LBP) in diagnostic biopsies with local disease and compared their level of infiltration to patients suffering from metastatic status. LBP is considered as a marker of LPS exposure and can indirectly reflect the presence of Gram-negative microbiota. LBP were detected in the cytoplasm of OS cells as well as in tumour-associated macrophage. Tumour samples of patients with local disease were significantly enriched in LBP compared to tumour tissues of patients with metastatic status. Lung metastatic tissues showed similar level of LBP compared to paired primary tumours. Overall, this study strongly suggests the presence of Gram-negative bacteria in OS tissues and demonstrated their significant differential level according the metastatic status. This tumour-associated microbiome may help in the conceptualisation of new therapeutic approach to trigger efficient therapeutic responses against cancer.

Engineering Novel 3D Models to Recreate High-Grade Osteosarcoma and its Immune and Extracellular Matrix Microenvironment

Osteosarcoma (OS) is the most common primary bone cancer, where the overall 5-year surviving rate is below 20% in resistant forms. Accelerating cures for those poor outcome patients remains a challenge. Nevertheless, several studies of agents targeting abnormal cancerous pathways have yielded disappointing results when translated into clinic because of the lack of accurate OS preclinical modeling. So, any effort to design preclinical drug testing may consider all inter-, intra-, and extra-tumoral heterogeneities throughout models mimicking extracellular and immune microenvironment. Therefore, the bioengineering of patient-derived models reproducing the OS heterogeneity, the interaction with tumor-associated macrophages (TAMs), and the modulation of oxygen concentrations additionally to recreation of bone scaffold is proposed here. Eight 2D preclinical models mimicking several OS clinical situations and their TAMs in hypoxic conditions are developed first and, subsequently, the paired 3D models faithfully preserving histological and biological characteristics are generated. It is possible to shape reproducibly M2-like macrophages cultured with all OS patient-derived cell lines in both dimensions. The final 3D models pooling all heterogeneity features are providing accurate proliferation and migration data to understand the mechanisms involved in OS and immune cells/biomatrix interactions and sustained such that engineered 3D preclinical systems will improve personalized medicine.

FN1 overexpression is correlated with unfavorable prognosis and immune infiltrates in breast cancer

Objective: To investigate the correlation of fibronectin 1 (FN1) expression with prognosis and tumor-infiltrating immune cells in breast cancer (BRCA).

Methods: FN1 mRNA and protein expressions were analyzed through Tumor Immune Estimation Resource (TIMER), Gene Set Cancer Analysis (GSCA), Human Protein Atlas (HPA) databases, and immunohistochemical analysis. The clinicopathological characteristics and genetic factors affecting the FN1 mRNA expression were assessed by various public databases. Then, we analyzed the prognostic value of FN1 in BRCA by Kaplan-Meier plotter, receiver operating characteristic, and Cox regression analyses. Further, the UCSC Xena database was used to retrieve TCGA-BRCA expression profiles for functional enrichment analysis and immune cell infiltration analysis. The potential drugs for the BRCA patients with high- FN1 expression were identified using the connectivity map analysis.

Results: FN1 was upregulated in BRCA tissues compared with normal tissues. High FN1 mRNA expression was correlated with poor clinical outcomes and had good performance in predicting the survival status of BRCA patients. Further, Cox regression analysis showed that FN1 was an independent prognostic factor for predicting the overall survival of patients with BRCA. Moreover, hypermethylation of FN1 contributed to a better prognosis for BRCA patients. Functional enrichment analyses revealed the ECM-receptor interaction pathway and focal adhesion as the common pathways. Moreover, FN1 showed a significant association with tumor-infiltrating immune cells and immune checkpoint inhibitors. Several drugs such as telmisartan, malotilate, and seocalcitol may have therapeutic effects in BRCA patients with high FN1 expression.

Conclusion: FN1 might serve as a novel prognostic biomarker and a novel therapeutic target for BRCA. Besides, the association of FN1 with immune cells and immune checkpoint inhibitors may provide assistance for BRCA treatment.

Doxycycline inhibits the progression of metastases in early-stage osteosarcoma by downregulating the expression of MMPs, VEGF and ezrin at primary sites

INTRODUCTION

Osteosarcoma (OS) is the most common primary osseous malignant tumour, with high propensity to metastasise in lungs. Pulmonary micro-metastases are present in up to 80% of patients at initial diagnosis and they are associated with significantly worse prognosis. Doxycycline (Dox) is a synthetic tetracycline that has been shown to have anti-cancer properties in vitro and in vivo, and inhibit angiogenesis - effects that may prove beneficial for several types of cancer. The aim of the present work was to study how Dox affects OS cell growth in vitro and in vivo and OS-driven pulmonary metastasis in vivo.

METHODS

In vitro, the effect of Dox was measured in MG-63 and 143B human OS cell viability, apoptosis, invasion and migration. In vivo, highly metastatic 143B cells were orthotopically implanted into the tibia of SCID mice. The tumour growth and pulmonary metastases between Dox treated and untreated, non-amputated and early amputated xenografts were examined.

RESULTS

In vitro, Dox decreased viability, inhibited invasion, migration, and induced the apoptosis of OS cells. In vivo, Dox significantly enhanced tumour necrosis at primary OS sites, similarly to its in vitro effect, and downregulated the expression of Ki67, MMP2, MMP9, VEGFA and ezrin. It also decreased circulating VEGFA and MMP9 protein levels, in line with the decreased metastatic burden in Dox-treated mice (non-amputated and early-amputated).

CONCLUSIONS

Reprofiling of Dox can prevent the evolvement of pulmonary micro-metastases to clinically detectable macro-metastases and suppress the lethal progress of OS by inhibiting the expression of MMPs, VEGFA and ezrin at primary sites.

Immune Microenvironment in Osteosarcoma: Components, Therapeutic Strategies and Clinical Applications

Osteosarcoma is a primary malignant tumor that tends to threaten children and adolescents, and the 5-year event-free survival rate has not improved significantly in the past three decades, bringing grief and economic burden to patients and society. To date, the genetic background and oncogenesis mechanisms of osteosarcoma remain unclear, impeding further research. The tumor immune microenvironment has become a recent research hot spot, providing novel but valuable insight into tumor heterogeneity and multifaceted mechanisms of tumor progression and metastasis. However, the immune microenvironment in osteosarcoma has been vigorously discussed, and the landscape of immune and non-immune component infiltration has been intensively investigated. Here, we summarize the current knowledge of the classification, features, and functions of the main infiltrating cells, complement system, and exosomes in the osteosarcoma immune microenvironment. In each section, we also highlight the complex crosstalk network among them and the corresponding potential therapeutic strategies and clinical applications to deepen our understanding of osteosarcoma and provide a reference for imminent effective therapies with reduced adverse effects.

Macrophage circadian rhythms are differentially affected based on stimuli

Macrophages are white blood cells that play disparate roles in homeostasis and immune responses. They can reprogram their phenotypes to pro-inflammatory (M1) or anti-inflammatory (M2) states in response to their environment. About 8-15% of the macrophage transcriptome has circadian oscillations, including genes closely related to their functioning. As circadian rhythms are associated with cellular phenotypes, we hypothesized that polarization of macrophages to opposing subtypes might differently affect their circadian rhythms. We tracked circadian rhythms in RAW 264.7 macrophages using luminescent reporters. Cells were stably transfected with Bmal1:luc and Per2:luc reporters, representing positive and negative components of the molecular clock. Strength of rhythmicity, periods and amplitudes of time series were assessed using multiple approaches. M1 polarization decreased amplitudes and rhythmicities of Bmal1:luc and Per2:luc, but did not significantly affect periods, while M2 polarization increased periods but caused no substantial alterations to amplitudes or rhythmicity. As macrophage phenotypes are also altered in the presence of cancer cells, we tested circadian effects of conditioned media from mouse breast cancer cells. Media from highly aggressive 4T1 cells caused loss of rhythmicity, while media from less aggressive EMT6 cells yielded no changes. As macrophages play roles in tumors, and oncogenic features are associated with circadian rhythms, we tested whether conditioned media from macrophages could alter circadian rhythms of cancer cells. Conditioned media from RAW 264.7 cells resulted in lower rhythmicities and periods, but higher amplitudes in human osteosarcoma, U2OS-Per2:luc cells. We show that phenotypic changes in macrophages result in altered circadian characteristics and suggest that there is an association between circadian rhythms and macrophage polarization state. Additionally, our data demonstrate that macrophages treated with breast cancer-conditioned media have circadian phenotypes similar to those of the M1 subtype, and cancer cells treated with macrophage-conditioned media have circadian alterations, providing insight to another level of cross-talk between macrophages and cancer.

The Cellular Tumor Immune Microenvironment of Childhood Solid Cancers: Informing More Effective Immunotherapies

Common pediatric solid cancers fail to respond to standard immuno-oncology agents relying on preexisting adaptive antitumor immune responses. The adoptive transfer of tumor-antigen specific T cells, such as CAR-gene modified T cells, is an attractive strategy, but its efficacy has been limited. Evidence is accumulating that local barriers in the tumor microenvironment prevent the infiltration of T cells and impede therapeutic immune responses. A thorough understanding of the components of the functional compartment of the tumor microenvironment and their interaction could inform effective combination therapies and novel engineered therapeutics, driving immunotherapy towards its full potential in pediatric patients. This review summarizes current knowledge on the cellular composition and significance of the tumor microenvironment in common extracranial solid cancers of childhood and adolescence, such as embryonal tumors and bone and soft tissue sarcomas, with a focus on myeloid cell populations that are often present in abundance in these tumors. Strategies to (co)target immunosuppressive myeloid cell populations with pharmacological anticancer agents and with selective antagonists are presented, as well as novel concepts aiming to employ myeloid cells to cooperate with antitumor T cell responses.

Together Intra-Tumor Hypoxia and Macrophagic Immunity Are Driven Worst Outcome in Pediatric High-Grade Osteosarcomas

Simple Summary

Radiological and immunohistochemical data were correlated with the outcome in a retrospective monocentric cohort of 30 pediatric osteosarcomas (OTS). A necrotic volume of more than 50 cm³ at diagnosis was significantly linked to a worse overall survival (OS). Regarding immunohistochemical analyses, an overexpression of hypoxic markers, such as HIF-1α and anhydrase carbonic IX (CAIX), was significantly linked to a worse OS, while pS6-RP hyperexpression was correlated with a better survival. We also featured that CD68 positive cells, representative of macrophagic M1 polarization, were mostly associated with HIF-1α and CAIX hyperexpressions and that M2-like polarization, mostly related to CD163 positivity, was correlated to mTor activation. These findings, involving clinical, radiological and biology data, allowed us to hypothesize a dual signature association ready to use routinely in future protocols.

Abstract

Background: Osteosarcomas (OTS) represent the most common primary bone cancer diagnosed in adolescents and young adults. Despite remarkable advances, there are no objective molecular or imaging markers able to predict an OTS outcome at diagnosis. Focusing on biomarkers contributing broadly to treatment resistance, we examine the interplay between the tumor-associated macrophages and intra-tumor hypoxia. Methods: Radiological and immunohistochemical (IHC) data were correlated with the outcome in a retrospective and monocentric cohort of 30 pediatric OTS. We studied hypoxic (pS6, phospho-mTor, HIF-1α and carbonic anhydrase IX (CAIX)) and macrophagic (CD68 and CD163) biomarkers. Results: The imaging analyses were based on MRI manual volumetric measures on axial post-contrast T1 weighted images, where, for each tumor, we determined the necrotic volume and its ratio to the entire tumor volume. When they were above 50 cm³ and 20%, respectively, they correlated with a worse overall survival (p = 0.0072 and p = 0.0136, respectively) and event-free survival (p = 0.0059 and p = 0.0143, respectively). IHC assessments enable a significant statistical link between HIF-1α/CAIX hyper-expressions, CD68+ cells and a worse outcome, whereas activation of mTor pathway was linked to a better survival rate and CD163+ cells. Conclusions: This study evidenced the links between hypoxia and immunity in OTS, as their poor outcome may be related to a larger necrotic volume on diagnostic MRI and, in biopsies, to a specific IHC profile.

Metastatic Progression of Osteosarcomas: A Review of Current Knowledge of Environmental versus Oncogenic Drivers

Simple Summary

Osteosarcomas are heterogeneous bone tumors with complex genetic and chromosomic alterations. The numerous patients with metastatic osteosarcoma have a very poor prognosis, and only those who can have full surgical resection of the primary tumor and of all the macro metastasis can survive. Despite the recent improvements in prediction and early detection of metastasis, big efforts are still required to understand the specific mechanisms of osteosarcoma metastatic progression, in order to reveal novel therapeutic targets.

Abstract

Metastases of osteosarcomas are heterogeneous. They may grow simultaneously with the primary tumor, during treatment or shortly after, or a long time after the end of the treatment. They occur mainly in lungs but also in bone and various soft tissues. They can have the same histology as the primary tumor or show a shift towards a different differentiation path. However, the metastatic capacities of osteosarcoma cells can be predicted by gene and microRNA signatures. Despite the identification of numerous metastasis-promoting/predicting factors, there is no efficient therapeutic strategy to reduce the number of patients developing a metastatic disease or to cure these metastatic patients, except surgery. Indeed, these patients are generally resistant to the classical chemo- and to immuno-therapy. Hence, the knowledge of specific mechanisms should be extended to reveal novel therapeutic approaches. Recent studies that used DNA and RNA sequencing technologies highlighted complex relations between primary and secondary tumors. The reported results also supported a hierarchical organization of the tumor cell clones, suggesting that cancer stem cells are involved. Because of their chemoresistance, their plasticity, and their ability to modulate the immune environment, the osteosarcoma stem cells could be important players in the metastatic process.

Osteosarcoma and Metastasis

Osteosarcoma is the most common primary bone malignancy in adolescents. Its high propensity to metastasize is the leading cause for treatment failure and poor prognosis. Although the research of osteosarcoma has greatly expanded in the past decades, the knowledge and new therapy strategies targeting metastatic progression remain sparse. The prognosis of patients with metastasis is still unsatisfactory. There is resonating urgency for a thorough and deeper understanding of molecular mechanisms underlying osteosarcoma to develop innovative therapies targeting metastasis. Toward the goal of elaborating the characteristics and biological behavior of metastatic osteosarcoma, it is essential to combine the diverse investigations that are performed at molecular, cellular, and animal levels from basic research to clinical translation spanning chemical, physical sciences, and biology. This review focuses on the metastatic process, regulatory networks involving key molecules and signaling pathways, the role of microenvironment, osteoclast, angiogenesis, metabolism, immunity, and noncoding RNAs in osteosarcoma metastasis. The aim of this review is to provide an overview of current research advances, with the hope to discovery druggable targets and promising therapy strategies for osteosarcoma metastasis and thus to overcome this clinical impasse.

MCAM is associated with metastasis and poor prognosis in osteosarcoma by modulating tumor cell migration

Background

Although there are standard treatment options for osteosarcoma (OS), the prognoses of patients with OS remain varied. Therefore, it is important to profile OS patients at a high risk of mortality to develop focused interventions. Although tumor biomarkers are closely associated with clinical outcomes, data on prognostic biomarkers for OS remain scarce.

Methods

We collected RNA expression profiles and clinical data of 90 OS patients from the GEO database (dataset GSE21257 and GSE39055) and 96 patients in the TARGET program. The data were analyzed using univariate Kaplan‐Meier survival analysis to screen candidate gene sets that might be associated with OS survival.

Results

Our analysis demonstrated that melanoma cell adhesion molecule (MCAM) was associated with overall survival of patients with OS in the three cohorts. The data showed that MCAM was upregulated in OS patients who had metastases within 5 years compared to those without metastases. GO analysis revealed that genes correlated with MCAM were mainly involved in cell migration and wound healing processes. In addition, wound healing assays and gene set enrichment analysis results from RNA sequencing data of small interfering (si)‐MCAM‐transfected OS cells demonstrated that MCAM modulated tumor cell migration.

Conclusions

Our data demonstrate that MCAM may be a novel prognostic biomarker for OS. MCAM is associated with increased cell migration ability and risk of metastasis, thus leading to poor prognoses in OS patients.

The emerging roles of nitric oxide in ferroptosis and pyroptosis of tumor cells

Tumor cells can develop resistance to cell death which is divided into necrosis and programmed cell death (PCD). PCD, including apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis. Ferroptosis and pyroptosis, two new forms of cell death, have gradually been of interest to researchers. Boosting ferroptosis and pyroptosis of tumor cells could be a potential cancer therapy. Nitric oxide (NO) is a ubiquitous, lipophilic, highly diffusible, free-radical signaling molecule that plays various roles in tumorigenesis. In addition, NO also has regulatory mechanisms through S-nitrosylation that do not depend on the classic NO/sGC/cGMP signaling. The current tumor treatment strategy for NO is to promote cell death through promoting S-nitrosylation-induced apoptosis while multiple drawbacks dampen this tumor therapy. However, numerous studies have suggested that suppression of NO is perceived to active ferroptosis and pyroptosis, which could be a better anti-tumor treatment. In this review, ferroptosis and pyroptosis are described in detail. We summarize that NO influences ferroptosis and pyroptosis and infer that S-nitrosylation mediates ferroptosis- and pyroptosis-related signaling pathways. It could be a potential cancer therapy different from NO-induced apoptosis of tumor cells. Finally, the information shows the drugs that manipulate endogenous production and exogenous delivery of NO to modulate the levels of S-nitrosylation.

Tumor Associated Macrophages: Origin, Recruitment, Phenotypic Diversity, and Targeting

The tumor microenvironment (TME) is known to have a strong influence on tumorigenesis, with various components being involved in tumor suppression and tumor growth. A protumorigenic TME is characterized by an increased infiltration of tumor associated macrophages (TAMs), where their presence is strongly associated with tumor progression, therapy resistance, and poor survival rates. This association between the increased TAMs and poor therapeutic outcomes are stemming an increasing interest in investigating TAMs as a potential therapeutic target in cancer treatment. Prominent mechanisms in targeting TAMs include: blocking recruitment, stimulating repolarization, and depletion methods. For enhancing targeting specificity multiple nanomaterials are currently being explored for the precise delivery of chemotherapeutic cargo, including the conjugation with TAM-targeting peptides. In this paper, we provide a focused literature review of macrophage biology in relation to their role in tumorigenesis. First, we discuss the origin, recruitment mechanisms, and phenotypic diversity of TAMs based on recent investigations in the literature. Then the paper provides a detailed review on the current methods of targeting TAMs, including the use of nanomaterials as novel cancer therapeutics.

The Role of Long Non-Coding RNAs (lncRNAs) in Female Oriented Cancers

Recent advances in molecular biology have discovered the mysterious role of long non-coding RNAs (lncRNAs) as potential biomarkers for cancer diagnosis and targets for advanced cancer therapy. Studies have shown that lncRNAs take part in the incidence and development of cancers in humans. However, previously they were considered as mere RNA noise or transcription byproducts lacking any biological function. In this article, we present a summary of the progress on ascertaining the biological functions of five lncRNAs (HOTAIR, NEAT1, H19, MALAT1, and MEG3) in female-oriented cancers, including breast and gynecological cancers, with the perspective of carcinogenesis, cancer proliferation, and metastasis. We provide the current state of knowledge from the past five years of the literature to discuss the clinical importance of such lncRNAs as therapeutic targets or early diagnostic biomarkers. We reviewed the consequences, either oncogenic or tumor-suppressing features, of their aberrant expression in female-oriented cancers. We tried to explain the established mechanism by which they regulate cancer proliferation and metastasis by competing with miRNAs and other mechanisms involved via regulating genes and signaling pathways. In addition, we revealed the association between stated lncRNAs and chemo-resistance or radio-resistance and their potential clinical applications and future perspectives.

Extracellular Vesicles in Osteosarcoma: Antagonists or Therapeutic Agents?

Osteosarcoma (OS) is a skeletal tumor affecting mainly children and adolescents. The presence of distance metastasis is frequent and it is localized preferentially to the lung, representing the main reason for death among patients. The therapeutic approaches are based on surgery and chemotherapeutics. However, the drug resistance and the side effects associated with the chemotherapy require the identification of new therapeutic approaches. The understanding of the complex biological scenario of the osteosarcoma will open the way for the identification of new targets for its treatment. Recently, a great interest of scientific community is for extracellular vesicles (EVs), that are released in the tumor microenvironment and are important regulators of tumor proliferation and the metastatic process. At the same time, circulating extracellular vesicles can be exploited as diagnostic and prognostic biomarkers, and they can be loaded with drugs as a new therapeutic approach for osteosarcoma patients. Thus, the characterization of OS-related EVs could represent a way to convert these vesicles from antagonists for human health into therapeutic and/or diagnostic agents.