Decoding the Impact of Tumor Microenvironment in Osteosarcoma Progression and Metastasis

3D bioprinted microfluidic based osteosarcoma-on-a chip model as a physiomimetic pre-clinical drug testing platform for anti-cancer drugs

Standard chemotherapeutic regimen for osteosarcoma (OS) treatment often leads to poor therapeutic outcome, primarily due to lack of an adequate representative model reflecting native OS structural and cellular complexity, posing a translational gap. Three-dimensional bioprinting (3D-BP) represents an efficient and advanced technique for precise recapitulation of the structural and cellular complexity of OS tumor microenvironment (TME). In the present study, we employed a dual extrusion-based 3D-BP method to develop an improved in vitro OS model consisting of both tumor and stromal components. Additionally, a human physiomimetic microfluidic bioreactor is introduced to mimic the dynamic TME and provide physiologically relevant mechanical stimulation to the cells. The model named TC-OS Dynamic model, demonstrated close resemblance to native OS-TME, validated by in vitro studies. Continuous media flow provided mechanical stimulation in the form of shear stress, positively influencing the growth and aggressiveness of OS. Further, drug screening with the model anticancer drugs (doxorubicin, cis-platin, sorafenib) demonstrated enhanced sensitivity in TC-OS Dynamic model as compared to TC-OS Static model, emphasizing enhanced mass transfer, availability and distribution of anticancer drug due to continuous media flow. Overall, TC-OS Dynamic model holds significant potential as a platform in future for high throughput pre-clinical screening of anticancer drugs.

Osteosarcoma Exosome Priming of Primary Human Lung Fibroblasts Induces an Immune Modulatory and Protumorigenic Phenotype

SIGNIFICANCE

These findings provide a critical first step in characterizing the capacity of OS-derived exosomes to reprogram primary LFs toward a tumor-promoting inflammatory phenotype in vitro, offering novel molecular targets for the modulation of fibroblasts in the lung microenvironment as potential therapeutic strategies to prevent OS metastasis.

LncRNA SPINT1-AS1 enhances the Warburg effect and promotes the progression of osteosarcoma via the miR-135b-5p/PGAM1 axis

Osteosarcoma (OS) is a malignant bone tumor that originates from interstitial tissues and affects the health of children and adolescents. Long noncoding RNAs (lncRNAs) are an intriguing category of widely distributed endogenous RNAs involved in OS progression, many of which remain functionally uncharacterized. Herein, we observed an increased expression of lncRNA SPINT1-AS1 in OS tissues and cell lines. Further analysis confirmed that SPINT1-AS1 promotes the proliferation and metastasis of OS cells. Moreover, miR-135b-5p was identified as a downstream target of SPINT1-AS1. Through bioinformatics analysis, PGAM1 mRNA was validated as a target of miR-135b-5p via RIP and luciferase reporter assays. SPINT1-AS1 could enhance OS cell proliferation and metastasis by promoting aerobic glycolysis, acting as a ceRNA by binding to miR-135b-5p, thereby increasing PGAM1 expression. Taken together, these results indicate that SPINT1-AS1 functions as a tumor promoter and regulates OS cell progression through the miR-135b-5p/PGAM1 axis.

Targeting myeloid-derived suppressor cells in the tumor microenvironment: potential therapeutic approaches for osteosarcoma

Osteosarcoma is a bone malignancy characterized by strong invasiveness and rapid disease progression. The tumor microenvironment of osteosarcoma contains various types of immune cells, including myeloid-derived suppressor cells, macrophages, T cells, and B cells. Imbalances of these immune cells can promote the proliferation and metastasis of osteosarcoma. Recent studies have indicated a substantial increase in the levels of myeloid-derived suppressor cells, an immune cell associated with immunosuppressive and pro-cancer effects, in the peripheral blood of patients with osteosarcoma. Moreover, the levels of the pro-inflammatory cytokine interleukin 18 are positively correlated with those of myeloid-derived suppressor cells in the peripheral blood of animal models of osteosarcoma. In this review, we explore the function of myeloid-derived suppressor cells in osteosarcoma based on the clinical diagnoses of patients with osteosarcoma and discuss future therapeutic approaches for targeting osteosarcoma. Targeting myeloid-derived suppressor cells represents a promising approach to improving the prognosis and survival rates of patients with osteosarcoma.

Integrated analysis of single-cell and bulk transcriptomics reveals cellular subtypes and molecular features associated with osteosarcoma prognosis

BACKGROUND

Osteosarcoma (OS) is the most common primary bone malignancy with variable molecular biology and prognosis. However, our understanding of the association between cell types and OS progression remains poor.

METHODS

We generated a human OS cell atlas by integrating over 110,000 single cells from 17 samples. Multiple machine learning algorithms were applied to develop tumor purity prediction models based on transcriptomic profile of OS. The Scissor algorithm and gene enrichment analyses were conducted to delve into cell-intrinsic molecular characteristics linked to OS prognosis. Moreover, the study investigated the impact of ATF6α in OS aggressiveness through genetic and pharmacological loss of function analyses. Lastly, the CellChat algorithm was employed to investigate cell-cell communications.

RESULTS

Utilizing the high-quality human OS cell atlas, we identified tumor purity as a prognostic indicator and developed a robust tumor purity prediction model. We respectively delineated cancer cell- and immune cell-intrinsic molecular characteristics associated with OS prognosis at single-cell resolution. Interestingly, tumor cells with activated unfolded protein response (UPR) pathway were significantly associated with disease aggressiveness. Notably, ATF6α emerged as the top-activated transcription factor for this tumor subcluster. Subsequently, we confirmed that ATF6α was markedly associated with OS progression, while both genetic and pharmacological inhibition of ATF6α impaired the survival of HOS cells. Lastly, we depicted the landscape of signal crosstalk between the UPR-related subcluster and other cell types within the tumor microenvironment.

CONCLUSION

In summary, our work provides novel insights into the molecular biology of OS, and offers valuable resource for OS biomarker discovery and treatment strategy development.

Cellular senescence in the tumor with a bone niche microenvironment: friend or foe?

Cellular senescence is understood to be a biological process that is defined as irreversible growth arrest and was originally recognized as a tumor-suppressive mechanism that prevents further propagation of damaged cells. More recently, cellular senescence has been shown to have a dual role in prevention and tumor promotion. Senescent cells carry a senescence-associated secretory phenotype (SASP), which is altered by secretory factors including pro-inflammatory cytokines, chemokines, and other proteases, leading to the alteration of the tissue microenvironment. Though senescence would eventually halt the growth of cancerous potential cells, SASP contributes to the tumor environment by promoting inflammation, matrix remodeling, and tumor cell invasion. The paradox of tumor prevention/promotion is particularly relevant to the bone niche tumor microenvironment, where longer-lasting, chronic inflammation promotes tumor formation. Insights into a mechanistic understanding of cellular senescence and SASP provide the basis for targeted therapies, such as senolytics, which aim to eliminate senescent cells, or SASP inhibitors, which would eliminate the tumor-promoting effects of senescence. These therapeutic interventions offer significant clinical implications for treating cancer and healthy aging.

Immune-related glycosylation genes based classification predicts prognosis and therapy options of osteosarcoma

Osteosarcoma is the most common primary bone malignancy, with a very poor prognosis. Aberrant glycosylation is close involvement in osteosarcoma. Accordingly, this study aimed at investigating the role of glycosylation genes in the prognosis and therapy options of osteosarcoma. The microenvironment of osteosarcoma was assessed using estimate algorithm. A total of 20 immune-related glycosylation genes (IRGGs) was identified using Pearson correlation analysis. Accordingly, osteosarcoma patients were divided into C1 and C2 type using consensus clustering. Multiple algorithms (Xcell, MCP-counter, ssGSEA, epic, quantiseq), cancer immune cycle analysis, and GSVA were applied to estimate the immune, molecule and metabolism characteristics of osteosarcoma, indicating that C1 type was featured with high immune infiltration, high glycosylation, enriched MEK signaling, and good prognosis, while C2 type was characterized by more metastasis, enriched immunotherapy-positive gene signatures, high tumor mutation burden, and poor prognosis. Results from TIDE algorithm and immunotherapy datasets suggested the C2 type's preference of immune checkpoint inhibitors (ICIs), while data of GDSC, CMap analysis and cell experiments indicated that C1 type was sensitivity to MEK inhibitor PD0325901. In addition, univariate Cox and Lasso analysis was combined to establish an IRGGs' risk score containing 6 genes (B3GNT8, FUT7, GAL3ST4, GALNT14, HS3ST2, and MFNG). The data of DCA and ROC indicated its well prediction of prognosis in osteosarcoma. Finally, cellular location analysis showed that the 6 genes not only distributed in tumor cells but also in immune cells. In summary, the classification and risk score based on IRGGs effectively predicted the prognosis and therapy options of osteosarcoma. Further studies on IRGGs may contribute to the understanding of cancer immunity in osteosarcoma.

Recent advances in nanoagents delivery system-based phototherapy for osteosarcoma treatment

Osteosarcoma (OS) is a prevalent and highly malignant bone tumor, characterized by its aggressive nature, invasiveness, and rapid progression, contributing to a high mortality rate, particularly among adolescents. Traditional treatment modalities, including surgical resection, radiotherapy, and chemotherapy, face significant challenges, especially in addressing chemotherapy resistance and managing postoperative recurrence and metastasis. Phototherapy (PT), encompassing photodynamic therapy (PDT) and photothermal therapy (PTT), offers unique advantages such as low toxicity, minimal drug resistance, selective destruction, and temporal control, making it a promising approach for the clinical treatment of various malignant tumors. Constructing multifunctional delivery systems presents an opportunity to effectively combine tumor PDT, PTT, and chemotherapy, creating a synergistic anti-tumor effect. This review aims to consolidate the progress in the application of novel delivery system-mediated phototherapy in osteosarcoma. By summarizing advancements in this field, the objective is to propose a rational combination therapy involving targeted delivery systems and phototherapy for tumors, thereby expanding treatment options and enhancing the prognosis for osteosarcoma patients. In conclusion, the integration of innovative delivery systems with phototherapy represents a promising avenue in osteosarcoma treatment, offering a comprehensive approach to overcome challenges associated with conventional treatments and improve patient outcomes.

CD47 in Osteosarcoma: Correlation with Metastasis and Macrophage-Mediated Phagocytosis

CD47 is expressed on cell surfaces and acts as a "don't eat me" signal by interacting with signal-regulatory protein-α on the macrophage surface. Some cancer cells express CD47 protein and can evade macrophage phagocytosis. Herein, we evaluated the feasibility of targeting CD47 for osteosarcoma by analyzing its expression patterns, clinicopathological correlations, and immunotherapeutic potential. We performed a retrospective analysis on 24 biopsy samples from patients with osteosarcoma to investigate correlations between CD47 protein positivity and clinicopathological characteristics. CD47 protein expression was detected in 20.8% of the biopsy samples. CD47 positivity correlated with metastasis at diagnosis. Patients with CD47-positive tumors were older than those with CD47-negative tumors. However, CD47 protein expression was not associated with sex, tumor size, or histologic response to preoperative chemotherapy. In vitro, CD47 antibody (B6H12) did not affect osteosarcoma cell viability or apoptosis. In a wound-healing assay, CD47 inhibited the migration of osteosarcoma cells. Differentiated macrophages exhibited higher phagocytic activity against osteosarcoma cells when pretreated with B6H12 compared with the isotype control. Our preliminary data suggest a possible interaction between CD47 protein and macrophage phagocytosis in osteosarcoma metastasis. A better understanding of the role of CD47 is necessary to develop an innovative immunotherapeutic approach against osteosarcoma.

The role of neutrophils in osteosarcoma: insights from laboratory to clinic

Osteosarcoma, a highly aggressive malignant bone tumor, is significantly influenced by the intricate interactions within its tumor microenvironment (TME), particularly involving neutrophils. This review delineates the multifaceted roles of neutrophils, including tumor-associated neutrophils (TANs) and neutrophil extracellular traps (NETs), in osteosarcoma's pathogenesis. TANs exhibit both pro- and anti-tumor phenotypes, modulating tumor growth and immune evasion, while NETs facilitate tumor cell adhesion, migration, and immunosuppression. Clinically, neutrophil-related markers such as the neutrophil-to-lymphocyte ratio (NLR) predict patient outcomes, highlighting the potential for neutrophil-targeted therapies. Unraveling these complex interactions is crucial for developing novel treatment strategies that harness the TME to improve osteosarcoma management.

Spatial multiplexed immunofluorescence analysis reveals coordinated cellular networks associated with overall survival in metastatic osteosarcoma

Patients diagnosed with advanced osteosarcoma, often in the form of lung metastases, have abysmal five-year overall survival rates. The complexity of the osteosarcoma immune tumor microenvironment has been implicated in clinical trial failures of various immunotherapies. The purpose of this exploratory study was to spatially characterize the immune tumor microenvironment of metastatic osteosarcoma lung specimens. Knowledge of the coordinating cellular networks within these tissues could then lead to improved outcomes when utilizing immunotherapy for treatment of this disease. Importantly, various cell types, interactions, and cellular neighborhoods were associated with five-year survival status. Of note, increases in cellular interactions between T lymphocytes, positive for programmed cell death protein 1, and myeloid-derived suppressor cells were observed in the 5-year deceased cohort. Additionally, cellular neighborhood analysis identified an Immune-Cold Parenchyma cellular neighborhood, also associated with worse 5-year survival. Finally, the Osteosarcoma Spatial Score, which approximates effector immune activity in the immune tumor microenvironment through the spatial proximity of immune and tumor cells, was increased within 5-year survivors, suggesting improved effector signaling in this patient cohort. Ultimately, these data represent a robust spatial multiplexed immunofluorescence analysis of the metastatic osteosarcoma immune tumor microenvironment. Various communication networks, and their association with survival, were described. In the future, identification of these networks may suggest the use of specific, combinatory immunotherapeutic strategies for improved anti-tumor immune responses and outcomes in osteosarcoma.

Single-cell RNA sequencing reveals the communications between tumor microenvironment components and tumor metastasis in osteosarcoma

Introduction

Osteosarcoma is a common type of bone cancer characterized by a poor prognosis due to its metastatic nature. The tumor microenvironment (TME) plays a critical role in tumor metastasis and therapy response. Therefore, our study aims to explore the metastatic mechanism of osteosarcoma, potentially opening new avenues for cancer treatment.

Methods

In this study, we collected data from the GSE152048, GSE14359, and GSE49003 datasets. Differentially expressed genes (DEGs) were identified in osteosarcoma cases with primary and metastatic features using R software and the limma package. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to investigate metastasis-related genes. A protein-protein interaction (PPI) network was established using the STRING database to further analyze these metastasis-associated genes. The abundances of different cell types with a mixed cell population were estimated using the CIBERSORT approach. The scRNA-seq data were analyzed by the Seurat package in R software, and intercellular communications were elucidated using the CellChat R package.

Results

In this study, 92 DEGs related to metastasis were identified, including 41 upregulated and 51 downregulated genes in both the GSE14359 and GSE49003 datasets. Metastasis-associated pathways were identified, including those involving the cyclin-dependent protein kinase holoenzyme complex, transferase complex, transferring phosphorus-containing groups, SCF ubiquitin ligase complex, and the serine/threonine protein kinase complex. KEGG and PPI network analyses revealed 15 hub genes, including Skp2, KIF20A, CCNF, TROAP, PHB, CKS1B, MCM3, CCNA2, TRIP13, CENPM, Hsp90AB1, JUN, CKS2, TK1, and KIF4A. Skp2 has been known as an E3 ubiquitin ligase involved in osteosarcoma progression. The proportion of CD8+ T cells was found to be higher in metastatic osteosarcoma tissues, and high expression of PHB was associated with a favorable prognosis in osteosarcoma patients. Additionally, 23 cell clusters were classified into eight cell types, including chondrocytes, MSC, T cells, monocytes, tissue stem cells, neurons, endothelial cells, and macrophages. The 15 hub genes were expressed across various cell types, and interactions between different cell types were observed.

Conclusion

Our study reveals the intricate communication between tumor microenvironment components and tumor metastasis in osteosarcoma.

The sEVs miR-487a/Notch2/GATA3 axis promotes osteosarcoma lung metastasis by inducing macrophage polarization toward the M2-subtype

Small extracellular vesicles (sEVs) are important mediators of intercellular communication between tumor cells and their surrounding environment. Furthermore, the mechanisms by which miRNAs carried in tumor sEVs regulate macrophage polarization remain largely unknown. To concentrate sEVs, we used the traditional ultracentrifugation method. Western blot, NanoSight, and transmission electron microscopy were used to identify sEVs. To determine the function of sEVs-miR-487a, we conducted in vivo and in vitro investigations. The intercellular communication mechanism between osteosarcoma cells and M2 macrophages, mediated by sEVs carrying miR-487a, was validated using luciferase reporter assays, transwell assays, and Western blot analysis. In vitro, sEVs enriched in miR-487a and delivered miR-487a to macrophages, promoting macrophage polarization toward an M2-like type, which promotes proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. In vivo, sEVs enriched in miR-487a facilitate lung metastasis of osteosarcoma. Moreover, plasma miR-487a in sEVs was shown to be a potential biomarker applicable for osteosarcoma diagnosis. In summary, miR-487a derived from osteosarcoma cells can be transferred to macrophages via sEVs, then promote macrophage polarization towards an M2-like type by targeting Notch2 and activating the GATA3 pathway. In a feedback loop, the activation of macrophages accelerates epithelial-mesenchymal transition (EMT), which in turn promotes the migration, invasion, and lung metastasis of osteosarcoma cells. This reciprocal interaction between activated macrophages and osteosarcoma cells contributes to the progression of the disease. Our data demonstrate a new mechanism that osteosarcoma tumor cells derived exosomal-miR-487a which is involved in osteosarcoma development by regulating macrophage polarization in tumor microenvironment (TME).

Immunotherapy Innovations in the Fight against Osteosarcoma: Emerging Strategies and Promising Progress

Immunosuppressive elements within the tumor microenvironment are the primary drivers of tumorigenesis and malignant advancement. The presence, as well as the crosstalk between myeloid-derived suppressor cells (MDSCs), osteosarcoma-associated macrophages (OS-Ms), regulatory T cells (Tregs), and endothelial cells (ECs) with osteosarcoma cells cause the poor prognosis of OS. In addition, the consequent immunosuppressive factors favor the loss of treatment potential. Nanoparticles offer a means to dynamically and locally manipulate immuno-nanoparticles, which present a promising strategy for transforming OS-TME. Additionally, chimeric antigen receptor (CAR) technology is effective in combating OS. This review summarizes the essential mechanisms of immunosuppressive cells in the OS-TME and the current immune-associated strategies. The last part highlights the limitations of existing therapies and offers insights into future research directions.

IL-1 Family Members in Bone Sarcomas

IL-1 family members have multiple pleiotropic functions affecting various tissues and cells, including the regulation of the immune response, hematopoietic homeostasis, bone remodeling, neuronal physiology, and synaptic plasticity. Many of these activities are involved in various pathological processes and immunological disorders, including tumor initiation and progression. Indeed, IL-1 family members have been described to contribute to shaping the tumor microenvironment (TME), determining immune evasion and drug resistance, and to sustain tumor aggressiveness and metastasis. This review addresses the role of IL-1 family members in bone sarcomas, particularly the highly metastatic osteosarcoma (OS) and Ewing sarcoma (EWS), and discusses the IL-1-family-related mechanisms that play a role in bone metastasis development. We also consider the therapeutic implications of targeting IL-1 family members, which have been proposed as (i) relevant targets for anti-tumor and anti-metastatic drugs; (ii) immune checkpoints for immune suppression; and (iii) potential antigens for immunotherapy.