An update on emerging drugs in osteosarcoma: towards tailored therapies?

The emerging role of lactate in tumor microenvironment and its clinical relevance

In recent years, the significant impact of lactate in the tumor microenvironment has been greatly documented. Acting not only as an energy substance in tumor metabolism, lactate is also an imperative signaling molecule. It plays key roles in metabolic remodeling, protein lactylation, immunosuppression, drug resistance, epigenetics and tumor metastasis, which has a tight relation with cancer patients' poor prognosis. This review illustrates the roles lactate plays in different aspects of tumor progression and drug resistance. From the comprehensive effects that lactate has on tumor metabolism and tumor immunity, the therapeutic targets related to it are expected to bring new hope for cancer therapy.

Bioinformatics analysis and validation of mesenchymal stem cells related gene MT1G in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a primary malignant bone tumor arising from mesenchymal cells. The standard clinical treatment for OS involves extensive tumor resection combined with neoadjuvant chemotherapy or radiotherapy. OS's invasiveness, lung metastasis, and drug resistance contribute to a low cure rate and poor prognosis with this treatment. Metallothionein 1G (MT1G), observed in various cancers, may serve as a potential therapeutic target for OS.

METHODS

OS samples in GSE33382 and TARGET datasets were selected as the test cohorts. As the external validation cohort, 13 OS tissues and 13 adjacent cancerous tissues from The Second Affiliated Hospital of Nanchang University were collected. Patients with OS were divided into high and low MT1G mRNA-expression groups; differentially expressed genes (DEGs) were identified as MT1G-related genes. The biological function of MT1G was annotated using Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO) and gene set enrichment analysis (GSEA). Gene expression correlation analysis and competing endogenous RNA (ceRNA) regulatory network construction were used to determine potential biological regulatory relationships of DEGs. Survival analysis assessed the prognostic value of MT1G.

RESULTS

MT1G expression increased in OS samples and presented higher in metastatic OS compared with non-metastatic OS. Functional analyses indicated that MT1G was mainly associated with spliceosome. A ceRNA network with DEGs was constructed. MT1G is an effective biomarker predicting survival and correlated with increased recurrence rates and poorer survival.

CONCLUSIONS

This research identified MT1G as a potential biomarker for OS prognosis, highlighting its potential as a therapy target.

Host-derived growth factors drive ERK phosphorylation and MCL1 expression to promote osteosarcoma cell survival during metastatic lung colonization

PURPOSE

For patients with osteosarcoma, disease-related mortality most often results from lung metastasis-a phenomenon shared with many solid tumors. While established metastatic lesions behave aggressively, very few of the tumor cells that reach the lung will survive. By identifying mechanisms that facilitate survival of disseminated tumor cells, we can develop therapeutic strategies that prevent and treat metastasis.

METHODS

We analyzed single cell RNA-sequencing (scRNAseq) data from murine metastasis-bearing lungs to interrogate changes in both host and tumor cells during colonization. We used these data to elucidate pathways that become activated in cells that survive dissemination and identify candidate host-derived signals that drive activation. We validated these findings through live cell reporter systems, immunocytochemistry, and fluorescent immunohistochemistry. We then validated the functional relevance of key candidates using pharmacologic inhibition in models of metastatic osteosarcoma.

RESULTS

Expression patterns suggest that the MAPK pathway is significantly elevated in early and established metastases. MAPK activity correlates with expression of anti-apoptotic genes, especially MCL1. Niche cells produce growth factors that increase ERK phosphorylation and MCL1 expression in tumor cells. Both early and established metastases are vulnerable to MCL1 inhibition, but not MEK inhibition in vivo. Combining MCL1 inhibition with chemotherapy both prevented colonization and eliminated established metastases in murine models of osteosarcoma.

CONCLUSION

Niche-derived growth factors drive MAPK activity and MCL1 expression in osteosarcoma, promoting metastatic colonization. Although later metastases produce less MCL1, they remain dependent on it. MCL1 is a promising target for clinical trials in both human and canine patients.

Pivotal role of IL-8 derived from the interaction between osteosarcoma and tumor-associated macrophages in osteosarcoma growth and metastasis via the FAK pathway

The prognosis of osteosarcoma (OS) has remained stagnant over the past two decades, requiring the exploration of new therapeutic targets. Cytokines, arising from tumor-associated macrophages (TAMs), a major component of the tumor microenvironment (TME), have garnered attention owing to their impact on tumor growth, invasion, metastasis, and resistance to chemotherapy. Nonetheless, the precise functional role of TAMs in OS progression requires further investigation. In this study, we investigated the interaction between OS and TAMs, as well as the contribution of TAM-produced cytokines to OS advancement. TAMs were observed to be more prevalent in lung metastases compared with that in primary tumors, suggesting their potential support for OS progression. To simulate the TME, OS and TAMs were co-cultured, and the cytokines resulting from this co-culture could stimulate OS proliferation, migration, and invasion. A detailed investigation of cytokines in the co-culture conditioned medium (CM) revealed a substantial increase in IL-8, establishing it as a pivotal cytokine in the process of enhancing OS proliferation, migration, and invasion through the focal adhesion kinase (FAK) pathway. In an in vivo model, co-culture CM promoted OS proliferation and lung metastasis, effects that were mitigated by anti-IL-8 antibodies. Collectively, IL-8, generated within the TME formed by OS and TAMs, accelerates OS proliferation and metastasis via the FAK pathway, thereby positioning IL-8 as a potential novel therapeutic target in OS.

An Overview of Advances in Rare Cancer Diagnosis and Treatment

Cancer stands as the leading global cause of mortality, with rare cancer comprising 230 distinct subtypes characterized by infrequent incidence. Despite the inherent challenges in addressing the diagnosis and treatment of rare cancers due to their low occurrence rates, several biomedical breakthroughs have led to significant advancement in both areas. This review provides a comprehensive overview of state-of-the-art diagnostic techniques that encompass new-generation sequencing and multi-omics, coupled with the integration of artificial intelligence and machine learning, that have revolutionized rare cancer diagnosis. In addition, this review highlights the latest innovations in rare cancer therapeutic options, comprising immunotherapy, targeted therapy, transplantation, and drug combination therapy, that have undergone clinical trials and significantly contribute to the tumor remission and overall survival of rare cancer patients. In this review, we summarize recent breakthroughs and insights in the understanding of rare cancer pathophysiology, diagnosis, and therapeutic modalities, as well as the challenges faced in the development of rare cancer diagnosis data interpretation and drug development.

Fractals in the Neurosciences: A Translational Geographical Approach

The chapter presents three new fractal indices (fractal fragmentation index, fractal tentacularity index, and fractal anisotropy index) and normalized Kolmogorov complexity with proven applicability in geographic research, developed by the authors, and the possibility of their future use in neuroscience. The research demonstrates the relevance of fractal analysis in different fields and the basic concepts and principles of fractal geometry being sufficient for the development of models relevant to the studied reality. Also, the research highlighted the need to continue interdisciplinary research based on known fractal indicators, as well as the development of new analysis methods with the translational potential between fields.

Hurdle or thruster: Glucose metabolism of T cells in anti-tumour immunity

Glucose metabolism is essential for the activation, differentiation and function of T cells and proper glucose metabolism is required to maintain effective T cell immunity. Dysregulation of glucose metabolism is a hallmark of cancer, and the tumour microenvironment (TME2) can create metabolic barriers in T cells that inhibit their anti-tumour immune function. Targeting glucose metabolism is a promising approach to improve the capacity of T cells in the TME. The efficacy of common immunotherapies, such as immune checkpoint inhibitors (ICIs3) and adoptive cell transfer (ACT4), can be limited by T-cell function, and the treatment itself can affect T-cell metabolism. Therefore, understanding the relationship between immunotherapy and T cell glucose metabolism helps to achieve more effective anti-tumour therapy. In this review, we provide an overview of T cell glucose metabolism and how T cell metabolic reprogramming in the TME regulates anti-tumour responses, briefly describe the metabolic patterns of T cells during ICI and ACT therapies, which suggest possible synergistic strategies.

LRPPRC regulates malignant behaviors, protects mitochondrial homeostasis, mitochondrial function in osteosarcoma and derived cancer stem-like cells

BACKGROUND

Leucine-rich pentatricopeptide repeat containing (LRPPRC) is a potential oncogene in multiple tumor types, including lung adenocarcinoma, esophageal squamous cell carcinoma and gastric cancer. LRPPRC exerts its tumor-promoting effects mainly by regulating mitochondrial homeostasis and inducing oxidative stress. However, the exact role and mechanisms by which LRPPRC acts in osteosarcoma and osteosarcoma-derived cancer stem-like cells (CSCs), which potentially critically contribute to recurrence, metastasis and chemoresistance, are still largely unclear.

METHODS

LRPPRC level in osteosarcoma cells and CSCs were detected by western blot. Effects of LRPPRC on CSCs were accessed after LRPPRC knockdown by introducing lentivirus containing shRNA targeting to LRPPRC mRNA.

RESULTS

we found that LRPPRC was highly expressed in several osteosarcoma cell lines and that LRPPRC knockdown inhibited malignant behaviors, including proliferation, invasion, colony formation and tumor formation, in MG63 and U2OS cells. Enriched CSCs derived from MG63 and U2OS cells presented upregulated LRPPRC levels compared to parental cells (PCs), and LRPPRC knockdown markedly decreased the sphere-forming capacity. These findings demonstrate that LRPPRC knockdown decreased stemness in CSCs. Consistent with a previous report, LRPPRC knockdown decreased the expression levels of FOXM1 and its downstream target genes, including PRDX3, MnSOD and catalase, which are responsible for scavenging reactive oxygen species (ROS). Expectedly, LRPPRC knockdown increased the accumulation of ROS in osteosarcoma and osteosarcoma-derived CSCs under hypoxic conditions due to the decrease in ROS scavenging proteins. Moreover, LRPPRC knockdown sensitized osteosarcomas and CSCs against carboplatin, a ROS-inducing chemoagent, and promoted apoptosis. Furthermore, LRPPRC knockdown significantly decreased the mitochondrial membrane potential, disturbed mitochondrial homeostasis and led to mitochondrial dysfunction.

CONCLUSION

Taken together, these findings indicated that LRPPRC exerts critical roles in regulating mitochondrial homeostasis, mitochondrial function and tumorigenesis in osteosarcomas and osteosarcoma-derived CSCs. This suggests that LRPPRC might be a promising therapeutic target for osteosarcomas.

Gossypetin Is a Novel Modulator of Inflammatory Cytokine Production and a Suppressor of Osteosarcoma Cell Growth

Osteosarcoma (OS) is a common childhood sarcoma, and its treatment is hindered by adverse effects, chemoresistance, and recurrence. Interleukin (IL)-6 production by tumors plays a significant role in inflammation, carcinogenesis, and metastasis. This study aimed to investigate the antiproliferative potential of luteolin derivatives in OS and to evaluate interleukin production. MG-63, Saos-2, HOS, and 143B human OS cell lines were incubated with luteolin and eight derivatives containing hydroxy, chlorine, or alkyl substitutions. The cell viability and growth were evaluated in the presence of these compounds. Apoptosis was also examined through the analysis of the Bax expression and caspase-3 activity. Finally, the gossypetin effects were measured regarding the production of proinflammatory cytokines interleukin (IL)-6, IL-1β, and IL-12p70. Our findings show that gossypetin was the most potent compound, with proliferation-suppressing activities that induced a series of critical events, including the inhibition of the cell viability and growth. Apoptosis was associated with enhanced caspase-3 activity and increased Bax expression, indicating the involvement of the intrinsic pathway of apoptosis. Moreover, pre-/co-treatment with gossypetin significantly reduced the autocrine production of proinflammatory cytokines. Further investigation is required; nevertheless, considering the link between inflammation, carcinogenesis, and metastasis in OS, our findings suggest that gossypetin exhibits anti-proliferative and anti-inflammatory properties that are potentially relevant in the clinical context.

Cyclers' kinases in cell division: from molecules to cancer therapy

Faithful eucaryotic cell division requires spatio-temporal orchestration of multiple sequential events. To ensure the dynamic nature of these molecular and morphological transitions, a swift modulation of key regulatory pathways is necessary. The molecular process that most certainly fits this description is phosphorylation, the post-translational modification provided by kinases, that is crucial to allowing the progression of the cell cycle and that culminates with the separation of two identical daughter cells. In detail, from the early stages of the interphase to the cytokinesis, each critical step of this process is tightly regulated by multiple families of kinases including the Cyclin-dependent kinases (CDKs), kinases of the Aurora, Polo, Wee1 families, and many others. While cell-cycle-related CDKs control the timing of the different phases, preventing replication machinery errors, the latter modulate the centrosome cycle and the spindle function, avoiding karyotypic abnormalities typical of chromosome instability. Such chromosomal abnormalities may result from replication stress (RS) and chromosome mis-segregation and are considered a hallmark of poor prognosis, therapeutic resistance, and metastasis in cancer patients. Here, we discuss recent advances in the understanding of how different families of kinases concur to govern cell cycle, preventing RS and mitotic infidelity. Additionally, considering the growing number of clinical trials targeting these molecules, we review to what extent and in which tumor context cell-cycle-related kinases inhibitors are worth exploiting as an effective therapeutic strategy.

Biology of GD2 ganglioside: implications for cancer immunotherapy

Part of the broader glycosphingolipid family, gangliosides are composed of a ceramide bound to a sialic acid-containing glycan chain, and locate at the plasma membrane. Gangliosides are produced through sequential steps of glycosylation and sialylation. This diversity of composition is reflected in differences in expression patterns and functions of the various gangliosides. Ganglioside GD2 designates different subspecies following a basic structure containing three carbohydrate residues and two sialic acids. GD2 expression, usually restrained to limited tissues, is frequently altered in various neuroectoderm-derived cancers. While GD2 is of evident interest, its glycolipid nature has rendered research challenging. Physiological GD2 expression has been linked to developmental processes. Passing this stage, varying levels of GD2, physiologically expressed mainly in the central nervous system, affect composition and formation of membrane microdomains involved in surface receptor signaling. Overexpressed in cancer, GD2 has been shown to enhance cell survival and invasion. Furthermore, binding of antibodies leads to immune-independent cell death mechanisms. In addition, GD2 contributes to T-cell dysfunction, and functions as an immune checkpoint. Given the cancer-associated functions, GD2 has been a source of interest for immunotherapy. As a potential biomarker, methods are being developed to quantify GD2 from patients' samples. In addition, various therapeutic strategies are tested. Based on initial success with antibodies, derivates such as bispecific antibodies and immunocytokines have been developed, engaging patient immune system. Cytotoxic effectors or payloads may be redirected based on anti-GD2 antibodies. Finally, vaccines can be used to mount an immune response in patients. We review here the pertinent biological information on GD2 which may be of use for optimizing current immunotherapeutic strategies.

Vitamin D inhibits osteosarcoma by reprogramming nonsense-mediated RNA decay and SNAI2-mediated epithelial-to-mesenchymal transition

Osteosarcomas are immune-resistant and metastatic as a result of elevated nonsense-mediated RNA decay (NMD), reactive oxygen species (ROS), and epithelial-to-mesenchymal transition (EMT). Although vitamin D has anti-cancer effects, its effectiveness and mechanism of action against osteosarcomas are poorly understood. In this study, we assessed the impact of vitamin D and its receptor (VDR) on NMD-ROS-EMT signaling in in vitro and in vivo osteosarcoma animal models. Initiation of VDR signaling facilitated the enrichment of EMT pathway genes, after which 1,25(OH)2D, the active vitamin D derivative, inhibited the EMT pathway in osteosarcoma subtypes. The ligand-bound VDR directly downregulated the EMT inducer SNAI2, differentiating highly metastatic from low metastatic subtypes and 1,25(OH)2D sensitivity. Moreover, epigenome-wide motif and putative target gene analysis revealed the VDR's integration with NMD tumorigenic and immunogenic pathways. In an autoregulatory manner, 1,25(OH)2D inhibited NMD machinery genes and upregulated NMD target genes implicated in anti-oncogenic activity, immunorecognition, and cell-to-cell adhesion. Dicer substrate siRNA knockdown of SNAI2 revealed superoxide dismutase 2 (SOD2)-mediated antioxidative responses and 1,25(OH)2D sensitization via non-canonical SOD2 nuclear-to-mitochondrial translocalization leading to overall ROS suppression. In a mouse xenograft metastasis model, the therapeutically relevant vitamin D derivative calcipotriol inhibited osteosarcoma metastasis and tumor growth shown for the first time. Our results uncover novel osteosarcoma-inhibiting mechanisms for vitamin D and calcipotriol that may be translated to human patients.

Self-Renewal and Pluripotency in Osteosarcoma Stem Cells' Chemoresistance: Notch, Hedgehog, and Wnt/β-Catenin Interplay with Embryonic Markers

Osteosarcoma is a highly malignant bone tumor derived from mesenchymal cells that contains self-renewing cancer stem cells (CSCs), which are responsible for tumor progression and chemotherapy resistance. Understanding the signaling pathways that regulate CSC self-renewal and survival is crucial for developing effective therapies. The Notch, Hedgehog, and Wnt/β-Catenin developmental pathways, which are essential for self-renewal and differentiation of normal stem cells, have been identified as important regulators of osteosarcoma CSCs and also in the resistance to anticancer therapies. Targeting these pathways and their interactions with embryonic markers and the tumor microenvironment may be a promising therapeutic strategy to overcome chemoresistance and improve the prognosis for osteosarcoma patients. This review focuses on the role of Notch, Hedgehog, and Wnt/β-Catenin signaling in regulating CSC self-renewal, pluripotency, and chemoresistance, and their potential as targets for anti-cancer therapies. We also discuss the relevance of embryonic markers, including SOX-2, Oct-4, NANOG, and KLF4, in osteosarcoma CSCs and their association with the aforementioned signaling pathways in overcoming drug resistance.

Bad to the Bone: Emerging Approaches to Aggressive Bone Sarcomas

Bone sarcomas are rare heterogeneous tumors that affect patients of all ages including children, adolescent young adults, and older adults. They include many aggressive subtypes and patient groups with poor outcomes, poor access to clinical trials, and lack of defined standard therapeutic strategies. Conventional chondrosarcoma remains a surgical disease, with no defined role for cytotoxic therapy and no approved targeted systemic therapies. Here, we discuss promising novel targets and strategies undergoing evaluation in clinical trials. Multiagent chemotherapy has greatly improved outcomes for patients with Ewing sarcoma (ES) and osteosarcoma, but management of those with high-risk or recurrent disease remains challenging and controversial. We describe the impact of international collaborative trials, such as the rEECur study, that aim to define optimal treatment strategies for those with recurrent, refractory ES, and evidence for high-dose chemotherapy with stem-cell support. We also discuss current and emerging strategies for other small round cell sarcomas, such as CIC-rearranged, BCOR-rearranged tumors, and the evaluation of emerging novel therapeutics and trial designs that may offer a new paradigm to improve survival in these aggressive tumors with notoriously bad (to the bone) outcomes.

Psoralidin inhibits osteosarcoma growth and metastasis by downregulating ITGB1 expression via the FAK and PI3K/Akt signaling pathways

BACKGROUND

Psoralea corylifolia is a medicinal leguminous plant that has long been used to treat various diseases. Psoralidin (PSO) is the main extract compound of P. corylifolia and exhibits antibacterial, antitumor, anti-inflammatory, antioxidant, and other pharmacological activities. PSO has demonstrated inhibitory effects in several cancers; however, its inhibitory effect on osteosarcoma has not been reported. This study aimed to evaluate the inhibitory effect of PSO on osteosarcoma and elucidate the underlying molecular mechanisms.

METHODS

Crystal violet, cell counting kit-8 (CCK8), and 5-Ethynyl-2'-deoxyuridine (EdU) staining assays were used to assess the inhibitory effect of PSO on the proliferation of 143B and MG63 osteosarcoma cells. Wound healing and Transwell assays were conducted to evaluate the effects of PSO on osteosarcoma cell migration and invasion. The cell cycle and apoptosis were analyzed using flow cytometry. To determine the possible molecular mechanisms, RNA-sequencing was performed and protein expression was analyzed by western blotting. The inhibitory effect of PSO on osteosarcoma in vivo was analyzed using a mouse model of orthotopic osteosarcoma and immunohistochemistry.

RESULTS

PSO inhibited osteosarcoma cell proliferation in a concentration-dependent manner, inhibited cell migration and invasion, and induced cell-cycle arrest and apoptosis. Mechanistically, PSO treatment significantly inhibited the focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways by downregulating ITGB1 expression in both MG63 and 143B cells. Furthermore, we demonstrated that PSO restrained osteosarcoma growth in vivo.

CONCLUSION

PSO may suppress osteosarcoma via the FAK and PI3K/Akt signaling pathways by downregulating ITGB1 expression.

Exosomes and osteosarcoma drug resistance

Osteosarcoma (OS) is a primary malignant tumor of bone characterized by the formation of bone tissue or immature bone by tumor cells. Because of its multi-drug resistance, even with the improvement of chemotherapy and the use of targeted drugs, the survival rate of osteosarcoma (OS) is still less than 60%, and it is easy to metastasize, which is a difficulty for many clinicians and researchers. In recent years, with the continuous research on exosomes, it has been found that exosomes play a role in the diagnosis, treatment and chemotherapy resistance of osteosarcoma due to their unique properties. Exosomes can reduce the intracellular accumulation of chemotherapeutic drugs by mediating drug efflux, thus inducing chemotherapeutic resistance in OS cells. Exosomal goods (including miRNA and functional proteins) carried by exosomes also show great potential in affecting the drug resistance of OS. In addition, miRNA carried by exosomes and exosomes exist widely in tumor cells and can reflect the characteristics of parent cells, so it can also be used as a biomarker of OS. At the same time, the development of nanomedicine has given a new hope for the treatment of OS. Exosomes are regarded as good natural nano-carriers by researchers because of their excellent targeted transport capacity and low toxicity, which will play an important role in the field of OS therapy in the future. This paper reviews the internal relationship between exosomes and OS chemotherapy resistance, discusses the broad prospects of exosomes in the field of diagnosis and treatment of OS, and puts forward some suggestions for the study of the mechanism of OS chemotherapy resistance.

Vitamin D inhibits osteosarcoma by reprogramming nonsense-mediated RNA decay and SNAI2-mediated epithelial-to-mesenchymal transition

Osteosarcomas are immune-resistant and metastatic as a result of elevated nonsense-mediated RNA decay (NMD), reactive oxygen species (ROS), and epithelial-to-mesenchymal transition (EMT). Although vitamin D has anti-cancer effects, its effectiveness and mechanism of action against osteosarcomas are poorly understood. In this study, we assessed the impact of vitamin D and its receptor (VDR) on the NMD-ROS-EMT signaling axis in in vitro and in vivo osteosarcoma animal models. Initiation of VDR signaling facilitated the enrichment of EMT pathway genes, after which 1,25(OH) ₂ D, the active vitamin D derivative, inhibited the EMT pathway in osteosarcoma subtypes. The ligand-bound VDR directly downregulated the EMT inducer SNAI2 , differentiating highly metastatic from low metastatic subtypes and 1,25(OH) ₂ D sensitivity. Moreover, epigenome-wide motif and putative target gene analysis revealed the VDR’s integration with NMD tumorigenic and immunogenic pathways. In an autoregulatory manner, 1,25(OH) ₂ D inhibited NMD machinery genes and upregulated NMD target genes implicated in anti-oncogenic activity, immunorecognition, and cell-to-cell adhesion. Dicer substrate siRNA knockdown of SNAI2 revealed superoxide dismutase 2 (SOD2)-mediated antioxidative responses and 1,25(OH) ₂ D sensitization via non-canonical SOD2 nuclear-to-mitochondrial translocalization leading to overall ROS suppression. In a mouse xenograft metastasis model, the therapeutically relevant vitamin D derivative calcipotriol inhibited osteosarcoma metastasis and tumor growth shown for the first time. Our results uncover novel osteosarcoma-inhibiting mechanisms for vitamin D and calcipotriol that may be translated to human patients.

The First-In-Class Anti-AXL×CD3ε Pronectin™-Based Bispecific T-Cell Engager Is Active in Preclinical Models of Human Soft Tissue and Bone Sarcomas

Sarcomas are heterogeneous malignancies with limited therapeutic options and a poor prognosis. We developed an innovative immunotherapeutic agent, a first-in-class Pronectin™-based Bispecific T-Cell Engager (pAXL×CD3ε), for the targeting of AXL, a TAM family tyrosine kinase receptor highly expressed in sarcomas. AXL expression was first analyzed by flow cytometry, qRT-PCR, and Western blot on a panel of sarcoma cell lines. The T-cell-mediated pAXL×CD3ε cytotoxicity against sarcoma cells was investigated by flow cytometry, luminescence assay, and fluorescent microscopy imaging. The activation and degranulation of T cells induced by pAXL×CD3ε were evaluated by flow cytometry. The antitumor activity induced by pAXL×CD3ε in combination with trabectedin was also investigated. In vivo activity studies of pAXL×CD3ε were performed in immunocompromised mice (NSG), engrafted with human sarcoma cells and reconstituted with human peripheral blood mononuclear cells from healthy donors. Most sarcoma cells showed high expression of AXL. pAXL×CD3ε triggered T-lymphocyte activation and induced dose-dependent T-cell-mediated cytotoxicity. The combination of pAXL×CD3ε with trabectedin increased cytotoxicity. pAXL×CD3ε inhibited the in vivo growth of human sarcoma xenografts, increasing the survival of treated mice. Our data demonstrate the antitumor efficacy of pAXL×CD3ε against sarcoma cells, providing a translational framework for the clinical development of pAXL×CD3ε in the treatment of human sarcomas, aggressive and still-incurable malignancies.

Lithium: A Promising Anticancer Agent

Lithium is a therapeutic cation used to treat bipolar disorders but also has some important features as an anti-cancer agent. In this review, we provide a general overview of lithium, from its transport into cells, to its innovative administration forms, and based on genomic, transcriptomic, and proteomic data. Lithium formulations such as lithium acetoacetate (LiAcAc), lithium chloride (LiCl), lithium citrate (Li₃C₆H₅O₇), and lithium carbonate (Li₂CO₃) induce apoptosis, autophagy, and inhibition of tumor growth and also participate in the regulation of tumor proliferation, tumor invasion, and metastasis and cell cycle arrest. Moreover, lithium is synergistic with standard cancer therapies, enhancing their anti-tumor effects. In addition, lithium has a neuroprotective role in cancer patients, by improving their quality of life. Interestingly, nano-sized lithium enhances its anti-tumor activities and protects vital organs from the damage caused by lipid peroxidation during tumor development. However, these potential therapeutic activities of lithium depend on various factors, such as the nature and aggressiveness of the tumor, the type of lithium salt, and its form of administration and dosage. Since lithium has been used to treat bipolar disorder, the current study provides an overview of its role in medicine and how this has changed. This review also highlights the importance of this repurposed drug, which appears to have therapeutic cancer potential, and underlines its molecular mechanisms.

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.

Directionally Sensitive Fractal Radiomics Compatible With Irregularly Shaped Magnetic Resonance Tumor Regions of Interest: Association With Osteosarcoma Chemoresistance

BACKGROUND

Computational analysis of routinely acquired MRI has potential to improve the tumor chemoresistance prediction and to provide decision support in precision medicine, which may extend patient survival. Most radiomic analytical methods are compatible only with rectangular regions of interest (ROIs) and irregular tumor shape is therefore an important limitation. Furthermore, the currently used analytical methods are not directionally sensitive.

PURPOSE

To implement a tumor analysis that is directionally sensitive and compatible with irregularly shaped ROIs.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 54 patients with histopathologic diagnosis of primary osteosarcoma on tubular long bones and with prechemotherapy MRI.

FIELD STRENGTH/SEQUENCE

A 1.5 T, T2-weighted-short-tau-inversion-recovery-fast-spin-echo.

ASSESSMENT

A model to explore associations with osteosarcoma chemo-responsiveness included MRI data obtained before OsteoSa MAP neoadjuvant cytotoxic chemotherapy. Osteosarcoma morphology was analyzed in the MRI data by calculation of the nondirectional two-dimensional (2D) and directional and nondirectional one-dimensional (1D) Higuchi dimensions (Dh). MAP chemotherapy response was assessed by histopathological necrosis.

STATISTICAL TESTS

The area under the receiver operating characteristic (ROC) curve (AUC) evaluated the association of the calculated features with the actual chemoresponsiveness, using tumor histopathological necrosis (95%) as the endpoint. Least absolute shrinkage and selection operator (LASSO) machine learning and multivariable regression were used for feature selection. Significance was set at <0.05.

RESULTS

The nondirectional 1D Dh reached an AUC of 0.88 in association with the 95% tumor necrosis, while the directional 1D analysis along 180 radial lines significantly improved this association according to the Hanley/McNeil test, reaching an AUC of 0.95. The model defined by variable selection using LASSO reached an AUC of 0.98. The directional analysis showed an optimal predictive range between 90° and 97° and revealed structural osteosarcoma anisotropy manifested by its directionally dependent textural properties.

DATA CONCLUSION

Directionally sensitive radiomics had superior predictive performance in comparison to the standard nondirectional image analysis algorithms with AUCs reaching 0.95 and full compatibility with irregularly shaped ROIs.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 1.

Heparin and Heparin-Based Drug Delivery Systems: Pleiotropic Molecular Effects at Multiple Drug Resistance of Osteosarcoma and Immune Cells

One of the main problems of modern health care is the growing number of oncological diseases both in the elderly and young population. Inadequately effective chemotherapy, which remains the main method of cancer control, is largely associated with the emergence of multidrug resistance in tumor cells. The search for new solutions to overcome the resistance of malignant cells to pharmacological agents is being actively pursued. Another serious problem is immunosuppression caused both by the tumor cells themselves and by antitumor drugs. Of great interest in this context is heparin, a biomolecule belonging to the class of glycosaminoglycans and possessing a broad spectrum of biological activity, including immunomodulatory and antitumor properties. In the context of the rapid development of the new field of “osteoimmunology,” which focuses on the collaboration of bone and immune cells, heparin and delivery systems based on it may be of intriguing importance for the oncotherapy of malignant bone tumors. Osteosarcoma is a rare but highly aggressive, chemoresistant malignant tumor that affects young adults and is characterized by constant recurrence and metastasis. This review describes the direct and immune-mediated regulatory effects of heparin and drug delivery systems based on it on the molecular mechanisms of (multiple) drug resistance in (onco) pathological conditions of bone tissue, especially osteosarcoma.

Targeted Delivery of Chemotherapeutic Agents for Osteosarcoma Treatment

Since osteosarcoma (OS) is an aggressive bone cancer with unknown molecular pathways of etiology and pathophysiology, improving patient survival has long been a challenge. The conventional therapy is a complex multidisciplinary management that include radiotherapy, chemotherapy which followed by surgery and then post-operative adjuvant chemotherapy. However, they have severe side effects because the majority of the medicines used have just a minor selectivity for malignant tissue. As a result, treating tumor cells specifically without damaging healthy tissue is currently a primary goal in OS therapy. The coupling of chemotherapeutic drugs with targeting ligands is a unique therapy method for OS that, by active targeting, can overcome the aforementioned hurdles. This review focuses on advances in ligands and chemotherapeutic agents employed in targeted delivery to improve the capacity of active targeting and provide some insight into future therapeutic research for OS.

miR-486-5p expression is regulated by DNA methylation in osteosarcoma

Background

Osteosarcoma is the most common primary malignant tumour of bone occurring in children and young adolescents and is characterised by complex genetic and epigenetic changes. The miRNA miR-486-5p has been shown to be downregulated in osteosarcoma and in cancer in general.

Results

To investigate if the mir-486 locus is epigenetically regulated, we integrated DNA methylation and miR-486-5p expression data using cohorts of osteosarcoma cell lines and patient samples. A CpG island in the promoter of the ANK1 host gene of mir-486 was shown to be highly methylated in osteosarcoma cell lines as determined by methylation-specific PCR and direct bisulfite sequencing. High methylation levels were seen for osteosarcoma patient samples, xenografts and cell lines based on quantitative methylation-specific PCR. 5-Aza-2′-deoxycytidine treatment of osteosarcoma cell lines caused induction of miR-486-5p and ANK1, indicating common epigenetic regulation in osteosarcoma cell lines. When overexpressed, miR-486-5p affected cell morphology.

Conclusions

miR-486-5p represents a highly cancer relevant, epigenetically regulated miRNA in osteosarcoma, and this knowledge contributes to the understanding of osteosarcoma biology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08346-6.

Exosomal Long Non-Coding RNA ANCR Mediates Drug Resistance in Osteosarcoma

Osteosarcoma (OS) is rare cancer with bimodal age distribution with peaks observed in children and young adults. Typically, OS is treated with pre-surgery neoadjuvant therapy, surgical excision, and post-surgery chemotherapy. However, the efficacy of treatment on disease prognosis and objective response is not currently optimal, often resulting in drug resistance; in turn, highlighting the need to understand mechanisms driving resistance to therapy in OS patients. Using Doxycycline (Dox)-sensitive and resistant variants of OS cells lines KHOS and U2OS, we found that the resistant variants KHOS-DR and U2OS-DR have significantly higher in vitro proliferation. Treating the Dox-sensitive KHOS/U2OS cells with exosomes isolated from KHOS-DR/U2OS-DR made them resistant to treatment with Dox in vitro and in vivo and enhanced tumor growth and progression, while decreasing overall survival. Expression of the long non-coding RNA (lncRNA) ANCR was significantly higher in the KHOS-DR and U2OS-DR variants. SiRNA-mediated knockdown of ANCR decreased in vitro proliferation, while increasing sensitivity to Dox treatment in the KHOS-DR/U2OS-DR cells. Expression of the exosomal lncRNA ANCR was critical for drug resistance and OS tumor progression in xenografts and was correlated to resistance to Adriamycin and overall survival is patients with OS. These results establish lncRNA ANCR as a critical mediator of resistance to therapy in OS patients, highlighting it as a potential therapeutic target in OS patients.

Targeting Tumor Glycans for Cancer Therapy: Successes, Limitations, and Perspectives

Simple Summary

Aberrant glycosylation is a common feature of many cancers, and it plays crucial roles in tumor development and biology. Cancer progression can be regulated by several physiopathological processes controlled by glycosylation, such as cell–cell adhesion, cell–matrix interaction, epithelial-to-mesenchymal transition, tumor proliferation, invasion, and metastasis. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs), which are suitable for selective cancer targeting, as well as novel antitumor immunotherapy approaches. This review summarizes the strategies developed in cancer immunotherapy targeting TACAs, analyzing molecular and cellular mechanisms and state-of-the-art methods in clinical oncology.

Abstract

Aberrant glycosylation is a hallmark of cancer and can lead to changes that influence tumor behavior. Glycans can serve as a source of novel clinical biomarker developments, providing a set of specific targets for therapeutic intervention. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs) suitable for selective cancer-targeting therapy. The best characterized TACAs are truncated O-glycans (Tn, TF, and sialyl-Tn antigens), gangliosides (GD2, GD3, GM2, GM3, fucosyl-GM1), globo-serie glycans (Globo-H, SSEA-3, SSEA-4), Lewis antigens, and polysialic acid. In this review, we analyze strategies for cancer immunotherapy targeting TACAs, including different antibody developments, the production of vaccines, and the generation of CAR-T cells. Some approaches have been approved for clinical use, such as anti-GD2 antibodies. Moreover, in terms of the antitumor mechanisms against different TACAs, we show results of selected clinical trials, considering the horizons that have opened up as a result of recent developments in technologies used for cancer control.

Schisandrin B suppresses osteosarcoma lung metastasis in vivo by inhibiting the activation of the Wnt/β‑catenin and PI3K/Akt signaling pathways

Osteosarcoma (OS) is the most common malignant bone tumor worldwide and is associated with a poor prognosis, often being accompanied by lung metastasis at an early stage. At present, there are several side-effects associated with the OS clinical treatment of OS, with the treatment effects often being unsatisfactory. Thus, there is an urgent need for the development of safe and effective novel drugs for the treatment of OS. Schisandrin B (Sch B) has been previously demonstrated to exhibit antitumor properties. The present study was focused on the effects of Sch B on OS cells (143B, MG63, Saos2 and U2OS) in vitro and in vivo, and also on its possible antitumor mechanisms. In cell experiments, it was revealed that Sch B inhibited OS cell proliferation, migration and invasion, and increased OS cell apoptosis. As regards its biosafety, no notable effects of Sch B on the vitality of normal cells were observed. Mechanistically, it was demonstrated that Sch B blocked OS cell proliferation in the G₁ phase. Subsequently, by using established animal models, it was revealed that Sch B significantly inhibited OS growth and lung metastasis in vivo. In summary, the results of the present study revealed that Sch B inhibited OS cell proliferation, migration and invasion, and promoted apoptosis via the inhibition of the Wnt/β-catenin and PI3K/Akt signaling pathways, without causing any noticeable toxic effects on healthy cells at the therapeutic concentrations used. These findings suggest that Sch B has potential for use as a novel agent for the clinical treatment of OS.

15d-PGJ2 Promotes ROS-Dependent Activation of MAPK-Induced Early Apoptosis in Osteosarcoma Cell In Vitro and in an Ex Ovo CAM Assay

Osteosarcoma (OS) is the most common type of bone tumor, and has limited therapy options. 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) has striking anti-tumor effects in various tumors. Here, we investigated molecular mechanisms that mediate anti-tumor effects of 15d-PGJ₂ in different OS cell lines. Human U2-OS and Saos-2 cells were treated with 15d-PGJ₂ and cell survival was measured by MTT assay. Cell proliferation and motility were investigated by scratch assay, the tumorigenic capacity by colony forming assay. Intracellular ROS was estimated by H₂DCFDA. Activation of MAPKs and cytoprotective proteins was detected by immunoblotting. Apoptosis was detected by immunoblotting and Annexin V/PI staining. The ex ovo CAM model was used to study growth capability of grafted 15d-PGJ₂-treated OS cells, followed by immunohistochemistry with hematoxylin/eosin and Ki-67. 15d-PGJ₂ substantially decreased cell viability, colony formation and wound closure capability of OS cells. Non-malignant human osteoblast was less affected by 15d-PGJ₂. 15d-PGJ₂ induced rapid intracellular ROS production and time-dependent activation of MAPKs (pERK1/2, pJNK and pp38). Tempol efficiently inhibited 15d-PGJ₂-induced ERK1/2 activation, while N-acetylcystein and pyrrolidine dithiocarbamate were less effective. Early but weak activation of cytoprotective proteins was overrun by induction of apoptosis. A structural analogue, 9,10-dihydro-15d-PGJ₂, did not show toxic effects in OS cells. In the CAM model, we grafted OS tumors with U2-OS, Saos-2 and MG-63 cells. 15d-PGJ₂ treatment resulted in significant growth inhibition, diminished tumor tissue density, and reduced tumor cell proliferation for all cell lines. Our in vitro and CAM data suggest 15d-PGJ₂ as a promising natural compound to interfere with OS tumor growth.

Bioengineering a humanized 3D tri-culture osteosarcoma model to assess tumor invasiveness and therapy response

To date, anticancer therapies with evidenced efficacy in preclinical models fail during clinical trials. The shortage of robust drug screening platforms that accurately predict patient's response underlie these misleading results. To provide a reliable platform for tumor drug discovery, we herein propose a relevant humanized 3D osteosarcoma (OS) model exploring the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to sustain spheroid growth and invasion. The architecture and synergistic cell-microenvironment interaction of an invading tumor was recapitulated encapsulating spheroids in PLMA hydrogels, alone or co-cultured with osteoblasts and mesenchymal stem cells. The stem cells alignment toward OS spheroid suggested that tumor cells chemotactically attracted the surrounding stromal cells, which supported tumor growth and invasion into the hydrogels. The exposure of established models to doxorubicin revealed an improved drug resistance of PLMA-based models, comparing with scaffold-free spheroids. The proposed OS models highlighted the feasibility of PLMA hydrogels to support tumor invasion and recapitulate tumor-stromal cell crosstalk, demonstrating the potential of this 3D platform for complex tumor modelling. STATEMENT OF SIGNIFICANCE: Cell invasion mechanisms involved in tumor progression have been recapitulated in the field of 3D in vitro modeling, leveraging the great advance in biomimetic materials. In line with the growing interest in human-derived biomaterials, the aim of this study is to explore for the first time the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to develop a humanized 3D osteosarcoma model to assess tumor invasiveness and drug sensitivity. By co-culturing tumor spheroids with human osteoblasts and human mesenchymal stem cells, this study demonstrated the importance of the synergistic tumor cell-microenvironment interaction in tumor growth, invasion and drug resistance. The established 3D osteosarcoma model highlighted the feasibility of PLMA hydrogels as a relevant 3D platform for complex tumor modelling.

Wnt pathway modulators in cancer therapeutics: An update on completed and ongoing clinical trials

Wnt signaling plays an essential role in the initiation and progression of various types of cancer. Besides, the Wnt pathway components have been established as reliable biomarkers and potential targets for cancer therapy. Wnt signaling is categorized into canonical and noncanonical pathways. The canonical pathway is involved in cell survival, proliferation, differentiation and migration, while the noncanonical pathway regulates cell polarity and migration. Apart from its biological role in development and homeostasis, the Wnt pathway has been implicated in several pathological disorders, including cancer. As a result, inhibiting this pathway has been a focus of cancer research with multiple targetable candidates in development. In this review, our focus will be to summarize information about ongoing and completed clinical trials targeting various Wnt pathway components, along with describing current and emerging Wnt targeted therapies. In addition, we will discuss potential opportunities and associated challenges of inhibiting Wnt signaling for cancer therapy.

HER Tyrosine Kinase Family and Rhabdomyosarcoma: Role in Onset and Targeted Therapy

Rhabdomyosarcomas (RMS) are tumors of the skeletal muscle lineage. Two main features allow for distinction between subtypes: morphology and presence/absence of a translocation between the PAX3 (or PAX7) and FOXO1 genes. The two main subtypes are fusion-positive alveolar RMS (ARMS) and fusion-negative embryonal RMS (ERMS). This review will focus on the role of receptor tyrosine kinases of the human epidermal growth factor receptor (EGFR) family that is comprised EGFR itself, HER2, HER3 and HER4 in RMS onset and the potential therapeutic targeting of receptor tyrosine kinases. EGFR is highly expressed by ERMS tumors and cell lines, in some cases contributing to tumor growth. If not mutated, HER2 is not directly involved in control of RMS cell growth but can be expressed at significant levels. A minority of ERMS carries a HER2 mutation with driving activity on tumor growth. HER3 is frequently overexpressed by RMS and can play a role in the residual myogenic differentiation ability and in resistance to signaling-directed therapy. HER family members could be exploited for therapeutic approaches in two ways: blocking the HER member (playing a driving role for tumor growth with antibodies or inhibitors) and targeting expressed HER members to vehiculate toxins or immune effectors.

The inhibitory effect of CTAB on human osteosarcoma through the PI3K/AKT signaling pathway

Osteosarcoma (OS) metastasis and recurrence and multidrug resistance are three major obstacles in the clinic. New highly effective and low toxicity drugs for osteosarcoma are needed. The antitumoral efficacy of cetrimonium bromide (CTAB), a quaternary ammonium compound, is gradually being investigated. The aim of the present study was to investigate the effects of CTAB on OS cells and the underlying mechanisms. CTAB inhibited the proliferation of osteosarcoma cells in a concentration‑ and time‑dependent manner, resulting in cell cycle arrest in G1 phase. CTAB also suppressed the migration and invasion of HOS and MG63 cells at a low concentration without inhibiting the growth of human osteoblasts. Moreover, CTAB promoted caspase‑mediated apoptosis of osteosarcoma cells through the PI3K/AKT cascade, and this effect was accompanied by obvious mitochondrial toxicity. In vivo, CTAB inhibited OS proliferation without inducing organ toxicity. In conclusion, this study reveals that CTAB has an inhibitory effect on OS by suppressing proliferation and metastasis and inducing apoptosis through the PI3K/AKT signaling pathway and identifies CTAB as a potential therapeutic drug.

Drug Resistance in Osteosarcoma: Emerging Biomarkers, Therapeutic Targets and Treatment Strategies

Simple Summary

Despite the adoption of aggressive, multimodal treatment schedules, the cure rate of high-grade osteosarcoma (HGOS) has not significantly improved in the last 30 years. The most relevant problem preventing improvement in HGOS prognosis is drug resistance. Therefore, validated novel biomarkers that help to identify those patients who could benefit from innovative treatment options and the development of drugs enabling personalized therapeutic protocols are necessary. The aim of this review was to give an overview on the most relevant emerging drug resistance-related biomarkers, therapeutic targets and new agents or novel candidate treatment strategies, which have been highlighted and suggested for HGOS to improve the success rate of clinical trials.

Abstract

High-grade osteosarcoma (HGOS), the most common primary malignant tumor of bone, is a highly aggressive neoplasm with a cure rate of approximately 40–50% in unselected patient populations. The major clinical problems opposing the cure of HGOS are the presence of inherent or acquired drug resistance and the development of metastasis. Since the drugs used in first-line chemotherapy protocols for HGOS and clinical outcome have not significantly evolved in the past three decades, there is an urgent need for new therapeutic biomarkers and targeted treatment strategies, which may increase the currently available spectrum of cure modalities. Unresponsive or chemoresistant (refractory) HGOS patients usually encounter a dismal prognosis, mostly because therapeutic options and drugs effective for rescue treatments are scarce. Tailored treatments for different subgroups of HGOS patients stratified according to drug resistance-related biomarkers thus appear as an option that may improve this situation. This review explores drug resistance-related biomarkers, therapeutic targets and new candidate treatment strategies, which have emerged in HGOS. In addition to consolidated biomarkers, specific attention has been paid to the role of non-coding RNAs, tumor-derived extracellular vesicles, and cancer stem cells as contributors to drug resistance in HGOS, in order to highlight new candidate markers and therapeutic targets. The possible use of new non-conventional drugs to overcome the main mechanisms of drug resistance in HGOS are finally discussed.

Knockdown of MCM8 functions as a strategy to inhibit the development and progression of osteosarcoma through regulating CTGF

Osteosarcoma is the most common primary malignant tumor of bone derived from osteoblasts, which is a noteworthy threat to the health of children and adolescents. In this study, we found that MCM8 has significantly higher expression level in osteosarcoma tissues in comparison with normal tissues, which was also correlated with more advanced tumor grade and pathological stage. In agreement with the role of MCM proteins as indicators of cell proliferation, knockdown/overexpression of MCM8 inhibited/promoted osteosarcoma cell proliferation in vitro and tumor growth in vivo. Also, MCM8 knockdown/overexpression was also significantly associated with the promotion/inhibition of cell apoptosis and suppression/promotion of cell migration. More importantly, mechanistic study identified CTGF as a potential downstream target of MCM8, silencing of which could enhance the regulatory effects of MCM8 knockdown and alleviate the effects of MCM8 overexpression on osteosarcoma development. In summary, MCM8/CTGF axis was revealed as critical participant in the development and progression of osteosarcoma and MCM8 may be a promising therapeutic target for osteosarcoma treatment.

Cyclin-dependent kinase 7 (CDK7) is an emerging prognostic biomarker and therapeutic target in osteosarcoma

Background:

Overexpression of cyclin-dependent kinase 7 (CDK7) is a well-known pathogenic feature of various malignancies and a sign of a more dismal prognosis. As relatively little is known about CDK7 in osteosarcoma, we elected to evaluate its expression, prognostic value, and function.

Methods:

We began by analyzing the publicly available data sets on CDK7 expression, including RNA sequencing data from the Therapeutically Applicable Research to Generate Effective Treatments on Osteosarcoma (TARGET-OS) and the Gene Expression database of Normal and Tumor tissues 2 (GENT2). The correlation between patient tissue CDK7 expression and their clinicopathological features and prognosis was assessed via immunohistochemical staining of a unique tissue microarray constructed from osteosarcoma specimens. Furthermore, we analyzed CDK7 expression in osteosarcoma cell lines and tissues by Western blot. CDK7-specific siRNA and a highly-selective CDK7 inhibitor, BS-181, were applied to determine the function of CDK7 on osteosarcoma cell growth and proliferation. In addition, the effect of CDK7 inhibition on clonogenicity was evaluated using a clonogenic assay, and a 3D cell culture model was used to mimic CDK7 effects in an in vivo environment.

Results:

Our results demonstrate that higher CDK7 expression significantly correlates with recurrence, metastasis, and shorter overall survival in osteosarcoma patients. Therapeutically, we show that CDK7 knockdown with siRNA or selective inhibition with BS-181 decreases proliferation and induces apoptosis of osteosarcoma cells.

Conclusion:

This study supports CDK7 overexpression as an independent predictor of poor prognosis and promising therapeutic target for osteosarcoma.

Targeting Drugs Against Fibroblast Growth Factor(s)-Induced Cell Signaling

BACKGROUND

The fibroblast growth factor (FGF) family is comprised of 23 highly regulated monomeric proteins that regulate a plethora of developmental and pathophysiological processes, including tissue repair, wound healing, angiogenesis, and embryonic development. Binding of FGF to fibroblast growth factor receptor (FGFR), a tyrosine kinase receptor, is facilitated by a glycosaminoglycan, heparin. Activated FGFRs phosphorylate the tyrosine kinase residues that mediate induction of downstream signaling pathways, such as RAS-MAPK, PI3K-AKT, PLCγ, and STAT. Dysregulation of the FGF/FGFR signaling occurs frequently in cancer due to gene amplification, FGF activating mutations, chromosomal rearrangements, integration, and oncogenic fusions. Aberrant FGFR signaling also affects organogenesis, embryonic development, tissue homeostasis, and has been associated with cell proliferation, angiogenesis, cancer, and other pathophysiological changes.

OBJECTIVE

This comprehensive review will discuss the biology, chemistry, and functions of FGFs, and its current applications toward wound healing, diabetes, repair and regeneration of tissues, and fatty liver diseases. In addition, specific aberrations in FGFR signaling and drugs that target FGFR and aid in mitigating various disorders, such as cancer, are also discussed in detail.

CONCLUSION

Inhibitors of FGFR signaling are promising drugs in the treatment of several types of cancers. The clinical benefits of FGF/FGFR targeting therapies are impeded due to the activation of other RTK signaling mechanisms or due to the mutations that abolish the drug inhibitory activity on FGFR. Thus, the development of drugs with a different mechanism of action for FGF/FGFR targeting therapies is the recent focus of several preclinical and clinical studies.

Molecular Mechanisms of Hepatoblastoma

Hepatoblastoma (HB) is the predominant primary liver tumor in children. While the prognosis is favorable when the tumor can be resected, the outcome is dismal for patients with progressed HB. Therefore, a better understanding of the molecular mechanisms responsible for HB is imperative for early detection and effective treatment. Sequencing analysis of human HB specimens unraveled the pivotal role of Wnt/β-catenin pathway activation in this disease. Nonetheless, β-catenin activation alone does not suffice to induce HB, implying the need for additional alterations. Perturbations of several pathways, including Hippo, Hedgehog, NRF2/KEAP1, HGF/c-Met, NK-1R/SP, and PI3K/AKT/mTOR cascades and aberrant activation of c-MYC, n-MYC, and EZH2 proto-oncogenes, have been identified in HB, although their role requires additional investigation. Here, we summarize the current knowledge on HB molecular pathogenesis, the relevance of the preclinical findings for the human disease, and the innovative therapeutic strategies that could be beneficial for the treatment of HB patients.

Notch-1 promotes the malignant progression of osteosarcoma through the activation of cell division cycle 20

The molecular mechanism of osteosarcoma (OS) pathogenesis is poorly understood. The Notch signaling pathway has been shown to be critically involved in tumorigenesis, including OS. Therefore, we explored the molecular mechanism by which the Notch-1 signaling pathway is involved in OS progression. Several approaches were carried out to determine the biological function of Notch-1 in OS cells. The MTT results revealed that Notch-1 overexpression increased the viability of OS cells, whereas Notch-1 downregulation reduced cell viability. Consistently, modulation of Notch-1 regulated apoptosis and the migratory and invasive abilities of OS cells. Mechanistic studies showed that Notch-1 overexpression augmented cell division cycle 20 (Cdc20) expression in OS cells. Moreover, overexpression of Cdc20 alleviated the inhibitory effects of Notch-1 downregulation on the viability, migration and invasion of OS cells. Our study offers a promising OS treatment strategy by inhibiting Notch-1.

Strategies to Improve Chimeric Antigen Receptor Therapies for Neuroblastoma

Chimeric antigen receptors (CARs) are among the curative immunotherapeutic approaches that exploit the antigen specificity and cytotoxicity function of potent immune cells against cancers. Neuroblastomas, the most common extracranial pediatric solid tumors with diverse characteristics, could be a promising candidate for using CAR therapies. Several methods harness CAR-modified cells in neuroblastoma to increase therapeutic efficiency, although the assessment has been less successful. Regarding the improvement of CARs, various trials have been launched to overcome insufficient capacity. However, the reasons behind the inadequate response against neuroblastoma of CAR-modified cells are still not well understood. It is essential to update the present state of comprehension of CARs to improve the efficiency of CAR therapies. This review summarizes the crucial features of CARs and their design for neuroblastoma, discusses challenges that impact the outcomes of the immunotherapeutic competence, and focuses on devising strategies currently being investigated to improve the efficacy of CARs for neuroblastoma immunotherapy.

Expression and clinical implications of leucine-rich repeat containing 15 (LRRC15) in osteosarcoma

Leucine-rich repeat containing 15 (LRRC15) is a member of the leucine-rich repeat superfamily that is overexpressed in various cancers and associated with higher tumor grade and aggression. Despite its known tumorigenicity, its roles within osteosarcoma are unknown, prompting us to evaluate its expression and clinical significance within this rare yet aggressive cancer. Western blots showed differential expression of LRRC15 in the osteosarcoma cell lines MNNG/HOS, KHOS, 143B, MG63, Saos-2, and U2OS. We additionally validated this positive expression, as well as sublocalization to the cell membrane, with immunofluorescence. A tissue microarray constructed from 69 osteosarcoma patient tissues was immunohistochemically stained for LRRC15 expression, stratified, and used for clinicopathological analysis. Publicly available databases on LRRC15 expression, including RNA sequencing data from the Therapeutically Applicable Research to Generate Effective Treatments on Osteosarcoma (TARGET-OS) and the Gene Expression database of Normal and Tumor tissues 2 (GENT2) were also analyzed. We found 63 of the 69 (91.3%) patient tissues exhibited some degree of LRRC15 immunostaining, including no staining (6 of 69, 8.7%), 1+ staining (12 of 69, 17.4%), 2+ staining (25 of 69, 36.2%), and 3+ staining (26 of 69, 37.7%). The patients with osteosarcomas having elevated LRRC15 expression demonstrated comparatively increased metastasis, chemoresistance, and shorter 5-year survival rates. Our analysis of the TARGET-OS and GENT2 databases also showed increased LRRC15 gene expression in osteosarcoma. Taken together, our study supports LRRC15 as a prognostic biomarker and emerging therapeutic target in osteosarcoma.

Thiostrepton and miR-216b synergistically promote osteosarcoma cell cytotoxicity and apoptosis by targeting FoxM1

Osteosarcoma is a common primary bone cancer that there are currently no effective treatment strategies for. Forkhead box M1 (FoxM1) is key in the development of osteosarcoma, and microRNA (miR)-216b serves an antitumor role by targeting FoxM1. Moreover, thiostrepton (TST), a natural thiazole antibiotic, induces antitumor effects and specifically targets FoxM1. Therefore, the present study investigated whether thiostrepton and miR-216b synergistically inhibited osteosarcoma cells by targeting FoxM1. The MTT assay, reverse transcription-quantitative PCR, a dual-luciferase reporter assay and flow cytometry were performed. Compared with the human osteoblast cell line hFOB1.19, miR-216b expression was significantly downregulated in the osteosarcoma cell lines U2OS, MG63 and Saos-2. By contrast, FoxM1 expression was significantly upregulated in osteosarcoma cell lines compared with the hFOB1.19 cell line. The results indicated that miR-216b targeted the 3′-untranslated region of FoxM1. Moreover, the results suggested that miR-216b cooperated with TST to decrease cell cytotoxicity and increase cell apoptosis. In addition, miR-216b cooperated with TST to increase Bax expression and decrease Bcl-2 expression. In conclusion, the combination of TST and miR-216b synergistically promoted osteosarcoma cell cytotoxicity and apoptosis by targeting FoxM1. Therefore, the present study suggested that the combination of TST and miR-216b may serve as a promising therapeutic strategy for osteosarcoma.

Targeting Molecular Mechanisms Underlying Treatment Efficacy and Resistance in Osteosarcoma: A Review of Current and Future Strategies

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Due to micrometastatic spread, radical surgery alone rarely results in cure. Introduction of combination chemotherapy in the 1970s, however, dramatically increased overall survival rates from 20% to approximately 70%. Unfortunately, large clinical trials aiming to intensify treatment in the past decades have failed to achieve higher cure rates. In this review, we revisit how the heterogenous nature of osteosarcoma as well as acquired and intrinsic resistance to chemotherapy can account for stagnation in therapy improvement. We summarise current osteosarcoma treatment strategies focusing on molecular determinants of treatment susceptibility and resistance. Understanding therapy susceptibility and resistance provides a basis for rational therapy betterment for both identifying patients that might be cured with less toxic interventions and targeting resistance mechanisms to sensitise resistant osteosarcoma to conventional therapies.

The Landscape of CAR-T Cell Clinical Trials against Solid Tumors-A Comprehensive Overview

Simple Summary

Certain immune cells, namely T cells, of cancer patients can be genetically manipulated to express so-called chimeric antigen receptors (CARs), which enables these cells to kill the tumor cells after recognition by the receptor. This therapy is very successful in the treatment of hematologic tumors such as lymphoma or leukemia. However, tumors growing as a solid mass are less susceptible to this kind of treatment. This review summarizes known data of all clinical trials using this therapy against solid tumors that are registered at clinicaltrials.gov.

Abstract

CAR-T cells showed great potential in the treatment of patients with hematologic tumors. However, the clinical efficacy of CAR-T cells against solid tumors lags behind. To obtain a comprehensive overview of the landscape of CAR-T cell clinical trials against this type of cancer, this review summarizes all the 196 studies registered at clinicaltrials.gov. Special focus is on: (1) geographical distribution; (2) targeted organs, tumor entities, and antigens; (3) CAR transfer methods, CAR formats, and extra features introduced into the T cells; and (4) patient pretreatments, injection sites, and safety measurements. Finally, the few data on clinical outcome are reported. The last assessment of clinicaltrials.gov for the data summarized in this paper was on 4 August 2020.

Combinatorial Nanomedicine Made of Squalenoyl-Gemcitabine and Edelfosine for the Treatment of Osteosarcoma

Due to chemoresistance and a high propensity to form lung metastasis, survival rates in pediatric osteosarcoma (OS) are poor. With the aim to improve anticancer activity in pediatric OS, a multidrug nanomedicine was designed using the alkyl-lysophospholipid edelfosine (EF) co-assembled with squalenoyl–gemcitabine (SQ–Gem) to form nanoassemblies (NAs) of 50 nm. SQ–Gem/EF NAs modified the total Gem pool exposure in the blood stream in comparison with SQ–Gem NAs, which correlated with a better tolerability and a lower toxicity profile after multiple intravenous administrations in mice. For in vivo preclinical assessment in an orthotopic OS tumor model, P1.15 OS cells were intratibially injected in athymic nude mice. SQ–Gem/EF NAs considerably decreased the primary tumor growth kinetics and reduced the number of lung metastases. Our findings support the candidature of this anticancer nanomedicine as a potential pediatric OS therapy.

Small Nucleolar RNAs Determine Resistance to Doxorubicin in Human Osteosarcoma

Doxorubicin (Dox) is one of the most important first-line drugs used in osteosarcoma therapy. Multiple and not fully clarified mechanisms, however, determine resistance to Dox. With the aim of identifying new markers associated with Dox-resistance, we found a global up-regulation of small nucleolar RNAs (snoRNAs) in human Dox-resistant osteosarcoma cells. We investigated if and how snoRNAs are linked to resistance. After RT-PCR validation of snoRNAs up-regulated in osteosarcoma cells with different degrees of resistance to Dox, we overexpressed them in Dox-sensitive cells. We then evaluated Dox cytotoxicity and changes in genes relevant for osteosarcoma pathogenesis by PCR arrays. SNORD3A, SNORA13 and SNORA28 reduced Dox-cytotoxicity when over-expressed in Dox-sensitive cells. In these cells, GADD45A and MYC were up-regulated, TOP2A was down-regulated. The same profile was detected in cells with acquired resistance to Dox. GADD45A/MYC-silencing and TOP2A-over-expression counteracted the resistance to Dox induced by snoRNAs. We reported for the first time that snoRNAs induce resistance to Dox in human osteosarcoma, by modulating the expression of genes involved in DNA damaging sensing, DNA repair, ribosome biogenesis, and proliferation. Targeting snoRNAs or down-stream genes may open new treatment perspectives in chemoresistant osteosarcomas.

Genomics and Therapeutic Vulnerabilities of Primary Bone Tumors

Osteosarcoma, Ewing sarcoma and chondrosarcoma are rare diseases but the most common primary tumors of bone. The genes directly involved in the sarcomagenesis, tumor progression and treatment responsiveness are not completely defined for these tumors, and the powerful discovery of genetic analysis is highly warranted in the view of improving the therapy and cure of patients. The review summarizes recent advances concerning the molecular and genetic background of these three neoplasms and, of their most common variants, highlights the putative therapeutic targets and the clinical trials that are presently active, and notes the fundamental issues that remain unanswered. In the era of personalized medicine, the rarity of sarcomas may not be the major obstacle, provided that each patient is studied extensively according to a road map that combines emerging genomic and functional approaches toward the selection of novel therapeutic strategies.

ABCA1/ABCB1 Ratio Determines Chemo- and Immune-Sensitivity in Human Osteosarcoma

The ATP Binding Cassette transporter B1 (ABCB1) induces chemoresistance in osteosarcoma, because it effluxes doxorubicin, reducing the intracellular accumulation, toxicity, and immunogenic cell death induced by the drug. The ATP Binding Cassette transporter A1 (ABCA1) effluxes isopentenyl pyrophosphate (IPP), a strong activator of anti-tumor Vγ9Vδ2 T-cells. Recruiting this population may represent an alternative strategy to rescue doxorubicin efficacy in ABCB1-expressing osteosarcoma. In this work, we analyzed how ABCA1 and ABCB1 are regulated in osteosarcoma, and if increasing the ABCA1-dependent activation of Vγ9Vδ2 T-cells could be an effective strategy against ABCB1-expressing osteosarcoma. We used 2D-cultured doxorubicin-sensitive human U-2OS and Saos-2 cells, their doxorubicin-resistant sublines (U-2OS/DX580 and Saos-2/DX580), and 3D cultures of U-2OS and Saos-2 cells. DX580-sublines and 3D cultures had higher levels of ABCB1 and higher resistance to doxorubicin than parental cells. Surprisingly, they had reduced ABCA1 levels, IPP efflux, and Vγ9Vδ2 T-cell-induced killing. In these chemo-immune-resistant cells, the Ras/Akt/mTOR axis inhibits the ABCA1-transcription induced by Liver X Receptor α (LXRα); Ras/ERK1/2/HIF-1α axis up-regulates ABCB1. Targeting the farnesylation of Ras with self-assembling nanoparticles encapsulating zoledronic acid (NZ) simultaneously inhibited both axes. In humanized mice, NZ reduced the growth of chemo-immune-resistant osteosarcomas, increased intratumor necro-apoptosis, and ABCA1/ABCB1 ratio and Vγ9Vδ2 T-cell infiltration. We suggest that the ABCB1^highABCA1^low phenotype is indicative of chemo-immune-resistance. We propose aminobisphosphonates as new chemo-immune-sensitizing tools against drug-resistant osteosarcomas.