Osteosarcoma-initiating cells show high aerobic glycolysis and attenuation of oxidative phosphorylation mediated by LIN28B

LIN28B induced PCAT5 promotes endometrial cancer progression and glycolysis via IGF2BP3 deubiquitination

Endometrial cancer (EC) cells exhibit abnormal glucose metabolism, characterized by increased aerobic glycolysis and decreased oxidative phosphorylation. Targeting cellular glucose metabolism in these cells could be an effective therapeutic approach for EC. This study aimed to assess the roles of LIN28B, PCAT5, and IGF2BP3 in the glucose metabolism, proliferation, migration, and invasion of EC cells. LIN28B highly expressed in EC, binds and stabilizes PCAT5. PCAT5, overexpressed in EC, and its 1485-2288nt region can bind to the KH1-2 domain of IGF2BP3 to prevent MKRN2 from binding to the K294 ubiquitination site of IGF2BP3, thus stabilizing IGF2BP3. Finally, IGF2BP3 promotes the aerobic glycolysis, proliferation, migration and invasion of EC cells by stabilizing the key enzymes of glucose metabolism HK2 and PKM2. Taken together, our data reveal that the LIN28B/PCAT5/IGF2BP3 axis is critical for glucose reprogramming and malignant biological behavior in EC cells. Therefore, targeting this axis may contribute to the development of a novel therapeutic strategy for EC metabolism.

The OSR9 Regimen: A New Augmentation Strategy for Osteosarcoma Treatment Using Nine Older Drugs from General Medicine to Inhibit Growth Drive

As things stand in 2023, metastatic osteosarcoma commonly results in death. There has been little treatment progress in recent decades. To redress the poor prognosis of metastatic osteosarcoma, the present regimen, OSR9, uses nine already marketed drugs as adjuncts to current treatments. The nine drugs in OSR9 are: (1) the antinausea drug aprepitant, (2) the analgesic drug celecoxib, (3) the anti-malaria drug chloroquine, (4) the antibiotic dapsone, (5) the alcoholism treatment drug disulfiram, (6) the antifungal drug itraconazole, (7) the diabetes treatment drug linagliptin, (8) the hypertension drug propranolol, and (9) the psychiatric drug quetiapine. Although none are traditionally used to treat cancer, all nine have attributes that have been shown to inhibit growth-promoting physiological systems active in osteosarcoma. In their general medicinal uses, all nine drugs in OSR9 have low side-effect risks. The current paper reviews the collected data supporting the role of OSR9.

Regulation and signaling pathways in cancer stem cells: implications for targeted therapy for cancer

Cancer stem cells (CSCs), initially identified in leukemia in 1994, constitute a distinct subset of tumor cells characterized by surface markers such as CD133, CD44, and ALDH. Their behavior is regulated through a complex interplay of networks, including transcriptional, post-transcriptional, epigenetic, tumor microenvironment (TME), and epithelial-mesenchymal transition (EMT) factors. Numerous signaling pathways were found to be involved in the regulatory network of CSCs. The maintenance of CSC characteristics plays a pivotal role in driving CSC-associated tumor metastasis and conferring resistance to therapy. Consequently, CSCs have emerged as promising targets in cancer treatment. To date, researchers have developed several anticancer agents tailored to specifically target CSCs, with some of these treatment strategies currently undergoing preclinical or clinical trials. In this review, we outline the origin and biological characteristics of CSCs, explore the regulatory networks governing CSCs, discuss the signaling pathways implicated in these networks, and investigate the influential factors contributing to therapy resistance in CSCs. Finally, we offer insights into preclinical and clinical agents designed to eliminate CSCs.

C1632 inhibits ovarian cancer cell growth and migration by inhibiting LIN28 B/let-7/FAK signaling pathway and FAK phosphorylation

The highly conserved RNA-binding protein LIN28B and focal adhesion kinase (FAK) are significantly upregulated in ovarian cancer (OC), serving as markers for disease progression and prognosis. Nonetheless, the correlation between LIN28B and FAK, as well as the pharmacological effects of the LIN28 inhibitor C1632, in OC cells have not been elucidated. The present study demonstrates that C1632 significantly reduced the rate of DNA replication, arrested the cell cycle at the G0/G1 phase, consequently reducing cell viability, and impeding clone formation. Moreover, treatment with C1632 decreased cell-matrix adhesion, as well as inhibited cell migration and invasion. Further mechanistic studies revealed that C1632 inhibited the OC cell proliferation and migration by concurrently inhibiting LIN28 B/let-7/FAK signaling pathway and FAK phosphorylation. Furthermore, C1632 exhibited an obvious inhibitory effect on OC cell xenograft tumors in mice. Altogether, these findings identified that LIN28 B/let-7/FAK is a valuable target in OC and C1632 is a promising onco-therapeutic agent for OC treatment.

Cancer/Testis Antigens as Targets for RNA-Based Anticancer Therapy

In the last few decades, RNA-based drugs have emerged as a promising candidate in the treatment of various diseases. The introduction of messenger RNA (mRNA) as a vaccine or therapeutic agent enables the production of almost any functional protein/peptide. The key to applying RNA therapy in clinical trials is developing safe and effective delivery systems. Exosomes and lipid nanoparticles (LNPs) have been exploited as promising vehicles for drug delivery. This review discusses the feasibility of exosomes and LNPs as vehicles for mRNA delivery. Cancer/testis antigens (CTAs) show restricted expression in normal tissues and widespread expression in cancer tissues. Many of these CTAs show expression in the sera of patients with cancers. These characteristics of CTAs make them excellent targets for cancer immunotherapy. This review summarizes the roles of CTAs in various life processes and current studies on mRNAs encoding CTAs. Clinical studies present the beneficial effects of mRNAs encoding CTAs in patients with cancers. This review highlight clinical studies employing mRNA-LNPs encoding CTAs.

Construction and validation of a novel cuproptosis-mitochondrion prognostic model related with tumor immunity in osteosarcoma

BACKGROUND

The purpose of this study was to develop a new prognostic model for osteosarcoma based on cuproptosis-mitochondrion genes.

MATERIALS AND METHODS

The data of osteosarcoma were obtained from TARGET database. By using Cox regression and LASSO regression analysis, a novel risk score was constructed based on cuproptosis-mitochondrion genes. Kaplan-Meier, ROC curve and independent prognostic analyses were performed to validate the risk score in GSE21257 dataset. Then, a predictive nomogram was constructed and further validated by calibration plot, C-index and ROC curve. Based on the risk score, all patients were divided into high-risk and low-risk group. GO and KEGG enrichment, immune correlation and drug sensitivity analyses were performed between groups. Real-time quantitative PCR verified the expression of cuproptosis-mitochondrion prognostic model genes in osteosarcoma. And we explored the function of FDX1 in osteosarcoma by western blotting, CCK8, colony formation assay, wound healing assay and transwell assays.

RESULTS

A total of six cuproptosis-mitochondrion genes (FDX1, COX11, MFN2, TOMM20, NDUFB9 and ATP6V1E1) were identified. A novel risk score and associated prognostic nomogram were constructed with high clinical application value. Strong differences in function enrichment and tumor immune microenvironment were shown between groups. Besides, the correlation of cuproptosis-mitochondrion genes and drug sensitivity were revealed to search for potential therapeutic target. The expression of FDX1, COX11, MFN2, TOMM20 and NDUFB9 at mRNA level was elevated in osteosarcoma cells compared with normal osteoblast hFOB1.19. The mRNA expression level of ATP6V1E1 was decreased in osteosarcoma. Compared with hFOB1.19, western blotting revealed that the expression of FDX1 was significantly elevated in osteosarcoma cells. Functional experiments indicated that FDX1 mainly promoted the migration of osteosarcoma rather than proliferation.

CONCLUSIONS

We developed a novel prognostic model of osteosarcoma based on cuproptosis-mitochondrion genes, which provided great guidance in survival prediction and individualized treatment decision making for patients with osteosarcoma.

Current status of porous coordination networks (PCNs) derived porphyrin spacers for cancer therapy

INTRODUCTION

Porous coordination networks (PCNs) have been widely used in large number of applications such as light harvesting, catalysis, and biomedical applications. Inserting porphyrins into PCNs scaffolds can alleviate the solubility and chemical stability problems associated with porphyrin ligands and add functionality to PCNs. The discovery that some PCNs materials have photosensitizer and acoustic sensitizer properties has attracted significant attention in the field of biomedicine, particularly in cancer therapy. This article describes the latest applications of the porphyrin ligand-based family of PCNs in cancer chemodynamic therapy (CDT), photodynamic therapy (PDT), sonodynamic therapy (SDT), photothermal therapy (PTT), and combination therapies and offers some observations and reflections on them.

AREAS COVERED

This article discusses the use of the PCN family of MOFs in cancer treatment, specifically focusing on chemodynamic therapy, sonodynamic therapy, photodynamic therapy, photothermal therapy, and combination therapy.

EXPERT OPINION

Although a large number of PCNs have been developed for use in novel cancer therapeutic approaches, further improvements are needed to advance the use of PCNs in the clinic. For example, the main mechanism of action of PCNs against cancer and the metabolic processes in organisms, and how to construct PCNs that maintain good stability in the complex environment of organisms.

The role of LIN28B in tumor progression and metastasis in solid tumor entities

LIN28B is an RNA-binding protein that targets a broad range of microRNAs and modulates their maturation and activity. Under normal conditions, LIN28B is exclusively expressed in embryogenic stem cells, blocking differentiation and promoting proliferation. In addition, it can play a role in epithelial-to-mesenchymal transition by repressing the biogenesis of let-7 microRNAs. In malignancies, LIN28B is frequently overexpressed, which is associated with increased tumor aggressiveness and metastatic properties. In this review, we discuss the molecular mechanisms of LIN28B in promoting tumor progression and metastasis in solid tumor entities and its potential use as a clinical therapeutic target and biomarker.

High GNG4 predicts adverse prognosis for osteosarcoma: Bioinformatics prediction and experimental verification

Background

Guanine nucleotide binding (G) protein subunit γ 4 (GNG4) is closely related to the malignant progression and poor prognosis of various tumours. However, its role and mechanism in osteosarcoma remain unclear. This study aimed to elucidate the biological role and prognostic value of GNG4 in osteosarcoma.

Methods

Osteosarcoma samples in the GSE12865, GSE14359, GSE162454 and TARGET datasets were selected as the test cohorts. The expression level of GNG4 between normal and osteosarcoma was identified in GSE12865 and GSE14359. Based on the osteosarcoma single-cell RNA sequencing (scRNA-seq) dataset GSE162454, differential expression of GNG4 among cell subsets was identified at the single-cell level. As the external validation cohort, 58 osteosarcoma specimens from the First Affiliated Hospital of Guangxi Medical University were collected. Patients with osteosarcoma were divided into high- and low-GNG4 groups. The biological function of GNG4 was annotated using Gene Ontology, gene set enrichment analysis, gene expression correlation analysis and immune infiltration analysis. Kaplan-Meier survival analysis was conducted and receiver operating characteristic (ROC) curves were calculated to determine the reliability of GNG4 in predicting prognostic significance and diagnostic value. Functional in vitro experiments were performed to explore the function of GNG4 in osteosarcoma cells.

Results

GNG4 was generally highly expressed in osteosarcoma. As an independent risk factor, high GNG4 was negatively correlated with both overall survival and event-free survival. Furthermore, GNG4 was a good diagnostic marker for osteosarcoma, with an area under the receiver operating characteristic curve (AUC) of more than 0.9. Functional analysis suggested that GNG4 may promote the occurrence of osteosarcoma by regulating ossification, B-cell activation, the cell cycle and the proportion of memory B cells. In in vitro experiments, silencing of GNG4 inhibited the viability, proliferation and invasion of osteosarcoma cells.

Conclusion

Through bioinformatics analysis and experimental verification, high expression of GNG4 in osteosarcoma was identified as an oncogene and reliable biomarker for poor prognosis. This study helps to elucidate the significant potential of GNG4 in carcinogenesis and molecular targeted therapy for osteosarcoma.

A novel molecular classification method for osteosarcoma based on tumor cell differentiation trajectories

Subclassification of tumors based on molecular features may facilitate therapeutic choice and increase the response rate of cancer patients. However, the highly complex cell origin involved in osteosarcoma (OS) limits the utility of traditional bulk RNA sequencing for OS subclassification. Single-cell RNA sequencing (scRNA-seq) holds great promise for identifying cell heterogeneity. However, this technique has rarely been used in the study of tumor subclassification. By analyzing scRNA-seq data for six conventional OS and nine cancellous bone (CB) samples, we identified 29 clusters in OS and CB samples and discovered three differentiation trajectories from the cancer stem cell (CSC)-like subset, which allowed us to classify OS samples into three groups. The classification model was further examined using the TARGET dataset. Each subgroup of OS had different prognoses and possible drug sensitivities, and OS cells in the three differentiation branches showed distinct interactions with other clusters in the OS microenvironment. In addition, we verified the classification model through IHC staining in 138 OS samples, revealing a worse prognosis for Group B patients. Furthermore, we describe the novel transcriptional program of CSCs and highlight the activation of EZH2 in CSCs of OS. These findings provide a novel subclassification method based on scRNA-seq and shed new light on the molecular features of CSCs in OS and may serve as valuable references for precision treatment for and therapeutic development in OS.

In vitro effects of ascorbic acid on viability and metabolism of patients' osteosarcoma stem cells

Stagnation in novelties of osteosarcoma (OS) treatment indicates the need for new therapeutic methods. OS cancer stem cells (OS-CSC) are taught to have the ability to self-renew and develop mechanisms of anticancer drug resistance, and this is why it is difficult to eradicate them. Their metabolism has been recognized as a potential target of therapeutic action. Ascorbic acid (AA) is considered to act pro-oxidative against OS-CSC in vitro by oxidative effect and by inhibition of glycolysis. This study examined an in vitro impact of AA on OS-CSC metabolism isolated from patients' biopsies, with the aim of better understanding of OS-CSC metabolism and the action of AA on OS-CSC. OS-CSC were isolated using a sphere culture system and identified as stem cells using Hoechst 33342 exclusion assay. Determination of the dominant type of metabolism of OS-CSC, parental OS cells, human mesenchymal stem cells (hMSC) and U2OS OS lineage before and after AA treatment was done by Seahorse XF (Agilent). Cytotoxicity of high-dose AA was confirmed by the MTT test and was proven for all the examined cell types as well as HEK293. Seahorse technology showed that OS-CSC can potentially use both glycolysis and oxidative phosphorylation (OXPHOS), and can turn to glycolysis and slow metabolic potential in unfavorable conditions such as incubation in AA.

A novel risk score model based on glycolysis-related genes and a prognostic model for predicting overall survival of osteosarcoma patients

This study aims to construct a novel risk score model based on glycolysis-related genes in osteosarcoma and to build and validate a prognostic model for predicting overall survival of patients with osteosarcoma. The transcriptome data and corresponding clinical data of patients with osteosarcoma were obtained from The Cancer Genome Atlas (TCGA) as the training set, and from Gene Expression Omnibus (GEO) database as the validation set. Univariate Cox regression analysis was used to screen the prognostic glycolysis-related genes. The risk coefficient of each glycolysis-related gene was calculated using LASSO regression analysis. Using the median risk score as the cut-off point, patients were divided into high-risk and low-risk groups. Kaplan-Meier survival analysis was used to determine whether there was a significant difference in the overall survival between the two groups. The nomogram was constructed according to the results of multivariate Cox regression. The C-index was calculated, the calibration chart, clinical decision curve and receiver operating characteristic curve were drawn to evaluate the predictive performance of the nomogram. We performed Gene Ontology and Kyoto encyclopedia of genes and genomics enrichment analysis to explore the potential mechanism of prognostic-related glycolysis genes in osteosarcoma. A total of 88 and 53 cases were obtained from the TCGA and GEO database, respectively. A total of 10 key glycolytic genes related to prognosis were screened out. The Kaplan-Meier survival curve revealed that the overall survival of the high-risk group was significantly shorter than that of the low-risk group. The C indices of the training set and the verification set were 0.882 and 0.828, respectively. Our findings will provide further understanding of clinical prognostic outcomes of osteosarcoma patients.

Detection and surveillance of circulating tumor cells in osteosarcoma for predicting therapy response and prognosis

Objective:

Osteosarcoma (OS) is an aggressive, highly metastatic, relatively drug-resistant bone tumor with poor long-term survival rates. The presence and persistence of circulating tumor cells (CTCs) in the peripheral blood are believed to be associated with treatment inefficiency and distant metastases. A blood-based CTC test is thus greatly needed for monitoring disease progression and predicting clinical outcomes. However, traditional methods cannot detect CTCs from tumors of mesenchymal origin such as OS, and research on CTC detection in mesenchymal tumors has been hindered for years.

Methods:

In this study, we developed a CTC test based on hexokinase 2, a metabolic function-associated marker, for the detection and surveillance of OS CTCs, and subsequently explored its clinical value. Twelve patients with OS were enrolled as the training cohort for serial CTC tests. Dynamic CTC counting, in combination with therapy evaluation and post-treatment follow-up, was used to establish a model for predicting post-chemotherapy evaluation and disease-free survival, and the model was further validated with a cohort of 8 patients with OS.

Results:

Two dynamic CTC number patterns were identified, and the resulting predictive model exhibited 92% consistency with the clinical outcomes. This model suggested that a single CTC test has similar predictive power to serial CTC analysis. In the validation cohort, the single CTC test exhibited 100% and 87.5% consistency with therapy response and disease-free survival, respectively.

Conclusions:

Our non-invasive test for detection and surveillance of CTCs enables accurate prediction of therapy efficiency and prognosis, and may be clinically valuable for avoiding inefficient therapy and prolonging survival.

Expression of lactate-related signatures correlates with immunosuppressive microenvironment and prognostic prediction in ewing sarcoma

Objectives: Ewing sarcoma (EWS) is an aggressive tumor of bone and soft tissue. Growing evidence indicated lactate as a pivotal mediator of crosstalk between tumor energy metabolism and microenvironmental regulation. However, the contribution of lactate-related genes (LRGs) in EWS is still unclear.

Methods: We obtained the transcriptional data of EWS patients from the GEO database and identified differentially expressed-LRGs (DE-LRGs) between EWS patient samples and normal tissues. Unsupervised cluster analysis was utilized to recognize lactate modulation patterns based on the expression profile of DE-LRGs. Functional enrichment including GSEA and GSVA analysis was conducted to identify molecular signaling enriched in different subtypes. ESTIMATE, MCP and CIBERSORT algorithm was used to explore tumor immune microenvironment (TIME) between subtypes with different lactate modulation patterns. Then, lactate prognostic risk signature was built via univariate, LASSO and multivariate Cox analysis. Finally, we performed qPCR analysis to validate candidate gene expression.

Result: A total of 35 DE-LRGs were identified and functional enrichment analysis indicated that these LRGs were involved in mitochondrial function. Unsupervised cluster analysis divided EWS patients into two lactate modulation patterns and we revealed that patients with Cluster 1 pattern were linked to poor prognosis and high lactate secretion status. Moreover, TIME analysis indicated that the abundance of multiple immune infiltrating cells were dramatically elevated in Cluster 1 to Cluster 2, including CAFs, endothelial cells, Macrophages M2, etc., which might contribute to immunosuppressive microenvironment. We also noticed that expression of several immune checkpoint proteins were clearly increased in Cluster 1 to Cluster 2. Subsequently, seven genes were screened to construct LRGs prognostic signature and the performance of the resulting signature was validated in the validation cohort. Furthermore, a nomogram integrating LRGs signature and clinical characteristics was developed to predict effectively the 4, 6, and 8-year prognosis of EWS patients.

Conclusion: Our study revealed the role of LRGs in immunosuppressive microenvironment and predicting prognosis in EWS and provided a robust tool to predict the prognosis of EWS patients.

In Situ Analysis of mTORC1/C2 and Metabolism-Related Proteins in Pediatric Osteosarcoma

Activation of the mTOR pathway has been observed in osteosarcoma, however the inhibition of mammalian target of rapamycin (mTOR) complex 1 has had limited results in osteosarcoma treatment. Certain metabolic pathways can be altered by mTOR activation, which can affect survival. Our aim was to characterize the mTOR profile and certain metabolic alterations in pediatric osteosarcoma to determine the interactions between the mTOR pathway and metabolic pathways. We performed immunohistochemistry on 28 samples to analyze the expression of mTOR complexes such as phospho-mTOR (pmTOR), phosphorylated ribosomal S6 (pS6), and rapamycin-insensitive companion of mTOR (rictor). To characterize metabolic pathway markers, we investigated the expression of phosphofructokinase (PFK), lactate dehydrogenase-A (LDHA), β-F1-ATPase (ATPB), glucose-6-phosphate dehydrogenase (G6PDH), glutaminase (GLS), fatty acid synthetase (FASN), and carnitin-O-palmitoyltransferase-1 (CPT1A). In total, 61% of the cases showed low mTOR activity, but higher pmTOR expression was associated with poor histological response to chemotherapy and osteoblastic subtype. Rictor expression was higher in metastatic disease and older age at the time of diagnosis. Our findings suggest the importance of the Warburg-effect, pentose-phosphate pathway, glutamine demand, and fatty-acid beta oxidation in osteosarcoma cells. mTOR activation is linked to several metabolic pathways. We suggest performing a detailed investigation of the mTOR profile before considering mTORC1 inhibitor therapy. Our findings highlight that targeting certain metabolic pathways could be an alternative therapeutic approach.

Cancer Stem Cells: Metabolic Characterization for Targeted Cancer Therapy

The subpopulation of cancer stem cells (CSCs) within tumor bulk are known for tumor recurrence and metastasis. CSCs show intrinsic resistance to conventional therapies and phenotypic plasticity within the tumor, which make these a difficult target for conventional therapies. CSCs have different metabolic phenotypes based on their needs as compared to the bulk cancer cells. CSCs show metabolic plasticity and constantly alter their metabolic state between glycolysis and oxidative metabolism (OXPHOS) to adapt to scarcity of nutrients and therapeutic stress. The metabolic characteristics of CSCs are distinct compared to non-CSCs and thus provide an opportunity to devise more effective strategies to target CSCs. Mechanism for metabolic switch in CSCs is still unravelled, however existing evidence suggests that tumor microenvironment affects the metabolic phenotype of cancer cells. Understanding CSCs metabolism may help in discovering new and effective clinical targets to prevent cancer relapse and metastasis. This review summarises the current knowledge of CSCs metabolism and highlights the potential targeted treatment strategies.

Avenues of research in dietary interventions to target tumor metabolism in osteosarcoma

Osteosarcoma (OS) is the most frequent primary bone cancer, affecting mostly children and adolescents. Although much progress has been made throughout the years towards treating primary OS, the 5-year survival rate for metastatic OS has remained at only 20% for the last 30 years. Therefore, more efficient treatments are needed. Recent studies have shown that tumor metabolism displays a unique behavior, and plays important roles in tumor growth and metastasis, making it an attractive potential target for novel therapies. While normal cells typically fuel the oxidative phosphorylation (OXPHOS) pathway with the products of glycolysis, cancer cells acquire a plastic metabolism, uncoupling these two pathways. This allows them to obtain building blocks for proliferation from glycolytic intermediates and ATP from OXPHOS. One way to target the metabolism of cancer cells is through dietary interventions. However, while some diets have shown anticancer effects against certain tumor types in preclinical studies, as of yet none have been tested to treat OS. Here we review the features of tumor metabolism, in general and about OS, and propose avenues of research in dietary intervention, discussing strategies that could potentially be effective to target OS metabolism.

Cancer/testis antigens: from serology to mRNA cancer vaccine

Cancer/testis antigens (CTAs) are a group of tumor antigens expressed in numerous cancer tissues, as well as in the testis and placental tissues. There are over 200 CTAs supported by serology and expression data. The expression patterns of CTAs reflect the similarities between the processes of gametogenesis and tumorigenesis. It is notable that CTAs are highly expressed in three types of cancers (lung cancer, bladder cancer, and skin cancer), all of which have a metal etiology. Here, we review the expression, regulation, and function of CTAs and their translational prospects as cancer biomarkers and treatment targets. Many CTAs are highly immunogenic, tissue-specific, and frequently expressed in cancer tissues but not under physiological conditions, rendering them promising candidates for cancer detection. Some CTAs are associated with clinical outcomes, so they may serve as prognostic biomarkers. A small number of CTAs are membrane-bound, making them ideal targets for chimeric antigen receptor (CAR) T cells. Mounting evidence suggests that CTAs induce humoral or cellular immune responses, providing cancer immunotherapeutic opportunities for T-cell receptors (TCRs), CAR T cell, antibody-based therapy and peptide- or mRNA-based vaccines. Indeed, CTAs are the dominating non-mutated targets in mRNA cancer vaccine development. Clinical trials on CTA TCR and vaccines have shown effectiveness, safety, and tolerance, but these successes are limited to a small number of patients. In-depth studies on CTA expression and function are needed to improve CTA-based immunotherapy.

Metabolic Targeting of Cancer Stem Cells

Most human tumors possess a high heterogeneity resulting from both clonal evolution and cell differentiation program. The process of cell differentiation is initiated from a population of cancer stem cells (CSCs), which are enriched in tumor-regenerating and tumor-propagating activities and responsible for tumor maintenance and regrowth after treatment. Intrinsic resistance to conventional therapies, as well as a high degree of phenotypic plasticity, makes CSCs hard-to-target tumor cell population. Reprogramming of CSC metabolic pathways plays an essential role in tumor progression and metastatic spread. Many of these pathways confer cell adaptation to the microenvironmental stresses, including a shortage of nutrients and anti-cancer therapies. A better understanding of CSC metabolic dependences as well as metabolic communication between CSCs and the tumor microenvironment are of utmost importance for efficient cancer treatment. In this mini-review, we discuss the general characteristics of CSC metabolism and potential metabolic targeting of CSC populations as a potent strategy to enhance the efficacy of conventional treatment approaches.

Spatiotemporal metabolic dynamics of the photosensitizer talaporfin sodium in carcinoma and sarcoma

Photodynamic therapy (PDT) using the photosensitizer talaporfin sodium (talaporfin) is a new mode of treatment for cancer. However, the metabolic mechanism of talaporfin has not been clarified. Thus, we investigated the uptake, transportation, and elimination mechanisms of talaporfin in carcinoma and sarcoma. The results showed that talaporfin co‐localized in early endosomes and lysosomes. Talaporfin uptake was via clathrin‐ and caveolae‐dependent endocytosis and a high amount of intracellular ATP was essential. Inhibition of lysosomal enzymes maintained intracellular talaporfin levels. Inhibition of K‐Ras signaling reduced talaporfin uptake in carcinoma and sarcoma cell lines. Talaporfin was taken up by clathrin‐ and caveolae‐dependent endocytosis, translocated from early endosomes to lysosomes, and finally degraded by lysosomes. We also demonstrated that ATP is essential for the uptake of talaporfin and that activation of K‐Ras is involved as a regulatory mechanism. These results provide new insights into the metabolism of talaporfin in cancer cells for the enhancement of PDT for carcinoma and sarcoma.

Development of an artificial antibody specific for HLA/peptide complex derived from cancer stem-like cell/cancer-initiating cell antigen DNAJB8

Background

Peptide-vaccination therapy targeting tumour-associated antigens can elicit immune responses, but cannot be used to eliminate large tumour burden. In this study, we developed a therapeutic single-chain variable-fragment (scFv) antibody that recognises the cancer stem-like cell/cancer-initiating cell (CSC/CIC) antigen, DNAJB8.

Methods

We screened scFv clones reacting with HLA-A24:20/DNAJB8-derived peptide (DNAJB8_143) complex using naive scFv phage-display libraries. Reactivity and affinity of scFv clones against the cognate antigen were quantified using FACS and surface plasmon resonance. Candidate scFv clones were engineered to human IgG1 (hIgG1) and T-cell-engaging bispecific antibody (CD3xJB8). Complement-dependent cytotoxicity (CDC) and bispecific antibody-dependent cellular cytotoxicity (BADCC) were assessed.

Results

scFv clones A10 and B10 were isolated after bio-panning. Both A10-hIgG1 and B10-hIgG1 reacted with DNAJB8-143 peptide-pulsed antigen-presenting cells and HLA-A24(+)/DNAJB8(+) renal cell carcinoma and osteosarcoma cell lines. A10-hIgG1 and B10-hIgG1 showed strong affinity with the cognate HLA/peptide complex (K_D = 2.96 × 10⁻⁹ M and 5.04 × 10⁻⁹ M, respectively). A10-hIgG1 and B10-hIgG1 showed CDC against HLA-A24(+)/DNAJB8(+) cell lines. B10-(CD3xJB8) showed superior BADCC to A10-(CD3xJB8).

Conclusion

We isolated artificial scFv antibodies reactive to CSC/CIC antigen DNAJB8-derived peptide naturally present on renal cell carcinoma and sarcoma. Immunotherapy using these engineered antibodies could be promising.

Cancer Stem Cells in Soft-Tissue Sarcomas

Soft tissue sarcomas (STS) are a rare group of mesenchymal solid tumors with heterogeneous genetic profiles and clinical features. Systemic chemotherapy is the backbone treatment for advanced STS; however, STS frequently acquire resistance to standard therapies, which highlights the need to improve treatments and identify novel therapeutic targets. Increases in the knowledge of the molecular pathways that drive sarcomas have brought to light different molecular alterations that cause tumor initiation and progression. These findings have triggered a breakthrough of targeted therapies that are being assessed in clinical trials. Cancer stem cells (CSCs) exhibit mesenchymal stem cell (MSC) features and represent a subpopulation of tumor cells that play an important role in tumor progression, chemotherapy resistance, recurrence and metastasis. In fact, CSCs phenotypes have been identified in sarcomas, allied to drug resistance and tumorigenesis. Herein, we will review the published evidence of CSCs in STS, discussing the molecular characteristic of CSCs, the commonly used isolation techniques and the new possibilities of targeting CSCs as a way to improve STS treatment and consequently patient outcome.

Targeting Nuclear NAD+ Synthesis Inhibits DNA Repair, Impairs Metabolic Adaptation and Increases Chemosensitivity of U-2OS Osteosarcoma Cells

Osteosarcoma (OS) is the most common bone tumor in children and adolescents. Modern OS treatment, based on the combination of neoadjuvant chemotherapy (cisplatin + doxorubicin + methotrexate) with subsequent surgical removal of the primary tumor and metastases, has dramatically improved overall survival of OS patients. However, further research is needed to identify new therapeutic targets. Here we report that expression level of the nuclear NAD synthesis enzyme, nicotinamide mononucleotide adenylyltransferase-1 (NMNAT1), increases in U-2OS cells upon exposure to DNA damaging agents, suggesting the involvement of the enzyme in the DNA damage response. Moreover, genetic inactivation of NMNAT1 sensitizes U-2OS osteosarcoma cells to cisplatin, doxorubicin, or a combination of these two treatments. Increased cisplatin-induced cell death of NMNAT1^−/− cells showed features of both apoptosis and necroptosis, as indicated by the protective effect of the caspase-3 inhibitor z-DEVD-FMK and the necroptosis inhibitor necrostatin-1. Activation of the DNA damage sensor enzyme poly(ADP-ribose) polymerase 1 (PARP1), a major consumer of NAD⁺ in the nucleus, was fully blocked by NMNAT1 inactivation, leading to increased DNA damage (phospho-H2AX foci). The PARP inhibitor, olaparib, sensitized wild type but not NMNAT1^−/− cells to cisplatin-induced anti-clonogenic effects, suggesting that impaired PARP1 activity is important for chemosensitization. Cisplatin-induced cell death of NMNAT1^−/− cells was also characterized by a marked drop in cellular ATP levels and impaired mitochondrial respiratory reserve capacity, highlighting the central role of compromised cellular bioenergetics in chemosensitization by NMNAT1 inactivation. Moreover, NMNAT1 cells also displayed markedly higher sensitivity to cisplatin when grown as spheroids in 3D culture. In summary, our work provides the first evidence that NMNAT1 is a promising therapeutic target for osteosarcoma and possibly other tumors as well.

Lactate in Sarcoma Microenvironment: Much More than just a Waste Product

Sarcomas are rare and heterogeneous malignant tumors relatively resistant to radio- and chemotherapy. Sarcoma progression is deeply dependent on environmental conditions that sustain both cancer growth and invasive abilities. Sarcoma microenvironment is composed of different stromal cell types and extracellular proteins. In this context, cancer cells may cooperate or compete with stromal cells for metabolic nutrients to sustain their survival and to adapt to environmental changes. The strict interplay between stromal and sarcoma cells deeply affects the extracellular metabolic milieu, thus altering the behavior of both cancer cells and other non-tumor cells, including immune cells. Cancer cells are typically dependent on glucose fermentation for growth and lactate is one of the most heavily increased metabolites in the tumor bulk. Currently, lactate is no longer considered a waste product of the Warburg metabolism, but novel signaling molecules able to regulate the behavior of tumor cells, tumor-stroma interactions and the immune response. In this review, we illustrate the role of lactate in the strong acidity microenvironment of sarcoma. Really, in the biological context of sarcoma, where novel targeted therapies are needed to improve patient outcomes in combination with current therapies or as an alternative treatment, lactate targeting could be a promising approach to future clinical trials.

Osteosarcoma-initiating cells show high aerobic glycolysis and attenuation of oxidative phosphorylation mediated by LIN28B

Osteosarcoma (OS) is a highly malignant bone tumor and the prognosis for non‐responders to chemotherapy remains poor. Previous studies have shown that human sarcomas contain sarcoma‐initiating cells (SIC), which have the characteristics of high tumorigenesis and resistance to chemotherapy. In the present study, we characterized SIC of a novel OS cell line, screened for SIC‐related genes, and tried to regulate the proliferation of OS by metabolic interference. Initially, we established a new human OS cell line (OS13) and isolated clones showing higher tumorigenesis as SIC (OS^HIGH) and counterpart clones. OS^HIGH cells showed chemoresistance and their metabolism highly depended on aerobic glycolysis and suppressed oxidative phosphorylation. Using RNA‐sequencing, we identified LIN28B as a SIC‐related gene highly expressed in OS^HIGH cells. mRNA of LIN28B was expressed in sarcoma cell lines including OS13, but its expression was not detectable in normal organs other than the testis and placenta. LIN28B protein was also detected in various sarcoma tissues. Knockdown of LIN28B in OS13 cells reduced tumorigenesis, decreased chemoresistance, and reversed oxidative phosphorylation function. Combination therapy consisting of a glycolysis inhibitor and low‐dose chemotherapy had antitumor effects. In conclusion, manipulation of glycolysis combined with chemotherapy might be a good adjuvant treatment for OS. Development of immunotherapy targeting LIN28B, a so‐called cancer/testis antigen, might be a good approach.