Association of circulating tumor cells and IMP3 expression with metastasis of osteosarcoma

Gene Expression Profiling and Phenotypic Characterization of Circulating Tumor Cells Derived from a Murine Osteosarcoma Model

BACKGROUND/OBJECTIVES

Osteosarcoma is an aggressive bone malignancy with high metastatic potential to the lungs. CTCs, as seeds of metastasis, play an important role in the spread of this cancer, and, therefore, their isolation, culture, and gene expression analysis promises valuable insights into the progression and metastatic cascade of osteosarcoma. The aim of this study was to isolate and culture CTCs from osteosarcoma-bearing mice and compare their migration, radioresistance, and gene expression with their parental cell line.

METHODS

CTCs from LM8-inoculated mice were isolated and cultured. The gene expression of the CTC-derived cell lines was then compared to the parental cell line. Furthermore, a Transwell assay, a clonogenic assay after irradiation, and immunohistochemical stainings were used to compare the CTC-derived cell lines with the parental cell line.

RESULTS

The CTC-derived cell lines differed significantly in gene expression from their parental cell line. 361 differentially expressed genes were identified, among which GO and KEGG analysis revealed major differences in the expression of genes related to antigen processing and presentation and extracellular matrix constituents. In addition, the CTC-derived cell lines were observed to have a higher migratory capacity and comparable radioresistance compared to the parental cell line. CD44 expression was found to be conserved in CTC-derived cell lines.

CONCLUSIONS

This study provides a comparison between CTC-derived and their parental cell lines in terms of gene expression, migration, and radioresistance. Our findings allow for further research in the field of osteosarcoma CTCs and their generation. Furthermore, the identified DEGs between CTCs and their parental cell line can serve as a reference point for targeted therapies against osteosarcoma CTCs.

The Role of Epithelial-Mesenchymal Transition in Osteosarcoma Progression: From Biology to Therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor, predominantly affecting children, adolescents, and young adults. Epithelial-mesenchymal transition (EMT), a process in which epithelial cells lose their cell-cell adhesion and gain migratory and invasive properties, has been extensively studied in various carcinomas. However, its role in mesenchymal tumors like osteosarcoma remains less explored. EMT is increasingly recognized as a key factor in the progression of osteosarcoma, contributing to tumor invasion, metastasis, and resistance to chemotherapy. This narrative review aims to provide a comprehensive overview of the molecular mechanisms driving EMT in osteosarcoma, highlighting the involvement of signaling pathways such as TGF-β, transcription factors like Snail, Twist, and Zeb, and the role of microRNAs in modulating EMT. Furthermore, we discuss how EMT correlates with poor prognosis and therapy resistance in osteosarcoma patients, emphasizing the potential of targeting EMT for therapeutic intervention. Recent advancements in understanding EMT in osteosarcoma have opened new avenues for treatment, including EMT inhibitors and combination therapies aimed at overcoming drug resistance. By integrating biological insights with clinical implications, this review underscores the importance of EMT as a critical process in osteosarcoma progression and its potential as a therapeutic target.

Circulating tumor cells in solid malignancies: From advanced isolation technologies to biological understanding and clinical relevance in early diagnosis and prognosis

Circulating tumor cells (CTCs) are shed from primary tumors and travel through the body via circulation, eventually settling to form micrometastases under favorable conditions. Numerous studies have identified CTCs as a negative prognostic indicator for survival across various cancer types. CTCs mirror the current heterogeneity and genetic and biological state of tumors, making their study invaluable for understanding tumor progression, cell senescence, and cancer dormancy. However, their isolation and characterization still poses a major challenge that limits their clinical translation. A wide array of methods, each with different levels of specificity, utility, cost, and sensitivity, have been developed to isolate and characterize CTCs. Moreover, innovative techniques are emerging to address the limitations of existing methods. In this review, we provide insights into CTC biology addressing spectra of markers employed for molecular analysis and functional characterization. It also emphasizes current label-dependent and label-independent isolation procedures, addressing their strengths and limitations. SIGNIFICANCE: A comprehensive overview of CTC biology, their molecular and functional characterization, along with their current clinical utility will help in understanding the present-day extent to which the clinical potential of CTCs is getting tapped in personalized medicine.

A revolutionary era in advancing precision immuno-oncology; role of circulating tumor cells

Despite a substantial progress in the development of strategies against cancer, cancer still remains a major global health issue due to a high recurrence rate, and severe side effects, leading basic medical scientists and clinical specialists toward more efficient diagnostics, prognostics, and therapeutics. Therefore, there is an imperative need for a comprehensive understanding on the cellular immunopathophysiology involved in the tumor microenvironment. In addition, results from a wide range of studies depicted that an aberration in the cellular mechanisms and immunopathophysiological interactions like Circulating Tumor Cells (CTCs) plays an indispensable role in the metastasis and tumor progression, revolutionizing cancer management by offering non-invasive detection methods and a real-time monitoring of tumor dynamics. Moreover, CTCs can clarify the tumor heterogeneity and the evolution of resistance mechanisms, aiding in the early detection of tumors and informing personalized treatment strategies. An increase in CTCs count can be associated with a worsened cancer prognosis, providing promising biomarkers for tumor phenotyping, tumor spreading or relapse, and monitoring the treatment response in patients with cancer. Hence, this systematic review aims to highlight the diagnostic, prognostic, and therapeutic potentials of CTCs, necessitating further investigations and an interdisciplinary collaboration among basic medical scientists and oncologists to address the current gaps in the strategies of cancer management, precisely improving patient-care and optimized clinical outcomes.

Evaluating Circulating Biomarkers for Diagnosis, Prognosis, and Tumor Monitoring in Pediatric Sarcomas: Recent Advances and Future Directions

Pediatric sarcomas present a significant challenge in oncology. There is an urgent need for improved therapeutic strategies for high-risk patients and better management of long-term side effects for those who survive the disease. Liquid biopsy is emerging as a promising tool to optimize treatment in these patients by offering non-invasive, repeatable assessments of disease status. Circulating biomarkers can provide valuable insights into tumor genetics and treatment response, potentially facilitating early diagnosis and dynamic disease monitoring. This review examines the potential of liquid biopsies, focusing on circulating biomarkers in the most common pediatric sarcomas, i.e., osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma. We also highlight the current research efforts and the necessary advancements required before these technologies can be widely adopted in clinical practice.

A comprehensive overview of liquid biopsy applications in pediatric solid tumors

Liquid biopsies are emerging as an alternative source for pediatric cancer biomarkers with potential applications during all stages of patient care, from diagnosis to long-term follow-up. While developments within this field are reported, these mainly focus on dedicated items such as a specific liquid biopsy matrix, analyte, and/or single tumor type. To the best of our knowledge, a comprehensive overview is lacking. Here, we review the current state of liquid biopsy research for the most common non-central nervous system pediatric solid tumors. These include neuroblastoma, renal tumors, germ cell tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma and other soft tissue sarcomas, and liver tumors. Within this selection, we discuss the most important or recent studies involving liquid biopsy-based biomarkers, anticipated clinical applications, and the current challenges for success. Furthermore, we provide an overview of liquid biopsy-based biomarker publication output for each tumor type based on a comprehensive literature search between 1989 and 2023. Per study identified, we list the relevant liquid biopsy-based biomarkers, matrices (e.g., peripheral blood, bone marrow, or cerebrospinal fluid), analytes (e.g., circulating cell-free and tumor DNA, microRNAs, and circulating tumor cells), methods (e.g., digital droplet PCR and next-generation sequencing), the involved pediatric patient cohort, and proposed applications. As such, we identified 344 unique publications. Taken together, while the liquid biopsy field in pediatric oncology is still behind adult oncology, potentially relevant publications have increased over the last decade. Importantly, steps towards clinical implementation are rapidly gaining ground, notably through validation of liquid biopsy-based biomarkers in pediatric clinical trials.

TROP2 is highly expressed in triple-negative breast cancer CTCs and is a potential marker for epithelial mesenchymal CTCs

Circulating tumor cells (CTCs) are the seeds of distant metastases of malignant tumors and are associated with malignancy and risk of metastasis. However, tumor cells undergo epithelial-mesenchymal transition (EMT) during metastasis, leading to the emergence of different types of CTCs. Real-time dynamic molecular and functional typing of CTCs is necessary to precisely guide personalized treatment. Most CTC detection systems are based on epithelial markers that may fail to detect EMT CTCs. Therefore, it is clinically important to identify new markers of different CTC types. In this study, bioinformatics analysis and experimental assays showed that trophoblast cell surface antigen 2 (TROP2), a target molecule for advanced palliative treatment of triple-negative breast cancer (TNBC), was highly expressed in TNBC tissues and tumor cells. Furthermore, TROP2 can promote the migration and invasion of TNBC cells by upregulating EMT markers. The specificity and potential of TROP2 as an EMT-associated marker of TNBC CTCs were evaluated by flow cytometry, immunofluorescence, spiking experiments, and a well-established CTC assay. The results indicated that TROP2 is a potential novel CTC marker associated with EMT, providing a basis for more efficacious markers that encompass CTC heterogeneity in patients with TNBC.

Quantification of circulating tumour cells over time in dogs with appendicular osteosarcoma

Enumeration of circulating tumour cells (CTC) has shown promise for prognostication and guidance of therapeutic decisions in human cancers. The objective of this study was to enumerate CTC over time in dogs with naturally occurring osteosarcoma (OSA), and to determine correlation with patient outcome. Twenty-six dogs with OSA and no evidence of metastatic disease at the time of amputation were enrolled. Dogs were assessed for lung metastases and CTC prior to and following amputation, and at each chemotherapy visit. Twenty-one dogs completed the study. Nineteen dogs were euthanized and two were alive and free of metastases. Overall survival time ranged from 88 to 1058 days (median survival time (MST) 374 days). Increased serum alkaline phosphatase activity, advanced age, and higher body weight were significantly associated with lower MST. Dogs with OSA had a mean of 356 (0 to 4443) CTC/106 leukocytes. In 12 of 15 dogs that developed radiographic evidence of metastasis, a pre-metastatic CTC spike was retrospectively detectable on average 36.5 (1-100 days) days prior to metastasis and was associated with significantly shorter MST (301 ± 64 vs. 626 ± 55 days; p = .0107). In a multivariable analysis, dogs with a CTC spike were 10× more likely to die compared with those without. These results suggest that a spike in CTC frequency precedes detection of metastasis in dogs with OSA and is associated with shorter survival. More frequent enumeration of CTC in a larger cohort of dogs with OSA may be warranted.