PMCID
string
Title
string
Sentences
string
PMC10669128
Preclinical Models of Visceral Sarcomas
The molecular biology of sarcomas is poorly understood, especially the interplay among signaling pathways, as well as the epigenetic modifications and regulatory RNA sequences.
PMC10669128
Preclinical Models of Visceral Sarcomas
Patient-derived 3D sarcoma models could be useful to recapitulate the three-dimensional structure of these neoplasms, clarifying the complex crosstalk between tumor cells and their microenvironment, and contributing to personalized medicine development .
PMC10669128
Preclinical Models of Visceral Sarcomas
Despite most of the available three-dimensional spheroid cultures and organoids being relevant to the study of skeletal sarcomas, 3D models have also been developed for visceral sarcomas.
PMC10669128
Preclinical Models of Visceral Sarcomas
In this regard, Escudero and colleagues assessed the effect of eribulin (an antitumor agent approved for advanced liposarcoma treatment) on inhibiting the proliferation, migration, and invasion of LPSs and LMSs in 3D spheroid cell cultures.
PMC10669128
Preclinical Models of Visceral Sarcomas
For the first time, they explored erilubin’s action under 3D conditions in LMSs and LPSs, demonstrating an increase in the GI50 (growth inhibitory concentration by 50%) values to a nanomolar range compared to in a 2D cellular context .
PMC10669128
Preclinical Models of Visceral Sarcomas
Roohani and colleagues conducted a pilot study on a STS 3D model developed from patient-derived cell cultures (PD3D) of an untreated localized UPS.
PMC10669128
Preclinical Models of Visceral Sarcomas
They assessed a decrease in tumor cell viability at different time points (four and eight days after treatment) using increasing doses of photon and proton radiation.
PMC10669128
Preclinical Models of Visceral Sarcomas
PD3D therefore could be a valuable tool to facilitate translational studies toward individualized subtype-specific radiotherapy in STS patients .
PMC10669128
Preclinical Models of Visceral Sarcomas
Nonetheless, it is still unclear how three-dimensional models will allow better predictability for treatments that target the microenvironment or involve radiation.
PMC10669128
Preclinical Models of Visceral Sarcomas
Furthermore, the available cell lines inadequately represent sarcoma diversity, and primarily encompass the most common groups like osteosarcomas, rhabdomyosarcomas, and leiomyosarcomas while lacking representation of rarer subtypes .
PMC10669128
Preclinical Models of Visceral Sarcomas
Therefore, new cell lines are urgently needed in the field of sarcoma research .
PMC10669128
Preclinical Models of Visceral Sarcomas
Cancer stem cells (CSCs) in soft tissue sarcomas can be reprogrammed toward a pluripotent state, using similar methods to those applied to normal cells (e.g., induced pluripotent stem cell (iPSC) technology) .
PMC10669128
Preclinical Models of Visceral Sarcomas
Recently, iPSCs have emerged as a valuable tool for disease modeling, already applied in the field of genetic and oncological disease.
PMC10669128
Preclinical Models of Visceral Sarcomas
This is due to the possibility of replicating a cancer phenotype within the appropriate cell lineage.
PMC10669128
Preclinical Models of Visceral Sarcomas
By generating genome-edited isogenic iPSC lines in correspondence to the oncogenic drivers within a specific tissue, it would be possible to faithfully reproduce the neoplasm in vitro.
PMC10669128
Preclinical Models of Visceral Sarcomas
This could facilitate the study of the targeted treatment susceptibility of various tumor histotypes .
PMC10669128
Preclinical Models of Visceral Sarcomas
While targeting CSCs is crucial for all cancer types, in STSs, it is more challenging since these neoplasms are less common and exhibit high cellular and molecular heterogeneity.
PMC10669128
Preclinical Models of Visceral Sarcomas
However, STSs’ unique characteristics offer opportunities for further exploration, such as the identification of common CSC signatures across all STSs, which can be therapeutically targeted .
PMC10669128
Preclinical Models of Visceral Sarcomas
By combining CRISPR-Cas9 technologies with HDR (homology-directed repair) in human embryonic stem cells (hES), Vanoli and colleagues developed an innovative approach to investigating the cell of origin in human cancers without a clear line of differentiation, including sarcomas with chromosomal translocations.
PMC10669128
Preclinical Models of Visceral Sarcomas
They also demonstrated that chromosomal translocations are involved in hES differentiation in human embryonic-stem-derived mesenchymal progenitor cells (hES-MP), clarifying the role of gene fusion in sarcomagenesis under conditional expression .
PMC10669128
Preclinical Models of Visceral Sarcomas
While several stem cell-based models of synovial sarcoma and skeletal sarcomas have been developed, especially for the study of osteosarcoma and Ewing’s sarcoma , visceral sarcomas need to be further explored.
PMC10669128
Preclinical Models of Visceral Sarcomas
Among the available animal models in cancer research, human tumor xenografts are the most widely used.
PMC10669128
Preclinical Models of Visceral Sarcomas
They consist of the implantation of tumor cells into immunocompromised mice, either under the skin or into the same organ type of origin (Figure 1A).
PMC10669128
Preclinical Models of Visceral Sarcomas
Athymic nude mice, severe combined immunodeficient (SCID) mice, or other immunocompromised mice can readily accept xenografts .
PMC10669128
Preclinical Models of Visceral Sarcomas
Several studies have been conducted on cell-derived xenograft (CDX) models to assess both the target therapy effectiveness and oncogenic activity in STSs.
PMC10669128
Preclinical Models of Visceral Sarcomas
An example is the xenograft model investigated by Floris and colleagues, obtained from the IM-sensitive GIST882 cell line.
PMC10669128
Preclinical Models of Visceral Sarcomas
For the first time, they used this nude xenograft model to evaluate the effects of the HDACi panobinostat on human GISTs with different oncogenic KIT mutations.
PMC10669128
Preclinical Models of Visceral Sarcomas
Panobinostat reduced proliferation and increased apoptosis in all xenografts, proving its anti-tumor activity .
PMC10669128
Preclinical Models of Visceral Sarcomas
Another STS xenograft model, applied to leiomyosarcomas, is the one established by Zhang‘s group by injecting SCID mice with SK-LMS-1 cells previously transfected with VEGF165 .
PMC10669128
Preclinical Models of Visceral Sarcomas
Approximately 21–25% of patients affected by STSs display VEGF overexpression, which correlates with a more advanced tumor grade and a worse prognosis .
PMC10669128
Preclinical Models of Visceral Sarcomas
Based on the established role of VEGF and its receptor VEGFR in angiogenesis, the authors tried to better clarify the role of VEGF165 in STS growth, metastasis, and chemoresistance.
PMC10669128
Preclinical Models of Visceral Sarcomas
The obtained VEGR165-overexpressing xenograft model revealed the significant impact of VEGF expression on STSs’ ability to grow and metastasize, and the anti-VEGFR2 monoclonal antibody’s effects on enhancing the doxorubicin response .
PMC10669128
Preclinical Models of Visceral Sarcomas
CDX models provide the advantage of replicating human tumor biology, despite the possibility of clone selection, which might not accurately represent the human disease .
PMC10669128
Preclinical Models of Visceral Sarcomas
An alternative to cell line xenografts is the transplantation of small pieces of human-derived tumor samples into mice, obtaining so-called patient-derived xenograft (PDX) models (Figure 1B).
PMC10669128
Preclinical Models of Visceral Sarcomas
In this case, the advantage is represented by the close resemblance of the model to the primary tumor sample .
PMC10669128
Preclinical Models of Visceral Sarcomas
For instance, copy number alterations observed in STS PDXs are also detected in sarcoma patients, suggesting that these alterations correlate with actual tumor progression rather than experimental model alterations .
PMC10669128
Preclinical Models of Visceral Sarcomas
Several models have been successfully established, achieving an overall engraftment success rate of 32% to 69% and efficiently reproducing the genetic and phenotypic characteristics of the original tumor .
PMC10669128
Preclinical Models of Visceral Sarcomas
PDXs can be considered superior to classical cell-line-derived xenografts in accurately predicting patient response to therapy .
PMC10669128
Preclinical Models of Visceral Sarcomas
In this regard, Gebreyohannes and colleagues proved the anti-tumor efficacy of cabozantinib, a novel tyrosine kinase inhibitor, by reducing tumor growth, proliferation, and angiogenesis in IM-sensitive and IM-resistant PDX models of GISTs .
PMC10669128
Preclinical Models of Visceral Sarcomas
Similarly, Van Looy’s team demonstrated the effectiveness of three PI3K inhibitors combined with imatinib in reducing tumor volumes and enhancing apoptosis in GIST PDXs .
PMC10669128
Preclinical Models of Visceral Sarcomas
Analogous research has been conducted on sarcoma xenograft models to explore the antitumor effects of target therapies.
PMC10669128
Preclinical Models of Visceral Sarcomas
This is the case for Li and colleagues, who established two PDX models of DDLPS by implanting pieces of patient-derived sarcomas inro athymic nude NMRI mice.
PMC10669128
Preclinical Models of Visceral Sarcomas
Significantly decreased proliferation and angiogenesis inhibition characterized all the xenografts treated with the TKRi pazopanib .
PMC10669128
Preclinical Models of Visceral Sarcomas
Zuco’s group conducted a direct comparison between the first-in-class XPO1 inhibitor selinexor and doxorubicin, the standard front-line therapy for sarcomas, in three DDLPS PDXs.
PMC10669128
Preclinical Models of Visceral Sarcomas
They demonstrated selinexor’s potential as a therapeutic agent for DDLPS, given its superiority in terms of the umor response in all PDXs when compared to doxorubicin, regardless of the MDM2 amplification and histological differentiations .
PMC10669128
Preclinical Models of Visceral Sarcomas
The few preclinical models of leiomyosarcoma and the lack of fidelity of the established LMS cell lines to their mesenchymal neoplasm of origin limit the translational understanding of the disease.
PMC10669128
Preclinical Models of Visceral Sarcomas
In this regard, Hemming and colleagues characterized LMS PDX models assessing that, across multiple xenograft passages, the parental tumor histological appearance, copy number variation, and transcriptional program were maintained.
PMC10669128
Preclinical Models of Visceral Sarcomas
Additionally, LMS PDXs were susceptible to cyclin-dependent kinase (CDK) inhibition, which alters the oncogenic transcriptional program driven by E2F and hinders tumor growth.
PMC10669128
Preclinical Models of Visceral Sarcomas
Thus, CDK inhibitors can be a valuable therapeutic strategy for patients with LMS .
PMC10669128
Preclinical Models of Visceral Sarcomas
As previously discussed, PDXs are useful to assess the effects of combined therapies.
PMC10669128
Preclinical Models of Visceral Sarcomas
This was further supported by Perez’s team, who demonstrated the potential therapeutic strategies of doxorubicin and olaparib against sarcomas in UPS PDXs.
PMC10669128
Preclinical Models of Visceral Sarcomas
The combined treatment efficacy in tumors with high levels of pH2AX and MAP17 suggested that both biomarkers could potentially identify patients who would benefit more from the therapy .
PMC10669128
Preclinical Models of Visceral Sarcomas
Similarly, Stacchioti’s group investigated the preclinical antitumor activity of EPZ-011989, an EZH2 inhibitor, in INI1-deficient proximal-type epithelial sarcoma (ES) PDXs.
PMC10669128
Preclinical Models of Visceral Sarcomas
EPZ-011989, gemcitabine, and a doxorubicin–ifosfamide combination exhibited comparable antitumor activity in treated mice, supporting their clinical use as effective therapies.
PMC10669128
Preclinical Models of Visceral Sarcomas
Moreover, EZH2 was confirmed as a viable therapeutic target in ESs, suggesting autophagy as a possible protective mechanism against EZH2 inhibition .
PMC10669128
Preclinical Models of Visceral Sarcomas
Interestingly, an established patient-derived orthotopic nude mouse xenograft of a retroperitoneal STS was developed by Hiroshima and colleagues.
PMC10669128
Preclinical Models of Visceral Sarcomas
This model recapitulated the histology of the original tumor better than the same subcutaneous ectopic model .
PMC10669128
Preclinical Models of Visceral Sarcomas
Hence, PDXs are largely used for the assessment of human tumor biology and have a broad range of applications in preclinical drug testing, in therapeutic target identification, and for the establishment of stable xenograft cell lines .
PMC10669128
Preclinical Models of Visceral Sarcomas
Furthermore, these models could represent an option for personalized medicine strategies, allowing for direct testing of potential drug treatments on a model matching the patient .
PMC10669128
Preclinical Models of Visceral Sarcomas
However, recent advances in immunotherapy highlighted the importance of immune response in cancer progression and treatment, and thus the need to develop new PDX models to investigate human cancer and immune system interactions .
PMC10669128
Preclinical Models of Visceral Sarcomas
Wang’s team established an in vivo humanized mouse xenograft model by transplanting human CD34+ hematopoietic progenitor and stem cells into NGS mice, originating humanized NGS (HuNGS) mice with human hematopoietic and immune systems.
PMC10669128
Preclinical Models of Visceral Sarcomas
Then, they implanted PDXs of various cancers (sarcoma, non-small cell lung cancer, bladder, triple-negative breast cancer) into HuNGSs.
PMC10669128
Preclinical Models of Visceral Sarcomas
Treatment with PD-1 checkpoint inhibitor pemrolizumab significantly inhibited the tumor growth of PDX tumors in HuNGS mice, assessing the potential utility of the model for preclinical immunotherapy research .
PMC10669128
Preclinical Models of Visceral Sarcomas
Patient-derived models (PDMs) are widely applied in cancer research, drug development, and clinical applications.
PMC10669128
Preclinical Models of Visceral Sarcomas
Since PDMs are directly derived from patients, they can predict treatment response and could help to identify the best personalized treatment strategy .
PMC10669128
Preclinical Models of Visceral Sarcomas
Research findings support that sarcoma patient-derived cells predict STS patient response to therapy since these models preserve the genetic characteristics of the original tumor and the association between drug sensitivity and patient response .
PMC10669128
Preclinical Models of Visceral Sarcomas
Nonetheless, there are still challenges and limitations to overcome, such as costs and time, as well as tumor heterogeneity, which might not be represented by PDMs, potentially affecting the accuracy of drug testing .
PMC10669128
Preclinical Models of Visceral Sarcomas
Among other animal models used in sarcoma research, it is worthwhile to mention the genome-engineered mouse model (GEMM), in which mice display an altered genetic profile by mutating, deleting, or overexpressing one or several oncogenes (Figure 1C).
PMC10669128
Preclinical Models of Visceral Sarcomas
GEMMs allow us to monitor the effects of induced genetic alterations over time and to evaluate tumor response to treatment in vivo .
PMC10669128
Preclinical Models of Visceral Sarcomas
Conditional transgenic mice expressing oncogenic human fusion genes, as well as immunodeficient mice that enable the growth of human tumor cells or tumor fragments cultured in vitro, have allowed the implementation of the available preclinical models for translational research .
PMC10669128
Preclinical Models of Visceral Sarcomas
An example of an in vivo visceral sarcoma model is represented by the MMTV-CR-1 transgenic mice generated by Strizzi and colleagues, in which CR-1 transgene expression is regulated by the MMTV (the mouse mammary tumor virus) long terminal repeat promoter and leads to uterine leiomyosarcoma development.
PMC10669128
Preclinical Models of Visceral Sarcomas
CR-1 plays a role in uterine tumor onset via the direct activation of c-src and Akt or via crosstalk with the canonical Wnt signaling pathway .
PMC10669128
Preclinical Models of Visceral Sarcomas
Many transgenic mouse models have also been generated to study gastrointestinal stromal tumors.
PMC10669128
Preclinical Models of Visceral Sarcomas
For instance, Sommer’s group created a knock-in mouse with an exon 11 KIT-activating mutation (KITV558 deletion), previously found in the case of human familial GIST syndrome.
PMC10669128
Preclinical Models of Visceral Sarcomas
Through this model, they reproduced gastrointestinal pathology in mice with remarkable penetrance, demonstrating that the constitutive activation of KIT signaling is pivotal and sufficient to cause neoplastic growth in mice .
PMC10669128
Preclinical Models of Visceral Sarcomas
Likewise, Rubin’s team developed a homozygous knock-in mouse model harboring a KIT-activating mutation K641E, resulting in GIST development with 100% penetrance.
PMC10669128
Preclinical Models of Visceral Sarcomas
They also showed the model effectiveness for the study of KIT pathway activation, GIST pathogenesis, and preclinical validation of GIST therapies and drug response .
PMC10669128
Preclinical Models of Visceral Sarcomas
Regarding the study of undifferentiated pleomorphic sarcoma, for the first time, Buchakjian and colleagues generated a viral Cre-mediated TRP53/PTEN mouse model, by injecting adenoviral Cre recombinase into TRP53flox/flox/PTENflox/flox lox–stop–lox luciferase mice.
PMC10669128
Preclinical Models of Visceral Sarcomas
All the injected mice developed STSs, identified for 93% as invasive pleomorphic sarcomas characterized by lymphocytic infiltrate (64%) and PD-L1 expression (71%).
PMC10669128
Preclinical Models of Visceral Sarcomas
The model could represent a valuable tool for liposarcoma preclinical studies since the homozygous loss of TRP53 and PTEN in mouse adipose tissue also characterizes this sarcoma histotype .
PMC10669128
Preclinical Models of Visceral Sarcomas
Within the realm of liposarcoma research, Pèrez-Mancera’s group generated CHOP and FUS ± CHOP transgenic mice, by introducing CHOP or the FUS-CHOP transgene into mouse genomes.
PMC10669128
Preclinical Models of Visceral Sarcomas
Interestingly, only the latter mouse group developed LPSs.
PMC10669128
Preclinical Models of Visceral Sarcomas
This demonstrated the critical role of the FUS domain in the liposarcoma pathogenesis and pioneeringly proved the in vivo correlation between gene fusions and solid tumor onset .
PMC10669128
Preclinical Models of Visceral Sarcomas
A few years later, the same group generated double-transgenic FUS-CHOP mice to investigate the significance of the FUS-CHOP interaction.
PMC10669128
Preclinical Models of Visceral Sarcomas
As a result, FUS expression in CHOP transgenic mice restored liposarcoma development, indicating that the FUS and CHOP domains cooperate in mutual liposarcoma restoration .
PMC10669128
Preclinical Models of Visceral Sarcomas
As previously mentioned, unfortunately, angiosarcomas lack valid clinical models that allow new therapy development.
PMC10669128
Preclinical Models of Visceral Sarcomas
However, Salter’s team generated an autochthonous AS mouse model driven by p53 deregulation in VE-cadherin-expressing endothelial cells, using Cdh5-Cre mice.
PMC10669128
Preclinical Models of Visceral Sarcomas
AS arose in mice with a penetrance of 100% upon homozygous deletion of TRP53.
PMC10669128
Preclinical Models of Visceral Sarcomas
The re-implantation of AS fragments from Cdh5-Cre, Trp53 mice yielded a reliable and rapid angiosarcoma model.
PMC10669128
Preclinical Models of Visceral Sarcomas
Moreover, transferring tumor fragments within mice allowed them to establish a novel AS model suitable for preclinical studies and for new therapy development .
PMC10669128
Preclinical Models of Visceral Sarcomas
In this review, we summarize the most used in vitro and in vivo models adopted for the study of visceral sarcomas (Figure 2).
PMC10669128
Preclinical Models of Visceral Sarcomas
However, all of them present both advantages and limitations.
PMC10669128
Preclinical Models of Visceral Sarcomas
Sarcoma cell lines have a central role in cancer research, as they can be easily employed to develop new potential drugs, allowing rapid identification of compounds with anti-cancer activity.
PMC10669128
Preclinical Models of Visceral Sarcomas
Moreover, cell lines can be genetically manipulated to study the effects of specific mutations on tumor growth and invasiveness, and to investigate the molecular mechanisms of visceral sarcomas.
PMC10669128
Preclinical Models of Visceral Sarcomas
Nonetheless, not all the therapeutic approaches can be tested in vitro.
PMC10669128
Preclinical Models of Visceral Sarcomas
Additionally, cell lines might not accurately represent tumors’ microenvironment complexity and their interactions with stromal and immune cells.
PMC10669128
Preclinical Models of Visceral Sarcomas
Thus, the immune system and the effects of drugs targeting the microenvironment cannot be evaluated in cultured cell lines .
PMC10669128
Preclinical Models of Visceral Sarcomas
Furthermore, in vitro studies cannot fully recapitulate the genetic and epigenetic landscape of primary tumors.
PMC10669128
Preclinical Models of Visceral Sarcomas
Finally, when maintained in cultures, cells display gene expression and cellular behavior changes over time, which might lead to biased results.
PMC10669128
Preclinical Models of Visceral Sarcomas
Therefore, in vivo models can compensate for in vitro weaknesses.