Dedifferentiated Liposarcoma Cell Research Articles

Abstract 5922: Characterization of the biological effects of a quadruplex-interacting molecule in dedifferentiated liposarcoma cells

Abstract G-rich nucleic acid sequences can assume, under physiologic conditions, non-B secondary structures called G-quadruplexes (G4). The human genome contains thousands of putative quadruplex forming sequences (PQS), of which telomeres are the most extensively studied. PQS are frequently found in the promoters of oncogenes and transcription factors rather than in tumor suppressor or housekeeping genes, indicating an evolutionary selection of these elements based on gene function and suggesting a pivotal role of G4 in the regulation of gene expression. These observations have provided the rationale to explore G4 targeting as a therapeutic approach in cancer. Several small molecules have been indeed designed and characterized as G4-ligands (G4-L), most of them showing a “multiple-target” binding modality. Dedifferentiated liposarcoma (DDLPS) is a non-lipogenic disease characterized by aggressive local growth and multifocal local recurrences and the ability to elicit distant metastases. At the molecular level, DDLPS is marked by the amplification of the 12q13-q15 chromosomal region, leading to the abnormal expression of the MDM2 oncogene. The gene has emerged as an actionable therapeutic target and, recently, PQS within its promoter have been reported to fold into G4 structures. In addition, in our previous study, we observed that pathways related to telomere maintenance are remarkably up-modulated in DDLPS. These findings open a new avenue to explore the therapeutic potential of G4-L in this malignancy. In the present study, the biological activity of a tetra-substituted naphthalene diimide (NDI) G4-L derivative (SOP1812/QN-302) has been characterized in two patient-derived DDLPS cell lines. In particular, the exposure of DDLPS cells to increasing concentrations of SOP1812 resulted in a marked cytotoxic activity in vitro, with IC50 values within the sub-micromolar range (~0.3 μM). Moreover, DDLPS cells treated with equitoxic amounts of the compound were characterized by an 80-90% inhibition of telomerase activity and a remarkable perturbation in the MDM2-p53 feedback loop, leading to a pronounced accumulation of basal and phosphorylated (S15/S46/S392) p53 protein. These effects were paralleled by a 3-4 time increase in the number of γ-H2AX foci, the appearance of the cleaved form of PARP-1 and a pronounced inhibition of cell growth over time. Altogether, our findings indicate that targeting G4 structures by quadruplex-interacting molecules may represent a potential novel and effective therapeutic strategy in DDLPS. Citation Format: Eisa Naghshineh, Beatrice Tosoni, Lorenzo Di Pietro, Sandro Pasquali, Nadia Zaffaroni, Stephen Neidle, Sara N. Richter, Marco Folini. Characterization of the biological effects of a quadruplex-interacting molecule in dedifferentiated liposarcoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5922.

Notch signaling regulates a metabolic switch through inhibiting PGC-1α and mitochondrial biogenesis in dedifferentiated liposarcoma.

Human dedifferentiated liposarcoma (DDLPS) is a rare but lethal cancer with no driver mutations being identified, hampering the development of targeted therapies. We and others recently reported that constitutive activation of Notch signaling through overexpression of the Notch1 intracellular domain (NICDOE) in murine adipocytes leads to tumors resembling human DDLPS. However, the mechanisms underlying the oncogenic functions of Notch activation in DDLPS remains unclear. Here, we show that Notch signaling is activated in a subset of human DDLPS and correlates with poor prognosis and expression of MDM2, a defining marker of DDLPS. Metabolic analyses reveal that murine NICDOE DDLPS cells exhibit markedly reduced mitochondrial respiration and increased glycolysis, mimicking the Warburg effect. This metabolic switch is associated with diminished expression of peroxisome proliferator-activated receptor gamma coactivator 1α (Ppargc1a, encoding PGC-1α protein), a master regulator of mitochondrial biogenesis. Genetic ablation of the NICDOE cassette rescues the expression of PGC-1α and mitochondrial respiration. Similarly, overexpression of PGC-1α is sufficient to rescue mitochondria biogenesis, inhibit the growth and promote adipogenic differentiation of DDLPS cells. Together, these data demonstrate that Notch activation inhibits PGC-1α to suppress mitochondrial biogenesis and drive a metabolic switch in DDLPS.

Abstract 5993: Dissecting the role of CDK4 in liposarcoma

Abstract Background: Liposarcoma (LPS) encompass one of most common soft tissue sarcoma (STS) histological subtypes accounting for 15% of all cases. They can be divided into four entities including atypical lipomatous tumor or well-differentiated LPS (ALT/WDLPS), dedifferentiated LPS (DDLPS), myxoid LPS (MLPS) and pleomorphic LPS (PLS). Their heterogeneity is reflected in their morphology, molecular landscape, prognosis and clinical behavior. Current treatment options for localized disease include surgery, (neo)adjuvant radiotherapy and chemotherapy; for the metastatic setting chemotherapy represents the cornerstone but its role needs to be elucidated. The unavailability of predictive biomarkers makes the management of these mesenchymal diseases even more challenging. Recent evidences have shed light on the key role of cyclin-dependent kinase 4 (CDK4) in cancer cells proliferation. Methods: This study involved 21 adult patients affected by liposarcoma (n= 5 ALT/WDLPS and n= 16 DDLPS). IHC analyses of CDK4 and MDM2 were performed on FFPE surgically resected specimens by experienced sarcoma pathologists. Moreover, a patient-derived DDLPS cell line was established and pharmacological profiling was performed. Next, standard and innovative drugs currently used for LPS management were assessed in both 2D and 3D culture systems. Finally, in silico analyses based on public repositories on STS were carried out including 260 sarcoma patients. Results: IHC results highlighted an higher expression of CDK4 and MDM2 biomarkers in DDLPS compared to ALT/WDLSP. Moreover, although CDK4 and MDM2 are codified by the same genomic region, their expression did not correlate (e.g. 100% of CDK4 and 2% of MDM2 in the same patient). Therefore we hypothesized that even exhibiting a low MDM2 expression, a patient could benefit from CDK4 inhibition. Furthermore, our data showed that in DDLPS cases CDK4 expression ranged from 90% to 100% in spermatic cord, skin and abdomen while it ranged from 5% to 50% in the retroperitoneum. The above observations prompted us to hypothesize a correlation of CDK4 expression with specific anatomical sites. Moreover, pharmacological profiling showed a synergistic effect exerted by sequential treatment with palbociclib and some chemotherapeutics including trabectedin, dacarbazine, eribulin and lenvatinib. Indeed we observed a 10% increase in cell proliferation inhibition compared to standard treatment. In addition, in silico analyses revealed the role of CDK4 as negative prognostic biomarker for PFS and OS in STS. Conclusions: Our study highlighted the promising role of CDK4 in the management of LPS patients. In particular, we pointed out encouraging results of sequential treatment combining CDK4 inhibitor palbociclib and chemotherapy. Furthermore, preliminary analyses highlighted the involvement of this biomarker as a potential prognostic tool for STS. Citation Format: Silvia Vanni, Graziana Gallo, Valentina Fausti, Giacomo Miserocchi, Chiara Liverani, Chiara Spadazzi, Claudia Cocchi, Chiara Calabrese, Giovanni De Luca, Massimo Bassi, Manlio Gessaroli, Angelo Campobassi, Federica Pieri, Giorgio Ercolani, Davide Cavaliere, Lorena Gurrieri, Nada Riva, Giovanni Martinelli, Laura Mercatali, Alessandro De Vita. Dissecting the role of CDK4 in liposarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5993.

Abstract 4777: Exploring ferroptosis pathway for the development of therapeutic strategy in liposarcoma

Abstract Background: Liposarcoma (LPS) is one of the most common soft tissue sarcoma (STS) subtypes. Both well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS) have 12q13-15 amplification. Mouse double minute 2 homolog (MDM2) is one of the most important oncogenes within this region. Ferroptosis is a unique type of necrotic cell death featured accumulation of lipid-based reactive oxygen species (ROS) derived from the oxidative modification of phospholipid membranes. Cysteine metabolism is the critical part of ferroptosis regulation. Cystine-glutamate antiporter (system xc-; xCT), encoded by two subcomponents, the solute carrier family 7 member 11 (SLC7A11) and SLC3A2, is responsible for cystine supply from extra-cellular environment. Imported cystine is then reduced to cysteine, a key component of tripeptide glutathione (GSH). Glutathione peroxidase 4 (GPX4) requires GSH to repair lipid peroxidation and prevent ferroptosis. Inactivation of GPX4, either through cystine deprivation due to xCT inhibitor erastin, or by GPX4 inhibitor Ras-selective lethal small molecule 3 (RSL3), will lead to accumulation of lipid-based ROS, and eventually ferroptosis cell death. The tumor suppressor p53 (TP53) could suppress the expression of SLC7A11 and induce ferroptosis. TP53 could also indirectly suppress 3-hydroxy-3-methyl-glutaryl (HMG)-coenzyme A (CoA) reductase (HMGCR) activity, a key pathway for generation of biomolecules with anti-ferroptosis property. MDM2, the key oncogene in DDLPS, and homolog MDM4 could facilitate ferroptotic death in TP53-dependent or -independent mechanisms. Methods: We explored public domain database to identify possible aberrations of ferroptosis-related genes in DDLPS. We then examined the sensitivity of DDLPS cell lines to possible ferroptosis-inducing agents. Furthermore, we used nutlin-3, a MDM2 inhibitor, to modulate the MDM2 expression in DDLPS cell line, and explored the potential synergistic effect of nutlin-3 with ferroptosis-inducing agents. Finally, we used immunoblotting study to reveal the potential mechanism responsible to possible synergistic effect. Results: Expression level of GPX4 is significantly lower in DDLPS than adipose tissue and WDLPS, and DPP4 was general higher in LPS than adipose tissue. HMGCR, SLC7A11 and SLC3A2 were mostly up-regulated in LPS in comparison with benign counterpart. Both DDLPS cell lines showed sensitivity to erastin and RSL3. In addition, nutlin-3 could exert synergistic ferroptosis-inducing effect and cytotoxicity with erastin and RSL3 in sequential manner. Furthermore, nultin-3 treatment could upregulate SLC3A2 with altered cystine/glutamate exchange in DDLPS cell lines, indicating possible mechanism responsible for nultin-3 resistance and the synergistic effect of nultin-3 with erastin or RSL3. Conclusion: Our study showed that modulation of ferroptosis is a potential treatment strategy in DDLPS. Citation Format: Chueh-Chuan Yen, San-Chi Chen, Chih-Hsueh Chen, Jir-You Wang, Chao-Ming Chen, Po-Kuei Wu, Muh-Hwa Yang. Exploring ferroptosis pathway for the development of therapeutic strategy in liposarcoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4777.

Three dimensional models of dedifferentiated liposarcoma cell lines: scaffold-based and scaffold-free approaches.

Sarcomas are rare malignancies, the number of reports is limited, and this rarity makes further research difficult even though liposarcoma is one of major sarcomas. 2D cell culture remains an important role in establishing basic tumor biology research, but its various shortcomings and limitations are still of concern, and it is now well-accepted that the behavior of 3D-cultured cells is more reflective of in vivo cellular responses compared to 2D models. This study aimed to establish 3D cell culture of liposarcomas using two different methods: scaffold-based (Matrigel extracellular matrix [ECM] scaffold method) and scaffold-free (Ultra-low attachment [ULA] plate). Lipo246, Lipo224 and Lipo863 cell lines were cultured, and distinctive differences in structures were observed in Matrigel 3D model: Lipo224 and Lipo863 formed spheroids, whereas Lipo246 grew radially without forming spheres. In ULA plate approaches, all cell lines formed spheroids, but Lipo224 and Lipo863 spheroids showed bigger size and looser aggregation than Lipo246. Formalin fixed, paraffin embedded (FFPE) blocks were obtained from all 3D models, confirming the spheroid structures. The expression of MDM2, Ki-67 positivity and MDM2 amplification were confirmed by IHC and DNAscope™, respectively. Protein and DNA were extracted from all samples and MDM2 upregulation was confirmed by western blot and qPCR analysis. After treatment with MDM2 inhibitor SAR405838, DDLPS spheroids demonstrated different sensitivity patterns from 2D models. Taken together, we believed that 3D models would have a possibility to provide us a new predictability of efficacy and toxicity, and considered as one important process in in vitro pre-clinical phase prior to moving forward to clinical trials.

Transcriptome analysis identifies TODL as a novel lncRNA associated with proliferation, differentiation, and tumorigenesis in liposarcoma through FOXM1

Liposarcoma, the most common soft tissue sarcoma, is a group of fat cell mesenchymal tumors with different histological subtypes. The dysregulation of long non-coding RNAs (lncRNAs) has been observed in human cancers including a few studies in sarcoma. However, the global transcriptome analysis and potential role of lncRNAs remain unexplored in liposarcoma. The present investigation uncovers the transcriptomic profile of liposarcoma by RNA sequencing to gain insight into the global transcriptional changes in liposarcoma. Our RNA sequencing analysis has identified that many oncogenic lncRNAs are differentially expressed in different subtypes of liposarcoma including MALAT1, PVT1, SNHG15, LINC00152, and MIR210HG. Importantly, we identified a highly overexpressed, unannotated, and novel lncRNA in dedifferentiated liposarcomas. We have named it TODL, transcript overexpressed in dedifferentiated liposarcoma. TODL lncRNA displayed significantly higher expression in dedifferentiated liposarcoma cell lines and patient samples. Interestingly, functional studies revealed that TODL lncRNA has an oncogenic function in liposarcoma cells by regulating proliferation, cell cycle, apoptosis, differentiation, and tumorigenesis in the murine model. Silencing of TODL lncRNA highlighted the enrichment of several key oncogenic signaling pathways including cell cycle, transcriptional misregulation, FOXM1 network, p53 signaling, PLK1 signaling, FoxO, and signaling Aurora signaling pathways. RNA pull-down assay revealed the binding of TODL lncRNA with FOXM1, an oncogenic transcription factor, and the key regulator of the cell cycle. Silencing of TODL lncRNA also induces adipogenesis in dedifferentiated liposarcomas. Altogether, our finding indicates that TODL could be utilized as a novel, specific diagnostic biomarker, and a pharmacological target for therapeutic development in controlling aggressive and metastatic dedifferentiated liposarcomas.

Establishment and characterization of a novel patient-derived cell line of dedifferentiated liposarcoma, NCC-DDLPS6-C1

Dedifferentiated liposarcoma (DDLPS) is morphologically characterized by well-differentiated liposarcomas associated with high-grade non-lipogenic sarcoma and molecularly characterized by the coamplification of MDM2 and CDK4(12q14-15). DDLPS is highly aggressive, and effective systemic chemotherapy has not been developed yet. In this study, we established a novel DDLPS cell line, NCC-DDLPS6-C1, as a potential tool for the development of novel therapies. NCC-DDLPS6-C1 cells were established from surgically resected tumor tissues of a patient with DDLPS. Amplification and overexpression of MDM2 and CDK4 were observed in NCC-DDLPS6-C1 cells. NCC-DDLPS6-C1 cells proliferated rapidly, invaded aggressively, and formed spheroids. Moreover, NCC-DDLPS6-C1 cells formed tumors in mice. These observations suggested that the malignant potentials that may reflect the original features of DDLPS were retained in the NCC-DDLPS6-C1. Anticancer drugs that significantly reduced the proliferation of NCC-DDLPS6-C1 cells were identified by drug library screening. Thus, NCC-DDLPS6-C1 may recapitulate the original genotypes and phenotypes, and we conclude that the NCC-DDLPS6-C1 cell line is a useful resource for the study of DDLPS.

Expression of the preadipocyte marker ZFP423 is dysregulated between well-differentiated and dedifferentiated liposarcoma

BackgroundWell-differentiated and dedifferentiated liposarcomas are rare soft tissue tumors originating in adipose tissue that share genetic abnormalities but have significantly different metastatic potential. Dedifferentiated liposarcoma (DDLPS) is highly aggressive and has an overall 5-year survival rate of 30% as compared to 90% for well-differentiated liposarcoma (WDLPS). This discrepancy may be connected to their potential to form adipocytes, where WDLPS is adipogenic but DDLPS is adipogenic-impaired. Normal adipogenesis requires Zinc Finger Protein 423 (ZFP423), a transcriptional coregulator of Perixosome Proliferator Activated Receptor gamma (PPARG2) mRNA expression that defines committed preadipocytes. Expression of ZFP423 in preadipocytes is promoted by Seven-In-Absentia Homolog 2 (SIAH2)-mediated degradation of Zinc Finger Protein 521 (ZFP521). This study investigated the potential role of ZFP423, SIAH2 and ZFP521 in the adipogenic potential of WDLPS and DDLPS.MethodsHuman WDLPS and DDLPS fresh and paraffin-embedded tissues were used to assess the gene and protein expression of proadipogenic regulators. In parallel, normal adipose tissue stromal cells along with WDLPS and DDLPS cell lines were cultured, genetically modified, and induced to undergo adipogenesis in vitro.ResultsImpaired adipogenic potential in DDLPS was associated with reduced ZFP423 protein levels in parallel with reduced PPARG2 expression, potentially involving regulation of ZFP521. SIAH2 protein levels did not define a clear distinction related to adipogenesis in these liposarcomas. However, in primary tumor specimens, SIAH2 mRNA was consistently upregulated in DDLPS compared to WDLPS when assayed by fluorescence in situ hybridization or real-time PCR.ConclusionsThese data provide novel insights into ZFP423 expression in adipogenic regulation between WDLPS and DDLPS adipocytic tumor development. The data also introduces SIAH2 mRNA levels as a possible molecular marker to distinguish between WDLPS and DDLPS.

Establishment and characterization of NCC-DDLPS5-C1: a novel patient-derived cell line of dedifferentiated liposarcoma.

Dedifferentiated liposarcoma (DDLPS) is a highly aggressive subtype of liposarcoma that is morphologically defined as a transition from a well-differentiated lipomatous component to a non-lipogenic one. Curative therapy for DDLPS is complete resection, and the benefits of current systemic chemotherapy remain marginal. Although DDLPS is molecularly characterized by co-amplification of MDM2 and CDK4 (12q14-15) and detailed genomic analyses have been conducted by multiple research groups, the effects of molecular targeted drugs are marginal, and novel therapeutic modalities are required. Although patient-derived cell lines are pivotal for cancer research, no DDLPS cell lines are currently available from public cell repositories. Accordingly, in this study, we established a novel DDLPS cell line, NCC-DDLPS5-C1, using surgically resected tumor tissues from a patient with DDLPS. NCC-DDLPS5-C1 cells exhibited typical gene amplification, overexpression of MDM2 and CDK4, and other DNA copy number alterations. The NCC-DDLPS5-C1 cells were capable of rapid cell proliferation, aggressive invasion, and spheroid formation, but not tumor formation in mice. We reported the utility of NCC-DDLPS5-C1 cells for a drug-response assay to detect anticancer drugs that significantly attenuated cell proliferation. Thus, we concluded that the NCC-DDLPS5-C1 cell line could be a useful resource for the study of DDLPS. Considering the diversity of disease in terms of clinical outcomes, continuous efforts are required to develop more patient-derived cancer models with different clinical and pathological backgrounds.

A High-Content Screen for C/EBPα Expression Identifies Novel Therapeutic Agents in Dedifferentiated Liposarcoma.

Dedifferentiated liposarcoma (DDLS), one of the most common and aggressive sarcomas, infrequently responds to chemotherapy. DDLS survival and growth depend on underexpression of C/EBPα, a tumor suppressor and transcriptional regulator controlling adipogenesis. We sought to screen and prioritize candidate drugs that increase C/EBPα expression and may therefore serve as differentiation-based therapies for DDLS. We screened known bioactive compounds for the ability to restore C/EBPα expression and inhibit proliferation selectively in two DDLS cell lines but not in normal adipose-derived stem cells (ASC). Selected hits' activity was validated, and the mechanism of the most potent, SN-38, was investigated. The in vivo efficacy of irinotecan, the prodrug of SN-38, was evaluated in DDLS xenograft models. Of 3,119 compounds, screen criteria were met by 19. Validation experiments confirmed the DDLS selectivity of deguelin, emetine, and SN-38 and showed that they induce apoptosis in DDLS cells. SN-38 had the lowest IC50 (approximately 10 nmol/L), and its pro-apoptotic effects were countered by knockdown of CEBPA but not of TP53. Irinotecan significantly inhibited tumor growth at well-tolerated doses, induced nuclear expression of C/EBPα, and inhibited HIF1α expression in DDLS patient-derived and cancer cell line xenograft models. In contrast, doxorubicin, the most common treatment for nonresectable DDLS, reduced tumor growth by 30% to 50% at a dose that caused weight loss. This high-content screen revealed potential treatments for DDLS. These include irinotecan, which induces apoptosis of DDLS cells in a C/EBPα-dependent, p53-independent manner, and should be clinically evaluated in patients with advanced DDLS.

Establishment and Characterization of NCC-DDLPS4-C1: A Novel Patient-Derived Cell Line of Dedifferentiated Liposarcoma.

Dedifferentiated liposarcoma (DDLPS) is a highly malignant sarcoma characterized by the co-amplification of MDM2 and CDK4. Although systemic chemotherapy is recommended for unresectable or metastatic cases, DDLPS is insensitive to conventional chemotherapy, leading to an unfavorable prognosis. Therefore, novel treatment methods are urgently required. Patient-derived cell lines are essential in preclinical studies. Recently, large-scale screening studies using a number of cell lines have been actively conducted for the development of new therapeutic drugs. However, the DDLPS cell line cannot be obtained from public cell banks owing to its rarity, hindering screening studies. As such, novel DDLPS cell lines need to be established. Accordingly, this study aimed to establish a novel DDLPS cell line from surgical specimens. The cell line was named NCC-DDLPS4-C1. NCC-DDLPS4-C1 cells retained copy number alterations corresponding to the original tumors. Further, the cells demonstrated constant growth, spheroid formation, and equivalent invasiveness to MG63 osteosarcoma cells. We also conducted drug screening and integrated the results with those of the previously reported DDLPS cell lines. Consequently, we identified the histone deacetylase inhibitor romidepsin as a novel candidate drug. In conclusion, the NCC-DDLPS4-C1 cell line is a useful tool for the basic study of DDLPS.

CCNDBP1, a Prognostic Marker Regulated by DNA Methylation, Inhibits Aggressive Behavior in Dedifferentiated Liposarcoma via Repressing Epithelial Mesenchymal Transition.

The present study aimed to explore the prognostic value, function, and mechanism of CCNDBP1 in dedifferentiated liposarcoma (DDL). Immunohistochemistry staining was used to analyze the protein expression of CCNDBP1 in tissue specimens. After silencing CCNDBP1 in LPS853 and overexpressing CCNDBP1 in LPS510, CCK-8, clone formation, transwell migration, and invasion assays were used to detect cell proliferation, migration, and invasion ability. CCNDBP1-induced cell apoptosis was analyzed by flow cytometry. The altered expression of epithelial-mesenchymal transition (EMT)-related proteins were detected by Western blot. The methylation, gene expression, and clinical data of 58 samples with DDL were analyzed using the cancer genome atlas (TCGA) database. Low expression of CCNDBP1 was associated with a poor prognosis of patients with DDL and was considered an independent prognostic factor of the progression-free survival (PFS). CCNDBP1 significantly inhibited the clone formation, proliferation, migration, and invasion of cancer cells in vitro and promoted cancer cell apoptosis. CCNDBP1 could repress the pathological EMT, thereby inhibiting the malignant behaviors of DDL cells. The high degree of DNA methylation sites cg05194114 and cg22184989 could decrease the expression of CCNDBP1 and worsen the prognosis of DDL patients. This is the first study reporting that CCNDBP1 is a tumor suppressor gene of DDL and putative prognostic marker in DDL patients. CCNDBP1 might inhibit the ability of cell proliferation and invasion by repressing pathological EMT, and the expression of CCNDBP1 could be regulated by DNA methylation in DDL.

Abstract 2438: Genetic activation of JUN fuels the core regulatory circuitry of de-differentiated liposarcoma

Abstract Background: As a high-grade neoplasm of connective tissues, de-differentiated liposarcoma (DDLPS) is featured by genomic amplification of MDM2, CDK4 and JUN. Super-enhancer-driven master transcription factors (RUNX1, FOSL2 and MYC) establish a core feed-forward transcriptional circuit underpinning the DDLPS malignancy. However, an important question remains unanswered: how do genomic insults interact with epigenetic dysregulation in this disease? Methods: We performed ChIP-seq analysis to map loading of transcription factors and histone marks on chromatin in DDLPS cells. Functional assays following genetic manipulation of target genes were conducted to explore their disease relevance. Results: Genomic activation of JUN represents a promising prognostic marker for DDLPS. Meanwhile, JUN locus engaged excessive H3K27ac signals in both DDLPS tissues and cells, while a markedly lower level of H3K27ac deposition was observed in normal adipose tissues, adipocytes and MSCs. JUN formed a complex with FOSL2 and other co-factors in active chromatin, especially super-enhancers. Silencing of either JUN or its co-factors disrupted the core regulatory circuitry, which was accompanied by strong deleterious impacts on both cell viability and tumorigenicity. As BET bromodomain proteins dictate transcriptionally active chromatin, targeted degradation of BET proteins by PROTAC compounds exerted potent inhibitory effects on both JUN cistrome and DDLPS development. Conclusion: Our study reveals that amplification and overexpression of JUN contribute to DDLPS development. DDLPS-associated genomic abnormalities collaborate with BET proteins to fuel disease-driving core regulatory circuitry. Citation Format: Ye Chen, Pushkar Dakle, Tuan Zea Tan, Ruby Yu-Tong Lin, Mark E. Puhaindran, Sigal Gery, Liang Xu, Phillip H. Koeffler. Genetic activation of JUN fuels the core regulatory circuitry of de-differentiated liposarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2438.

Abstract 1067: PDK-1 targeting with SNS-510 in sarcoma

Abstract Soft tissue sarcomas are heterogeneous mesenchymal neoplasms and account for 1% of all cancers in adults. Over 50 sarcomas subtypes have been classified and many have limited treatment options some of which include surgery, chemotherapy and radiation. 3-phosphoinositide dependent protein kinase 1 (PDK1) is overexpressed in many cancers, suggesting a role for PDK1 in cancer progression. In addition, PDK1 has been identified as a key modifier of acquired resistance to CDK4/6 inhibitors. In order to interrogate this in sarcoma, we elected to test SNS-510 a potent, orally bioavailable PDK1 inhibitor against a broad range of sarcoma cell lines (leiomyosarcoma, dedifferentiated liposarcoma, Ewing's sarcoma, osteosarcoma, chondrosarcoma and synovial sarcoma) as well as dedifferentiated liposarcoma cell lines with acquired resistance to ribociclib, which are also cross resistant to palbociclib. All the cell lines expressed PDK1 and, as measured by WST-8 cell proliferation assay, nearly all the cell lines were sensitive to the drug, with IC50s generally between 250 to 500nM. Leiomyosarcoma cell lines (SK-LMS, SK-UT1, SK-UT1b) were seen to be most sensitive to SNS-510 with IC50s determined to be between 50-100nM. In contrast, synovial sarcoma cell lines (SYO-1 and HSSY-II) exhibited relative resistance to SNS-510 with IC50s determined to be > 500nM. As assessed by western blot, SNS-510 exhibited a dose dependent inhibition of the PDK-1/RSK2/AKT pathway with inhibition of p-RSK2(244), p-AKT(308), and pS6(235/236). SNS-510 induced a dose-dependent G1 cell cycle arrest. This was associated with inhibition of p-RB(780) and suppression of cyclin D1 and cyclin E1. The exception to this was the synovial cell lines for which there was no inhibition of p-RB despite inhibition of p-RSK, p-AKT and p-S6. When combined with palbociclib in both the CDK4/6 sensitive (LS141 and DDLS) and CDK4/6 resistant liposarcoma cells (RES.LS141 and RES.DDLS), we observed enhanced inhibition of proliferation with a synergistic effect, as defined by the Chou-Talalay method. These results would suggest a role for PDK-1 targeting with SNS-510 in sarcoma and consideration of combination strategies, especially with CDK4/6 inhibitors in both CDK4/6 sensitive and resistant dedifferentiated liposarcoma. Citation Format: Elgilda Musi, Pietro Taverna, Gary K. Schwartz. PDK-1 targeting with SNS-510 in sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1067.

Comprehensive serum and tissue microRNA profiling in dedifferentiated liposarcoma.

Sarcoma is a rare cancer with several subtypes; therefore, our understanding of the pathogenesis of sarcoma is limited, and designing effective treatments is difficult. Circulating microRNAs (miRNAs), including exosomal miRNAs, have attracted attention as biomarkers in cancer. However, the roles of miRNAs and exosomes in sarcoma remain unclear. The present analysis of tissue and serum miRNA expression in osteosarcoma, Ewing's sarcoma and dedifferentiated liposarcoma (DDLPS) identified miR-1246, −4532, −4454, −619-5p and −6126 as biomarkers for DDLPS. These miRNAs were highly expressed in human DDLPS cell lines and exosomes, suggesting that they are secreted from DDLPS tissues. The present results suggested that specific miRNAs may be used as biomarkers for early diagnosis or treatment targets in DDLPS.

Novel Therapeutic Insights in Dedifferentiated Liposarcoma: A Role for FGFR and MDM2 Dual Targeting.

Simple SummaryWell-differentiated/dedifferentiated liposarcomas (WDLPS/DDLPS) are the most frequent soft tissue sarcomas. Despite the hopes raised by some targeted therapies, effective well-tolerated treatments for DDLPS are still lacking. Small-molecule FGFR inhibitors are currently evaluated in advanced clinical trials including the potent FDA-approved pan-FGFR inhibitor erdafitinib. We provide the first analysis of FGFR1-4 expression and their prognostic value in a series of 694 WDLPS/DDLPS samples. We identified FGFR1 and FGFR4 as prognostic biomarkers. We demonstrated erdafitinib efficacy and showed that erdafitinib combination with the MDM2 antagonist idasanutlin was highly synergistic in vitro and in vivo. The clinical relevance of our findings was supported by our data on a patient with DDLPS refractory to multiple lines of treatment whose tumor was stabilized for 12 weeks on erdafitinib. These data provide a rationale to use FGFR expression as a biomarker to select patients for clinical trials investigating FGFR inhibitors and to test combined erdafitinib and idasanutlin.We aimed to evaluate the therapeutic potential of the pan-FGFR inhibitor erdafitinib to treat dedifferentiated liposarcoma (DDLPS). FGFR expression and their prognostic value were assessed in a series of 694 samples of well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS). The effect of erdafitinib—alone or in combination with other antagonists—on tumorigenicity was evaluated in vitro and in vivo. We detected overexpression of FGFR1 and/or FGFR4 in a subset of WDLPS and DDLPS and demonstrated correlation of this expression with poor prognosis. Erdafitinib treatment reduced cell viability, inducing apoptosis and strong inhibition of the ERK1/2 pathway. Combining erdafitinib with the MDM2 antagonist RG7388 exerted a synergistic effect on viability, apoptosis, and clonogenicity in one WDLPS and two DDLPS cell lines. Efficacy of this combination was confirmed in vivo on a DDLPS xenograft. Importantly, we report the efficacy of erdafitinib in one patient with refractory DDLPS showing disease stabilization for 12 weeks. We provide evidence that the FGFR pathway has therapeutic potential for a subset of DDLPS and that an FGFR1/FGFR4 expression might constitute a powerful biomarker to select patients for FGFR inhibitor clinical trials. In addition, we show that combining erdafitinib with RG7388 is a promising strategy for patients with DDLPS that deserves further investigation in the clinical setting.

Establishment and characterization of NCC-DDLPS1-C1: a novel patient-derived cell line of dedifferentiated liposarcoma.

Dedifferentiated liposarcoma (DDLPS) is one of the four subtypes of liposarcomas; it is characterized by the amplification of the 12q13-15 region, which includes MDM2 and CDK4 genes. DDLPS has an extremely high local recurrence rate and is refractory to chemotherapy and radiation, which leads to poor prognosis. Therefore, a novel therapeutic strategy should be urgently established for improving the prognosis of DDLPS. Although patient-derived cell lines are important tools for basic research, there are no DDLPS cell lines available from public cell banks. Here, we report the establishment of a novel DDLPS cell line. Using the surgically resected tumor tissue from a patient with DDLPS, we established a cell line and named it NCC-DDLPS1-C1. The NCC-DDLPS1-C1 cells contained 12q13-15, 1p32, and 1q23 amplicons and highly expressed MDM2 and CDK4 proteins. NCC-DDLPS-C1 cells exhibited constant growth, spheroid formation, aggressive invasion, and tumorigenesis in mice. By screening a drug library, we identified that the proteasome inhibitor, bortezomib, had inhibitory effects on the proliferation of NCC-DDLPS1-C1 cells. We concluded that the NCC-DDLPS1-C1 cell line may serve as a useful tool for basic and pre-clinical studies of DDLPS.

MDM2 Antagonists Induce a Paradoxical Activation of Erk1/2 through a P53-Dependent Mechanism in Dedifferentiated Liposarcomas: Implications for Combinatorial Strategies.

The MDM2 gene is amplified in dedifferentiated liposarcoma (DDLPS). Treatment with MDM2 antagonists is a promising strategy to treat DDLPS; however, drug resistance is a major limitation when these drugs are used as a single agent. This study examined the impact of MDM2 antagonists on the mitogen-activated protein kinase (MAPK) pathway in DDLPS and investigated the potential synergistic activity of a MAPK kinase (MEK) inhibitor in combination with MDM2 antagonists. We identified a synergistic effect and identified the mechanism behind it. Combination effects of MDM2 antagonists and a MEK inhibitor were analyzed in a patient-derived xenograft mouse model and in DDLPS and leiomyosarcoma cell lines using different cell proliferation assays and immunoblot analysis. MDM2 antagonist (RG7388)-resistant IB115 [P4] cells and p53-silenced DDLPS cells were also established to understand the importance of functional p53. We found that MDM2 antagonists induced an upregulation of phosphorylated extracellular signal-regulated kinase (p-ERK) in DDLPS cells. The upregulation of p-ERK occurred due to mitochondrial translocation of p53, which resulted in increased production of reactive oxygen species, causing the activation of receptor tyrosine kinases (RTKs). Activated RTKs led to the activation of the downstream MEK/ERK signaling pathway. Treatment with a MEK inhibitor resulted in decreased expression of p-ERK, causing significant anti-tumor synergy when combined with MDM2 antagonists. Our results provide a framework for designing clinical studies of combination therapies in DDLPS patients.

MDM2-Dependent Rewiring of Metabolomic and Lipidomic Profiles in Dedifferentiated Liposarcoma Models.

Dedifferentiated liposarcoma (DDLPS) is an aggressive mesenchymal cancer marked by amplification of MDM2, an inhibitor of the tumor suppressor TP53. DDLPS patients with higher MDM2 amplification have lower chemotherapy sensitivity and worse outcome than patients with lower MDM2 amplification. We hypothesized that MDM2 amplification levels may be associated with changes in DDLPS metabolism. Six patient-derived DDLPS cell line models were subject to comprehensive metabolomic (Metabolon) and lipidomic (SCIEX 5600 TripleTOF-MS) profiling to assess associations with MDM2 amplification and their responses to metabolic perturbations. Comparing metabolomic profiles between MDM2 higher and lower amplification cells yielded a total of 17 differentially abundant metabolites across both panels (FDR < 0.05, log2 fold change < 0.75), including ceramides, glycosylated ceramides, and sphingomyelins. Disruption of lipid metabolism through statin administration resulted in a chemo-sensitive phenotype in MDM2 lower cell lines only, suggesting that lipid metabolism may be a large contributor to the more aggressive nature of MDM2 higher DDLPS tumors. This study is the first to provide comprehensive metabolomic and lipidomic characterization of DDLPS cell lines and provides evidence for MDM2-dependent differential molecular mechanisms that are critical factors in chemoresistance and could thus affect patient outcome.

Cracking the riddle of dedifferentiated liposarcoma: is EV-MDM2 a key?

Dedifferentiated liposarcoma (DDLPS) is molecularly characterized by wt p53 and MDM2 gene amplification causing MDM2 protein over-production, the key oncogenic process in DDLPS. Commonly located in fat-bearing retroperitoneal areas, almost 60% of DDLPS patients undergo multifocal recurrence, typically amenable to palliative treatment only, and occasionally develop distant metastasis. These factors lead to an abysmal 10% 10 year overall survival rate. Tumor cell-derived extracellular vesicles (EVs) can facilitate loco-regional malignancy dissemination by depositing molecular factors that participate in the development of pre-metastatic niches for tumor cell implantation and growth. High number of MDM2 DNA molecules was identified within EVs from DDLPS patient serum (ROC vs normal; 0.95) as well as from DDLPS cell lines. This MDM2 DNA could be transferred to preadipocytes (P-a), a major and ubiquitous cellular component of the DDLPS tumor microenvironment (TME), with subsequent P-a production of matrix metalloproteinase 2 (MMP2), a critical component in the metastatic cascade. From here the hypothesis that the DDLPS microenvironment (specifically P-a cells) may participate in DDLPS recurrence events. Since multifocal loco-regional DDLPS spreading is the main cause of the remarkably high lethality of this disease, a better understanding of the underlying oncogenic processes and their regulatory mechanisms is essential to improve the outcome of this devastating disease.