the abc subfamily a transporters multifaceted players with incipient potentialities in cancer

Abstract Overexpression of ATP-binding cassette (ABC) transporters is a cause of drug resistance in a plethora of tumors. More recent evidence indicates additional contribution of these transporters to other processes, such as tumor cell dissemination and metastasis, thereby extending their possible roles in tumor progression. While the role of some ABC transporters, such as ABCB1, ABCC1 and ABCG2, in multidrug resistance is well documented, the mechanisms by which ABC transporters affect the proliferation, differentiation, migration and invasion of cancer cells are still poorly defined and are frequently controversial. This review, summarizes recent advances that highlight the role of subfamily A members in cancer. Emerging evidence highlights the potential value of ABCA members as biomarkers of risk and response in different tumors, but information is disperse and very little is known about their possible mechanisms of action. The only clear evidence is that ABCA members are involved in lipid metabolism and homeostasis. In particular, the relationship between ABCA1 and cholesterol is becoming evident in different fields of biology, including cancer. In parallel, emerging findings indicate that cholesterol, the main component of cell membranes, can influence many physiological and pathological processes, including cell migration, cancer progression and metastasis. This review aims to link the dispersed knowledge regarding the relationship of ABCA members with lipid metabolism and cancer in an effort to stimulate and guide readers to areas that the writers consider to have significant impact and relevant potentialities

Synovial Sarcoma Preclinical Modeling: Integrating Transgenic Mouse Models and Patient-Derived Models for Translational Research

Synovial sarcomas (SyS) are rare malignant tumors predominantly affecting children, adolescents, and young adults. The genetic hallmark of SyS is the t(X;18) translocation encoding the SS18-SSX fusion gene. The fusion protein interacts with both the BAF enhancer and polycomb repressor complexes, and either activates or represses target gene transcription, resulting in genome-wide epigenetic perturbations and altered gene expression. Several experimental in in vivo models, including conditional transgenic mouse models expressing the SS18-SSX fusion protein and spontaneously developing SyS, are available. In addition, patient-derived xenografts have been estab-lished in immunodeficient mice, faithfully reproducing the complex clinical heterogeneity. This review focuses on the main molecular features of SyS and the related preclinical in vivo and in vitro models. We will analyze the different conditional SyS mouse models that, after combination with some of the few other recurrent alterations, such as gains in BCL2, Wnt- -catenin signaling, FGFR family, or loss of PTEN and SMARCB1, have provided additional insight into the mechanisms of synovial sarcomagenesis. The recent advancements in the understanding of SyS biology and improvements in preclinical modeling pave the way to the development of new epigenetic drugs and immunotherapeutic approaches conducive to new treatment options

Innovative Breakthroughs for the Treatment of Advanced and Metastatic Synovial Sarcoma

Simple Summary Synovial sarcoma (SyS) is a rare malignant soft tissue sarcoma bearing the chromosomal translocation t(X;18), which encodes the fusion oncoprotein SS18::SSX. More than 80% of the patients, mainly young in age, are initially diagnosed with localized disease with a 5-year survival rate of 70-80%. Metastatic relapse occurs in 50% of the cases. Advanced, unresectable, or metastatic disease shows a poor prognosis with a 5-year survival rate below 10%, representing an urgent clinical issue. This review will focus on: (i) current front-line therapies; (ii) alternative treatments in second line and beyond settings; and (iii) new epigenetic and immunological strategies. The improved understanding of the SyS molecular biology coupled with the recent development of innovative technologies, such as proteolysis targeting chimera (PROTAC) protein degraders or adoptive transfer of engineered immune cells, is offering new promising tools. Clinical trial results underline the need for accurate patient selection based on genetic and tumor immune microenvironment signatures. Synovial sarcoma (SyS) is a rare aggressive soft tissue sarcoma carrying the chromosomal translocation t(X;18), encoding the fusion transcript SS18::SSX. The fusion oncoprotein interacts with both BAF enhancer complexes and polycomb repressor complexes, resulting in genome-wide epigenetic perturbations and a unique altered genetic signature. Over 80% of the patients are initially diagnosed with localized disease and have a 5-year survival rate of 70-80%, but metastatic relapse occurs in 50% of the cases. Advanced, unresectable, or metastatic disease has a 5-year survival rate below 10%, representing a critical issue. This review summarizes the molecular mechanisms behind SyS and illustrates current treatments in front line, second line, and beyond settings. We analyze the use of immune check point inhibitors (ICI) in SyS that do not behave as an ICI-sensitive tumor, claiming the need for predictive genetic signatures and tumor immune microenvironment biomarkers. We highlight the clinical translation of innovative technologies, such as proteolysis targeting chimera (PROTAC) protein degraders or adoptive transfer of engineered immune cells. Adoptive cell transfer of engineered T-cell receptor cells targeting selected cancer/testis antigens has shown promising results against metastatic SyS in early clinical trials and further improvements are awaited from refinements involving immune cell engineering and tumor immune microenvironment enhancement

Altered modulation of lamin A/C-HDAC2 interaction and p21 expression during oxidative stress response in HGPS

Defects in stress response are main determinants of cellular senescence and organism aging. In fibroblasts from patients affected by Hutchinson-Gilford progeria, a severe LMNA-linked syndrome associated with bone resorption, cardiovascular disorders, and premature aging, we found altered modulation of CDKN1A, encoding p21, upon oxidative stress induction, and accumulation of senescence markers during stress recovery. In this context, we unraveled a dynamic interaction of lamin A/C with HDAC2, an histone deacetylase that regulates CDKN1A expression. In control skin fibroblasts, lamin A/C is part of a protein complex including HDAC2 and its histone substrates; protein interaction is reduced at the onset of DNA damage response and recovered after completion of DNA repair. This interplay parallels modulation of p21 expression and global histone acetylation, and it is disrupted by LMNAmutations leading to progeroid phenotypes. In fact, HGPS cells show impaired lamin A/C-HDAC2 interplay and accumulation of p21 upon stress recovery. Collectively, these results link altered physical interaction between lamin A/C and HDAC2 to cellular and organism aging. The lamin A/C-HDAC2 complex may be a novel therapeutic target to slow down progression of progeria symptoms

Sunitinib Exerts In Vitro Immunomodulatory Activity on Sarcomas via Dendritic Cells and Synergizes With PD-1 Blockade

Background: High-grade sarcomas are a heterogeneous group of aggressive tumors arising in bone and soft tissues. After relapse, treatment options are limited. The multi-targeted receptor tyrosine kinase inhibitors (TKIs) sunitinib and inhibitor of PD-1 (anti-PD-1) nivolumab have shown antitumor activity in selected subtypes. In this study, we examine the role of TKIs and PD-1 based therapy in in vitro cocultures of sarcoma. Methods: The human osteosarcoma (SaOS-2) and synovial sarcoma (SYO-1) cell lines were treated with sunitinib. After cell death and proliferation assessment, expression of PD-L1 was analyzed by flow cytometry. Sunitinib-treated sarcoma cells were cocultured with dendritic cells (DCs), and the phenotype of mature DCs was determined by flow cytometry. Mature DCs were cultured with autologous T cells. PD-1 expression on T cells, their proliferation, T regulatory cell (Tregs) induction and IFN-γ production, before and after nivolumab exposure, were analyzed. Results: Along with its anti-proliferative and direct pro-apoptotic effect on sarcoma cell lines, sunitinib prompted PD-L1 upregulation on sarcoma cells. Interestingly, sunitinib-treated sarcoma cells drive DCs to full maturation and increase their capacity to induce sarcoma-reactive T cells to produce IFN-γ. Conversely, no effect on T cell proliferation and T cell subpopulation composition was observed. Moreover, both bone and synovial sarcoma cell lines induced Tregs through DCs but sunitinib treatment completely abrogated Treg induction. Finally, sarcoma cell lines induced PD-1 upregulation on both effector T cells and Tregs when loaded into DCs, providing a rationale for using PD-1 blockade. Indeed, PD-1 blockade by nivolumab synergized with sunitinib in inducing IFN-γ-producing effector T cells. Conclusions: Taken together, our in vitro data indicate that the treatment of sarcoma cells with sunitinib can exert significant changes on immune cell subsets toward immune activation, leading to DC-based cross-priming of IFN-γ-producing effector T cells and reduced Treg induction. PD-1 blockade with nivolumab has a synergistic effect with sunitinib, supporting the use of TKI and anti-PD-1 approach in sarcomas, and perhaps in other cancers. DC-targeted drugs, including toll-like receptor 3 inhibitors and CD47 inhibitors, are under development and our preclinical model might help to better design their clinical application

Insulin-Like Growth Factor 2 mRNA-Binding Protein 3 Modulates Aggressiveness of Ewing Sarcoma by Regulating the CD164-CXCR4 Axis

Ewing sarcoma (EWS) is the second most common bone and soft tissue-associated malignancy in children and young adults. It is driven by the fusion oncogene EWS/FLI1 and characterized by rapid growth and early metastasis. We have previously discovered that the mRNA binding protein IGF2BP3 constitutes an important biomarker for EWS as high expression of IGF2BP3 in primary tumors predicts poor prognosis of EWS patients. We additionally demonstrated that IGF2BP3 enhances anchorage-independent growth and migration of EWS cells suggesting that IGF2BP3 might work as molecular driver and predictor of EWS progression. The aim of this study was to further define the role of IGF2BP3 in EWS progression. We demonstrated that high IGF2BP3 mRNA expression levels correlated with EWS metastasis and disease progression in well-characterized EWS tumor specimens. EWS tumors with high IGF2BP3 levels were characterized by a specific gene signature enriched in chemokine-mediated signaling pathways. We also discovered that IGF2BP3 regulated the expression of CXCR4 through CD164. Significantly, CD164 and CXCR4 colocalized at the plasma membrane of EWS cells upon CXCL12 stimulation. We further demonstrated that IGF2BP3, CD164, and CXCR4 expression levels correlated in clinical samples and the IGF2BP3/CD164/CXCR4 signaling pathway promoted motility of EWS cells in response to CXCL12 and under hypoxia conditions. The data presented identified CD164 and CXCR4 as novel IGF2BP3 downstream functional effectors indicating that the IGF2BP3/CD164/CXCR4 oncogenic axis may work as critical modulator of EWS aggressiveness. In addition, IGF2BP3, CD164, and CXCR4 expression levels may constitute a novel biomarker panel predictive of EWS progression

Polymorphic variants of IGF2BP3 and SENCR have an impact on predisposition and/or progression of Ewing sarcoma

Ewing sarcoma (EWS), the second most common malignant bone tumor in children and adolescents, occurs abruptly without clear evidence of tumor history or progression. Previous association studies have identified some inherited variants associated with the risk of developing EWS but a common picture of the germline susceptibility to this tumor remains largely unclear. Here, we examine the association between thirty single nucleotide polymorphisms (SNPs) of the IGF2BP3, a gene that codes for an oncofetal RNA-binding protein demonstrated to be important for EWS patient's risk stratification, and five SNPs of SENCR, a long non-coding RNA shown to regulate IGF2BP3. An association between polymorphisms and EWS susceptibility was observed for three IGF2BP3 SNPs - rs112316332, rs13242065, rs12700421 - and for four SENCR SNPs - rs10893909, rs11221437, rs12420823, rs4526784 -. In addition, IGF2BP3 rs34033684 and SENCR rs10893909 variants increased the risk for female respect to male subgroup when carried together, while IGF2BP3 rs13242065 or rs76983703 variants reduced the probability of a disease later onset (> 14 years). Moreover, the absence of IGF2BP3 rs10488282 variant and the presence of rs199653 or rs35875486 variant were significantly associated with a worse survival in EWS patients with localized disease at diagnosis. Overall, our data provide the first evidence linking genetic variants of IGF2BP3 and its modulator SENCR to the risk of EWS development and to disease progression, thus supporting the concept that heritable factors can influence susceptibility to EWS and may help to predict patient prognosis

Metformin as an adjuvant drug against pediatric sarcomas: hypoxia limits therapeutic effects of the drug.

Metformin, a well-known insulin-sensitizer commonly used for type 2 diabetes therapy, has recently emerged as potentially very attractive drug also in oncology. It is cheap, it is relatively safe and many reports have indicated effects in cancer prevention and therapy. These desirable features are particularly interesting for pediatric sarcomas, a group of rare tumors that have been shown to be dependent on IGF and insulin system for pathogenesis and progression. Metformin exerts anti-mitogenic activity in several cancer histotypes through several molecular mechanisms. In this paper, we analyzed its effects against osteosarcoma, Ewing sarcoma and rhabdomyosarcoma, the three most common pediatric sarcomas. Despite in vitro metformin gave remarkable antiproliferative and chemosensitizing effects both in sensitive and chemoresistant cells, its efficacy was not confirmed against Ewing sarcoma xenografts neither as single agent nor in combination with vincristine. This discrepancy between in vitro and in vivo effects may be due to hypoxia, a common feature of solid tumors. We provide evidences that in hypoxia conditions metformin was not able to activate AMPK and inhibit mTOR signaling, which likely prevents the inhibitory effects of metformin on tumor growth. Thus, although metformin may be considered a useful complement of conventional chemotherapy in normoxia, its therapeutic value in highly hypoxic tumors may be more limited. The impact of hypoxia should be considered when novel therapies are planned for pediatric sarcomas

High Expression of Complement Component 5 (C5) at Tumor Site Associates with Superior Survival in Ewing's Sarcoma Family of Tumour Patients

Background. Unlike in most adult-onset cancers, an association between typical paediatric neoplasms and inflammatory triggers is rare. We studied whether immune system-related genes are activated and have prognostic significance in Ewing's sarcoma family of tumors (ESFTs). Method. Data analysis was performed on gene expression profiles of 44 ESFT patients, 11 ESFT cell lines, and 18 normal skeletal muscle samples. Differential expression of 238 inflammation and 299 macrophage-related genes was analysed by t-test, and survival analysis was performed according to gene expression. Results. Inflammatory genes are activated in ESFT patient samples, as 38 of 238 (16%) inflammatory genes were upregulated (P < 0.001) when compared to cell lines. This inflammatory gene activation was characterized by significant enrichment of macrophage-related gene expression with 58 of 299 (19%) of genes upregulated (P < 0.001). High expression of complement component 5 (C5) correlated with better event-free (P = 0.01) and overall survival (P = 0.004) in a dose-dependent manner. C5 and its receptor C5aR1 expression was verified at protein level by immunohistochemistry on an independent ESFT tumour tissue microarray. Conclusion. Immune system-related gene activation is observed in ESFT patient samples, and prognostically significant inflammatory genes (C5, JAK1, and IL8) for ESFT were identified

Targets for cancer therapy in childhood sarcomas

Development of chemotherapeutic treatment modalities resulted in a dramatic increase in the survival of children with many types of cancer. Still, in case of some pediatric cancer entities including rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma, survival of patients remains dismal and novel treatment approaches are urgently needed. Therefore, based on the concept of targeted therapy, numerous potential targets for the treatment of these cancers have been evaluated pre-clinically or in some cases even clinically during the last decade. This review gives an overview over many different potential therapeutic targets for treatment of these childhood sarcomas, including receptor tyrosine kinases, intracellular signaling molecules, cell cycle and apoptosis regulators, proteasome, hsp90, histone deacetylases, angiogenesis regulators and sarcoma specific fusion proteins. The large number of potential therapeutic targets suggests that improved comparability of pre-clinical models might be necessary to prioritize the most effective ones for future clinical trials