Combined targeting of mTOR and c-MET signaling pathways for effective management of epithelioid sarcoma

Translational Aspects of Epithelioid Sarcoma: Current Consensus

Epithelioid sarcoma (EpS) is an ultra-rare malignant soft-tissue cancer mostly affecting adolescents and young adults. EpS often exhibits an unfavorable clinical course with fatal outcome in ∼50% of cases despite aggressive multimodal therapies combining surgery, chemotherapy, and irradiation. EpS is traditionally classified in a more common, less aggressive distal (classic) type and a rarer aggressive proximal type. Both subtypes are characterized by a loss of nuclear INI1 expression, most often following homozygous deletion of its encoding gene, SMARCB1-a core subunit of the SWI/SNF chromatin remodeling complex. In 2020, the EZH2 inhibitor tazemetostat was the first targeted therapy approved for EpS, raising new hopes. Still, the vast majority of patients did not benefit from this drug or relapsed rapidly. Further, other recent therapeutic modalities, including immunotherapy, are only effective in a fraction of patients. Thus, novel strategies, specifically targeted to EpS, are urgently needed. To accelerate translational research on EpS and eventually boost the discovery and development of new diagnostic tools and therapeutic options, a vibrant translational research community has formed in past years and held two international EpS digital expert meetings in 2021 and 2023. This review summarizes our current understanding of EpS from the translational research perspective and points to innovative research directions to address the most pressing questions in the field, as defined by expert consensus and patient advocacy groups.

Pharmacotherapeutic strategies for epithelioid sarcoma: are we any closer to a non-surgical cure?

INTRODUCTION

Epithelioid sarcoma (ES) is a rare soft tissue sarcoma subtype, predominantly occurring in children and young adults. Despite optimal management of localized disease, approximately 50% of patients develop advanced disease. The management of advanced ES remains challenging due to limited response to conventional chemotherapy and despite novel oral EZH2 inhibitors that have better tolerability but similar efficacy to chemotherapy.

AREAS COVERED

We performed a literature review using the PubMed (MEDLINE) and Web of Science databases. We have focused on the role of chemotherapy, targeted agents such as EZH2 inhibitors, potential new targets and immune checkpoint inhibitors and combinations of therapies currently undergoing clinical investigation.

EXPERT OPINION

ES is a soft tissue sarcoma with a heterogeneous pathological, clinical, and molecular presentation. In the current era of precision medicine, more trials with targeted therapies and a combination of chemotherapy or immunotherapy with targeted therapies are required to establish optimal treatment for ES.

Receptor tyrosine kinase inhibitors in cancer

Targeted therapy is a new cancer treatment approach, involving drugs that particularly target specific proteins in cancer cells, such as receptor tyrosine kinases (RTKs) which are involved in promoting growth and proliferation, Therefore inhibiting these proteins could impede cancer progression. An understanding of RTKs and the relevant signaling cascades, has enabled the development of many targeted drug therapies employing RTK inhibitors (RTKIs) some of which have entered clinical application. Here we discuss RTK structures, activation mechanisms and functions. Moreover, we cover the potential effects of combination drug therapy (including chemotherapy or immunotherapy agents with one RTKI or multiple RTKIs) especially for drug resistant cancers.

An Overview of Epithelial-to-Mesenchymal Transition and Mesenchymal-to-Epithelial Transition in Canine Tumors: How Far Have We Come?

Historically, pre-clinical and clinical studies in human medicine have provided new insights, pushing forward the contemporary knowledge. The new results represented a motivation for investigators in specific fields of veterinary medicine, who addressed the same research topics from different perspectives in studies based on experimental and spontaneous animal disease models. The study of different pheno-genotypic contexts contributes to the confirmation of translational models of pathologic mechanisms. This review provides an overview of EMT and MET processes in both human and canine species. While human medicine rapidly advances, having a large amount of information available, veterinary medicine is not at the same level. This situation should provide motivation for the veterinary medicine research field, to apply the knowledge on humans to research in pets. By merging the knowledge of these two disciplines, better and faster results can be achieved, thus improving human and canine health.

Beyond SMARCB1 Loss: Recent Insights into the Pathobiology of Epithelioid Sarcoma

Epithelioid sarcoma (ES) is a very rare and aggressive mesenchymal tumor of unclear origin and uncertain lineage characterized by a prevalent epithelioid morphology. The only recurrent genetic alteration reported in ES as yet is the functional inactivation of SMARCB1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1), a key component of the SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling complexes. How SMARCB1 deficiency dictates the clinicopathological characteristics of ES and what other molecular defects concur to its malignant progression is still poorly understood. This review summarizes the recent findings about ES pathobiology, including defects in chromatin remodeling and other signaling pathways and their role as therapeutic vulnerabilities.

Selective Inhibitor of the c-Met Receptor Tyrosine Kinase in Advanced Hepatocellular Carcinoma: No Beneficial Effect With the Use of Tivantinib?

Advanced hepatocellular carcinoma (HCC) remains a formidable health challenge worldwide, with a 5-year survival rate of 2.4% in patients with distant metastases. The hepatocyte growth factor/cellular-mesenchymal-epithelial transition (HGF/c-Met) signaling pathway represents an encouraging therapeutic target for progressive HCC. Tivantinib, a non-adenosine triphosphate-competitive c-Met inhibitor, showed an attractive therapeutic effect on advanced HCC patients with high MET-expression in phase 2 study but failed to meet its primary endpoint of prolonging the overall survival (OS) in two phase 3 HCC clinical trials. Seven clinical trials have been registered in the "ClinicalTrials.gov" for investigating the safety and efficacy of tivantinib in treating advanced or unresectable HCC. Eight relevant studies have been published with results. The sample size ranged from 20 to 340 patients. The methods of tivantinib administration and dosage were orally 120/240/360 mg twice daily. MET overexpression was recorded at 34.6% to 100%. Two large sample phase 3 studies (the METIV-HCC study of Australia and European population and the JET-HCC study of the Japanese population) revealed that tivantinib failed to show survival benefits in advanced HCC. Common adverse events with tivantinib treatment include neutropenia, ascites, rash, and anemia, etc. Several factors may contribute to the inconsistency between the phase 2 and phase 3 studies of tivantinib, including the sample size, drug dosing, study design, and the rate of MET-High. In the future, high selective MET inhibitors combined with a biomarker-driven patient selection may provide a potentially viable therapeutic strategy for patients with advanced HCC.

Rapamycin enhances the anti-tumor activity of cabozantinib in cMet inhibitor-resistant hepatocellular carcinoma

Cabozantinib, mainly targeting cMet and vascular endothelial growth factor receptor 2, is the second-line treatment for patients with advanced hepatocellular carcinoma (HCC). However, the lower response rate and resistance limit its enduring clinical benefit. In this study, we found that cMet-low HCC cells showed primary resistance to cMet inhibitors, and the combination of cabozantinib and mammalian target of rapamycin (mTOR) inhibitor, rapamycin, exhibited a synergistic inhibitory effect on the in vitro cell proliferation and in vivo tumor growth of these cells. Mechanically, the combination of rapamycin with cabozantinib resulted in the remarkable inhibition of AKT, extracellular signal-regulated protein kinases, mTOR, and common downstream signal molecules of receptor tyrosine kinases; decreased cyclin D1 expression; and induced cell cycle arrest. Meanwhile, rapamycin enhanced the inhibitory effects of cabozantinib on the migration and tubule formation of human umbilical vascular endothelial cells and human growth factor-induced invasion of cMet inhibitor-resistant HCC cells under hypoxia condition. These effects were further validated in xenograft models. In conclusion, our findings uncover a potential combination therapy of cabozantinib and rapamycin to combat cabozantinib-resistant HCC.

CHIR99021, trough GSK-3β Targeting, Reduces Epithelioid Sarcoma Cell Proliferation by Activating Mitotic Catastrophe and Autophagy

Epithelioid sarcoma (ES) is a rare disease representing <1% of soft tissue sarcomas. Current therapies are based on anthracycline alone or in combination with ifosfamide or other cytotoxic drugs. ES is still characterized by a poor prognosis with high rates of recurrence. Indeed, for years, ES survival rates have remained stagnant, suggesting that conventional treatments should be revised and improved. New therapeutic approaches are focused to target the key regulators of signaling pathways, the causative markers of tumor pathophysiology. To this end, we selected, among the drugs to which an ES cell line is highly sensitive, those that target signaling pathways known to be dysregulated in ES. In particular, we found a key role for GSK-3β, which results in up-regulation in tumor versus normal tissue samples and associated to poor prognosis in sarcoma patients. Following this evidence, we evaluated CHIR99021, a GSK-3 inhibitor, as a potential drug for use in ES therapy. Our data highlight that, in ES cells, CHIR99021 induces cell cycle arrest, mitotic catastrophe (MC) and autophagic response, resulting in reduced cell proliferation. Our results support the potential efficacy of CHIR99021 in ES treatment and encourage further preclinical and clinical studies.

New FDA oncology small molecule drugs approvals in 2020: Mechanism of action and clinical applications

In 2020, fifty-three new drugs, including forty small-molecules (thirty-six new chemical entities and four new diagnostic agents) and thirteen biologic drugs were approved by the U.S. Food and Drug Administration (FDA). This year, small-molecules continue to play a role in innovative treatments representing around 75% of all drugs accepted by FDA. The dominant therapeutic area was oncology, accounting for twenty-three new approvals, including thirteen new chemical entities, four new diagnostic agents, and thirteen biologic drugs. Recognizing the importance of small-molecules on cancer treatment, this review aims to provide an overview regarding the clinical applications and mechanism of action of the thirteen new small-molecules (excluding new diagnostic agents) approved by FDA in 2020.

Epithelioid Sarcoma-From Genetics to Clinical Practice

Epithelioid sarcoma is a mesenchymal soft tissue sarcoma often arising in the extremities, usually in young adults with a pick of incidence at 35 years of age. Epithelioid sarcoma (ES) is characterized by the loss of SMARCB1/INI1 (integrase interactor 1) or other proteins of the SWI/SNF complex. Two distinct types, proximal and distal, with varying biology and treatment outcomes, are distinguished. ES is known for aggressive behavior, including a high recurrence rate and regional lymph node metastases. An optimal long-term management strategy is still to be defined. The best treatment of localized ES is wide surgical resection. Neo-adjuvant or adjuvant radiotherapy may be recommended, as it reduces the local recurrence rate. Sentinel lymph node biopsy should be considered in ES patients. Patients with metastatic ES have a poor prognosis with an expected median overall survival of about a year. Doxorubicin-based regimens are recommended for advanced ES. Tazemetostat, an EZH2 methyltransferase, has shown promising results in ES patients. Novel therapies, including immunotherapy, are still needed.

Epithelioid sarcoma of the scalp: a case report and literature review

Epithelioid sarcoma (ES) is an aggressive mesenchymal tumor exhibiting bi-directional phenotypes. According to its proclivity for different sites, ES can be subdivided into two categories: distal and proximal variants. Proximal ES often affects the truncal tissue, thighs, head, and neck. Accumulating evidence indicates that several locations in the head, including the orbital, gingival, and nasal cavities, are involved in ES. However, the underlying mechanisms of ES carcinogenesis and progression are largely unknown, including and especially the reason why the tumor cells are positive for both epithelial and mesenchymal classical markers. Thus, we wish to share a rare case of ES in the scalp and its clinical and molecular features. Only 9 cases to date have been reported. An 80-years-old man had sustained a painful swollen mass in his scalp for three months. A diagnosis of epithelioid sarcoma was established based on the combination of the histopathological and immunohistochemical findings. The tumor cells were positive for both mesenchymal (vimentin and S100) and epithelial markers (pan-cytokeratin). This case suggests that ES can be derived from the soft tissue of the scalp. The tumor cells co-expressed biomarkers of epithelial and mesenchymal cells, suggesting the mesenchymal-epithelial transition (MET) may be involved.

PKI-587 enhances chemosensitivity of oxaliplatin in hepatocellular carcinoma through suppressing DNA damage repair pathway (NHEJ and HR) and PI3K/AKT/mTOR pathway

Oxaliplatin resistance limits its effectiveness in the treatment of hepatocellular carcinoma (HCC). Abnormal activation of the PI3K/AKT/mTOR pathway has been associated with decreased survival of HCC patients, anti-apoptosis after chemotherapeutic drug-induced DNA damage, and chemoresistance. In this research, we evaluated the effect of the dual PI3K/mTOR inhibitor, PKI-587, on the sensitivity of oxaliplatin in HCC. Two HCC cell lines (HepG2 and SK-Hep1) were used to analyze PKI-587 for DNA damage response, cell proliferation, clonogenic survival, cell cycle and apoptosis after oxaliplatin treatment. A HepG2 tumor-bearing model was used to assess the in vivo effects of the combination of the two compounds. In HCC cells, oxaliplatin stably activated the PI3K/AKT/mTOR pathway, including up-regulation of p-Akt (Ser473), p-mTOR (Ser2448), p-mTOR (Ser2481), p-elF4EBP1, and p-S6K1, and activated the DNA damage repair pathways (non-homologous end joining (NHEJ) and homologous recombination (HR)), up-regulation of p-DNAPKcs (Ser2056), p-ATM (Ser1981), and p-ATR (Ser428), which were attenuated by PKI-587. Compared with oxaliplatin alone, the combination of PKI-587 and oxaliplatin increased the number of γ-H2AX/cells, decreased proliferation of cells, and an increased the percentage of G0/G1 phase cells and apoptotic cells. In vivo, the combination of oxaliplatin with PKI-587 inhibited tumor growth. Anti-tumor effects were associated with induction of mitochondrial apoptosis and inhibition of phosphorylation of mTOR, Akt and γ-H2AX. We conclude that PKI-587 enhances chemosensitivity of oxaliplatin in HCC through suppressing the PI3K/AKT/mTOR signalling pathway and inhibiting the DNA damage repair pathway. The combination of PKI-587 and oxaliplatin appears to be a promising regimen for the treatment of HCC.

The PTEN Tumor Suppressor Gene in Soft Tissue Sarcoma

Soft tissue sarcoma (STS) is a rare malignancy of mesenchymal origin classified into more than 50 different subtypes with distinct clinical and pathologic features. Despite the poor prognosis in the majority of patients, only modest improvements in treatment strategies have been achieved, largely due to the rarity and heterogeneity of these tumors. Therefore, the discovery of new prognostic and predictive biomarkers, together with new therapeutic targets, is of enormous interest. Phosphatase and tensin homolog (PTEN) is a well-known tumor suppressor that commonly loses its function via mutation, deletion, transcriptional silencing, or protein instability, and is frequently downregulated in distinct sarcoma subtypes. The loss of PTEN function has consequent alterations in important pathways implicated in cell proliferation, survival, migration, and genomic stability. PTEN can also interact with other tumor suppressors and oncogenic signaling pathways that have important implications for the pathogenesis in certain STSs. The aim of the present review is to summarize the biological significance of PTEN in STS and its potential role in the development of new therapeutic strategies.

Inhibition of HGF/MET signaling decreases overall tumor burden and blocks malignant conversion in Tpl2-related skin cancer

Tumor progression locus 2 (Tpl2) is a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family of serine/threonine kinases. Deletion of the Tpl2 gene is associated with a significantly higher number of papillomas and cutaneous squamous cell carcinomas (cSCCs). Overexpression of hepatocyte growth factor (HGF) and its receptor MET is abundant in cSCC and can lead to increased proliferation, migration, invasion or resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. The aim of this study was to address whether the increased tumor burden in Tpl2^−/− mice is due to aberrant HGF/MET signaling. C57Bl/6 wild type (WT) and Tpl2^−/− mice were subjected to a two-stage chemical carcinogenesis protocol for one year. At the time of promotion half of the mice received 44 mg/kg capmatinib (INC 280), a pharmacological inihibitor of MET, in their diet. Tpl2^−/− mice had signficantly higher tumor incidence and overall tumor burden compared to WT mice. Further, carcinogen-intiated Tpl2^−/− mice could bypass the need for promotion, as 89% of Tpl2^−/− mice given only DMBA developed papillomas. v-ras^Ha -transduced keratinocytes and SCCs from Tpl2^−/− mice revealed an upregulation in HGF and p-MET signaling compared to WT animals. Long-term capmatinib treatment had no adverse effects in mice and capmatinib-fed Tpl2^−/− mice had a 60% reduction in overall tumor burden. Further, no tumors from Tpl2^−/− mice fed capmatinib underwent malignant conversion. In summary targeting MET may be a potential new strategy to combat cutaneous squamous cell carcinomas that result from dysregulation in MAPK signaling.

The Role of PI3K in Met Driven Cancer: A Recap

The Receptor Tyrosine Kinase (RTK) Met, overexpressed or mutated in cancer, plays a major role in cancer progression and represents an attractive target for cancer therapy. However RTK inhibitors can lead to drug resistance, explaining the necessity to develop therapies that target downstream signaling. Phosphatidylinositide 3-kinase (PI3K) is one of the most deregulated pathways in cancer and implicated in various types of cancer. PI3K signaling is also a major signaling pathway downstream of RTK, including Met. PI3K major effectors include Akt and "mechanistic Target of Rapamycin" (mTOR), which each play key roles in numerous and various cell functions. Advancements made due to the development of molecular and pharmaceutical tools now allow us to delve into the roles of each independently. In this review, we summarize the current understanding we possess of the activation and role of PI3K/Akt/mTOR, downstream of Met, in cancer.

HDAC Inhibition Counteracts Metastatic Re-Activation of Prostate Cancer Cells Induced by Chronic mTOR Suppression

This study was designed to investigate whether epigenetic modulation by histone deacetylase (HDAC) inhibition might circumvent resistance towards the mechanistic target of rapamycin (mTOR) inhibitor temsirolimus in a prostate cancer cell model. Parental (par) and temsirolimus-resistant (res) PC3 prostate cancer cells were exposed to the HDAC inhibitor valproic acid (VPA), and tumor cell adhesion, chemotaxis, migration, and invasion were evaluated. Temsirolimus resistance was characterized by reduced binding of PC3^res cells to endothelium, immobilized collagen, and fibronectin, but increased adhesion to laminin, as compared to the parental cells. Chemotaxis, migration, and invasion of PC3^res cells were enhanced following temsirolimus re-treatment. Integrin α and β receptors were significantly altered in PC3^res compared to PC3^par cells. VPA significantly counteracted temsirolimus resistance by down-regulating tumor cell–matrix interaction, chemotaxis, and migration. Evaluation of integrin expression in the presence of VPA revealed a significant down-regulation of integrin α5 in PC3^res cells. Blocking studies demonstrated a close association between α5 expression on PC3^res and chemotaxis. In this in vitro model, temsirolimus resistance drove prostate cancer cells to become highly motile, while HDAC inhibition reversed the metastatic activity. The VPA-induced inhibition of metastatic activity was accompanied by a lowered integrin α5 surface level on the tumor cells.

Long period of relative quiescence in distal-type epithelioid sarcoma of the forearm with recurrence after surgery: A case report

BACKGROUND

Epithelioid sarcoma (ES) is a rare malignant mesenchymal tumor that only accounts for 0.6% to 1.0% of all cases of sarcomas. ES with a relative quiescent state of more than 10 years is extremely rare.Here, we present a rare case of ES in the forearm of a 17-year-old girl. The patient had a congenital mass in her forearm that measured approximately 1cm; it grew rapidly starting 5 years ago. The mass was not treated until last year when she underwent the first surgery. The mass was located in the middle and lower part of the left forearm and involved the dorsal muscle group, intermuscular space, and subcutaneous tissues without clear boundaries.The patient underwent surgery, and the tumor recurred twice within 1 year postoperatively.

METHODS

The tumor samples were examined via hematoxylin-eosin (HE) and immunohistochemistry staining.

RESULTS

Histopathologically, the tumor comprised large polygonal epithelioid cells with abundant eosinophilic cytoplasm arranged in cell nests. Central necrosis and focal myxoid change could be seen in the tumor tissues. Immunostaining showed that the tumor cells were positive for CD34, CK, EMA, and vimentin but negative for CD31, S-100, and INI-1.

CONCLUSION

Based on these findings, the tumor was diagnosed as ES of distal form. Distal-type ES could have a long period of relative quiescence, after which it could grow rapidly and relapse multiple times over a short duration.

Therapeutic potential of TAS-115 via c-MET and PDGFRα signal inhibition for synovial sarcoma

Background

The prognosis of synovial sarcoma (SS), an aggressive soft tissue sarcoma, remains poor. We previously reported that c-MET or platelet-derived growth factor receptor α (PDGFRα) signalling pathway is related to SS progression based upon the findings of phospho-receptor tyrosine kinase (RTK) arrays. TAS-115 is a novel c-MET/ vascular endothelial growth factor receptor-targeting tyrosine kinase inhibitor that has been shown to inhibit multiple RTKs. Here we aimed to investigate the therapeutic potential of TAS-115 against SS.

Methods

We first evaluated which signalling pathway was relevant to the viability of three human SS cell lines: Yamato-SS, SYO-1 and HS-SY-II. Next, we assessed the anticancer activity and mechanism of action of TAS-115 in these SS cell lines. Finally, we compared the ability of TAS-115 to inhibit c-MET and PDGFRα phosphorylation with that of pazopanib.

Results

We classified the SS cell lines as c-MET-dependent or PDGFRα-dependent based upon the differences in the signalling pathway relevant for growth and/or survival. We also found that c-MET and PDGFRα were the primary activators of both phosphatidylinositol 3-kinase/AKT and mitogen-activated protein kinase pathways in c-MET-dependent and PDGFRα-dependent SS cells, respectively. TAS-115 treatment blocked the phosphorylation of PDGFRα as well as that of c-MET and their downstream effectors, leading to marked growth inhibition in both types of SS cell lines in in vitro and in vivo studies. Furthermore, PDGFRα phosphorylation, on at least four representative autophosphorylation sites, was impeded by TAS-115 equivalently to pazopanib.

Conclusions

These experimental results have demonstrated the significance of c-MET and PDGFRα signalling for growth and/or survival of SS tumours. TAS-115 monotherapy may benefit SS patients whose tumours are dependent upon either c-MET or PDGFRα signalling by functioning as a multiple tyrosine kinase inhibitor to suppress c-MET as well as PDGFRα pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3324-3) contains supplementary material, which is available to authorized users.

Oxygen ultra-fine bubbles water administration prevents bone loss of glucocorticoid-induced osteoporosis in mice by suppressing osteoclast differentiation

Oxygen ultra-fine bubbles (OUB) saline injection prevents bone loss of glucocorti\coid-induced osteoporosis in mice, and OUB inhibit osteoclastogenesis via RANK-TRAF6-c-Fos-NFATc1 signaling and RANK-p38 MAPK signaling in vitro.

INTRODUCTION

Ultra-fine bubbles (<200 nm in diameter) have several unique properties, and they are tested in various medical fields. The purpose of this study was to investigate the effects of oxygen ultra-fine bubbles (OUB) on glucocorticoid-induced osteoporosis (GIO) model mice.

METHODS

Prednisolone (PSL, 5 mg) was subcutaneously inserted in 6-month-old male C57BL/6J mice, and 200 μl of saline, OUB-diluted saline, or nitrogen ultra-fine bubbles (NUB)-diluted saline was intraperitoneally injected three times per week for 8 weeks the day after operations. Mice were divided into four groups; (1) control, sham-operation + saline; (2) GIO, PSL + saline; (3) GIO + OUB, PSL + OUB saline; (4) GIO + NUB, PSL + NUB saline. The effects of OUB on osteoblasts and osteoclasts were examined by serially diluted OUB medium in vitro.

RESULTS

Bone mass was significantly decreased in GIO [bone volume/total volume (%): control vs. GIO 12.6 vs. 7.9; p < 0.01] while significantly preserved in GIO + OUB (GIO vs. GIO + OUB 7.9 vs. 12.9; p < 0.05). In addition, tartrate-resistant acid phosphatase (TRAP)-positive cells in the distal femur [mean osteoclasts number/bone surface (mm^-1)] was significantly increased in GIO (control vs. GIO 6.8 vs. 11.6; p < 0.01) while suppressed in GIO + OUB (GIO vs. GIO + OUB 11.6 vs. 7.5; p < 0.01). NUB did not affect these parameters. In vitro experiments revealed that OUB significantly inhibited osteoclastogenesis by inhibiting RANK-TRAF6-c-Fos-NFATc1 signaling, RANK-p38 MAPK signaling, and TRAP/Cathepsin K/DC-STAMP mRNA expression in a concentration-dependent manner. OUB did not affect osteoblastogenesis in vitro.

CONCLUSIONS

OUB prevent bone loss in GIO mice by inhibiting osteoclastogenesis.

Functional and therapeutic relevance of hepatocyte growth factor/c-MET signaling in synovial sarcoma

Synovial sarcoma (SS) is an aggressive soft tissue sarcoma with a poor prognosis and, thus, novel therapeutic strategies for SS are urgently required. In the present study, we investigated the functional and therapeutic relevance of hepatocyte growth factor (HGF)/c‐MET signaling in SS. Both HGF and c‐MET were highly expressed in Yamato‐SS cells, resulting in activation of c‐MET and its downstream AKT and extracellular signal‐regulated kinase signaling pathways, whereas c‐MET was expressed but not activated in SYO‐1 or HS‐SY‐II cells. c‐MET‐activated Yamato‐SS cells showed higher anchorage‐independent growth ability and less sensitivity to chemotherapeutic agents than did c‐MET‐inactivated SYO‐1 or HS‐SY‐II cells. INC280, a selective c‐MET inhibitor, inhibited growth of Yamato‐SS cells both in vitro and in vivo but not that of SYO‐1 or HS‐SY‐II cells. INC280 induced cell cycle arrest and apoptosis, and blocked phosphorylation of c‐MET and its downstream effectors in Yamato‐SS cells. Co‐expression of HGF and c‐MET in SS clinical samples correlated with a poor prognosis in patients with SS. Taken together, activation of HGF/c‐MET signaling in an autocrine fashion leads to an aggressive phenotype in SS and targeting of this signaling exerts superior antitumor effects on c‐MET‐activated SS. HGF/c‐MET expression status is a potential biomarker for identification of SS patients with a worse prognosis who can benefit from c‐MET inhibitors.

A case study of an integrative genomic and experimental therapeutic approach for rare tumors: identification of vulnerabilities in a pediatric poorly differentiated carcinoma

Background

Precision medicine approaches are ideally suited for rare tumors where comprehensive characterization may have diagnostic, prognostic, and therapeutic value. We describe the clinical case and molecular characterization of an adolescent with metastatic poorly differentiated carcinoma (PDC). Given the rarity and poor prognosis associated with PDC in children, we utilized genomic analysis and preclinical models to validate oncogenic drivers and identify molecular vulnerabilities.

Methods

We utilized whole exome sequencing (WES) and transcriptome analysis to identify germline and somatic alterations in the patient’s tumor. In silico and in vitro studies were used to determine the functional consequences of genomic alterations. Primary tumor was used to generate a patient-derived xenograft (PDX) model, which was used for in vivo assessment of predicted therapeutic options.

Results

WES revealed a novel germline frameshift variant (p.E1554fs) in APC, establishing a diagnosis of Gardner syndrome, along with a somatic nonsense (p.R790*) APC mutation in the tumor. Somatic mutations in TP53, MAX, BRAF, ROS1, and RPTOR were also identified and transcriptome and immunohistochemical analyses suggested hyperactivation of the Wnt/ß-catenin and AKT/mTOR pathways. In silico and biochemical assays demonstrated that the MAX p.R60Q and BRAF p.K483E mutations were activating mutations, whereas the ROS1 and RPTOR mutations were of lower utility for therapeutic targeting. Utilizing a patient-specific PDX model, we demonstrated in vivo activity of mTOR inhibition with temsirolimus and partial response to inhibition of MEK.

Conclusions

This clinical case illustrates the depth of investigation necessary to fully characterize the functional significance of the breadth of alterations identified through genomic analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-016-0366-0) contains supplementary material, which is available to authorized users.

Management of Epithelioid Sarcoma of the Inguinal Region with Vascular Invasion

Epithelioid sarcoma (ES) is a rare clinically polymorphic tumor that mimics both benign and malignant conditions. It presents with dermal or subcutaneous nodules on the extremities in young adults. We present here a case of epithelioid sarcoma of the inguinal region infiltrating the femoral vessels. Biopsy is diagnostic and good histopathological evaluation is critical in management.

Sorafenib and DE605, a novel c-Met inhibitor, synergistically suppress hepatocellular carcinoma

Sorafenib, an oral multikinase inhibitor of Raf, VEGF and PDGF receptor signaling is approved for advanced hepatocellular carcinoma (HCC). One strategy to improve HCC therapy is to combine agents that target key signaling pathways. Aberrant mesenchymal-epithelial transition factor (c-Met) activation is associated with a variety of human malignancies and therefore represents a target for therapy. In this study, we investigated a novel c-Met inhibitor, DE605, together with sorafenib in hepatocellular carcinoma cells in vitro and in vivo. DE605 and sorafenib synergistically induced apoptosis in hepatocellular carcinoma cells. Mechanistically, DE605 activated the FGFR3/Erk pathway, which in turn was inhibited by sorafenib, resulting in synergism. Finally, DE605 and sorafenib significantly inhibited growth of PLC/PRF/5 hepatocellular carcinoma tumor xenografts in athymic nude mice. Importantly, no obvious weight loss (toxicity) was detected. Thus in combination, DE605 and sorafenib target complementary anti-apoptotic pathways and synergistically suppress HCC, providing the rationale for clinical studies with this novel combination.

Cabozantinib and Tivantinib, but Not INC280, Induce Antiproliferative and Antimigratory Effects in Human Neuroendocrine Tumor Cells in vitro: Evidence for 'Off-Target' Effects Not Mediated by c-Met Inhibition

BACKGROUND/AIMS

The hepatocyte growth factor/transmembrane tyrosine kinase receptor c-Met has been defined as a potential target in antitumoral treatment of various carcinomas. We aimed to investigate the direct effect of c-Met inhibition on neuroendocrine tumor cells in vitro.

METHODS

The effects of the multi-tyrosine kinase inhibitors cabozantinib and tivantinib and of the highly specific c-Met inhibitor INC280 were investigated in human pancreatic neuroendocrine BON1, bronchopulmonary NCI-H727 and midgut GOT1 cells in vitro.

RESULTS

INC280, cabozantinib and tivantinib inhibited c-Met phosphorylation, respectively. However, while equimolar concentrations (10 μM) of cabozantinib and tivantinib inhibited cell viability and cell migration, INC280 had no inhibitory effect. Knockdown experiments with c-Met siRNA also did not demonstrate effects on cell viability. Cabozantinib and tivantinib caused a G2 arrest in neuroendocrine tumor cells.

CONCLUSIONS

Our in vitro data suggest that c-Met inhibition alone is not sufficient to exert direct antitumoral or antimigratory effects in neuroendocrine tumor cells. The multi-tyrosine kinase inhibitors cabozantinib and tivantinib show promising antitumoral and antimigratory effects in neuroendocrine tumor cells, which are most probably 'off-target' effects, not mediated by c-Met.

The genomic landscape of epithelioid sarcoma cell lines and tumours

We carried out whole genome and transcriptome sequencing on four tumour/normal pairs of epithelioid sarcoma. These index cases were supplemented with whole transcriptome sequencing of three additional tumours and three cell lines. Unlike rhabdoid tumour (the other major group of SMARCB1-negative cancers), epithelioid sarcoma shows a complex genome with a higher mutational rate, comparable to that of ovarian carcinoma. Despite this mutational burden, SMARCB1 mutations remain the most frequently recurring event and are probably critical drivers of tumour formation. Several cases show heterozygous SMARCB1 mutations without inactivation of the second allele, and we explore this further in vitro. Finding CDKN2A deletions in our discovery cohort, we evaluated CDKN2A protein expression in a tissue microarray. Six out of 16 cases had lost CDKN2A in greater than or equal to 90% of cells, while the remaining cases had retained the protein. Expression analysis of epithelioid sarcoma cell lines by transcriptome sequencing shows a unique profile that does not cluster with any particular tissue type or with other SWI/SNF-aberrant lines. Evaluation of the levels of members of the SWI/SNF complex other than SMARCB1 revealed that these proteins are expressed as part of a residual complex, similarly to previously studied rhabdoid tumour lines. This residual SWI/SNF is susceptible to synthetic lethality and may therefore indicate a therapeutic opportunity.

Progranulin plays crucial roles in preserving bone mass by inhibiting TNF-α-induced osteoclastogenesis and promoting osteoblastic differentiation in mice

A close correlation between atherosclerosis, inflammation, and osteoporosis has been recognized, although the precise mechanism remains unclear. The growth factor progranulin (PGRN) is expressed in various cells such as macrophages, leukocytes, and chondrocytes. PGRN plays critical roles in a variety of diseases, such as atherosclerosis and arthritis by inhibiting Tumor Necrosis Factor-α (TNF-α) signaling. The purpose of this study was to investigate the effect of PGRN on bone metabolism. Forty-eight-week old female homozygous PGRN knockout mice (PGRN-KO) (n = 8) demonstrated severe low bone mass in the distal femur compared to age- and sex-matched wild type C57BL/6J mice (WT) (n = 8) [BV/TV (%): 5.8 vs. 16.6; p < 0.001, trabecular number (1/mm): 1.6 vs. 3.8; p < 0.001]. In vitro, PGRN inhibited TNF-α-induced osteoclastogenesis from spleen cells of PGRN-KO mice. Moreover, PGRN significantly promoted ALP activity, osteoblast-related mRNA (ALP, osteocalcin) expression in a dose-dependent manner and up-regulated osteoblastic differentiation by down-regulating phosphorylation of ERK1/2 in mouse calvarial cells. In conclusion, PGRN may be a promising treatment target for both atherosclerosis and inflammation-related osteoporosis.

Epithelioid Sarcoma: Opportunities for Biology-Driven Targeted Therapy

Epithelioid sarcoma (ES) is a soft tissue sarcoma of children and young adults for which the preferred treatment for localized disease is wide surgical resection. Medical management is to a great extent undefined, and therefore for patients with regional and distal metastases, the development of targeted therapies is greatly desired. In this review, we will summarize clinically relevant biomarkers (e.g., SMARCB1, CA125, dysadherin, and others) with respect to targeted therapeutic opportunities. We will also examine the role of EGFR, mTOR, and polykinase inhibitors (e.g., sunitinib) in the management of local and disseminated disease. Toward building a consortium of pharmaceutical, academic, and non-profit collaborators, we will discuss the state of resources for investigating ES with respect to cell line resources, tissue banks, and registries so that a roadmap can be developed toward effective biology-driven therapies.