The clinical relevance of molecular genetics in soft tissue sarcomas

A Different Way to Think About Syndromes of Hereditary Colorectal Cancer

BACKGROUND

Hereditary colorectal cancer is an increasingly complex field in which the commoner syndromes are being augmented by rarer genetic presentations contributing to familial polyposis and colorectal cancer. Coming to grips with the complexity is difficult because of the phenotypic and genotypic overlap between syndromes.

OBJECTIVE

This study aimed to describe a new way of thinking about syndromes of hereditary colorectal cancer based on their embryonic tissue of origin.

DATA SOURCES

Articles were searched through PubMed and MEDLINE.

STUDY SELECTION

The terms "hereditary colorectal cancer," "syndromes of hereditary colorectal cancer," and "hereditary polyposis" were used to direct the search.

RESULTS

Primarily endoderm-derived syndromes were different from mesoderm-derived syndromes in their genetics, molecular biology, histology, and clinical course.

LIMITATIONS

There is considerable phenotypic and genotypic overlap between syndromes, even when considering embryonic tissue of origin.

CONCLUSIONS

Thinking about hereditary syndromes of colorectal cancer from the perspective of embryonic tissue of origin provides a fresh look at phenotype and genotype that opens new areas of exploration.

UNA FORMA DIFERENTE DE PENSAR SOBRE LOS SNDROMES DEL CNCER COLORRECTAL HEREDITARIO

ANTECEDENTES:El cáncer colorrectal hereditario es un campo cada vez más complejo donde los síndromes más comunes se ven aumentados por presentaciones genéticas más raras que contribuyen a la poliposis familiar y al cáncer colorrectal. Hacer frente a esta complejidad resulta difícil debido a la superposición fenotípica y genotípica entre los síndromes.OBJETIVO:En este artículo, describimos una nueva forma de pensar sobre los síndromes de cáncer colorrectal hereditario en función del origen de su tejido embrionario.FUENTES DE DATOS:Se realizaron búsquedas de artículos en Pubmed y Medline.SELECCIÓN DE ESTUDIOS:Se utilizaron los términos "cáncer colorrectal hereditario", "síndromes de cáncer colorrectal hereditario", "poliposis hereditaria" para dirigir la búsqueda.RESULTADOS:Principalmente los síndromes derivados del endodermo fueron diferentes a los síndromes derivados del mesodermo en su genética, biología molecular, histología y curso clínico.LIMITACIONES:Existe una superposición fenotípica y genotípica considerable entre los síndromes, incluso cuando se considera el tejido de origen embrionario.CONCLUSIÓN:Pensar en los síndromes hereditarios del cáncer colorrectal desde la perspectiva del tejido embrionario de origen proporciona una nueva mirada al fenotipo y al genotipo que abre nuevas áreas de exploración. (Traducción-Dr Osvaldo Gauto ).

Does PAX7 and NKX2.2 immunoreactivity in Ewing sarcoma have prognostic significance?

Ewing sarcoma (ES) is an aggressive neoplasm with variable morphology. It has no specific immunoprofile or molecular signature. Neither CD99, NKX2.2 nor PAX7 immunoreactivity alone is completely specific, although diagnostic specificity improves when combined. The purpose of the present study was to investigate the immunohistochemical (IHC) expression of PAX7 in a large series of genetically confirmed ES. Existing results for CD99 and NKX2.2 immunoexpression, morphological findings and molecular studies (fusion gene subtypes) were retrieved from a previous study. Survival analyses were performed in cases with available clinical follow-up. PAX7 was positive in 95.5% of ES with diffuse staining (> 50%) in all positive cases and moderate or strong intensity for most cases. Nineteen ES displayed both PAX7 and CD99 immunoreactivity but lacked NKX2.2 immunoexpression. No relationships could be found between PAX7 expression and the histological types or ES gene fusion subtypes. Univariant/multivariate analysis showed that lack of PAX7 and/or NKX2.2 immunoexpression constitute independent poor prognostic factors for progression free survival (PFS) and overall survival (OS). In conclusion, IHC for CD99, NKX2.2, and PAX7 may be useful in daily practice for ES diagnosis, particularly in hospitals lacking facilities for molecular studies. In addition, the combination of strong CD99 membranous positivity and nuclear PAX7 and NKX2.2 immunoreactivity seems to be very reliable for ES diagnosis when supported by a corroborating histomorphologic and clinical picture. Although PAX7 is not entirely specific for ES, it seems to have a more extensive and strong nuclear immunoreactivity than NKX2.2 expression, even in tumors with decalcification artifact. Considering the prognostically significant data herein reported, we strongly recommend validation in prospective ES series that include localized and disseminated tumors.

Molecular Pathology of Soft-Tissue Neoplasms and Its Role in Clinical Practice

BACKGROUND

Soft-tissue neoplasms embody a histologically diverse group of mesenchymal tumors. Oftentimes the histopathological diagnosis of soft-tissue tumors is challenging due to overlapping pathological features.

METHODS

We reviewed the current and most importantly known recurrent or tumor-specific genetic abnormalities involving soft-tissue tumors, focusing on how they are useful in working up differential diagnoses and the relevance of potentially targeted therapies.

RESULTS

Molecular diagnostic tools have shown great advantage as an aid in the differentiation between different soft-tissue tumor entities, providing a potential avenue in the identification of novel therapeutic targets. Gastrointestinal stromal tumor is a well-known example of a soft-tissue tumor with a successful, molecularly driven treatment with response rates of more than 80% in stable disease and partial remission. Classifying soft-tissue neoplasms by their molecular genetic pathology has been considered as molecular testing becomes more integrated into various diagnostic and prognostic algorithms.

CONCLUSIONS

Molecular pathology provides a unique opportunity for pathologists to play a crucial role in the multidisciplinary care of patients with sarcoma. These opportunities include but are not limited to the appropriate triage of tissue for molecular testing and the integration of molecular testing results, with histological and immunohistochemical findings providing actionable information for the diagnosis, prognosis, and choice of therapeutic modality.

The importance of being dead: cell death mechanisms assessment in anti-sarcoma therapy

Cell death can occur through different mechanisms, defined by their nature and physiological implications. Correct assessment of cell death is crucial for cancer therapy success. Sarcomas are a large and diverse group of neoplasias from mesenchymal origin. Among cell death types, apoptosis is by far the most studied in sarcomas. Albeit very promising in other fields, regulated necrosis and other cell death circumstances (as so-called "autophagic cell death" or "mitotic catastrophe") have not been yet properly addressed in sarcomas. Cell death is usually quantified in sarcomas by unspecific assays and in most cases the precise sequence of events remains poorly characterized. In this review, our main objective is to put into context the most recent sarcoma cell death findings in the more general landscape of different cell death modalities.

A small molecule inhibitor of ETV1, YK-4-279, prevents prostate cancer growth and metastasis in a mouse xenograft model

BACKGROUND

The erythroblastosis virus E26 transforming sequences (ETS) family of transcription factors consists of a highly conserved group of genes that play important roles in cellular proliferation, differentiation, migration and invasion. Chromosomal translocations fusing ETS factors to promoters of androgen responsive genes have been found in prostate cancers, including the most clinically aggressive forms. ERG and ETV1 are the most commonly translocated ETS proteins. Over-expression of these proteins in prostate cancer cells results in a more invasive phenotype. Inhibition of ETS activity by small molecule inhibitors may provide a novel method for the treatment of prostate cancer.

METHODS AND FINDINGS

We recently demonstrated that the small molecule YK-4-279 inhibits biological activity of ETV1 in fusion-positive prostate cancer cells leading to decreased motility and invasion in-vitro. Here, we present data from an in-vivo mouse xenograft model. SCID-beige mice were subcutaneously implanted with fusion-positive LNCaP-luc-M6 and fusion-negative PC-3M-luc-C6 tumors. Animals were treated with YK-4-279, and its effects on primary tumor growth and lung metastasis were evaluated. YK-4-279 treatment resulted in decreased growth of the primary tumor only in LNCaP-luc-M6 cohort. When primary tumors were grown to comparable sizes, YK-4-279 inhibited tumor metastasis to the lungs. Expression of ETV1 target genes MMP7, FKBP10 and GLYATL2 were reduced in YK-4-279 treated animals. ETS fusion-negative PC-3M-luc-C6 xenografts were unresponsive to the compound. Furthermore, YK-4-279 is a chiral molecule that exists as a racemic mixture of R and S enantiomers. We established that (S)-YK-4-279 is the active enantiomer in prostate cancer cells.

CONCLUSION

Our results demonstrate that YK-4-279 is a potent inhibitor of ETV1 and inhibits both the primary tumor growth and metastasis of fusion positive prostate cancer xenografts. Therefore, YK-4-279 or similar compounds may be evaluated as a potential therapeutic tool for treatment of human prostate cancer at different stages.

ChildSeq-RNA: A next-generation sequencing-based diagnostic assay to identify known fusion transcripts in childhood sarcomas

Childhood sarcomas can be extremely difficult to accurately diagnose on the basis of morphological characteristics alone. Ancillary methods, such as RT-PCR or fluorescence in situ hybridization, to detect pathognomonic gene fusions can help to distinguish these tumors. Two major deficiencies of these assays are their inability to identify gene fusions at nucleotide resolution or to detect multiple gene fusions simultaneously. We developed a next-generation sequencing-based assay designated ChildSeq-RNA that uses the Ion Torrent platform to screen for EWSR1-FLI1 and EWSR1-ERG, PAX3-FOXO1 and PAX7-FOXO1, EWSR1-WT1, and ETV6-NTRK3 fusions of Ewing sarcoma (ES), alveolar rhabdomyosarcoma, desmoplastic small round cell tumor, and congenital fibrosarcoma, respectively. To rapidly analyze resulting data, we codeveloped a bioinformatics tool, termed ChildDecode, that operates on a scalable, cloud-computing platform. Total RNA from four ES cell lines plus 33 clinical samples representing ES, alveolar rhabdomyosarcoma, desmoplastic small round cell tumor, and congenital fibrosarcoma tumors was subjected to ChildSeq-RNA. This accurately identified corresponding gene fusions in each tumor type, with no examples of false positive fusion detection in this proof-of-concept study. Comparison with previous RT-PCR findings demonstrated high sensitivity (96.4%; 95% CI, 82.3%-99.4%) and specificity (100%; 95% CI, 56.6%-100%) of ChildSeq-RNA to detect gene fusions. Herein, we propose ChildSeq-RNA as a novel tool to detect gene fusions in childhood sarcomas at single-nucleotide resolution.

Characterization of human mesenchymal stem cells from ewing sarcoma patients. Pathogenetic implications

BACKGROUND

Ewing Sarcoma (EWS) is a mesenchymal-derived tumor that generally arises in bone and soft tissue. Intensive research regarding the pathogenesis of EWS has been insufficient to pinpoint the early events of Ewing sarcomagenesis. However, the Mesenchymal Stem Cell (MSC) is currently accepted as the most probable cell of origin.

MATERIALS AND METHODS

In an initial study regarding a deep characterization of MSC obtained specifically from EWS patients (MSC-P), we compared them with MSC derived from healthy donors (MSC-HD) and EWS cell lines. We evaluated the presence of the EWS-FLI1 gene fusion and EWSR1 gene rearrangements in MSC-P. The presence of the EWS transcript was confirmed by q-RT-PCR. In order to determine early events possibly involved in malignant transformation, we used a multiparameter quantitative strategy that included both MSC immunophenotypic negative/positive markers, and EWS intrinsic phenotypical features. Markers CD105, CD90, CD34 and CD45 were confirmed in EWS samples.

RESULTS

We determined that MSC-P lack the most prevalent gene fusion, EWSR1-FLI1 as well as EWSR1 gene rearrangements. Our study also revealed that MSC-P are more alike to MSC-HD than to EWS cells. Nonetheless, we also observed that EWS cells had a few overlapping features with MSC. As a relevant example, also MSC showed CD99 expression, hallmark of EWS diagnosis. However, we observed that, in contrast to EWS cells, MSC were not sensitive to the inhibition of CD99.

CONCLUSIONS

In conclusion, our results suggest that MSC from EWS patients behave like MSC-HD and are phenotypically different from EWS cells, thus raising important questions regarding MSC role in sarcomagenesis.

Xenograft and genetically engineered mouse model systems of osteosarcoma and Ewing's sarcoma: tumor models for cancer drug discovery

INTRODUCTION

There are > 75 histological types of solid tumors that are classified into two major groups: bone and soft-tissue sarcomas. These diseases are more prevalent in children, and pediatric sarcomas tend to be highly aggressive and rapidly progressive. Sarcomas in adults may follow a more indolent course, but aggressive tumors are also common. Sarcomas that are metastatic at diagnosis, or recurrent following therapy, remain refractory to current treatment options with dismal overall survival rates. A major focus of clinical trials, for patients with sarcoma, is to identify novel and more effective therapeutic strategies targeted to genomic or proteomic aberrations specific to the malignant cells. Critical to the understanding of the potential for targeted therapies are models of disease that are representative of clinical disease and predictive of relevant clinical responses.

AREAS COVERED

In this article, the authors discuss the use of mouse xenograft models and genetically engineered mice in cancer drug discovery. The authors provide a special focus on models for the two most common bone sarcomas: osteosarcoma (OS) and Ewing's sarcoma (ES).

EXPERT OPINION

Predicting whether a new anticancer agent will have a positive therapeutic index in patients with OS and ES remains a challenge. The use of mouse sarcoma models for understanding the mechanisms involved in the response of tumors to new treatments is an important step in the process of drug discovery and the development of clinically relevant therapeutic strategies for these diseases.

Caveolin-1 in sarcomas: friend or foe?

Sarcomas represent a heterogeneous group of tumors with a complex and difficult reproducible classification. Their pathogenesis is poorly understood and there are few effective treatment options for advanced disease. Caveolin-1 is a multifunctional scaffolding protein with multiple binding partners that regulates multiple cancer-associated processes including cellular transformation, tumor growth, cell death and survival, multidrug resistance, angiogenesis, cell migration and metastasis. However, ambiguous roles have been ascribed to caveolin-1 in signal transduction and cancer, including sarcomas. In particular, evidence indicating that caveolin-1 function is cell context dependent has been repeatedly reported. Caveolin-1 appears to act as a tumor suppressor protein at early stages of cancer progression. In contrast, a growing body of evidence indicates that caveolin-1 is up-regulated in several multidrug-resistant and metastatic cancer cell lines and human tumor specimens. This review is focused on the role of caveolin-1 in several soft tissue and bone sarcomas and discusses the use of this protein as a potential diagnostic and prognostic marker and as a therapeutic target.

Molecular Diagnostics of Soft Tissue Tumors

Context.—Soft tissue pathology encompasses a remarkably diverse assortment of benign and malignant soft tissue tumors. Rendering a definitive diagnosis is complicated not only by the large volume of existing histologic subtypes (>100) but also frequently by the presence of overlapping clinical, histologic, immunohistochemical, and/or radiographic features. During the past 3 decades, mesenchymal tumor–specific, cytogenetic and molecular genetic abnormalities have demonstrated an increasingly important, ancillary role in mesenchymal tumor diagnostics.

Objectives.—To review molecular diagnostic tools available to the pathologist to further classify specific soft tissue tumor types and recurrent aberrations frequently examined. Advantages and limitations of individual approaches will also be highlighted.

Data Sources.—Previously published review articles, peer-reviewed research publications, and the extensive cytogenetic and molecular diagnostic experience of the authors to include case files of The University of Nebraska Medical Center.

Conclusions.—Cytogenetic and molecular genetic assays are used routinely for diagnostic purposes in soft tissue pathology and represent a powerful adjunct to complement conventional microscopy and clinicoradiographic evaluation in the formulation of an accurate diagnosis. Care should be taken, however, to recognize the limitations of these approaches. Ideally, more than one technical approach should be available to a diagnostic laboratory to compensate for the shortcomings of each approach in the assessment of individual specimens.

The role of chemokine receptor CXCR4 in the biologic behavior of human soft tissue sarcoma

The molecular basis of sarcoma remains poorly understood. However, recent studies have begun to uncover some of the molecular pathways involved in sarcomagenesis. The chemokine receptor CXCR4 has been implicated in sarcoma development and has been found to be a prognostic marker for poor clinical outcome. There is growing evidence that overexpression of CXCR4 plays a significant role in development of metastatic disease, especially in directing tumor cells towards the preferential sites of metastases in sarcoma, lung and bone. Although further investigation is necessary to validate these pathways, there is potential for clinical application, particularly in the use of pharmacologic inhibitors of CXCR4 as means of preventing sarcoma metastasis.

Pathobiologic markers of the ewing sarcoma family of tumors: state of the art and prediction of behaviour

Over the past three decades, the outcome of Ewing sarcoma family tumor (ESFT) patients who are nonmetastatic at presentation has improved considerably. The prognosis of patients with metastatic disease at the time of diagnosis and recurrence after therapy remains dismal. Drug-resistant disease at diagnosis or at relapse remains a major cause of mortality among patients diagnosed with ESFT. In order to improve the outcome for patients with potential relapse, there is an urgent need to find reliable markers that either predict tumor behaviour at diagnosis or identify therapeutic molecular targets at the time of recurrence. An improved understanding of the cell of origin and the molecular pathways that regulate tumorigenicity in ESFT should aid us in the search for novel therapies for ESFT. The purpose of this paper is thus to outline current concepts of sarcomagenesis in ESFT and to discuss ESFT patterns of differentiation and molecular markers that might affect prognosis or direct future therapeutic development.