Evaluation of genetic stability of the SYT gene rearrangement by break-apart FISH in primary and xenotransplanted synovial sarcomas

High-risk gastrointestinal stromal tumour (GIST) and synovial sarcoma display similar angiogenic profiles: a nude mice xenograft study

Background

Gastrointestinal stromal tumour (GIST) is the most common primary mesenchymal tumour of the gastrointestinal tract. Spindle cell monophasic synovial sarcoma (SS) can be morphologically similar. Angiogenesis is a major factor for tumour growth and metastasis. Our aim was to compare the angiogenic expression profiles of high-risk GIST and spindle cell monophasic SS by histological, immunohistochemical and molecular characterisation of the neovascularisation established between xenotransplanted tumours and the host during the initial phases of growth in nude mice.

Methods

The angiogenic profile of two xenotransplanted human soft-tissue tumours were evaluated in 15 passages in nude mice using tissue microarrays (TMA). Tumour pieces were also implanted subcutaneously on the backs of 14 athymic Balb-c nude mice. The animals were sacrificed at 24, 48, and 96 h; and 7, 14, 21, and 28 days after implantation to perform histological, immunohistochemical, and molecular studies (neovascularisation experiments).

Results

Morphological similarities were apparent in the early stages of neoplastic growth of these two soft-tissue tumours throughout the passages in nude mice and in the two neovascularisation experiments. Immunohistochemistry demonstrated overexpression of pro-angiogenic factors between 24 h and 96 h after xenotransplantation in both tumours. Additionally, neoplastic cells coexpressed chemokines (CXCL9, CXCL10, GRO, and CXCL12) and their receptors in both tumours. Molecular studies showed two expression profiles, revealing an early and a late phase in the angiogenic process.

Conclusion

This model could provide information on the early stages of the angiogenic process in monophasic spindle cell SS and high-risk GIST and offers an excellent way to study possible tumour response to antiangiogenic drugs.

Models of biobanking and tissue preservation: RNA quality in archival samples in pathology laboratories and "in vivo biobanking" by tumor xenografts in nude mice-two models of quality assurance in pathology

Tissue banks represent essential resources and platforms for biomedical research serving basic, translational, and clinical research projects. In this article, we describe 2 models of biobanking and tissue preservation with different approaches and aims. Archive tissue biobanking is described here as a resource of residual pathology tissues for translational research, which represents the huge clinical heterogeneity. In this context, managing of tissues and RNA quality in archive tissue are discussed. The other model of tissue biobanking is referred to as xenograft tissue banking, which represents an alternative method for obtaining large amounts of tissue, over an indefinite period, in so far as the tumor can be transferred in vivo over generations, maintaining the histological and genetic particularities. A description of the method and examples of the application are given with particular emphasis on sarcomas (Ewing's sarcoma/primitive neuroectodermal sarcoma, synovial sarcomas, and rhabdomyosarcomas) and early stages of tumor angiogenesis in sarcomas.

Diagnostic utility of dual-color break-apart chromogenic in situ hybridization for the detection of rearranged SS18 in formalin-fixed, paraffin-embedded synovial sarcoma

Pathological diagnosis of synovial sarcoma is often problematic due to its broad spectrum of histology. Because synovial sarcoma consistently carries a specific chromosomal translocation, t(X;18), and its derivative chimeric gene, either SS18-SSX1 or SS18-SSX2, detecting these abnormalities by reverse transcription polymerase chain reaction or fluorescence in situ hybridization has been recognized as a powerful aid for diagnosis. Recently, chromogenic in situ hybridization, which enables simultaneous visualization of both genomic abnormality and the morphology of tumor cells, has gained attention. This study investigated the diagnostic utility of dual-color break-apart chromogenic in situ hybridization as a novel method for detecting SS18 rearrangement in synovial sarcoma. Formalin-fixed, paraffin-embedded tissue samples from 16 cases of synovial sarcoma and 10 cases of 5 other types of soft tissue sarcoma were collected. Dual-color break-apart probes were designed against the genomic region adjacent to SS18. Fluorescence and chromogenic in situ hybridization studies were performed using the same sections. In both assays, the number of signals was counted for sixty nuclei per sample. Scoring ratios (unpaired signals/paired signals) were calculated. Subsequently, SS18-SSX1 and SS18-SSX2 were examined by reverse transcription polymerase chain reaction. The results of chromogenic in situ hybridization, fluorescence in situ hybridization, and reverse transcription polymerase chain reaction were correlated. Unpaired signals were clearly observed in all the synovial sarcoma samples, which mostly indicated rearranged SS18. Synovial sarcoma and non-synovial sarcoma samples were clearly distinguished from each other by the scoring ratios. Reverse transcription polymerase chain reaction demonstrated SS18 chimeric gene transcripts in all the synovial sarcoma cases, while no fusion genes were detected in the non-synovial sarcoma cases. Taken together, unpaired signals in synovial sarcoma reflected rearranged SS18. The present chromogenic in situ hybridization-based SS18 rearrangement detection system provides a highly sensitive and specific method for the diagnosis of synovial sarcoma. Chromogenic in situ hybridization-based methods have great potential for routine use in the diagnosis of synovial sarcoma.

Analysis of biological prognostic factors using tissue microarrays in neuroblastic tumors

BACKGROUND

Neuroblastic tumors (NT) are pediatric neoplasms with a heterogeneous genetic profile. They present genotypic alterations of prognostic value, the study of which is mandatory in designing therapeutic management. Tissue microarrays (TMA) from paraffin material allow the analysis of a large number of cases with minimal costs. The main purpose of the present study is to analyze specific genetic markers of neuroblastic tumors included in TMAs and determine their prognostic value. We compare the results obtained by different molecular techniques at different substrates to evaluate the feasibility of these assays.

PROCEDURE

One hundred thirty-nine samples were included in four different TMAs. We performed FISH assays to determine the status of MYCN gene, 1p36 region and 17q23 arm. The prognostic value of the genetic markers as well as the statistical correlation among clinical variables and outcome were analyzed by SPSS.

RESULTS

MYCN amplification was detected in 35.3% of the cases, whereas 1p36 deletion and 17q23 gain was observed in 46.8% and 58.3% of the cases, respectively. An adverse prognosis was noted among these patients. Other adverse factors were age (>18 months) as well as high stage of disease (stage 4). Phenotypic signs of differentiation correlated with good outcome.

CONCLUSION

Retrospective studies using paraffin-embedded tissues assembled in TMA are a useful tool for the analysis of prognostic factors in NT.

Tissue microarrays analysis in chondrosarcomas: light microscopy, immunohistochemistry and xenograft study

Background

Chondrosarcoma (Chs) is the third most frequent primary malignant tumour of bone and can be primary or secondary, the latter results mainly from the malignant transformation of a benign pre-existing tumour.

Methods

All the cases diagnosed as Chs (primary tumours, recurrences and/or metastasis and xenotransplanted Chs) from the files of our Department were collected. Only cases with paraffin blocks available were selected (Total 32 cases). Six Tissue Microarrays (TMAs) were performed and all the cases and biopsies were distributed into the following groups: a) only paraffin block available from primary and/or metastatic tumours (3 TMAs), b) paraffin block available from primary and/or metastatic tumours as well as from the corresponding Nude mice xenotransplant (2 TMAs), c) only paraffin block available from xenotransplanted Chs (1 TMA). A reclassification of all the cases was performed; in addition, conventional hematoxylin-eosin as well as immunohistochemistry staining (S100, SOX-9, Ki-67, BCL-2, p53, p16, CK, CD99, Survivin and Caveolin) was analyzed in all the TMA.

Results

The distribution of the cases according to the histopathological pattern and the location of tumours were as follows: fourteen Grade I Chs (all primaries), two primary Grade II Chs, ten Grade III Chs (all primaries), five dedifferentiated Chs (four primaries and one primary with metastasis), and two Chs from cell cultures (Ch grade III). One recurrent extraskeletal myxoid Chs was included as a control in the TMA. Although there was heterogeneity in immunohistochemistry results of the different material analyzed, S100, SOX-9, Caveolin and Survivin were more expressed. The number of passages in xenotransplants fluctuated between 1 and 13. Curiously, in Grade I Chs, these implanted tumours hardly grew, and the number of passages did not exceed one.

Conclusion

The study of Chs by means of TMA techniques is very important because it will improve the assessment of different antibodies applied in the immunohistochemical assays. Xenotransplanted tumours in TMA improve knowledge concerning the variability in the morphological pattern shown by these tumours during the evolution in nudes.

Tissue microarrays: applications in study of p16 and p53 alterations in Ewing's cell lines

Background

Tissue microarrays (TMAs) are used to study genomics and proteomics in several tumour tissue samples. Cell lines (CC) are of great importance in the study of the genetic changes in tumours, and some reveal several aspects of tumour oncogenesis. There are few published reports on Ewing's tumours with TMAs including original tumours (OT) and corresponding CC.

Methods

We have performed four TMAs, from 3 OT and the corresponding CC of successive in vivo and in vitro tumour passages. Xenotransplant CC in nude mice from OT (XT/OT) was made. Subsequently multiple XT were performed and in vitro XT cell line (CC/XT) was obtained. In vivo re-inoculation of CC/XT (XT/CC) was planned. TMAs with the successive tumour passages that grew in nude mice (XT/OT and XT/CC) were analyzed by morphologic pattern (Hematoxilin/eosin), immunohistochemical staining (CD99, FLI1, p16, p53, ki-67), fluorescent in situ hybridization-FISH-(EWSR1 break apart, p16 and p53 status) and gene fusion types.

Results

Heterogeneous results of the p16, p53 and ki67 in OT, XT/OT, CC/XT and XT/CC were observed. The three cell lines revealed EWS/FLI1 rearrangements. p16 gene was deleted only in one case. The deletion was detected by FISH and confirmed by PCR assays. A p53 alteration was found in the second case with monosomy and subsequently polysomic status of chromosome 17 during the evolution of CC. The PCR study revealed p53 mutation. The third case showed hypermethylation in the promoter of p16. The growth of the tumour in nude mice was more accelerated when the inoculation was performed from the CC/XT, increasing progressively over the passages. The third case did not reveal tumour growth in nude mice after the re-inoculation of CC/XT.

Conclusion

The study of several cores from original tumours and successive tumour passages in TMAs facilitated the analysis of the genetic alteration and protein expression in Ewing's tumours.