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Application of array CGH on archival formalin-fixed paraffin-embedded tissues including small numbers of microdissected cells.

ABSTRACT: Array-based comparative genomic hybridisation (aCGH) has diverse applications in cancer gene discovery and translational research. Currently, aCGH is performed primarily using high molecular weight DNA samples and its application to formalin-fixed and paraffin-embedded (FFPE) tissues remains to be established. To explore how aCGH can be reliably applied to archival FFPE tissues and whether it is possible to apply aCGH to small numbers of cells microdissected from FFPE tissue sections, we have systematically performed aCGH on 15 pairs of matched frozen and FFPE astrocytic tumour tissues using a well-established in-house human 1 Mb BAC/PAC genomic array. By spiking tumour DNA with normal DNA, we demonstrated that at least 70% of tumour DNA was required for reliable aCGH analysis. Using aCGH data from frozen tissue as a reference, it was found that only FFPE astrocytic tumour tissues that supported PCR amplification of >300 bp DNA fragment provided high quality, reproducible aCGH data. The presence of necrosis in a tissue specimen had an adverse effect on the quality of aCGH, while fixation in formalin for up to 96 h of fresh tissue did not appear to affect the quality of the result. As little as 10-20 ng DNA from frozen or FFPE tissues could be readily used for aCGH analysis following whole genome amplification (WGA). Furthermore, as few as 2000 microdissected cells from haematoxylin-stained slides of archival FFPE tissues could be successfully used for aCGH investigations when WGA was used. By careful assessment of DNA integrity and review of histology, to exclude necrosis and select specimens with a high proportion of tumour cells, it is feasible to preselect archival FFPE tissues adequate for aCGH analysis. With the help of microdissection and WGA, it is also possible to apply aCGH to histologically defined lesions, such as carcinoma in situ.

SUBMITTER: Johnson NA

PROVIDER: S-EPMC2815849 | biostudies-literature | 2006 Sep

REPOSITORIES: biostudies-literature

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Application of array CGH on archival formalin-fixed paraffin-embedded tissues including small numbers of microdissected cells.

Johnson Nicola A NA Hamoudi Rifat A RA Ichimura Koichi K Liu Lu L Pearson Danita M DM Collins V Peter VP Du Ming-Qing MQ

Laboratory investigation; a journal of technical methods and pathology 20060605 9

Array-based comparative genomic hybridisation (aCGH) has diverse applications in cancer gene discovery and translational research. Currently, aCGH is performed primarily using high molecular weight DNA samples and its application to formalin-fixed and paraffin-embedded (FFPE) tissues remains to be established. To explore how aCGH can be reliably applied to archival FFPE tissues and whether it is possible to apply aCGH to small numbers of cells microdissected from FFPE tissue sections, we have sy ...[more]

PMID: 16751780

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Project description:There is increasing acceptance of the critical importance of correlating the morphologic features of tissue with the data obtained from various molecular analytic techniques. Access to archived formalin-fixed and paraffin-embedded (FFPE) tissue specimens via shotgun-based proteomic analyses may, therefore, open new avenues for both prospective and retrospective translational research. However, one of the remaining issues in performing comparative proteomic measurements among FFPE tissues relates to potential variability in protein composition and retrieval based on length of storage periods. Optimized protein extraction and digestion procedures for handling FFPE tissues are coupled with the capillary isotachophoresis-based proteome technology to evaluate the effects of length of storage period on archival tissue proteome analysis across 10 archived uterine mesenchymal tumor tissue blocks, including 9 uterine leiomyomas dating from 1990 to 2002 and a single case of alveolar soft part sarcoma (ASPS) from 1980. Several statistical measures, including the Pearson correlation coefficient, coefficient of variance, k-means clustering, and ANOVA, are employed to evaluate the possibility of an archival effect on individual proteins or groups of proteins within nine leiomyomas. Low abundance proteins may be more susceptible to the long-term storage as these proteins are more difficult to be retrieved and extracted as the tissue block ages in paraffin. Despite using tissue blocks stored for as many as 28 years, high confidence and comparative proteome analysis between the leiomyomas and the sarcoma is achieved. Though sharing over 1800 common proteins in a core set, a total of 80 proteins unique to the sarcoma are identified distinguishing the ASPS from the leiomyomas. Vacuolar proton translocating ATPase 116 kDa subunit isoform a3, one of the unique proteins expressed in the ASPS, is further validated by immunohistochemistry (IHC). Although IHC is highly sensitive and provides the subcellular resolution, mass spectrometry-based proteome profiling enables global identification and quantification of thousands of proteins without a priori knowledge of individual proteins being analyzed or the need of validated antibodies.

Dataset Information

Application of array CGH on archival formalin-fixed paraffin-embedded tissues including small numbers of microdissected cells.

Publications

Application of array CGH on archival formalin-fixed paraffin-embedded tissues including small numbers of microdissected cells.

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