Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Formalin-fixed, paraffin-embedded tissue is the most widely available material for retrospective clinical studies. In combination with the potential of genomics, these tissues represent an invaluable resource for the elucidation of disease mechanisms and validation of differentially expressed genes as novel therapeutic targets or prognostic indicators. We describe here an approach that, in combination with laser-assisted microdissection allows quantitative gene expression analysis in formalin-fixed, paraffin-embedded archival tissue. Using an optimized RNA microscale extraction procedure in conjunction with real-time quantitative reverse transcriptase-polymerase chain reaction based on fluorogenic TaqMan methodology, we analyzed the expression of a panel of cancer-relevant genes, EGF-R, HER-2/neu, FGF-R4, p21/WAF1/Cip1, MDM2, and HPRT and PGK as controls. We demonstrate that expression level determinations from formalin-fixed, paraffin-embedded tissues are accurate and reproducible. Measurements were comparable to those obtained with matching fresh-frozen tissue and neither fixation grade nor time significantly affected the results. Laser microdissection studies with 5-microm thick sections and defined numbers of tumor cells demonstrated that reproducible quantitation of specific mRNAs can be achieved with only 50 cells. We applied our approach to HER-2/neu quantitative gene expression analysis in 54 microdissected tumor and nonneoplastic archival samples from patients with Barrett's esophageal adenocarcinoma and showed that the results matched those obtained in parallel by fluorescence in situ hybridization and immunohistochemistry. Thus, the combination of laser-assisted microdissection and real-time TaqMan reverse transcriptase-polymerase chain reaction opens new avenues for the investigation and clinical validation of gene expression changes in archival tissue specimens.
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PMID:Quantitative gene expression analysis in microdissected archival formalin-fixed and paraffin-embedded tumor tissue. 1115 80

Despite the recent introduction of real-time PCR methods and cDNA microarrays, competitive PCR techniques continue to play an important role in nucleic acid quantification because of the significantly lower cost of equipment and consumables. In this study, we developed a construct, termed tumor suppressor-internal standard (TS-IS) that produced polycompetitive RNA templates as an internal standard to quantify cellular RNA concentration of tumor suppressor genes. This construct is composed of not only sets of primers for detecting the expression of several tumor suppressor genes (such as pRB, p16(INK4A) 15(INK4B), p14(ARF) p53, and p21(WAF1)), but also HPRT as an endogenous marker. Using an internal standard RNA that was synthesized from the TS-IS construct, we were able to establish optimized conditions for the quantification of tumor suppressor genes with minimal amounts (50 ng) of cellular RNA. In addition, the usefulness of this method was confirmed by analyzing the expression levels of tumor suppressor genes in fourteen hepatoma cell lines as a model. The TS-IS assay that we used was inexpensive and a widely applicable method that permitted the reliable and accurate quantification of tumor suppressor genes.
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PMID:Quantification of tumor suppressor mRNA expression by poly-competitive RT-PCR using a TS-IS that contained multiple internal competitors. 1213 90