Tissue arrays > Background Section
Tissue microarray (TMA) is a new high-throughput tool for the study of protein expression pattern in tissues and is increasingly used to evaluate the diagnostic and prognostic importance of biomarkers (8), (9). TMA has many advantages over conventional techniques. Among these advantages are high efficiency, uniform reaction conditions, reagent conservation, multiple built-in controls, reduced damage to donor tissue blocks, automated imaging analysis and rapid linking of molecular changes to clinical variables (8), (9). TMA technology has been applied to renal tumor studies (10), (11, 12). However, to date, there have not been examples of adaptation of TMA technology for renal physiological and pathophysiological studies.
The major criticism of TMA technology is that it uses only a small fraction of a tissue specimen, which may not be representative of the entire specimen or even less of the whole organ. Such potential limitations are especially true for the kidney, which is an organ that is highly heterogeneous in structure. Therefore we have conducted multiple validation studies to optimize the sampling strategy for kidney tissue. Currently, most investigators in TMA-based cancer studies use three 0.6-mm tissue cores. We have made the following modifications for constructing TMA blocks from kidney tissue:
1) The kidney blocks are generated from 3 separate sections of the kidney: cortex, outer medulla and inner medulla/papilla;
2) Considering the complex structural heterogeneity of kidney cortex, tissue cylinders with a diameter of 1.0 mm (the normal thickness of mouse kidney cortex), instead of commonly used 0.6-mm, are generated.
3) Four cores (instead of three as used in tumor studies) are used from each region (cortex, outer medulla or inner medulla/papilla) in each sample.
Preparation of TMA blocks: Initially serial sections (4-µm thick) were cut from each donor block. As noted, four areas in each kidney section were targeted. Using Beecher Instruments Tissue Array (Silver Spring, MD), tissue cylinders with a diameter of 1.0 mm were punched from the four targeted areas in each section of each donor kidney and deposited into a 12 x 13 (156 cores) TMA block. Each block contains 144 cores of kidney tissue samples and 12 cores of normal rat (or mouse) tissue samples as built-in controls. The normal rat or mouse tissue samples (spleen, thymus, muscle, prostate, stomach, skin, brain, pancreas, lung, liver, colon, and heart) were cut from 2 month old animals that had been well perfused with FPAS prior to organ harvest (13). The TMA blocks are heated to 37oC for 30 minutes, and multiple serial 4 µm sections are cut and placed on charged slides. One section is stained with H&E for morphologic evaluation.
Publications for Tissue arrays (6)
Zhang MZ, Yao B, Cheng HF, Wang SW, Inagami T, Harris RC. Renal cortical cyclooxygenase 2 expression is differentially regulated by
angiotensin II AT(1) and AT(2) receptors. Proc Natl Acad Sci U S A (2006) 103:16045-50
View abstract View in PubMed
Macula densa cyclooxygenase 2 (COX-2)-derived prostaglandins serve as important modulators of the renin-angiotensin system, and cross-talk exists between these two systems. Cortical COX-2 induction by angiotensin-converting enzyme (ACE) inhibitors or AT(1) receptor blockers (ARBs) suggests that angiotensin II may inhibit cortical COX-2 by stimulating the AT(1) receptor pathway. In the present studies we determined that chronic infusion of either hypertensive or nonhypertensive concentrations of angiotensin II attenuated cortical COX-2. Angiotensin II infusion reversed cortical COX-2 elevation induced by ACE inhibitors. However, we found that angiotensin II infusion further stimulated cortical COX-2 elevation induced by ARBs, suggesting a potential role for an AT(2) receptor-mediated pathway when the AT(1) receptor was inhibited. Both WT and AT(2) receptor knockout mice were treated for 7 days with either ACE inhibitors or ARBs. Cortical COX-2 increased to similar levels in response to ACE inhibition in both knockout and WT mice. In WT mice ARBs increased cortical COX-2 more than ACE inhibitors, and this stimulation was attenuated by the AT(2) receptor antagonist PD123319. In the knockout mice ARBs led to significantly less cortical COX-2 elevation, which was not attenuated by PD123319. PCR confirmed AT(1a) and AT(2) receptor expression in the cultured macula densa cell line MMDD1. Angiotensin II inhibited MMDD1 COX-2, and CGP42112A, an AT(2) receptor agonist, stimulated MMDD1 COX-2. In summary, these results demonstrate that macula densa COX-2 expression is oppositely regulated by AT(1) and AT(2) receptors and suggest that AT(2) receptor-mediated cortical COX-2 elevation may mediate physiologic effects that modulate AT(1)-mediated responses.
The kidney is not only a primary vitamin D target organ but also is a key site of vitamin D metabolism. Recent studies have shown that vitamin D has important physiologic effects on proliferation and differentiation in a variety of benign and malignant cells. Our preliminary immunohistochemical study showed that vitamin D receptor (VDR) was highly expressed in renal distal tubules and collecting ducts, whereas the renal proximal tubules and glomeruli did not express VDR. These observations led us to study the expression of VDR in various kidney tumors to determine the possible diagnostic utility of VDR. Paraffin tissue microarray (TMA) blocks were constructed containing core cylinders from clear cell (52), papillary (35), chromophobe (20), sarcomatoid (20), and metastatic (59) renal cell carcinomas (RCCs). Oncocytomas (20), normal adult kidneys (12), and normal adult adrenals (6) were also included. In addition, 30 clear cell RCCs and 3 collecting duct carcinomas were also studied using conventional sections. Furthermore, VDR messenger RNA and protein expression was also quantified using real-time reverse transcriptase-polymerase chain reaction and Western blot analysis. Vitamin D receptor was strongly positive in collecting duct carcinomas (100% [3/3], cytoplasmic), papillary RCCs (94% [33/35], cytoplasmic), chromophobe RCCs (85% [17/20], membranous), and oncocytomas (90% [18/20], cytoplasmic with perinuclear accentuation). In contrast, VDR expression was focal/weak and present only in the peripheral regions of clear cell RCCs. Vitamin D receptor was weakly positive in sarcomatoid variant RCCs (88% [14/16]) regardless of the type of associated original RCC. Overall, VDR is a discriminative marker for renal cell tumors. The preferential expression of VDR in chromophobe RCCs, oncocytomas, and collecting duct carcinomas
Tsai WC, Jin JS, Yu JC, Sheu LF. CD10, actin, and vimentin expression in breast phyllodes tumors correlates
with tumor grades of the WHO grading system. Int J Surg Pathol (2006) 14:127-31
View abstract View in PubMed
The discrimination of borderline from malignant primary breast phyllodes (PT) tumor is still unclear. We studied 22 PT cases to investigate the immunohistochemical expression (staining of stromal CD10, SMA [smooth muscle actin], and vimentin) as well as the features of focal glandular atypia to determine whether these correlated with the histopathologic grading system. In our results, the stromal staining of CD10 was positive in 4 of 6 malignant and 2 of 5 borderline PT cases, but negative in all benign PT cases. Stromal actin and intraglandular vimentin-expressive tumor cells were found in 5 of 6 malignant PT cases but not in borderline and benign PT cases. There is a significant difference in the panel of stromal CD10, actin, and vimentin expression between borderline and malignant PT (p<0.05). Besides, the progression of malignant potential breast phyllodes tumor may cause glandular epithelium atypia with loss of polarity.
Hedberg Y, Ljungberg B, Roos G, Landberg G. Expression of cyclin D1, D3, E, and p27 in human renal cell carcinoma
analysed by tissue microarray. Br J Cancer (2003) 88:1417-23
View abstract View in PubMed
Aberrations in the G1/S transition of the cell cycle have been observed in many malignancies and seem to be critical in the transformation process. Few studies have delineated the presence of G1/S regulatory defects and their clinical relevance in renal cell carcinoma (RCC). Therefore, we have examined the protein contents of cyclin D1, D3, E, and p27 in 218 RCCs, using tissue microarray and immunohistochemistry. The results from a subset of tumours were confirmed by Western blotting and immunohistochemical staining of regular tissue sections. Interestingly, low protein contents of cyclin D1 and p27 were associated with high nuclear grade, large tumour size, and poor prognosis for patients with conventional tumours. We further observed substantial differences in the pattern of G1/S regulatory defects between the different RCC subtypes. The majority of both conventional and papillary cases expressed p27; however, chromophobe tumours generally lacked p27 staining. In addition, conventional RCCs often expressed high cyclin D1 protein levels, while papillary RCCs exhibited high cyclin E. In summary, we have shown that G1/S regulatory defects are present in RCC and are associated with clinico-pathological parameters. The pattern of cell cycle regulatory defects also differed between RCC subtypes.
Torhorst J, Bucher C, Kononen J, Haas P, Zuber M, Kochli OR, Mross F, Dieterich H, Moch H, Mihatsch M, Kallioniemi OP, Sauter G. Tissue microarrays for rapid linking of molecular changes to clinical
endpoints. Am J Pathol (2001) 159:2249-56
View abstract View in PubMed
Advances in genomics and proteomics are dramatically increasing the need to evaluate large numbers of molecular targets for their diagnostic, predictive or prognostic value in clinical oncology. Conventional molecular pathology techniques are often tedious, time-consuming, and require a lot of tissue, thereby limiting both the number of tissues and the number of targets that can be evaluated. Here, we demonstrate the power of our recently described tissue microarray (TMA) technology in analyzing prognostic markers in a series of 553 breast carcinomas. Four independent TMAs were constructed by acquiring 0.6 mm biopsies from one central and from three peripheral regions of each of the formalin-fixed paraffin embedded tumors. Immunostaining of TMA sections and conventional "large" sections were performed for two wellestablished prognostic markers, estrogen receptor (ER) and progesterone receptor (PR), as well as for p53, another frequently examined protein for which the data on prognostic utility in breast cancer are less unequivocal. Compared with conventional large section analysis, a single sample from each tumor identified about 95% of the information for ER, 75 to 81% for PR, and 70 to 74% for p53. However, all 12 TMA analyses (three antibodies on four different arrays) yielded as significant or more significant associations with tumor-specific survival than large section analyses (p < 0.0015 for each of the 12 comparisons). A single sample from each tumor was sufficient to identify associations between molecular alterations and clinical outcome. It is concluded that, contrary to expectations, tissue heterogeneity did not negatively influence the predictive power of the TMA results. TMA technology will be of substantial value in rapidly translating genomic and proteomics information to clinic
Tissue microarrays are a method of harvesting small disks of tissue from a range of standard histologic sections and placing them in an array on a recipient paraffin block such that hundreds of cases can be analyzed simultaneously. This technique allows maximization of tissue resources by analysis of small-core biop sies of blocks, rather than complete sections. Using this technology, a carefully planned array can be constructed with cases from pathology tissue block archives, such that a 20-year survival analysis can be performed on a cohort of 600 or more patients by use of only a few microliters of antibody in a single experiment. The reflex criticism of this technique is that the tissue analyzed is not representative, especially in antigens with heterogeneous staining patterns. This review addresses this issue, as well as the issue of antigen preservation or durability, which validates construction of arrays from archives. Strategies and methods of construction and analysis of the arrays are discussed, as well as some other unusual array applications. This technique can provide a highly efficient, high-throughput mechanism for evaluation of protein expression in large cohorts. It has the potential to allow validation of new genes at a speed comparable to the rapid rate of gene discovery afforded by DNA microarrays.
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Last updated on 2007-02-06 Moderated by Ming-Zhi Zhang