Construction of tissue microarrays from prostate needle biopsy specimens

Abstract

Needle biopsies are taken as standard diagnostic specimens for many cancers, but no technique exists for the high-throughput analysis of multiple individual immunohistochemical (IHC) markers using these samples. Here we present a simple and highly reliable technique for constructing tissue microarrays (TMAs) from prostatic needle biopsies. Serial sectioning of the TMAs, called 'Checkerboard TMAs', facilitated expression analysis of multiple proteins using IHC markers. In total, 100% of the analysed biopsies within the TMA both preserved their antigenicity and maintained their morphology. Checkerboard TMAs will allow the use of needle biopsies (i) alongside other tissue specimens (trans-urethral resection of prostates and prostatectomies in the case of prostate cancer) in clinical correlation studies when searching for new prognostic markers, and (ii) in a diagnostic context for assessing expression of multiple proteins in cancers from patients prior to treatment.

Figure 1

Construction of Checkerboard TMA from prostatic needle biopsies. (A) Prostatic needle biopsies embedded horizontally within a paraffin block (bottom) and H&E sections from this block (top). (B) Checkers (4 × 2 × 2 mm³) cut from the original paraffin block containing the prostatic needle biopsy specimen was painted on the surface opposite that containing the biopsy, alternately with blue and red dyes. (C) Checkers positioned in a 36 × 24 × 5 mm³ stainless steel mould (Raymond A Lamb Ltd, UK) so that each biopsy specimen now had a vertical orientation. (D) Finished Checkerboard TMA block in which the cross-sections of the vertically positioned biopsies are seen (arrow). (E) Haematoxylin and eosin-stained section (4 μm) obtained from the Checkerboard TMA block.

Figure 2

Analysis of sections obtained from a Checkerboard TMA. (A) Serial sections (× 20) from a single biopsy specimen that contained both cancer (thin arrow) and prostatic intra-epithelial neoplasia (PIN) (arrowhead) stained by H&E, PSA, CAM 5.2 and LP34. (B) Serial sections (× 20) of second biopsy specimen containing both cancer (thin arrow) in the deeper part of the biopsy and benign glands on the surface (arrowhead) stained by H&E, PSA, CAM 5.2 and LP3. The surface of the biopsy that was originally cut for diagnosis of cancer is seen (dotted arrow). (C) Comparison of a tissue core (× 20) from conventional TMA (top panel) with a biopsy core (× 20) from the Checkerboard TMA (lower panel). The side of the needle biopsy originally cut for diagnostic purposes can be seen (arrow).