Silver-binding nucleolar organizer regions (AgNORs) have been counted in sections of routinely processed paraffin-embedded tissue blocks and have been shown to assist in the distinction between benign and malignant lesions. We have examined 214 benign and malignant breast lesions by this method. The AgNOR counts were fibroadenomas 1.87 +/- 0.20 (mean +/- SD; n = 39), papillomas 1.92 +/- 0.21 (n = 28), sclerosing adenosis 1.96 +/- 0.24 (n = 23), epitheliosis 2.21 +/- 0.30 (n = 38), lobular carcinoma in situ 2.67 +/- 0.54 (n = 9), intraduct carcinoma 3.75 +/- 1.33 (n = 37), and invasive carcinoma 4.22 +/- 1.18 (n = 40). However, the counts in 25-30 per cent of epitheliosis lesions and intraduct carcinomas overlapped in the region of 2-3 AgNOR dots per nuclear profile. The AgNOR counts in carcinomas were also compared with ploidy and growth phase fractions (S + G2 + M%) by flow cytometry. Thirty-three of the 46 cancers with counts over 3 AgNOR dots per nuclear profile contained aneuploid cells (greater than 10 per cent of the total), whereas 8 of the 12 with counts below 3 comprised diploid cells only (P less than 0.05). Similar trends were noted with regard to growth phase fractions which were 19.15 per cent +/- 12.31 and 13.98 per cent +/- 5.55, respectively, for the two groups (P greater than 0.10). We conclude that this method alone does not offer a reliable histological discriminant for malignancy in the breast. However, AgNOR counting may provide information on breast cancer prognosis supplementary to that obtained from DNA flow cytometric analyses.

Summary Matrix metalloproteinase (MMP) expression was investigated in patients with prostatic adenocarcinoma and benign prostatic hyperplasia (BPH). Forty-one men were studied: 26 had histologically proven prostate cancer, with 14 (54%) showing metastatic disease; 15 patients had BPH. Prostatic tissue was obtained from transurethral resection and needle core biopsies; gelatinolytic activity was determined by zymography. Seven gelatinolytic bands were detected, with molecular weights ranging from > 100 kilodalton (kDa) to 29 kDa. Nine of 14 patients (64%) with skeletal metastases had 92 kDa activity, present in only two of 12 patients (17%) with a negative bone scan, and absent in BPH. The 92 kDa gelatinolytic activity was expressed in 73% of aneuploid tumours compared with 20% of diploid tumours. A 97 kDa gelatinase was expressed in 80% of BPH samples and 23% of carcinoma patients. Enzyme bands of 72, 66 and 45 kDa were equally expressed in malignant tissue, irrespective of metastatic status, but were expressed in fewer BPH patients. The 97, 92, 66 and 45 kDa enzymes were identified as being pro-MMP-9 sequences by Western blotting, using a specific antibody directed against the pro sequence of the mature protein. MMP activity appeared to be increased in malignant prostatic tissue compared with BPH. Pro-MMP-9, in its 92 kDa form, was shown to be exclusively expressed by malignant prostatic tissue, and in particular by tumours that exhibited the aggressive and metastatic phenotype.Prostate cancer is the third most common malignancy in men in England and Wales, with over 9,000 new cases registered every year (Office of Population Censuses and Surveys, 1985).

Tissue transglutaminase (tTgase) is a GTP-bindingCa2÷-dependent enzyme which catalyses the post-translational modification of proteins via e(3,-glutamyl) lysine bridges. Recent evidence suggests that the GTP-binding activity of tTgase may be important in intraceHular signalling thus explaining some of the diverse suggested roles for the enzyme. In the following work a malignant hamster fibrosarcoma (Met B) has been stably transfected with both the full length tTgase cDNA (wild type) and a mutant form of the cDNA whereby the active site cysteine (Cys 277) has been replaced by serine. Expression of this mutant cDNA leads to a protein with GTP binding activity which is deficient of protein crosslinking activity. When synchronised into S-phase and allowed to progress through the cell cycle tTgase transfected clones (both mutant and wild type), when compared to transfected controls, show a delayed progression from S-phase to G2/M when analysed by flow cytometry which appears to be elicited by the G-protein activity of the tTgase.

Summary. Interleukin-6 (IL-6) is the major growth factor for human myeloma cells, exerting its effect through the IL-6 receptor (IL-6R). A soluble form of IL-6R (sIL-6R) has been identified, which increases the sensitivity of myeloma cells to IL-6. In patients with multiple myeloma (MM), serum concentrations of sIL-6R are elevated and associated with poor prognosis. The present study was undertaken to determine whether proteolytic cleavage of IL-6R could contribute to sIL-6R release from human myeloma cells, and also to identify the class of proteinase responsible for this event. Human myeloma cell lines were shown to express IL-6R upon their surface and also to release sIL-6R into culture supernatants. In addition, phorbol 12-myristate 13-acetate (PMA) stimulated a loss of IL-6R from the cell surface, with a corresponding increase in the concentration of sIL-6R in the supernatant. Inhibitors of serine and cysteine proteinases, and tissue inhibitor of metalloproteinase (TIMP) -1 and TIMP-2, were shown to have no effect on the magnitude of sIL-6R release. In contrast, TIMP-3 and a hydroxamatebased metalloproteinase inhibitor (BB-94), inhibited both constitutive and PMA-induced release of sIL-6R. Myeloma cells freshly isolated from the bone marrow of a patient with MM were also shown to express IL-6R upon their surface, and to shed this receptor in response to PMA. These data demonstrate that increased proteolytic cleavage of IL-6R, mediated by a non-matrix-type metalloproteinase, is likely to contribute to the elevated concentrations of sIL-6R found in the serum of patients with MM. Inhibition of sIL-6R release by hydroxamate-based metalloproteinase inhibitors may represent a novel therapeutic approach to the treatment of MM.Keywords: soluble interleukin-6 receptor, shedding, metalloproteinase, multiple myeloma, tissue inhibitor of metalloproteinase-3.

Susceptibility to cell death in adhesion-prevented epithelial cells may thus be regulated by signalling pathways involving Phosphatidylinositol 3-kinase, Janus kinase 2 and protein kinase C. The ability of epithelial tumour cells to invade and metastasize may therefore result from disruption of these pathways.