J Cancer Res Clin Oncol (1995) 121:64-68 9 Springer-Verlag 1995 RAPID COMMUNICATION Joachim Rehbock 9 Peter Buchinger 9 Andrea Hermann Carlos Figueroa Identification of immunoreactive tissue kallikrein in human ductal breast carcinomas Received: 30 June 1994 / Accepted: 25 October 1994 Abstract Various proteases have been shown to be present in malignant breast tissue. Although the question of the involvement of tissue kallikrein, a serine protease, in the pathophysiology of tumours has been raised, the presence of this enzyme in human breast carcinoma has so far not been examined. In the present study, both neoplastic and normal human breast are scanned by immunocytochemistry for the presence and cellular localization of tissue kalli- krein. In the healthy breast, tissue kallikrein was observed as a deposit of immunoreactive material that localized in the apical portion of duct cells. In the malignant breast tumours surveyed, the enzyme was observed only in ductal carcinomas, whereas lobular carcinomas were devoid of immunostaining. In ductal carcinomas, the immunoreactiv- ity for tissue kallikrein appeared to be associated with gradations of malignancy, being absent in dedifferentiated tumours. The presence of tissue kallikrein in malignant breast tumours poses the question of the role of this enzyme in malignant breast tissue. The enzyme may participate within the tissue either in proteolytic processes (it has been shown to activate procollagenase) or by enhancing vascu- larity or mitogenicity by the generation of kinins. Key werds Tissue kallikrein 9Breast carcinoma Immunocytochemistry 9Proteases 9 Human Introduction Cofactors of malignant transformation and mitogenic agents are involved in the pathogenesis of malignant tumours (Khokka et al. 1991). Furthermore, proteolytic enzymes play a crucial role in promoting tissue invasion and metastasis. Tissue kallikrein, which belongs to the family of serine proteases, may influence the mitogenic progression of neoplastic disease, either directly or by its ability to activate pro forms of biologically active sub- stances (Bhoola et al. 1992; Tschesche et al. 1989). Evidence from animal models indicates that kinins gener- ated in malignant lesions increase vascular permeability (Matsumura et al. 1988). In addition, analysis of plasma from advanced-stage cancer patients has provided evidence for a systemic activation of the kallikrein/kinin system in these patients when compared to healthy individuals (Matsumura et al. 1991). The kinins formed may increase blood flow in the vascular bed of the tumours, and facilitate the nutrient and oxygen supply to the tumour cells. The aim of the present study was to examine the presence of tissue kallikrein in human breast carcinomas and healthy breast tissue by immunocytochemical methods. Materials and methods Human breast cancer tissue and normal breast tissue was collected at surgery. Histological diagnosis and assessment of the grade of differentiation were performed by clinical histopathologists according to the schedule proposed by Bloom and Richardson (1957), in which pleomorphism, the numbers of mitosis and the tubular differentiation are estimated independently. This results in a classification of turnouts as highly (grade 1), moderately (grade 2) or poorly (grade 3) differ- entiated. Oestrogen and progesterone receptors were determined either by the DCC (dextran charcoal) method (EORTC Breast Cancer Cooperative Group 1980) or by immunocytochemistry (kits from Abbot Chicago, Illinois, USA: PG-E ICA and PG-R ICA Monoclonal). J. Rehbock (~) 9 R Buchinger 9 A. Hermann I. Frauenklinik der Universit~t, Maistrasse 11, D-80337 Miinchen, Germany C. Figueroa Instituto de Histologia y Patologia, Universidad Austral de Chile, Valdivia, Chile Tissue preparation Both normal tissue and primary carcinomas of the breast were fixed in 1.6% formalin buffered to pH 7 for 24 h at room temperature. After fixation the tissue samples were dehydrated in a series of ethanol treatments and embedded in paraffin wax.