Immunohistochemical localization of human kallikreins 6, 10 and 13 in benign and malignant prostatic tissues

Abstract

Human kallikreins 6, 10 and 13 (hK6, hK10 and hK13) are expressed by many normal, mainly glandular tissues, including prostatic epithelium. Some kallikreins may function as tumor suppressors or are downregulated during cancer progression. The aim of this study was to evaluate the immunoexpression of these kallikreins in benign and malignant prostatic tissues and correlate their expression with prostate cancer (PC) prognosis. Included in the study were 25 cases of nonmalignant prostate and 179 cases of PC. Among them, 122 PC cases were immunostained for hK6, 94 for hK10 and 113 for hK13, respectively. The follow-up period for a subset of 68 patients who had undergone radical prostatectomy (RP) was 1-58 months (mean ¼ 13.471.7 and median ¼ 8.0 months). A cutoff value of 0.2 lg/l of serum PSA was established as a biochemical recurrence threshold. Follow-up information was available for 26/55 RP cases stained for hK6, 14/32 cases stained for hK10 and 25/59 cases stained for hK13. Gleason score (GS) 7 carcinomas were stratified as 7a and 7b, according to the primary grade. PC with GS 2-7a were histologically categorized as low malignant (LM) and PC with GS 7b-10 as high malignant (HM). The immunohistochemical method of streptavidinbiotin-peroxidase using monoclonal and polyclonal antibodies was performed. In the benign prostate and in prostatic intraepithelial neoplasia, a cytoplasmic immunostaining of varying intensity was evident. In PC, the immunoexpression of all kallikreins was decreased: 102/122 cases (84%) were positive for hK6, 73/94 (78%) for hK10 and 97/113 (86%) for hK13, respectively. A statistically significant difference in expression was found, in comparison to nonmalignant prostates (P ¼ 0.029, 0.009 and 0.045, respectively). Also, a positive correlation was observed between the immunoexpression of these three kallikreins. Concerning the histological grade, HM-PC expressed all three kallikreins with a slightly higher percentage than LM-PC: 79 vs 88% for hK6, 76 vs 79% for hK10 and 76 vs 92% for hK13. These differences were statistically significant only in the case of hK13 (P ¼ 0.024). Serum PSA did not correlate with kallikrein immunoexpression in PC. Furthermore, there was no significant correlation between kallikrein expression and pathological stage or recurrence, in the cases of RP. All three kallikreins are expressed in the nonmalignant and malignant prostate, with cancer tissues demonstrating slightly lower expression. Expression levels did not correlate with aggressiveness and they do not seem to have value for prostate cancer prognosis.

Co-expression of KLK6 and KLK10 as prognostic factors for survival in pancreatic ductal adenocarcinoma

“…In these tissues the kallikreins can act independently, but also together as part of proteolytic cascades (Petraki et al, 2002b;. The latter seems to be an important mechanism in pancreatic cancer, because expression of KLK10 itself could not be associated with poor survival in PDAC, whereas the co-expression of both kallikreins was significantly associated with poor survival and an R1-resection status, which is an indirect sign for infiltrative and aggressive growth.…”

“…To block nonspecific binding, the membrane was incubated overnight in PBS with 0.1% Tween 20 (T-PBS) containing 5% BSA at 41C. Subsequently, the membrane was incubated for 1 h with the antibody against KLK10 (1 : 1000, see (Petraki et al, 2001(Petraki et al, , 2002a(Petraki et al, , 2003) or b-actin loading control (1 : 5000, no. ab6276, Abcam, Cambridge, UK) in T-PBS and 5% BSA.…”

“…The ductal epithelium and the Langerhans' islets served as positive controls for both kallikreins (Petraki et al, 2001(Petraki et al, , 2002a(Petraki et al, , 2003. Negative controls were performed for all studied tissues by omitting the primary antibody (KLK6 and KLK10) or by replacing it by non-immune serum (dilution 1 : 500) (see Supplementary Data 1).…”

“…Its role in carcinogenesis is unsolved as it is downregulated in some tumours such as breast cancer and acute lymphoblastic leukaemia, whereas overexpressed in ovarian, prostate or renal cancer Petraki et al, 2003Petraki et al, , 2006Zhang et al, 2006). Unfortunately, the function of KLK10 protein remains poorly documented, neither the activators nor the substrates for KLK10 are actually known (Zhang et al, 2006).…”

Prostatic trypsin-like kallikrein-related peptidases (KLKs) and other prostate-expressed tryptic proteinases as regulators of signalling via proteinase-activated receptors (PARs)

“…Not detected ND (Rajapakse et al, 2005;Kishi et al, 2006;Stefansson et al, 2008) 9 (Luo et al, 2001a;Petraki et al, 2002Petraki et al, , 2003a 11 Tryptic Arg SF; N; B Up c (Mitsui et al, 2000;) Nakamura et al, 2003; Brought to you by | University of Queensland -UQ Library Authenticated Download Date | 9/14/15 3:38 AM (Memari et al, 2007a; 13 Tryptic Arg)Lys SF; N; B; C Down Kapadia et al, 2004;(Kapadia et al, 2003;Petraki et al, 2003a,b;Borgono et al, 2007a) Shaw and 14 Tryptic Arg)Lys, Tyr, Phe, Tyr, Gly, Leu SF; N Up c (Brattsand et al, 2005;Felber et al, 2005;(Borgono et al, 2007c;Diamandis, 2007) Oikonomopoulou et al, 2006;Borgono et al, 2007a,b,c;Stefansson et al, 2008) …”