Immunofluorometric quantitation and histochemical localisation of kallikrein 6 protein in ovarian cancer tissue: a new independent unfavourable prognostic biomarker

Human kallikrein 6 protein is a newly discovered human kallikrein. We determined the amount of human kallikrein 6 in extracts of 182 ovarian tumours and correlated specific activity (ng hK6 mg(-1) total protein) with clinicopathological variables documented at the time of surgical excision and with outcome (progression free survival, overall survival) monitored over a median interval of 62 months. Thirty per cent of the tumours were positive for human kallikrein 6 (>35 ng hK6 mg(-1) total protein). Human kallikrein 6-specific immunohistochemical staining of four ovarian tissues that included benign, borderline and malignant lesions indicated a cytoplasmic location of human kallikrein 6 in tumour cells of epithelial origin, although the intensity of staining was variable. Tumour human kallikrein 6 (ng hK6 mg(-1) total protein) was higher in late stage disease, serous histotype, residual tumour >1 cm and suboptimal debulking (>1 cm) (P<0.05). Univariate analysis revealed that patients with tumour human kallikrein 6 positive specific activity were more likely to suffer progressive disease and to die (hazard ratio 1.71 (P=0.015) and 1.88 (P=0.022), respectively). Survival curves demonstrated the same (P=0.013 and 0.019, respectively). Multivariate analysis revealed that human kallikrein 6 positivity was retained as an independent prognostic variable in several subgroups of patients, namely those with (low) grade I and II tumours (hazard ratio progression free survival 4.3 (P=0.027) and overall survival 4.1 (P=0.023)) and those with optimal debulking (hazard ratio progression free survival 3.8 (P=0.019) and overall survival 5.6 (P=0.011)). We conclude that tumour kallikrein 6 protein levels have utility as an independent adverse prognostic marker in a subgroup of ovarian cancer patients with otherwise apparently good prognosis.     

Increased insulin-like growth factor binding protein-2 (IGFBP-2) gene expression and protein production lead to high IGFBP-2 content in malignant ovarian cyst fluid.

Expression of insulin-like growth factor-I (IGF-I), its receptor and IGF-binding proteins (IGFBPs) by ovarian cancer cells and its mitogenic effect on these cells in vitro, suggest that IGF-I may have a role in regulation of human ovarian cancer. We have recently shown IGFBP-2 to be markedly elevated in malignant ovarian cyst fluid in vivo. To identify the origin of increased IGFBP-2 in these cyst fluids, the gene expression and protein content of IGFBP-2 were investigated in 14 malignant and four benign epithelial ovarian neoplasms. IGFBP-2 mRNA was detected in all ovarian specimens and was 2- to 30-fold higher in malignant than in benign neoplasms. Within the malignant tissues IGFBP-2 mRNA levels correlated with the aggressiveness of the tumour and were higher in invasive tumours than in those with borderline pathology. Southern blot analysis revealed no amplification of IGFBP-2 gene in the DNA samples from ovarian tumours regardless of their nature. IGFBP-2 was the major binding protein in tissue extracts, as measured by both Western ligand blotting and immunoblotting, and was significantly higher in malignant than in benign neoplasms. These findings were further supported by immunohistochemical detection of IGFBP-2 in tumour sections. Our data suggest that increased local production by the tumour in vivo is responsible for the increased IGFBP-2 levels in the cyst fluid bathing the ovarian malignancy. This may represent an autocrine regulatory mechanism for IGF-I proliferative effect of ovarian cancer.     

人组织型激肽释放酶6在卵巢上皮性肿瘤组织中的表达及其与临床病理特征和预后的关系(英文)

Objective: The aim of this study was to approach the relationship between the expression of human kallikrein 6 (hK6) in ovarian neoplasm and the clinicopathologic variables and prognosis for finding a new tumor marker for ovarian cancer. Methods: Through immunohistochemistry to examine the expression of hK6 in 19 cases with benign, 11 cases with borderline and 45 cases with malignant ovarian neoplasms and statistically analyzed whether the expression of hK6 correlated with the clinicopathologic variables an...     

人组织型激肽释放酶6在卵巢上皮性肿瘤中的表达及其与临床病理特征和预后的关系

目的 探讨人组织型激肽释放酶6(hK6)在卵巢肿瘤组织中的表达与临床病理特征和预后的关系.方法 通过免疫组化SP法检测hK6在19例良性卵巢上皮性肿瘤、11例交界性卵巢上皮肿瘤和45例卵巢癌中的表达,分析其表达与卵巢癌患者年龄、原发肿瘤大小、肿瘤组织学类型、分化程度、临床分期和淋巴结转移等临床病理特征和患者预后的关系,并探讨其临床意义.结果 hK6在良性、交界性和恶性卵巢肿瘤组织中的阳性表达率分别为15.8%、27.3%和60.0%,卵巢癌组织中的hK6阳性表达率明显高于良性和交界性肿瘤(P<0.01).hK6的阳性表达与患者年龄、原发肿瘤大小以及肿瘤组织学类型无关,而与肿瘤组织分化程度、临床分期及淋巴结转移密切相关.hK6在中、低分化卵巢癌组织中的表达率(68.4%)明显高于高分化者(14.3%,P<0.05),在Ⅲ期卵巢癌组织中的阳性表达率(76.7%)显著高于Ⅰ～Ⅱ期(26.7%,P<0.01),在有淋巴结转移者的卵巢癌组织中的阳性表达率(77.8%)明显高于无淋巴结转移者(33.3%,P<0.01),在术后3年内复发、转移、死亡患者的卵巢癌组织中的阳性表达率(75.0%)高于术后3年内病情稳定者(42.9%,P<0.05).结论 hK6在卵巢癌组织中的表达明显高于良性和交界性卵巢肿瘤组织,且在临床晚期、组织分化差、有淋巴结转移、预后差的卵巢癌中高表达,提示hK6可能是一种新的反映卵巢癌恶性程度和预后的肿瘤标志物.     

Human kallikrein 6 degrades extracellular matrix proteins and may enhance the metastatic potential of tumour cells.

Human kallikrein 6 (hK6), a trypsin-like serine protease, is a newly identified member of the kallikrein gene family. Its involvement in inflammatory CNS lesions and in demyelination has been reported. Recent work has suggested that expression of this enzyme is significantly elevated in patients with ovarian cancer. We have identified many tumour cell lines that secrete hK6, but its physiological role is unknown. Here, we try to unveil the role of this kallikrein in the metastasis and invasion of tumour cells. We demonstrate that purified human recombinant hK6 can cleave gelatin in zymography and can efficiently degrade high-molecular-weight extracellular matrix proteins such as fibronectin, laminin, vitronectin and collagen. In Boyden chamber assays, we found that tumour cells treated with a neutralizing hK6 antibody migrate less than control cells. We conclude that hK6 might play a role in the invasion and metastasis of tumour cells and may be a candidate therapeutic target.     

Prognostic value of human kallikrein 10 expression in epithelial ovarian carcinoma.

PURPOSE: Human kallikrein 10 (hK10; also known as the normal epithelial cell-specific 1 gene and protein) is a secreted serine protease, which belongs to the human kallikrein family. It has been reported that hK10 is down-regulated in breast and prostate cancer cell lines and that it may function as a tumor suppressor. Recently, we developed a highly sensitive and specific immunoassay for hK10 and found that this protein is abundantly expressed in ovarian tissue. In this study, we measured quantitatively hK10 levels in ovarian cancer cytosolic extracts and evaluated the prognostic value of this biomarker in ovarian cancer. EXPERIMENTAL DESIGN: Specimens from eight normal ovarian tissues, eight ovarian tissues with benign disease, and 182 ovarian tumors were investigated. RESULTS: hK10 concentration in ovarian tumor cytosols ranged from 0 to 84 ng/mg of total protein, with a median of 2.6. This median was highly elevated in comparison with normal and benign ovarian tissues (P < 0.001). A cutoff of 1.35 ng/mg was selected to categorize tumors as hK10 high and hK10 low. With chi(2) test and Fisher's exact test, high concentration hK10 was found to be associated with advanced disease stage, serous histological type, suboptimal debulking, and large residual tumor (>1 cm; all P < 0.05). hK10 status was additionally correlated with clinical outcome, including progression-free (PFS) and overall survival (OS) using the Cox model. In univariate analysis, we found that patients with hK10 high tumors were more likely to die and relapse, in comparison with patients with hK10 low tumors (hazards ratios for PFS and OS were 1.93 and 2.42, respectively; P < 0.05). Although this correlation disappeared after the entire patient population was subjected to multivariate analysis, it remained significant in the subgroup of patients with stage III/IV ovarian cancer (hazards ratios for PFS and OS were 1.98 and 2.12, respectively; P < 0.05). CONCLUSIONS: Our results indicate that hK10 is a new, independent, unfavorable prognostic marker, especially for late-stage ovarian cancer.     

Human kallikrein 8 (hK8/TADG-14) expression is associated with an early clinical stage and favorable prognosis in ovarian cancer

The purpose of this study was to examine human kallikrein 8 (hK8/TADG-14) expression in epithelial ovarian tumors and to investigate the association of hK8 expression levels with patient survival. Human kallikrein 8 protein (hK8) expression was examined by immunohistochemistry in 74 ovarian adenocarcinomas and 6 normal ovaries. Results of immunostaining were correlated with clinicopathological variables and overall survival of the patients. Human kallikrein 8 gene (KLK8) mRNA expression was examined by semi-quantitative PCR in 35 ovarian tumors and 7 normal ovaries. Expression of hK8 was not detected on the surface epithelium of normal ovaries. In contrast, hK8 expression was detected in 51.4% (38/74) of carcinomas with a significantly higher detection rate of hK8 expression being observed in early stage disease compared to advanced stage disease (p=0.0192). Data analysis using the log-rank test showed hK8 expression correlated significantly with favorable patient survival (p=0.0328). Younger age (p=0.0008), early clinical stage (p<0.0001), and low histological grades of the tumors (p=0.0018) were also associated significantly with a favorable prognosis. In a multivariate model, age (p=0.0186) and clinical stage (p<0.0001) remained associated significantly with overall survival, whereas hK8 expression and histological grade lost their significance. There was significant relationship between the hK8 expression status and KLK8 mRNA expression levels (p=0.0304). Expression of hK8 is increased during the development of ovarian cancer and down-regulated during ovarian cancer progression. Expression of hK8 is a favorable prognostic marker in patients with ovarian cancer.     

Expression of pro-apoptotic (p53, p21, bax, bak and fas) and anti-apoptotic (bcl-2 and bcl-x) proteins in serous versus mucinous borderline ovarian tumours

BACKGROUND: We examined the expression of apoptosis-related proteins in serous versus mucinous borderline ovarian tumours, in comparison with benign and malignant ovarian tumours. MATERIALS AND METHODS: Immunohistochemical expression of pro-apoptotic (p53, p21, bax, bak, fas) and anti-apoptotic proteins (bcl-2, bcl-x) was determined in 34 borderline (19 mucinous, 15 serous), 20 benign (10 mucinous, 10 serous) and 28 malignant ovarian tumours (9 mucinous, 19 serous). RESULTS: A difference in semi-quantitative p53 expression was found between benign and borderline tumours (P = 0.01), but not between borderline and malignant tumours. Increased p21 expression was found in borderline versus benign tumours (P = 0.004). Bcl-2 expression was lower in borderline than in benign (P = 0.01) and malignant tumours (P = 0.02). No difference in bax, bak, fas or bcl-x expression was observed among the three tumour types. Higher percentage of p21 positive cells was found in serous than in mucinous borderline tumours (P < 0.001). Bcl-2 expression was higher in serous than in mucinous forms of benign (P < 0.001), borderline (P < 0.001), and malignant tumours (P < 0.003). No difference in p53, bax, bak, fas or bcl-x expression was observed between serous and mucinous borderline ovarian tumours. CONCLUSION: Although p53 overexpression was a common feature of both mucinous and serous borderline tumours, p21 and bcl-2 overexpression appeared specific to serous tumours.     

Gene expression profiling of human ovarian tumours

There is currently a lack of reliable diagnostic and prognostic markers for ovarian cancer. We established gene expression profiles for 120 human ovarian tumours to identify determinants of histologic subtype, grade and degree of malignancy. Unsupervised cluster analysis of the most variable set of expression data resulted in three major tumour groups. One consisted predominantly of benign tumours, one contained mostly malignant tumours, and one was comprised of a mixture of borderline and malignant tumours. Using two supervised approaches, we identified a set of genes that distinguished the benign, borderline and malignant phenotypes. These algorithms were unable to establish profiles for histologic subtype or grade. To validate these findings, the expression of 21 candidate genes selected from these analyses was measured by quantitative RT-PCR using an independent set of tumour samples. Hierarchical clustering of these data resulted in two major groups, one benign and one malignant, with the borderline tumours interspersed between the two groups. These results indicate that borderline ovarian tumours may be classified as either benign or malignant, and that this classifier could be useful for predicting the clinical course of borderline tumours. Immunohistochemical analysis also demonstrated increased expression of CD24 antigen in malignant versus benign tumour tissue. The data that we have generated will contribute to a growing body of expression data that more accurately define the biologic and clinical characteristics of ovarian cancers.     

Receptors for hormones and growth factors and (onco)-gene amplification in human ovarian cancer.

Receptor status and gene amplification were studied in advanced human ovarian adenocarcinoma tissues, borderline and benign ovarian tumours and normal ovarian tissues. Sixty-five percent (53/82) of ovarian adenocarcinomas, 57% (8/14) of benign/borderline tumours and only 31% (5/16) of normal ovarian tissues studied showed specific 125I-EGF (epidermal growth factor) binding (median: 17; 10; and 0 fmol EGF-R/mg protein, respectively) and a significant increase in progesterone receptor (PgR) levels was observed in these groups (median: 5; 33; and 152 fmol/mg protein, respectively). No correlations were observed between the levels of EGF-R and the levels of either oestrogen receptors (ER) or PgR. All membrane samples of 25 adenocarcinomas studied by Scatchard analysis were positive for insulin-like growth-factor-I receptors (IGF-I-R) and contained higher IGF-I-R levels than membranes of 10 normal ovarian tissues, of which 9 were positive (median: 64 and 26 fmol IGF-I-R/mg membrane protein, respectively). Also, as measured by autoradiography, 37 adenocarcinoma tissues showed a higher expression of IGF-I-R (1.5+ to 4+) than sections derived from 10 normal ovarian tissues (1+). 125I-IGF-I binding was predominantly associated with epithelial tumour cells, the surrounding connective tissue was negative and in several samples high expression of IGF-I-R was found in areas of tumour necrosis. Southern blot analysis of DNAs isolated from 25 ovarian adenocarcinomas revealed no amplification of the IGF-I-R or the EGF-R gene. The HER2/neu gene was amplified only in 2 out of 3 histologically confirmed endometrioid adenocarcinomas studied but not in 22 other tumours. An amplification of the c-myc gene was observed in 28% (7/25) of the tumours. All c-myc-amplified tumours were PgR-negative. No rearrangement was observed for any of the genes studied. In conclusion, ovarian adenocarcinoma tissues show a decrease in PgR levels and an increased expression of IGF-I-R and EGF-R, in the absence of gene amplification, when compared to benign/borderline ovarian tumours and normal ovarian tissues. In addition, amplification of the c-myc and HER2/neu genes, without rearrangement of these genes, occurs in a minority of these tumours.     

Human kallikrein 14: a new potential biomarker for ovarian and breast cancer

Human kallikrein gene 14 (KLK14) is a recently discovered member of the tissue kallikrein family of secreted serine proteases, which includes hK3/prostate-specific antigen, the best cancer biomarker to date. Given that KLK14 is hormonally regulated, differentially expressed in endocrine-related cancers, and a prognostic marker for breast and ovarian cancer at the mRNA level, we hypothesize that its encoded protein, hK14, like hK3/prostate-specific antigen, may constitute a new biomarker for endocrine-related malignancies. The objective of this study was to generate immunological reagents for hK14, to develop an ELISA and immunohistochemical techniques to study its expression in normal and cancerous tissues and biological fluids. Recombinant hK14 was produced in Pichia pastoris, purified by affinity chromatography, and injected into mice and rabbits for polyclonal antibody generation. Using the mouse and rabbit antisera, a sandwich-type immunofluorometric ELISA and immunohistochemical methodologies were developed for hK14. The ELISA was sensitive (detection limit of 0.1 micro g/liter), specific for hK14, linear from 0 to 20 micro g/liter with between-run and within-run coefficients of variation of <10%. hK14 was quantified in human tissue extracts and biological fluids. Highest levels were observed in the breast, skin, prostate, seminal plasma, and amniotic fluid, with almost undetectable levels in normal serum. hK14 concentration was higher in 40% of ovarian cancer tissues compared with normal ovarian tissues. Serum hK14 levels were elevated in a proportion of patients with ovarian (65%) and breast (40%) cancers. Immunohistochemical analyses indicated strong cytoplasmic staining of hK14 by the epithelial cells of normal and malignant skin, ovary, breast, and testis. In conclusion, we report the first ELISA and immunohistochemical assays for hK14 and describe its distribution in tissues and biological fluids. Our preliminary data indicate that hK14 is a potential biomarker for breast and ovarian cancers.     

Human kallikrein 5: a potential novel serum biomarker for breast and ovarian cancer

The kallikrein family is a group of 15 serine protease genes clustered on chromosome 19q13.4. Human kallikrein (hK) gene 5 (KLK5) is a member of this family and encodes for a secreted serine protease (hK5). KLK5 was shown to be differentially expressed at the mRNA level in breast and ovarian cancer. Until now, detection of hK5 protein in either biological fluids or tissues has not been described due to lack of suitable reagents and methods. The aim of this study was to develop immunological reagents and a sensitive and specific fluorometric immunoassay (ELISA) for hK5, to examine the presence of hK5 in human tissues and biological fluids, and to study the possible clinical utility of hK5 as a biomarker for endocrine-related malignancies. Recombinant hK5 protein was produced and purified using a Pichia pastoris yeast expression system. The protein was used as an immunogen to generate mouse and rabbit polyclonal anti-hK5 antibodies. A sandwich-type microplate immunoassay (ELISA) was developed using these antibodies, coupled with a time-resolved fluorometric detection technique. The ELISA assay was then used to measure hK5 in various biological fluids, tissue extracts, and serum samples from normal individuals and patients with various malignancies. The hK5 ELISA immunoassay has a lower detection limit of 0.1 micro g/liter, is specific for hK5, and has no cross-reactivity with other homologous kallikreins. The dynamic range is 0.1-25 micro g/liter, and within-run and between-run coefficients of variation within this range are <10%. hK5 is found in many tissues, with the highest expression levels seen in the skin, breast, salivary gland, and esophagus. hK5 is present at relatively high levels in milk of lactating women. Whereas the levels of hK5 are almost undetectable in serum of normal individuals (male and female) and patients with diverse malignancies, higher concentrations were found in a proportion of patients with ovarian (69%) and breast (49%) cancer. High levels were also detected in ascites fluid from metastatic ovarian cancer patients and in ovarian cancer tissue extracts. In conclusion, we report development of the first immunofluorometric assay for hK5 and describe the distribution of hK5 in biological fluids and tissue extracts. Our preliminary data indicate that hK5 is a potential biomarker in patients with ovarian and breast cancer.     

Expanded human tissue kallikrein family--a novel panel of cancer biomarkers.

The full characterization of the human kallikrein gene locus has allowed identification of all members of this gene family on chromosome 19q13.4 and the establishment of common structural criteria, at both the mRNA and protein level. The human kallikrein gene family now consists of 15 members; their mRNA and protein structure, tissue expression and hormonal regulation patterns have been delineated. In addition to prostate-specific antigen (PSA, hK3), which is an established tumor marker for prostate cancer diagnosis and follow-up, and human glandular kallikrein (hK2), an emerging prostate cancer biomarker, accumulating evidence indicates that many other members of the human kallikrein gene family are also implicated in endocrine-related malignancies. Many kallikreins are differentially regulated in breast, prostate, ovarian and testicular cancers. In addition, preliminary reports indicate that three newly identified kallikreins (hK6, hK10 and hK11) are serum biomarkers for diagnosis and monitoring of ovarian and prostate cancer. The mechanism by which kallikreins might be involved in the pathogenesis and/or progression of cancer is not as yet fully understood. Preliminary reports indicate a possible role of kallikreins in controlling vital processes, like apoptosis, angiogenesis and tumor metastasis by cleavage of critical substrates such as growth factors, hormones or extracellular matrix. In this review, we present data on the differential expression of kallikreins in cancer at both the mRNA and protein levels, and propose future directions of research towards our understanding of the involvement of kallikreins in cancer and their possible diagnostic, prognostic and therapeutic applications.     

Tumour-associated trypsin inhibitor (TATI) and cancer antigen 125 (CA 125) in mucinous ovarian tumours

A tumour-associated trypsin inhibitor (TATI) and the cancer antigen 125 (CA 125) were measured pre- or peroperatively in 30 patients with mucinous ovarian tumours (10 malignant, two borderline and 18 benign) to investigate the separate and combined use of the two markers as a diagnostic tool. In the malignant and borderline cases considered as a whole, TATI was elevated in 83% and CA 125 in 50%. The former marker was increased in one (6%) benign tumour and the latter in another (6%). The combined use of TATI and CA 125 ensured diagnosis of all malignant and borderline tumours. The specificity was 89% and the positive predictive value 86%. In conclusion, in the distinction of malignant and borderline mucinous ovarian tumours from benign ones TATI was a more reliable tumour marker than CA 125. The combined use of TATI and CA 125 ensured diagnosis of all malignant and borderline tumours in the present series.