Immunohistochemical analysis of bcl-2, bax, bcl-X, and mcl-1 expression in prostate cancers.

Proteins encoded by bcl-2 family genes are important regulators of programmed cell death and apoptosis. Alterations in the expression of these apoptosis-regulating genes can contribute to the origins of cancer, as well as adversely influence tumor responses to chemo- and radiotherapy. Using antibodies specific for the Bcl-2, Bax, Bcl-X, and Mcl-1 proteins in combination with immunohistochemical methods, we examined for the first time the expression of these bcl-2 family genes in 64 cases of adenocarcinoma of the prostate, including 10 Gleason grade 2 to 4 tumors, 21 grade 5 to 7 tumors, 17 grade 8 to 10 tumors, 8 lymph node metastases, and 8 bone metastases. In addition, 24 cases of prostatic intraepithelial neoplasia (PIN) or PIN coexisting with carcinoma were also evaluated. All immunostaining results were scored with regard to approximate percentage of positive tumor cells and relative immunostaining intensity. Expression of the anti-apoptotic protein Bcl-2 was present in 16 of 64 (25%) adenocarcinomas and tended to be more frequent in high grade tumors (Gleason grade 8 to 10; 41%) and nodal metastases (38%) than in lower grade (Gleason 2 to 7) primary tumors (16%; P < 0.05). Bcl-X was expressed in all 64 (100%) tumors evaluated. Bcl-X immunointensity was generally stronger in high grade primary tumors (grade 8 to 10) and metastases compared with PIN and low grade neoplasms (P < 0.0001). In addition, the proportion of specimens with > 50% Bcl-X-immunopositive tumor cells also was higher in advanced grade primary tumors (Gleason 8 to 10) and metastases than in PIN and low grade tumors (Gleason 2 to 7; P < 0.005). The anti-apoptotic protein Mcl-1 was expressed in 52 of 64 (81%) tumors, compared with only 9 of 24 (38%) cases of PIN (P < 0.001). In addition, the percentage of Mcl-1-positive cells was typically higher in Gleason grade 8 to 10 tumors and metastases than in PIN or lower grade tumors (P = 0.025). In contrast, the pro-apoptotic protein Bax was expressed in all prostate cancers evaluated, with high percentages of immunopositive cells and strong immunointensity typically occurring regardless of tumor grade. The findings suggest that expression of several anti-apoptotic members of the bcl-2 gene family, including bcl-2, bcl-X, and mcl-1 increases during progression of prostate cancers, a finding that may be relevant to the hormone-insensitive, metastatic phenotype of most advanced adenocarcinomas of the prostate.     

Decreased annexin I expression in prostatic adenocarcinoma and in high-grade prostatic intraepithelial neoplasia

AIMS: To analyse annexin I expression in prostatic carcinoma. Annexin I belongs to a family of structurally related calcium and phospholipid-binding proteins implicated in signal transduction, DNA replication, cell proliferation and apoptosis. The decreased expression of annexin I, II and VII proteins has been reported in different types of cancer. METHODS AND RESULTS: Using immunohistochemistry, we analysed annexin I expression in 77 cases of prostatic adenocarcinoma (Gleason score 6, N = 40; Gleason scores 7-8, N = 27; and Gleason scores 9-10, N = 10) and high-grade prostatic intraepithelial neoplasia (PIN, N = 50). Immunoreactivity of annexin I in tumour cells was evaluated as negative (< 5% of cells), focally positive (5-25% of cells) or positive (> 25% of cells). In contrast to positive staining in adjacent benign prostatic epithelium, annexin I expression was decreased (focally positive) in 76% of cases of high-grade PIN (P < 0.0001) and was decreased or absent in 81% of prostatic adenocarcinomas (P < 0.0001). Annexin I expression in all higher grade tumours (Gleason scores 7-10) was only focally positive or absent. CONCLUSIONS: Expression of annexin I inversely correlates with the increasing histological grade of prostatic adenocarcinoma. By showing a progressive loss of annexin I expression in high-grade PIN, intermediate-grade and high-grade cancer, our findings suggest that the loss of annexin I expression occurs early in prostatic tumorigenesis and becomes more prominent throughout tumour progression. The loss of expression of annexin I may serve as a useful marker of prostate cancer development and progression.     

Estrogen receptor beta expression in invasive breast cancer

The aim of this work was to determine the extent of estrogen receptor beta (ER-beta) expression in invasive breast cancer (BrCA) and whether ER-beta expression is correlated with response to adjuvant hormonal therapy with tamoxifen (AHTT). Immunohistochemical staining (IHC) for estrogen receptor alpha (ER-alpha) and ER-beta was performed on sections of formalin-fixed and paraffin-embedded tissue from 47 unselected invasive breast carcinomas (BrCA). IHC for ER-beta was also performed on sections of BrCA from 118 women who were treated with mastectomy and AHTT. Survival analysis was performed using the Kaplan-Meier method and the log-rank test. Of the 47 unselected BrCA, 17 (36%) were negative for ER-alpha and of these, 8 (47% of ER-alpha negative cases and 17% of all 47 patients) were ER-beta positive. Five of the 8 ER-alpha negative and ER-beta positive cases were positive for ER biochemically. There was no correlation between ER-beta positivity and overall survival in the unselected group. By contrast, in the group of women treated with AHTT, expression of ER-beta in more than 10% of cancer cells was associated with better survival (P = .0077), even in women with node-negative BrCA (P = .0069). In conclusion, our results show that a significant number of women with BrCA are positive for ER-beta only, and may be determined to be ER-negative when currently available IHC is used. ER-beta status is a significant predictor of response to AHTT in women with BrCA. Larger studies with multivariate analysis are needed to confirm these findings.     

Gleason grading and prognostic factors in carcinoma of the prostate.

Gleason grade of adenocarcinoma of the prostate is an established prognostic indicator that has stood the test of time. The Gleason grading method was devised in the 1960s and 1970s by Dr Donald F Gleason and members of the Veterans Administration Cooperative Urological Research Group. This grading system is based entirely on the histologic pattern of arrangement of carcinoma cells in H&E-stained sections. Five basic grade patterns are used to generate a histologic score, which can range from 2 to 10. These patterns are illustrated in a standard drawing that can be employed as a guide for recognition of the specific Gleason grades. Increasing Gleason grade is directly related to a number of histopathologic end points, including tumor size, margin status, and pathologic stage. Indeed, models have been developed that allow for pretreatment prediction of pathologic stage based upon needle biopsy Gleason grade, total serum prostate-specific antigen level, and clinical stage. Gleason grade has been linked to a number of clinical end points, including clinical stage, progression to metastatic disease, and survival. Gleason grade is often incorporated into nomograms used to predict response to a specific therapy, such as radiotherapy or surgery. Needle biopsy Gleason grade is routinely used to plan patient management and is also often one of the criteria for eligibility for clinical trials testing new therapies. Gleason grade should be routinely reported for adenocarcinoma of the prostate in all types of tissue samples. Experimental approaches that could be of importance in the future include determination of percentage of high-grade Gleason pattern 4 or 5, and utilization of markers discovered by gene expression profiling or by genetic testing for DNA abnormalities. Such markers would be of prognostic usefulness if they provided added value beyond the established indicators of Gleason grade, serum prostate-specific antigen, and stage. Currently, established prognostic factors for prostatic carcinoma recommended for routine reporting are TNM stage, surgical margin status, serum prostate-specific antigen, and Gleason grade.     

Correlation between the nucleolar organizer region in adenocarcinoma of the prostate and the Gleason system]

Using a silver staining, technique, Nucleolar Organizer Region-associated proteins (NORs) were studied on paraffin sections of 25 resected prostatic adenocarcinomas classified with Gleason grading and 11 hyperplastic lesions. Then 7 inclusions was selected for each grade of Gleason system and 7 inclusions of normal prostatic tissue. The mean numbers of argyrophilic nucleolar organizer regions (AgNORs) increased significantly (P less than 0.01) from normal prostatic tissue to Gleason 5. The data indicate that AgNORs counts may help distinguish between each grade of Gleason system. It was concluded that the AgNOR technique provides a significant kinetic evaluation of prostatic adenocarcinoma and its prognostic study.     

Evidence for cell-specific changes with age in expression of oestrogen receptor (ER) alpha and beta in bone fractures from men and women

Oestrogen is recognized as important for maintaining bone mass in men and women. Oestrogen receptor (ER) alpha and the recently described ER-beta are both expressed in bone cells, but have different affinities for oestrogen agonists and plant oestrogens, which could be important in developing treatments for bone loss in both men and women. It is unclear, however, which isoform predominates in bone; cell type and age may influence their relative expression. The present study has compared ER-alpha and ER-beta expression in serial sections of human fracture callus from males (n = 19, age range 5-72 years) and females (n = 15, age range 3-86 years) by indirect immunoperoxidase. Fracture callus was used as it can be readily obtained from individuals over a wide age range and contains a variety of bone cells. Antibody specificity was confirmed by western blotting and comparison of immunoreactivity in sections of breast tumour and benign prostate hyperplasia. No gender difference in ER expression was found in bone from individuals less than 40 years old. Proliferative chondrocytes were positive for both isoforms, but few larger hypertrophic cells were immunoreactive. ER-alpha and ER-beta were co-expressed in osteoclasts, suggesting that oestrogen may act directly on these cells. Osteoblasts, osteocytes, and mesenchymal cells also expressed both isoforms. In women over 40 years of age, however, relatively fewer biopsies contained osteocytes positive for ER-alpha and ER-beta. Likewise, the proportions of osteoblasts and mesenchymal cells expressing ER-beta were reduced but ER-alpha remained unaffected. In contrast, in men over 40 years, only the proportion of biopsies containing ER-beta-positive mesenchymal cells was lower. In these older men and women, ER-alpha and ER-beta expression was retained by the small proliferative chondrocytes. These results demonstrate that gender, age, and cell type are important determinants of ER isoform expression in skeletal cells.     

CD44 expression is a feature of prostatic small cell carcinoma and distinguishes it from its mimickers

Small cell neuroendocrine carcinoma of the prostate is a rare variant of prostatic cancer that shares morphologic similarity with prostatic adenocarcinoma of Gleason 5 pattern. It has also been considered morphologically and immunohistochemically indistinguishable from small cell neuroendocrine carcinomas of other origins. CD44 is a cell-surface molecule proposed to identify cancer stem/progenitor cells in prostate cancer. We performed immunohistochemical study for CD44 expression in 11 cases of prostatic small cell neuroendocrine carcinoma and compared its patterns of expression with 73 cases of prostatic adenocarcinoma and 47 cases of small cell neuroendocrine carcinomas of other organs. Strong and diffuse membrane staining for CD44 was observed in 100% of the prostatic small cell neuroendocrine carcinomas. In conventional adenocarcinomas of the prostate, positive staining was only seen in rare, scattered tumor cells; and CD44 staining was negative in most of the small cell neuroendocrine carcinomas of nonprostate origin. The difference in CD44 expression between small cell neuroendocrine carcinomas of the prostate and those of other organs are statistically significant (P < .001). Our study demonstrates the utility of immunohistochemical staining for CD44 in distinguishing prostatic small cell neuroendocrine carcinoma from its mimickers including prostatic adenocarcinoma of Gleason 5 pattern and small cell neuroendocrine carcinomas of other organs. CD44 is the first marker that shows a high degree of tissue/organ specificity for small cell neuroendocrine carcinomas. Because CD44 is a putative marker of prostate cancer stem cells, the strong and diffuse expression of CD44 and the lack of expression of prostate luminal differentiation markers androgen receptor and prostatic specific antigen in prostatic small cell neuroendocrine carcinomas suggest that the tumor cells may retain cancer stem cell features.     

Preoperative prediction of Gleason grade in radical prostatectomy specimens: the influence of different Gleason grades from multiple positive biopsy sites.

The Gleason score of prostate adenocarcinomas is an important preoperative predictor of cancer behavior, and is used to help guide treatment. In the setting of more than two positive biopsy sites, pathologists usually grade the tumor at each site separately, and the Gleason score may differ from each positive site. This study seeks to determine if the highest Gleason score in all biopsy sites, or the Gleason score in the site with the highest tumor volume on the needle biopsy is the best predictor of final Gleason score in the radical prostatectomy specimens. Various preoperative biopsy findings were analyzed. All 151 patients had at least two positive biopsy sites and underwent radical prostatectomy. Primary and secondary Gleason pattern grades were assigned for each positive biopsy site. The tumor volume in the needle biopsy site was defined by the percentage of areas of biopsy cores involved by cancer. The radical prostatectomy specimens were completely embedded and processed in the whole-mount method. The Gleason score from both the biopsy site with the highest Gleason score and the biopsy site with the highest tumor volume on the needle biopsy correlated equally well with final Gleason score at radical prostatectomy (Spearman correlation coefficient =0.54 for both, P<0.001). The Gleason score from both the biopsy site with the highest Gleason score and the biopsy site with the highest tumor volume on the needle biopsy also correlated with primary Gleason pattern grade at radical prostatectomy (Spearman correlation coefficient =0.53 for both, P<0.001). Secondary Gleason pattern grade from the biopsy site with the highest tumor volume on the needle biopsy correlated with secondary Gleason pattern grade at radical prostatectomy slightly better than those from the biopsy site with the highest Gleason score (Spearman correlation coefficient, 0.32 vs 0.24; both P<0.001). Our data indicate that the highest Gleason score from all sites and the Gleason score from the site with the highest tumor volume on the needle biopsy are equally and significantly predictive of final Gleason score on radical prostatectomy. Both methods of prediction are significantly predictive of primary and secondary Gleason pattern grade on radical prostatectomy. We recommend that the highest Gleason score from all positive biopsy sites should be used when assigning an initial score using needle biopsies.     

Gleason grading of prostate cancer: level of concordance between pathologists at the University Hospital of the West Indies

Our aim was to study the level of interobserver concordance in the Gleason scores of prostate needle biopsy specimens reported at 1 institution. A retrospective review of all prostate needle biopsy specimens in which a diagnosis of adenocarcinoma was made during the year 2000 was conducted. Parameters evaluated included the Gleason score, Gleason grades identified, the percentage of Gleason grades 4 and 5, and the percentage of tumor in the biopsy specimen. Our results demonstrated a 60% overall concordance in consensus Gleason scores, which increased to 80% when considered in groups of a Gleason score of less than 7 vs 7 or more. The greatest discordance seemed to be in distinguishing Gleason score 6 from 7 and was more frequent among biopsy specimens with lower tumor volumes, particularly among those with less than 30% involvement. A small percentage of Gleason grade 4 pattern might predict disagreement as well. Strategies for improving accuracy of Gleason score 7 should be devised, and consensus diagnosis for biopsy specimens that demonstrate a low percentage of tumor volume is recommended.     

Anti-thrombin is expressed in the benign prostatic epithelium and in prostate cancer and is capable of forming complexes with prostate-specific antigen and human glandular kallikrein 2

Anti-thrombin, a member of the serpin family and an inhibitor of thrombin and blood coagulation factor Xa, was recently shown to inhibit angiogenesis and tumor growth. In the present study, we examined the expression of anti-thrombin in benign and malignant prostate gland. Using immunohistochemistry, anti-thrombin was found in prostate epithelium and stroma cells. Tissue microarrays of tumors (n = 112) and three different prostate cancer cell lines (PC-3, LNCaP, and DU-145) were all positive for anti-thrombin. Abundant expression in a population of prostatic tumor cells was further evidenced by in situ hybridization experiments. The immunostaining for anti-thrombin was confined to the cytoplasm, was most intense in Gleason grade 3 tumors, and in part overlapped with that of prostate-specific antigen. Western blotting of benign and malignant tissue homogenates revealed a predominant 58-kd anti-thrombin immunoreactive component. In vitro, anti-thrombin formed complexes more readily with human kallikrein 2, particularly in the presence of heparin, and less efficiently with prostate-specific antigen. Both complexes could be recognized by polyclonal and monoclonal IgGs against anti-thrombin. We conclude that anti-thrombin is widely expressed in prostate cancer but is gradually lost in tumors of high Gleason grade. Anti-thrombin may act as a local anti-angiogenic factor, the effect of which is partially lost in poorly differentiated prostatic tumors.     

Reduced 15-lipoxygenase-2 immunostaining in prostate adenocarcinoma: correlation with grade and expression in high-grade prostatic intraepithelial neoplasia

Arachidonic acid (AA) metabolites are implicated in the oncogenesis of several tumors, including prostate cancer. 15-Lipoxygenase-2 (15-LOX-2) is a novel AA-metabolizing enzyme with a limited tissue distribution, which includes prostate, lung, skin, and cornea. Previous studies have shown that 15-LOX-2 is present in benign prostate secretory cells and reduced in prostate adenocarcinoma and that production of the 15-LOX-2 metabolite 15S-hydroxyeicosatetraenoic acid is reduced in malignant compared with benign prostate. The objective of this study was to determine the frequency with which 15-LOX-2 immunostaining is reduced in prostate carcinoma and to correlate reduced expression with tumor differentiation (grade) and other pathologic parameters in radical prostatectomy specimens. Paraffin immunoperoxidase with a polyclonal antibody specific for 15-LOX-2 was performed on tumors and benign portions from 70 cases, and the percentage of tumor immunostaining for 15-LOX-2 was assessed. Whereas uniform 15-LOX-2 immunostaining was observed in secretory cells of benign glands, it was markedly reduced or absent in most adenocarcinomas: 23 of 70 tumors showed completely absent 15-LOX-2 immunostaining, and 45 of 70 cases showed negative immunostaining in more than 50% of the tumor. The extent of reduced 15-LOX-2 immunostaining correlated with tumor differentiation, with retained expression particularly in Gleason score 5 tumors versus a significant reduction of 15-LOX-2 in higher-grade tumors (mean +/- SD tumor 15-LOX-2 positive: Gleason score 5 = 67%+/-30%, Gleason score 6 = 16%+/-30%, Gleason score 7 = 23%+/-28%, Gleason score > or =8 = 41%+/-46%). In 16 cases with multifocal tumors or different foci of the same tumor with different grades, the higher-grade foci had significantly reduced 15-LOX-2 expression compared with the lower-grade foci. In peripheral zone tumors without complete loss of 15-LOX-2 expression, there was a significant inverse relationship between 15-LOX-2 immunostaining and tumor volume. There was not a significant correlation between 15-LOX-2 immunostaining and serum PSA or pathologic stage. In a subset of 27 cases, 15-LOX-2 expression in high-grade prostatic intraepithelial neoplasia (HGPIN) glands was significantly reduced compared with benign glands. These data show that in contrast to the uniform expression of 15-LOX-2 in differentiated secretory cells of benign prostate, reduced 15-LOX-2 is a common alteration in prostate carcinoma, and this correlates with tumor cell differentiation. That reduced expression is seen in HGPIN suggests that this may be an early alteration in carcinoma development.     

Foamy gland adenocarcinoma of the prostate: incidence, Gleason grade, and early clinical outcome

Foamy gland carcinoma is a variant of prostatic acinar adenocarcinoma characterized by abundant foamy cytoplasm and often pyknotic nuclei. Limited data exist regarding outcome and the clinicopathologic attributes of this variant. We screened 477 radical prostatectomies for foamy gland carcinoma to determine the incidence, amount, and Gleason grade/score of foamy gland carcinoma within the prostate. Time until prostate-specific antigen biochemical recurrence after radical prostatectomy was compared for both foamy and control/nonfoamy cases. For validation of incidence, Gleason grade, and pathologic stage, a second series of 100 consecutive radical prostatectomies was screened for foamy gland carcinoma. Foamy gland carcinoma was found in 69 (14.5%) of 477 cases. The median Gleason score of the foamy component was 7, which was not significantly different from the Gleason score of the nonfoamy component within those cases or the 408 nonfoamy cases. The most common Gleason score was 7 (44/69). There was no difference between foamy gland and nonfoamy gland cases in recurrence rate (23% versus 22%) or the average time to prostate-specific antigen recurrence (130 versus 151 months). In the second series, foamy gland carcinoma was found in 23% of cases and had a median Gleason score of 7; and the most common Gleason score was 7 (11/23). Foamy gland carcinoma exists in a significant subset of prostatic carcinomas. This variant does not appear to harbor a different prognosis compared with usual acinar adenocarcinoma, but diagnostic recognition of foamy gland carcinoma is important because there is a Gleason grade 4 element in the majority of cases.     

前列腺癌8号染色体改变与Gleason评分之间的相关性

目的探索前列腺癌8号染色体数目增加及c-myc基因和脂蛋白脂酶（LPL）基因状态和发生频率,分析8号染色体改变与前列腺癌Gleason评分之间的相关性及其在前列腺癌发生发展中的作用。方法采用ProVysion^TM三色探针组合,以荧光原位杂交（FISH）方法检测34例未经临床治疗的前列腺癌穿刺组织石蜡切片标本的8号染色体改变,其中包括Gleason评分5分者1例,6分者10例,7分者14例,8分者4例,9分者5例,并进行8号染色体各种异常之间及其与前列腺癌Gleason评分级别之间的关联性分析。结果8号染色体增加为17／34（50％）,c-myc基因拷贝数增加为21／34（61．8％）,LPL单体为15／34（44．1％）,c-myc基因扩增为23／34（67．6％）,LPL基因缺失为21／34（61．8％）,同时具有LPL基因缺失和c-myc基因扩增为16／34（47．1％）,至少有其中一种遗传学异常者为29／34（85．3％）。8号染色体增加与Gleason评分级别增高呈明显的正相关关系（P=0．0006）;c-myc基因拷贝数增加与Gleason评分级别增高呈正相关关系（P=0．0035）;LPL缺失与Gleason评分级别增高呈负相关关系（P=0．0383）;调整年龄后,除了上述三个变量与Gleason评分级别的相关关系仍然存在以外,c-myc基因扩增与Gleason评分级别增高也呈现正相关关系（P=0．0462）。结论8号染色体数目增加、c-myc基因拷贝数增加、c-myc基因扩增和LPL基因丢失都与Gleason评分级别有关,c-myc基因扩增同时伴有LPL基因缺失也是前列腺癌的遗传学特征之一,提示8号染色体异常可能与前列腺癌的发生和进展有关。     

Expression of oestrogen receptor-alpha and -beta in ovarian endometriomata.

The contribution of oestrogen receptor (ER) isoforms, ER-alpha and ER-beta, in oestrogen-dependent development and growth of ovarian endometriomata, is unknown. Therefore, we examined the expression of ER-alpha and ER-beta in ovarian endometriomata and normal uterine endometrium. ER-alpha and ER-beta were shown to be dominantly expressed in the nuclei of the epithelial lining cells of ovarian endometrioma and of the glandular cells of normal uterine endometrium. ER-beta was expressed at a much lower level than ER-alpha in the glandular cells of normal uterine endometrium, while ER-beta was expressed at a slightly lower level than ER-alpha in the epithelial lining cells of ovarian endometrioma. In normal uterine endometrium, ER-beta mRNA was expressed at a much lower level than ER-alpha mRNA, and the expression pattern of ER-beta mRNA during the menstrual cycle was similar to that of ER-alpha mRNA. On the other hand, ER-beta mRNA expression was significantly higher and over a much greater range in ovarian endometriomata (P < 0.05) than in normal uterine endometrium during the menstrual cycle, while ER-alpha mRNA expression was relatively lower and more random. Therefore, in ovarian endometriomata, oestrogen action via ER-alpha cascades seems to be partially damaged, as the expression of ER-alpha mRNA does not respond to endocrinological alterations during the menstrual cycle, while the relative over-expression of ER-beta might be related to a unique oestrogen-dependent growth and spreading of ovarian endometriomata.     

N-Cadherin Expression in Human Prostate Carcinoma Cell Lines : An Epithelial-Mesenchymal Transformation Mediating Adhesion with Stromal Cells

In human prostate adenocarcinoma, an association between loss of E-cadherin, increased Gleason score, and extracapsular dissemination has been observed. Further characterization of the E-cadherin/catenin phenotype of human prostate carcinoma cell lines showed loss of E-cadherin and expression of N-cadherin in poorly differentiated prostate carcinoma cell lines (PC-3N derived from PC-3, PC-3, and JCA1). We showed that N-cadherin is concentrated at sites of cell-cell contact in PC-3N cellular extensions. N-cadherin was also expressed in prostate stromal fibroblasts both in vitro and in prostate tissue. Co-cultures of prostate stromal fibroblasts and PC-3N cells showed the immunolocalization of N-cadherin in intercellular contacts. In addition, the isoform expression of the cadherin binding protein p120(ctn) differed in relation to the expression of E- versus N-cadherin by the prostate carcinoma cell lines. The p100 isoform was more highly expressed in E-cadherin-positive carcinoma cell lines, whereas p120 was predominantly expressed only in N-cadherin-positive prostate carcinoma cell lines and prostate stromal fibroblasts. The N-cadherin-positive carcinoma cell line, PC-3N, displayed aggressive invasion into the surface of the diaphragm muscle after intraperitoneal injection of SCID mice. The gain of N-cadherin and loss of E-cadherin by invasive prostate carcinoma cell lines suggests a progression from an epithelial to a mesenchymal phenotype, which may allow for their interaction with surrounding stromal fibroblasts and facilitate metastasis.