Collagen XXIII expression is associated with prostate cancer recurrence and distant metastases.

PURPOSE: We had previously identified a new transmembrane collagen, type XXIII, in metastatic rat prostate carcinoma cells. The purpose of this study was to determine the expression of collagen XXIII in human prostate cancer and investigate its relationship with disease progression. EXPERIMENTAL DESIGN: We investigated collagen XXIII expression in prostate cancer tissue and did a retrospective analysis of association with prostate-specific antigen (PSA)-defined disease recurrence. The presence of collagen XXIII in prostate cancer patient urine was also assessed before and after prostatectomy. RESULTS: Collagen XXIII protein was detected at very low levels in benign prostate tissue and was significantly increased in prostate cancer. Distant metastases exhibited significantly higher collagen XXIII levels compared with either localized prostate cancer or regional (lymph node) metastases. Patients with high collagen XXIII levels had a 2.8-fold higher risk of PSA failure with median time to failure of 8.1 months, compared with low collagen XXIII patients with a median time to failure of 5 years. Multivariate Cox regression showed that the presence of collagen XXIII was significantly associated with time to PSA recurrence, independent of other clinical variables. Collagen XXIII was also detected in prostate cancer patient urine, with reduced levels after prostatectomy, indicating potential as a noninvasive fluid biomarker. CONCLUSIONS: We present the first report demonstrating increased collagen XXIII expression in prostate cancer tissue. We show that collagen XXIII level is a significant independent predictor of PSA-defined disease recurrence, suggesting a potential role as a molecular biomarker of prostate cancer progression and metastasis.

Prevalent overexpression of prolyl isomerase Pin1 in human cancers.

Phosphorylation of proteins on serine or threonine residues preceding proline (pSer/Thr-Pro) is a major regulatory mechanism in cell proliferation and transformation. Interestingly, the pSer/Thr-Pro motifs in proteins exist in two distinct cis and trans conformations, whose conversion rate is normally reduced on phosphorylation, but is catalyzed specifically by the prolyl isomerase Pin1. Pin1 can catalytically induce conformational changes in proteins after phosphorylation, thereby having profound effects on catalytic activity, dephosphorylation, protein-protein interactions, subcellular location, and/or turnover of certain phosphorylated proteins. Recently, it has been shown that Pin1 is overexpressed in human breast cancer cell lines and cancer tissues and plays a critical role in the transformation of mammary epithelial cells by activating multiple oncogenic pathways. Furthermore, Pin1 expression is an excellent independent prognostic marker in prostate cancer. However, little is known about Pin1 expression in other human normal and cancerous tissues. In the present study, we quantified Pin1 expression in 2041 human tumor samples and 609 normal tissue samples as well as normal and transformed human cell lines. We found that Pin1 was usually expressed at very low levels in most normal tissues and its expression was normally associated with cell proliferation, with high Pin1 levels being found only in a few cell types. However, Pin1 was strikingly overexpressed in many different human cancers. Most tumors (38 of 60 tumor types) have Pin1 overexpression in more than 10% of the cases, as compared with the corresponding normal controls, which included prostate, lung, ovary, cervical, brain tumors, and melanoma. Consistent with these findings, Pin1 expression in human cancer cell lines was also higher than that in the normal cell lines examined. These results indicate that Pin1 overexpression is a prevalent and specific event in human cancers. Given previous findings that Pin1 expression is an excellent prognostic marker in prostate cancer and that inhibition of Pin1 can suppress transformed phenotypes and inhibit tumor cell growth, these findings may have important implications for the pathogenesis, diagnosis, and treatment of human cancers.

The prolyl isomerase Pin1 is a novel prognostic marker in human prostate cancer.

Prostate cancer (PCa) is the most common male cancer in the United States. A major challenge that remains is to predict the clinical outcome in managing PCa patients. The prolyl isomerase Pin1 has been shown to be overexpressed in some human cancer tissues and thought to be an important player in several oncogenic pathways. However, the relationship between Pin1 expression and clinical outcome of cancer patients has not been explored. In this study, we investigated the role of Pin1 in human PCa progression and its clinicopathological significance. Immunohistochemical assessment with affinity-purified polyclonal Pin1-specific antibodies was performed on formalin-fixed paraffin sections of tissue microarray composed of 580 radical prostatectomy specimens. As determined by visual semiquantitation and confirmed by automated image analysis quantitation, Pin1 expression was positively correlated with clinical stage. Furthermore, Cox survival analysis results indicated that patients with a higher Pin1 expression had a significantly higher probability of recurrence than their counterparts with low Pin1 expression, as defined by a serum prostate-specific antigen level of > or =0.4 ng/ml on two consecutive occasions after radical prostatectomy. In addition, patients with high Pin1 expression had almost 4 times the risk of having earlier recurrence than those with low Pin1 expression; patients with a very high level had 8.1 times the risk of an earlier recurrence than a low Pin1 expresser. Pin1 was also an excellent predictor of recurrence in the subset of patients with Gleason score 6 or 7 when analyzed separately: a patient with high Pin1 expression had 8.6 times the risk of having earlier recurrence than one with low Pin1 expression. Pin1 expression is as good as or better than currently used postoperatively available clinicopathological parameters and potentially could be used in the preoperative setting to assist in choice of treatment. Thus, this study suggests a role for Pin1 expression as a potentially excellent prognostic marker in PCa and suggests that Pin1 may also serve as a novel therapeutic target for PCa.

Type XXIII collagen, a new transmembrane collagen identified in metastatic tumor cells.

We have identified a transmembrane collagen, collagen XXIII, in rat prostate carcinoma cells. Differential display of mRNA expression in prostate carcinoma sublines with varying metastatic potential revealed overexpression of this transcript in the metastatic AT6.1 subline. cDNA cloning identified a 2733-bp transcript from AT6.1 RNA, encoding a protein of 532 amino acids, together with a 3067-bp human homologue, resulting in a 540-amino acid protein. Collagen XXIII is predicted to be a type II membrane protein consisting of an amino-terminal cytoplasmic domain, a transmembrane region, and three collagenous domains flanked by short noncollagenous domains. Collagen XXIII is a new member of the transmembrane collagen family, showing structural homology with the transmembrane collagens XIII and XXV. We present evidence that collagen XXIII is expressed as a approximately 75-kDa protein at the cell surface and that it can be cleaved by furin protease activity. Cleavage results in a approximately 60-kDa soluble protein that forms a multimeric complex and exhibits a low affinity interaction with heparin.