Prognostic significance of circulating intact and cleaved forms of urokinase plasminogen activator receptor in inoperable chemotherapy treated cholangiocarcinoma patients

https://doi.org/10.1016/j.clinbiochem.2014.01.030Get rights and content

Highlights

  • uPAR is investigated as a prognostic marker in inoperable cholangiocarcinoma.

  • Two independent cohorts have been evaluated.

  • uPAR(I-III) + (II-III) is of prognostic significance in inoperable cholangiocarcinomas.

Abstract

Background

High levels of intact and cleaved forms of the urokinase-type plasminogen activator receptor (uPAR) in both tissue and blood are associated with poor survival in several cancer diseases. The prognostic significance of uPAR in cholangiocarcinoma is unknown. The aims of this study were to determine if pre-treatment serum levels of uPAR forms and a decrease in levels during chemotherapy are predictive of survival in patients with inoperable cholangiocarcinoma.

Design and methods

Patients with inoperable cholangiocarcinoma were consecutively included in the training set (n = 108). A test set included patients from a different hospital using similar treatment guidelines (n = 60). Serum levels of the different uPAR forms were determined using time-resolved fluorescence immunoassays (TR-FIA). The Cox proportional hazards model was used for the uni- and multivariate survival analyses.

Results

Baseline level of uPAR(I–III) + uPAR(II–III) was an independent predictor of survival (HR = 2.08, 95% CI:1.46–2.97, p < 0.0001). Applying the linear predictor from the training set to the test set, it was validated that uPAR(I–III) + uPAR(II–III) predicted overall survival (p = 0.049). A high level of uPAR(I–III) + uPAR(II–III) after 2 cycles of chemotherapy was associated with poor survival (HR = 1.79, 95% CI:1.08–2.97, p = 0.023, n = 57). This predictor, however, was not significant in the test set (p = 0.21, 26 events in 27 patients).

Conclusion

The baseline level of uPAR(I–III) + uPAR(II–III) is a predictor of survival in inoperable cholangiocarcinoma patients.

Introduction

Surgery is the only curative treatment option in cholangiocarcinoma. Unfortunately most patients are diagnosed with advanced cholangiocarcinomas when curable resection is no longer possible. As a consequence the prognosis is poor with a 5-year survival rate of less than 5% [26]. In 2010, a large randomized trial including unresectable cholangiocarcinoma patients showed that combination chemotherapy prolongs survival [28]. Unfortunately, far from all patients respond to chemotherapy and a major clinical challenge is to identify the patients who will actually benefit from treatment. In order to accomplish this, predictive and prognostic biomarkers are required. Hence, the prognostic significance of several markers in serum from patients with cholangiocarcinomas has been investigated, but no single marker has so far been proven clinical useful [18].

The components of the plasminogen activation system have been demonstrated to be strong prognostic markers in several cancers, when measured in both tumor tissue and in blood [7]. The plasminogen activation system components, the urokinase-type plasminogen activator (uPA) and its receptor (uPAR), are both essential for pericellular proteolysis which is required for tissue remodeling during both normal physiological conditions such as wound healing [17] and initiation of angiogenesis [14], as well as during cancer invasion [8].

uPAR is a three-domain receptor attached to the cell membrane by a glycolipid-anchor located on domain III [22]. Intact uPAR(I–III) can be cleaved by uPA, releasing domain I (uPAR (I)), while leaving uPAR(II–III) on the cell surface. Both of the glycolipid-anchored uPAR forms (uPAR(II–III) and uPAR(I–III)) can be shed from the cell membrane [17], resulting in three soluble uPAR forms (uPAR(I–III) and uPAR(II–III) as well as uPAR(I)) detectable in the blood. The levels of the cleaved forms may reflect the catalytic activity of uPA [11]. Interestingly, the cleaved soluble uPAR forms have been demonstrated to be independent prognostic markers in various types of cancer, such as colorectal [16], [27], lung [3], prostate [2] and ovarian cancer [10].

Currently, no published data exists on the prognostic significance of circulating uPAR forms in cholangiocarcinoma except from our own previously published study with only nine cholangiocarcinoma patients included [25].

In the present study, we explore whether the levels of different uPAR forms in serum measured before and during chemotherapy predict survival in two cohorts of patients with inoperable cholangiocarcinoma treated according to the same treatment guidelines at two different hospitals.

Section snippets

Design

This a retrospective study, performed in accordance with the REMARK-guidelines [6], [19] reporting all items (1–20) on the REMARK checklist.

Training set

Consecutive patients with inoperable cholangiocarcinoma treated at Rigshospitalet, Copenhagen, from February 2004 to February 2011 were identified (n = 108). Follow-up continued until March 2013.

In the entire study period, a single chemotherapy regimen was used exclusively as standard therapy in bile duct cancer. Hence, it was possible to identify all

Patient and baseline characteristics

Of 170 patients registered as receiving chemotherapy, 108 patients had received chemotherapy for inoperable cholangiocarcinoma and had a baseline (i.e. at the start of treatment) serum sample available for analysis (Supplementary Fig. 1). Serum samples collected after two cycles of treatment were available from 59 patients and 48 of these also had a baseline serum sample available. The number of deaths was 102 of the 108 patients. Patients' baseline-characteristics are presented in Table 1.

Discussion

We have tested two hypotheses: 1) pre-therapeutic levels of the different uPAR forms in serum have prognostic significance and 2) a decrease in the levels of any of the uPAR forms after two cycles of chemotherapy is predictive of survival in inoperable cholangiocarcinoma.

We have demonstrated that elevated serum levels at baseline of all three forms of soluble uPAR are predictive of a poor survival in inoperable cholangiocarcinoma patients. In a test set we were able to confirm that uPAR(I–III) + 

Conflicts of interest

None of the authors have conflicts of interest to declare.

Author contributions

MG, MS and GHH designed the study.

MG, ML, TT, UL, MS, LHJ and IKL acquired the data presented in this article.

IJC and MG carried out the statistical analysis.

MG analyzed and interpreted data and drafted the manuscript.

MS, GHH, IJC and IKL performed critical revision of the manuscript for important intellectual content.

GHH and MS supervised the study.

All authors read, revised and finally approved the final manuscript.

Funding

MG is funded by the Oncological Research Foundation, Dept. of Oncology, Rigshospitalet, Denmark.

Acknowledgments

The excellent technical assistance of Ruth Petersson is gratefully acknowledged as well as the useful advices from Professor Nils Brünner.

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