Immunosuppressive Glycodelin A is an independent marker for poor prognosis in endometrial cancer

Abstract

Background: Knowledge on immunosuppressive factors in the pathogenesis of endometrial cancer is scarce. The aim of this study was to assess Glycodelin (Gd) and its immunosuppressive isoform Glycodelin A (GdA) in endometrial cancer tissue and to analyze its impact on clinical and pathological features and patient outcome.

Methods: 292 patients diagnosed and treated for endometrial cancer were included. Patient characteristics, histology and follow-up data were available. Gd and GdA was determined by immunohistochemistry and in situ hybridization was performed for Gd mRNA.

Results: Endometrial cancer shows intermediate (52.2%) or high (20.6%) expression for Gd in 72.8%, and GdA in 71.6% (intermediate 62.6%, high 9.0%) of all cases. The glycosylation dependent staining of GdA is tumour specific and correlates with the peptide-specific Gd staining though neither of the two is associated with estrogen receptor, progesterone receptor or clinic-pathological features. Also Gd protein positively correlates with Gd mRNA as quantified by in situ hybridization. Gd positive cases have a favourable prognosis (p = 0.039), while GdA positive patients have a poor outcome (p = 0.003). Cox-regression analysis proofed GdA to be an independent prognostic marker for patient survival (p = 0.002), besides tumour stage, grade and the concomitant diagnosis of hypertension.

Conclusion: Gd and GdA are commonly expressed in endometrial cancer tissue and seem to be of relevance in tumourigenesis. They differ not only in glycosylation but also in their biological activity, since only GdA holds prognostic significance for a poor overall survival in endometrial cancer patients. This finding might be explained by GdAs immunosuppressive capacity.

Figure 1

Gd mRNA (PAEP) was detected in endometrial cancer tissue by in situ hybridization. Representative microphotographs of Glycodelin (Gd) mRNA (PAEP, progestagen-associated endometrial protein) as detected by in situ hybridization in different histological subtypes (A-C) of endometrial cancer tissue are shown. Samples were treated with an antisense riboprobe recognizing Gd mRNA (A-C) or with the complementary sense riboprobe as a negative control (insert in A), respectively. Mean optical density of Gd mRNA signal has been quantified in a semi-automated manner and Gd positive pixels were determined by KSRun software. Gd mRNA positivity in dependence of histological subtype (D), FIGO stage (E) and grading (F) is illustrated using box plot diagrams. Scale bar in C represents 100 μm and refers to A-C.

Figure 2

Glycodelin and Glycodelin A protein was detected in endometrial cancer tissue by immunohistochemistry. Representative microphotographs of Glycodelin (Gd, A-C) and its immunosuppressice glyco-variant Glycodelin A (GdA, D-F) as detected by immunohistochemistry in different histological subtypes of endometrial cancer tissue are shown. Pan-Glycodelin as well as its immunosuppressive glyco-variant Glycodelin A was found to be predominantly produced by epithelial components of endometrial carcinomas. Scale bars in F represent 100 μm and refer to A-F.

Figure 3

Glycodelin as well as its immunosuppressive glyco-variant Glycodelin A protein was analysed and quantified in endometrial cancer tissue. Quantification of Glycodelin (Gd; A, C, E) and its immunosuppressive glyco-variant Glycodelin A (GdA; B, D, F) by immunohistochemistry is shown. Gd/GdA was visualized in endometrial carcinoma tissue of different histological subtypes (A, B), FIGO stages (C, D) or tumour grades (E, F). Gd and GdA were detected by immuno-histochemistry and quantified employing an immunoreactive score (IRS) ranging from 0 (lowest) to 12 (highest). Significant differences (p < 0.05) as determined by Mann–Whitney Test are indicated by #.

Figure 4

Kaplan Meier survival analyses were performed for Glycodelin and Glycodelin A in endometrial cancer patients. Overall survival of patients with low, intermediate and high Glycodelin A (A) and Glycodelin (B) protein expression as detected by immunohistochemistry is shown.