Prognostic value of tumour endothelial markers in patients with endometrial cancer

Abstract

Endometrial cancer is one of the more frequent and most lethal gynaecological cancer types. Since it occurs more frequently in elderly and overweight patients, a pre-operative staging method would be beneficial. The growth of solid neoplasms is always accompanied by neovascularisation. Tumour endothelial markers (TEMs) are a group of recently described endothelial cell surface markers that appear to be specific to neoplastic tissue. This study aimed to investigate the potential usefulness of TEM assessment in the endometrium by comparing the transcriptional expression of TEMs in the normal endometrium with endometroid adenocarcinoma tissue. Tissues were lysed and the RNA was extracted, assessed and reverse transcribed in one batch. Real-time quantitative PCR was performed for TEM-1, -2, -6, -7, -7r and -8. GAPDH, β-actin and ribosomal protein L13A (RPL13A) were used as control genes. TEM-8 showed the highest expression level in all of the groups. TEM-1 showed higher expression levels in the normal endometrium than in the tumour tissues. For the remaining TEMs, we found a higher expression in the cancer samples than in the normal endometria. Statistical significance of this difference was achieved for TEM-1, -2 and-7. No clear correlation was noted between the tumour stage and the level of TEM-1, -6 and -8 expression. Apart from TEM-6, the highest expression in FIGO I cancer stages was noted in the remaining TEMs. Our results showed that for most of these tumour endothelial markers, gene expression was slightly higher in the endometrial carcinoma tissue samples than in the endometrium of normal cycling women. However, with the possible exception of TEM-8 and -6, absolute expression levels were generally low, indicating that most TEMs may only be specifically expressed in a restricted number of cancer types (e.g., colorectal). Therefore, TEMs may not be useful in the context of endometrial cancer.

Figure 1

Gene expression levels of tumour endothelial markers (TEMs), glycodelin (PP14) and matrix metalloproteinase-2 (MMP-2) in healthy endometrial tissue (light bars, n=8) and endometrial carcinoma (dark bars, n=10). Values are expressed as mean ± SD in Ct (i.e., relative to the copy number, in powers of 2) and normalised to the means for GAPDH, β-actin and ribosomal protein L13A (reference genes). The base line (-16.7) corresponds to the absence of the QPCR signal for the reference genes after 40 cycles. ^*Statistically significant differences (P<0.05, Student’s t-test).