Glycodelin reduces breast cancer xenograft growthin vivo

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

Altered glycosylation of glycodelin in endometrial carcinoma

Glycodelin is a major glycoprotein expressed in reproductive tissues, like secretory and decidualized endometrium. It has several reproduction related functions that are dependent on specific glycosylation, but it has also been found to drive differentiation of endometrial carcinoma cells toward a less malignant phenotype. Here we aimed to elucidate whether the glycosylation and function of glycodelin is altered in endometrial carcinoma as compared with a normal endometrium. We carried out glycan structure analysis of glycodelin expressed in HEC-1B human endometrial carcinoma cells (HEC-1B Gd) by mass spectrometry glycomics strategies. Glycans of HEC-1B Gd were found to comprise a typical mixture of high-mannose, hybrid, and complex-type N-glycans, often containing undecorated LacNAc (Galβ1-4GlcNAc) antennae. However, several differences, as compared with previously reported glycan structures of normal human decidualized endometrium-derived glycodelin isoform, glycodelin-A (GdA), were also found. These included a lower level of sialylation and more abundant poly-LacNAc antennae, some of which are fucosylated. This allowed us to select lectins that showed different binding to these classes of glycodelin. Despite the differences in glycosylation between HEC-1B Gd and GdA, both showed similar inhibitory activity on trophoblast cell invasion and peripheral blood mononuclear cell proliferation. For the detection of cancer associated glycodelin, we established a novel in situ proximity-ligation based histochemical staining method using a specific glycodelin antibody and UEAI lectin. We found that the UEAI reactive glycodelin was abundant in endometrial carcinoma, but virtually absent in normal endometrial tissue even when glycodelin was strongly expressed. In conclusion, we established a histochemical staining method for the detection of endometrial carcinoma-associated glycodelin and showed that this specific glycodelin is exclusively expressed in cancer, not in normal endometrium. Similar methods can be used for studies of other glycoproteins.

The Roles of Glycodelin in Cancer Development and Progression

Glycodelin is a kind of glycoprotein expressed in secretory endometrium, pregnancy deciduas, and amniotic fluid originally, which is vital for the maintenance of normal human reproductive activities. Recent researches have reported that glycodelin is specifically expressed in various malignancies, including female-specific cancers such as endometrial cancer, ovarian cancer and breast cancer, and non-gender specific cancers including lung cancer, and colon cancer, and glycodelin expression correlates with the diagnosis and prognosis of cancer patients. This review focuses on the expression of glycodelin in different cancers and its role in cancer development and progression. Glycodelin possesses the abilities to regulate cancer cell proliferation, differentiation, and invasion, promote cancer angiogenesis, and modulate the differentiation and function of immune cells including T cells, dendritic cells, monocyte-macrophages, natural killer cells and B cells participating in cancer development. The expression of glycodelin can be regulated by stromal cells, lysophosphatidic acid, histone deacetylase inhibitors, and relaxin. In summary, glycodelin is a promising biomarker for the diagnosis and prognosis of cancer patients, and depending on its distinct immunoregulatory effects, glycodelin can be a prospective target for cancer immunotherapy.

Repressed PKCδ activation in glycodelin-expressing cells mediates resistance to phorbol ester and TGFβ

Glycodelin is a glycoprotein mainly expressed in well-differentiated epithelial cells in reproductive tissues. In normal secretory endometrium, the expression of glycodelin is abundant and regulated by progesterone. In hormone-related cancers glycodelin expression is associated with well-differentiated tumors. We have previously found that glycodelin drives epithelial differentiation of HEC-1B endometrial adenocarcinoma cells, resulting in reduced tumor growth in a preclinical mouse model. Here we show that glycodelin-transfected HEC-1B cells have repressed protein kinase C delta (PKCδ) activation, likely due to downregulation of PDK1, and are resistant to phenotypic change and enhanced migration induced by phorbol 12-myristate 13-acetate (PMA). In control cells, which do not express glycodelin, the effects of PMA were abolished by using PKCδ and PDK1 inhibitors, and knockdown of PKCδ, MEK1 and 2, or ERK1 and 2 by siRNAs. Similarly, transforming growth factor β (TGFβ)-induced phenotypic change was only seen in control cells, not in glycodelin-producing cells, and it was mediated by PKCδ. Taken together, these results strongly suggest that PKCδ, via MAPK pathway, is involved in the glycodelin-driven cell differentiation rendering the cells resistant to stimulation by PMA and TGFβ.

PIAS1 regulates breast tumorigenesis through selective epigenetic gene silencing

Epigenetic gene silencing by histone modifications and DNA methylation is essential for cancer development. The molecular mechanism that promotes selective epigenetic changes during tumorigenesis is not understood. We report here that the PIAS1 SUMO ligase is involved in the progression of breast tumorigenesis. Elevated PIAS1 expression was observed in breast tumor samples. PIAS1 knockdown in breast cancer cells reduced the subpopulation of tumor-initiating cells, and inhibited breast tumor growth in vivo. PIAS1 acts by delineating histone modifications and DNA methylation to silence the expression of a subset of clinically relevant genes, including breast cancer DNA methylation signature genes such as cyclin D2 and estrogen receptor, and breast tumor suppressor WNT5A. Our studies identify a novel epigenetic mechanism that regulates breast tumorigenesis through selective gene silencing.

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

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.

Optimization and establishment of RNA interference-mediated knockdown of the progestagen-associated endometrial protein gene in human metastatic melanoma cell lines

Progestagen‑associated endometrial protein (PAEP), also termed glycodelin, is a 28‑kDa glycoprotein of the lipocalin superfamily that is expressed in a variety of tumors, including gynecological tumors, lung cancer and melanoma. To determine the biological functions of the PAEP gene in tumor development and progression, the production of transient and stable PAEP knockdown cell models is required. In the present study, RNA interference technology was used to silence PAEP gene expression in melanoma and transfection was screened for and the conditions were optimized using fluorescence microscopy, flow cytometry, qPCR and western blot analysis. The results of the present study showed that the transient transfection of melanoma cells with 100 nmol/l PAEP siRNA or lentiviral PAEP small hairpin RNA (shRNA) [multiplicity of infection (MOI), 100 pfu/cell] efficiently knocked down target gene expression. To establish stable PAEP knockdown cell lines, melanoma cells were infected with a low MOI (10 pfu/cell) of lentiviral particles expressing PAEP shRNA. Following puromycin screening, the PAEP gene knockdown efficiency was demonstrated to be >80% in 624‑Mel and 624.38‑Mel cell lines, which was validated by western blot analysis. Therefore, melanoma cell lines with stable knockdown of PAEP were successfully established and may be used as effective cell models to study the biological functions of the PAEP gene in melanoma.

Immunolocalization of glycodelin in human adenocarcinoma of the lung, squamous cell carcinoma of the lung and lung metastases of colonic adenocarcinoma

Glycodelin (Gd), which is localized in cells of bronchial epithelium, type II pneumocytes and alveolar macrophages in rats and humans, plays an important role in the pulmonary immune response in asthmatic inflammation. In this study, sections of paraffin-embedded tumor adjacent lung tissue and sections of adenocarcinoma of the lung, squamous cell carcinoma of the lung and metastases of colonic adenocarcinoma were investigated for the distribution and expression of Gd using a polyclonal anti-Gd antibody. Glycodelin protein is located in the cytoplasm of bronchial epithelial cells, pneumocytes and alveolar macrophages. Furthermore, Gd is expressed in adenocarcinoma and squamous cell carcinoma of the lung as well as in lung metastases of colonic adenocarcinoma. Densitometric analyses showed a significantly increased expression of glycodelin protein in cancer tissue compared to tumor adjacent lung tissue. The Gd protein level was 1.7-2.6-fold increased in lung carcinoma compared to tumor adjacent lung tissue. The Gd protein level did not differ from each other between the investigated types of cancer tissue. Because these data validate the recent findings of Gd mRNA expression, it may be concluded that glycodelin plays an important role in the pathogenesis of lung cancer and lung metastases.

Human amniotic glycodelin actively regulates changes in β-catenin immunoreactivity in cultured human umbilical vein endothelial cells (HUVEC)

OBJECTIVE

Assessment of the capacity of Glycodelin A (GdA) to modulate the aggregation of cultured human umbilical vein endothelial cells.

METHODS

Highly purified Glycodelin A (GdA) from late first trimester amniotic fluid has been added to cultured cells and its biological activity has been observed with immunofluorescent staining of β-catenin molecules.

RESULTS

GdA induces translocation of β-catenin molecules promoting cell-to-cell adhesion and formation of adherents junctions through cytoskeletal reorganization.

CONCLUSION

These data provide further mechanistic insight into the specificity of cell-to-cell adhesion, thus corroborating the role of GdA in promoting angiogenesis.

Glycodelin expression associates with differential tumour phenotype and outcome in sporadic and familial non-BRCA1/2 breast cancer patients

Glycodelin (encoded by PAEP gene) is a secreted lipocalin protein mainly expressed in reproductive tissues, but also in several tumour types. In the breast, glycodelin is expressed both in normal epithelial and cancerous tissue. To investigate the association of glycodelin with clinicopathological features of breast cancer and outcome of patients we evaluated the protein expression of glycodelin in a large series of breast tumours. Immunohistochemical analysis of tissue microarrays was used to study glycodelin expression on 399 sporadic and 436 familial non-BRCA1/2 tumours with strong family history. Gene expression analysis was used to define genes co-expressed with PAEP in sporadic and familial non-BRCA1/2 breast tumours. In the sporadic series, the glycodelin expression associated with low proliferation rate (P < 0.001), with a tendency towards well-differentiated tumours (grades 1 and 2, P = 0.012) and high cyclin D1 (P = 0.034) expression. However, in familial non-BRCA1/2 cases with strong family history glycodelin expression associated with a less favourable phenotype, i.e. positive lymph node status (P = 0.003) and HER2-positive tumours (P = 0.009). Moreover, the patients with glycodelin-positive tumours had an increased risk for distant metastases (P = 0.001) and in multivariate analysis glycodelin expression was an independent predictor of metastasis (hazard ratio (HR) = 2.22, 95% confidence interval (95% CI) = 1.22-4.03, P = 0.009) in familial non-BRCA1/2 breast cancer. Gene expression analysis further revealed different gene expression profiles correlating with the PAEP expression in the sporadic and familial non-BRCA1/2 breast cancers. Our findings suggest differential progression pathways in the sporadic and familial non-BRCA1/2 breast tumours expressing glycodelin.

Functional characterization of the progestagen-associated endometrial protein gene in human melanoma

Utilizing gene microarray profiling of melanoma samples, we have recently identified a novel gene overexpressed in both thick primary and metastatic melanomas. This gene, progestagen-associated endometrial protein (PAEP), has never before been implicated in the oncogenic processes of melanoma, with its true function in oncogenesis and tumour progression relatively unknown. Overexpression of the PAEP gene in freshly procured thick primary and metastatic melanoma samples (58%) and daughter cell lines (77%) is confirmed by quantitative RT-PCR, immunohistochemistry, Western blotting and mass spectrometric analysis. We suggest that PAEP gene overexpression is involved with melanoma tumour progression as well as an aggressive phenotype. Transfection of melanoma cells with PAEP small interfering RNA (siRNA) reveals a significant decrease in soft agar colony formation and a marked inhibition of both cell migration and cell invasion. Furthermore, we establish stable melanoma transfectants via PAEP lentiviral small hairpin RNA (shRNA), examine their growth characteristics in a murine xenograft model and reveal that tumour growth is significantly inhibited in two separate melanoma cell lines. Our data strongly implicate the PAEP gene as a tumour growth promoter with oncogenic properties and a potential therapeutic target for patients with advanced melanoma.

GATA3 inhibits breast cancer growth and pulmonary breast cancer metastasis

The loss of expression of the transcription factor GATA3 in breast tumors has been linked to aggressive tumor development and poor patient survival. In the present work, we address potential roles for GATA3 in breast tumor lung metastasis and progression. Using an aggressive breast cancer cell line, which metastasizes specifically to the lung, we show that GATA3 expression results in reduced tumor outgrowth in the mammary fat pad and lower lung metastatic burden in nude mice. Specifically, GATA3 expression inhibits breast cancer cell expansion inside the lung parenchyma. This phenotype correlates with the ability of GATA3 to negatively regulate the expression of several genes that promote breast cancer lung metastasis (ID1/-3, KRTHB1, LY6E and RARRES3). Conversely, the expression of genes encoding known inhibitors of lung metastasis (DLC1 (deleted in liver cancer 1) and PAEP (progestagen-associated endometrial protein)) is upregulated by GATA3. These data correlate with microarray data from human breast cancer patients, showing a strong correlation between high GATA3 expression and absence of metastases specifically to the lungs. We conclude that GATA3 inhibits primary breast tumor outgrowth and reduces lung metastatic burden by regulating key genes involved in metastatic breast tumor progression.