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EpCAM is overexpressed in local and metastatic prostate cancer, suppressed by chemotherapy and modulated by MET-associated miRNA-200c/205.

Massoner P, Thomm T, Mack B, Untergasser G, Martowicz A, Bobowski K, Klocker H, Gires O, Puhr M - Br. J. Cancer (2014)

Bottom Line: Oppositely, re-induction of the epithelial phenotype through miRNAs miR-200c and miR-205, two inducers of mesenchymal-to-epithelial transition (MET), led to re-induction of EpCAM in chemoresistant cells.Furthermore, we prove that EpCAM cleavage, the first step of EpCAM signalling takes place in prostate cancer cells but in contrast to other cancer entities, EpCAM has no measurable impact on the proliferative behaviour of prostate cells, in vitro.In conclusion, our data confirm that EpCAM overexpression is an early event during prostate cancer progression.

View Article: PubMed Central - PubMed

Affiliation: 1] Experimental Urology, Department of Urology, Innsbruck Medical University, Innsbruck, Austria [2] Department of Otorhinolaryngology, Head and Neck Surgery, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT

Background: Expression of epithelial cell adhesion molecule (EpCAM) is deregulated in epithelial malignancies. Beside its role in cell adhesion, EpCAM acts as signalling molecule with tumour-promoting functions. Thus, EpCAM is part of the molecular network of oncogenic receptors and considered an interesting therapeutic target.

Methods: Here, we thoroughly characterised EpCAM expression on mRNA and protein level in comprehensive tissue studies including non-cancerous prostate specimens, primary tumours of different grades and stages, metastatic lesions, and therapy-treated tumour specimens, as well as in prostate cancer cell lines.

Results: Epithelial cell adhesion molecule was overexpressed at mRNA and at protein level in prostate cancer tissues and cell lines. Altered EpCAM expression was an early event in prostate carcinogenesis with an upregulation in low-grade cancers and further induction in high-grade tumours and metastatic lesions. Interestingly, EpCAM was repressed upon induction of epithelial-to-mesenchymal transition (EMT) following chemotherapeutic treatment with docetaxel. Oppositely, re-induction of the epithelial phenotype through miRNAs miR-200c and miR-205, two inducers of mesenchymal-to-epithelial transition (MET), led to re-induction of EpCAM in chemoresistant cells. Furthermore, we prove that EpCAM cleavage, the first step of EpCAM signalling takes place in prostate cancer cells but in contrast to other cancer entities, EpCAM has no measurable impact on the proliferative behaviour of prostate cells, in vitro.

Conclusions: In conclusion, our data confirm that EpCAM overexpression is an early event during prostate cancer progression. Epithelial cell adhesion molecule displays a dynamic, heterogeneous expression and associates with epithelial cells rather than mesenchymal, chemoresistant cells along with processes of EMT and MET.

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EpCAM overexpression in PCa prevails at protein level. EpCAM mRNA expression levels were determined by qRT-PCR (A), EpCAM protein levels by immunoblot (B), and EpCAM cell surface protein levels by extracellular immunostaining and flow cytometry (C and D) in Du145, DuCaP, LNCaP, PC3, EP156T, and RWPE-1 cells.
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fig3: EpCAM overexpression in PCa prevails at protein level. EpCAM mRNA expression levels were determined by qRT-PCR (A), EpCAM protein levels by immunoblot (B), and EpCAM cell surface protein levels by extracellular immunostaining and flow cytometry (C and D) in Du145, DuCaP, LNCaP, PC3, EP156T, and RWPE-1 cells.

Mentions: In our tissue analysis, we found EpCAM overexpression more pronounced at protein compared to mRNA level. Tissue mRNA data were mainly derived from array experiments performed on macro-dissected tissues containing proportions of non-epithelial cell types such as stromal, endothelial and immune cells. To discriminate whether the discrepancy between EpCAM mRNA and protein level is a true biologic difference or arises from tissue sample composition, we extended our analysis to in vitro cell culture models. We confirmed overexpression of EpCAM protein in PCa cell lines compared to non-cancerous prostate epithelial cells by immunoblot (total protein) and flow cytometry analyses (cell surface protein). Epithelial cell adhesion molecule cell surface levels were 16.7±8.8-fold (mean±s.d.) elevated in PCa compared to non-cancerous prostate cell lines. Epithelial cell adhesion molecule mRNA levels determined by qRT–PCR (2.5±2.8-fold overexpression in PCa), however, did not reflect the large differences observed on protein level (Figure 3A–D). In fact, the PCa cell lines LNCaP and PC3 express EpCAM mRNA levels comparable to non-cancerous cell lines EP156T and RWPE-1, whereas EpCAM protein levels in LNCaP and PC3 were clearly detectable by both immunoblot (total protein) and flow cytometry (cell surface protein), while at the detection limit in EP156T and RWPE-1 (Figure 3A–D). Thus, our data suggest that not only alterations in mRNA expression levels, but also changes in protein stabilities and protein turnover determine EpCAM expression levels in PCa.


EpCAM is overexpressed in local and metastatic prostate cancer, suppressed by chemotherapy and modulated by MET-associated miRNA-200c/205.

Massoner P, Thomm T, Mack B, Untergasser G, Martowicz A, Bobowski K, Klocker H, Gires O, Puhr M - Br. J. Cancer (2014)

EpCAM overexpression in PCa prevails at protein level. EpCAM mRNA expression levels were determined by qRT-PCR (A), EpCAM protein levels by immunoblot (B), and EpCAM cell surface protein levels by extracellular immunostaining and flow cytometry (C and D) in Du145, DuCaP, LNCaP, PC3, EP156T, and RWPE-1 cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150273&req=5

fig3: EpCAM overexpression in PCa prevails at protein level. EpCAM mRNA expression levels were determined by qRT-PCR (A), EpCAM protein levels by immunoblot (B), and EpCAM cell surface protein levels by extracellular immunostaining and flow cytometry (C and D) in Du145, DuCaP, LNCaP, PC3, EP156T, and RWPE-1 cells.
Mentions: In our tissue analysis, we found EpCAM overexpression more pronounced at protein compared to mRNA level. Tissue mRNA data were mainly derived from array experiments performed on macro-dissected tissues containing proportions of non-epithelial cell types such as stromal, endothelial and immune cells. To discriminate whether the discrepancy between EpCAM mRNA and protein level is a true biologic difference or arises from tissue sample composition, we extended our analysis to in vitro cell culture models. We confirmed overexpression of EpCAM protein in PCa cell lines compared to non-cancerous prostate epithelial cells by immunoblot (total protein) and flow cytometry analyses (cell surface protein). Epithelial cell adhesion molecule cell surface levels were 16.7±8.8-fold (mean±s.d.) elevated in PCa compared to non-cancerous prostate cell lines. Epithelial cell adhesion molecule mRNA levels determined by qRT–PCR (2.5±2.8-fold overexpression in PCa), however, did not reflect the large differences observed on protein level (Figure 3A–D). In fact, the PCa cell lines LNCaP and PC3 express EpCAM mRNA levels comparable to non-cancerous cell lines EP156T and RWPE-1, whereas EpCAM protein levels in LNCaP and PC3 were clearly detectable by both immunoblot (total protein) and flow cytometry (cell surface protein), while at the detection limit in EP156T and RWPE-1 (Figure 3A–D). Thus, our data suggest that not only alterations in mRNA expression levels, but also changes in protein stabilities and protein turnover determine EpCAM expression levels in PCa.

Bottom Line: Oppositely, re-induction of the epithelial phenotype through miRNAs miR-200c and miR-205, two inducers of mesenchymal-to-epithelial transition (MET), led to re-induction of EpCAM in chemoresistant cells.Furthermore, we prove that EpCAM cleavage, the first step of EpCAM signalling takes place in prostate cancer cells but in contrast to other cancer entities, EpCAM has no measurable impact on the proliferative behaviour of prostate cells, in vitro.In conclusion, our data confirm that EpCAM overexpression is an early event during prostate cancer progression.

View Article: PubMed Central - PubMed

Affiliation: 1] Experimental Urology, Department of Urology, Innsbruck Medical University, Innsbruck, Austria [2] Department of Otorhinolaryngology, Head and Neck Surgery, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT

Background: Expression of epithelial cell adhesion molecule (EpCAM) is deregulated in epithelial malignancies. Beside its role in cell adhesion, EpCAM acts as signalling molecule with tumour-promoting functions. Thus, EpCAM is part of the molecular network of oncogenic receptors and considered an interesting therapeutic target.

Methods: Here, we thoroughly characterised EpCAM expression on mRNA and protein level in comprehensive tissue studies including non-cancerous prostate specimens, primary tumours of different grades and stages, metastatic lesions, and therapy-treated tumour specimens, as well as in prostate cancer cell lines.

Results: Epithelial cell adhesion molecule was overexpressed at mRNA and at protein level in prostate cancer tissues and cell lines. Altered EpCAM expression was an early event in prostate carcinogenesis with an upregulation in low-grade cancers and further induction in high-grade tumours and metastatic lesions. Interestingly, EpCAM was repressed upon induction of epithelial-to-mesenchymal transition (EMT) following chemotherapeutic treatment with docetaxel. Oppositely, re-induction of the epithelial phenotype through miRNAs miR-200c and miR-205, two inducers of mesenchymal-to-epithelial transition (MET), led to re-induction of EpCAM in chemoresistant cells. Furthermore, we prove that EpCAM cleavage, the first step of EpCAM signalling takes place in prostate cancer cells but in contrast to other cancer entities, EpCAM has no measurable impact on the proliferative behaviour of prostate cells, in vitro.

Conclusions: In conclusion, our data confirm that EpCAM overexpression is an early event during prostate cancer progression. Epithelial cell adhesion molecule displays a dynamic, heterogeneous expression and associates with epithelial cells rather than mesenchymal, chemoresistant cells along with processes of EMT and MET.

Show MeSH
Related in: MedlinePlus