Expression Profile of E-cadherin and N-cadherin in Urothelial Carcinoma of the Upper Urinary Tract is Associated with Disease Recurrence in Patients Undergoing Nephroureterectomy

[18F]AlF-NOTA-ADH-1: A new PET molecular radiotracer for imaging of N-cadherin-positive tumors

BACKGROUND

The cell adhesion molecule (CAM) N-cadherin has become an important target for tumor therapy. The N-cadherin antagonist, ADH-1, exerts significant antitumor activity against N-cadherin-expressing cancers.

METHODS

In this study, [18F]AlF-NOTA-ADH-1 was radiosynthesized. An in vitro cell binding test was performed, and the biodistribution and micro-PET imaging of the probe targeting N-cadherin were also studied in vivo.

RESULTS

Radiolabeling of ADH-1 with [18F]AlF achieved a yield of up to 30% (not decay-corrected) with a radiochemical purity of >97%. The cell uptake study showed that Cy3-ADH-1 binds to SW480 cells but weakly binds to BXPC3 cells in the same concentration range. The biodistribution results demonstrated that [18F]AlF-NOTA-ADH-1 had a good tumor/muscle ratio (8.70±2.68) in patient-derived xenograft (PDX) tumor xenografts but a lower tumor/muscle ratio (1.91±0.69) in SW480 tumor xenografts and lowest tumor/muscle ratio (0.96±0.32) in BXPC3 tumor xenografts at 1 h post-injection (p.i.) These findings were in accordance with the immunohistochemistry results. The micro PET imaging results revealed good [18F]AlF-NOTA-ADH-1 tumor uptake in pancreatic cancer PDX xenografts with strong positive N-calcium expression, while lower tumor uptake in SW480 xenografts with positive expression of N-cadherin, and significantly lower tumor uptake in BXPC3 xenografts with low expression of N-cadherin, which was consistent with the biodistribution and immunohistochemistry results. The N-cadherin-specific binding of [18F]AlF-NOTA-ADH-1 was further verified by a blocking experiment involving coinjection of a non radiolabeled ADH-1 peptide, resulting in a significant reduction in tumor uptake in PDX xenografts and SW480 tumor.

CONCLUSION

[18F]AlF-NOTA-ADH-1 was successfully radiosynthesized, and Cy3-ADH-1 showed favorable N-cadherin-specific targeting ability by in vitro data. The biodistribution and microPET imaging of the probe further showed that [18F]AlF-NOTA-ADH-1 could discern different expressions of N-cadherin in tumors. Collectively, the findings demonstrated the potential of [18F]AlF-NOTA-ADH-1 as a PET imaging probe for non-invasive evaluation of the N-cadherin expression in tumors.

A multi-institutional retrospective study of open versus laparoscopic nephroureterectomy focused on the intravesical recurrence

AIM

Intravesical recurrence (IVR) after nephroureterectomy for upper tract urothelial carcinoma (UTUC) is relatively frequent, occurring in about 30-50% of patients. The aim of this study was to investigate the differences of the prognosis and IVR between open and laparoscopic surgery and to elucidate the risk factor of IVR.

PATIENTS AND METHODS

We retrospectively analyzed data from 403 patients with UTUC treated with laparoscopic or open nephroureterectomy at six affiliated hospitals between 1990 and 2015. The clinicopathological factors of each group were examined using Kaplan-Meier plots, and univariate and multivariate analyses.

RESULTS

There was no difference in recurrence and cancer-specific mortality between open and laparoscopic surgery in univariate and multivariate analyses. There was no significant difference in IVR rate between the laparoscopic and open groups (p = .22). Among the patients with IVR, 84% of patients relapsed within 2 years. Univariate analysis of IVR showed a significant increase in patients with low-grade (p = .03, HR = 1.64) or low-stage urothelial carcinoma (pT1 or lower, p = .006, HR = 1.77) with no lymph node involvement (p = .002, HR = 10.3) or lymphovascular invasion (p = .009, HR = 1.79). Surgical modality was not an independent factor. In multivariate analysis, there was no independent predictive factor for IVR.

CONCLUSIONS

There was no difference in recurrence, cancer-specific mortality, and IVR between open and laparoscopic surgery. On the other hand, our results suggested that the low malignant potential tumor may be a risk factor for IVR. This finding provides insight into IVR, which may help with the development of personalized prevention and treatment strategies.

High N-Cadherin Protein Expression in Ovarian Cancer Predicts Poor Survival and Triggers Cell Invasion

Ovarian cancer (OC) is among the most lethal cancer among all gynaecological malignancies. Since most OC patients are diagnosed only at advanced stages mainly because of their imperceptible/nonspecific symptoms, survival rates are low. Therefore, more molecular biomarkers are needed to achieve more effective molecular stratification for better prognostic and theranostic outcomes. The cadherin family, particularly N-cadherin (N-CAD; also known as CDH2), is critical for cell-cell adhesion and epithelial- mesenchymal transition (EMT) of cancer. N-CAD protein has also been shown to be overexpressed in many advanced carcinomas. The aim of this study was to investigate the expression patterns of N-CAD protein, determine their correlations with the clinicopathological features of OC patients, and evaluate its prognostic value and involvement in EMT and metastasis. Protein expression of N-CAD was studied in 117 formalin-fixed and paraffin-embedded (FFPE) blocks from patients diagnosed with OC using Tissue Microarray and immunohistochemistry techniques. The N-CAD protein was overexpressed in 58% of our OC cohort. Furthermore, its cytoplasmic overexpression was significantly correlated with tumor grade (p= 0.05), tumor subtype (p= 0.05), tumor necrosis (p= 0.01), and age at menarche (p= 0.002). Interestingly, Kaplan-Meier analysis showed a significant correlation of disease-free survival (DFS) with OC patients with cytoplasmic N-CAD overexpression (p< 0.03, log rank). Patients with high N-CAD expression have approximately twice the recurrence rate at 5-year follow-up. The results of this study demonstrate a poor prognostic role of N-CAD overexpression in OC, which is reflected in higher recurrence and death rates of OC and its molecular contribution to EMT and distant metastasis. Therefore, OC patients with overexpressed N-CAD need to be monitored more frequently and closely. Further studies with larger patient cohorts are needed to validate these findings, demystify the role of N-CAD in OC pathophysiology, and further investigate its role as a potential therapeutic target.

Endoscopic Ultrasound-guided Fine Needle Aspiration for the Diagnosis of Duodenal Stenosis Due to Urothelial Carcinoma

Upper tract urothelial carcinoma (UTUC) initially presents with hematuria and hydronephrosis. We report a case of UTUC presenting with initial findings of duodenal stenosis before the appearance of hydronephrosis. A 59-year-old man presented with upper abdominal symptoms on his initial visit. Esophagogastroduodenoscopy (EGD) revealed circumferential stenosis at the descending part of the duodenum. However, the underlying cause of duodenal stenosis was unknown as repeated histopathological examinations of endoscopic biopsy specimens showed no specific findings. We then performed endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) of the thickened duodenal wall, and successfully diagnosed duodenal metastasis of UTUC. EUS-FNA is an effective diagnostic method in cases in which the cause of duodenal stenosis is unknown.

Role of Cadherins in Cancer-A Review

Cadherins play an important role in tissue homeostasis, as they are responsible for cell-cell adhesion during embryogenesis, tissue morphogenesis, differentiation and carcinogenesis. Cadherins are inseparably connected with catenins, forming cadherin-catenin complexes, which are crucial for cell-to-cell adherence. Any dysfunction or destabilization of cadherin-catenin complex may result in tumor progression. Epithelial mesenchymal transition (EMT) is a mechanism in which epithelial cadherin (E-cadherin) expression is lost during tumor progression. However, during tumorigenesis, many processes take place, and downregulation of E-cadherin, nuclear β-catenin and p120 catenin (p120) signaling are among the most critical. Additional signaling pathways, such as Receptor tyrosine kinase (RTK), Rho GTPases, phosphoinositide 3-kinase (PI3K) and Hippo affect cadherin cell-cell adhesion and also contribute to tumor progression and metastasis. Many signaling pathways may be activated during tumorigenesis; thus, cadherin-targeting drugs seem to limit the progression of malignant tumor. This review discusses the role of cadherins in selected signaling mechanisms involved in tumor growth. The clinical importance of cadherin will be discussed in cases of human and animal cancers.

Does reduced E-cadherin expression correlate with poor prognosis in patients with upper tract urothelial cell carcinoma?: A systematic review and meta-analysis

BACKGROUND

E-cadherin has emerged as a prognostic factor of urothelial cell carcinoma. In the present work we investigate the relationship between expression of E-cadherin and clinical outcomes, following radical nephroureterectomy for upper tract urothelial cell carcinoma.

METHODS

We systematically searched PubMed, Embase, Cochrane Library, and Web of Science databases to identify eligible studies published until July 2017.

RESULT

Six studies were included in the meta-analysis, with a total of 1014 patients. The pooled hazard ratio (HR) for recurrence-free survivor was 0.69 (95% confidence interval [CI], 0.44-1.09, I = 63%, P = .04). Also, reduced E-cadherin was not significantly associated with poor cancer-specific survivor (pooled HR, 1.40; 95% CI, 0.66-1.43, I = 54%, P = .11). The pooled HR for overall survivor was not statistically significant (pooled HR, 0.68; 95% CI, 0.32-1.46, I = 80%, P = .007). The results of the Begg and Egger tests suggested that publication bias was not evident in this meta-analysis.

CONCLUSIONS

Reduced E-cadherin expression did not appear to be significantly associated with disease prognosis after nephroureterectomy in the meta-analysis. However, further high quality, prospective studies are warranted to better address this issue.

N-cadherin in cancer metastasis, its emerging role in haematological malignancies and potential as a therapeutic target in cancer

In many types of solid tumours, the aberrant expression of the cell adhesion molecule N-cadherin is a hallmark of epithelial-to-mesenchymal transition, resulting in the acquisition of an aggressive tumour phenotype. This transition endows tumour cells with the capacity to escape from the confines of the primary tumour and metastasise to secondary sites. In this review, we will discuss how N-cadherin actively promotes the metastatic behaviour of tumour cells, including its involvement in critical signalling pathways which mediate these events. In addition, we will explore the emerging role of N-cadherin in haematological malignancies, including bone marrow homing and microenvironmental protection to anti-cancer agents. Finally, we will discuss the evidence that N-cadherin may be a viable therapeutic target to inhibit cancer metastasis and increase tumour cell sensitivity to existing anti-cancer therapies.

Tissue-based molecular markers in upper tract urothelial carcinoma and their prognostic implications

Upper tract urothelial carcinoma (UTUC) is a rare and aggressive disease that is associated with high rates of recurrence and death. Radical nephroureterectomy (RNU) with excision of the bladder cuff is considered the standard of care for high-risk UTUC, whereas kidney-sparing techniques can be indicated for select patients with low-risk disease. There is a significant lack of clinical and pathological prognostic factors for stratifying patients with regard to making treatment decisions. Incorporation of tissue-based molecular markers into prognostic tools could help accurately stratify patients for clinical decision-making in this heterogeneous disease. Although the number of studies on tissue-based markers in UTUC has risen dramatically in the past several years-many of which are based on single centers and small cohorts, with a low level of evidence-many discrepancies remain between their results. Nevertheless, certain biomarkers are promising tools, necessitating prospective multi-institution studies to validate their function.

Distinct subcellular localization of E-cadherin between epithelioid angiomyolipoma and triphasic angiomyolipoma: A preliminary case-control study

Epithelioid angiomyolipoma (EAML) is a rare variant of angiomyolipoma (AML). Previous studies have demonstrated that epithelial (E-)cadherin is expressed in two subtypes of AML, EAML and triphasic AML; however, the expression pattern of E-cadherin remains unclear. In the present study, a preliminary case-control study was conducted to determine the expression pattern of E-cadherin between EAML and triphasic AML, the control, focusing on the subcellular localization and expression category of E-cadherin. No significant difference was identified in the age, sex, history of tuberous sclerosis, smoking and alcohol consumption between the two groups (P>0.05). In EAML, 9 patients were categorized as exhibiting a low risk of malignant behavior and the other two were categorized as exhibiting an intermediate or high risk of malignant behavior. The proportion of cases expressing E-cadherin, human melanoma black-45 (HMB45), melanoma antigen recognized by T cells 1 (Mart1/Melan A), smooth muscle actin and progesterone receptor were 95.5 (21/22), 95.5 (21/22), 86.4 (19/22), 77.3 (17/22) and 86.4% (19/22), respectively. E-cadherin was identified to be localized, using staining techniques, in the cell membrane and/or cytoplasm. The subcellular localization of E-cadherin was significantly different between EAML and triphasic AML; the majority of EAML cases revealed membranous and cytoplasmic staining, whereas triphasic AML cases demonstrated cytoplasmic staining (P=0.0093). The expression of E-cadherin may be positively associated with HMB45 (P=0.0044) and Mart1/Melan A (P=0.0049). The results of the present study identified that the subcellular localization of E-cadherin may be different between EAML and the control group of triphasic AML. Additionally, E-cadherin and melanocytic markers may be co-expressed in distinct subtypes of AML. A follow-up study with a large sample size to validate the results of the present study, followed by a mechanistic study based on cell lines to determine any significance, are warranted.

Prognostic significance of PD-L1 expression on tumor cells and tumor-infiltrating mononuclear cells in upper tract urothelial carcinoma

Immunotherapy targeting the programmed death-1 (PD-1) receptor/PD-1 ligand (PD-L1) pathway has shown promising results in several malignancies. However, the prognostic significance of PD-L1 expression remains unknown in patients with upper tract urothelial carcinoma (UTUC). This study aimed to evaluate PD-L1 expression and its association with clinicopathological characteristics and oncological outcomes in UTUC patients. PD-L1 expression on tumor cells and tumor-infiltrating mononuclear cells (TIMCs), and E-cadherin and N-cadherin expression on tumor cells were assessed by immunohistochemistry in a cohort of 162 patients with UTUC. Associations of PD-L1 expression on tumor cells and TIMCs with clinicopathological characteristics and cancer-specific survival (CSS) were evaluated. Out of 162 patients, 20 (12.3%) and 35 (21.6%) had positive PD-L1 expression on tumor cells and TIMCs, respectively. Decreased E-cadherin expression was associated with PD-L1 positivity on tumor cells (P = 0.048) and PD-L1 negativity on TIMCs (P = 0.033). PD-L1 expression on tumor cells was higher in patients with preoperative chronic kidney disease (CKD) stage 4-5 than in those with no CKD or CKD stage 1-3 (P = 0.011). PD-L1 was differentially expressed in tumor cells and TIMCs in UTUC. Multivariate analyses revealed that PD-L1 expression on tumor cells independently predicted shorter CSS (P = 0.012), whereas PD-L1 expression on TIMCs independently predicted longer CSS (P = 0.034).

Novel variants in MLL confer to bladder cancer recurrence identified by whole-exome sequencing

Bladder cancer (BC) is distinguished by high rate of recurrence after surgery, but the underlying mechanisms remain poorly understood. Here we performed the whole-exome sequencing of 37 BC individuals including 20 primary and 17 recurrent samples in which the primary and recurrent samples were not from the same patient. We uncovered that MLL, EP400, PRDM2, ANK3 and CHD5 exclusively altered in recurrent BCs. Specifically, the recurrent BCs and bladder cancer cells with MLL mutation displayed increased histone H3 tri-methyl K4 (H3K4me3) modification in tissue and cell levels and showed enhanced expression of GATA4 and ETS1 downstream. What's more, MLL mutated bladder cancer cells obtained with CRISPR/Cas9 showed increased ability of drug-resistance to epirubicin (a chemotherapy drug for bladder cancer) than wild type cells. Additionally, the BC patients with high expression of GATA4 and ETS1 significantly displayed shorter lifespan than patients with low expression. Our study provided an overview of the genetic basis of recrudescent bladder cancer and discovered that genetic alterations of MLL were involved in BC relapse. The increased modification of H3K4me3 and expression of GATA4 and ETS1 would be the promising targets for the diagnosis and therapy of relapsed bladder cancer.

Prognostic role of expression of N-cadherin in patients with upper tract urothelial carcinoma: a multi-institutional study

Purpose

To assess the role of N-cadherin as prognostic biomarker in patients with upper tract urothelial carcinoma (UTUC) in a large multi-institutional cohort of patients.

Patients and methods

Immunohistochemistry was used to evaluate the status of N-cadherin expression in 678 patients with unilateral sporadic UTUC treated with radical nephroureterectomy. N-cadherin was considered positive if any immunoreactivity with membranous staining was detected. The Kaplan–Meier method was used to estimate recurrence-free survival, overall survival and cancer-specific survival. Disease recurrence, overall mortality and cancer-specific mortality probabilities were tested in Cox regression models.

Results

Expression of N-cadherin was observed in 292 (43.1%) of patients, and it was associated with advanced tumour stage (p < 0.04), lymph node metastases (p = 0.04) and sessile architecture (p < 0.02). Within a median follow-up of 37.5 months (IQR 20–66), 171 patients (25.2%) experienced disease recurrence and 150 (22.1%) died from UTUC. In univariable analyses, N-cadherin expression was significantly associated with higher probability of recurrence (p = 0.01), but not overall (p = 0.9) or cancer-specific mortality (p = 0.06). When adjusted for the effects of all available confounders, N-cadherin was not associated with any of the survival outcomes.

Conclusion

N-cadherin is expressed in approximately 2/5 of UTUs. It is associated with adverse pathologic factors but not with survival outcomes. Its clinical value remains limited.

Electronic supplementary material

The online version of this article (doi:10.1007/s00345-016-1968-2) contains supplementary material, which is available to authorized users.

Loss of N-Cadherin Expression in Tumor Transplants Produced From As+3- and Cd+2-Transformed Human Urothelial (UROtsa) Cell Lines

BACKGROUND

Epithelial to mesenchymal transition is a process in which a cell experiences a loss of epithelial cell characteristics and acquires a more mesenchymal cell phenotype. In cancer, epithelial to mesenchymal transition has been proposed to play an important role during specific stages of tumor progression. The role epithelial to mesenchymal transition and mesenchymal to epithelial transition might play in toxicant-induced urothelial cancer is unknown.

METHODS

Real-time PCR, Western blotting, immuno-histochemistry and immuno-fluorescence were used to determine the expression of E- and N-cadherin in the UROtsa parent, the As+3- and Cd+2-transformed cell lines, the spheroids isolated from these cell lines as well as the tumor heterotransplants that were produced by the injection of the transformed cells into immune compromised mice.

RESULTS

This study showed that N-cadherin expression was increased in 6 As+3- and 7 Cd+2- transformed cell lines generated from human urothelial cells (UROtsa). The expression varied within each cell line, with 10% to 95% of the cells expressing N-cadherin. Tumors produced from these cell lines showed no expression of the N-cadherin protein. Spheroids which are made up of putative cancer initiating cells produced from these cell lines showed only background expression of N-cadherin mRNA, increased expression of aldehyde dehydrogenase 1 mRNA and produced tumors which did not express N-cadherin. There was no change in the expression of E-cadherin in the tumors, and the tumors formed by all the As+3 and Cd+2-transformed cell lines and cancer initiating cells stained intensely and uniformly for E-cadherin.

CONCLUSIONS

The finding that the cells expressing N-cadherin gave rise to tumors with no expression of N-cadherin is in agreement with the classical view of epithelial to mesenchymal transition. Epithelial to mesenchymal transition and N-cadherin are associated with dissemination and not with the ability to establish new tumor growth. Mesenchymal to epithelial transition and E-cadherin are viewed as necessary for a cell to establish a new metastatic site. The lack of N-cadherin expression in tumor transplants is consistent with E-cadherin expressing cells "seeding" a site for tumor growth. The study shows that a minority population of cultured cells can be the initiators of tumor growth.

Prognostic role of decreased E-cadherin expression in patients with upper tract urothelial carcinoma: a multi-institutional study

PURPOSE

To assess the role of E-cadherin as prognostic biomarker in upper tract urothelial carcinoma (UTUC) in a large multi-institutional cohort of patients.

METHODS

Immunohistochemistry technique was used to evaluate E-cadherin expression in 678 patients with unilateral, sporadic UTUC treated with RNU. E-cadherin expression was considered decreased if 10 % or more cells had decreased expression (<90 %).

RESULTS

Decreased E-cadherin expression was observed in 353 patients (52.1 %) and was associated with advanced pathological stage (P < 0.001), higher grade (P < 0.001), lymph node metastasis (P = 0.006), lymphovascular invasion (P < 0.001), concomitant carcinoma in situ (P < 0.001), multifocality (P = 0.004), tumor necrosis (P = 0.020) and sessile architecture (P < 0.001). Within a median follow-up of 30 months (interquartile range 15-57), 171 patients (25.4 %) experienced disease recurrence and 150 (21.9 %) died from UTUC. In univariable analyses, decreased E-cadherin expression was significantly associated with worse recurrence-free survival (P < 0.001) and cancer-specific survival CSS (P = 0.006); however, in multivariable analyses, it was not (P = 0.74 and 0.84, respectively). The lack of independent prognostic value of E-cadherin remained true in all subgroup analyses.

CONCLUSION

In UTUC patients treated with RNU, decreased E-cadherin expression is associated with features of biologically and clinically aggressive disease and worse outcome in univariable, but not multivariable, analyses. If E-cadherin's association with factors of advanced disease is confirmed on UTUC biopsy specimens, it could be used to help in the clinical decision-making regarding kidney-sparing approaches and/or neo-adjuvant chemotherapy.

Impact of smoking status on bladder tumor recurrence after radical nephroureterectomy for upper tract urothelial carcinoma

PURPOSE

Although smoking status has a significant association with clinical features in patients with bladder cancer, there are few reports of the impact of smoking on the clinical outcome of upper tract urothelial cancer. We investigated the possible influence of smoking status on bladder tumor recurrence after radical nephroureterectomy.

MATERIALS AND METHODS

We identified a study population of 245 consecutive patients treated surgically for upper tract urothelial cancer at our 3 institutions between 1994 and 2010. We analyzed associations between subsequent bladder tumor recurrence and patient clinicopathological parameters, including smoking status.

RESULTS

The 3-year bladder tumor recurrence-free survival rate was 32.6% in current smokers, 37.6% in former smokers and 61.7% in nonsmokers. Multivariate analysis revealed that male gender (HR 1.90, 95% CI 1.15-3.16, p = 0.013) and smoking status (former vs none HR 1.77, 95% CI 1.07-2.93, p = 0.027 and current vs none HR 1.58, 95% CI 1.03-2.42, p = 0.035) were independent risk factors for subsequent bladder tumor recurrence. Also, of patients with a positive smoking history those with 50 pack-years or greater showed a significantly higher incidence of bladder tumor recurrence after radical nephroureterectomy (HR 2.00, p = 0.003).

CONCLUSIONS

Positive smoking history and male gender were independent risk factors for bladder tumor recurrence after radical nephroureterectomy. A larger number of cigarettes smoked may increase the incidence of bladder tumor recurrence in patients with upper tract urothelial cancer.

Significance of ureteroscopic biopsy grade in patients with upper tract urothelial carcinoma

BACKGROUND

The objective of this study was to assess the significance of the ureteroscopic biopsy grade for patients with upper tract urothelial carcinoma (UTUC).

PATIENTS AND METHODS

This study included 40 patients who were diagnosed with a single focus of UTUC by ureteroscopic biopsy and subsequently underwent nephroureterectomy. The significance of the biopsy grade as a predictive factor for pathological outcomes of nephroureterectomy was retrospectively analyzed.

RESULTS

Of these 40 patients, 19 (47.5%) and 21 (52.5%) were diagnosed with low and high grade UTUC, respectively. The ureteroscopic biopsy grade matched the pathological grade of surgically resected specimens in 35 of the 40 cases (87.5%), and there was a significant correlation between the biopsy and pathological grades (p < 0.001). Furthermore, the biopsy grade was also shown to be closely associated with the pathological stage (p < 0.001); that is, only 1 of the 19 patients (5.3%) with biopsy low grade UTUC were pathologically diagnosed as having muscle invasive disease, while 17 of the 21 patients (81.0%) with biopsy high grade UTUC appeared to show tumor invasion into muscle or deeper.

CONCLUSIONS

The grade of UTUC on ureteroscopic biopsy could provide accurate diagnostic information on the final pathology of nephroureterectomy specimens.

Epithelial-to-mesenchymal transition leads to docetaxel resistance in prostate cancer and is mediated by reduced expression of miR-200c and miR-205

Docetaxel is a standard chemotherapy for patients with metastatic prostate cancer. However, the response is rather limited and not all of the patients benefit from this treatment. To uncover key mechanisms of docetaxel insensitivity in prostate cancer, we have established docetaxel-resistant sublines. In this study, we report that docetaxel-resistant cells underwent an epithelial-to-mesenchymal transition during the selection process, leading to diminished E-cadherin levels and up-regulation of mesenchymal markers. Screening for key regulators of an epithelial phenotype revealed a significantly reduced expression of microRNA (miR)-200c and miR-205 in docetaxel-resistant cells. Transfection of either microRNA (miRNA) resulted in re-expression of E-cadherin. Functional assays confirmed reduced adhesive and increased invasive and migratory abilities. Furthermore, we detected an increased subpopulation with stem cell-like properties in resistant cells. Tissue microarray analysis revealed a reduced E-cadherin expression in tumors after neoadjuvant chemotherapy. Low E-cadherin levels could be linked to tumor relapse. The present study uncovers epithelial-to-mesenchymal transition as a hallmark of docetaxel resistance. Therefore, we suggest that this mechanism is at least in part responsible for chemotherapy failure, with implications for the development of novel therapeutics.