The role of the desmosomal protein desmocollin 2 in tumour progression in triple negative breast cancer patients.

BACKGROUND: The disruption of epithelial features represents a critical step during breast cancer spread. In this context, the dysregulation of desmosomal proteins has been associated with malignant progression and metastasis formation. Curiously, both tumour suppressive and pro-metastatic roles have been attributed to desmosomal structures in different cancer entities. In the present study, we describe the pro-metastatic role of the desmosomal protein desmocollin 2 (DSC2) in breast cancer. METHODS: We analysed the prognostic role of DSC2 at mRNA and protein level using microarray data, western blot analysis and immunohistochemistry. Functional consequences of DSC2 overexpression and DSC2 knock down were investigated in the triple negative breast cancer (TNBC) cell line MDA-MB-231 and its brain-seeking subline MDA-MB-231-BR, respectively in vitro and in vivo. RESULTS: We found a significantly higher DSC2 expression in the more aggressive molecular subtypes HER2-positive and TNBC than in luminal breast cancers, as well as a significant correlation between increased DSC2 expression and a shorter disease-free-also in multivariate analysis-and overall survival. Additionally, a significant association between DSC2 expression in the primary tumour and an increased frequency of cerebral and lung metastasis could be observed. In vitro, ectopic DSC2 expression or DSC2 down-regulation in MDA-MB-231 and MDA-MB-231-BR led to a significant tumour cell aggregation increase and decrease, respectively. Furthermore, tumour cells displaying higher DSC2 levels showed increased chemoresistance in 3D structures, but not 2D monolayer structures, suggesting the importance of cell aggregation as a means for reduced drug diffusion. In an in vivo brain dissemination xenograft mouse model, reduced expression of DSC2 in the brain-seeking TNBC cells led to a decreased amount of circulating tumour cells/clusters and, in turn, to fewer and smaller brain metastatic lesions. CONCLUSION: We conclude that high DSC2 expression in primary TNBC is associated with a poorer prognosis, firstly by increasing tumour cell aggregation, secondly by reducing the diffusion and effectiveness of chemotherapeutic agents, and, lastly, by promoting the circulation and survival of tumour cell clusters, each of which facilitates distant organ colonisation.

TGFB-induced factor homeobox 1 (TGIF) expression in breast cancer.

BACKGROUND: Breast cancer (BC) is the most frequent female cancer and preferentially metastasizes to bone. The transcription factor TGFB-induced factor homeobox 1 (TGIF) is involved in bone metabolism. However, it is not yet known whether TGIF is associated with BC bone metastasis or patient outcome and thus of potential interest. METHODS: TGIF expression was analyzed by immunohistochemistry in 1197 formalin-fixed, paraffin-embedded tissue samples from BC patients treated in the GAIN (German Adjuvant Intergroup Node-Positive) study with two adjuvant dose-dense schedules of chemotherapy with or without bisphosphonate ibandronate. TGIF expression was categorized into negative/low and moderate/strong staining. Endpoints were disease-free survival (DFS), overall survival (OS) and time to primary bone metastasis as first site of relapse (TTPBM). RESULTS: We found associations of higher TGIF protein expression with smaller tumor size (p = 0.015), well differentiated phenotype (p < 0.001) and estrogen receptor (ER)-positive BC (p < 0.001). Patients with higher TGIF expression levels showed a significantly longer disease-free (DFS: HR 0.75 [95%CI 0.59-0.95], log-rank p = 0.019) and overall survival (OS: HR 0.69 [95%CI 0.50-0.94], log-rank p = 0.019), but no association with TTPBM (HR 0.77 [95%CI 0.51-1.16]; p = 0.213). Univariate analysis in molecular subgroups emphasized that elevated TGIF expression was prognostic for both DFS and OS in ER-positive BC patients (DFS: HR 0.68 [95%CI 0.51-0.91]; log-rank p = 0.009, interaction p = 0.130; OS: HR 0.60 [95%CI 0.41-0.88], log-rank p = 0.008, interaction p = 0.107) and in the HER2-negative subgroup (DFS:HR 0.67 [95%CI 0.50-0.88], log-rank p = 0.004, interaction p = 0.034; OS: HR 0.57 [95%CI 0.40-0.81], log-rank p = 0.002, interaction p = 0.015). CONCLUSIONS: Our results suggest that moderate to high TGIF expression is a common feature of breast cancer cells and that this is not associated with bone metastases as first site of relapse. However, a reduced expression is linked to tumor progression, especially in HER2-negative breast cancer. TRIAL REGISTRATION: This clinical trial has been registered with ClinicalTrials.gov ; registration number: NCT00196872 .

Clinical relevance of H-RAS, K-RAS, and N-RAS mRNA expression in primary breast cancer patients.

PURPOSE: The RAS family comprises three proto-oncogenes (H-RAS, K-RAS, and N-RAS) and is among the most widely studied of oncogenes. The present study aimed at investigating the clinical relevance of mRNA levels of the three isoforms in a large group of breast cancer patients with a long-term follow-up. METHODS: 198 previously untreated patients were enrolled in the study. mRNA levels of K-RAS, H-RAS, and N-RAS were measured using microarray (Affymetrix HG-U133A). RESULTS: Elevated H-RAS levels were found significantly more frequently in patients with larger (p = 0.021) and ER-positive tumors (p = 0.048), while elevated K-RAS levels were associated with nodal positivity (p = 0.001) and HER2-positivity (p = 0.010). Patients with high N-RAS mRNA levels were more likely to be diagnosed with triple-negativity (p < 0.001) and higher grading (p = 0.001). Patients with high K-RAS levels were more likely to show an elevated H-RAS (p = 0.003). After a median follow-up of 183 months, patients with high N-RAS expression had significantly reduced overall survival (OS) compared with patients with low N-RAS (mean: 146.9 vs. 211.0 months; median 169.3 vs. not reached; p = 0.009). In patients with non-metastatic disease at the time of tissue sampling, mean disease-free survival (DFS) was 150.1 months for patients with high N-RAS versus 227.7 months with low N-RAS; median DFS was not reached (p = 0.004). The expression of H-RAS and K-RAS was not associated with DFS/OS. In the multivariable analysis, distant metastasis, HER2 positivity, and elevated N-RAS mRNA levels independently predicted reduced OS, while nodal status, HER2 status, and N-RAS predicted reduced DFS. CONCLUSIONS: Elevated N-RAS mRNA levels predict impaired clinical outcome; hypothetically, further exploration of the RAS signaling pathway might enable identifying potential targeted treatment strategies. The association between high N-RAS levels and the most aggressive among breast cancer subtypes, the triple-negative phenotype, for which targeted approaches are still lacking, underlines the need to further investigate the RAS family.

Mechanisms of Tumor-Lymphatic Interactions in Invasive Breast and Prostate Carcinoma.

During the last few years, diverse studies have shown that tumors can actively interact with the lymphatic system and promote metastases development. In order to examine the molecular mechanisms involved in this interaction, we co-cultured tumor and lymphatic endothelial cells (LEC) and subsequently analyzed the molecular alterations of LECs. Therefore, LECs were co-cultivated with either a highly or weakly metastatic breast cancer cell line using contact (mixture) and non-contact (transwell) co-cultures. mRNA profiles from LECs were subsequently analyzed for genes specifically induced by highly metastatic tumor cells ("metastatic specific"). Among the up-regulated "metastatic specific" genes, we found candidates involved in cell cycle, cell adhesion and motility (BST2, E-selectin, and HMMR), cytokines (CCL7, CXCL6, CXCL1, and CSF2) and factors of the complement system (C1R, C3, and CFB). Among the down-regulated genes, we detected the hyaluronan receptor STAB2, angiogenic factor apelin receptor (APLNR), and the glycosylation enzyme MAN1A1. In an additional prostate cancer co-culture model, we could confirm a "metastatic specific" upregulation of E-selectin and CCL7 in LECs after interaction with the prostate cancer cell lines LNCAP (highly metastatic) and DU145 (weakly metastatic). These data allowed us to identify a set of genes regulated in LECs during in vitro communication with cancer cells, which might subsequently facilitate lymphatic metastasis.

Prognostic relevance of the Golgi mannosidase MAN1A1 in ovarian cancer: impact of N-glycosylation on tumour cell aggregation.

BACKGROUND: Maturation of complex N-glycans involves the action of Golgi mannosidases and plays a major role in cancer progression. We recently showed a favourable prognostic role of α-mannosidase MAN1A1 in breast cancer mainly caused by alteration of certain adhesion molecules. METHODS: We analysed the protein expression of MAN1A1 in ovarian cancer (n = 204) using western blot and studied the impact of MAN1A1 itself and of MAN1A1-related glycosylation on the prognostic relevance of two adhesion molecules. Functional consequences of mannosidase inhibition using kifunensine and MAN1A1 knock out were investigated in ovarian cancer cells in vitro. RESULTS: Patients with high MAN1A1 expression in tumours showed significantly shorter RFS than those with low-MAN1A1 levels. Moreover, high MAN1A1 expression correlated significantly with advanced stage, lymph node involvement and distant metastasis. Further, the glycosylated adhesion molecule ALCAM reveals a significant adverse prognostic effect only in the presence of high MAN1A1 expression. In spheroid-formation assays, mannosidase inhibition and especially MAN1A1 knock out led to strong reduction of tumour cell aggregation. CONCLUSIONS: Our study demonstrates the unfavourable prognostic role of MAN1A1 in ovarian cancer, probably caused by an altered ability of spheroid formation, and the strong influence of this glycosylation enzyme on the prognostic impact of ALCAM.

Role of protein glycosylation in cancer metastasis.

Although altered glycosylation has been detected in human cancer cells decades ago, only investigations in the last years have enormously increased our knowledge about the details of protein glycosylation and its role in tumour progression. Many proteins, which are heavily glycosylated, i.e. adhesion proteins or proteases, play an important role in cancer metastasis that represents the crucial and frequently life-threatening step in progression of most tumour types. Compared to normal tissue, tumour cells often show altered glycosylation patters with appearance of new tumour-specific antigens. In this review, we give an overview about the role of glycosylation in tumour metastasis, describing recent results about O-glycans, N-glycans and glycosaminoglycans. We show that glycan structures, glycosylated proteins and glycosylation enzymes have influence on different steps of the metastatic process, including epithelial-mesenchymal transition (EMT), migration, invasion/intravasation and extravasation of tumour cells. Regarding the important role of cancer metastasis for patients survival, further knowledge about the consequences of altered glycosylation patterns in tumour cells is needed which might eventually lead to the development of novel therapeutic approaches.

Prognostic role of the sialyltransferase ST6GAL1 in ovarian cancer.

Aberrant sialylation of glycoproteins has been detected in many tumors, and upregulation of the beta-galactosamide alpha-2,6-sialyltransferase 1 (ST6GAL1) has been implicated with tumor aggressiveness and chemoresistance in experimental models. In our present study, we aimed to study the prognostic or predictive role of ST6GAL1 in ovarian carcinoma, using two independent ovarian cancer cohorts. ST6GAL1 mRNA levels were retrieved from a publicly available database (n = 517), and ST6GAL1 protein levels were analyzed by western blot analysis in a cohort of 204 ovarian tumor samples. The results were correlated with clinical and histological tumor parameters and follow-up information. High ST6GAL1 mRNA levels significantly correlated with lymphovascular invasion and shorter survival, whereas high ST6GAL1 protein expression was associated with advanced stage, distant metastasis and shorter recurrence-free intervals. In both cohorts the prognostic role was most pronounced in tumors without macroscopically visible residual tumor after surgery. In these cases, ST6GAL1 expression levels might help to identify cases with a higher risk of chemoresistance and metastatic relapse that might require an adapted therapeutic regime.

Reduced mannosidase MAN1A1 expression leads to aberrant N-glycosylation and impaired survival in breast cancer.

BACKGROUND: Alterations in protein glycosylation have been related to malignant transformation and tumour progression. We recently showed that low mRNA levels of Golgi alpha-mannosidase MAN1A1 correlate with poor prognosis in breast cancer patients. METHODS: We analysed the role of MAN1A1 on a protein level using western blot analysis (n=105) and studied the impact of MAN1A1-related glycosylation on the prognostic relevance of adhesion molecules involved in breast cancer using microarray data (n=194). Functional consequences of mannosidase inhibition using the inhibitor kifunensine or MAN1A1 silencing were investigated in breast cancer cells in vitro. RESULTS: Patients with low/moderate MAN1A1 expression in tumours showed significantly shorter disease-free intervals than those with high MAN1A1 levels (P=0.005). Moreover, low MAN1A1 expression correlated significantly with nodal status, grading and brain metastasis. At an mRNA level, membrane proteins ALCAM and CD24 were only significantly prognostic in tumours with high MAN1A1 expression. In vitro, reduced MAN1A1 expression or mannosidase inhibition led to a significantly increased adhesion of breast cancer cells to endothelial cells. CONCLUSIONS: Our study demonstrates the prognostic role of MAN1A1 in breast cancer by affecting the adhesive properties of tumour cells and the strong influence of this glycosylation enzyme on the prognostic impact of some adhesion proteins.

Elevated serum RAS p21 is an independent prognostic factor in metastatic breast cancer.

BACKGROUND: An important component of the RAS signalling pathway, the RAS p21 oncogene, is frequently hyperactivated in breast cancer. Its expression in tumor tissue has been linked to poor clinical outcome. This study was designed to evaluate the clinical relevance of RAS p21 levels in peripheral blood in a large cohort of metastatic breast cancer patients. METHODS: Two hundred fifty-one patients with metastatic breast cancer were enrolled in this prospective, multicentre, open-label, non-randomized study. Blood samples were collected before start of first-line or later-line treatment. RAS p21 was determined using a sandwich-type ELISA immunoassay. For the determination of the cutoff, blood samples from age-matched healthy controls were analyzed. A value above 452 pg/ml was regarded as elevated (mean + 2 x SD). In the univariate survival analysis, two other cutoffs were considered as well (50th and 75th percentile of patients, i.e. 229 pg/ml and 320 pg/ml). Circulating tumor cells (CTCs) were detected using the CellSearch system. RESULTS: 29 of 251 (12%) patients had RAS p21 levels above the cut-off level of 452 pg/ml. Clinical-pathological parameters, such as hormone receptor and HER2 status, line of therapy and CTC status, did not correlate with RAS p21 levels. Elevated RAS p21 was significantly associated with shorter progression-free and overall survival in the univariate analysis (median PFS: 3.9 months [95%-CI: 1.8-6.0] for patients with elevated RAS p21 levels versus 8.5 months [95%-CI: 7.4-9.5] with non-elevated levels [p = 0.01]; median OS: 7.1 months [95%-CI: 0.3-14.2] versus not reached [p = 0.002], respectively). When RAS p21 cutoffs other than 452 pg/ml were considered, elevated RAS p21 was significantly associated with OS but not with PFS. Classical clinical-pathological factors were included into a multivariate Cox regression analysis. In addition, factors previously shown to influence survival in a univariate analysis, such as serum HER2, CAIX and TIMP1, were included as well. In the multivariate analysis, RAS p21, presence of ≥5 CTCs per 7.5 ml blood, higher grading and higher line of therapy remained independent predictors of shorter OS. CONCLUSIONS: Metastatic breast cancer patients with elevated levels of circulating RAS p21 have significantly worse clinical outcome. Hypothetically, these patients might benefit from therapeutic strategies targeting RAS pathway. TRIAL REGISTRATION: Current Controlled Trials ISRCTN59722891 (DETECT); trial registration date: April, 17th 2010; the trial was registered retrospectively.

Role of HYAL1 expression in primary breast cancer in the formation of brain metastases.

BACKGROUND: The incidence of brain metastases in breast cancer patients has increased in the last years. However, the knowledge about tumor cell invasion in the brain is still very limited. Based on our recent study on cDNA microarray data of breast cancer patients, we hypothesized that two enzymes involved in the hyaluronan metabolism, namely, hyaluronan synthase 2 (HAS2) and hyaluronidase 1 (HYAL1) are associated with brain metastases formation. METHODS: Protein expression levels of hyaluronan, HAS2, and HYAL1 were analyzed in primary breast cancer, and metastatic tissue samples from different localizations (brain, bone, skin, liver, and lung) were included in four different cohorts by immunohistochemistry. Correlations of expression levels with clinical and pathological parameters were performed within the individual cohorts. RESULTS: Higher HYAL1 expression was detected among primary tumors from patients with subsequent brain metastases compared with those without brain metastases (p = 0.011). Interestingly, brain metastatic tissue showed a significantly reduced HYAL1 expression compared with the corresponding primary tumor (p = 0.003). HYAL1 expression in brain metastases was also significantly lower than in skin, liver, and lung metastases. Further, hyaluronan staining in brain metastases was mainly located on the surface of the tumor cells, whereas in all other metastatic sites hyaluronan was only detected in the extracellular matrix. We could not show an association of HAS2 with the formation of brain metastases. CONCLUSIONS: In conclusion, our results suggest that the enzyme HYAL1 plays a role in tumor dissemination and brain-specific colonization, rather than in subsequent metastatic out-growth.

E-Cadherin fragments as potential mediators for peritoneal metastasis in advanced epithelial ovarian cancer.

BACKGROUND: Peritoneal dissemination and retroperitoneal lymph node involvement are main routes for tumour spread of epithelial ovarian cancer (EOC), possibly determined by the intercellular connecting protein E-Cadherin (E-Cad) and its fragments. METHODS: Tumour tissue of 105 advanced EOC patients was evaluated for protein expression of E-Cad, ß-Catenin and Calpain by western blotting and immunohistochemistry. Expression patterns were compared between tumours with solely intraperitoneal (pT3c, pN0; n=41) and tumours with retroperitoneal metastases (pT1a-3c, pN1; n=64). Lysates of the EOC cell line SKOV3 and tumour tissue from the intraperitoneal group were tested for E-Cad expression following Calpain treatment. RESULTS: E-Cad full-length (E-Cad-FL, 120 kDa) and two major fragments at 85 kDa (E-Cad-85) and 23 kDa (E-Cad-23) were detected by western blotting. E-Cad-85 expression was significantly higher in tumours with solely intraperitoneal metastases and correlated strongly with E-Cad-23 and the protease Calpain. Calpain-mediated cleavage was identified as a potential mechanism to generate E-Cad-85 from E-Cad-FL by treating lysates from SKOV3 cells and tumour tissue with this enzyme. Increased cytoplasmic localisation of ß-Catenin in tumours with high E-Cad-85 expression corroborates that E-Cad-85 loses the binding site for ß-Catenin after fragmentation, enabling tumour cluster formation and peritoneal dissemination. CONCLUSIONS: Calpain-mediated E-Cad fragmentation appears to promote intraperitoneal EOC progression. Understanding these mechanisms might eventually lead to new tailored subtype-specific diagnostic and therapeutic interventions.

Circulating Cell-Free miR-373, miR-200a, miR-200b and miR-200c in Patients with Epithelial Ovarian Cancer.

In the present study, we investigated whether circulating cell-free microRNAs serve as potential biomarkers in epithelial ovarian cancer (EOC) patients. Circulating miR-373, miR-200a, miR-200b and miR-200c were quantified in a cohort of 60 EOC patients, 20 patients with benign ovarian diseases and 32 healthy women using quantitative TaqMan MicroRNA assays. The serum concentrations of cell-free miR-373, miR-200a, miR-200b and miR-200c were significantly higher in EOC patients than in healthy women (p = 0.0001). With a sensitivity of 83 % and a specificity of 100 %, the combination of miR-200a, miR-200b and miR-200c could differ between malignant and benign ovarian tumors (p = 0.0001). Elevated levels of these cell-free microRNAs could be detected in FIGO I-II and FIGO III-IV stages, grading G1-2 and G3 and lymph node-negative and -positive EOC. In conclusion, the increased serum levels of this microRNA panel have diagnostic value for distinguishing healthy controls and benign tumors from EOC.

Diagnostic and prognostic potential of serum miR-7, miR-16, miR-25, miR-93, miR-182, miR-376a and miR-429 in ovarian cancer patients.

BACKGROUND: Owing to late diagnosis in advanced disease stages, prognosis of patients with epithelial ovarian cancer (EOC) is poor. The quantification of deregulated levels of microRNAs could facilitate earlier diagnosis and improve prognosis of EOC. METHODS: Seven microRNAs (miR-7, miR-16, miR-25, miR-93, miR-182, miR-376a and miR-429) were quantified in the serum of 180 EOC patients and 66 healthy women by TaqMan PCR microRNA assays. Median follow-up time was 21 months. The effects of miR-7 and miR-429 on apoptosis, cell proliferation, migration and invasion were investigated in two (EOC) cell lines. RESULTS: Serum levels of miR-25 (P=0.0001) and miR-93 (P=0.0001) were downregulated, whereas those of miR-7 (P=0.001) and miR-429 (P=0.0001) were upregulated in EOC patients compared with healthy women. The four microRNAs discriminated EOC patients from healthy women with a sensitivity of 93% and a specificity of 92%. The levels of miR-429 positively correlated with CA125 values (P=0.0001) and differed between FIGO I-II and III-IV stages (P=0.001). MiR-429 was an independent predictor of overall survival (P=0.011). Overexpressed miR-429 in SKOV3 cells led to suppression of cell migration (P=0.037) and invasion (P=0.011). Increased levels of miR-7 were associated with lymph node metastases (P=0.0001) and FIGO stages III-IV (P=0.0001). Overexpressed miR-7 in SKOV3 cells resulted in increased cell migration (P=0.001) and invasion (P=0.011). Additionally, the increased levels of miR-376a correlated with FIGO stages III-IV (P=0.02). CONCLUSIONS: Our data indicate the diagnostic potential of miR-7, miR-25, miR-93 and miR-429 in EOC and the prognostic potential of miR-429. This microRNA panel may be promising molecules to be targeted in the treatment of EOC.

Relevance of ßGal-ßGalNAc-containing glycans and the enzymes involved in their synthesis for invasion and survival in breast cancer patients.

To study the influence of glycosylation on breast cancer progression by analyses on glycan, mRNA, and protein level. For detection of glycan structures, we performed lectin histochemistry with five lectins of different specificity (UEA-1, HPA, GNA, PNA, and PHA-L) on a tissue microarray with >400 breast cancer samples. For comparison, mRNA expression of glycosylation enzymes involved in the synthesis of HPA and PNA binding glycostructures (GALNT family members and C1GALT1) was analyzed in microarray data of 194 carcinomas. Additionally, C1GALT1 protein expression was analyzed by Western blot analysis in 106 tumors. Correlations with clinical and histological parameters including recurrence-free (RFS) and overall survival (OAS) were calculated. Positive binding of four lectins (HPA, GNA, PNA, and PHA-L) correlated significantly with parameters involved in tumor metastasis, namely lymphangiosis, vascular invasion, lymph node involvement, and presence of disseminated tumor cells in bone marrow. HPA and PNA binding also showed a negative prognostic impact in our cohort. Correspondingly, high expression of C1GALT1, GALNT1, GALNT8, or GALNT14 mRNA and C1GALT1 protein correlated significantly with shorter OAS. Notably, combined overexpression of C1GALT1/GALNT1 or C1GALT1/GALNT8 mRNA was associated with a significantly reduced OAS (HR 3.15 and 2.73) and RFS (HR 2.01 and 1.94), pointing to an additive influence of these enzymes. This prognostic impact retained significance in multivariate analysis including classical prognostic markers. Our data indicate that glycan structures containing ßGal-ßGalNAc residues and the enzymes involved in their synthesis play a role in breast cancer progression, at least partly by their promoting influence on haematogenic and lymphatic spread.

Prognostic relevance of glycosylation-associated genes in breast cancer.

Glycosylation of cellular proteins has important impact on their stability and functional properties, and glycan structures strongly influence cell adhesion. Many enzymes are involved in glycoconjugate synthesis and degradation, but there is only limited information about their role in breast cancer progression. Therefore, we retrieved RNA expression data of 202 glycosylation genes generated by microarray analysis (Affymetrix HG-U133A) in a cohort of 194 mammary carcinomas with long-term follow-up information. After univariate and multivariate Cox regression analysis, genes with independent prognostic value were identified. These were further analysed by Kaplan-Meier analysis and log-rank tests, and their prognostic value was validated in a second cohort of 200 tumour samples from patients without systemic therapy. In our first cohort, we identified 24 genes with independent prognostic value, coding for sixteen anabolic and eight catabolic enzymes. Functionally, these genes are involved in all important glycosylation pathways, namely O-glycosylation, N-glycosylation, O-fucosylation, synthesis of glycosaminoglycans and glycolipids. Eighteen genes also showed prognostic significance in chemotherapy-treated patients. In the second cohort, six of the 24 relevant genes were of prognostic significance (FUT1, FUCA1, POFUT1, MAN1A1, RPN1 and DPM1), whereas a trend was observed for three additional probesets (GCNT4, ST3GAL6 and UGCG). In a stratified analysis of molecular subtypes combining both cohorts, great differences appeared suggesting a predominant role of N-glycosylation in luminal cancers and O-glycosylation in triple-negative ones. Correlations of gene expression with metastases of various localizations point to a role of glycan structures in organ-specific metastatic spread. Our results indicate that various glycosylation reactions influence progression and metastasis of breast cancer and might thus represent potential therapeutic targets.

L1CAM is expressed in triple-negative breast cancers and is inversely correlated with androgen receptor.

BACKGROUND: Breast cancer is a heterogeneous disease displaying distinct molecular features and clinical outcome. The molecular profile of triple-negative breast cancers (TNBCs) overlaps with that of basal-like breast cancers that in turn show similarities with high-grade serous ovarian and endometrial carcinoma. L1CAM is an established biomarker for the latter cancers and we showed before that approximately 18% of primary breast cancers are positive for L1CAM and have a bad prognosis. Here we analysed the expression of L1CAM breast cancer subtypes. METHODS: We analyzed mRNA and protein expression data from different breast cancer cohorts for L1CAM, estrogen receptor, progesterone receptor, Her-2 and Androgen receptor (AR) and correlated the data. We performed Western blot analysis on tumor cell lysates and carried out chromatin-immuno-precipitation (CHIP) after AR overexpression. RESULTS: We find that L1CAM is expressed preferentially though not exclusively in TNBCs. Using the human cancer genome atlas database and two independent breast cancer cohorts we find that L1CAM is inversely correlated with androgen receptor (AR) expression. We found that L1CAM(high)AR(low) primary breast tumors have the worst clinical outcome. Overexpression of AR in MDA-MB436 breast cancer cells decreased L1CAM expression at the protein and mRNA level and CHIP-analysis revealed binding of AR to the L1CAM promoter region. CONCLUSIONS: These results suggest that L1CAM in breast cancer is under AR control. The data also strongly advocate the use of L1CAM assessment in breast cancer diagnosis. We suggest that L1CAM expression could be causally related to the bad prognosis of TNBCs.

Validity of the proliferation markers Ki67, TOP2A, and RacGAP1 in molecular subgroups of breast cancer.

High proliferation rates are characteristic of cancer, and proliferation markers make up the majority of genes included in RNA-based prognostic gene signatures applied for breast cancer patients. Based on prior data on differences in molecular subgroups of breast cancer, we hypothesized that the significance of single proliferation markers might differ in luminal, Her2-positive and triple-negative subtypes. Therefore, we compared mRNA expression data of Ki67, TOP2A, and RacGAP1 using a pool of 562 Affymetrix U133A microarrays from breast cancer samples. "Luminal," "triple-negative," and "Her2-positive" subcohorts were defined by ESR1 and ERBB2 mRNA expression using pre-defined cut-offs. The analysis of the three potential proliferation markers revealed subtype-specific differences: in luminal carcinomas, expression of all three markers was a significant indictor of early recurrence in univariate and multivariate analysis, but RacGAP1 was superior to Ki67 and TOP2A in significance. In triple-negative tumors, only Ki67 was a significant and independent marker, whereas none of the markers showed a significant prognostic impact in Her2-positive cases. Within the group of luminal carcinomas, the proliferation markers had different impact depending on the treatment of patients: in untreated patients, Ki67, TOP2A, and RacGAP1 were significant and independent prognostic markers. In chemotherapy-treated patients, overexpression of all three markers was predictive for early recurrence, but only RacGAP1 retained significance in multivariate analysis. In contrast, RacGAP1 was the only predictive proliferation marker in the endocrine treatment group. These data point to subtype-specific differences in the relevance of proliferation-associated genes, and RacGAP1 might be a strong prognostic and predictive marker in the luminal subgroup.

Platelet-derived growth factor receptor beta serum concentrations during first-line therapy in ovarian cancer.

OBJECTIVES: Angiogenesis plays an important role in ovarian cancer. The interaction of platelet-derived growth factor receptor-beta (PDGFR-ß) with vascular endothelial growth factor (VEGF) in the process of angiogenesis may represent an essential feature in the progression of the disease. METHODS: Patients with epithelial ovarian cancer, who underwent primary surgery and platinum-based first-line chemotherapy, were included. A total of 133 serum samples from 39 patients were analyzed. Samples were prospectively collected at 4 time points: (1) before surgery, (2) after surgery and before chemotherapy, (3) during chemotherapy and (4) after chemotherapy. Serum PDGFR-ß was quantified by ELISA. We analyzed the correlation of serum levels to chemotherapy response, progression-free and overall survival (PFS and OS) and the serum markers CA-125 and VEGF-165. RESULTS: Serum concentration of PDGFR-ß ranged between 4 and 72 ng/ml and increased significantly during first-line chemotherapy (p = 0.019). PDGFR-ß serum concentrations showed an inverse correlation with CA-125 and VEGF-165 after chemotherapy (r = -0.495, p = 0.003 and r = -0.345, p = 0.04, respectively). Increased PDGFR-ß serum levels after chemotherapy were significantly correlated with better PFS (p = 0.026) and OS (p = 0.013) in a univariate analysis. CONCLUSION: PDGFR-ß might be a useful biomarker in terms of prognosis and could be important as antiangiogenic agents become a component of standard treatment in ovarian cancer.

Tumor cell integrin ß4 and tumor stroma E-/P-selectin cooperatively regulate tumor growth in vivo.

BACKGROUND: The immunological composition of the tumor microenvironment has a decisive influence on the biological course of cancer and is therefore of profound clinical relevance. In this study, we analyzed the cooperative effects of integrin ß4 (ITGB4) on tumor cells and E-/P-selectin on endothelial cells within the tumor stroma for regulating tumor growth by shaping the local and systemic immune environment. METHODS: We used several preclinical mouse models for different solid human cancer types (xenograft and syngeneic) to explore the role of ITGB4 (shRNA-mediated knockdown in tumor cells) and E-/P-selectins (knockout in mice) for tumor growth; effects on apoptosis, proliferation and intratumoral signaling pathways were determined by histological and biochemical methods and 3D in vitro experiments; changes in the intratumoral and systemic immune cell composition were determined by flow cytometry and immunohistochemistry; chemokine levels and their attracting potential were measured by ELISA and 3D invasion assays. RESULTS: We observed a very robust synergism between ITGB4 and E-/P-selectin for the regulation of tumor growth, accompanied by an increased recruitment of CD11b+ Gr-1Hi cells with low granularity (i.e., myeloid-derived suppressor cells, MDSCs) specifically into ITGB4-depleted tumors. ITGB4-depleted tumors undergo apoptosis and actively attract MDSCs, well-known to promote tumor growth in several cancers, via increased secretion of different chemokines. MDSC trafficking into tumors crucially depends on E-/P-selectin expression. Analyses of clinical samples confirmed an inverse relationship between ITGB4 expression in tumors and number of tumor-infiltrating leukocytes. CONCLUSIONS: These findings suggest a distinct vulnerability of ITGB4Lo tumors for MDSC-directed immunotherapies.