Global transcriptional analysis identifies a novel role for SOX4 in tumor-induced angiogenesis.

The expression of the transcription factor SOX4 is increased in many human cancers, however, the pro-oncogenic capacity of SOX4 can vary greatly depending on the type of tumor. Both the contextual nature and the mechanisms underlying the pro-oncogenic SOX4 response remain unexplored. Here, we demonstrate that in mammary tumorigenesis, the SOX4 transcriptional network is dictated by the epigenome and is enriched for pro-angiogenic processes. We show that SOX4 directly regulates endothelin-1 (ET-1) expression and can thereby promote tumor-induced angiogenesis both in vitro and in vivo. Furthermore, in breast tumors, SOX4 expression correlates with blood vessel density and size, and predicts poor-prognosis in patients with breast cancer. Our data provide novel mechanistic insights into context-dependent SOX4 target gene selection, and uncover a novel pro-oncogenic role for this transcription factor in promoting tumor-induced angiogenesis. These findings establish a key role for SOX4 in promoting metastasis through exploiting diverse pro-tumorigenic pathways.

Prognostic relevance of tumor-infiltrating lymphocytes and immune checkpoints in pediatric medulloblastoma.

Pediatric medulloblastomas are the most frequently diagnosed embryonal tumors of the central nervous system. Current therapies cause severe neurological and cognitive side effects including secondary malignancies. Cellular immunotherapy might be key to improve survival and to avoid morbidity. Efficient killing of tumor cells using immunotherapy requires to overcome cancer-associated strategies to evade cytotoxic immune responses. Here, we examined the immune response and immune evasion strategies in pediatric medulloblastomas. Cytotoxic T-cells, infiltrating medulloblastomas with variable activation status, showed no correlation with overall survival of the patients. We found limited numbers of PD1+ T-cells and complete absence of PD-L1 on medulloblastomas. Medulloblastomas downregulated immune recognition molecules MHC-I and CD1 d. Intriguingly, expression of granzyme inhibitors SERPINB1 and SERPINB4 was acquired in 23% and 50% of the tumors, respectively. Concluding, pediatric medulloblastomas exploit multiple immune evasion strategies to overcome immune surveillance. Absence of PD-L1 expression in medulloblastoma suggest limited or no added value for immunotherapy with PD1/PD-L1 blockers.

Oncogenic role of cytomegalovirus in medulloblastoma?

Medulloblastoma is the most common solid tumor among children. Current therapeutic strategies for this malignancy include surgical resection, radiation therapy and chemotherapy. However, these treatments are accompanied with serious side effects such as neurological complications and psychosocial problems, due to the severity of treatment on the developing nervous system. To solve this problem, novel therapeutic approaches are currently being investigated. One of them is targeting human cytomegalovirus in medulloblastoma cancer cells. However, this approach is still under debate, since the presence of cytomegalovirus in medulloblastomas remains controversial. In this review, we discuss the current controversies on the role of cytomegalovirus in medulloblastoma oncogenesis and the potential of cytomegalovirus as a novel (immuno)therapeutic target.

Pediatric Primitive Neuroectodermal Tumors of the Central Nervous System Differentially Express Granzyme Inhibitors.

BACKGROUND: Central nervous system (CNS) primitive neuroectodermal tumors (PNETs) are malignant primary brain tumors that occur in young infants. Using current standard therapy, up to 80% of the children still dies from recurrent disease. Cellular immunotherapy might be key to improve overall survival. To achieve efficient killing of tumor cells, however, immunotherapy has to overcome cancer-associated strategies to evade the cytotoxic immune response. Whether CNS-PNETs can evade the immune response remains unknown. METHODS: We examined by immunohistochemistry the immune response and immune evasion strategies in pediatric CNS-PNETs. RESULTS: Here, we show that CD4+, CD8+, γδ-T-cells, and Tregs can infiltrate pediatric CNS-PNETs, although the activation status of cytotoxic cells is variable. Pediatric CNS-PNETs evade immune recognition by downregulating cell surface MHC-I and CD1d expression. Intriguingly, expression of SERPINB9, SERPINB1, and SERPINB4 is acquired during tumorigenesis in 29%, 29%, and 57% of the tumors, respectively. CONCLUSION: We show for the first time that brain tumors express direct granzyme inhibitors (serpins) as a potential mechanism to overcome cellular cytotoxicity, which may have consequences for cellular immunotherapy.

Oropharyngeal squamous cell carcinomas differentially express granzyme inhibitors.

OBJECTIVES: Patients with human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinomas (OPSCCs) have an improved prognosis compared to HPV-negative OPSCCs. Several theories have been proposed to explain this relatively good prognosis. One hypothesis is a difference in immune response. In this study, we compared tumor-infiltrating CD3+, CD4+, CD8+ T-cells, and granzyme inhibitors (SERPINB1, SERPINB4, and SERPINB9) between HPV-positive and HPV-negative tumors and the relation with survival. METHODS: Protein expression of tumor-infiltrating lymphocytes (TILs) (CD3, CD4, and CD8) and granzyme inhibitors was analyzed in 262 OPSCCs by immunohistochemistry (IHC). Most patients (67%) received primary radiotherapy with or without chemotherapy. Cox regression analysis was carried out to compare overall survival (OS) of patients with low and high TIL infiltration and expression of granzyme inhibitors. RESULTS: HPV-positive OPSCCs were significantly more heavily infiltrated by TILs (p < 0.001) compared to HPV-negative OPSCCs. A high level of CD3+ TILs was correlated with a favorable outcome in the total cohort and in HPV-positive OPSCCs, while it reached no significance in HPV-negative OPSCCs. There was expression of all three granzyme inhibitors in OPSCCs. No differences in expression were found between HPV-positive and HPV-negative OPSCCs. Within the group of HPV-positive tumors, a high expression of SERPINB1 was associated with a significantly worse overall survival. CONCLUSION: HPV-positive OPSCCs with a low count of CD3+ TILs or high expression of SERPINB1 have a worse OS, comparable with HPV-negative OPSCCs. This suggests that the immune system plays an important role in the carcinogenesis of the virally induced oropharynx tumors.

Hypoxia-Targeting Fluorescent Nanobodies for Optical Molecular Imaging of Pre-Invasive Breast Cancer.

PURPOSE: The aim of this work was to develop a CAIX-specific nanobody conjugated to IRDye800CW for molecular imaging of pre-invasive breast cancer. PROCEDURES: CAIX-specific nanobodies were selected using a modified phage display technology, conjugated site-specifically to IRDye800CW and evaluated in a xenograft breast cancer mouse model using ductal carcinoma in situ cells (DCIS). RESULTS: Specific anti-CAIX nanobodies were obtained. Administration of a CAIX-specific nanobody into mice with DCIS xenografts overexpressing CAIX showed after 2 h a mean tumor-to-normal tissue ratio (TNR) of 4.3 ± 0.6, compared to a TNR of 1.4 ± 0.2 in mice injected with the negative control nanobody R2-IR. In DCIS mice, a TNR of 1.8 ± 0.1 was obtained. Biodistribution studies demonstrated an uptake of 14.0 ± 1.1 %I.D./g in DCIS + CAIX tumors, 4.6 ± 0.8 %I.D./g in DCIS tumors, while 2.0 ± 0.2 %I.D./g was obtained with R2-IR. CONCLUSIONS: These results demonstrate the successful generation of a CAIX-specific nanobody-IRDye800CW conjugate that can be used for rapid imaging of (pre-)invasive breast cancer.

The potential of hypoxia markers as target for breast molecular imaging--a systematic review and meta-analysis of human marker expression.

BACKGROUND: Molecular imaging of breast cancer is a promising emerging technology, potentially able to improve clinical care. Valid imaging targets for molecular imaging tracer development are membrane-bound hypoxia-related proteins, expressed when tumor growth outpaces neo-angiogenesis. We performed a systematic literature review and meta-analysis of such hypoxia marker expression rates in human breast cancer to evaluate their potential as clinically relevant molecular imaging targets. METHODS: We searched MEDLINE and EMBASE for articles describing membrane-bound proteins that are related to hypoxia inducible factor 1α (HIF-1α), the key regulator of the hypoxia response. We extracted expression rates of carbonic anhydrase-IX (CAIX), glucose transporter-1 (GLUT1), C-X-C chemokine receptor type-4 (CXCR4), or insulin-like growth factor-1 receptor (IGF1R) in human breast disease, evaluated by immunohistochemistry. We pooled study results using random-effects models and applied meta-regression to identify associations with clinicopathological variables. RESULTS: Of 1,705 identified articles, 117 matched our selection criteria, totaling 30,216 immunohistochemistry results. We found substantial between-study variability in expression rates. Invasive cancer showed pooled expression rates of 35% for CAIX (95% confidence interval (CI): 26-46%), 51% for GLUT1 (CI: 40-61%), 46% for CXCR4 (CI: 33-59%), and 46% for IGF1R (CI: 35-70%). Expression rates increased with tumor grade for GLUT1, CAIX, and CXCR4 (all p < 0.001), but decreased for IGF1R (p < 0.001). GLUT1 showed the highest expression rate in grade III cancers with 58% (45-69%). CXCR4 showed the highest expression rate in small T1 tumors with 48% (CI: 28-69%), but associations with size were only significant for CAIX (p < 0.001; positive association) and IGF1R (p = 0.047; negative association). Although based on few studies, CAIX, GLUT1, and CXCR4 showed profound lower expression rates in normal breast tissue and benign breast disease (p < 0.001), and high rates in carcinoma in situ. Invasive lobular carcinoma consistently showed lower expression rates (p < 0.001). CONCLUSIONS: Our results support the potential of hypoxia-related markers as breast cancer molecular imaging targets. Although specificity is promising, combining targets would be necessary for optimal sensitivity. These data could help guide the choice of imaging targets for tracer development depending on the envisioned clinical application.

Endocytosis of EGFR requires its kinase activity and N-terminal transmembrane dimerization motif.

EGFR signaling is attenuated by endocytosis and degradation of receptor-ligand complexes in lysosomes. Endocytosis of EGFR is known to be regulated by multiple post-translational modifications. The observation that prevention of these modifications does not block endocytosis completely, suggests the involvement of other mechanism(s). Recently, receptor clustering has been suggested to induce internalization of multiple types of membrane receptors. However, the mechanism of clustering-induced internalization remains unknown. We have used biparatopic antibody fragments from llama (VHHs) to induce EGFR clustering without stimulating tyrosine kinase activity. Using this approach, we have found an essential role for the N-terminal GG4-like dimerization motif in the transmembrane domain (TMD) for clustering-induced internalization. Moreover, conventional EGF-induced receptor internalization depends exclusively on this TMD dimerization and kinase activity. Mutations in this dimerization motif eventually lead to reduced EGFR degradation and sustained signaling. We propose a novel role for the TMD dimerization motif in the negative-feedback control of EGFR. The widely conserved nature of GG4-like dimerization motifs in transmembrane proteins suggests a general role for these motifs in clustering-induced internalization.

Nuclear localization of the transcriptional coactivator YAP is associated with invasive lobular breast cancer.

BACKGROUND: Yes Associated Protein (YAP) has been implicated in the control of organ size by regulating cell proliferation and survival. YAP is a transcriptional coactivator that controls cellular responses through interaction with TEAD transcription factors in the nucleus, while its transcriptional functions are inhibited by phosphorylation-dependent translocation to the cytosol. YAP overexpression has been associated with different types of cancer, such as lung, skin, prostate, ovary and liver cancer. Recently, YAP was linked to E-cadherin-dependent regulation of contact inhibition in breast cancer cells. RESULTS: In this study we examined YAP protein expression and cellular localization in 237 cases of human invasive breast cancer by immunohistochemistry and related its expression to clinicopathological features and E-cadherin expression. We observed that invasive lobular carcinoma is characterized by higher expression levels of both nuclear and cytosolic YAP (p < 0.001). Nuclear YAP expression did not associate with other variables such as lymph node involvement, tumor grade, tumor size, mitotic activity or the molecular sub-types of invasive breast cancer. We observed that high nuclear and cytosolic YAP expression are associated with the E-cadherin deficient breast cancer subtype ILC (p < 0.001) and cell lines derived from human breast cancers and conditional mouse models of human lobular breast cancer. CONCLUSIONS: Since our data indicate that nuclear YAP localization is more common in breast cancers lacking functional adherens junctions, it suggests that YAP-mediated transcription may be involved in the development and progression of invasive lobular breast cancer.

Molecular imaging with a fluorescent antibody targeting carbonic anhydrase IX can successfully detect hypoxic ductal carcinoma in situ of the breast.

Ductal carcinoma in situ (DCIS) of the breast is difficult to remove completely during surgery as it is not palpable and can therefore require re-excision. Real-time visualization of DCIS using near-infrared fluorescent probes could help the surgeon during surgery as well as the pathologist post-operatively to distinguish the tumor from healthy tissue. As hypoxia-induced necrosis is a common phenomenon in DCIS, we investigated the molecular imaging of DCIS using a fluorescent antibody targeting a hypoxia marker, carbonic anhydrase IX (CAIX), in a preclinical mouse model. A monoclonal antibody against human CAIX was fluorescently labeled with the near-infrared dye IRDye800CW and characterized in vitro. An in vivo study was performed in SCID/Beige mice that were orthotopically transplanted with human breast cancer cells mimicking human DCIS (MCF10DCIS) and MCF10DCIS stably expressing CAIX. A clinically approved fluorescence imaging system was used to monitor probe uptake and to determine tumor-to-normal tissue ratios (TNR). Mean in vivo TNR of CAIX-transduced (CAIX+) tumors was 7.5 ± 0.5. Mean in vivo TNR of DCIS tumors with hypoxic areas reached a plateau level at 48 h after injection of 2.1 ± 0.1 (mean ± SEM) compared to 1.7 ± 0.1 in DCIS without hypoxic areas. Mean intra-operative TNR of DCIS tumors with necrotic regions was higher than that of DCIS tumors without necrotic regions 96 h after injection-2.9 ± 0.1 and 1.5 ± 0.1, respectively-while the TNR of CAIX+ tumors was 11.2 ± 1.0. Specific tumor uptake of MabCAIX-IRDye800CW was confirmed by a biodistribution assay, and immunofluorescence imaging on tumor sections showed specific uptake in hypoxic tumor regions, with higher contrast than conventional chromagen-based immunohistochemistry. Molecular fluorescence imaging with MabCAIX-IRDye800CW can be successfully used to detect hypoxic DCIS before and during surgery to facilitate radical resection. Furthermore, it allows for sensitive CAIX-specific immunofluorescence microscopy of tumor sections, thereby introducing the concept of molecular fluorescence pathology.

Loss of p120-catenin induces metastatic progression of breast cancer by inducing anoikis resistance and augmenting growth factor receptor signaling.

Metastatic breast cancer remains the chief cause of cancer-related death among women in the Western world. Although loss of cell-cell adhesion is key to breast cancer progression, little is known about the underlying mechanisms that drive tumor invasion and metastasis. Here, we show that somatic loss of p120-catenin (p120) in a conditional mouse model of noninvasive mammary carcinoma results in formation of stromal-dense tumors that resemble human metaplastic breast cancer and metastasize to lungs and lymph nodes. Loss of p120 in anchorage-dependent breast cancer cell lines strongly promoted anoikis resistance through hypersensitization of growth factor receptor (GFR) signaling. Interestingly, p120 deletion also induced secretion of inflammatory cytokines, a feature that likely underlies the formation of the prometastatic microenvironment in p120-negative mammary carcinomas. Our results establish a preclinical platform to develop tailored intervention regimens that target GFR signals to treat p120-negative metastatic breast cancers.

Analysis of expression of membrane-bound tumor markers in ductal carcinoma in situ of the breast: paving the way for molecular imaging.

PURPOSE: Achieving radicality during breast conserving surgery for pure ductal carcinoma in situ (DCIS) of the breast and invasive cancer surrounded by DCIS is challenging. Molecular imaging holds promise here, when applied as a tool for image-guided surgery of DCIS. METHODS: Tissue microarrays containing 24 pure DCIS and 63 DCIS with adjacent invasive breast cancer cases were stained by immunohistochemistry for a panel of membrane-bound targets. RESULTS: GLUT1 expression was present in 60.9%, IGF1-R in 55.2% HER2 in 28.7%, MET in 18.4%, EGFR in 16.1%, CD44v6 in 69%, carbonic anhydrase XII (CAXII) in 24.1% and Mammaglobin in 14.9% of DCIS cases. No expression differences between pure DCIS and DCIS with adjacent cancer were observed. Further, HER2 and EGFR expression were correlated with high grade DCIS (p=0.001) and CAXII with low grade DCIS (p=0.027). A putative panel containing HER2, EGFR, GLUT1 and IGF1-R had a detection rate of 90.2% for DCIS and 78.3% for adjacent breast cancer. CONCLUSIONS: We found that membrane-bound targets are more frequently expressed in DCIS than in invasive breast cancer, but that single membrane proteins are too infrequently expressed to serve as single imaging targets for the detection of DCIS. However, a panel of markers consisting of IGF1-R, CD44v6, GLUT1, EGFR, and HER2 was found to be positive in 96.3% of DICS based on marker expression in the adjacent invasive breast cancer as described earlier. This implies that detection of DCIS based on marker expression in the adjacent invasive breast cancer during breast conserving surgery should be possible with a panel of molecular imaging tracers targeting CD44v6, GLUT1, HER2, IGF1-R, and EGFR.

Expression of the RNA helicase DDX3 and the hypoxia response in breast cancer.

AIMS: DDX3 is an RNA helicase that has antiapoptotic properties, and promotes proliferation and transformation. In addition, DDX3 was shown to be a direct downstream target of HIF-1α (the master regulatory of the hypoxia response) in breast cancer cell lines. However, the relation between DDX3 and hypoxia has not been addressed in human tumors. In this paper, we studied the relation between DDX3 and the hypoxic responsive proteins in human breast cancer. METHODS AND RESULTS: DDX3 expression was investigated by immunohistochemistry in breast cancer in comparison with hypoxia related proteins HIF-1α, GLUT1, CAIX, EGFR, HER2, Akt1, FOXO4, p53, ERα, COMMD1, FER kinase, PIN1, E-cadherin, p21, p27, Transferrin receptor, FOXO3A, c-Met and Notch1. DDX3 was overexpressed in 127 of 366 breast cancer patients, and was correlated with overexpression of HIF-1α and its downstream genes CAIX and GLUT1. Moreover, DDX3 expression correlated with hypoxia-related proteins EGFR, HER2, FOXO4, ERα and c-Met in a HIF-1α dependent fashion, and with COMMD1, FER kinase, Akt1, E-cadherin, TfR and FOXO3A independent of HIF-1α. CONCLUSIONS: In invasive breast cancer, expression of DDX3 was correlated with overexpression of HIF-1α and many other hypoxia related proteins, pointing to a distinct role for DDX3 under hypoxic conditions and supporting the oncogenic role of DDX3 which could have clinical implication for current development of DDX3 inhibitors.

Differential expression of growth factor receptors and membrane-bound tumor markers for imaging in male and female breast cancer.

INTRODUCTION: Male breast cancer accounts for 0.5-1% of all breast cancers and is generally diagnosed at higher stage than female breast cancers and therefore might benefit from earlier detection and targeted therapy. Except for HER2 and EGFR, little is known about expression of growth factor receptors in male breast cancer. We therefore investigated expression profiles of growth factor receptors and membrane-bound tumor markers in male breast cancer and gynecomastia, in comparison with female breast cancer. METHODS: Tissue microarrays containing 133 male breast cancer and 32 gynecomastia cases were stained by immunohistochemistry for a panel of membrane-bound targets and compared with data on 266 female breast cancers. RESULTS: Growth factor receptors were variably expressed in 4.5% (MET) up to 38.5% (IGF1-R) of male breast cancers. Compared to female breast cancer, IGF1-R and carbonic anhydrase 12 (CAXII) were more frequently and CD44v6, MET and FGFR2 less frequently expressed in male breast cancer. Expression of EGFR, HER2, CAIX, and GLUT1 was not significantly different between male and female breast cancer. Further, 48.1% of male breast cancers expressed at least one and 18.0% expressed multiple growth factor receptors. Since individual membrane receptors are expressed in only half of male breast cancers, a panel of membrane markers will be required for molecular imaging strategies to reach sensitivity. A potential panel of markers for molecular imaging, consisting of EGFR, IGF1-R, FGFR2, CD44v6, CAXII, GLUT1, and CD44v6 was positive in 77% of male breast cancers, comparable to female breast cancers. CONCLUSIONS: Expression patterns of growth factor receptors and hypoxia membrane proteins in male breast cancer are different from female breast cancer. For molecular imaging strategies, a putative panel consisting of markers for EGFR, IGF1-R, FGFR2, GLUT1, CAXII, CD44v6 was positive in 77% of cases and might be considered for development of molecular tracers for male breast cancer.

Near-infrared fluorescence molecular imaging of ductal carcinoma in situ with CD44v6-specific antibodies in mice: a preclinical study.

PURPOSE: The purpose of this study was to develop a molecular imaging technique using tracers specific for ductal carcinoma in situ (DCIS) to improve visualization and localization of DCIS during surgery. As CD44v6 is frequently expressed in DCIS, we used near-infrared fluorescently labeled CD44v6-targeting antibodies for detection of DCIS. PROCEDURE: Mice bearing orthotopically transplanted CD44v6-positive MCF10DCIS DCIS-like tumors and CD44v6-negative MDA-MB-231 control tumors were intravenously injected with IRDye800CW conjugated to CD44v6-specific antibodies or control IgGs. Noninvasive imaging was performed for 8 days postinjection, followed by intraoperative imaging. Antibody accumulation and intratumor distribution were examined. RESULTS: Maximum accumulation of CD44v6-specific antibodies was obtained 24 h postinjection. Maximum tumor-to-background ratio for MCF10DCIS tumors was 4.5 ± 0.2, compared to 1.4 ± 0.1 (control tumors, p = 0.006), and 1.7 ± 0.1 (control IgG, p = 0.014), for 8 days postinjection. Ex vivo, tumor-to-background ratios were comparable to those obtained by intraoperative imaging. CONCLUSIONS: We show the applicability of noninvasive and intraoperative optical imaging of DCIS-like lesions in vivo using CD44v6-specific antibodies.

HIF-1α and NOTCH signaling in ductal and lobular carcinomas of the breast.

BACKGROUND: NOTCH signaling is involved in every step of metazoan development and maintenance of adult tissue homeostasis. It is frequently deregulated by mutations and overexpression in different cancer types including solid tumors such as breast cancer. Another common feature of solid tumors is hypoxia, which occurs due to defective or insufficient vascularization. Hypoxia-inducible factors (HIFs) are key regulators of the homeostatic response to low oxygen levels. HIF-1α is overexpressed in many solid tumors, including breast cancer. Hypoxia-induced stabilization of HIF transcription factors has been shown to lead to NOTCH activation in vitro in different contexts and tissues, causing differentiation arrest and induction of proliferation and migration. METHODS: Since the link between HIF-1α and NOTCH signalling has hardly been studied, we set out to closely investigate associations between the expression of HIF-1α and NOTCH pathway members in primary and metastatic human breast cancer specimens and their prognostic value. RESULTS: Co-expression of NOTCH1 intracellular domain (N1ICD) and HIF-1α was associated with a high grade and a high proliferation rate in invasive breast cancer. HIF-1α expression was low in classic, but high in pleomorphic lobular cancers, which also frequently showed stromal HIF-1α expression. NOTCH1 pathway activation was prognostically unfavorable. CONCLUSION: In breast cancer, NOTCH pathway activation appears to be associated with a poor prognosis, but NOTCH and HIF signaling do not seem to be functionally associated.

Nuclear Kaiso expression is associated with high grade and triple-negative invasive breast cancer.

Kaiso is a BTB/POZ transcription factor that is ubiquitously expressed in multiple cell types and functions as a transcriptional repressor and activator. Little is known about Kaiso expression and localization in breast cancer. Here, we have related pathological features and molecular subtypes to Kaiso expression in 477 cases of human invasive breast cancer. Nuclear Kaiso was predominantly found in invasive ductal carcinoma (IDC) (p = 0.007), while cytoplasmic Kaiso expression was linked to invasive lobular carcinoma (ILC) (p = 0.006). Although cytoplasmic Kaiso did not correlate to clinicopathological features, we found a significant correlation between nuclear Kaiso, high histological grade (p = 0.023), ERα negativity (p = 0.001), and the HER2-driven and basal/triple-negative breast cancers (p = 0.018). Interestingly, nuclear Kaiso was also abundant in BRCA1-associated breast cancer (p<0.001) and invasive breast cancer overexpressing EGFR (p = 0.019). We observed a correlation between nuclear Kaiso and membrane-localized E-cadherin and p120-catenin (p120) (p<0.01). In contrast, cytoplasmic p120 strongly correlated with loss of E-cadherin and low nuclear Kaiso (p = 0.005). We could confirm these findings in human ILC cells and cell lines derived from conditional mouse models of ILC. Moreover, we present functional data that substantiate a mechanism whereby E-cadherin controls p120-mediated relief of Kaiso-dependent gene repression. In conclusion, our data indicate that nuclear Kaiso is common in clinically aggressive ductal breast cancer, while cytoplasmic Kaiso and a p120-mediated relief of Kaiso-dependent transcriptional repression characterize ILC.

Immunophenotyping invasive breast cancer: paving the road for molecular imaging.

BACKGROUND: Mammographic population screening in The Netherlands has increased the number of breast cancer patients with small and non-palpable breast tumors. Nevertheless, mammography is not ultimately sensitive and specific for distinct subtypes. Molecular imaging with targeted tracers might increase specificity and sensitivity of detection. Because development of new tracers is labor-intensive and costly, we searched for the smallest panel of tumor membrane markers that would allow detection of the wide spectrum of invasive breast cancers. METHODS: Tissue microarrays containing 483 invasive breast cancers were stained by immunohistochemistry for a selected set of membrane proteins known to be expressed in breast cancer. RESULTS: The combination of highly tumor-specific markers glucose transporter 1 (GLUT1), epidermal growth factor receptor (EGFR), insulin-like growth factor-1 receptor (IGF1-R), human epidermal growth factor receptor 2 (HER2), hepatocyte growth factor receptor (MET), and carbonic anhydrase 9 (CAIX) 'detected' 45.5% of tumors, especially basal/triple negative and HER2-driven ductal cancers. Addition of markers with a 2-fold tumor-to-normal ratio increased the detection rate to 98%. Including only markers with >3 fold tumor-to-normal ratio (CD44v6) resulted in an 80% detection rate. The detection rate of the panel containing both tumor-specific and less tumor-specific markers was not dependent on age, tumor grade, tumor size, or lymph node status. CONCLUSIONS: In search of the minimal panel of targeted probes needed for the highest possible detection rate, we showed that 80% of all breast cancers express at least one of a panel of membrane markers (CD44v6, GLUT1, EGFR, HER2, and IGF1-R) that may therefore be suitable for molecular imaging strategies. This study thereby serves as a starting point for further development of a set of antibody-based optical tracers with a high breast cancer detection rate.

COMMD1 disrupts HIF-1alpha/beta dimerization and inhibits human tumor cell invasion.

The gene encoding COMM domain-containing 1 (COMMD1) is a prototypical member of the COMMD gene family that has been shown to inhibit both NF-kappaB- and HIF-mediated gene expression. NF-kappaB and HIF are transcription factors that have been shown to play a role in promoting tumor growth, survival, and invasion. In this study, we demonstrate that COMMD1 expression is frequently suppressed in human cancer and that decreased COMMD1 expression correlates with a more invasive tumor phenotype. We found that direct repression of COMMD1 in human cell lines led to increased tumor invasion in a chick xenograft model, while increased COMMD1 expression in mouse melanoma cells led to decreased lung metastasis in a mouse model. Decreased COMMD1 expression also correlated with increased expression of genes known to promote cancer cell invasiveness, including direct targets of HIF. Mechanistically, our studies show that COMMD1 inhibits HIF-mediated gene expression by binding directly to the amino terminus of HIF-1alpha, preventing its dimerization with HIF-1beta and subsequent DNA binding and transcriptional activation. Altogether, our findings demonstrate a role for COMMD1 in tumor invasion and provide a detailed mechanism of how this factor regulates the HIF pathway in cancer cells.