Immunomodulatory Synthetic Glycocluster Molecule Prevents Melanoma Growth In Vivo.

Triacedimannose (TADM) is a synthetic trivalent acetylated glycocluster and a transmembrane macrophage activator independent of the mannose receptor. TADM induces Th1-type immune responses and suppresses Th2-type cytokines in acute and chronic allergic inflammation models in vivo. We, therefore, wanted to test whether TADM could also facilitate anti-tumour tissue responses similar to what has been observed for the immune checkpoint inhibitors, such as anti-PD-1 and anti-CTLA-4. A syngeneic mouse melanoma model was selected since metastatic melanoma has been successfully targeted by checkpoint inhibitors in the clinic. TADM inhibited the growth of B16 mouse melanoma tumours at levels comparable to an anti-PD-1 antibody. TADM-treated tumours encompassed significantly more apoptotic cells as measured by TUNEL staining, and interferon-gamma (IFN-γ) expression was increased in the spleens of TADM-treated mice compared to untreated controls. TADM-treated mice also demonstrated increased Ly6 C low monocytes and neutrophils in the spleens. However, TADM-treated tumours showed no discernible differences in infiltrating immune cells. TADM can alone suppress the growth of melanoma tumours. TADM likely activates M1 type macrophages, type N1 neutrophils, and CD8+ and Th1 T cells, suppressing the type 2 immune response milieu of melanoma tumour with a strong type 1 immune response.

Tumor margins that lead to reoperation in breast cancer: A retrospective register study of 4,489 patients.

BACKGROUND AND OBJECTIVES: Optimal margins for ductal carcinoma in situ (DCIS) remain controversial in breast-conserving surgery (BCS) and mastectomy. We examine the association of positive margins, reoperations, DCIS and age. METHODS: A retrospective study of histopathological reports (4489 patients). Margin positivity was defined as ink on tumor for invasive carcinoma. For DCIS, we applied 2 mm anterior and side margin thresholds, and ink on tumor in the posterior margin. RESULTS: The incidence of positive side margins was 20% in BCS and 5% in mastectomies (p < 0.001). Of these patients, 68% and 14% underwent a reoperation (p < 0.001). After a positive side margin in BCS, the reoperation rates according to age groups were 74% (<49), 69% (50-64), 68% (65-79), and 42% (80+) (p = 0.013). Of BCS patients with invasive carcinoma in the side margin, 73% were reoperated on. A reoperation was performed in 70% of patients with a close (≤1 mm) DCIS side margin, compared to 43% with a wider (1.1-2 mm) margin (p = 0.002). The reoperation rates were 55% in invasive carcinoma with close DCIS, 66% in close extensive intraductal component (EIC), and 83% in close pure DCIS (p < 0.001). CONCLUSIONS: Individual assessment as opposed to rigid adherence to guidelines was used in the decision on reoperation.

Stromal interaction molecule 1 (STIM1) knock down attenuates invasion and proliferation and enhances the expression of thyroid-specific proteins in human follicular thyroid cancer cells.

Stromal interaction molecule 1 (STIM1) and the ORAI1 calcium channel mediate store-operated calcium entry (SOCE) and regulate a multitude of cellular functions. The identity and function of these proteins in thyroid cancer remain elusive. We show that STIM1 and ORAI1 expression is elevated in thyroid cancer cell lines, compared to primary thyroid cells. Knock-down of STIM1 or ORAI1 attenuated SOCE, reduced invasion, and the expression of promigratory sphingosine 1-phosphate and vascular endothelial growth factor-2 receptors in thyroid cancer ML-1 cells. Cell proliferation was attenuated in these knock-down cells due to increased G1 phase of the cell cycle and enhanced expression of cyclin-dependent kinase inhibitory proteins p21 and p27. STIM1 protein was upregulated in thyroid cancer tissue, compared to normal tissue. Downregulation of STIM1 restored expression of thyroid stimulating hormone receptor, thyroid specific proteins and increased iodine uptake. STIM1 knockdown ML-1 cells were more susceptible to chemotherapeutic drugs, and significantly reduced tumor growth in Zebrafish. Furthermore, STIM1-siRNA-loaded mesoporous polydopamine nanoparticles attenuated invasion and proliferation of ML-1 cells. Taken together, our data suggest that STIM1 is a potential diagnostic and therapeutic target for treatment of thyroid cancer.

Overexpression of Human Estrogen Biosynthetic Enzyme Hydroxysteroid (17beta) Dehydrogenase Type 1 Induces Adenomyosis-like Phenotype in Transgenic Mice.

Hydroxysteroid (17beta) dehydrogenase type 1 (HSD17B1) is an enzyme that converts estrone to estradiol, while adenomyosis is an estrogen-dependent disease with poorly understood pathophysiology. In the present study, we show that mice universally over-expressing human estrogen biosynthetic enzyme HSD17B1 (HSD17B1TG mice) present with adenomyosis phenotype, characterized by histological and molecular evaluation. The first adenomyotic changes with endometrial glands partially or fully infiltrated into the myometrium appeared at the age of 5.5 months in HSD17B1TG females and became more prominent with increasing age. Preceding the phenotype, increased myometrial smooth muscle actin positivity and increased amount of glandular myofibroblast cells were observed in HSD17B1TG uteri. This was accompanied by transcriptomic upregulation of inflammatory and estrogen signaling pathways. Further, the genes upregulated in the HSD17B1TG uterus were enriched with genes previously observed to be induced in the human adenomyotic uterus, including several genes of the NFKB pathway. A 6-week-long HSD17B1 inhibitor treatment reduced the occurrence of the adenomyotic changes by 5-fold, whereas no effect was observed in the vehicle-treated HSD17B1TG mice, suggesting that estrogen is the main upstream regulator of adenomyosis-induced uterine signaling pathways. HSD17B1 is considered as a promising drug target to inhibit estrogen-dependent growth of endometrial disorders. The present data indicate that HSD17B1 over-expression in TG mice results in adenomyotic changes reversed by HSD17B1 inhibitor treatment and HSD17B1 is, thus, a potential novel drug target for adenomyosis.

A prognostic model based on cell-cycle control predicts outcome of breast cancer patients.

BACKGROUND: A prognostic model combining biomarkers of metaphase-anaphase transition of the cell cycle was developed for invasive breast cancer. The prognostic value and clinical applicability of the model was evaluated in comparison with the routine prognosticators of invasive breast carcinoma. METHODS: The study comprised 1135 breast cancer patients with complete clinical data and up to 22-year follow-up. Regulators of metaphase-anaphase transition were detected immunohistochemically and the biomarkers with the strongest prognostic impacts were combined into a prognostic model. The prognostic value of the model was tested and evaluated in separate patient materials originating from two Finnish breast cancer centers. RESULTS: The designed model comprising immunoexpressions of Securin, Separase and Cdk1 identified 8.4-fold increased risk of breast cancer mortality (p < 0.0001). A survival difference exceeding 15 years was observed between the majority (> 75%) of patients resulting with favorable as opposed to unfavorable outcome of the model. Along with nodal status, the model showed independent prognostic impact for all breast carcinomas and for subgroups of luminal, N+ and N- disease. CONCLUSIONS: The impact of the proposed prognostic model in predicting breast cancer survival was comparable to nodal status. However, the model provided additional information in N- breast carcinoma in identifying patients with aggressive course of disease, potentially in need of adjuvant treatments. Concerning N+, in turn, the model could provide evidence for withholding chemotherapy from patients with favorable outcome.

Separase is a marker for prognosis and mitotic activity in breast cancer.

BACKGROUND: Cancer cell proliferation is a critical feature in classifying and predicting the outcome of breast carcinoma. Separase has a central role in cell cycle progression in unleashing sister-chromatids at anaphase onset. Abnormally functioning separase is known to lead to chromosomal instability. METHODS: The study comprises 349 breast carcinoma patients treated in Central Hospital of Central Finland. The prognostic value, role as a proliferation marker and regulatory interactions of separase are evaluated by immunohistochemical and double- and triple-immunofluorescence (IF) detections based on complete clinical data and >22-year follow-up of the patient material. RESULTS: In our material, abnormal separase expression predicted doubled risk of breast cancer death (P<0.001). Up to 11.3-year survival difference was observed when comparing patients with and without separase expressing cancer cell mitoses. Particularly, abnormal separase expression predicted impaired survival for luminal breast carcinoma (P<0.001, respectively). In multivariate analyses, abnormal separase expression showed independent prognostic value. The complex inhibitory interactions involving securin and cyclin B1 were investigated in double- and triple-IFs and revealed patient subgroups with aberrant regulation and expression patterns of separase. CONCLUSIONS: In our experience, separase is a promising and clinically applicable proliferation marker. Separase expression shows strong and independent prognostic value and could be developed into a biomarker for treatment decisions in breast carcinoma, particularly defining prognostic subgroups among luminal carcinomas.

Breast cancer in neurofibromatosis type 1: overrepresentation of unfavourable prognostic factors.

BACKGROUND: An increased breast cancer incidence and poor survival have been reported for women with neurofibromatosis 1 (NF1). To explain the poor survival, we aimed to link the histopathology and clinical characteristics of NF1-associated breast cancers. METHODS: The Finnish Cancer Registry and the Finnish NF Registry were cross-referenced to identify the NF1 patients with breast cancer. Archival NF1 breast cancer specimens were retrieved for histopathological typing and compared with matched controls. RESULTS: A total of 32 breast cancers were diagnosed in 1404 NF1 patients during the follow-up. Women with NF1 had an estimated lifetime risk of 18.0% for breast cancer, and this is nearly two-fold compared with that of the general Finnish female population (9.74%). The 26 successfully retrieved archival NF1 breast tumours were more often associated with unfavourable prognostic factors, such as oestrogen and progesterone receptor negativity and HER2 amplification. However, survival was worse in the NF1 group (P=0.053) even when compared with the control group matched for age, diagnosis year, gender and oestrogen receptor status. Scrutiny of The Cancer Genome Atlas data set showed that NF1 mutations and deletions were associated with similar characteristics in the breast cancers of the general population. CONCLUSIONS: These results emphasise the role of the NF1 gene in the pathogenesis of breast cancer and a need for active follow-up for breast cancer in women with NF1.

PTTG1-interacting protein (PTTG1IP/PBF) predicts breast cancer survival.

BACKGROUND: PTTG1-interacting protein (PTTG1IP) is an oncogenic protein, which participates in metaphase-anaphase transition of the cell cycle through activation of securin (PTTG1). PTTG1IP promotes the shift of securin from the cell cytoplasm to the nucleus, allowing the interaction between separase and securin. PTTG1IP overexpression has been previously observed in malignant disease, e.g. in breast carcinoma. However, the prognostic value of PTTG1IP in breast carcinoma patients has not previously been revealed. METHODS: A total of 497 breast carcinoma patients with up to 22-year follow-up were analysed for PTTG1IP and securin immunoexpression. The results were evaluated for correlations with the clinical prognosticators and patient survival. RESULTS: In our material, negative PTTG1IP immunoexpression predicted a 1.5-fold risk of breast cancer death (p = 0.02). However, adding securin immunoexpression to the analysis indicated an even stronger and independent prognostic power in the patient material (HR = 2.5, p < 0.0001). The subcellular location of securin was found with potential prognostic value also among the triple-negative breast carcinomas (n = 96, p = 0.052). CONCLUSIONS: PTTG1IP-negativity alone and in combination with high securin immunoexpression indicates a high risk of breast cancer death, resulting in up to 14-year survival difference in our material.

Inhibiting Notch Activity in Breast Cancer Stem Cells by Glucose Functionalized Nanoparticles Carrying γ-secretase Inhibitors.

Cancer stem cells (CSCs) are a challenge in cancer treatment due to their therapy resistance. We demonstrated that enhanced Notch signaling in breast cancer promotes self-renewal of CSCs that display high glycolytic activity and aggressive hormone-independent tumor growth in vivo. We took advantage of the glycolytic phenotype and the dependence on Notch activity of the CSCs and designed nanoparticles to target the CSCs. Mesoporous silica nanoparticles were functionalized with glucose moieties and loaded with a γ-secretase inhibitor, a potent interceptor of Notch signaling. Cancer cells and CSCs in vitro and in vivo efficiently internalized these particles, and particle uptake correlated with the glycolytic profile of the cells. Nanoparticle treatment of breast cancer transplants on chick embryo chorioallantoic membranes efficiently reduced the cancer stem cell population of the tumor. Our data reveal that specific CSC characteristics can be utilized in nanoparticle design to improve CSC-targeted drug delivery and therapy.

Human breast cancer cells educate macrophages toward the M2 activation status.

INTRODUCTION: The immune system plays a major role in cancer progression. In solid tumors, 5-40 % of the tumor mass consists of tumor-associated macrophages (TAMs) and there is usually a correlation between the number of TAMs and poor prognosis, depending on the tumor type. TAMs usually resemble M2 macrophages. Unlike M1-macrophages which have pro-inflammatory and anti-cancer functions, M2-macrophages are immunosuppressive, contribute to the matrix-remodeling, and hence favor tumor growth. The role of TAMs is not fully understood in breast cancer progression. METHODS: Macrophage infiltration (CD68) and activation status (HLA-DRIIα, CD163) were evaluated in a large cohort of human primary breast tumors (562 tissue microarray samples), by immunohistochemistry and scored by automated image analysis algorithms. Survival between groups was compared using the Kaplan-Meier life-table method and a Cox multivariate proportional hazards model. Macrophage education by breast cancer cells was assessed by ex vivo differentiation of peripheral blood mononuclear cells (PBMCs) in the presence or absence of breast cancer cell conditioned media (MDA-MB231, MCF-7 or T47D cell lines) and M1 or M2 inducing cytokines (respectively IFN-γ, IL-4 and IL-10). Obtained macrophages were analyzed by flow cytometry (CD14, CD16, CD64, CD86, CD200R and CD163), ELISA (IL-6, IL-8, IL-10, monocyte colony stimulating factor M-CSF) and zymography (matrix metalloproteinase 9, MMP-9). RESULTS: Clinically, we found that high numbers of CD163(+) M2-macrophages were strongly associated with fast proliferation, poor differentiation, estrogen receptor negativity and histological ductal type (p<0.001) in the studied cohort of human primary breast tumors. We demonstrated ex vivo that breast cancer cell-secreted factors modulate macrophage differentiation toward the M2 phenotype. Furthermore, the more aggressive mesenchymal-like cell line MDA-MB231, which secretes high levels of M-CSF, skews macrophages toward the more immunosuppressive M2c subtype. CONCLUSIONS: This study demonstrates that human breast cancer cells influence macrophage differentiation and that TAM differentiation status correlates with recurrence free survival, thus further emphasizing that TAMs can similarly affect therapy efficacy and patient outcome.

Hypoxia, blood flow and metabolism in squamous-cell carcinoma of the head and neck: correlations between multiple immunohistochemical parameters and PET.

BACKGROUND: The relationship between the uptake of [18F]fluoroerythronitroimidazole ([18F]FETNIM), blood flow ([15O]H2O) and 2-[18F]fluoro-2-deoxyglucose ([18F]FDG) and immunohistochemically determined biomarkers was evaluated in squamous-cell carcinomas of the head and neck (HNSCC). METHODS: [18F]FETNIM and [18F]FDG PET were performed on separate days on 15 untreated patients with HNSCC. Hypoxia imaging with [18F]FETNIM was coupled with measurement of tumor blood flow using [15O]H2O. Uptake of [18F]FETNIM was measured as tumor-to-plasma ratio (T/P) and fractional hypoxic volume (FHV), and that of [18F]FDG as standardized uptake value (SUV) and the metabolically active tumor volume (TV). Tumor biopsies were cut and stained for GLUT-1, Ki-67, p53, CD68, HIF-1α, VEGFsc-152, CD31 and apoptosis. The expression of biomarkers was correlated to PET findings and patient outcome. RESULTS: None of the PET parameters depicting hypoxia and metabolism correlated with the expression of the biomarkers on a continuous scale. When PET parameters were divided into two groups according to median values, a significant association was detected between [18F]FDG SUV and p53 expression (p =0.029) using median SUV as the cut-off. There was a significant association between tumor volume and the amount of apoptotic cells (p =0.029). The intensity of VEGF stained cells was associated with [18F]FDG SUV (p =0.036). Patient outcome was associated with tumor macrophage content (p =0.050), but not with the other biomarkers. HIF-1α correlated with GLUT-1 (rs =0.553, p =0.040) and Ki-67 with HIF-1α (rs =506, p =0.065). p53 correlated inversely with GLUT-1 (rs = -618, p =0.019) and apoptosis with Ki-67 (rs = -638, p =0.014). CONCLUSIONS: A high uptake of [18F]FDG expressed as SUV is linked to an aggressive HNSCC phenotype: the rate of apoptosis is low and the expressions of p53 and VEGF are high. None of the studied biomarkers correlated with perfusion and hypoxia as evaluated with [15O]H2O-PET and [18F]FETNIM-PET. Increased tumor metabolism evaluated with PET may thus signify an aggressive phenotype, which should be taken into account in the management of HNSCC.

ADAM12 is expressed in the tumour vasculature and mediates ectodomain shedding of several membrane-anchored endothelial proteins.

ADAM (a disintegrin and metalloproteinase) 12 is a metalloprotease implicated in cancer progression. ADAM12 can activate membrane-anchored proteins, such as sonic hedgehog, Delta-like 1 and certain epidermal growth factor receptor ligands, through a process called ectodomain shedding. We screened several membrane-anchored proteins to further dissect the substrate profile of ADAM12-mediated ectodomain shedding, and found shedding of five previously unreported substrates [Kitl1, VE-cadherin (vascular endothelial cadherin), Flk-1 (fetal liver kinase 1), Tie-2, and VCAM-1 (vascular cell adhesion molecule 1)], of which the latter four are specifically expressed by endothelial cells. We also observed that ADAM12 expression was increased in the tumour vasculature of infiltrating ductal carcinoma of the human breast as compared with little to no expression in normal breast tissue vasculature, suggesting a role for ADAM12 in tumour vessels. These results prompted us to further evaluate ADAM12-mediated shedding of two endothelial cell proteins, VE-cadherin and Tie-2. Endogenous ADAM12 expression was very low in cultured endothelial cells, but was significantly increased by cytokine stimulation. In parallel, the shed form of VE-cadherin was elevated in such cytokine-stimulated endothelial cells, and ADAM12 siRNA (small interfering RNA) knockdown reduced cytokine-induced shedding of VE-cadherin. In conclusion, the results of the present study demonstrate a role for ADAM12 in ectodomain shedding of several membrane-anchored endothelial proteins. We speculate that this process may have importance in tumour neovascularization or/and tumour cell extravasation.

Hypo- and hyperactivated Notch signaling induce a glycolytic switch through distinct mechanisms.

A switch from oxidative phosphorylation to glycolysis is frequently observed in cancer cells and is linked to tumor growth and invasion, but the underpinning molecular mechanisms controlling the switch are poorly understood. In this report we show that Notch signaling is a key regulator of cellular metabolism. Both hyper- and hypoactivated Notch induce a glycolytic phenotype in breast tumor cells, although by distinct mechanisms: hyperactivated Notch signaling leads to increased glycolysis through activation of the phosphatidylinositol 3-kinase/AKT serine/threonine kinase pathway, whereas hypoactivated Notch signaling attenuates mitochondrial activity and induces glycolysis in a p53-dependent manner. Despite the fact that cells with both hyper- and hypoactivated Notch signaling showed enhanced glycolysis, only cells with hyperactivated Notch promoted aggressive tumor growth in a xenograft mouse model. This phenomenon may be explained by that only Notch-hyperactivated, but not -hypoactivated, cells retained the capacity to switch back to oxidative phosphorylation. In conclusion, our data reveal a role for Notch in cellular energy homeostasis, and show that Notch signaling is required for metabolic flexibility.

Joint online distance learning to complement postgraduate pathology training in preparation for national board examinations.

AIMS: To meet the flexible learning needs of pathology residents preparing for national board examinations, a joint distance learning approach was developed using both asynchronous and synchronous activities with whole slide images, drawing on empirical educational research on online distance learning. METHODS: In a case study of an implementation of the designed joint distance learning approach with a geographically dispersed group of pathology residents in Finland, the participants' perceptions were measured with a 12-item questionnaire covering the value of the learning opportunity, the quality of the sociocognitive processes and their emotional engagement and social cohesion. Communication during the online session was also recorded and analysed to provide objectivity to the self-report data. RESULTS: The effectiveness of joint online learning for knowledge acquisition and preparation for national board examinations was highly rated. However, despite strong emotional engagement during synchronous activities, participants reported minimal interpersonal interaction, which was also reflected in the recordings of the online session. CONCLUSION: Using a technology integration framework and guided by the principles of self-determination theory, joint distance learning is emerging as a beneficial addition to postgraduate pathology programmes in preparation for national examinations. However, to realise the full potential of interpersonal interaction, participants should be prepared for an appropriate mindset.

Characterization of Expression and Function of the Formins FHOD1, INF2, and DAAM1 in HER2-Positive Breast Cancer.

PURPOSE: Human epidermal growth factor receptor 2 (HER2)-targeted therapies, such as trastuzumab, benefit patients with HER2-positive metastatic breast cancer; however, owing to traditional pathway activation or alternative signaling, resistance persists. Given the crucial role of the formin family in shaping the actin cytoskeleton during cancer progression, these proteins may function downstream of the HER2 signaling pathway. Our aim was to uncover the potential correlations between formins and HER2 expression using a combination of public databases, immunohistochemistry, and functional in vitro assays. METHODS: Using online databases, we identified a negative prognostic correlation between specific formins mRNA expression in HER2-positive cancers. To validate these findings at the protein level, immunohistochemistry was performed on HER2 subtype breast cancer tumors to establish the links between staining patterns and clinical characteristics. We then knocked down individual or combined formins in MDA-MB-453 and SK-BR-3 cells and investigated their effects on wound healing, transwell migration, and proliferation. Furthermore, we investigated the effects of erb-b2 receptor tyrosine kinase 2 (ERBB2)/HER2 small interfering RNA (siRNA)-mediated knockdown on the PI3K/Akt and MEK/ERK1 pathways as well as on selected formins. RESULTS: Our results revealed that correlations between INF2, FHOD1, and DAAM1 mRNA expression and ERBB2 in HER2-subtype breast cancer were associated with worse outcomes. Using immunohistochemistry, we found that high FHOD1 protein expression was linked to higher histological grades and was negatively correlated with estrogen and progesterone receptor positivity. Upon formins knockdown, we observed effects on wound healing and transwell migration, with a minimal impact on proliferation, which was evident through single and combined knockdowns in both cell lines. Notably, siRNA-mediated knockdown of HER2 affected FHOD1 and INF2 expression, along with the phosphorylated Akt/MAPK states. CONCLUSION: Our study highlights the roles of FHOD1 and INF2 as downstream effectors of the HER2/Akt and HER2/MAPK pathways, suggesting that they are potential therapeutic targets in HER2-positive breast cancer.

Securin predicts aneuploidy and survival in breast cancer.

AIMS: Securin is known to participate in maintaining chromosomal integrity during the cell cycle through regulation of metaphase-anaphase transition, DNA damage repair, and apoptosis. The aim of this study was to investigate the role of securin in aneuploidy and prognosis in human breast cancer. METHODS AND RESULTS: The study was based on 603 breast cancer patients with up to 20 years of follow-up. DNA content was determined by image cytometry on cell imprints, and securin immunohistochemistry was performed on tissue microarrays of breast cancer tissue. We show, for the first time in human breast cancer, that high-level securin expression predicts abnormal DNA content, with up to 9.8-fold odds for aneuploid DNA content (P = 0.0007). Securin also shows strong independent prognostic value for disease-specific survival, with a significant difference in survival time between patients with low-level and high-level securin expression. CONCLUSIONS: The main result of the present study is the association of aneuploidy and securin expression. According to our results, securin immunohistochemistry is also a potential new prognosticator for treatment decisions concerning breast cancer patients.

ADAM17-mediated EGFR ligand shedding directs macrophage-promoted cancer cell invasion.

Macrophages in the tumor microenvironment have a substantial impact on tumor progression. Depending on the signaling environment in the tumor, macrophages can either support or constrain tumor progression. It is therefore of therapeutic interest to identify the tumor-derived factors that control macrophage education. With this aim, we correlated the expression of A Disintegrin and Metalloproteinase (ADAM) proteases, which are key mediators of cell-cell signaling, to the expression of protumorigenic macrophage markers in human cancer cohorts. We identified ADAM17, a sheddase upregulated in many cancer types, as a protein of interest. Depletion of ADAM17 in cancer cell lines reduced the expression of several protumorigenic markers in neighboring macrophages in vitro as well as in mouse models. Moreover, ADAM17-/- educated macrophages demonstrated a reduced ability to induce cancer cell invasion. Using mass spectrometry-based proteomics and ELISA, we identified heparin-binding EGF (HB-EGF) and amphiregulin, shed by ADAM17 in the cancer cells, as the implicated molecular mediators of macrophage education. Additionally, RNA-Seq and ELISA experiments revealed that ADAM17-dependent HB-EGF ligand release induced the expression and secretion of CXCL chemokines in macrophages, which in turn stimulated cancer cell invasion. In conclusion, we provide evidence that ADAM17 mediates a paracrine EGFR-ligand-chemokine feedback loop, whereby cancer cells hijack macrophages to promote tumor progression.

GIT1 protects against breast cancer growth through negative regulation of Notch.

Hyperactive Notch signalling is frequently observed in breast cancer and correlates with poor prognosis. However, relatively few mutations in the core Notch signalling pathway have been identified in breast cancer, suggesting that as yet unknown mechanisms increase Notch activity. Here we show that increased expression levels of GIT1 correlate with high relapse-free survival in oestrogen receptor-negative (ER(-)) breast cancer patients and that GIT1 mediates negative regulation of Notch. GIT1 knockdown in ER(-) breast tumour cells increased signalling downstream of Notch and activity of aldehyde dehydrogenase, a predictor of poor clinical outcome. GIT1 interacts with the Notch intracellular domain (ICD) and influences signalling by inhibiting the cytoplasm-to-nucleus transport of the Notch ICD. In xenograft experiments, overexpression of GIT1 in ER(-) cells prevented or reduced Notch-driven tumour formation. These results identify GIT1 as a modulator of Notch signalling and a guardian against breast cancer growth.

CIP2A Interacts with TopBP1 and Drives Basal-Like Breast Cancer Tumorigenesis.

Basal-like breast cancers (BLBC) are characterized by defects in homologous recombination (HR), deficient mitotic checkpoint, and high-proliferation activity. Here, we discover CIP2A as a candidate driver of BLBC. CIP2A was essential for DNA damage-induced initiation of mouse BLBC-like mammary tumors and for survival of HR-defective BLBC cells. CIP2A was dispensable for normal mammary gland development and for unperturbed mitosis, but selectively essential for mitotic progression of DNA damaged cells. A direct interaction between CIP2A and a DNA repair scaffold protein TopBP1 was identified, and CIP2A inhibition resulted in enhanced DNA damage-induced TopBP1 and RAD51 recruitment to chromatin in mammary epithelial cells. In addition to its role in tumor initiation, and survival of BRCA-deficient cells, CIP2A also drove proliferative MYC and E2F1 signaling in basal-like triple-negative breast cancer (BL-TNBC) cells. Clinically, high CIP2A expression was associated with poor patient prognosis in BL-TNBCs but not in other breast cancer subtypes. Small-molecule reactivators of PP2A (SMAP) inhibited CIP2A transcription, phenocopied the CIP2A-deficient DNA damage response (DDR), and inhibited growth of patient-derived BLBC xenograft. In summary, these results demonstrate that CIP2A directly interacts with TopBP1 and coordinates DNA damage-induced mitotic checkpoint and proliferation, thereby driving BLBC initiation and progression. SMAPs could serve as a surrogate therapeutic strategy to inhibit the oncogenic activity of CIP2A in BLBCs. SIGNIFICANCE: These results identify CIP2A as a nongenetic driver and therapeutic target in basal-like breast cancer that regulates DNA damage-induced G2-M checkpoint and proliferative signaling.

Cargo-specific recruitment in clathrin- and dynamin-independent endocytosis.

Spatially controlled, cargo-specific endocytosis is essential for development, tissue homeostasis and cancer invasion. Unlike cargo-specific clathrin-mediated endocytosis, the clathrin- and dynamin-independent endocytic pathway (CLIC-GEEC, CG pathway) is considered a bulk internalization route for the fluid phase, glycosylated membrane proteins and lipids. While the core molecular players of CG-endocytosis have been recently defined, evidence of cargo-specific adaptors or selective uptake of proteins for the pathway are lacking. Here we identify the actin-binding protein Swiprosin-1 (Swip1, EFHD2) as a cargo-specific adaptor for CG-endocytosis. Swip1 couples active Rab21-associated integrins with key components of the CG-endocytic machinery-Arf1, IRSp53 and actin-and is critical for integrin endocytosis. Through this function, Swip1 supports integrin-dependent cancer-cell migration and invasion, and is a negative prognostic marker in breast cancer. Our results demonstrate a previously unknown cargo selectivity for the CG pathway and a role for specific adaptors in recruitment into this endocytic route.