Geometric tumor embolic budding characterizes inflammatory breast cancer.

PURPOSE: Inflammatory breast cancer (IBC) is characterized by numerous tumor emboli especially within dermal lymphatics. The explanation remains a mystery. METHODS: This study combines experimental studies with two different IBC xenografts with image algorithmic studies utilizing human tissue microarrays (TMAs) of IBC vs non-IBC cases to support a novel hypothesis to explain IBC's sina qua non signature of florid lymphovascular emboli. RESULTS: In the human TMAs, compared to tumor features like nuclear grade (size), mitosis and Ki-67 immunoreactivity which show that IBC is only modestly more proliferative with larger nuclei than non-IBC, what really sets IBC apart is the markedly greater number of tumor emboli and distinctly smaller emboli whose numbers indicate geometric or exponential differences between IBC and non-IBC. In the experimental xenograft studies, Mary-X gives rise to tight spheroids in vitro which exhibit dynamic budding into smaller daughter spheroids whereas Karen-X exhibits only loose non-budding aggregates. Furthermore Mary-X emboli also bud dramatically into smaller daughter emboli in vivo. The mechanism that regulates this involves the generation of E-cad/NTF1, a calpain-mediated cleavage 100 kDa product of 120 kDa full length membrane E-cadherin. Inhibiting this calpain-mediated cleavage of E-cadherin by blocking either the calpain site of cleavage (SC) or the site of binding (SB) with specific decapeptides that both penetrate the cell membrane and mimic either the cleavage site or the binding site on E-cadherin, inhibits the generation of E-cad/NTF1 in a dose-dependent manner, reduces spheroid compactness and decreases budding. CONCLUSION: Since E-cad/NFT1 retains the p120ctn binding site but loses the α-and ß-catenin sites, promoting its 360° distribution around the cell's membrane, the vacilating levels of this molecule trigger budding of both the spheroids as well as the emboli. Recurrent and geometric budding of parental emboli into daughter emboli then would account for the plethora of emboli seen in IBC.

A preliminary study of the probitive value of personality assessment in medical school admissions within the United States.

BACKGROUND: Allopathic medicine faces a daunting challenge of selecting the best applicants because of the very high applicant / matriculant ratio. The quality of graduates ultimately reflects the quality of medical practice. Alarming recent trends in physician burnout, misconduct and suicide raise questions of whether we are selecting the right candidates. The United States (US) lags far behind the United Kingdom (UK) and Europe in the study of non-cognitive tests in medical school admissions. Although more recently, medical schools in both the UK, Europe and the US have begun to use situational judgement tests such as the Computer-Based Assessment for Sampling Personal Characteristics (CASPer) and the situational judgement test (SJT), recently developed by the Association of American Medical Colleges (AAMC) and that these tests are, in a sense non-cognitive in nature, direct personality tests per se have not been utilized. We have historically used, in the admissions process within the US, knowledge, reasoning and exam performance, all of which are largely influenced by intelligence and also improved with practice. Personality, though also undoubtedly influenced by intelligence, is fundamentally different and subject to different kinds of measurements. METHODS: A popular personality measurement used over the past two decades within the US in business and industry, but not medical school has been the Neo Personality Inventory - Revised (NEO-PI-R) Test. This test has not been utilized regularly in allopathic medicine probably because of the paucity of exploratory retrospective and validating prospective studies. The hypothesis which we tested was whether NEO-PI-R traits exhibited consistency between two institutions and whether their measurements showed probative value in predicting academic performance. RESULTS: Our retrospective findings indicated both interinstitutional consistencies and both positive and negative predictive values for certain traits whose correlative strengths exceeded traditional premed metrics: medical college admission test (MCAT) scores, grade point average (GPA), etc. for early academic performance. CONCLUSIONS: Our exploratory studies should catalyze larger and more detailed confirmatory studies designed to validate the importance of personality traits not only in predicting early medical school performance but also later performance in one's overall medical career.

Inflammatory breast cancer: the disease, the biology, the treatment.

Inflammatory breast cancer (IBC) is a rare and aggressive form of invasive breast cancer accounting for 2.5% of all breast cancer cases. It is characterized by rapid progression, local and distant metastases, younger age of onset, and lower overall survival compared with other breast cancers. Historically, IBC is a lethal disease with less than a 5% survival rate beyond 5 years when treated with surgery or radiation therapy. Because of its rarity, IBC is often misdiagnosed as mastitis or generalized dermatitis. This review examines IBC's unique clinical presentation, pathology, epidemiology, imaging, and biology and details current multidisciplinary management of the disease, which comprises systemic therapy, surgery, and radiation therapy.

Pten in stromal fibroblasts suppresses mammary epithelial tumours.

The tumour stroma is believed to contribute to some of the most malignant characteristics of epithelial tumours. However, signalling between stromal and tumour cells is complex and remains poorly understood. Here we show that the genetic inactivation of Pten in stromal fibroblasts of mouse mammary glands accelerated the initiation, progression and malignant transformation of mammary epithelial tumours. This was associated with the massive remodelling of the extracellular matrix (ECM), innate immune cell infiltration and increased angiogenesis. Loss of Pten in stromal fibroblasts led to increased expression, phosphorylation (T72) and recruitment of Ets2 to target promoters known to be involved in these processes. Remarkably, Ets2 inactivation in Pten stroma-deleted tumours ameliorated disruption of the tumour microenvironment and was sufficient to decrease tumour growth and progression. Global gene expression profiling of mammary stromal cells identified a Pten-specific signature that was highly represented in the tumour stroma of patients with breast cancer. These findings identify the Pten-Ets2 axis as a critical stroma-specific signalling pathway that suppresses mammary epithelial tumours.

The class I HDAC inhibitor Romidepsin targets inflammatory breast cancer tumor emboli and synergizes with paclitaxel to inhibit metastasis.

Inflammatory breast cancer (IBC) is the most metastatic variant of locally advanced breast cancer. IBC has distinctive characteristics including invasion of tumor emboli into the skin and rapid disease progression. Given our previous studies suggesting that HDAC inhibitors have promise in targeting IBC, the present study revealed that the class I HDAC inhibitor Romidepsin (FK-288, Istodax; Celgene Corporation, Summit, NJ) potently induced destruction of IBC tumor emboli and lymphatic vascular architecture. associated with inhibition of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1alpha, (HIF1alpha) proteins in the Mary-X pre-clinical model of IBC. Romidepsin treatment induced clinically relevant biomarkers in including induction of acetylated Histone 3 (Ac-H3) proteins, apoptosis, and increased p21WAF1/CIP1. Romidepsin, alone and synergistically when combined with Paclitaxel, effectively eliminated both primary tumors and metastatic lesions at multiple sites formed by the SUM149 IBC cell line. This is the first report of the ability of an HDAC inhibitor to eradicate IBC tumor emboli, to destroy the integrity of lymphatic vessel architecture and to target metastasis. Furthermore, Romidepsin, in combination with a taxane, warrants evaluation as a therapeutic strategy that may effectively target the skin involvement and rapid metastasis that are hallmarks of IBC.

The virtues of the virtual medical school interview.

The COVID-19 pandemic has mandated the use of virtual interactions in medical school. Although this falls mainly in the area of didactic instruction, of necessity, it has extended to the critical Admissions Process and the Medical School Interview itself. The California University of Science and Medicine (CUSM) with their flipped classroom approach had previously entered a virtual space of instruction even before COVID-19. Because CUSM was, in a sense, already committed to 'virtual' education, in the face of the COVID-19 pandemic, CUSM focused not on what it might lose but what it might gain and what their applicants to medical school might gain with the virtual format. The COVID-19 pandemic provided a unique opportunity to initially compare the Virtual Interview with the traditional On-Campus (In-Person) Interview during the hybrid 2020 year when the COVID-19 pandemic began. The Virtual Interview was patterned after the On-Campus Interview with some modifications. The same faculty conducted both interviews. A number of inherent advantages of the Virtual Interview surfaced to these faculty interviewers based on their subjective observations and conclusions. The overall interviewee satisfaction with the Virtual Interview was very positive based on their subjective observations and conclusions. The objective data from the Virtual Interviews compared to the On-Campus Interviews in the hybrid year resulted in a greater percentage of both offers of acceptance (p = .001) and matriculations (p = .001). In order to strengthen our initial observations, we expanded our study to include 2 pre-COVID-19 years (2018, 2019) of exclusively On-Campus interviews (n = 743) and 1 additional COVID-19 year (2021) of exclusively Virtual Interviews (n = 529). In this expanded study, interviewee demographics were not confounding and the Virtual Interview gave rise to overall greater interviewee satisfaction (p = .001), a trend to greater interviewer satisfaction and a greater percentage of both offers of acceptance (p = .047) and matriculations (p = .036).

The cell of cancer origin provides the most reliable roadmap to its diagnosis, prognosis (biology) and therapy.

Cancers arise from single transformed cells from virtually every organ of the body, divide in a relatively uncontrolled manner, and metastasize widely. A search for a "magic bullet" to precisely diagnose, characterize, and ultimately treat cancer has largely failed because cancer cells do not differ significantly from their organ-specific cells of origin. Instead of searching for genomic, epigenetic, transcriptional, and translational differences between cancers and their cells of origin, we should paradoxically focus on what cancer cells have in common with their untransformed cells of origin. This redirected search will lead to improved diagnostic and therapeutic strategies where therapeutic index considerations and drug-limiting toxicities can largely be circumvented. We cite three cancer examples that illustrate this paradigm-shifting strategy: pseudomyxoma peritonei (PP), metastasis of unknown origin (cancers of unknown primary) (MUO), and cancers that arise from potentially dispensable organs (CAD). In each of these examples, the cell of cancer origin still provides the most reliable road map to its diagnosis, prognosis (biology), and therapy.

Use of constitutive and inducible oncogene-containing iPSCs as surrogates for transgenic mice to study breast oncogenesis.

BACKGROUND: Powerful constitutive and inducible transgenic / bitransgenic / tritransgenic murine models of breast cancer have been used over the past two decades to shed light on the molecular mechanisms by which the given transgenic oncogenes have interacted with other cellular genes and set in motion breast cancer initiation and progression. However, these transgenic models, as in vivo models only, are expensive and restrictive in the opportunities they provide to manipulate the experimental variables that would enable a better understanding of the molecular events related to initial transformation and the target cell being transformed. METHODS: To overcome some of these limitations, we derived oncogene-containing induced pluripotent stem cell (iPSC) clones from tail vein fibroblasts of these transgenic mice and manipulated them both in vitro and in vivo in non-transgenic background mice. We created the iPSC clones with a relatively low M.O.I, producing retroviral integrations which averaged only 1 to 2 sites per retroviral plasmid construct used. RESULTS: Most iPSC clones derived from each group displayed an essentially normal murine karyotype, strong expression of the exogenous reprogrammable genes and significant expression of characteristic endogenous murine surface stem cell markers including SSEA-1 (CD15), PECAM-1 (CD31), Ep-Cam (CD326), and Nectin (CD112), but no expression of their transgene. A majority (75%) of iPSC clones displayed a normal murine karyotype but 25% exhibited a genomically unstable karyotype. However, even these later clones exhibited stable and characteristic iPSC properties. When injected orthotopically, select iPSC clones, either constitutive or inducible, no longer expressed their exogenous pluripotency reprogramming factors but expressed their oncogenic transgene (PyVT or ErbB2) and participated in both breast ontogenesis and subsequent oncogenesis. When injected non-orthotopically or when differentiated in vitro along several different non-mammary lineages of differentiation, the iPSC clones failed to do so. Although many clones developed anticipated teratomas, select iPSC clones under the appropriate constitutive or inducible conditions exhibited both breast ontogenesis and oncogenesis through the same stages as exhibited by their transgenic murine parents and, as such, represent transgenic surrogates. CONCLUSIONS: The iPSC clones offer a number of advantages over transgenic mice including cost, the ability to manipulate and tag in vitro, and create an in vitro model of breast ontogeny and oncogenesis that can be used to gain additional insights into the differentiated status of the target cell which is susceptible to transformation. In addition, the use of these oncogene-containing iPSC clones can be used in chemopreventive studies of breast cancer.

Regulation of breast cancer oncogenesis by the cell of origin's differentiation state.

Human breast cancer which affects 1/8 women is rare at a cellular level. Even in the setting of germline BRCA1/BRCA2, which is present in all breast cells, solitary cancers or cancers arising at only several foci occur. The overwhelming majority of breast cells (109-1012 cells) resist transformation. Our hypothesis to explain this rareness of transformation is that mammary oncogenesis is regulated by the cell of origin's critical window of differentiation so that target cells outside of this window cannot transform. Our novel hypothesis differs from both the multi-hit theory of carcinogenesis and the stem/progenitor cell compartmental theory of tumorigenesis and utilizes two well established murine transgenic models of breast oncogenesis, the FVB/N-Tg (MMTV-PyVT)634Mul/J and the FVB-Tg (MMTV-ErbB2) NK1Mul/J. Tail vein fibroblasts from each of these transgenics were used to generate iPSCs. When select clones were injected into cleared mammary fat pads, but not into non-orthotopic sites of background mice, they exhibited mammary ontogenesis and oncogenesis with the expression of their respective transgenes. iPSC clones, when differentiated along different non-mammary lineages in vitro, were also not able to exhibit either mammary ontogenesis or oncogenesis in vivo. Therefore, in vitro and in vivo regulation of differentiation is an important determinant of breast cancer oncogenesis.

Why is cancer so common a disease in people yet so rare at a cellular level?

Cancers are common diseases in people and yet, on a cellular level, are quite rare. The vast majority of both sporadic, spontaneous cancers and inherited germline cancers arise in single foci from singly transformed cells despite the fact that, in the former, carcinogenic factors bathe fields of millions of potential target cells and, in the latter, the predisposing germline mutations are present in every cell of a given organ and, in fact, every cell of the body. Although the multi-hit theory of carcinogenesis has been invoked to explain such things as cancer latency, which is the period between cancer initiation and emergence and the cancer-aging relationship where an accumulation of "hits" over a period of time are necessary for cancer emergence, the multi-hit theory falls short in explaining the rareness of transformation at a cellular level. This is so because many cancers are not due to multiple hits, and even for those that are, it would be expected that many cells would be exposed to those factors inducing the hits. Although the tumor stem/progenitor cell compartmental theory of tumorigenesis characterizes a tumor compartment that is capable of self-renewal and multipotency, accounting for cancer relapses and recurrences, this compartmental theory alone cannot account for the rareness of initial transformation at a cellular level as the cancer stem/progenitor cell compartment is already transformed and considerable in size. This study advances a different and novel hypothesis that oncogenesis is regulated and ultimately determined by a cell of origin's critical state of differentiation. Before and after this critical state of differentiation has been reached, target cells cannot transform and give rise to cancer even when they receive the necessary carcinogenic insults or have the requisite transforming tumor suppressor genes or oncogenes. As support for this hypothesis, the study cites preliminary evidence using oncogene-containing transgenic mice that develop mammary carcinomas, to derive tail vein fibroblasts converted to iPSCs which, when left undifferentiated, and injected into the cleared fat pads of non-transgenic background mice give rise to mammary gland ontogeny and mammary gland carcinogenesis. However, when first differentiated in vitro into multiply different non-mammary lineages prior to injection, they fail to do so. The hypothesis has widespread implications for chemopreventive strategies.

The lymphovascular embolus of inflammatory breast cancer expresses a stem cell-like phenotype.

Inflammatory breast carcinoma (IBC) is a particularly lethal form of breast cancer characterized by exaggerated lymphovascular invasion, which is a phenotype recapitulated in our human xenograft MARY-X. MARY-X generated spheroids in vitro that resemble the embryonal blastocyst. Because of the resemblance of the spheroids to the embryonal blastocyst and their resistance to traditional chemotherapy/radiotherapy, we hypothesized that the spheroids expressed a stem cell-like phenotype. MARY-X spheroids expressed embryonal stem cell markers including stellar, rex-1, nestin, H19, and potent transcriptional factors, oct-4, nanog, and sox-2, which are associated with stem cell self-renewal and developmental potential. Most importantly, MARY-X spheroids expressed a cancer stem cell profile characterized by CD44(+)/CD24(-/low), ALDH1, and most uniquely, CD133. A significant percentage of single cells of MARY-X exhibited distinct proliferative and morphogenic potencies in vitro. As few as 100 cells derived from single-cell clonogenic expansion were tumorigenic with recapitulation of the IBC phenotype. Prototype stem cell signaling pathways such as notch3 were active in MARY-X. The stem cell phenotype exhibited by MARY-X also was exhibited by the lymphovascular emboli of human IBC cases independent of their molecular subtype. This stem cell-like phenotype may contribute to the aggressive nature of IBC but also may lend itself to selective targeting.

Norepinephrine upregulates VEGF, IL-8, and IL-6 expression in human melanoma tumor cell lines: implications for stress-related enhancement of tumor progression.

Studies suggest that stress can be a co-factor for the initiation and progression of cancer. The catecholamine stress hormone, norepinephrine (NE), may influence tumor progression by modulating the expression of factors implicated in angiogenesis and metastasis. The goal of this study was to examine the influence of NE on the expression of VEGF, IL-8, and IL-6 by the human melanoma cell lines, C8161, 1174MEL, and Me18105. Cells were treated with NE and levels of VEGF, IL-8, and IL-6 were measured using ELISA and real-time PCR. The expression of beta-adrenergic receptors (beta-ARs) mRNA and protein were also assessed. Finally, immunohistochemistry was utilized to examine the presence of beta1- and beta2-AR in primary and metastatic human melanoma biopsies. We show that NE treatment upregulated production of VEGF, IL-8, and IL-6 in C8161 cells and to a lesser extent 1174MEL and Me18105 cells. The upregulation was associated with induced gene expression. The effect on C8161 cells was mediated by both beta1- and beta2-ARs. Furthermore, 18 of 20 melanoma biopsies examined expressed beta2-AR while 14 of 20 melanoma biopsies expressed beta1-AR. Our data support the hypothesis that NE can stimulate the aggressive potential of melanoma tumor cells, in part, by inducing the production VEGF, IL-8, and IL-6. This line of research further suggests that interventions targeting components of the activated sympathetic-adrenal medullary (SAM) axis, or the utilization of beta-AR blocking agents, may represent new strategies for slowing down the progression of malignant disease and improving cancer patients' quality of life.

ERalpha suppresses slug expression directly by transcriptional repression.

Two of the most common signalling pathways in breast cancer are the ER (oestrogen receptor) ligand activation pathway and the E-cadherin snai1 slug EMT (epithelial-mesenchymal transition) pathway. Although these pathways have been thought to interact indirectly, the present study is the first to observe direct interactions between these pathways that involves the regulation of slug expression. Specifically we report that ligand-activated ERalpha suppressed slug expression directly by repression of transcription and that knockdown of ERalpha with RNA interference increased slug expression. More specifically, slug expression was down-regulated in ERalpha-negative MDA-MB-468 cells transfected with ERalpha after treatment with E2 (17beta-oestradiol). The down-regulation of slug in the ERalpha-positive MCF-7 cell line was mediated by direct repression of slug transcription by the formation of a co-repressor complex involving ligand-activated ERalpha protein, HDAC1 (histone deacetylase 1) and N-CoR (nuclear receptor co-repressor). This finding was confirmed by sequential ChIP (chromatin immunoprecipitation) studies. In the MCF-7 cell line, slug expression normally was low. In addition, knockdown of ERalpha with RNA interference in this cell line increased slug expression. This effect could be partially reversed by treatment of the cells with E2. The efficacy of the effect of ERalpha on slug repression was dependent on the overall level of ERalpha. These observations confirmed that slug was an E2-responsive gene.

Nuclear transport of cancer extracellular vesicle-derived biomaterials through nuclear envelope invagination-associated late endosomes.

Extracellular membrane vesicles (EVs) function as vehicles of intercellular communication, but how the biomaterials they carry reach the target site in recipient cells is an open question. We report that subdomains of Rab7+ late endosomes and nuclear envelope invaginations come together to create a sub-nuclear compartment, where biomaterials associated with CD9+ EVs are delivered. EV-derived biomaterials were also found in the nuclei of host cells. The inhibition of nuclear import and export pathways abrogated the nuclear localization of EV-derived biomaterials or led to their accumulation therein, respectively, suggesting that their translocation is dependent on nuclear pores. Nuclear envelope invagination-associated late endosomes were observed in ex vivo biopsies in both breast carcinoma and associated stromal cells. The transcriptome of stromal cells exposed to cancer cell-derived CD9+ EVs revealed that the regulation of eleven genes, notably those involved in inflammation, relies on the nuclear translocation of EV-derived biomaterials. Our findings uncover a new cellular pathway used by EVs to reach nuclear compartment.

Comparative oncological studies of feline bronchioloalveolar lung carcinoma, its derived cell line and xenograft.

Although certain neoplasms are unique to man, others occur across species. One such neoplasm is bronchioloalveolar lung carcinoma (BAC), a neoplasm of the Type II pneumocyte that affects humans, sheep, and small animals (dogs and cats). Human BAC occurs largely in nonsmokers. Sheep BAC is caused by the jaagsiekte retrovirus and is endemic and contagious. Feline BAC is neither endemic nor contagious and occurs sporadically and spontaneously in older purebred cats. In these respects, feline BAC is more closely similar to human BAC than sheep BAC (jaagsiekte) is. To study feline BAC further, we established the first immortal cell line (SPARKY) and transplantable scid mouse xenograft (Sparky-X) from a malignant pleural effusion of a 12-year-old Persian male with autopsy-confirmed BAC. SPARKY exhibited a Type II pneumocyte phenotype characterized by surfactant and thyroid-transcription factor-1 immunoreactivities and lamellar bodies. SPARKY's karyotype was aneuploid (66 chromosomes: 38, normal cat) and showed evidence of genomic instability analogous to human lung cancers. p53 showed a homozygous G to T transversion at codon 167, the feline equivalent of human codon 175, one of the many hot spots mutated in the lung cancers of smokers. H-ras and K-ras were not altered. By reverse transcription-PCR, SPARKY lacked expression of retroviral JSRVgag transcripts that were present in the lungs of sheep BAC (jaagsiekte). Unlike human BAC xenografts, SPARKY-X retained its unique lepidic BAC growth pattern even though it was grown in murine s.c. tissues. This property may be related to the ability of SPARKY-X to up-regulate its surfactant genes (SP-A, SP-B, and SP-D). These studies of feline BAC may allow insights into the human disease that are not possible by studying human BAC directly.

Analogies Between Cancer-Derived Extracellular Vesicles and Enveloped Viruses with an Emphasis on Human Breast Cancer.

PURPOSE OF REVIEW: Cancer cells utilize extracellular vesicles (EVs) as a means of transferring oncogenic proteins and nucleic acids to other cells to enhance the growth and spread of the tumor. There is an unexpected amount of similarities between these small, membrane-bound particles and enveloped virions, including protein content, physical characteristics (i.e., size and morphology), and mechanisms of entry and exit into target cells. RECENT FINDINGS: This review describes the attributes shared by both cancer-derived EVs, with an emphasis on breast cancer-derived EVs, and enveloped viral particles and discusses the methods by which virions can utilize the EV pathway as a means of transferring viral material and oncogenes to host cells. Additionally, the possible links between human papilloma virus and its influence on the miRNA content of breast cancer-derived EVs are examined. SUMMARY: The rapidly growing field of EVs is allowing investigators from different disciplines to enter uncharted territory. The study of the emerging similarities between cancer-derived EVs and enveloped virions may lead to novel important scientific discoveries.

Cooperative role of E-cadherin and sialyl-Lewis X/A-deficient MUC1 in the passive dissemination of tumor emboli in inflammatory breast carcinoma.

Inflammatory breast carcinoma (IBC) is characterized by florid tumor emboli within lymphovascular spaces termed lymphovascular invasion (LVI). Using a human-scid model of IBC (MARY-X), we have demonstrated using retrovirally-mediated dominant-negative E-cadherin mutant approaches (H-2K(d)-E-cad), that the tumor cell embolus (IBC spheroid) forms on the basis of an intact and overexpressed E-cadherin/alpha, beta-catenin axis which mediates tumor cell-tumor cell adhesion analogous to the embryonic blastocyst and accounts for the compactness of the embolus. The tumor cell embolus (IBC spheroid), in contrast, fails to bind the surrounding vascular endothelial cells both in vitro and in vivo because of markedly decreased sialyl-Lewis X/A carbohydrate ligand-binding epitopes on its overexpressed MUC1 which are necessary for binding endothelial cell E-selectin. This tumor cell-endothelial cell aversion further contributes to the compactness of the IBC spheroid and its passivity in metastasis dissemination. This passivity is manifested by a dramatic increase in metastatic pulmonary emboli following palpation of the primary tumor. In assessing this passivity of metastatic dissemination, we compared the effects of palpation on MARY-X with the effects of palpation on a derived dominant-negative E-cadherin mutant (H-2K(d)-E-cad), as well as other well known human tumoral xenografts exhibiting no (MCF-7, T47D), low (MDA-MB-231, MDA-MB-468) or high (C8161, M24(met)) levels of spontaneous metastasis but no LVI. Palpation of each xenograft similarly increased intratumoral pressure by 200% (10-->30 mmHg) but dramatically increased the numbers and sizes of pulmonary metastases 10-100-fold (P<0.001) only in MARY-X. The mechanism of this effect was through an immediate post-palpation release of circulating tumor emboli detected 2-3 min after palpation (P<0.01) by human cytokeratin 19 RT-PCR of extracted RNA from 300 microl of murine blood. Although circulating human tumor cell-derived growth factors (IGF-I, IGF-II, TGF-alpha and TGF-beta) and angiogenic factors (VEGF and bFGF) were detected by ELISA in murine serum of MARY-X, palpation did not further increase the circulating levels of these factors (P>0.1). Our findings support the cooperative role of E-cadherin and sialyl-Lewis X/A-deficient MUC1 in the passive dissemination of tumor emboli in IBC.

Breast Cancer-Derived Extracellular Vesicles: Characterization and Contribution to the Metastatic Phenotype.

The study of extracellular vesicles (EVs) in cancer progression is a complex and rapidly evolving field. Whole categories of cellular interactions in cancer which were originally presumed to be due solely to soluble secreted molecules have now evolved to include membrane-enclosed extracellular vesicles (EVs), which include both exosomes and shed microvesicles (MVs), and can contain many of the same molecules as those secreted in soluble form but many different molecules as well. EVs released by cancer cells can transfer mRNA, miRNA, and proteins to different recipient cells within the tumor microenvironment, in both an autocrine and paracrine manner, causing a significant impact on signaling pathways, mRNA transcription, and protein expression. The transfer of EVs to target cells, in turn, supports cancer growth, immunosuppression, and metastasis formation. This review focuses exclusively on breast cancer EVs with an emphasis on breast cancer-derived exosomes, keeping in mind that breast cancer-derived EVs share some common physical properties with EVs of other cancers.