Organ specificity of tumor metastasis: role of preferential adhesion, invasion and growth of malignant cells at specific secondary sites

Biomarkers of minimal residual disease and treatment

Minimal residual disease (MRD) has been defined as a very small numbers of cancer cells that remain in the body after curative treatment. Its presence or absence will ultimately determine prognosis. With the introduction of new technologies the presence of MRD in patients with solid tumours can be detected and characterized. As MRD predicts future relapse, be it early or late treatment failure, in an otherwise asymptomatic patient its treatment and when to start treatment remains to be determined. Thus the concepts of personalized medicine using different biomarkers to classify the biological properties of MRD maybe come possible. Based on this determinations it may be possible to use targeted therapies rather than all patients with the same type of cancer receiving a standard treatment. However, it is important to understand the limitations of the different technologies, what these techniques are detecting and how they may help in the treatment of patients with cancer. The majority of published studies are in patients with metastatic cancer and there are few reports in patients with MRD. In this chapter the concept of MRD, the methods used to detect it and what treatments may be effective based on the biological characteristics of the tumour cells as determined by different biomarkers is reviewed. MRD depends on the phenotypic properties of the tumour cells to survive in their new environment and the anti-tumour immune response. This is a dynamic process and changes with time in the wake of immunosuppression caused by the tumour cells and/or the effects of treatment to select resistant tumour cells. With the use of biomarkers to typify the characteristics of MRD and the development of new drugs a personalized treatment can be designed rather than all patients given the same treatment. Patients who are initially negative for MRD may not require further treatment with liquid biopsies used to monitor the patients during follow-up in order to detect those patients who may become MRD positive. The liquid biopsy used during the follow up of MRD positive patients can be used to detect changes in the biological properties of the tumour cells and thus may need treatment changes to overcome tumour cell resistance.

Bj-PRO-10c, as an allosteric regulator of argininosuccinate synthase, is a potential therapy for neuroblastoma metastasis

Cancer is a global public health issue. Neuroblastoma (NB) originates from any tissue of the sympathetic nervous system, and the most affected site is the abdomen. The adrenal gland is the primary site in 38% of cases. Approximately 50% of patients have metastatic disease at diagnosis, and bone marrow is often affected. Metastatic disease is characterized by the spreading of cancer cells that are frequently resistant to chemotherapy and radiotherapy from the primary tumor to other specific parts of the body and is responsible for 90% of cancer-related deaths. Increasing evidence has indicated that nitric oxide (NO) signaling is implicated in the pathophysiology of many types of cancer, particularly in tumorigenesis and cancer progression. However, the effect of NO on metastasis cannot be easily classified as prometastatic or antimetastatic. An understanding at the molecular level of the role of NO in cancer will have profound therapeutic implications for the diagnosis and treatment of disease. Here, the proline-rich decapeptide isolated from Bothrops jararaca venom (Bj-PRO-10c) that enhances and sustains the generation of NO was used to unravel the role of metabolic NO in steps of metastasis. Bj-PRO-10c showed an antimetastatic effect, mainly by interfering with actin cytoskeleton rearrangement, controlling cell proliferation, and decreasing the seeding efficiency of NB in metastatic niches. Therefore, we proposed that an approach for controlled NO induction with the right molecular strategies can hopefully inhibit metastasis and increase the lifespan of NB patients.

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Chick Embryo Experimental Platform for Micrometastases Research in a 3D Tissue Engineering Model: Cancer Biology, Drug Development, and Nanotechnology Applications

Colonization of distant organs by tumor cells is a critical step of cancer progression. The initial avascular stage of this process (micrometastasis) remains almost inaccessible to study due to the lack of relevant experimental approaches. Herein, we introduce an in vitro/in vivo model of organ-specific micrometastases of triple-negative breast cancer (TNBC) that is fully implemented in a cost-efficient chick embryo (CE) experimental platform. The model was built as three-dimensional (3D) tissue engineering constructs (TECs) combining human MDA-MB-231 cells and decellularized CE organ-specific scaffolds. TNBC cells colonized CE organ-specific scaffolds in 2–3 weeks, forming tissue-like structures. The feasibility of this methodology for basic cancer research, drug development, and nanomedicine was demonstrated on a model of hepatic micrometastasis of TNBC. We revealed that MDA-MB-231 differentially colonize parenchymal and stromal compartments of the liver-specific extracellular matrix (LS-ECM) and become more resistant to the treatment with molecular doxorubicin (Dox) and Dox-loaded mesoporous silica nanoparticles than in monolayer cultures. When grafted on CE chorioallantoic membrane, LS-ECM-based TECs induced angiogenic switch. These findings may have important implications for the diagnosis and treatment of TNBC. The methodology established here is scalable and adaptable for pharmacological testing and cancer biology research of various metastatic and primary tumors.

Sex-Based Differences in the Tumor Microenvironment

Cancers are heterogeneous multifactorial diseases consisting of a major public health issue worldwide. Sex disparities are evidenced in cancer incidence, mortality, expression of prognosis factor, response to treatment, and survival. For both sexes, an interplay of intrinsic and environmental factors influences cancer cells and tumor microenvironment (TME) components. The TME cumulates both supportive and communicative functions, contributing to cancer development, progression, and metastasis dissemination. The frontline topics of this chapter are focused on the contribution of sex, via steroid hormones, such as estrogens and androgens, on the following components of the TME: cancer-associated fibroblasts (CAFs), extracellular matrix (ECM), blood and lymphatic endothelial cells, and immunity/inflammatory system.

Chick fetal organ spheroids as a model to study development and disease

BACKGROUND

Organ culture models have been used over the past few decades to study development and disease. The in vitro three-dimensional (3D) culture system of organoids is well known, however, these 3D systems are both costly and difficult to culture and maintain. As such, less expensive, faster and less complex methods to maintain 3D cell culture models would complement the use of organoids. Chick embryos have been used as a model to study human biology for centuries, with many fundamental discoveries as a result. These include cell type induction, cell competence, plasticity and contact inhibition, which indicates the relevance of using chick embryos when studying developmental biology and disease mechanisms.

RESULTS

Here, we present an updated protocol that enables time efficient, cost effective and long-term expansion of fetal organ spheroids (FOSs) from chick embryos. Utilizing this protocol, we generated FOSs in an anchorage-independent growth pattern from seven different organs, including brain, lung, heart, liver, stomach, intestine and epidermis. These three-dimensional (3D) structures recapitulate many cellular and structural aspects of their in vivo counterpart organs and serve as a useful developmental model. In addition, we show a functional application of FOSs to analyze cell-cell interaction and cell invasion patterns as observed in cancer.

CONCLUSION

The establishment of a broad ranging and highly effective method to generate FOSs from different organs was successful in terms of the formation of healthy, proliferating 3D organ spheroids that exhibited organ-like characteristics. Potential applications of chick FOSs are their use in studies of cell-to-cell contact, cell fusion and tumor invasion under defined conditions. Future studies will reveal whether chick FOSs also can be applicable in scientific areas such as viral infections, drug screening, cancer diagnostics and/or tissue engineering.

Site-specific metastasis: A cooperation between cancer cells and the metastatic microenvironment

The conclusion derived from the information provided in this review is that disseminating tumor cells (DTC) collaborate with the microenvironment of a future metastatic organ site in the establishment of organ‐specific metastasis. We review the basic principles of site‐specific metastasis and the contribution of the cross talk between DTC and the microenvironment of metastatic sites (metastatic microenvironment [MME]) to the establishment of the organ‐specific premetastatic niche; the targeted migration of DTC to the endothelium of the future organ‐specific metastasis; the transmigration of DTC to this site and the seeding and colonization of DTC in their future MME. We also discuss the role played by DTC‐MME interactions on tumor dormancy and on the differential response of tumor cells residing in different MMEs to antitumor therapy. Finally, we summarize some studies dealing with the effects of the MME on a unique site‐specific metastasis—brain metastasis.

Observations on Solitary Versus Multiple Isolated Pancreatic Metastases of Renal Cell Carcinoma: Another Indication of a Seed and Soil Mechanism?

Isolated pancreas metastases are a rare type of metastasis of renal cell carcinoma, characterized by the presence of pancreatic metastases, while all other organs remain unaffected. In a previous study, we determined arguments from the literature which (a) indicate a systemic-haematogenic metastasis route (uniform distribution of the metastases across the pancreas and independence of the metastatic localization in the pancreas of the side of the renal carcinoma); and (b) postulate a high impact of a seed and soil mechanism (SSM) on isolated pancreatic metastasis of renal cell carcinoma (isPM) as an explanation for exclusive pancreatic metastases, despite a systemic haematogenous tumor cell embolization. The objective of the study presented was to search for further arguments in favor of an SSM with isPM. For that purpose, the factor's histology, grading, and singular/multiple pancreas metastases were analyzed on the basis of 814 observations published up to 2018. While histology and grading allowed for no conclusions regarding the importance of an SSM, the comparison of singular/multiple pancreas metastases produced arguments in favor of an SSM: 1. The multiple pancreas metastases observed in 38.1% prove that multiple tumor cell embolisms occur with isPM, the exclusive "maturation" of which in the pancreas requires an SSM; 2. The survival rates (SVR), which are consistent with singular and multiple pancreas metastases (despite the higher total tumor load with the latter), prove that the metastasized tumor cells are not able to survive in all other organs because of an SSM, which results in identical SVR when the pancreatic foci are treated adequately.

Defining the Hallmarks of Metastasis

Metastasis is the primary cause of cancer morbidity and mortality. The process involves a complex interplay between intrinsic tumor cell properties as well as interactions between cancer cells and multiple microenvironments. The outcome is the development of a nearby or distant discontiguous secondary mass. To successfully disseminate, metastatic cells acquire properties in addition to those necessary to become neoplastic. Heterogeneity in mechanisms involved, routes of dissemination, redundancy of molecular pathways that can be utilized, and the ability to piggyback on the actions of surrounding stromal cells makes defining the hallmarks of metastasis extraordinarily challenging. Nonetheless, this review identifies four distinguishing features that are required: motility and invasion, ability to modulate the secondary site or local microenvironments, plasticity, and ability to colonize secondary tissues. By defining these first principles of metastasis, we provide the means for focusing efforts on the aspects of metastasis that will improve patient outcomes.

Ex-Vivo Model Systems of Cancer-Bone Cell Interactions

This chapter elaborates on the state-of-the-art experimental procedures utilized in ex-vivo model systems of cancer-bone cell interactions under "static and dynamic" culture conditions and their potential use to understand cellular and molecular mechanisms as well as drug testing and discovery. An additional focus of this chapter is to provide details of how to incorporate varying oxygen tension, viz., hypoxic, normoxic, and hyperoxic, in such studies and regulate the bone biology toward dissociation of the bone remodeling stages to achieve only "bone resorption" or "bone formation" individually.

[Stromal cell-derived factor-1 inducing metastasis squamous cell carcinoma of head and neck induced via integrin ανβ3-CXC chemokine receptor 4/7 biological axis]

OBJECTIVE

To observe the influence of LM609/AMD3100/CCX754 on chemotactic capability, cytoskeleton, and expression of integrin ανβ3 protein of squamous cell carcinoma of head and neck (SCCHN) cell line PCI-13 induced by stromal cell-derived factor-1 (SDF-1) in vitro.

METHODS

Migration assays, flow cytometry and immunofluorescence were used to observe the effects of SDF-1, LM609, AMD3100 and CCX754 on the migration, cytoskeleton and the expression of integrin ανβ3 protein in PCI-13 cell lines.

RESULTS

SDF-1 favored PCI-13 cell migration, pseudopod formation, and activities of integrin ανβ3 phosphorylation. LM609, AMD3100, and CCX754 blocked all these effects.

CONCLUSIONS

SDF-1 can induce metastatic SCCHN by integrin ανβ3-CXC chemokine receptor (CXCR) 4/CXCR7 axi. LM609, AMD3100, and CCX754 and can reduce the regulation of SDF-1 on SCCHN activity.

Metastasis to the extraocular muscles: a case report, literature review and pooled data analysis

Metastasis to the extraocular muscles (EOM) is rare. The existing literature comprises only of isolated case reports therefore a summative description of these lesions is lacking. This study presents a case of bilateral rectus muscle metastasis from malignant melanoma. Furthermore a literature review and pooled data analysis is undertaken with 43 articles encompassing 77 patients and 101 eyes. Mean age was 53 years, 54% were male, 66% had unilateral involvement and 34% had bilateral involvement. The primary malignancies were melanoma (n = 17, 22%), breast (n = 15, 15%) and carcinoid (n = 11, 14%). A single muscle was involved in 56 eyes (67%) and multiple muscles in 27 eyes (33%). Lateral rectus was most commonly affected (n = 44, 53%). Presenting symptoms included restricted eye movements (n = 48, 62%), proptosis (n = 45, 58%), diplopia (n = 27, 35%) and pain (n = 18, 23%). Scattered case reports have previously made it difficult to characterise this phenomenon thus a pooled data analysis is presented.

Isolated pancreatic metastases from renal cell carcinoma: an outcome of a special metastatic pathway or of specific tumor cell selection?

Isolated pancreatic metastases (isPM) are a rare metastasizing pattern in the natural history of renal cell cancer. Their clinical hallmark is that they are confined to a single organ, the pancreas, while all other organs are unaffected for a long time. Almost all workers in the field suggested that mechanical tumor cell propagation to the pancreas may be the mechanism underlying this metastasizing pattern. In 2006 our group, by contrast, proposed an alternative mechanism, i.e. a special affinity of the tumor cells for the pancreas. In the present study an attempt was made to shed more light on the settlement of isPM by reviewing recent literature data. 666 observations of isPM reported in the literature were reviewed. The analyses showed that local lymphatic spread does not play a major role because the lymphatic system is, in general, rarely involved in isPM. This also applies to a local venous spread, because the site of pancreatic metastases is independent of the side affected by the primary renal cancer. But the results are compatible with a systemic metastatic pathway. That metastases in other organs, which would be expected given a systemic spread, are absent can plausibly be explained by a seed and soil mechanism: only the pancreas offers the tumor cell emboli an environment which is conducive to the growth of clinically manifest metastases, while settlement of metastatic tumor cells is prevented in all other organs.

Mass spectrometry based identification of galectin-3 interacting proteins potentially involved in lung melanoma metastasis

Adhesive interactions between molecules on tumor cells and those on target organs play a key role in organ specific metastasis. Poly-N-acetyl-lactosamine (polyLacNAc) substituted N-oligosaccharides on melanoma cell surface glycoproteins promote lung specific metastasis via galectin-3 by facilitating their arrest and extravasation. This study reports the identification and characterization of galectin-3 interacting proteins using a combination of galectin-3 sepharose affinity and leucoagglutinating phytohemagglutinin (L-PHA) columns. A total of 83 proteins were identified as galectin-3 interacting glycoproteins, of which 35 were constituents of the L-PHA bound fraction, suggesting that these proteins carry polyLacNAc substituted β1,6 branched N-glycans. The identities of some of these proteins, like LAMP-1, LAMP-3, basigin, embigin, and α5 and β1 Integrin, have been confirmed by western blotting, and functional relevance with respect to metastatic properties has been established.

A history of exploring cancer in context

The concept that progression of cancer is regulated by interactions of cancer cells with their microenvironment was postulated by Stephen Paget over a century ago. Contemporary tumour microenvironment (TME) research focuses on the identification of tumour-interacting microenvironmental constituents, such as resident or infiltrating non-tumour cells, soluble factors and extracellular matrix components, and the large variety of mechanisms by which these constituents regulate and shape the malignant phenotype of tumour cells. In this Timeline article, we review the developmental phases of the TME paradigm since its initial description. While illuminating controversies, we discuss the importance of interactions between various microenvironmental components and tumour cells and provide an overview and assessment of therapeutic opportunities and modalities by which the TME can be targeted.

Site-specific expression of amine oxidases in breast cancer metastases

We aimed to evaluate the expression of amine oxidase-related proteins in metastatic breast cancer tissue and determine its clinical implication. A tissue microarray was constructed from a total of 126 metastatic breast tumors (31 bone metastases (24.6%), 36 brain metastases (28.6%), 11 liver metastases (8.7%), and 48 lung metastases (38.1%)). Immunohistochemical staining for amine oxidase-related proteins (lysyl oxidase, diamine oxidase, and monoamine oxidase A and B) was performed. In metastatic breast cancer tissue, lysyl oxidase ( p = 0.001), tumoral diamine oxidase ( p = 0.003), stromal diamine oxidase ( p = 0.047), and stromal monoamine oxidase B ( p = 0.002) were differentially expressed in different metastatic sites. Bone metastases showed low expression of lysyl oxidase, tumoral diamine oxidase, and stromal diamine oxidase. We observed high expression of lysyl oxidase in brain metastases, tumoral diamine oxidase in liver metastases, stromal diamine oxidase in lung metastases, and stromal monoamine oxidase B in bone metastases. Lysyl oxidase positivity was associated with progesterone receptor negativity ( p = 0.001), and monoamine oxidase A positivity was associated with human epidermal growth factor receptor-2 negativity ( p = 0.003) and the luminal A subtype ( p = 0.003). On univariate analysis shorter overall survival was associated with stromal diamine oxidase negativity ( p = 0.008), especially in lung metastases ( p = 0.025), and stromal monoamine oxidase B positivity ( p < 0.001). Stromal monoamine oxidase B positivity was an independent prognostic factor for shorter overall survival in multivariate Cox analysis (hazard ratio, 4.069; 95% confidence interval, 1.649–10.04; p = 0.002). Finally, in metastatic breast cancer, amine oxidase-related proteins were differentially expressed in a manner specific to metastatic site, and stromal monoamine oxidase B expression was correlated with prognosis.

Breast Cancer Metastatic to the Choroid in a Male Patient Case Report

Choroidal metastases have been observed in about 8% of patients with metastatic breast cancer, even if their true incidence is likely to be higher, as they are not routinely investigated in the absence of symptoms. Radiotherapy is the treatment of choice for symptom palliation. The prognosis is traditionally poor, with a reported average survival of one year. Here we describe the third case reported in the literature of a metastatic tumor to the choroid from a male breast carcinoma.

Metastatic Breast Cancer Shows Different Immunohistochemical Phenotype According to Metastatic Site

Aims and background

The study was performed to assess the status of immunohistochemical markers in primary and metastatic breast cancer and to determine the organ-specific characteristics of metastatic breast cancer.

Methods

Samples from 13 cases of paired primary and metastatic breast cancer and 34 cases of metastatic breast cancer were included.

Results

In the analysis of 13 cases of paired primary and metastatic breast cancer, estrogen receptor and progesterone receptor loss were noted in 1 (7.7%) case each. Androgen receptor loss and gain was noted in 2 (15.4%) cases, respectively. HER-2 showed 100% concordance with primary and metastatic tumors. C-kit was demonstrated in only 2 (15.4%) cases of metastatic breast cancer. In the analysis of 34 cases of metastatic breast cancer, when classified into triple-negative type (ER-, PR-, and HER-2-), HER-2+ type, and ER+ or PR+/HER-2- type according to immunohistochemical stain results, HER-2 type (66.7%) in brain metastasis and ER+ or PR+/HER-2- type (75.0%) in liver metastasis were predominant. Bone metastasis was composed of triple negative type (44.4%) and ER+ or PR+/HER-2- type (55.6%), and lung metastasis showed all of three subtypes in similar proportions.

Conclusions

Metastatic breast cancer shows different immunohistochemical phenotypes according to metastatic site (P = 0.048).

Toosendanin demonstrates promising antitumor efficacy in osteosarcoma by targeting STAT3

Signal transducer and activator of transcription 3(STAT3) is an emerging target for cancer therapy. In this study, we identify Toosendanin (TSN) is an effective inhibitor of STAT3, leading to the impediment of various oncogenic processes in osteosarcoma. TSN selectively inactivates phospho-STAT3 (Tyr-705); subsequent molecular docking and in vitro SPR analysis uncover TSN directly binds to the SH2 domain of STAT3. Consequently, TSN blocks STAT3 dimerization and impairs the complex formation of STAT3 and epidermal growth factor receptor (EGFR). In an animal tumor model study, TSN is well tolerated, inhibits osteosarcoma growth and metastasis. In another osteosarcoma patient-derived xenografts (PDX) model, we find TSN triggers strong inhibitory effects on patient-derived tumors. Further studies show that TSN also displays activity against other solid tumors. Our preclinical work therefore supports that TSN acts as a novel inhibitor of STAT3 that blocks tumorigenesis in ostoesarcoma.

Differential Site-Based Expression of Pentose Phosphate Pathway-Related Proteins among Breast Cancer Metastases

Purpose. We aimed to investigate the expression of pentose phosphate pathway- (PPP-) related proteins in metastatic breast cancer and its relationship with clinicopathologic factors. Methods. Tissue samples from 126 metastatic breast cancers were included in a tissue microarray. Expression of PPP-related proteins [glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconolactonase (6PGL), 6-phosphogluconate dehydrogenase (6PGDH), and nuclear factor erythroid 2-related factor (NRF2)] was determined by immunohistochemistry. Results. G6PDH (p = 0.011) and cytoplasmic NRF2 (p = 0.001) showed the highest expression in brain metastases. Human epidermal growth factor receptor (HER-2) positivity was associated with G6PDH (p < 0.001) and cytoplasmic NRF2 (p = 0.015) positivity. A high Ki-67 labeling index (LI) was correlated with nuclear NRF2 positivity (p = 0.037), and HER-2-positive luminal B type was associated with G6PDH positivity (p = 0.001). On multivariate Cox analysis, independent risk factors of short overall survival were 6PGL positivity in bone metastasis (HR 4.180, 95% CI 1.160–15.06, p = 0.029) and low Ki-67 LI in lung metastasis (HR 11.853, 95% CI 1.841–76.30, p = 0.009). Conclusion. Differential expression of PPP-related proteins correlated with different prognoses and metastatic sites, with the highest expression in brain metastases, and could be a potential therapeutic target.

Cancer and the metastatic substrate

Seventy percent of cancer patients have detectable metastases when they receive a diagnosis and 90% of cancer deaths result from metastases. These two facts emphasise the urgency for research to study the mechanisms and processes that enable metastasis. We need to develop a greater understanding of the cellular and molecular mechanisms that cause metastasis and also we need to do more. We must also consider the micro- and macro-environmental factors that influence this disease. Studying this environmental context has led us to update the ‘seed and soil’ hypothesis which dates back to the 19th century. This theory describes cancerous cells as seeds and the substrate as the soil in target organs though this may seem antiquated. Nonetheless, the tissue specificity that researchers have recently observed in metastatic colonisation supports the validity of the seed and soil theory. We now know that the metastatic potential of a tumour cell depends on multiple, reciprocal interactions between the primary tumour and distant sites. These interactions determine tumour progression. Studies of metastasis have allowed us to develop treatments that focus on therapeutic effectiveness. These new treatments account for the frequent metastasis of some tumours to target organs such as bones, lungs, brain, and liver. The purpose of this review is first to describe interactions between the cellular and molecular entities and the target organ tumour environment that enables metastasis. A second aim is to describe the complex mechanisms that mediate these interactions.

BROWNIAN DYNAMICS SIMULATION OF CATCH TO SLIP TRANSITION OVER A MODEL ENERGY LANDSCAPE

We perform Brownian dynamics simulation (BDS) of catch to slip transition over a model energy landscape. Through our BDS we demonstrate that for forces below the critical force the bond rupture occurs mostly through the catch pathway while for forces above the critical force the bond rupture occurs mostly through the slip pathway. We also demonstrate that the shoulder in the bond rupture force distribution switches to peak as the loading rate increases progressively and the bond lifetime is maximized at the model dependent critical force. The force dependent bond lifetime obtained via transforming the bond rupture force distribution at a given loading rate is in excellent agreement with that obtained from our BDS at constant forces. An alternative to the current mechanism of catch to slip transition is presented and validated through BDS.

Versatile roles of extracellular vesicles in cancer

Numerous studies have shown that non-cell-autonomous regulation of cancer cells is an important aspect of tumorigenesis. Cancer cells need to communicate with stromal cells by humoral factors such as VEGF, FGFs, and Wnt in order to survive. Recently, extracellular vesicles (EVs) have also been shown to be involved in cell-cell communication between cancer cells and the surrounding microenvironment and to be important for the development of cancer. In addition, these EVs contain small noncoding RNAs, including microRNAs (miRNAs), which contribute to the malignancy of cancer cells. Here, we provide an overview of current research on EVs, especially miRNAs in EVs. We also propose strategies to treat cancers by targeting EVs around cancer cells.

Decoding the Secret of Cancer by Means of Extracellular Vesicles

One of the recent outstanding developments in cancer biology is the emergence of extracellular vesicles (EVs). EVs, which are small membrane vesicles that contain proteins, mRNAs, long non-coding RNAs, and microRNAs (miRNAs), are secreted by a variety of cells and have been revealed to play an important role in intercellular communications. These molecules function in the recipient cells; this has brought new insight into cell-cell communication. Recent reports have shown that EVs contribute to cancer cell development, including tumor initiation, angiogenesis, immune surveillance, drug resistance, invasion, metastasis, maintenance of cancer stem cells, and EMT phenotype. In this review, I will summarize recent studies on EV-mediated miRNA transfer in cancer biology. Furthermore, I will also highlight the possibility of novel diagnostics and therapy using miRNAs in EVs against cancer.

Expression of cancer-associated fibroblast related proteins in metastatic breast cancer: an immunohistochemical analysis

Background

Cancer-associated fibroblast (CAF) is the most studied element of the tumor microenvironment, although no relationship has been identified between expression of their related proteins and the metastasis site. The purpose of this study was to investigate the expression of CAF related proteins and their implications according to the metastasis site in metastatic breast cancer.

Methods

Immunohistochemical staining was used to evaluate the expression of CAF related proteins (podoplanin, prolyl 4-hydroxylase, FAPα, S100A4, PDGFRα, PDGFRβ, and NG2) in tissue microarrays from 132 cases of metastatic breast cancer (bone metastasis: 32 cases, brain metastasis: 38 cases, liver metastasis: 10 cases, and lung metastasis: 52 cases). Breast cancer subtypes were classified as luminal A, luminal B, HER-2, and triple negative breast cancer, according to the immunohistochemical staining results for estrogen and progesterone receptors, HER-2, and Ki-67 and FISH results for HER-2. Tumors were classified as desmoplastic, sclerotic, normal-like, and inflammatory type, according to the histologic findings from the tumor stroma.

Results

Various CAF related protein expression profiles were observed, according to the metastasis site. For bone metastasis, the expression of stromal podoplanin, S100A4, and PDGFRα was significantly high. For lung metastasis, the expression of stromal PDGFRβ was significantly elevated (p < 0.001). For liver metastasis, significantly reduced expression of stromal S100A4 (p = 0.002) and PDGFRα (p = 0.011) was observed. Expression of CAF related proteins also differed according to the stromal phenotype. Desmoplastic stroma exhibited significantly elevated expression of stromal podoplanin (p < 0.001), S100A4 (p < 0.001), PDGFRα (p = 0.010), and PDGFRβ (p = 0.021). Inflammatory stroma exhibited significantly elevated expression of stromal FAPα (p = 0.044) and significantly reduced stromal S100A4 expression (p < 0.001). Sclerotic stroma exhibited significantly elevated tumoral FAPα (p = 0.005) expression. For lung metastasis, shorter overall survival was significantly related to tumoral podoplanin expression (p = 0.006), stromal podoplanin expression (p = 0.018), tumoral prolyl 4-hydroxylase negativity (p = 0.016), and tumoral PDGFRα expression (p = 0.001).

Conclusion

For metastatic breast cancer, significant differences were observed in the expression of CAF related proteins, according to the metastasis site and stromal histologic phenotype.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0587-9) contains supplementary material, which is available to authorized users.

Effects of cellular viscoelasticity in lifetime extraction of single receptor-ligand bonds

Single-molecule force spectroscopy is widely used to determine kinetic parameters of dissociation by analyzing bond rupture data obtained via applying mechanical force to cells, capsules, and beads that are attached to an intermolecular bond. The bond rupture data are obtained in experiments either at a constant force or at a constant loading rate. We explore the effect of cellular viscoelasticity in constant-force experiments. Specifically, we perform Monte Carlo simulations of bond rupture at a given constant force to obtain the bond lifetime as a function of force in the absence and in the presence of bond force modulation due to cellular viscoelasticity, to explore its effect on the bond lifetime.

Brain metastatic cancer cells release microRNA-181c-containing extracellular vesicles capable of destructing blood-brain barrier

Brain metastasis is an important cause of mortality in breast cancer patients. A key event during brain metastasis is the migration of cancer cells through blood–brain barrier (BBB). However, the molecular mechanism behind the passage through this natural barrier remains unclear. Here we show that cancer-derived extracellular vesicles (EVs), mediators of cell–cell communication via delivery of proteins and microRNAs (miRNAs), trigger the breakdown of BBB. Importantly, miR-181c promotes the destruction of BBB through the abnormal localization of actin via the downregulation of its target gene, PDPK1. PDPK1 degradation by miR-181c leads to the downregulation of phosphorylated cofilin and the resultant activated cofilin-induced modulation of actin dynamics. Furthermore, we demonstrate that systemic injection of brain metastatic cancer cell-derived EVs promoted brain metastasis of breast cancer cell lines and are preferentially incorporated into the brain in vivo. Taken together, these results indicate a novel mechanism of brain metastasis mediated by EVs that triggers the destruction of BBB.

A key event during metastasis to the brain is the migration of cancer cells through the blood–brain barrier (BBB). Here the authors show that cancer-cell-derived extracellular vesicles promote metastasis by promoting BBB breaching.

Anti-metastatic effects of the sulfated polysaccharide ascophyllan isolated from Ascophyllum nodosum on B16 melanoma

We previously found that ascophyllan, a sulfated polysaccharide isolated from brown seaweed Ascophyllum nodosum, exhibited antitumor activity in sarcoma-180 tumor-bearing mice. In this study, we found that ascophyllan inhibited the migration and adhesion of B16 melanoma cells by reducing the expression of N-cadherin and enhancing the expression of E-cadherin in a concentration-dependent manner. Transwell invasion assay revealed that ascophyllan suppressed the invasion ability of B16 cells. It also inhibited the expression of matrix metalloprotease-9 (MMP-9) mRNA and the secretion of MMP-9 protein in B16 cells, a process that may involve the extracellular signal-regulated kinase (ERK) signaling pathway. Furthermore, ascophyllan administered intraperitoneally at 25 mg/kg showed anti-metastatic activity in a mouse model of metastasis induced by intravenous injection of B16 cells, and the number of lung surface metastatic nodules in ascophyllan-treated mice was significantly reduced compared to that in the untreated control mice. Since splenic natural killer cell activity enhanced in the mice injected with ascophyllan intraperitoneally, we suggest that ascophyllan may exhibit in vivo anti-metastatic activity on B16 melanoma cells through activation of the host immune system in addition to a direct action on cancer cells.

Site-specific metabolic phenotypes in metastatic breast cancer

Background

The purpose of this study was to examine the expression of metabolism-related proteins according to metastatic site in metastatic breast cancer and to assess the implication of site-specific differential expression.

Methods

A tissue microarray containing 162 cases of metastatic breast cancer (52 lung metastasis, 47 bone metastasis, 39 brain metastasis, and 24 liver metastasis) was constructed. It was subject to immunohistochemical staining of the following proteins: Glycolysis-related: Glut-1, hexolinase II, carbonic anhydrase (CA) IX, and monocarboxylate transporter (MCT) 4; glutaminolysis-related: glutaminase (GLS) 1, glutamate dehydrogenase (GDH), and amino acid transporter (ASCT) 2; mitochondrial metabolism-related: ATP synthase, succinate dehydrogenase (SDH)A, and SDHB; and serine/glycine metabolism related: phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase (PSAT), phosphoserine phosphatase (PSPH), glycine decarboxylase (GLDC), and serine hydroxymethyltransferase (SHMT).

Results

The expression levels of glycolysis-related-proteins (Glut-1, hexokinase II, CAIX, and MCT4) differed according to metastatic site, with higher expression seen in the brain and lower expression in the bone and liver (p < 0.001, 0.001, 0.009, and <0.001, respectively). Differences in metabolic phenotype were analyzed according to metastasis site. Glycolysis type was most frequently encountered in the brain and lung (p < 0.001). In univariate analysis, the factors associated with shorter overall survival were CAIX positivity (p = 0.044), PSPH positivity (p = 0.045), and SHMT1 positivity (p = 0.002), as well as serine/glycine type (p = 0.041).

Conclusions

Differences in metabolic features according to metastatic site were seen in metastatic breast cancer, with the glycolysis phenotype found predominantly in the brain and lung and the non-glycolysis phenotype in the bone and liver.

Expression of MTA1 in nasopharyngeal carcinoma and its correlation with prognosis

Metastasis-associated protein 1 (MTA1) is related to tumour metastasis and poor prognosis in various human cancers. The aim of this study was to investigate the expression of MTA1 in nasopharyngeal carcinoma (NPC) and explore the prognostic value of MTA1 in NPC patients. The expression of MTA1 in 136 human NPC tissues and 20 normal nasopharyngeal tissues was detected using immunohistochemistry, quantified and classified into low or high expression using a 50% cut-off level. The relationships of MTA1 expression with the clinical characteristics and survival of patients were analysed. MTA1-positive staining was observed in the nuclei of NPC cells, and MTA1 expression was significantly correlated with T stage (P = 0.006), clinical stage (P = 0.001) and distant metastasis (P < 0.001). Patients with high MTA1 expression exhibited significantly worse distant metastasis-free survival (DMFS) than those with low MTA1 expression (90.75% vs. 70.81%, P = 0.017). Multivariate survival analysis revealed that MTA1 expression was an independent prognostic factor for DMFS (P = 0.038). In this study, high MTA1 expression was significantly associated with poor DMFS in NPC, indicating that MTA1 could serve as a novel biomarker for assessing the metastatic potential of NPC and could act as a possible therapeutic target for the treatment of metastatic nasopharyngeal carcinoma.

Effects of cellular viscoelasticity in multiple-bond force spectroscopy

Receptor-ligand bonds are often subjected to forces that regulate their detachment via modulating off-rates. Though the dynamics of detachment is primarily controlled by the physical chemistry of adhesion molecules cellular features such as cell deformability and microvillus viscoelasticity have been shown to have an effect on it as well. In this work, Monte Carlo simulation of the rupture of multiple receptor-ligand bonds between substrate and a polymorphonuclear leukocyte (PMN) cell suspended in a Newtonian fluid is performed. It is demonstrated via various micromechanical models of the PMN cell adhered to the substrate by multiple receptor-ligand bonds that viscous drag caused by relative motion of cell suspended in a Newtonian fluid and cellular viscoelasticity modulate transmission of an applied external load to receptor-ligand bonds. It is demonstrated that due to cellular viscoelasticity the instantaneous intermolecular bond force is lower than the instantaneous applied force. It is also demonstrated that due to cellular viscoelasticity, the mean intermolecular bond rupture forces are lowered while the mean bond lifetime increases.

Stress as a fundamental theme in cell plasticity

Over a decade of intensive investigation of the possible plasticity of mammalian cells has eventually substantiated that mammalian species are endowed with a remarkable capacity to change mature cell fates. We review below the evidence for the occurrence of processes such as dedifferentiation and transdifferentiation within mammalian tissues in vivo, and in cells removed from their protective microenvironment and seeded in culture under conditions poorly resembling their physiological state in situ. Overall, these studies point to one major conclusion: stressful conditions, whether due to in vivo tissue damage or otherwise to isolation of cells from their in vivo restrictive niches, lead to extreme fate changes. Some examples of dedifferentiation are discussed in detail showing that rare cells within the population tend to turn back into less mature ones due to severe cell damage. It is proposed that cell stress, mechanistically sensed by isolation from neighboring cells, leads to dedifferentiation, in an attempt to build a new stem cell reservoir for subsequent regeneration of the damaged tissue. This article is part of a Special Issue entitled: Stress as a fundamental theme in cell plasticity.

Galectin-3 expressed on different lung compartments promotes organ specific metastasis by facilitating arrest, extravasation and organ colonization via high affinity ligands on melanoma cells

Interactions between molecules on the surface of tumor cells and those on the target organ endothelium play an important role in their arrest in an organ. Galectin-3 on the lung endothelium and high affinity ligands poly-N-acetyllactosamine (polyLacNAc) on N-oligosaccharides on melanoma cells facilitate such interactions. However, to extravasate and colonize an organ the cells must stabilize these interactions by spreading to retract endothelium, degrade exposed basement membrane (BM) and move into parenchyma and proliferate. Here, we show that galectin-3 is expressed on all the major compartments of the lungs and participates in not just promoting adhesion but also in spreading. We for the first time demonstrate that both soluble and immobilized galectin-3 induce secretion of MMP-9 required to breach vascular BM. Further, we show that immobilized galectin-3 is used as traction for the movement of cells. Downregulation of galactosyltransferases-I and -V resulted in significant loss in expression of polyLacNAc and thus reduced binding of galectin-3. This was accompanied with a loss in adhesion, spreading, MMP-9 secretion and motility of the cells on galectin-3 and thus their metastasis to lungs. Metastasis could also be inhibited by blocking surface polyLacNAc by pre-incubating cells with truncated galectin-3 (which lacked oligomerization domain) or by feeding mice with modified citrus pectin in drinking water. Overall, these results unequivocally show that polyLacNAc on melanoma cells and galectin-3 on the lungs play a critical role in arrest and extravasation of cells in the lungs and strategies that target these interactions inhibit lung metastasis.

Metastasis-associated protein 1 as a new prognostic marker for solid tumors: a meta-analysis of cohort studies

Metastasis-associated protein 1 (MTA1) is a molecular marker in various solid tumors that has recently been investigated. The prognostic significance of MAT1 expression remains controversial. In this work, we aimed to determine the relationship between immunohistochemistry-detected MAT1 expression and survival of patients with solid tumors by conducting a meta-analysis of cohort studies. Relevant studies were identified via an electronic database search updated on October 28, 2013. We included cohort studies that reported hazard ratios (HRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) to determine the association of high MTA1 expression with overall survival (OS) and clinicopathological characteristics. Heterogeneity was quantified using I (2) statistics, and publication bias was evaluated using funnel plots. Sensitivity analysis was conducted to evaluate the robustness of meta-analysis findings. We identified 16 cohort studies that focused on MTA1 overexpression and prognosis involving 2,253 cancer patients. Overall, the combined HR for OS was 1.85 (95 % CI: 1.55-2.28, P<0.001). Omission of any single study had no significant effect on the pooled HR estimate. When the studies were stratified by tumor type, similar results of poor prognosis were observed in non-small cell lung cancer (HR=2.05, 95 % CI: 1.14-3.68, P=0.016) and esophageal squamous cell carcinoma (HR=1.86, 95 % CI: 1.44-2.39, P<0.001). Moreover, multivariate survival analysis showed that MTA1 overexpression was an independent predictor of poor prognosis (HR=1.90, 95 % CI: 1.53-2.37, P<0.001). In addtional, MTA1 overexpression was significantly associated with tumor size (OR=2.72, 95 % CI=1.44-5.14, P=0.002), tumor stage (OR=2.44, 95 % CI=1.67-3.57, P<0.001), depth of invasion (OR=2.63, 95 % CI=1.74-3.97, P<0.001), and lymph node metastasis (OR=2.57, 95 % CI=1.57-4.19, P<0.001). However, when age, sex, and tumor differentiation were considered, no obvious association was observed. This study provides a comprehensive examination of the literature available on the association of MTA1 overexpression with OS and some clinicopathological features in solid tumors. Meta-analysis results provide evidence that MTA1 may be a new indicator of poor cancer prognosis. Considering the limitations of the eligible studies, other large-scale prospective trials must be conducted to clarify the prognostic value of MTA1 in predicting cancer survival.

Prostate cancer and bone: the elective affinities

The onset of metastases dramatically changes the prognosis of prostate cancer patients, determining increased morbidity and a drastic fall in survival expectancy. Bone is a common site of metastases in few types of cancer, and it represents the most frequent metastatic site in prostate cancer. Of note, the prevalence of tumor relapse to the bone appears to be increasing over the years, likely due to a longer overall survival of prostate cancer patients. Bone tropism represents an intriguing challenge for researchers also because the preference of prostate cancer cells for the bone is the result of a sequential series of targetable molecular events. Many factors have been associated with the peculiar ability of prostate cancer cells to migrate in bone marrow and to determine mixed osteoblastic/osteolytic lesions. As anticipated by the success of current targeted therapy aimed to block bone resorption, a better understanding of molecular affinity between prostate cancer and bone microenvironment will permit us to cure bone metastasis and to improve prognosis of prostate cancer patients.

Stimuli-induced organ-specific injury enhancement of organotropic metastasis in a spatiotemporal regulation

The relationship between inflammation and tumorigenesis has been established. Recently, inflammation is also reported to be a drive force for cancer metastasis. Further evidences show that various stimuli directly induced-injury in a specific organ can also promote metastasis in this organ, which include epidemiological reports, clinical series and experimental studies. Each type of cancer has preferential sites for metastasis, which is also due to inflammatory factors that are released by primary cancer to act on these sites and indirectly induce injuries on them. Host factors such as stress,fever can also influence distant metastasis in a specific site through stimulation of immune and inflammatory effects. The five aspects support an idea that specific-organ injury directly induced by various stimuli or indirectly induced by primary tumor or host factors activation of proinflammatory modulators can promote metastasis in this organ through a spatiotemporal regulation, which has important implications for personalized prediction, prevention and management of cancer metastasis.

Rupture of multiple catch-slip bonds: Two-state two-pathway catch-slip bonds

We performed Monte Carlo simulation of the detachment of a polymorphonuclear (PMN) leukocyte immersed in a Newtonian fluid and adhered to a substrate by multiple catch-slip bonds. We found that at certain loading rates the interplay of multiple catch-slip bonds leads to a bimodal distribution of the bond rupture force. We also found that the low force peak in these bond rupture force distributions switches to a high force peak with a gradual increase in the loading rate. These trends in the bond rupture force distributions are characteristics of two-state systems. Consequently, though individual catch-slip bonds follow one-state two-pathway energy landscape, their interplay mimics a two-state two-pathway energy landscape.

Milky spots promote ovarian cancer metastatic colonization of peritoneal adipose in experimental models

The goal of controlling ovarian cancer metastasis formation has elicited considerable interest in identifying the tissue microenvironments involved in cancer cell colonization of the omentum. Omental adipose is a site of prodigious metastasis in both ovarian cancer models and clinical disease. This tissue is unusual for its milky spots, comprised of immune cells, stromal cells, and structural elements surrounding glomerulus-like capillary beds. The present study shows the novel finding that milky spots and adipocytes play distinct and complementary roles in omental metastatic colonization. In vivo assays showed that ID8, CaOV3, HeyA8, and SKOV3ip.1 cancer cells preferentially lodge and grow within omental and splenoportal fat, which contain milky spots, rather than in peritoneal fat depots. Similarly, medium conditioned by milky spot-containing adipose tissue caused 75% more cell migration than did medium conditioned by milky spot-deficient adipose. Studies with immunodeficient mice showed that the mouse genetic background does not alter omental milky spot number and size, nor does it affect ovarian cancer colonization. Finally, consistent with the role of lipids as an energy source for cancer cell growth, in vivo time-course studies revealed an inverse relationship between metastatic burden and omental adipocyte content. Our findings support a two-step model in which both milky spots and adipose have specific roles in colonization of the omentum by ovarian cancer cells.

Inhibiting interleukin-19 activity ameliorates esophageal squamous cell carcinoma progression

Background

IL-19 is expressed in esophageal squamous cell carcinoma (SCC), but its biological effect on esophageal cancer remains unclear. We determined the correlation between IL-19 expression levels and clinicopathological variables and explored the effects of IL-19 on the esophageal SCC in vivo and in vitro.

Methodology/Principal Findings

We determined the expression levels of esophageal SCC tissues from 60 patients using immunohistochemistry. We examined the effects of IL-19 on intracellular signaling, cytokines production as well as proliferation, colonization, and migration in the human esophageal SCC cell line CE81T. Monoclonal antibodies (mAbs) against IL-19 (1BB1) and its receptor IL-20R1 (51D) were used to antagonize the effects of IL-19. We injected SCID mice with CE81T cells and then treated them with anti-IL-19 mAb or control IgG every 3 days and determined tumor growth for 32 days. Of the 60 esophageal SCC patients, 36 patients (60%) were IL-19 strongly stained, which was associated with advanced tumor stage. CE81T cells expressed IL-19 and its receptors. IL-19 induced phosphorylation of STAT3, P38, JNK, ERK1/2, Akt, and NF-κB in CE81T cells. IL-19 promoted the proliferation, colonization, and migration of CE81T cells, which were antagonized by 1BB1 and 51D. IL-19 also induced expression of the transcripts of TGF-β, cyclin B1, CXCR4, and MMP-1 in CE81T cells. In CE81T tumor-bearing mice, 1BB1 reduced tumor growth and downregulated TGF-β, cyclin B1, MMP-1, and CXCR4 expression in tumors.

Conclusions/Significance

IL-19 affects the pathogenesis of esophageal cancer. IL-19 mAb (1BB1) is potentially a potent drug for esophageal cancer therapy.

Flavonoids from Citrus unshiu Marc. inhibit cancer cell adhesion to endothelial cells by selective inhibition of VCAM-1

Citrus fruits have been used as edible fruit and a component of traditional medicine for various diseases including cancer since ancient times. Herein, we investigated the anticancer activity of flavonoids of Citrus unshiu Marc. (FCM) focusing on anti-metastatic effects. We prepared FCM and performed experiments using MDA-MB-231 human breast cancer cells. FCM inhibited TNF-induced cancer cell adhesion to human umbilical vein endothelial cells (HUVECs) without showing any toxicity. FCM inhibited the expression of VCAM-1, but not of ICAM-1, on MDA-MB-231 cells as well as HUVECs. FCM inhibited protein kinase C (PKC) phosphorylation, but not Akt phosphorylation. FCM also inhibited cancer cell invasion in a dose-dependent manner, but not MMP-9 expression. In conclusion, this study suggested that FCM inhibits TNF-induced cancer cell adhesion to HUVECs by inhibiting VCAM-1 through inhibition of PKC, providing evidence that FCM have anti-metastatic activity by inhibiting adhesion molecules and invasion on human breast cancer cells.

Clonal expansion analysis of transposon insertions by high-throughput sequencing identifies candidate cancer genes in a PiggyBac mutagenesis screen

Somatic transposon mutagenesis in mice is an efficient strategy to investigate the genetic mechanisms of tumorigenesis. The identification of tumor driving transposon insertions traditionally requires the generation of large tumor cohorts to obtain information about common insertion sites. Tumor driving insertions are also characterized by their clonal expansion in tumor tissue, a phenomenon that is facilitated by the slow and evolving transformation process of transposon mutagenesis. We describe here an improved approach for the detection of tumor driving insertions that assesses the clonal expansion of insertions by quantifying the relative proportion of sequence reads obtained in individual tumors. To this end, we have developed a protocol for insertion site sequencing that utilizes acoustic shearing of tumor DNA and Illumina sequencing. We analyzed various solid tumors generated by PiggyBac mutagenesis and for each tumor >10⁶ reads corresponding to >10⁴ insertion sites were obtained. In each tumor, 9 to 25 insertions stood out by their enriched sequence read frequencies when compared to frequencies obtained from tail DNA controls. These enriched insertions are potential clonally expanded tumor driving insertions, and thus identify candidate cancer genes. The candidate cancer genes of our study comprised many established cancer genes, but also novel candidate genes such as Mastermind-like1 (Mamld1) and Diacylglycerolkinase delta (Dgkd). We show that clonal expansion analysis by high-throughput sequencing is a robust approach for the identification of candidate cancer genes in insertional mutagenesis screens on the level of individual tumors.

Rupture of single receptor-ligand bonds: a new insight into probability distribution function

Single molecule force spectroscopy is widely used to determine kinetic parameters of dissociation by analyzing bond rupture data obtained via applying mechanical force to cells, capsules, and beads that are attached to an intermolecular bond. The current analysis assumes that the intermolecular bond force is equal to the externally applied mechanical force. We confirm that viscous drag alone or in combination with cellular deformation resulting in viscoelasticity modulates bond force so that the instantaneous intermolecular bond force is not equivalent to the applied force. The bond force modulation leads to bond rupture time and force histograms that differ from those predicted by probability distribution function (PDF) using the current approach. A new methodology that accounts for bond force modulation in obtaining PDF is presented. The predicted histograms from the new methodology are in excellent agreement with the respective histograms obtained from Monte Carlo simulation.

Effect of viscous drag on multiple receptor-ligand bonds rupture force

Monte Carlo simulation of the rupture of multiple receptor-ligand bonds between two PMN cells suspended in a Newtonian fluid is performed. We demonstrate via micro-mechanical model of two cells adhered by multiple receptor-ligand bonds that viscous drag caused by relative motion of cell suspended in a Newtonian fluid modulates transmission of an applied external load to bonds. Specifically, it is demonstrated that at any time the intermolecular bond force is not equivalent to the instantaneous applied force. The difference in the instantaneous applied force and the intermolecular bond force depends on the viscosity of fluid, the size of cell, the applied loading rate, and the number of bonds at any instant of time. Viscous drag acting on cell reduces average bond rupture forces.

Biology of brain metastases and novel targeted therapies: time to translate the research

Brain metastases (BM) occur in 20% to 40% of patients with cancer and result in significant morbidity and poor survival. The main therapeutic options include surgery, whole brain radiotherapy, stereotactic radiosurgery and chemotherapy. Although significant progress has been made in diagnostic and therapeutic methods, the prognosis in these patients remains poor. Furthermore, the poor penetrability of chemotherapy agents through the blood brain barrier (BBB) continues to pose a challenge in the management of this disease. Preclinical evidence suggests that new targeted treatments can improve local tumor control but our clinical experience with these agents remains limited. In addition, several clinical studies with these novel agents have produced disappointing results. This review will examine the knowledge of targeted therapies in BM. The preclinical and clinical evidence of their use in BM induced by breast cancer, non-small cell lung cancer and melanoma will be presented. In addition, we will discuss the role of antiangiogenic and radiosensitising agents in the treatment of BM and the current strategies available to increase BBB permeability. A better understanding of the mechanism of action of these agents will help us to identify the best targets for testing in future clinical studies.

Computerized analysis of tumor cell interactions with extracellular matrix proteins, peptides, and endothelial cells under laminar flow

Arrest and formation of stable adhesive interactions between circulating cells and the endothelium or exposed subendothelial matrix are important processes in many biological situations. We have developed a highly sensitive hydrodynamic assay that utilizes a parallel-plate flow chamber, video microscopy, and digital image processing to separate and measure the primary arrest and adhesion stabilization of flowing cells. Our data indicate that primary cell contact triggers secondary adhesion stabilization, and the secondary events are likely to be critical to metastasis formation. To study the relationship between tumor cell adhesion stabilization and organ-specific blood-borne metastasis, we investigated the adhesion stabilization of metastatic murine RAW117 large-cell lymphoma cells to the extracellular matrix proteins fibronectin and vitronectin, several Arg-Gly-Asp (RGD) containing peptides, and microvascular endothelial cells from the liver or lung. The highly liver metastatic RAW117-H10 subline showed the fastest stabilization to fibronectin, vitronectin, and RGD peptides. Poorly metastatic RAW117-P cells had stabilization times 3-10 times longer than for RAW117-H10 cells, while the lung- and liver-metastatic RAW117-L17 subline failed to stabilize at all. The adhesion stabilization of the RAW117-H10 cells to the extracellular matrix proteins and RGD peptides was inhibited by anti-beta(3) integrin monoclonal antibodies and RGD peptides. In contrast, the RAW117-L17 subline had the shortest stabilization time to unstimulated microvascular endothelial cells of the lung and hepatic sinusoids, followed by RAW117-H10 cells and RAW117-P cells. Monoclonal antibodies against the beta(3) integrin subunit and RGD peptides did not inhibit adhesion stabilization of RAW117-H10 cells to endothelial cells, suggesting that different metastatic variants of large-cell lymphoma cells use differing mechanisms to adhere to organ-specific endothelial cells.

The role of microenvironment in tumor angiogenesis

Tumor microenvironment is essential for tumor cell proliferation, angiogenesis, invasion and metastasis through its provision of survival signals, secretion of growth and pro-angiogenic factors, and direct adhesion molecule interactions. This review examines its importance in the induction of an angiogenic response in tumors and in multiple myeloma. The encouraging results of pre-clinical and clinical trials in which tumors have been treated by targeting the tumor microenvironment are also discussed.