Brain metastasis-initiating cells: survival of the fittest

De novo GTP synthesis is a metabolic vulnerability for the interception of brain metastases

Patients with brain metastases (BM) face a 90% mortality rate within one year of diagnosis and the current standard of care is palliative. Targeting BM-initiating cells (BMICs) is a feasible strategy to treat BM, but druggable targets are limited. Here, we apply Connectivity Map analysis to lung-, breast-, and melanoma-pre-metastatic BMIC gene expression signatures and identify inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in the de novo GTP synthesis pathway, as a target for BM. We show that pharmacological and genetic perturbation of IMPDH attenuates BMIC proliferation in vitro and the formation of BM in vivo. Metabolomic analyses and CRISPR knockout studies confirm that de novo GTP synthesis is a potent metabolic vulnerability in BM. Overall, our work employs a phenotype-guided therapeutic strategy to uncover IMPDH as a relevant target for attenuating BM outgrowth, which may provide an alternative treatment strategy for patients who are otherwise limited to palliation.

A Nomogram Based on Clinicopathological Characteristics for Estimating the Risk of Brain Metastasis from Advanced Gastric Cancer: A Multi-Center Retrospective Clinical Study

Purpose

Although brain metastasis (BM) from gastric cancer (GC) is relatively uncommon, its incidence has been increasing owing to advancements in treatment modalities. Unfortunately, patients diagnosed with BM from gastric cancer have poor life expectancy. Our study aims to establish a predictive model for brain metastasis in advanced gastric cancer patients, thus enabling the timely diagnosis of brain metastasis.

Patients and Methods

The clinicopathological features of a cohort which included 40 GC patients with brain metastasis, 32 of whom from the First Affiliated Hospital of Nanchang University, 2 from Gaoxin Branch of the First Affiliated Hospital of Nanchang University, remaining 6 from Anyang District Hospital, and 80 non-metastatic advanced GC patients from the First Affiliated Hospital of Nanchang University between 2018 and 2022. Data were retrospectively analyzed.

Results

Age, tumor size, differentiation, lymph node grade, tumor location, Lauren classification, liver metastasis, carbohydrate antigen 199 (CA199), lactate dehydrogenase (LDH), and human epidermal growth factor receptor 2 (Her-2) were associated with BM. A nomogram integrated with nine risk factors (tumor size, differentiation, lymph node grade, tumor location, Lauren classification, liver metastasis, CA-199, LDH, and Her-2) showed good performance (Area Under Curve 0.95, 95% CI: 0.91-0.98).

Conclusion

We developed and validated a nomogram that achieved individualized prediction of the possibility of BM from GC. This model enables personalized imaging review schedules for timely brain metastasis detection in advanced gastric cancer patients.

SRRM4-mediated REST to REST4 dysregulation promotes tumor growth and neural adaptation in breast cancer leading to brain metastasis

BACKGROUND

Effective control of brain metastasis remains an urgent clinical need due a limited understanding of the mechanisms driving it. Although the gain of neuro-adaptive attributes in breast-to-brain metastases (BBMs) has been described, the mechanisms that govern this neural acclimation and the resulting brain metastasis competency are poorly understood. Herein, we define the role of neural-specific splicing factor Serine/Arginine Repetitive Matrix Protein 4 (SRRM4) in regulating microenvironmental adaptation and brain metastasis colonization in breast cancer cells.

METHODS

Utilizing pure neuronal cultures and brain-naive and patient-derived BM tumor cells, along with in vivo tumor modeling, we surveyed the early induction of mediators of neural acclimation in tumor cells.

RESULTS

When SRRM4 is overexpressed in systemic breast cancer cells, there is enhanced BBM leading to poorer overall survival in vivo. Concomitantly, SRRM4 knockdown expression does not provide any advantage in central nervous system metastasis. In addition, reducing SRRM4 expression in breast cancer cells slows down proliferation and increases resistance to chemotherapy. Conversely, when SRRM4/REST4 levels are elevated, tumor cell growth is maintained even in nutrient-deprived conditions. In neuronal coculture, decreasing SRRM4 expression in breast cancer cells impairs their ability to adapt to the brain microenvironment, while increasing SRRM4/RE-1 Silencing Transcription Factor (REST4) levels leads to greater expression of neurotransmitter and synaptic signaling mediators and a significant colonization advantage.

CONCLUSIONS

Collectively, our findings identify SRRM4 as a regulator of brain metastasis colonization, and a potential therapeutic target in breast cancer.

Intratumoral Delivery of Chimeric Antigen Receptor T Cells Targeting CD133 Effectively Treats Brain Metastases

PURPOSE

Brain metastases (BM) are mainly treated palliatively with an expected survival of less than 12 months after diagnosis. In many solid tumors, the human neural stem cell marker glycoprotein CD133 is a marker of a tumor-initiating cell population that contributes to therapy resistance, relapse, and metastasis.

EXPERIMENTAL DESIGN

Here, we use a variant of our previously described CD133 binder to generate second-generation CD133-specific chimeric antigen receptor T cells (CAR-T) to demonstrate its specificity and efficacy against multiple patient-derived BM cell lines with variable CD133 antigen expression.

RESULTS

Using both lung- and colon-BM patient-derived xenograft models, we show that a CD133-targeting CAR-T cell therapy can evoke significant tumor reduction and survival advantage after a single dose, with complete remission observed in the colon-BM model.

CONCLUSIONS

In summary, these data suggest that CD133 plays a critical role in fueling the growth of BM, and immunotherapeutic targeting of this cell population is a feasible strategy to control the outgrowth of BM tumors that are otherwise limited to palliative care. See related commentary by Sloan et al., p. 477.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Integrated genomic and DNA methylation analysis of patients with advanced non-small cell lung cancer with brain metastases

BACKGROUND

Brain metastasis is a common and lethal complication of non-small cell lung cancer (NSCLC). It is mostly diagnosed only after symptoms develop, at which point very few treatment options are available. Therefore, patients who have an increased risk of developing brain metastasis need to be identified early. Our study aimed to identify genomic and epigenomic biomarkers for predicting brain metastasis risk in NSCLC patients.

METHODS

Paired primary lung tumor tissues and either brain metastatic tissues or cerebrospinal fluid (CSF) samples were collected from 29 patients with treatment-naïve advanced NSCLC with central nervous system (CNS) metastases. A control group comprising 31 patients with advanced NSCLC who died without ever developing CNS metastasis was also included. Somatic mutations and DNA methylation levels were examined through capture-based targeted sequencing with a 520-gene panel and targeted bisulfite sequencing with an 80,672 CpG panel.

RESULTS

Compared to primary lung lesions, brain metastatic tissues harbored numerous unique copy number variations. The tumor mutational burden was comparable between brain metastatic tissue (P = 0.168)/CSF (P = 0.445) and their paired primary lung tumor samples. Kelch-like ECH-associated protein (KEAP1) mutations were detected in primary lung tumor and brain metastatic tissue samples of patients with brain metastasis. KEAP1 mutation rate was significantly higher in patients with brain metastasis than those without (P = 0.031). DNA methylation analysis revealed 15 differentially methylated blocks between primary lung tumors of patients with and without CNS metastasis. A brain metastasis risk prediction model based on these 15 differentially methylated blocks had an area under the curve of 0.94, with 87.1% sensitivity and 82.8% specificity.

CONCLUSIONS

Our analyses revealed 15 differentially methylated blocks in primary lung tumor tissues, which can differentiate patients with and without CNS metastasis. These differentially methylated blocks may serve as predictive biomarkers for the risk of developing CNS metastasis in NSCLC. Additional larger studies are needed to validate the predictive value of these markers.

HER2 Receptor Conversion Is a strong Survival Predictor in Patients with Breast Cancer Brain Metastases

BACKGROUND

Hormone and human epidermal growth factor receptor 2 (HER2/neu) receptor status is prognostic and predictive in breast cancer (BC) and guides the choice of therapy. However, owing to receptor conversion, the receptor status can differ in metastases compared with that of the primary tumor. The aim of the present study was to analyze the prognostic value of receptor status, receptor conversion, and clinical parameters in patients with resected BC brain metastases (BMs).

METHODS

Patients with BCBMs treated at our institution from July 2007 to December 2019 were eligible for the present study. The receptor status of the BC and corresponding BMs and the occurrence of receptor conversion were separately recorded for 3 common receptors: HER2/neu, estrogen receptor, and progesterone receptor. The association between the receptor status or receptor conversion and clinical parameters was adjusted for outcome-relevant patient and tumor characteristics.

RESULTS

The final analysis included 78 patients. HER2/neu receptor status in BMs was associated with overall survival (P = 0.033). Receptor conversion was identified in 39 patients (50.0%): HER2/neu, n = 9 (11.5%); estrogen receptor, n = 22 (28.2%); and progesterone receptor, n = 25 (32.1%). In the final multivariate Cox regression analysis, HER2/neu receptor conversion (adjusted hazard ratio [aHR], 3.58; P = 0.006), Karnofsky performance status score <70% (aHR, 3.11; P = 0.048), infratentorial BM location (aHR, 2.49; P = 0.007), and age ≥55 years at BM diagnosis (aHR, 2.20; P = 0.046) were independently associated with poorer survival.

CONCLUSIONS

Of the 3 common BC receptors, only HER2/neu receptor conversion was strongly associated with the prognosis of patients with surgically treated BCBMs. The clinical relevance of the reevaluation of receptor status in BMs favors surgical treatment of patients with noneloquent BCBMs.

PFND1 Predicts Poor Prognosis of Gastric Cancer and Promotes Cell Metastasis by Activating the Wnt/β-Catenin Pathway

Background

Prefoldin (PFDN) subunits have recently been found to function importantly in various tumor types, while the role of PFDN subunit 1 (PFDN1) in gastric cancer (GC) remains largely unknown. Herein, we aimed to investigate the clinical significance, the biological role and the underlying mechanism of PFDN1 in GC development.

Materials and Methods

PFDN1 expression levels were measured in human GC specimens by quantitative real-time PCR (qRT-PCR), Western blot and immunohistochemistry. Furthermore, the effects of aberrant PFDN1 expression on GC cells behavior were assessed by wound-healing assay and transwell assay in vitro, and metastasis assay in nude mice, as well as Wnt/β-catenin signaling-induced epithelial-mesenchymal transition (EMT)-related markers by qRT-PCR and Western blot.

Results

PFDN1 levels were significantly upregulated in GC tissues compared with those in matched adjacent normal tissues. PFDN1 upregulation correlated strongly with clinical metastasis and unfavorable prognosis for GC patients. In vitro and in vivo studies revealed that PFDN1 facilitated GC cell migration, invasion and metastasis. Mechanically, PFDN1 modulated GC cell behavior by activating Wnt/β-catenin signaling-mediated EMT.

Conclusion

These results suggested a central role of PFDN1 in GC metastatic development via the Wnt/β-catenin pathway, thus providing a potential therapeutic target for patients with GC.

Cancer Cell Dormancy in Metastasis

Recurrent metastasis following extended periods of disease-free survival remains a common cause of morbidity and mortality for many cancer patients. Recurrence is thought to be mediated by tumor cells that escaped the primary site early in the disease course and colonize distant organs. In these locations, cells adapt to the local environment, entering a state of long-term dormancy in which they can resist therapy. Then, through mechanisms that are poorly understood, a proportion of these cells are reactivated and become proliferative, forming lethal metastases. Here, we discuss disseminated tumor cell dormancy in recurrent metastasis. We discuss mechanisms known to control entrance of cells into dormancy, highlighting the relevant microenvironments or "niches" in which these cells reside and mechanisms known to be involved in dormant cell reactivation. Finally, we consider emerging therapeutic approaches aimed at eradicating residual disease and preventing metastatic relapse.

In Vivo Murine Models of Brain Metastasis

Metastases are the most common tumor type to affect the adult central nervous system. In vivo modeling of brain metastases provides insight into the mechanisms of metastatic development as well as a clinically relevant therapeutic screening platform. Here we describe the development of a novel mouse model of brain metastasis from a primary lung cancer utilizing primary patient samples. These models provide an accurate representation of different stages of the clinical progression of the disease.

Correlation of Leukocyte Subtypes, Neutrohyl Lymphocyte Ratio, and Functional Outcome in Brain Metastasis

BACKGROUND:

As the most cause of death in patients with solid extracranial malignancy, brain metastasis (BM) nowadays being studied extensively especially on how to find a reliable laboratory marker that can correlate with its clinical outcome. Leukocyte subtypes, primarily neutrophils and lymphocytes and its ratio known as Neutrophils-Lymphocyte Ratio (NLR) have been known before its relationship with progressivity of BM from other solid tumours.

AIM:

The objectives of this research to study the correlation of leukocyte subtypes, neutrophil-lymphocyte ratio & functional outcome in brain metastasis.

METHODS:

The study subjects were recruited consecutively from the study population. Venous blood was taken 5 ml of venous blood samples done in the first day of admission on emergency department and neurology clinic of Neurology Department of Adam Malik General Hospital before any drug injections. Samples were kept in vacutainer tubes containing ethylenediaminetetraacetic acid (EDTA) and sent to Department of Clinical Pathology laboratory of Adam Malik General Hospital, immediately centrifuged at 3100 rpm for 10 minutes in -20°C temperature and analysed using Sysmex XT-2000i. Functional outcome of the patient assessed using Karnofsky performance scale (KPS) in a cross-sectional manner with laboratory analysis.

RESULTS:

We conduct a mean differences and correlational leukocytes and its subsets analysis of 72 BM patients resulting on significant positive correlation on lymphocyte percentage (r = 0.383, p = 0.001) and lymphocyte absolute (r = 0.265, p = 0.024), also significant negative correlation on neutrophils (r = -0.240, p = 0.042) and NLR (r = -0.432, p < 0.001) with Karnofsky Performance Scale (KPS).

CONCLUSION:

Increased lymphocyte absolute and lymphocyte percentage correlated significantly (p < 0.05) with better KPS, while elevated neutrophils percentage and increased NLR show significant correlation with worse outcome of BM patients.

Comprehensive molecular biomarker identification in breast cancer brain metastases

Background

Breast cancer brain metastases (BCBM) develop in about 20–30% of breast cancer (BC) patients. BCBM are associated with dismal prognosis not at least due to lack of valuable molecular therapeutic targets. The aim of the study was to identify new molecular biomarkers and targets in BCBM by using complementary state-of-the-art techniques.

Methods

We compared array expression profiles of three BCBM with 16 non-brain metastatic BC and 16 primary brain tumors (prBT) using a false discovery rate (FDR) p < 0.05 and fold change (FC) > 2. Biofunctional analysis was conducted on the differentially expressed probe sets. High-density arrays were employed to detect copy number variations (CNVs) and whole exome sequencing (WES) with paired-end reads of 150 bp was utilized to detect gene mutations in the three BCBM.

Results

The top 370 probe sets that were differentially expressed between BCBM and both BC and prBT were in the majority comparably overexpressed in BCBM and included, e.g. the coding genes BCL3, BNIP3, BNIP3P1, BRIP1, CASP14, CDC25A, DMBT1, IDH2, E2F1, MYCN, RAD51, RAD54L, and VDR. A number of small nucleolar RNAs (snoRNAs) were comparably overexpressed in BCBM and included SNORA1, SNORA2A, SNORA9, SNORA10, SNORA22, SNORA24, SNORA30, SNORA37, SNORA38, SNORA52, SNORA71A, SNORA71B, SNORA71C, SNORD13P2, SNORD15A, SNORD34, SNORD35A, SNORD41, SNORD53, and SCARNA22. The top canonical pathway was entitled, role of BRCA1 in DNA damage response. Network analysis revealed key nodes as Akt, ERK1/2, NFkB, and Ras in a predicted activation stage. Downregulated genes in a data set that was shared between BCBM and prBT comprised, e.g. BC cell line invasion markers JUN, MMP3, TFF1, and HAS2. Important cancer genes affected by CNVs included TP53, BRCA1, BRCA2, ERBB2, IDH1, and IDH2. WES detected numerous mutations, some of which affecting BC associated genes as CDH1, HEPACAM, and LOXHD1.

Conclusions

Using complementary molecular genetic techniques, this study identified shared and unshared molecular events in three highly aberrant BCBM emphasizing the challenge to detect new molecular biomarkers and targets with translational implications. Among new findings with the capacity to gain clinical relevance is the detection of overexpressed snoRNAs known to regulate some critical cellular functions as ribosome biogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12967-017-1370-x) contains supplementary material, which is available to authorized users.

RNAi screen identifies essential regulators of human brain metastasis-initiating cells

Brain metastases (BM) are the most common brain tumor in adults and are a leading cause of cancer mortality. Metastatic lesions contain subclones derived from their primary lesion, yet their functional characterization is limited by a paucity of preclinical models accurately recapitulating the metastatic cascade, emphasizing the need for a novel approach to BM and their treatment. We identified a unique subset of stem-like cells from primary human patient brain metastases, termed brain metastasis-initiating cells (BMICs). We now establish a BMIC patient-derived xenotransplantation (PDXT) model as an investigative tool to comprehensively interrogate human BM. Using both in vitro and in vivo RNA interference screens of these BMIC models, we identified SPOCK1 and TWIST2 as essential BMIC regulators. SPOCK1 in particular is a novel regulator of BMIC self-renewal, modulating tumor initiation and metastasis from the lung to the brain. A prospective cohort of primary lung cancer specimens showed that SPOCK1 was overexpressed only in patients who ultimately developed BM. Protein-protein interaction network mapping between SPOCK1 and TWIST2 identified novel pathway interactors with significant prognostic value in lung cancer patients. Of these genes, INHBA, a TGF-β ligand found mutated in lung adenocarcinoma, showed reduced expression in BMICs with knockdown of SPOCK1. In conclusion, we have developed a useful preclinical model of BM, which has served to identify novel putative BMIC regulators, presenting potential therapeutic targets that block the metastatic process, and transform a uniformly fatal systemic disease into a locally controlled and eminently more treatable one.

Preclinical Modeling and Therapeutic Avenues for Cancer Metastasis to the Central Nervous System

Metastasis is the dissemination of cells from the primary tumor to other locations within the body, and continues to be the predominant cause of death among cancer patients. Metastatic progression within the adult central nervous system is 10 times more frequent than primary brain tumors. Metastases affecting the brain parenchyma and leptomeninges are associated with grave prognosis, and even after successful control of the primary tumor the median survival is a dismal 2-3 months with treatment options typically limited to palliative care. Current treatment options for brain metastases (BM) and disseminated brain tumors are scarce, and the improvement of novel targeted therapies requires a broader understanding of the biological complexity that characterizes metastatic progression. In this review, we provide insight into patterns of BM progression and leptomeningeal spread, outlining the development of clinically relevant in vivo models and their contribution to the discovery of innovative cancer therapies. In vivo models paired with manipulation of in vitro methods have expanded the tools available for investigators to develop agents that can be used to prevent or treat metastatic disease. The knowledge gained from the use of such models can ultimately lead to the prevention of metastatic dissemination and can extend patient survival by transforming a uniformly fatal systemic disease into a locally controlled and eminently more treatable one.

EMT: Mechanisms and therapeutic implications

Metastasis, the dissemination of cancer cells from primary tumors, represents a major hurdle in the treatment of cancer. The epithelial-mesenchymal transition (EMT) has been studied in normal mammalian development for decades, and it has been proposed as a critical mechanism during cancer progression and metastasis. EMT is tightly regulated by several internal and external cues that orchestrate the shifting from an epithelial-like phenotype into a mesenchymal phenotype, relying on a delicate balance between these two stages to promote metastatic development. EMT is thought to be induced in a subset of metastatic cancer stem cells (MCSCs), bestowing this population with the ability to spread throughout the body and contributing to therapy resistance. The EMT pathway is of increasing interest as a novel therapeutic avenue in the treatment of cancer, and could be targeted to prevent tumor cell dissemination in early stage patients or to eradicate existing metastatic cells in advanced stages. In this review, we describe the sequence of events and defining mechanisms that take place during EMT, and how these interactions drive cancer cell progression into metastasis. We summarize clinical interventions focused on targeting various aspects of EMT and their contribution to preventing cancer dissemination.

Microarray expression profiling identifies genes, including cytokines, and biofunctions, as diapedesis, associated with a brain metastasis from a papillary thyroid carcinoma

Brain metastatic papillary thyroid carcinomas (PTCs) are afflicted with unfavorable prognosis; however, the underlying molecular genetics of these rare metastases are virtually unknown. In this study, we compared whole transcript microarray expression profiles of a BRAF mutant, brain metastasis from a PTC, including its technical replicate (TR), with eight non-brain metastatic PTCs and eight primary brain tumors. The top 95 probe sets (false discovery rate (FDR) p-value < 0.05 and fold change (FC) > 2) that were differentially expressed between the brain metastatic PTC, including the TR, and both, non-brain metastatic PTCs and primary brain tumors were in the vast majority upregulated and comprise, e.g. ROS1, MYBPH, SLC18A3, HP, SAA2-SAA4, CP, CCL20, GFAP, RNU1-120P, DMBT1, XDH, CXCL1, PI3, and NAPSA. Cytokines were represented by 10 members in the top 95 probe sets. Pathway and network analysis (p-value < 0.05 and FC > 2) identified granulocytes adhesion and diapedesis as top canonical pathway. Most significant upstream regulators were lipopolysaccharide, TNF, NKkB (complex), IL1A, and CSF2. Top networks categorized under diseases & functions were entitled migration of cells, cell movement, cell survival, apoptosis, and proliferation of cells. Probe sets that were significantly shared between the brain metastatic PTC, the TR, and primary brain tumors include CASP1, CASP4, C1R, CC2D2B, RNY1P16, WDR72, LRRC2, ZHX2, CITED1, and the noncoding transcript AK128523. Taken together, this study identified a set of candidate genes and biofunctions implicated in, so far nearly uncharacterized, molecular processes of a brain metastasis from a PTC.

Fenretinide (4-HPR) Targets Caspase-9, ERK 1/2 and the Wnt3a/β-Catenin Pathway in Medulloblastoma Cells and Medulloblastoma Cell Spheroids

Medulloblastoma (MB), a neuroectodermal tumor arising in the cerebellum, represents the most frequent childhood brain malignancy. Current treatments for MB combine radiation and chemotherapy and are often associated with relevant side effects; novel therapeutic strategies are urgently needed. N-(4-Hydroxyphenyl) retinamide (4-HPR, fenretinide), a synthetic analogue of all-trans retinoic acid, has emerged as a promising and well-tolerated cancer chemopreventive and chemotherapeutic agent for various neoplasms, from breast cancer to neuroblastoma. Here we investigated the effects of 4-HPR on MB cell lines and identified the mechanism of action for a potential use in therapy of MB. Flow cytometry analysis was performed to evaluate 4-HPR induction of apoptosis and oxygen reactive species (ROS) production, as well as cell cycle effects. Functional analysis to determine 4-HPR ability to interfere with MB cell migration and invasion were performed. Western Blot analysis were used to investigate the crucial molecules involved in selected signaling pathways associated with apoptosis (caspase-9 and PARP-1), cell survival (ERK 1/2) and tumor progression (Wnt3a and β-catenin). We show that 4-HPR induces caspase 9-dependent cell death in DAOY and ONS-76 cells, associated with increased ROS generation, suggesting that free radical intermediates might be directly involved. We observed 4-HPR induction of cell cycle arrest in G1/S phase, inactivated β-catenin, and inhibition of MB cell migration and invasion. We also evaluated the ability of 4-HPR to target MB cancer-stem/cancer-initiating cells, using an MB spheroids model, followed by flow cytometry and quantitative real-time PCR. 4-HPR treatment reduced DAOY and ONS-76 spheroid formation, in term of number and size. Decreased expression of the surface markers CD133⁺ and ABCG2⁺ as well as Oct-4 and Sox-2 gene expression were observed on BTICs treated with 4-HPR further reducing BITIC invasive activities. Finally, we analyzed 4-HPR ability to inhibit MB tumor cell growth in vivo in nude mice. Taken together, our data suggest that 4-HPR targets both parental and MB tumor stem/initiating cell-like populations. Since 4-HPR exerts low toxicity, it could represent a valid compound in the treatment of human MB.

A Quantitative System for Studying Metastasis Using Transparent Zebrafish

Metastasis is the defining feature of advanced malignancy, yet remains challenging to study in laboratory environments. Here, we describe a high-throughput zebrafish system for comprehensive, in vivo assessment of metastatic biology. First, we generated several stable cell lines from melanomas of transgenic mitfa-BRAF(V600E);p53(-/-) fish. We then transplanted the melanoma cells into the transparent casper strain to enable highly quantitative measurement of the metastatic process at single-cell resolution. Using computational image analysis of the resulting metastases, we generated a metastasis score, μ, that can be applied to quantitative comparison of metastatic capacity between experimental conditions. Furthermore, image analysis also provided estimates of the frequency of metastasis-initiating cells (∼1/120,000 cells). Finally, we determined that the degree of pigmentation is a key feature defining cells with metastatic capability. The small size and rapid generation of progeny combined with superior imaging tools make zebrafish ideal for unbiased high-throughput investigations of cell-intrinsic or microenvironmental modifiers of metastasis. The approaches described here are readily applicable to other tumor types and thus serve to complement studies also employing murine and human cell culture systems.

Evolution of multidisciplinary brain metastasis management: case study and literature review

Up to 40 percent of all cancer patients develop brain metastasis (BM) during the course of their disease. Despite advances in diagnosis and therapy, prognosis in patients with BM remains poor for many patients, but for some, survival can be of the order of several years in duration. Difficulty in predicting long-term survivors has created controversy in contemporary management of BM. Minimizing medical and neurocognitive side effects (disease borne or iatrogenic) to enhance functional independence and improving overall quality of life in these individuals requires a coordinated approach of first-line and salvage surgical, chemotherapeutic (cytotoxic, targeted, or immune based), and radiation (whole brain radiotherapy or stereotactic radiosurgery) modalities. This goal needs to be balanced against the more traditional targets of management such as symptom relief, reducing tumor burden, and local tumor control, thereby increasing progression-free survival. This case study and literature review demonstrates the role of various treatment modalities in the management of BM.