Host genetics influence tumour metastasis

Prostate cancer metastasis and health disparities: a systematic review

BACKGROUND

Prostate cancer (PCa), one of the most prevalent malignancies affecting men, significantly contributes to increased mortality rates worldwide. While the causative death is due to advanced metastatic disease, this occurrence disproportionately impacts men of African descent compared to men of European descent. In this review, we describe potential mechanisms underlying PCa metastases disparities and current treatments for metastatic disease among these populations, differences in treatment outcomes, and survival rates, in hopes of highlighting a need to address disparities in PCa metastases.

METHODS

We reviewed existing literature using databases such as PubMed, Google Scholar, and Science Direct using the following keywords: "prostate cancer metastases", "metastatic prostate cancer disparity", "metastatic prostate cancer diagnosis and treatment", "prostate cancer genetic differences and mechanisms", "genetic differences and prostate tumor microenvironment", and "men of African descent and access to clinical treatments". The inclusion criteria for literature usage were original research articles and review articles.

RESULTS

Studies indicate unique genetic signatures and molecular mechanisms such as Epithelial-Mesenchymal Transition (EMT), inflammation, and growth hormone signaling involved in metastatic PCa disparities. Clinical studies also demonstrate differences in treatment outcomes that are race-specific, for example, patients of African descent have a better response to enzalutamide and immunotherapy yet have less access to these drugs as compared to patients of European descent.

CONCLUSIONS

Growing evidence suggests a connection between a patient's genetic profile, the prostate tumor microenvironment, and social determinants of health that contribute to the aggressiveness of metastatic disease and treatment outcomes. With several potential pathways highlighted, the limitations in current diagnostic and therapeutic applications that target disparity in PCa metastases warrant rigorous research attention.

Interleukins (Cytokines) as Biomarkers in Colorectal Cancer: Progression, Detection, and Monitoring

Cancer is the primary cause of death in economically developed countries and the second leading cause in developing countries. Colorectal cancer (CRC) is the third most common cause of cancer-related deaths worldwide. Risk factors for CRC include obesity, a diet low in fruits and vegetables, physical inactivity, and smoking. CRC has a poor prognosis, and there is a critical need for new diagnostic and prognostic biomarkers to reduce related deaths. Recently, studies have focused more on molecular testing to guide targeted treatments for CRC patients. The most crucial feature of activated immune cells is the production and release of growth factors and cytokines that modulate the inflammatory conditions in tumor tissues. The cytokine network is valuable for the prognosis and pathogenesis of colorectal cancer as they can aid in the cost-effective and non-invasive detection of cancer. A large number of interleukins (IL) released by the immune system at various stages of CRC can act as "biomarkers". They play diverse functions in colorectal cancer, and include IL-4, IL-6, IL-8, IL-11, IL-17A, IL-22, IL-23, IL-33, TNF, TGF-β, and vascular endothelial growth factor (VEGF), which are pro-tumorigenic genes. However, there are an inadequate number of studies in this area considering its correlation with cytokine profiles that are clinically useful in diagnosing cancer. A better understanding of cytokine levels to establish diagnostic pathways entails an understanding of cytokine interactions and the regulation of their various biochemical signaling pathways in healthy individuals. This review provides a comprehensive summary of some interleukins as immunological biomarkers of CRC.

Comparison of Database Searching Programs for the Analysis of Single-Cell Proteomics Data

Single-cell proteomics is emerging as an important subfield in the proteomics and mass spectrometry communities, with potential to reshape our understanding of cell development, cell differentiation, disease diagnosis, and the development of new therapies. Compared with significant advancements in the "hardware" that is used in single-cell proteomics, there has been little work comparing the effects of using different "software" packages to analyze single-cell proteomics datasets. To this end, seven popular proteomics programs were compared here, applying them to search three single-cell proteomics datasets generated by three different platforms. The results suggest that MSGF+, MSFragger, and Proteome Discoverer are generally more efficient in maximizing protein identifications, that MaxQuant is better suited for the identification of low-abundance proteins, that MSFragger is superior in elucidating peptide modifications, and that Mascot and X!Tandem are better for analyzing long peptides. Furthermore, an experiment with different loading amounts was carried out to investigate changes in identification results and to explore areas in which single-cell proteomics data analysis may be improved in the future. We propose that this comparative study may provide insight for experts and beginners alike operating in the emerging subfield of single-cell proteomics.

Discovering Innate Driver Variants for Risk Assessment of Early Colorectal Cancer Metastasis

Metastasis is the main fatal cause of colorectal cancer (CRC). Although enormous efforts have been made to date to identify biomarkers associated with metastasis, there is still a huge gap to translate these efforts into effective clinical applications due to the poor consistency of biomarkers in dealing with the genetic heterogeneity of CRCs. In this study, a small cohort of eight CRC patients was recruited, from whom we collected cancer, paracancer, and normal tissues simultaneously and performed whole-exome sequencing. Given the exomes, a novel statistical parameter LIP was introduced to quantitatively measure the local invasion power for every somatic and germline mutation, whereby we affirmed that the innate germline mutations instead of somatic mutations might serve as the major driving force in promoting local invasion. Furthermore, via bioinformatic analyses of big data derived from the public zone, we identified ten potential driver variants that likely urged the local invasion of tumor cells into nearby tissue. Of them, six corresponding genes were new to CRC metastasis. In addition, a metastasis resister variant was also identified. Based on these eleven variants, we constructed a logistic regression model for rapid risk assessment of early metastasis, which was also deployed as an online server, AmetaRisk (http://www.bio-add.org/AmetaRisk). In summary, we made a valuable attempt in this study to exome-wide explore the genetic driving force to local invasion, which provides new insights into the mechanistic understanding of metastasis. Furthermore, the risk assessment model can assist in prioritizing therapeutic regimens in clinics and discovering new drug targets, and thus substantially increase the survival rate of CRC patients.

UACA locus is associated with breast cancer chemoresistance and survival

Few germline genetic variants have been robustly linked with breast cancer outcomes. We conducted trans-ethnic meta genome-wide association study (GWAS) of overall survival (OS) in 3973 breast cancer patients from the Pathways Study, one of the largest prospective breast cancer survivor cohorts. A locus spanning the UACA gene, a key regulator of tumor suppressor Par-4, was associated with OS in patients taking Par-4 dependent chemotherapies, including anthracyclines and anti-HER2 therapy, at a genome-wide significance level (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P = 1.27 \times 10^{ - 9}$$\end{document}P=1.27×10−9). This association was confirmed in meta-analysis across four independent prospective breast cancer cohorts (combined hazard ratio = 1.84, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P = 1.28 \times 10^{ - 11}$$\end{document}P=1.28×10−11). Transcriptome-wide association study revealed higher UACA gene expression was significantly associated with worse OS (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P = 4.68 \times 10^{ - 7}$$\end{document}P=4.68×10−7). Our study identified the UACA locus as a genetic predictor of patient outcome following treatment with anthracyclines and/or anti-HER2 therapy, which may have clinical utility in formulating appropriate treatment strategies for breast cancer patients based on their genetic makeup.

Recent Advances in Electrical Impedance Sensing Technology for Single-Cell Analysis

Cellular heterogeneity is of significance in cell-based assays for life science, biomedicine and clinical diagnostics. Electrical impedance sensing technology has become a powerful tool, allowing for rapid, non-invasive, and label-free acquisition of electrical parameters of single cells. These electrical parameters, i.e., equivalent cell resistance, membrane capacitance and cytoplasm conductivity, are closely related to cellular biophysical properties and dynamic activities, such as size, morphology, membrane intactness, growth state, and proliferation. This review summarizes basic principles, analytical models and design concepts of single-cell impedance sensing devices, including impedance flow cytometry (IFC) to detect flow-through single cells and electrical impedance spectroscopy (EIS) to monitor immobilized single cells. Then, recent advances of both electrical impedance sensing systems applied in cell recognition, cell counting, viability detection, phenotypic assay, cell screening, and other cell detection are presented. Finally, prospects of impedance sensing technology in single-cell analysis are discussed.

Association of germline genetic variants with breast cancer-specific survival in patient subgroups defined by clinic-pathological variables related to tumor biology and type of systemic treatment

BACKGROUND

Given the high heterogeneity among breast tumors, associations between common germline genetic variants and survival that may exist within specific subgroups could go undetected in an unstratified set of breast cancer patients.

METHODS

We performed genome-wide association analyses within 15 subgroups of breast cancer patients based on prognostic factors, including hormone receptors, tumor grade, age, and type of systemic treatment. Analyses were based on 91,686 female patients of European ancestry from the Breast Cancer Association Consortium, including 7531 breast cancer-specific deaths over a median follow-up of 8.1 years. Cox regression was used to assess associations of common germline variants with 15-year and 5-year breast cancer-specific survival. We assessed the probability of these associations being true positives via the Bayesian false discovery probability (BFDP < 0.15).

RESULTS

Evidence of associations with breast cancer-specific survival was observed in three patient subgroups, with variant rs5934618 in patients with grade 3 tumors (15-year-hazard ratio (HR) [95% confidence interval (CI)] 1.32 [1.20, 1.45], P = 1.4E-08, BFDP = 0.01, per G allele); variant rs4679741 in patients with ER-positive tumors treated with endocrine therapy (15-year-HR [95% CI] 1.18 [1.11, 1.26], P = 1.6E-07, BFDP = 0.09, per G allele); variants rs1106333 (15-year-HR [95% CI] 1.68 [1.39,2.03], P = 5.6E-08, BFDP = 0.12, per A allele) and rs78754389 (5-year-HR [95% CI] 1.79 [1.46,2.20], P = 1.7E-08, BFDP = 0.07, per A allele), in patients with ER-negative tumors treated with chemotherapy.

CONCLUSIONS

We found evidence of four loci associated with breast cancer-specific survival within three patient subgroups. There was limited evidence for the existence of associations in other patient subgroups. However, the power for many subgroups is limited due to the low number of events. Even so, our results suggest that the impact of common germline genetic variants on breast cancer-specific survival might be limited.

Cytochrome P450 1B1 polymorphism drives cancer cell stemness and patient outcome in head-and-neck carcinoma

Background

Cytochrome P450 1B1 (CYP1B1) is mostly expressed in tumours and displays unusual properties. Its two polymorphic forms were differently associated with anticancer drug sensitivity. We decipher here the role of this polymorphism in anticancer drug efficacy in vitro, in vivo and in the clinical setting.

Methods

From head-and-neck squamous cell carcinoma cell lines not expressing CYP1B1, we generated isogenic derivatives expressing the two forms. Proliferation, invasiveness, stem cell characteristics, sensitivity to anticancer agents and transcriptome were analysed. Tumour growth and chemosensitivity were studied in vivo. A prospective clinical trial on 121 patients with advanced head-and-neck cancers was conducted, and a validation-retrospective study was conducted.

Results

Cell lines expressing the variant form displayed high rates of in vitro proliferation and invasiveness, stemness features and resistance to DNA-damaging agents. In vivo, tumours expressing the variant CYP1B1 had higher growth rates and were markedly drug-resistant. In the clinical study, overall survival was significantly associated with the genotypes, wild-type patients presenting a longer median survival (13.5 months) than the variant patients (6.3 months) (p = 0.0166).

Conclusions

This frequent CYP1B1 polymorphism is crucial for cancer cell proliferation, migration, resistance to chemotherapy and stemness properties, and strongly influences head-and-neck cancer patients’ survival.

MicroRNA-3648 Is Upregulated to Suppress TCF21, Resulting in Promotion of Invasion and Metastasis of Human Bladder Cancer

Although microRNAs (miRNAs) are well-known for their potential in cancer, the function and mechanisms of miR-3648 have barely been explored in any type of cancer. We show here that miR-3648 is upregulated in human BC tissues in comparison with adjacent non-tumor tissues. Functional studies showed that inhibition of miR-3648 expression in the human invasive BC UMUC3 and T24T cell lines decreased migration and invasion in vitro and suppressed lung metastasis in vivo, whereas miR-3648 overexpression promoted BC cell migration and invasion. A bioinformatics screen and mRNA 3' UTR luciferase reporter assay showed that transcription factor 21 (TCF21) was a direct target of miR-3648, and the results obtained from using a miR-3648 inhibitor revealed that miR-3648 inhibited TCF21 protein expression by reduction of its mRNA stability. Further, Kisspeptin 1 (KISS1) was identified as a TCF21 downstream effector responsible for miR-3648-mediated BC invasion and lung metastasis. Collectively, the present results suggest that miR-3648 is overexpressed and plays an oncogenic role in mediation of BC invasion and metastasis through directing the TCF21/KISS1 axis, revealing miR-3648 as a potential biomarker for BC prognosis and a target for BC therapy.

Correlation of two distinct metastasis-associated proteins, MTA1 and S100A4, in angiogenesis for promoting tumor growth

Extensive studies on metastasis-associated proteins, S100A4 and MTA1, have been carried out for over two decades, but correlation of both proteins remains obscure. Here we show evidence for the correlation in angiogenesis. First, silencing of each protein by siRNA-mediated knockdown in mouse endothelial MSS31 cells resulted in the inhibition of tube formation. Unexpectedly, the knockdown of MTA1 affected not only its own expression but also the expression of S100A4, whereas silencing of S100A4 did not affect the MTA1 expression. Additionally, non-muscle myosin IIA (NMIIA) phosphorylation, which was partly controlled by S100A4, was found to be upregulated by knockdown of both proteins in MSS31 cells. Moreover, cycloheximide treatment of MSS31 cells revealed that the rate of S100A4 degradation was accelerated by MTA1 knockdown. This finding, together with our observation that cytoplasmic MTA1, but not nuclear MTA1, was colocalized with S100A4, suggested the involvement of MTA1 in S100A4 stability. The direct in vivo angiogenesis assay showed that both protein siRNAs provoked a significant inhibition of new blood vessel formation induced by angiogenic factors, indicating their anti-angiogenic activities. Treatment of human pancreatic tumor (PANC-1) xenograft in mice with mMTA1 siRNA resulted in tumor regression via suppression of angiogenesis in vivo, as also observed in the case of human prostate cancer xenograft treated with mS100A4 siRNA. Taken together, these data led us to conclude that the MTA1-S100A4-NMIIA axis exists in endothelial cells as a novel pathway in promoting tumor vascular formation and could be a target for suppressing tumor growth and metastasis.

Lymph node metastasis in oral cancer is strongly associated with chromosomal instability and DNA repair defects

Oral squamous cell carcinoma (OSCC) is highly prevalent in south and southeast Asia. Many (30-50%) OSCC patients develop lymph node metastasis (LNM), which is the most important prognostic factor in OSCC. To identify genomic correlates of LNM, we compared exome sequences and copy number variation data of blood and tumor DNA from highly contrasting subgroups of patients to reduce false inferences-(i) patients with LNM and (ii) patients with late stage disease but without LNM. We found that LNM is associated with (i) specific hotspot somatic mutations in TP53 and CASP8; (ii) rare nonsilent germline mutations in BRCA2 and FAT1; (iii) mutations in mito-G2/M and nonhomologous end joining (NHEJ) pathways; (iv) recurrent deletion of genes for DNA repair by homologous recombination; and (v) chromosomal instability. LN+ patients with NHEJ pathway mutations have longer disease-free survival. Five genomic features have a high predictive value of LNM.

A single-cell translocation and secretion assay (TransSeA)

Understanding biological heterogeneity at the single cell level is required for advancing insights into the complexity of human physiology and diseases. While advances in technological and analytical methods have afforded unprecedented glimpses of this heterogeneity, the information captured to date largely represents one-time "snap" shots of single cell physiology. To address the limits of existing methods and to accelerate discoveries from single cell studies, we developed a single-cell translocation and secretion assay (TransSeA) that supports time lapse analysis, enables molecular cargo analysis of secretions such as extracellular vesicles (EVs) from single cells, allows massively parallel single cell transfer according to user-defined cell selection criteria, and supports tracking of phenotypes between parental and progeny cells derived from single cells. To demonstrate the unique capabilities and efficiencies of the assay, we present unprecedented single cell studies related to cell secretions, EV cargos and cell intrinsic properties. Although used as examples to demonstrate the feasibility and versatility of the technology, the studies already provided insights into key unanswered questions such as the microRNAs carried by EVs, the relationships between EV secretion rates and gene expressions, and the spontaneous, trans-generational phenotypic changes in EV secretion between parental and progeny cells.

Generation and characterisation of two D2A1 mammary cancer sublines to model spontaneous and experimental metastasis in a syngeneic BALB/c host

Studying the complex mechanisms underlying breast cancer metastasis and therapy response necessitates relevant in vivo models, particularly syngeneic models with an intact immune system. Two syngeneic spontaneously metastatic sublines, D2A1-m1 and D2A1-m2, were generated from the poorly metastasising BALB/c-derived D2A1 cell line by serial in vivo passaging. In vivo and in vitro analyses revealed distinct and shared characteristics of the metastatic D2A1-m1 and D2A1-m2 sublines. In particular, D2A1-m1 cells are more aggressive in experimental metastasis assays, while D2A1-m2 cells are more efficient at disseminating from the primary tumour in spontaneous metastasis assays. Surprisingly, classical metastasis-associated in vitro phenotypes, such as enhanced proliferation, migration and invasion, are reduced in the sublines compared to the parental cell line. Further, evasion of immune control cannot fully explain their enhanced metastatic properties. By contrast, both sublines show increased resistance to apoptosis when cultured in non-adherent conditions and, for the D2A1-m2 subline, increased 3D tumour spheroid growth. Moreover, the enhanced spontaneous metastatic phenotype of the D2A1-m2 subline is associated with an increased ability to recruit an activated tumour stroma. The metastatic D2A1-m1 and D2A1-m2 cell lines provide additional syngeneic models for investigating the different steps of the metastatic cascade and thereby represent valuable tools for breast cancer researchers. Finally, this study highlights that morphology and cell behaviour in 2D cell-based assays cannot be used as a reliable predictor of metastatic behaviour in vivo.

Summary: We describe two D2A1 mouse mammary cancer sublines with enhanced spontaneous metastasis in a syngeneic host, and highlight the limitations of in vitro assays to predict in vivo metastatic behaviour.

Mitochondrial Haplotype Alters Mammary Cancer Tumorigenicity and Metastasis in an Oncogenic Driver-Dependent Manner

Using a novel mouse model, a mitochondrial-nuclear exchange model termed MNX, we tested the hypothesis that inherited mitochondrial haplotypes alter primary tumor latency and metastatic efficiency. Male FVB/N-Tg(MMTVneu)202Mul/J (Her2) transgenic mice were bred to female MNX mice having FVB/NJ nuclear DNA with either FVB/NJ, C57BL/6J, or BALB/cJ mtDNA. Pups receiving the C57BL/6J or BALB/cJ mitochondrial genome (i.e., females crossed with Her2 males) showed significantly (P < 0.001) longer tumor latency (262 vs. 293 vs. 225 days), fewer pulmonary metastases (5 vs. 7 vs. 15), and differences in size of lung metastases (1.2 vs. 1.4 vs. 1.0 mm diameter) compared with FVB/NJ mtDNA. Although polyoma virus middle T-driven tumors showed altered primary and metastatic profiles in previous studies, depending upon nuclear and mtDNA haplotype, the magnitude and direction of changes were not the same in the HER2-driven mammary carcinomas. Collectively, these results establish mitochondrial polymorphisms as quantitative trait loci in mammary carcinogenesis, and they implicate distinct interactions between tumor drivers and mitochondria as critical modifiers of tumorigenicity and metastasis. Cancer Res; 77(24); 6941-9. ©2017 AACR.

Cancer metastasis - tricks of the trade

Decades of cancer research have unraveled genetic, epigenetic and molecular pathways leading to plausible therapeutic targets; many of which hold great promise in improving clinical outcomes. Metastatic tumors become evident early on and are one of the major causes of cancer-related fatalities worldwide. This review depicts the sequential events of cancer metastasis. Genetic and epigenetic heterogeneity influences local tumor cell invasion, intravasation, survival in circulation, extravasation and colonization to distant sites. Each sequential event is associated with heterogeneous tumor microenvironment, gain of competence, unique population of cancer stem cells (CSCs), circulatory pathway, compatible niche and immune system support. A tight regulation of metastasis-promoting mechanisms and, in parallel, evading inhibitory mechanisms contribute to the severity and site of metastasis. A comprehensive understanding of tumor cell fate as an individual entity, as well as in combination with different promoting factors and associated molecular mechanisms, is anticipated in the coming years. This will enable scientists to depict design strategies for targeted cancer therapies.

TNF-α -308 A allele is associated with an increased risk of distant metastasis in rectal cancer patients from Southwestern China

Tumor necrosis factor-α (TNF-α), an important factor in systematic inflammation, is reportedly involved in several cancer types. The TNF-α -308 G>A (rs1800629) polymorphism in the promoter region influences TNF-α production. The association between TNF-α -308 G>A polymorphism and colorectal cancer (CRC) is not fully understood, especially the connections between TNF-α -308 G>A polymorphism and clinical features of CRC. In this study, TNF-α -308 G>A polymorphism was genotyped in 1140 individuals with or without CRC from Southwestern China. In case-control studies, we found no association between TNF-α -308 G>A polymorphism and CRC risk. Analysis of the correlations between TNF-α -308 G>A polymorphism and clinical features of CRC revealed that TNF-α -308 A allele was associated with higher body mass index (BMI) larger tumor size, and distant tumor metastasis in all CRC patients. Notably, rectal cancer (a subtype of CRC) patients with TNF-α -308 A allele had a very high risk of distant tumor metastasis [odds ratio (OR) = 4.481; 95% confidence interval (CI): 2.072–9.693; P = 0.00025]. The association between TNF-α -308 A allele and distant tumor metastasis remained even significant after adjusting all clinical characteristics (OR = 7.099; 95% CI: 2.482–20.301; P = 0.000256) in rectal cancer patients. Our results suggested that TNF-α -308 A allele was significantly associated with distant tumor metastasis in rectal cancer patients.

Complex network-based approaches to biomarker discovery

Many studies on biomarker discovery have been done by analyzing mutations in DNA sequences and differences in gene expression patterns. As a new branch of the latter approach, the concept of network biomarkers has been proposed, in which expression data of small subnetworks are used as markers. Furthermore, network biomarkers have been extended to dynamical network biomarkers, in which time series expression data of subnetworks are used as markers. On the other hand, the methodologies in complex networks have also been applied to biomarker discovery. For example, various centrality measures and the concept of observability have been applied. In this article, we review these new approaches for biomarker discovery with focusing on the computational/methodological aspects.

[Blood-based Tumor Markers in Lung Cancer]

In recent years, "liquid biopsy" received enormous attention as a new detecting method. As a non-invasive tumor screening method, the applications of liquid biopsy include early detection, monitoring relapse, assessment of therapy and molecule expression in lung cancer. The main source of liquid biopsy comes from circulating tumor cells (CTCs), ctDNA, and so on. This review will explore the biological characteristics, detection technologies and clinical applications of CTCs, ctDNA and other tumor markers in lung cancer and summarize liquid biopsy which in accord with three important criteria of high sensitivity (high specificity), clinical utility and repeatability, especially a new method of ligand-targeted PCR (LT-PCR) that showed a high sensitivity of 67.2% in stage I lung cancer. We expect that "liquid biopsy" could be really explored from scientific research to clinical application.

Niche inheritance: a cooperative pathway to enhance cancer cell fitness through ecosystem engineering

Cancer cells can be described as an invasive species that is able to establish itself in a new environment. The concept of niche construction can be utilized to describe the process by which cancer cells terraform their environment, thereby engineering an ecosystem that promotes the genetic fitness of the species. Ecological dispersion theory can then be utilized to describe and model the steps and barriers involved in a successful diaspora as the cancer cells leave the original host organ and migrate to new host organs to successfully establish a new metastatic community. These ecological concepts can be further utilized to define new diagnostic and therapeutic areas for lethal cancers. 115: 1478–1485, 2014. © 2014 Wiley Periodicals, Inc.

CXM: a new tool for mapping breast cancer risk in the tumor microenvironment

The majority of causative variants in familial breast cancer remain unknown. Of the known risk variants, most are tumor cell autonomous, and little attention has been paid yet to germline variants that may affect the tumor microenvironment. In this study, we developed a system called the Consomic Xenograft Model (CXM) to map germline variants that affect only the tumor microenvironment. In CXM, human breast cancer cells are orthotopically implanted into immunodeficient consomic strains and tumor metrics are quantified (e.g., growth, vasculogenesis, and metastasis). Because the strain backgrounds vary, whereas the malignant tumor cells do not, any observed changes in tumor progression are due to genetic differences in the nonmalignant microenvironment. Using CXM, we defined genetic variants on rat chromosome 3 that reduced relative tumor growth and hematogenous metastasis in the SS.BN3(IL2Rγ) consomic model compared with the SS(IL2Rγ) parental strain. Paradoxically, these effects occurred despite an increase in the density of tumor-associated blood vessels. In contrast, lymphatic vasculature and lymphogenous metastasis were unaffected by the SS.BN3(IL2Rγ) background. Through comparative mapping and whole-genome sequence analysis, we narrowed candidate variants on rat chromosome 3 to six genes with a priority for future analysis. Collectively, our results establish the utility of CXM to localize genetic variants affecting the tumor microenvironment that underlie differences in breast cancer risk.

Illuminating breast cancer invasion: diverse roles for cell-cell interactions

Metastasis begins when tumors invade into surrounding tissues. In breast cancer, the study of cell interactions has provided fundamental insights into this complex process. Powerful intravital and 3D organoid culture systems have emerged that enable biologists to model the complexity of cell interactions during cancer invasion in real-time. Recent studies utilizing these techniques reveal distinct mechanisms through which multiple cancer cell and stromal cell subpopulations interact, including paracrine signaling, direct cell-cell adhesion, and remodeling of the extracellular matrix. Three cell interaction mechanisms have emerged to explain how breast tumors become invasive: epithelial-mesenchymal transition, collective invasion, and the macrophage-tumor cell feedback loop. Future work is needed to distinguish whether these mechanisms are mutually exclusive or whether they cooperate to drive metastasis.

LIMD2 is a small LIM-only protein overexpressed in metastatic lesions that regulates cell motility and tumor progression by directly binding to and activating the integrin-linked kinase

Proteins that communicate signals from the cytoskeleton to the nucleus are prime targets for effectors of metastasis as they often transduce signals regulating adhesion, motility, and invasiveness. LIM domain proteins shuttle between the cytoplasm and the nucleus, and bind to partners in both compartments, often coupling changes in gene expression to extracellular cues. In this work, we characterize LIMD2, a mechanistically undefined LIM-only protein originally found to be overexpressed in metastatic lesions but absent in the matched primary tumor. LIMD2 levels in fresh and archival tumors positively correlate with cell motility, metastatic potential, and grade, including bladder, melanoma, breast, and thyroid tumors. LIMD2 directly contributes to these cellular phenotypes as shown by overexpression, knockdown, and reconstitution experiments in cell culture models. The solution structure of LIMD2 that was determined using nuclear magnetic resonance revealed a classic LIM-domain structure that was highly related to LIM1 of PINCH1, a core component of the integrin-linked kinase-parvin-pinch complex. Structural and biochemical analyses revealed that LIMD2 bound directly to the kinase domain of integrin-linked kinase (ILK) near the active site and strongly activated ILK kinase activity. Cells that were null for ILK failed to respond to the induction of invasion by LIMD2. This strongly suggests that LIMD2 potentiates its biologic effects through direct interactions with ILK, a signal transduction pathway firmly linked to cell motility and invasion. In summary, LIMD2 is a new component of the signal transduction cascade that links integrin-mediated signaling to cell motility/metastatic behavior and may be a promising target for controlling tumor spread.

Understanding susceptibility to breast cancer metastasis: the genetic approach

Metastasis is a complex phenotype that is not discrete, is polygenic, varies in range over the entire population and follows non-Mendelian inheritance. Recent evidence indicates that inherited susceptibility affects not only the development of the primary tumor, but is also an important factor in progression and metastasis. Since metastasis accounts for the majority of breast cancer deaths, identification and understanding of the genetic modifiers of metastasis underlies success of personalized therapy. Studies from our laboratory and others have now characterized several metastasis susceptibility factors. While an important step forward, these certainly do not describe the entire metastatic phenomenon and efforts continue to expand this knowledge. Here we review the complex metastatic process and current knowledge on the genetics of breast cancer metastasis, including germline polymorphisms that have been associated with the disease.

Tumor metastasis: moving new biological insights into the clinic

As the culprit behind most cancer-related deaths, metastasis is the ultimate challenge in our effort to fight cancer as a life-threatening disease. The explosive growth of metastasis research in the past decade has yielded an unprecedented wealth of information about the tumor-intrinsic and tumor-extrinsic mechanisms that dictate metastatic behaviors, the molecular and cellular basis underlying the distinct courses of metastatic progression in different cancers and what renders metastatic cancer refractory to available therapies. However, integration of such new knowledge into an improved, metastasis-oriented oncological drug development strategy is needed to thwart the development of metastatic disease at every stage of progression.

The seed and soil hypothesis revisited: current state of knowledge of inherited genes on prognosis in breast cancer

The crucial event in the course of malignancies such as breast cancer is its metastatic spread from the primary tumor of origin to distant organs. The natural history of a tumor is determined by the expression of its genes, and in this sense, knowledge has advanced dramatically in recent decades. However, much less is known about the role that the patient plays in the behavior of a tumor. In this article, we review the evidence regarding the genetic background of the host in metastatic tumor dissemination, providing information from epidemiological studies as well as from animal models and human studies. Undoubtedly, the elucidation of possible interpersonal variability in susceptibility to developing metastases would significantly contribute to improve management of cancer patients.

Using a systems biology approach to understand and study the mechanisms of metastasis

Metastasis remains the main cause for cancer-related deaths due to the lack of effective therapy. The clonal selection model has long been thought to be the primary mechanism of metastatic progression but many different mechanisms have been hypothesized for the progression from tumorigenesis to the successful dissemination and expansion of tumor cells at the secondary site. MicroRNAs, germline polymorphisms in combination with the tumor microenvironment are few of the different pathways to explain the metastatic cascade. Technological advances for high-throughput screening of cells such as expression profiling, next generation sequencing, as well as global network analyses have advanced the studies of these mechanisms. Combined with new insights into the various mechanisms of metastasis a systems biology approach has also been shown to be useful in identifying metastasis-specific gene signatures as well as predicting disease outcome. Furthermore, the results of these studies have been relevant for identifying biomarkers for metastatic disease.

Maspin: molecular mechanisms and therapeutic implications

Maspin, a non-inhibitory member of the serine protease inhibitor superfamily, has been characterized as a tumor suppressor gene in multiple cancer types. Among the established anti-tumor effects of Maspin are the inhibition of cancer cell invasion, attachment to extracellular matrices, increased sensitivity to apoptosis, and inhibition of angiogenesis. However, while significant experimental data support the role of Maspin as a tumor suppressor, clinical data regarding the prognostic implications of Maspin expression have led to conflicting results. This highlights the need for a better understanding of the context dependencies of Maspin in normal biology and how these are perturbed in the context of cancer. In this review, we outline the regulation and roles of Maspin in normal and developmental biology while discussing novel evidence and emerging theories related to its functions in cancer. We provide insight into the immense therapeutic potential of Maspin and the challenges related to its successful clinical translation.

Extracellular vesicles - biomarkers and effectors of the cellular interactome in cancer

In multicellular organisms both health and disease are defined by patterns of communication between the constituent cells. In addition to networks of soluble mediators, cells are also programed to exchange complex messages pre-assembled as multimolecular cargo of membraneous structures known extracellular vesicles (EV). Several biogenetic pathways produce EVs with different properties, and known as exosomes, ectosomes, and apoptotic bodies. In cancer, EVs carry molecular signatures and effectors of the disease, such as mutant oncoproteins, oncogenic transcripts, microRNA, and DNA sequences. Intercellular trafficking of such EVs (oncosomes) may contribute to horizontal cellular transformation, phenotypic reprograming, and functional re-education of recipient cells, both locally and systemically. The EV-mediated, reciprocal molecular exchange also includes tumor suppressors, phosphoproteins, proteases, growth factors, and bioactive lipids, all of which participate in the functional integration of multiple cells and their collective involvement in tumor angiogenesis, inflammation, immunity, coagulopathy, mobilization of bone marrow-derived effectors, metastasis, drug resistance, or cellular stemness. In cases where the EV role is rate limiting their production and uptake may represent and unexplored anticancer therapy target. Moreover, oncosomes circulating in biofluids of cancer patients offer an unprecedented, remote, and non-invasive access to crucial molecular information about cancer cells, including their driver mutations, classifiers, molecular subtypes, therapeutic targets, and biomarkers of drug resistance. New nanotechnologies are being developed to exploit this unique biomarker platform. Indeed, embracing the notion that human cancers are defined not only by processes occurring within cancer cells, but also between them, and amidst the altered tumor and systemic microenvironment may open new diagnostic and therapeutic opportunities.

Impact of host ageing on the metastatic phenotype

Ageing impacts multiple host mechanisms involved in cancer progression. Here we show that poorly metastatic Lewis lung carcinoma (LLC) cells form less bulky metastatic deposits in aged mice (>52 weeks) relative to their young (4-6 weeks) counterparts. Serial selection of LLC cells for increased metastatic capability in either young or old mice led in both cases to exaggerated growth of pulmonary nodules after only 5 cycles of in vivo passage. The respective metastatic cellular variants established in young (Y-series) or old (O-series) mice differed in cell morphology and constitutive activity of growth factor receptors, especially phospho-PDGFRa and phospho-EPHA7. These cell lines also exhibited marked differences in their time dependent profiles of cellular impedance (CI), which reflects their physical properties, such as cell shape, adhesion and interactions with substrata. In confluent monolayer culture Y-series cell lines generated high and increasing CI values, while these values remained low and constant in the O-series of cell lines. These observations suggest that the selective pressure of the metastatic microenvironment in young versus old hosts is sufficiently different to results in the enrichment of distinct, age-related metastatic phenotypes of cancer cells. Thus, age could inform therapeutic approaches to metastatic cancers.

Trespassing cancer cells: 'fingerprinting' invasive protrusions reveals metastatic culprits

Metastatic cancer cells produce invasive membrane protrusions called invadopodia and pseudopodia, which play a central role in driving cancer cell dissemination in the body. Malignant cells use these structures to attach to and degrade extracellular matrix proteins, generate force for cell locomotion, and to penetrate the vasculature. Recent work using unique subcellular fractionation methodologies combined with spatial genomic, proteomic, and phosphoproteomic profiling has provided insight into the invadopodiome and pseudopodiome signaling networks that control the protrusion of invasive membranes. Here I highlight how these powerful spatial 'omics' approaches reveal important signatures of metastatic cancer cells and possible new therapeutic targets aimed at treating metastatic disease.

Oncogenic extracellular vesicles in brain tumor progression

The brain is a frequent site of neoplastic growth, including both primary and metastatic tumors. The clinical intractability of many brain tumors and their distinct biology are implicitly linked to the unique microenvironment of the central nervous system (CNS) and cellular interactions within. Among the most intriguing forms of cellular interactions is that mediated by membrane-derived extracellular vesicles (EVs). Their biogenesis (vesiculation) and uptake by recipient cells serves as a unique mechanism of intercellular trafficking of complex biological messages including the exchange of molecules that cannot be released through classical secretory pathways, or that are prone to extracellular degradation. Tumor cells produce EVs containing molecular effectors of several cancer-related processes such as growth, invasion, drug resistance, angiogenesis, and coagulopathy. Notably, tumor-derived EVs (oncosomes) also contain oncogenic proteins, transcripts, DNA, and microRNA (miR). Uptake of this material may change properties of the recipient cells and impact the tumor microenvironment. Examples of transformation-related molecules found in the cargo of tumor-derived EVs include the oncogenic epidermal growth factor receptor (EGFRvIII), tumor suppressors (PTEN), and oncomirs (miR-520g). It is postulated that EVs circulating in blood or cerebrospinal fluid (CSF) of brain tumor patients may be used to decipher molecular features (mutations) of the underlying malignancy, reflect responses to therapy, or molecular subtypes of primary brain tumors [e.g., glioma or medulloblastoma (MB)]. It is possible that metastases to the brain may also emit EVs with clinically relevant oncogenic signatures. Thus, EVs emerge as a novel and functionally important vehicle of intercellular communication that can mediate multiple biological effects. In addition, they provide a unique platform to develop molecular biomarkers in brain malignancies.

Pancreatogastrostomy versus pancreatojejunostomy for RECOnstruction after partial PANCreatoduodenectomy (RECOPANC): study protocol of a randomized controlled trial UTN U1111-1117-9588

Background

Pancreatoduodenectomy is one of the most complex abdominal operations, usually performed for tumors of the periampullary region and chronic pancreatitis. Leakage of pancreatic juice from the pancreatoenteric anastomosis, called postoperative pancreatic fistula, is the most prominent postoperative complication. Retrospective studies show a significant reduction of fistula rates with pancreatogastrostomy as compared to pancreatojejunostomy, the most frequently employed method of pancreatoenterostomy. Most single-center prospective trials, however, have not validated this finding. A large multicenter trial is needed for clarification.

Methods/design

RECOPANC is a prospective, randomized, controlled multicenter trial with two treatment arms, pancreatogastrostomy versus pancreatojejunostomy. The trial hypothesis is that postoperative pancreatic fistula rate is lower after pancreatogastrostomy when compared to pancreatojejunostomy. Fourteen academic centers for pancreatic surgery will participate to allocate 360 patients to the trial. The duration of the entire trial is four years including prearrangement and analyses.

Discussion

Postoperative pancreatic fistula is the main reason for clinically important postoperative morbidity after pancreatoduodenectomy. The primary goal of the chosen reconstruction technique for pancreatoenteric anastomosis is to minimize postoperative fistula rate. A randomized trial performed at multiple high-volume centers for pancreatic surgery is the best opportunity to investigate one of the most crucial issues in pancreatic surgery.

Trial registration

German Clinical Trials Register DRKS00000767 (2011/03/23), FSI 2011/05/31. Universal Trial Number U1111-1117-9588.

Breast-cancer stem cells-beyond semantics

Intratumoral heterogeneity in breast cancer is well documented. Although the mechanisms leading to this heterogeneity are not understood, a subpopulation of cancer cells, cancer stem cells (CSCs), that have some phenotypic similarities with adult tissue stem cells, has been suggested to contribute to tumour heterogeneity. It has been postulated that these CSCs are dormant, and by virtue of their low proliferative activity and ability to exclude intracellular toxins, are resistant to chemotherapy and radiation therapy. These cells were initially isolated based on the presence of markers such as CD44, CD24, and ALDH1, with further characterisation using mammosphere assay and transplantation into immunodeficient mice. The CSC hypothesis raises several theoretical and practical questions. Does cancer arise in normal mammary stem cells or do some malignant cells acquire a CSC phenotype through clonal evolution? Are CSCs in different molecular (intrinsic) subtypes of breast cancer similar, or do they have distinct properties based on the subtype? Does the CSC phenotype reflect plasticity or the dynamic nature of a few cancer cells? How do these cells acquire invasive behaviour, as they go through epithelial-to-mesenchymal transition and then revert to epithelial phenotype at sites of metastasis in response to tumour microenvironmental and metastasis site-specific cues? It is increasingly recognised that the methods and assays used for identifying CSCs have substantial limitations; does this negate the entire concept? In this Personal View, we argue that the CSC phenotype represents an aggressive clone that survives in an adverse environment through constant evolution and integration of various hallmarks of cancer. This evolution could involve acquiring mutations that permit asymmetric and symmetric division, converting the host immune attack to its own advantage, and plasticity to adapt to sites of metastasis through reversible change in adhesion molecules. We also argue that the cell-type origin of cancer could affect the rate at which CSCs develop in a tumour, with an eventual effect on disease outcome.

Detection of circulating tumor cells and tumor stem cells in patients with breast cancer by using flow cytometry: a valuable tool for diagnosis and prognosis evaluation

Circulating tumor stem cells (CTSC), a subpopulation of circulating tumor cells (CTC), may lead to recurrent diseases. The aim of this study was to detect CTC (CD45(-)EpCAM(+)) and CTSC (CD45(-)EpCAM(+)CD44(+)CD24(-)) of breast cancer (BC) patients, as well as to explore their clinical relevance. CTC and CTSC in peripheral blood (PB) of 45 female BC patients were detected by using flow cytometry (FCM). SKBR-3 cells were mixed with MNC of four healthy volunteers at different ratios in order to evaluate the sensitivity of FCM. Real-time quantitative polymerase chain reaction (QRT-PCR) was conducted and compared with FCM. The expression of EPCAM between CTC < 50 and CTC ≥ 50 groups (19.98 ± 23.93 versus 29.46 ± 29.27 × 10(-5)), and the expression of CD44 between CTSC negative and positive groups (0.85 ± 0.91 versus 0.81 ± 0.75) were statistically the same. FCM had higher specificity than QRT-PCR. Statistical differences were obtained between CTC < 50 and CTC ≥ 50 groups among different TNM stages, histology stages, estrogen receptor (ER) status and progesterone receptor (PR) status (P < 0.05). Statistical differences between CTSC negative and positive groups within different TNM stages and regional lymph node metastasis (RLNM) status (P < 0.05) were also obtained. Moreover, the percentage of CTC on CD45 negative cells (CD45(-)C) among different clinical pathology was statistically different, P = 0.000. Additionally, the percentage of CTSC on CD45(-)C with TNM stage was rising (0: 0.00 ± 0.00‰, I: 0.03 ± 0.05‰, II: 0.06 ± 0.14‰, III: 0.10 ± 0.09‰, IV: 0.29 ± 0.35‰, P = 0.034). Statistical difference in the percentage of CTSC on CD45(-)C among different RLNM status (P = 0.001) was also obtained. FCM to detect CTC and CTSC may be used to diagnose disease at early stage, to guide clinical therapy or to predict prognosis.

Organ-specific markers in circulating tumor cell screening: an early indicator of metastasis-capable malignancy

Circulating tumor cells (CTCs) represent an important biological link in the spread of primary solid tumors to the metastatic disease responsible for most cancer mortality. Their detection in the peripheral blood of patients with many different carcinomas has shown that tumor-cell dissemination can proceed at an early stage of tumor development and their presence is associated with poor clinical outcomes, particularly in metastatic disease. In this article we describe how the increasingly sensitive isolation and detailed molecular characterization of CTCs has greatly improved our understanding of metastatic proliferation. We focus on how CTC detection and knowledge of the molecular architecture of these cells can serve as biomarkers to signal metastasis-capable disseminating cells and predict therapy-specific response. This has marked clinical utility for improved selection of systemic therapies to the individual needs of a cancer patient, real-time monitoring of metastatic disease treatments and the development of new targeted therapies.

Report from the fifth National Cancer Institute Mouse Models of Human Cancers Consortium Nervous System Tumors Workshop

Cancers of the nervous system are clinically challenging tumors that present with varied histopathologies and genetic etiologies. While the prognosis for the most malignant of these tumors is essentially unchanged despite decades of basic and translational science research, the past few years have witnessed the identification of numerous targetable molecular alterations in these cancers. With the advent of advanced genomic sequencing methodologies and the development of accurate small-animal models of these nervous system cancers, we are now ideally positioned to develop personalized therapies that target the unique cellular and molecular changes that define their formation and drive their continued growth. Recently, the National Cancer Institute convened a workshop to advance our understanding of nervous system cancer mouse models and to inform clinical trials by reconsidering these neoplasms as complex biological systems characterized by heterogeneity at all levels.

Minimal residual disease and circulating tumor cells in breast cancer

Tumor cell dissemination in bone marrow or other organs is thought to represent an important step in the metastatic process. The detection of bone marrow disseminated tumor cells is associated with worse outcome in early breast cancer. Moreover, the detection of peripheral blood circulating tumor cells is an adverse prognostic factor in metastatic breast cancer, and emerging data suggest that this is also true for early disease. Beyond enumeration, the characterization of these cells has the potential to improve risk assessment, treatment selection and monitoring, and the development of novel therapeutic agents, and to advance our understanding of the biology of metastasis.

Biomarkers for breast cancer stem cells: the challenges ahead

Recent studies suggest that a subset of cancer cells with the ability for self-renewal and differentiation into different cell lineages is responsible for tumor progression, metastasis and resistance therapy. These cells, designated as tumor-initiating cells, tumor-propagating cells or cancer stem cells, are of great interest for cancer prognostication and therapeutics. Numerous cell surface and intracellular markers exhibiting cancer stem cell characteristics have been identified in breast cancer, presenting a promise to use them as biomarkers. However, there is a great need for the improvement of experimental methods to detect them in clinical samples, and validate their utility as predictors of the disease outcome, propensity for metastasis and response to treatment. In this article, we present an overview of the current status of breast cancer stem cells, with a focus on biomarkers. We also discuss the technical challenges on the road to defining breast cancer stem cells as biomarkers.

The prognostic effect of ethnicity for gastric and esophageal cancer: the population-based experience in British Columbia, Canada

Background

Gastric and esophageal cancers are among the most lethal human malignancies. Their epidemiology is geographically diverse. This study compares the survival of gastric and esophageal cancer patients among several ethnic groups including Chinese, South Asians, Iranians and Others in British Columbia (BC), Canada.

Methods

Data were obtained from the population-based BC Cancer Registry for patients diagnosed with invasive esophageal and gastric cancer between 1984 and 2006. The ethnicity of patients was estimated according to their names and categorized as Chinese, South Asian, Iranian or Other. Cox proportional hazards regression analysis was used to estimate the effect of ethnicity adjusted for patient sex and age, disease histology, tumor location, disease stage and treatment.

Results

The survival of gastric cancer patients was significantly different among ethnic groups. Chinese patients showed better survival compared to others in univariate and multivariate analysis. The survival of esophageal cancer patients was significantly different among ethnic groups when the data was analyzed by a univariate test (p = 0.029), but not in the Cox multivariate model adjusted for other patient and prognostic factors.

Conclusions

Ethnicity may represent underlying genetic factors. Such factors could influence host-tumor interactions by altering the tumor's etiology and therefore its chance of spreading. Alternatively, genetic factors may determine response to treatments. Finally, ethnicity may represent non-genetic factors that affect survival. Differences in survival by ethnicity support the importance of ethnicity as a prognostic factor, and may provide clues for the future identification of genetic or lifestyle factors that underlie these observations.

The 'chemoinvasion' assay, 25 years and still going strong: the use of reconstituted basement membranes to study cell invasion and angiogenesis

Invasive and metastatic cells must cross basement membranes (BMs) in order to disseminate to distant sites. The 'chemoinvasion assay' using a reconstituted basement membrane, matrigel, in Boyden blind-well chambers was developed 25 years ago as a tool for invasion and metastasis research. Since then, it was adapted for investigation of how different cells types engage with and penetrate basement membrane, including research in angiogenesis, invasive cell migration, protease functions, and preclinical development of anti-invasive and anti-angiogenic agents. As novel mechanisms of metastasis and angiogenesis come to light and old paradigms are challenged, we examine how the assay can still provide innovative insights. We review established applications and variants of the matrigel invasion assay, highlight key findings derived from it and discuss future developments, including roles for accessory and cancer stem cells.

Germline genetic variation, cancer outcome, and pharmacogenetics

Studies of the role of germline or inherited genetic variation on cancer outcome can fall into three distinct categories. First, the impact of highly penetrant but lowly prevalent mutations of germline DNA on cancer prognosis has been studied extensively for BRCA1 and BRCA2 mutations as well as mutations related to hereditary nonpolyposis colorectal cancer syndrome. These mainly modest-sized analyses have produced conflicting results. Although some associations have been observed, they may not be independent of other known clinical or molecular prognostic factors. Second, the impact of germline polymorphisms on cancer prognosis is a burgeoning field of research. However, a deeper understanding of potentially confounding somatic changes and larger multi-institutional, multistage studies may be needed before consistent results are seen. Third, research examining the impact of germline genetic variation on differential treatment response or toxicity (pharmacogenetics) has produced some proof-of-principle results. Putative germline pharmacogenetic predictors of outcome include DPYD polymorphisms and fluorouracil toxicity, UGT1A1 variation and irinotecan toxicity, and CYP2D6 polymorphisms and tamoxifen efficacy, with emerging data on predictors of molecularly targeted or biologic drugs. Here we review data pertaining to these germline outcome and germline toxicity relationships.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

MFSD2A is a novel lung tumor suppressor gene modulating cell cycle and matrix attachment

BACKGROUND

MFSD2A (major facilitator superfamily domain containing 2) gene maps on chromosome 1p34 within a linkage disequilibrium block containing genetic elements associated with progression of lung cancer.

RESULTS

Here we show that MFSD2A expression is strongly downregulated in non-small cell lung cancer cell lines of different histotypes and in primary lung adenocarcinomas. Experimental modulation of MFSD2A in lung cancer cells is associated with alteration of mRNA levels of genes involved in cell cycle control and interaction with the extracellular matrix. Exogenous expression of MFSD2A in lung cancer cells induced a G1 block, impaired adhesion and migration in vitro, and significantly reduced tumor colony number in vitro (4- to 27-fold, P < 0.0001) and tumor volume in vivo (approximately 3-fold, P < 0.0001). siRNA knockdown studies in normal human bronchial epithelial cells confirmed the role of MFSD2A in G1 regulation.

CONCLUSION

Together these data suggest that MFSD2A is a novel lung cancer tumor suppressor gene that regulates cell cycle progression and matrix attachment.

Differences in the expression profiles of excision repair crosscomplementation group 1, x-ray repair crosscomplementation group 1, and betaIII-tubulin between primary non-small cell lung cancer and metastatic lymph nodes and the significance in mid-term survival

INTRODUCTION

This study aimed to compare the expression profiles of excision repair crosscomplementation group 1 (ERCC1), x-ray repair crosscomplementation group 1 (XRCC1), and betaIII-tubulin between patients with primary non-small cell lung cancer (NSCLC) and those with metastatic lymph nodes and to identify the prognostic significance of each chemotherapy resistance protein.

MATERIALS

Those who met the inclusion criteria were patients (1) with NSCLC, (2) with metastatic lymph nodes (N1 or N2), and (3) who underwent surgical resection followed by platinum-based adjuvant chemotherapy. A total of 82 patients were included in the study. The expression profile of each protein was evaluated by immunohistochemistry and compared according to tumor location.

RESULTS

The mean age of the patients was 57.5 +/- 8.4 years. There were 30 N1 and 52 N2 patients. ERCC1 expression was upregulated in 55% and downregulated in 8% of metastatic lymph nodes, when compared with primary tumors (p < 0.05). XRCC1 was also upregulated in 56% and downregulated in 6% (p < 0.05). However, betaIII-tubulin was upregulated in 12% and downregulated in 45% of patients (p < 0.05). betaIII-tubulin expression in metastatic lymph nodes was greater in patients with adenocarcinoma than other cell types. Upregulation of ERCC1 in metastatic lymph nodes was a poor prognostic factor in N1 patients but not in N2 patients.

CONCLUSIONS

Significant changes in the expression profile of each protein were observed in metastatic lymph nodes. The resistance protein-guided treatment should be performed after integrative interpretation of expression profiles of each protein in both primary and metastatic sites.

Genetic disparity between primary tumours, disseminated tumour cells, and manifest metastasis

Recent genetic analyses of paired samples from primary tumours and disseminated tumour cells have uncovered a bewildering genetic disparity. It was therefore proposed that ectopically residing tumour cells disseminate early and develop independently into metastases parallel to the primary tumour. Alternatively, these cells may represent an irrelevant cell population unable to spawn metastases whereas only cells that disseminated late in primary tumour development (which therefore are similar to the primary tumour) will form manifest metastasis. Here, we review comparative analyses of paired samples from primary tumours and disseminated tumour cells or primary tumours and metastases. The data demonstrate a striking disparity, questioning the use of primary tumours as surrogate for the genetics of systemic cancer. In the era of molecular therapies that build upon genetic defects of tumour cells, these data call for a direct diagnostic pathology of systemic cancer.