Molecular Basis Of Metastasis Research Articles

Metastasis and MAPK Pathways.

Cancer is a leading cause of death worldwide. In many cases, the treatment of the disease is limited due to the metastasis of cells to distant locations of the body through the blood and lymphatic drainage. Most of the anticancer therapeutic options focus mainly on the inhibition of tumor cell growth or the induction of cell death, and do not consider the molecular basis of metastasis. The aim of this work is to provide a comprehensive review focusing on cancer metastasis and the mitogen-activated protein kinase (MAPK) pathway (ERK/JNK/P38 signaling) as a crucial modulator of this process.

Epigenetic Deregulation of Protocadherin PCDHGC3 in Pheochromocytomas/Paragangliomas Associated With SDHB Mutations.

SDHB mutations are found in an increasing number of neoplasms, most notably in paragangliomas and pheochromocytomas (PPGLs). SDHB-PPGLs are slow-growing tumors, but ∼50% of them may develop metastasis. The molecular basis of metastasis in these tumors is a long-standing and unresolved problem. Thus, a better understanding of the biology of metastasis is needed. This study aimed to identify gene methylation changes relevant for metastatic SDHB-PPGLs. We performed genome-wide profiling of DNA methylation in diverse clinical and genetic PPGL subtypes, and validated protocadherin γ-C3 (PCDHGC3) gene promoter methylation in metastatic SDHB-PPGLs. We define an epigenetic landscape specific for metastatic SDHB-PPGLs. DNA methylation levels were found significantly higher in metastatic SDHB-PPGLs than in SDHB-PPGLs without metastases. One such change included long-range de novo methylation of the PCDHA, PCDHB, and PCDHG gene clusters. High levels of PCDHGC3 promoter methylation were validated in primary metastatic SDHB-PPGLs, it was found amplified in the corresponding metastases, and it was significantly correlated with PCDHGC3 reduced expression. Interestingly, this epigenetic alteration could be detected in primary tumors that developed metastasis several years later. We also show that PCDHGC3 down regulation engages metastasis-initiating capabilities by promoting cell proliferation, migration, and invasion. Our data provide a map of the DNA methylome episignature specific to an SDHB-mutated cancer and establish PCDHGC3 as a putative suppressor gene and a potential biomarker to identify patients with SDHB-mutated cancer at high risk of metastasis who might benefit from future targeted therapies.

Abstract A01: Mechanical properties of matrices strongly influence spontaneous tumor dormancy and responses to chemotherapy in a 3D model of metastasis

Abstract Background: Distant metastasis is the major cause of breast cancer (BrCa)-related mortality with half of the disseminated disease emerging clinically after 5 or more years of seeming “cure” of the primary tumor. The lack of relevant accessible model systems for metastasis has hindered our understanding of the molecular basis of metastasis and the development of therapies against these lethal outgrowths. Furthermore, standard culture techniques employ rigid surfaces that are associated with driving even non-transformed cells towards aggressive phenotypes. To address this gap, we previously developed an innovative all-human 3D ex vivo hepatic microphysiological system (MPS) that faithfully reproduces human liver physiology. This MPS also enables spontaneous dormancy in subpopulations of, but not all, BrCa cells. In this study, we query this subpopulation effect by examining matrix stiffness on the occurrence of spontaneous tumor dormancy; we compared a conventional polystyrene material (~3 GPa) to a PEG-based hydrogel biomaterial (~100 kPa) that more closely approaches the malleable physiologic consistency of the liver (~600 Pa). We hypothesized that providing a more physiological environment would promote BrCa dormancy and provide increased protection from chemotherapy as observed in patients, enabling the study of this elusive but critical stage in cancer progression. Methods: A hepatic all-human MPS was retrofitted with hydrogel scaffolding in place of the standard polystyrene. Hydrogel scaffolds were formed by micromolding with polydimethylsiloxane (PDMS) and UV-initiated free radical polymerization. Prior to polymerization, a SynKRGD peptide sequence was conjugated to PEGDa via Michael-type addition to aid in hepatocyte interaction with the hydrogel. The MPS incorporated de-identified excess primary human hepatocytes and non-parenchymal cells (NPCs) isolated from therapeutic patient liver resections. MDA-MB-231 BrCa cells (RFP labeled) were seeded on day 3 and allowed time to intercalate into the hepatic tissue prior to treatment with chemotherapies on day 7 for 72 h. Proliferation was determined by RFP quantification, Ki67 staining and EdU incorporation. Hepatic tissue function was monitored by protein catabolism (urea), metabolism (glucose, CYP P450) and injury markers (AST, ALT). Multiplex bead-based immunoassays of 77 analytes were used to assess physiologic tissue health, cancer markers and inflammatory signals as well as to discern signaling networks within the metastatic niche. Results: The use of hydrogels in this system further fostered spontaneous BrCa quiescent dormancy, as indicated by a lower presence of BrCa cells and decreased proliferation. Hepatic tissue in hydrogel scaffolds secreted lower levels of pro-inflammatory analytes and NPCs were more responsive to inflammatory stimuli. As a result, high dose chemotherapy that targets proliferating cells was less effective against BrCa cells within tissues supported by hydrogel scaffolds. Interestingly, proliferation (emergence) of BrCa cells was observed following treatment with the lower doses of chemotherapy. The lower doses may be damaging the hepatic tissue, causing cellular stress and activation of the more responsive NPCs, which in turn secrete signals that promote the outgrowth and emergence of BrCa cells. Conclusion: These data suggest that using hydrogel scaffolds to more closely align the physiologic and mechanical properties of the macro-environment imparts a healthier hepatic microenvironment. This allowed for interesting insights into the effect of different chemotherapeutic doses on dormant BrCa cells, and highlights this all-human hepatic model of metastasis fitted with hydrogel scaffolds as a critical tool in the assessment and development of therapeutic strategies to target dormant metastatic BrCa. Citation Format: Amanda M. Clark, Sarah E. Wheeler, Carissa L. Young, Jaclyn Shepard Neiman, Venkateswaran Pillai, Linda Stockdale, Donna Stolz, Douglas A. Lauffenburger, Raman Venkataramanan, Linda G. Griffith, Alan Wells. Mechanical properties of matrices strongly influence spontaneous tumor dormancy and responses to chemotherapy in a 3D model of metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A01.

The molecular signature of breast cancer metastasis to bone.

Distant metastasis during the advanced stage of malignant tumor progression can cause considerable morbidity in cancer patients. Bone is known to be one of the most common sites of distant metastasis in patients with breast cancer (BC). BC metastases in bone are associated with excessive skeletal complications. These complications can be fatal and reduce quality of life of patients. It is important to understand the metastatic process of BC to bone to improve quality of life and design new therapeutic methods. At present, the molecular mechanisms leading to the BC metastasis to bone are not fully understood. Studying the molecular basis of BC metastasis to bone might improve our insight into this complex process. In addition, it can provide novel approaches for designing advanced and effective targeted therapies. The present article aimed to review the published papers on the molecular basis of the metastatic process of BC to bone, focusing on involved genes and signaling networks. Furthermore, we propose potential therapeutic targets that may be more effective for the inhibition and treatment of BC metastasis to bone.

MiR-136 suppresses tumor invasion and metastasis by targeting RASAL2 in triple-negative breast cancer.

MicroRNAs play an important role in the regulation of cancer migration, invasion and metastasis. Patients with triple-negative breast cancer (TNBC) have a high incidence of early relapse and metastasis; however, the molecular basis for metastasis and recurrence in these individuals remains largely unknown. Herein, we demonstrate that miR-136 is an anti-invasive microRNA in TNBC and suppresses mesenchymal invasion and metastasis. Our results demonstrated that miR-136 was downregulated in TNBC and negative correlated with the WHO grades. However, RASAL2 was identified as a functional target of miR-136, and was overexpressed in TNBC and correlates with pathological grades. Moreover, overexpression of RASAL2 in a breast cancer cell line rescued miR-136-mediated cell migration and invasion. In conclusion, these results indicate that the miR-136/RASAL2/MET axis act as a suppressor of TNBC metastasis.

Abstract PR11: Elucidating candidate biomarkers of breast cancer progression and dormancy using a 3D model of metastasis

Abstract Distant metastasis is the major cause of breast cancer (BrCa)-related mortality with half of the disseminated disease emerging clinically after 5 or more years of seeming “cure” of the primary tumor. The lack of relevant accessible model systems for metastases has hindered our understanding of the molecular basis of metastasis, the development of therapies, and the elucidation of biomarkers to detect these lethal outgrowths in real time. To address this gap, we developed an innovative all-human 3D ex vivo hepatic microphysiological system (MPS), which faithfully reproduces human physiology and effectively recreates spontaneous quiescence in a population of BrCa cells. Thus facilitating the investigation of BrCa behavior in a micrometastatic niche. The MPS incorporated primary human hepatocytes and non-parenchymal cells (NPC) isolated from patient liver resections. BrCa cells (RFP+) were seeded on day 3 and allowed time to intercalate into the hepatic tissue before treatment with chemotherapies (such as doxorubicin) on day 7 for 72h. Surviving BrCa cells were stimulated on day 13 with physiological inflammatory stressors (LPS/EGF) and cultured through day 15. Proliferation was determined by RFP quantification, Ki67 staining and EdU incorporation. Physiological functioning of hepatic tissue was monitored at multiple time points by protein catabolism (urea), active nutrient metabolism (glucose, CYP P450) and injury markers (AST, ALT). Luminex assays (57 analytes) were used to identify potential metastatic BrCa biomarkers in the hepatic milieu during different stages, both dormancy and progression, and determine communication networks within the micrometastatic niche. Spontaneous dormancy was observed amongst a subpopulation of BrCa cells (Ki67-/EdU-) after 12 days of culture. Following chemotherapy, the surviving BrCa cells were non-proliferating, quiescent (Ki67-/EdU-). Furthermore, re-emergence of the surviving non-proliferating cancer cells was then observed in the presence of physiological inflammatory stressors. Preliminary high-content analyses of secreted cytokines and growth factors identified candidate biomarkers of metastatic BrCa in hepatic tissue. Elevations in 11 soluble signaling factors in effluent from untreated proliferating BrCa were detected, of which actively growing cells were specifically associated with HGF, MCP-1, MIP-1β, RANTES (> 2-fold) compared to hepatic tissue alone and dormant BrCa effluent. Candidate biomarkers of dormancy were also identified when dormant cultures were compared to both hepatic tissue alone and proliferating BrCa cultures, 5 soluble signaling factors (HB-EGF, IL-18, VEGF-A, IL-10, IL-12p70). Further analyses found altered soluble signaling factors due to the presence of NPCs during attenuation and progression of BrCa, indicating NPCs within the hepatic microenvironment are implicated in regulating the dormant micrometastatic niche. This MPS provides unprecedented insights into the tumor cell biology of growing and dormant micrometastases. First, it mimics the dormancy and outgrowth observed in patients - i.e. dormant breast cancer cells resistant to chemotherapy could be stimulated to re-emerge following an inflammatory insult. Second, this system provides an accessible tool enabling the identification of candidate biomarkers of BrCa progression and dormancy within the micrometastatic niche; significantly, the latter aspect of dormant biomarkers is exceedingly novel. Ultimately, these collective innovative capabilities are instrumental in the development of therapeutic strategies to target dormant metastatic BrCa. Citation Format: Amanda M. Clark, Sarah E. Wheeler, Carissa L. Young, Venkateswaran C. Pillai, Donna B. Stolz, Douglas A. Lauffenburger, Raman Venkataramanan, Linda G. Griffith, Alan Wells. Elucidating candidate biomarkers of breast cancer progression and dormancy using a 3D model of metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr PR11.

Metastasis review: from bench to bedside

Cancer is the final result of uninhibited cell growth that involves an enormous group of associated diseases. One major aspect of cancer is when cells attack adjacent components of the body and spread to other organs, named metastasis, which is the major cause of cancer-related mortality. In developing this process, metastatic cells must successfully negotiate a series of complex steps, including dissociation, invasion, intravasation, extravasation, and dormancy regulated by various signaling pathways. In this review, we will focus on the recent studies and collect a comprehensive encyclopedia in molecular basis of metastasis, and then we will discuss some new potential therapeutics which target the metastasis pathways. Understanding the new aspects on molecular mechanisms and signaling pathways controlling tumor cell metastasis is critical for the development of therapeutic strategies for cancer patients that would be valuable for researchers in both fields of molecular and clinical oncology.

Functional genomic analysis of cancer metastasis: biologic insights and clinical implications

Metastasis, the spread of cancer from primary tumors to distant vital organs, has devastating consequences. Lack of effective tools to study this complex problem has hindered the development of accurate prognostic methods and effective treatments for metastatic cancer. In the postgenomic era, the application of genomic profiling methods to the analysis of clinical metastasis samples and animal metastasis models has revolutionized the field of metastasis research. This article reviews recent breakthroughs in the functional genomic analysis of metastasis. In addition, its impacts on our understanding of the molecular basis of metastasis and on clinical practice are discussed.

A phosphatase associated with metastasis of colorectal cancer.

To gain insights into the molecular basis for metastasis, we compared the global gene expression profile of metastatic colorectal cancer with that of primary cancers, benign colorectal tumors, and normal colorectal epithelium. Among the genes identified, the PRL-3 protein tyrosine phosphatase gene was of particular interest. It was expressed at high levels in each of 18 cancer metastases studied but at lower levels in nonmetastatic tumors and normal colorectal epithelium. In 3 of 12 metastases examined, multiple copies of the PRL-3 gene were found within a small amplicon located at chromosome 8q24.3. These data suggest that the PRL-3 gene is important for colorectal cancer metastasis and provide a new therapeutic target for these intractable lesions.

Intravital videomicroscopy of the chorioallantoic microcirculation: A model system for studying metastasis

The chick embryo is a useful model for studying hematogenous metastasis. Cancer cells injected into veins of the chorioallantoic membrane (CAM) circulate briefly through all tissues but form metastases predominantly in the CAM. This respiratory organ is particularly suitable for intravital microscope because of its accessibility without the need for surgery and the density and planar configuration of its vessels (which we confirmed by microcorrosion casting). Using an inverted microscope with oblique transillumination for high-resolution images and epifluorescence to identify labeled B16F1 melanoma cells, we studied successive stages of metastasis formation in the CAM in vivo. By 2 min postinjection (pi) all cancer cells had become arrested within the microvasculature. This initial arrest appeared to be due to size restriction, based on measurements of cell and vessel diameters. At 15–60 min pi, trapped cells were seen in tapering arterioles (27%), orifices from arterioles to the capillary plexus (61%), or in the plexus itself (12%). Some cells had extravasated into the underlying mesenchyme by 3 hr (pi), and at 24 hr all cancer cells had completed this process. The mean rate of migration out of capillary lumens was ∼1 μm/hr. Micrometastases grew in a planar configuration just beneath the capillary plexus, with a cell doubling time of ∼24 hr. Our technique is also applicable to other tumor types and host animals and provides a powerful tool to complement studies on the molecular basis of metastasis.