MT1-MMP (MMP-14) is a multifunctional protease that regulates ECM degradation, activation of other proteases, and a variety of cellular processes, including migration and viability in physiological and pathological contexts. Both the localization and signal transduction capabilities of MT1-MMP are dependent on its cytoplasmic domain that constitutes the final 20 C-terminal amino acids, while the rest of the protease is extracellular. In this review, we summarize the ways in which the cytoplasmic tail is involved in regulating and enacting the functions of MT1-MMP. We also provide an overview of known interactors of the MT1-MMP cytoplasmic tail and the functional significance of these interactions, as well as further insight into the mechanisms of cellular adhesion and invasion that are regulated by the cytoplasmic tail.

• Keywords
• MT1-MMP, cell invasion, intracellular trafficking, matrix metalloproteinases, post-translational modifications,
• MeSH
• Cell Adhesion MeSH
• Matrix Metalloproteinase 14 * metabolism   MeSH
• Cell Movement MeSH
• Signal Transduction * MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Matrix Metalloproteinase 14 * MeSH

Cancer cell invasion through tissue barriers is the intrinsic feature of metastasis, the most life-threatening aspect of cancer. Detailed observation and analysis of cancer cell behaviour in a 3D environment is essential for a full understanding of the mechanisms of cancer cell invasion. The inherent limits of optical microscopy resolution do not allow to for in-depth observation of intracellular structures, such as invadopodia of invading cancer cells. The required resolution can be achieved using electron microscopy techniques such as FIB-SEM. However, visualising cells in a 3D matrix using FIB-SEM is challenging due to difficulties with localisation of a specific cell deep within the resin block. We have developed a new protocol based on the near-infrared branding (NIRB) procedure that extends the pattern from the surface grid deep inside the resin. This 3D burned pattern allows for precise trimming followed by targeted 3D FIB-SEM. Here we present detailed 3D CLEM results combining confocal and FIB-SEM imaging of cancer cell invadopodia that extend deep into the collagen meshwork.

• Keywords
• CLEM, FIB-SEM, MT1-MMP, invadopodia, invasiveness,
• MeSH
• Spectroscopy, Near-Infrared methods   MeSH
• Fibrosarcoma pathology   MeSH
• Neoplasm Invasiveness MeSH
• Humans MeSH
• Microscopy, Electron, Scanning methods   MeSH
• Tumor Cells, Cultured MeSH
• Breast Neoplasms pathology   MeSH
• Image Processing, Computer-Assisted MeSH
• Podosomes pathology   MeSH
• Imaging, Three-Dimensional methods   MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

The plasticity of cancer cell invasion represents substantial hindrance for effective anti-metastatic therapy. To better understand the cancer cells' plasticity, we performed complex transcriptomic and proteomic profiling of HT1080 fibrosarcoma cells undergoing mesenchymal-amoeboid transition (MAT). As amoeboid migratory phenotype can fully manifest only in 3D conditions, all experiments were performed with 3D collagen-based cultures. Two previously described approaches to induce MAT were used: doxycycline-inducible constitutively active RhoA expression and dasatinib treatment. RNA sequencing was performed with ribo-depleted total RNA. Protein samples were analysed with tandem mass tag (TMT)-based mass spectrometry. The data provide unprecedented insight into transcriptome and proteome changes accompanying MAT in true 3D conditions.

• MeSH
• Fibrosarcoma pathology   MeSH
• Neoplasm Invasiveness * MeSH
• Collagen chemistry   MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Cell Movement * MeSH
• Proteome * MeSH
• rhoA GTP-Binding Protein MeSH
• Sequence Analysis, RNA MeSH
• Tandem Mass Spectrometry MeSH
• Transcriptome * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Dataset MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Collagen MeSH
• Proteome * MeSH
• rhoA GTP-Binding Protein MeSH
• RHOA protein, human MeSH Browser

Observation and analysis of cancer cell behaviour in 3D environment is essential for full understanding of the mechanisms of cancer cell invasion. However, label-free imaging of live cells in 3D conditions is optically more challenging than in 2D. Quantitative phase imaging provided by coherence controlled holographic microscopy produces images with enhanced information compared to ordinary light microscopy and, due to inherent coherence gate effect, enables observation of live cancer cells' activity even in scattering milieu such as the 3D collagen matrix. Exploiting the dynamic phase differences method, we for the first time describe dynamics of differences in cell mass distribution in 3D migrating mesenchymal and amoeboid cancer cells, and also demonstrate that certain features are shared by both invasion modes. We found that amoeboid fibrosarcoma cells' membrane blebbing is enhanced upon constriction and is also occasionally present in mesenchymally invading cells around constricted nuclei. Further, we demonstrate that both leading protrusions and leading pseudopods of invading fibrosarcoma cells are defined by higher cell mass density. In addition, we directly document bundling of collagen fibres by protrusions of mesenchymal fibrosarcoma cells. Thus, such a non-invasive microscopy offers a novel insight into cellular events during 3D invasion.

• MeSH
• Cell Membrane metabolism   MeSH
• Cell Culture Techniques methods   MeSH
• Fibrosarcoma diagnostic imaging   pathology   MeSH
• Holography instrumentation   methods   MeSH
• Intravital Microscopy instrumentation   methods   MeSH
• Neoplasm Invasiveness diagnostic imaging   pathology   MeSH
• Collagen metabolism   MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Cell Movement * MeSH
• Pseudopodia metabolism   MeSH
• Imaging, Three-Dimensional instrumentation   methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Collagen MeSH

In solid cancers, invasion and metastasis account for more than 90% of mortality. However, in the current armory of anticancer therapies, a specific category of anti-invasion and antimetastatic drugs is missing. Here, we coin the term 'migrastatics' for drugs interfering with all modes of cancer cell invasion and metastasis, to distinguish this class from conventional cytostatic drugs, which are mainly directed against cell proliferation. We define actin polymerization and contractility as target mechanisms for migrastatics, and review candidate migrastatic drugs. Critical assessment of these antimetastatic agents is warranted, because they may define new options for the treatment of solid cancers.

• Keywords
• contractility, invasion, metastasis, migrastatics, solid cancer, treatment,
• MeSH
• Drug Resistance, Neoplasm MeSH
• Molecular Targeted Therapy MeSH
• Humans MeSH
• Neoplasm Metastasis drug therapy   MeSH
• Biomarkers, Tumor MeSH
• Neoplasms drug therapy   etiology   metabolism   pathology   MeSH
• Drug Discovery * MeSH
• Cell Movement drug effects   MeSH
• Antineoplastic Agents chemistry   pharmacology   therapeutic use   MeSH
• Signal Transduction drug effects   MeSH
• Drug Synergism MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Biomarkers, Tumor MeSH
• Antineoplastic Agents MeSH

Apico-basal polarity is typical of cells present in differentiated epithelium while front-rear polarity develops in motile cells. In cancer development, the transition from epithelial to migratory polarity may be seen as the hallmark of cancer progression to an invasive and metastatic disease. Despite the morphological and functional dissimilarity, both epithelial and migratory polarity are controlled by a common set of polarity complexes Par, Scribble and Crumbs, phosphoinositides, and small Rho GTPases Rac, Rho and Cdc42. In epithelial tissues, their mutual interplay ensures apico-basal and planar cell polarity. Accordingly, altered functions of these polarity determinants lead to disrupted cell-cell adhesions, cytoskeleton rearrangements and overall loss of epithelial homeostasis. Polarity proteins are further engaged in diverse interactions that promote the establishment of front-rear polarity, and they help cancer cells to adopt different invasion modes. Invading cancer cells can employ either the collective, mesenchymal or amoeboid invasion modes or actively switch between them and gain intermediate phenotypes. Elucidation of the role of polarity proteins during these invasion modes and the associated transitions is a necessary step towards understanding the complex problem of metastasis. In this review we summarize the current knowledge of the role of cell polarity signaling in the plasticity of cancer cell invasiveness.

• Keywords
• AMT, EMT, invasion, plasticity, polarity,
• MeSH
• Neoplasm Invasiveness pathology   MeSH
• Humans MeSH
• Neoplasms pathology   MeSH
• Cell Polarity physiology   MeSH
• Signal Transduction physiology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

The precision medicine (PM) initiative is a response to the dismal outlook in solid cancer. Despite heterogeneity, common mechanistic denominators may exist across the spectrum of solid cancer. A shift from conventional research and development (R&D) toward PM will require conceptual and structural change. As individuals and as a society, we welcome innovation, but question change. We ask: In solid cancer, does PM identify and address the causes of prior failures, and, if so, are the proposed solutions feasible? And, when may we expect safer, more effective and affordable drugs in the clinic? Considerations that prompt a pragmatic rethink include a failure analysis of translational R&D in solid cancer suggesting that trials and regulations need to be aligned with the natural history of the disease. In successful therapeutic interventions in chronic, complex disease, surrogate markers and endpoints should be consistent with the Prentice's criteria. In solid cancer, drug induced tumor shrinkage, is a drug effect and not a disease response; tumor shrinkage does not reflect nor predict interruption of the disease. Overall, we support a pragmatic, multidisciplinary, and collaborative R&D, and suggest that direction be set by clinical need and utility, and by questions, not answers. PM will prove worthwhile if it could improve clinical outcomes. The lag in therapeutics relative to diagnostics is a cause for confusion. Overdiagnosis adds to fear and harm, especially in the absence of effective interventions. A revised initiative that prioritizes metastasis research could replicate the successful HIV/AIDS model in solid cancer. A pragmatic approach may further translational efforts toward meaningfully effective, generally available, and affordable solutions.

• Keywords
• 21st Century Cures Act, Paul Ehrlich, RECIST, metastasis, pragmatism, precision medicine, solid cancer, translation,
• Publication type
• Journal Article MeSH

BACKGROUND: The local invasion of tumor cells into the surrounding tissue is the first and most critical step of the metastatic cascade. Cells can invade either collectively, or individually. Individual cancer cell invasion can occur in the mesenchymal or amoeboid mode, which are mutually interchangeable. This plasticity of individual cancer cell invasiveness may represent an escape mechanism for invading cancer cells from anti-metastatic treatment. METHODS: To identify new signaling proteins involved in the plasticity of cancer cell invasiveness, we performed proteomic analysis of the amoeboid to mesenchymal transition with A375m2 melanoma cells in a 3D Matrigel matrix. RESULTS: In this screen we identified PKCα as an important protein for the maintenance of amoeboid morphology. We found that the activation of PKCα resulted in the mesenchymal-amoeboid transition of mesenchymal K2 and MDA-MB-231 cell lines. Consistently, PKCα inhibition led to the amoeboid-mesenchymal transition of amoeboid A375m2 cells. Next, we showed that PKCα inhibition resulted in a considerable decrease in the invading abilities of all analyzed cancer cell lines. CONCLUSIONS: Our results suggest that PKCα is an important protein for maintenance of the amoeboid morphology of cancer cells, and that downregulation of PKCα results in the amoeboid to mesenchymal transition. Our data also suggest that PKCα is important for both mesenchymal and amoeboid invasiveness, making it an attractive target for anti-metastatic therapies.

• MeSH
• Neoplasm Invasiveness genetics   pathology   MeSH
• Humans MeSH
• Melanoma genetics   pathology   MeSH
• Mesoderm metabolism   pathology   MeSH
• Cell Line, Tumor MeSH
• Cell Movement genetics   MeSH
• Protein Kinase C-alpha biosynthesis   genetics   MeSH
• Proteomics MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Signal Transduction MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• PRKCA protein, human MeSH Browser
• Protein Kinase C-alpha MeSH

BACKGROUND: Although there is extensive evidence for the amoeboid invasiveness of cancer cells in vitro, much less is known about the role of amoeboid invasiveness in metastasis and the importance of Rho/ROCK/MLC signaling in this process. RESULTS: We analyzed the dependence of amoeboid invasiveness of rat and chicken sarcoma cells and the metastatic activity of chicken cells on individual elements of the Rho/ROCK/MLC pathway. In both animal models, inhibition of Rho, ROCK or MLC resulted in greatly decreased cell invasiveness in vitro, while inhibition of extracellular proteases using a broad spectrum inhibitor did not have a significant effect. The inhibition of both Rho activity and MLC phosphorylation by dominant negative mutants led to a decreased capability of chicken sarcoma cells to metastasize. Moreover, the overexpression of RhoA in non-metastatic chicken cells resulted in the rescue of both invasiveness and metastatic capability. Rho and ROCK, unlike MLC, appeared to be directly involved in the maintenance of the amoeboid phenotype, as their inhibition resulted in the amoeboid-mesenchymal transition in analyzed cell lines. CONCLUSION: Taken together, these results suggest that protease-independent invasion controlled by elements of the Rho/ROCK/MLC pathway can be frequently exploited by metastatic sarcoma cells.

• MeSH
• Neoplasm Invasiveness MeSH
• rho-Associated Kinases metabolism   MeSH
• Rats MeSH
• Chickens MeSH
• Myosin Light Chains metabolism   MeSH
• Cell Line, Tumor MeSH
• Cell Movement MeSH
• rho GTP-Binding Proteins metabolism   MeSH
• Sarcoma metabolism   pathology   MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• rho-Associated Kinases MeSH
• Myosin Light Chains MeSH
• rho GTP-Binding Proteins MeSH

Despite remarkable progress in cancer-drug discovery, the delivery of novel, safe, and sustainably effective products to the clinic has stalled. Using Src as a model, we examine key steps in drug development. The preclinical evidence on the relationship between Src and solid cancer is in sharp contrast with the modest anticancer effect noted in conventional clinical trials. Here, we consider Src inhibitors as an example of a promising drug class directed to invasion and metastasis and identify roadblocks in translation. We question the assumption that a drug-induced tumor shrinkage in preclinical and clinical studies predicts a successful outcome. Our analysis indicates that the key areas requiring attention are related, and include preclinical models (in vitro and mouse models), meaningful clinical trial end points, and an appreciation of the role of metastasis in morbidity and mortality. Current regulations do not reflect the natural history of the disease, and may be unrelated to the key complications: local invasion, metastasis, and the development of resistance. Alignment of preclinical and clinical studies and regulations based on mechanistic trial end points and platforms may help in overcoming these roadblocks. Viewed kaleidoscopically, most elements necessary and sufficient for a novel translational paradigm are in place.

• Keywords
• Src inhibitors, cancer, drug resistance, metastasis, paradigms, translation,
• Publication type
• Journal Article MeSH