Invadopodia-mediated ECM degradation is enhanced in the G1 phase of the cell cycle.

The process of tumor cell invasion and metastasis includes assembly of invadopodia, protrusions capable of degrading the extracellular matrix (ECM). The effect of cell cycle progression on invadopodia has not been elucidated. In this study, by using invadopodia and cell cycle fluorescent markers, we show in 2D and 3D cultures, as well as in vivo, that breast carcinoma cells assemble invadopodia and invade into the surrounding ECM preferentially during the G1 phase. The expression (MT1-MMP, also known as MMP14, and cortactin) and localization (Tks5; also known as SH3PXD2A) of invadopodia components are elevated in G1 phase, and cells synchronized in G1 phase exhibit significantly higher ECM degradation compared to the cells synchronized in S phase. The cyclin-dependent kinase inhibitor (CKI) p27kip1 (also known as CDKN1B) localizes to the sites of invadopodia assembly. Overexpression and stable knockdown of p27kip1 lead to contrasting effects on invadopodia turnover and ECM degradation. Taken together, these findings suggest that expression of invadopodia components, as well as invadopodia function, are linked to cell cycle progression, and that invadopodia are controlled by cell cycle regulators. Our results caution that this coordination between invasion and cell cycle must be considered when designing effective chemotherapies.

Construction of scaffolds composed of acellular cardiac extracellular matrix for myocardial tissue engineering.

High rates of mortality and morbidity stemming from cardiovascular diseases unveil extreme limitations in current therapies despite enormous advances in medical and pharmaceutical sciences. Following myocardial infarction (MI), parts of myocardium undergo irreversible remodeling and is substituted by a scar tissue which eventually leads to heart failure (HF). To address this issue, cardiac patches have been utilized to initiate myocardial regeneration. In this study, a porous cardiac patch is fabricated using a mixture of decellularized myocardium extracellular matrix (ECM) and chitosan (CS). Results of rheological measurements, SEM, biodegradation test, and MTT assay showed that the scaffold composed of 3.5% (w/w) CS and 0.5% ECM has the best potential in providing cardiac progenitor cells (CPCs) with a suitable microenvironmental condition for both attachment and growth. This study demonstrates that the fabricated scaffold is capable of transmitting both mechanical and chemical cues that is native to myocardial tissue and supports efficient growth of the CPCs.

Intravital Imaging of Tumor Cell Motility in the Tumor Microenvironment Context.

Cancer cell motility and invasion are key features of metastatic tumors. Both are highly linked to tumor microenvironmental parameters, such as collagen architecture or macrophage density. However, due to the genetic, epigenetic and microenvironmental heterogeneities, only a small portion of tumor cells in the primary tumor are motile and furthermore, only a small portion of those will metastasize. This creates a challenge in predicting metastatic fate of single cells based on the phenotype they exhibit in the primary tumor. To overcome this challenge, tumor cell subpopulations need to be monitored at several timescales, mapping their phenotype in primary tumor as well as their potential homing to the secondary tumor site. Additionally, to address the spatial heterogeneity of the tumor microenvironment and how it relates to tumor cell phenotypes, large numbers of images need to be obtained from the same tumor. Finally, as the microenvironment complexity results in nonlinear relationships between tumor cell phenotype and its surroundings, advanced statistical models are required to interpret the imaging data. Toward improving our understanding of the relationship between cancer cell motility, the tumor microenvironment context and successful metastasis, we have developed several intravital approaches for continuous and longitudinal imaging, as well as data classification via support vector machine (SVM) algorithm. We also describe methods that extend the capabilities of intravital imaging by postsacrificial microscopy of the lung as well as correlative immunofluorescence in the primary tumor.