Ectopic expression of CC chemokine receptor 7 promotes prostate cancer cells metastasis via Notch1 signaling.

There currently exists no satisfactory treatment for patients with prostate cancer with local evolution and distant metastasis. Previous studies have confirmed the importance of CC chemokine receptor 7 (CCR7) in the invasion and metastasis of prostate cancer. And increasing evidence prove that Notch1 can play diametrically opposite roles in the development and progression of different tumors. To demonstrate the correlation between CCR7 and Notch1, PC-3 cells were transfected with pcDNA3.1-CCR7 or CCR7 si-RNA, respectively. Then Western blot analysis was used to detect the expressions of Notch1, ERK, P38, JNK, NF-κB, MMP-9, and epithelial-mesenchymal transition (EMT)-related proteins. Moreover, matrigel invasion assays were performed to assess the migratory and invasive activities of PC-3 cells. PcDNA3.1-CCR7 increased the expression of Notch1, phospho-MAPK, phospho-P65, MMP-9, N-cadherin, and Snail in PC-3 cells, but decreased the expression of E-cadherin. PcDNA3.1-CCR7 also promoted the migration and invasion of PC-3 cells. However, CCR7 si-RNA reversed the effect of pcDNA3.1-CCR7 in PC-3 cells. And MAPK and NF-κB pathway inhibitors were used to testify that activation of Notch1 induces EMT through MAPK and NF-κB pathway. All these results indicate that upregulation of Notch1 by CCR7 can accelerate the evolution of EMT and develop the invasion and metastasis in prostate cancer cells by activating MAPK and NF-κB signaling pathways in prostate cancer cells, which provides a new molecular evidence for targeted therapy in metastatic prostate cancer.

Biomechanical Heterogeneity of Living Cells: Comparison between Atomic Force Microscopy and Finite Element Simulation.

Atomic force microscopy (AFM) indentation is a popular method for characterizing the micromechanical properties of soft materials such as living cells. However, the mechanical data obtained from deep indentation measurements can be difficult and problematic to interpret as a result of the complex geometry of a cell, the nonlinearity of indentation contact, and constitutive relations of heterogeneous hyperelastic soft components. Living MDA-MB-231 cells were indented by spherical probes to obtain morphological and mechanical data that were adopted to build an accurate finite element model (FEM) for a parametric study. Initially, a 2D-axisymmetric numerical model was constructed with the main purpose of understanding the effect of geometrical and mechanical properties of constitutive parts such as the cell body, nucleus, and lamellipodium. A series of FEM deformation fields were directly compared with atomic force spectroscopy in order to resolve the mechanical convolution of heterogeneous parts and quantify Young's modulus and the geometry of nuclei. Furthermore, a 3D finite element model was constructed to investigate indentation events located far from the axisymmetric geometry. In this framework, the joint FEM/AFM approach has provided a useful methodology and a comprehensive characterization of the heterogeneous structure of living cells, emphasizing the deconvolution of geometrical structure and the true elastic modulus of the cell nucleus.

Atomic force microscopy methodology and AFMech Suite software for nanomechanics on heterogeneous soft materials.

Atomic force microscopy has proven to be a valuable technique to characterize the mechanical and morphological properties of heterogeneous soft materials such as biological specimens in liquid environment. Here we propose a 3-step method in order to investigate biological specimens where heterogeneity hinder a quantitative characterization: (1) precise AFM calibration, (2) nano-indentation in force volume mode, (3) array of finite element simulations built from AFM indentation events. We combine simulations to determine internal geometries, multi-layer material properties, and interfacial friction. In order to easily perform this analysis from raw AFM data to simulation comparison, we propose a standalone software, AFMech Suite comprising five interacting interfaces for simultaneous calibration, morphology, adhesion, mechanical, and simulation analysis. We test the methodology on soft hydrogels with hard spherical inclusions, as a soft-matter model system. Finally, we apply the method on E. coli bacteria supported on soft/hard hydrogels to prove usefulness in biological field.

MiRNALet-7a mediates prostate cancer PC-3 cell invasion, migration by inducing epithelial-mesenchymal transition through CCR7/MAPK pathway.

Prostate cancer is one of the most common malignancies in older men. Recent evidence has demonstrated microRNA (miRNA) Let-7a expression decreased in prostate cancer, while the expression of CC chemokine receptor type 7 (CCR7) increased. In this study, we investigated whether CCR7 overexpression was associated with a decrease in the expression of miRNA Let-7a in invasion and metastasis of prostate cancer cell. Synthetic Let-7a mimics and Let-7a inhibitors were transfected into prostate cancer PC-3 cells, respectively. Then Western blot was used to detect the expression of CCR7, ERK, p38, MMP-9, and Epithelial-Mesenchymal Transition (EMT)-related proteins. Matrigel invasion assays were performed to assess the migratory and invasive activities of PC3 cells. To confirm the fact that 3'UTR of CCR7 is a direct target of Let-7a, a luciferase assay for the reporter gene expressing the Let-7a binding sites of CCR7 3'UTR was used. Synthetic Let-7a mimics decreased prostate cancer cell migration and invasion, as well as the expression of CCR7, phospho-p38, phospho-ERK1/2, MMP-9, N-cadherin, and Snail in PC-3 cells. The Let-7a inhibitors reversed the effects of Let-7a on PC-3 cells. The 3'UTR of CCR7 was confirmed as a direct target of Let-7a by using the luciferase assay. All findings demonstrated that Let-7a/CCR7 axis regulated EMT progress in prostate cancer cells and mediated the tumor cell invasion and migration process via activation of P38/ERK signal pathway. Our results suggested that the therapeutic potential of Let-7a as an antitumor and antimetastatic manager in prostate cancer and CCR7 may be regarded as a therapeutic target for the prostate cancer treatment.

Investigation of micromechanical properties of hard sphere filled composite hydrogels by atomic force microscopy and finite element simulations.

Atomic force microscopy (AFM) indentation is the most suitable way to characterize micromechanical properties of soft materials such as bio tissues. However, the mechanical data obtained from force-indentation measurement are still not well understood due to complex geometry of the bio tissue, nonlinearity of indentation contact, and constitutive relation of hyperelastic soft material. Poly-N-isopropyl acrylamide (PNIPAM) filled with 5wt% polystyrene (PS) sphere particles material system can be utilized as a simplified model for mimicking a whole host of soft materials. Finite element model has been constructed to simulate indentation as in AFM experiments using colloidal probes for a parametric study, with the main purpose of understanding the effect of particles on overall behavior of mechanical data and local deformation field under indentation contact. Direct comparison between finite element simulation and indentation data from AFM experiments provides a powerful method to characterize soft materials properties quantitatively, addressing the lack of analytical solutions for hard-soft composites, both biological and synthetic ones. In this framework, quantitative relations are found between the depth, at which the particle was embedded, the particle size and the elastic modulus of the overall composite. Comprehensive characterizations were established to distinguish indentation on a particle residing on top of the hydrogel from a particle embedded inside the hydrogel matrix. Finally, different assumptions of interface friction at the boundary between the particle and the hydrogel have been tested and directly compared with experimental measurements.