In this work, we constructed a Collagen I-Matrigel composite extracellular matrix (ECM). The composite ECM was used to determine the influence of the local collagen fiber orientation on the collective intravasation ability of tumor cells. We found that the local fiber alignment enhanced cell-ECM interactions. Specifically, metastatic MDA-MB-231 breast cancer cells followed the local fiber alignment direction during the intravasation into rigid Matrigel (∼10 mg/mL protein concentration).M etastasis is a lethal milestone in cancer: Cells escape from the confinement of primary tumor sites (intravasation), invade tissues as well as the lymphatic and vascular systems, and finally colonize (extravasation) distant sites. It has been estimated that less than 1% of tumor cells undergo this process, but metastasis contributes to more than 90% of cancerrelated deaths (1, 2). Metastasis involves both genetic and epigenetic alternation of tumor cells, as well as external biochemical and biophysical microenvironments (3-5). Pathology studies suggest that metastatic tumor cells exhibit highly branched morphologies and distinct aligned registration with aligned extracellular matrix (ECM) during metastatic tumor progression (4, 5).We address three important questions concerning metastasis. (i) Can we build in vitro complex ECM structures with heterogeneously oriented collagen fibers and basement membrane components to mimic the cancer cell intravasation process? (ii) How does aligned collagen influence cell intravasation into/ through the basement membrane before entering vessels? (iii) After cell detachment from the primary tumor site, how does a heterogeneous ECM with a varying degree of local fiber alignment influence cell intravasation and subsequent penetration into the basement membrane during their intravasation process? The major obstacle to addressing these questions is the difficulty in constructing both an in vitro 3D microenvironment to mimic the above process and flexible controls of the environmental parameters, such as fiber orientations in a complex collagen/Matrigel composite, nutrition, oxygen, drug concentrations, etc.In breast cancer metastasis, cancer cells are believed to reorganize and progress through the interstitial ECM matrix, break through the basement membrane, and enter blood vessels or lymphatic capillaries (6-10). Fig. 1C presents a schematic illustration of the intravasation process in metastasis. Tumor-associated collagen signatures (TACS), basically environmentally elevated collagen density and collagen fiber reorganization, are used to stage mammary carcinoma tumor progression levels (6, 11-13). Fig. 1 presents hematoxylin/eosin (H&E)-stained biopsy slices of breast cancer imaged by second harmonic generation (SHG) under a two-photon confocal microscopy (A1R MP; Nikon) (detailed information provided in SI Appendix, SI Text) (6, 14, 15). Fig. 1 A, 1-3 shows the stained human invasive ductal carcinoma tumor at grade I. In the enlarged figures (Fig. 1 A, 2 and 3), the cells have well-defined bord...

Cortical inhibitory circuits play important roles in shaping sensory processing. In auditory cortex, however, functional properties of genetically identified inhibitory neurons are poorly characterized. By two-photon imaging-guided recordings, we specifically targeted 2 major types of cortical inhibitory neuron, parvalbumin (PV) and somatostatin (SOM) expressing neurons, in superficial layers of mouse auditory cortex. We found that PV cells exhibited broader tonal receptive fields with lower intensity thresholds and stronger tone-evoked spike responses compared with SOM neurons. The latter exhibited similar frequency selectivity as excitatory neurons. The broader/weaker frequency tuning of PV neurons was attributed to a broader range of synaptic inputs and stronger subthreshold responses elicited, which resulted in a higher efficiency in the conversion of input to output. In addition, onsets of both the input and spike responses of SOM neurons were significantly delayed compared with PV and excitatory cells. Our results suggest that PV and SOM neurons engage in auditory cortical circuits in different manners: while PV neurons may provide broadly tuned feedforward inhibition for a rapid control of ascending inputs to excitatory neurons, the delayed and more selective inhibition from SOM neurons may provide a specific modulation of feedback inputs on their distal dendrites.

The level of microRNA-205 (miR-205) is commonly deregulated in a number of cancers. Through the screening of the microRNA expression profile in bladder cancer tissue and cell lines, we found that expression of miR-205 was significantly suppressed. In addition, the levels of miR-205 expression had a negative correlation with the degree of bladder cancer malignancy. However, the biological functions of miR-205 remained unclear. In this study, we have demonstrated that miR-205 had a role in the inhibition of proliferation, migration and invasion of bladder cancer cells. Moreover, we have identified cyclin J (CCNJ) gene, which is involved in cell cycle regulation, as a novel target for miR-205. Furthermore, a long non-coding RNA HOTAIR (HOX transcript antisense RNA) was observed to participate in the silencing of miR-205 in bladder cancer cells by breaking the balance of histone modification between H3K4me3 (histone H3 at lysine 4 methylation) and H3K27me3 on miR-205 promoter. This study elucidates an important role that miR-205 had in the regulation of proliferation, migration and invasion of bladder cancer cells, suggesting a potential therapeutic target for combating bladder cancer.