Knockdown of RAC1 and VASP gene expression inhibits breast cancer cell migration.

The ability of tumor cells to migrate is biologically fundamental for tumorigenesis, growth, metastasis and invasion. The present study examined the role of Ras-related C3 botulinum toxin substrate (RAC1) and vasodilator-stimulated phosphoprotein (VASP) in breast cancer cell migration. According to data in Kaplan, Oncomine and The Cancer Genome Atlas, increased expression levels of RAC1 and VASP in breast cancer are associated with decreased cancer cell differentiation, advanced pathological stage and more aggressive tumor subtypes, while increased VASP mRNA expression levels are positively correlated with a poor prognosis in patients with breast cancer. The short hairpin (sh)RNA technique was employed to knock down the expression of RAC1 or VASP. Stable interference with the expression of RAC1 or VASP using RAC1-shRNA or VASP-shRNA, respectively, was established in MCF-7 breast cancer cells. In RAC1-shRNA or VASP-shRNA cells, the protein expression levels of RAC1 or VASP were significantly downregulated compared with control cells. The proliferation and migration rates of the RAC1-shRNA or VASP-shRNA cells were significantly lower compared with control cells. It was observed that the protein expression levels of VASP also decreased in RAC1-shRNA cells compared with control cells. The results revealed that RAC1 and VASP may serve important roles in promoting the migration of MCF-7 breast cancer cells, and that VASP may among the downstream signaling molecules associated with RAC1.

The effects of celecoxib on the proliferation and ultrastructural changes of MDA-MB-231 breast cancer cells.

This study sought to investigate the effects of celecoxib on the proliferation and morphological changes of triple-negative breast cancer (TNBC) MDA-MB-231 cells. In this study, after MDA-MB-231 cells were treated with a certain concentration of celecoxib, a cell counting kit-8 (CCK-8) proliferation assay was used to detect cell viability. Western blotting was utilized to analyze the expression level of caspase-3, which is an apoptosis-related protein. In addition, the morphological changes in the cells and nuclei were determined with fluorescence and electron microscope. Apoptotic nuclei and obvious cytoplasmic vacuolization were observed with a microscope. Collectively, celecoxib can inhibit the proliferation of MDA-MB-231 cells by increasing caspase-3 expression and causing ultrastructural changes.

Betulinic acid induces apoptosis and ultrastructural changes in MDA-MB-231 breast cancer cells.

The aim of this study is to investigate the effects of betulinic acid (BA) on triple-negative breast cancer MDA-MB-231 cells and observe the ultrastructural changes. The concentration of BA required to induce apoptosis in MDA-MB-231 cells has been previously reported. In this study, a cell counting kit-8 proliferation assay was used to measure cell viability and the apoptosis rate. Western blotting was performed to observe the protein expression levels of Bcl-2. Cell morphology and changes in cell density were observed by microscopy. Electron microscopy revealed pyknotic nuclei as well as vacuoles. Collectively, our results showed the morphological mechanisms by which BA impairs the ultrastructure of MDA-MB-231 cells.

Motor patterns of the small intestine explained by phase-amplitude coupling of two pacemaker activities: the critical importance of propagation velocity.

Phase-amplitude coupling of two pacemaker activities of the small intestine, the omnipresent slow wave activity generated by interstitial cells of Cajal of the myenteric plexus (ICC-MP) and the stimulus-dependent rhythmic transient depolarizations generated by ICC of the deep muscular plexus (ICC-DMP), was recently hypothesized to underlie the orchestration of the segmentation motor pattern. The aim of the present study was to increase our understanding of phase-amplitude coupling through modeling. In particular the importance of propagation velocity of the ICC-DMP component was investigated. The outcome of the modeling was compared with motor patterns recorded from the rat or mouse intestine from which propagation velocities within the different patterns were measured. The results show that the classical segmentation motor pattern occurs when the ICC-DMP component has a low propagation velocity (<0.05 cm/s). When the ICC-DMP component has a propagation velocity in the same order of magnitude as that of the slow wave activity (∼1 cm/s), cluster type propulsive activity occurs which is in fact the dominant propulsive activity of the intestine. Hence, the only difference between the generation of propagating cluster contractions and the Cannon-type segmentation motor pattern is the propagation velocity of the low-frequency component, the rhythmic transient depolarizations originating from the ICC-DMP. Importantly, the proposed mechanism explains why both motor patterns have distinct rhythmic waxing and waning of the amplitude of contractions. The hypothesis is brought forward that the velocity is modulated by neural regulation of gap junction conductance within the ICC-DMP network.