CircRNA_0044556 affects the sensitivity of triple-negative breast cancer cells to paclitaxel by regulating miR-665.

CircRNAs have been implicated in the development of resistance in triple-negative breast cancer (TNBC). However, the association between circRNA_0044556 and paclitaxel (PTX) resistance in TNBC is still limited. Therefore, the purpose of this study was to investigate the effect of circRNA_0044556 on biological function and PTX resistance in TNBC cells. PTX-resistant TNBC cells (MDA-MB-231/PTX) were obtained by continuously exposing MDA-MB-231 cells to increasing paclitaxel levels. The expression levels of circRNA_0044556 and miR-665 were measured by qRT-PCR. The regulatory relationship between miR-665 and circRNA_0044556 was verified by biological information website analysis and double-luciferase reporter gene detection experiments. MTT assay, clone assay, flow cytometry and Western blot analysis were used to evaluate the influence of cell biological function. Elevated circRNA_0044556 was observed in TNBC, and paclitaxel increased the expression of circRNA_0044556 in TNBC cells. In TNBC, circRNA_0044556 acted as a ceRNA for miR-665. In addition, low expression of circRNA_0044556 combined with miR-665 inhibited the proliferation of TNBC cells and paclitaxel-resistant TNBC cells while inducing cell death. Our study demonstrated that the downregulation of circRNA_0044556 inhibits the malignant progression of TNBC cells and paclitaxel resistance via miR-665. Thus, circRNA_0044556 may be a potential therapeutic target for PTX-resistance TNBC.

Temperature-mediated diffusion of nanoparticles in semidilute polymer solutions.

The temperature is often a critical factor affecting the diffusion of nanoparticles in complex physiological media, but its specific effects are still to be fully understood. Here, we constructed a temperature-regulated model of semidilute polymer solution and experimentally investigated the temperature-mediated diffusion of nanoparticles using the particle tracking method. By examining the ensemble-averaged mean square displacements (MSDs), we found that the MSD grows gradually as the temperature increases while the transition time from sublinear to linear stage in MSD decreases. Meanwhile, the temperature-dependent measured diffusivity of the nanoparticles shows an exponential growth. We revealed that these temperature-mediated changes are determined by the composite effect of the macroscale property of polymer solution and the microscale dynamics of polymer chain as well as nanoparticles. Furthermore, the measured non-Gaussian displacement probability distributions were found to exhibit non-Gaussian fat tails, and the tailed distribution is enhanced as the temperature increases. The non-Gaussianity was calculated and found to vary in the same trend with the tailed distribution, suggesting the occurrence of hopping events. This temperature-mediated non-Gaussian feature validates the recent theory of thermally induced activated hopping. Our results highlight the temperature-mediated changes in diffusive transport of nanoparticles in polymer solutions and may provide the possible strategy to improve drug delivery in physiological media.

[Biological characteristics of CD55(hig); side population in breast cancer cell line MCF-7].

AIM: To determine whether the CD55(hig); expression (CD55(hig);) cells in side population (SP) of the cell line MCF-7 possess characteristics of cancer stem cells. METHODS: Breast cancer cell line MCF-7 was cultured and the nucleic acid dye Hoechst33342 and Verapami were added. Flow cytometry (FCM) was employed to isolate the cells of SP and mian population (MP), the cells were then labeled with CD55 mAb; mean values of fluorescence intensity of CD55 in SP and MP cells were measured. CD55 mAb was used to mark the unsorted MCF-7 cells, the proportion of CD55(hig); cells was determined, and then CD55(hig); cells were sorted and collected, to observe biological characteristics, such as cell morphology, adherence rate, colony formation and cell cycle distribution as well as nude mice implantation. RESULTS: Mean value of fluorescence intensity of CD55 in SP cells was 100.85±4.57, and mean value of fluorescence intensity of CD55 in MP cells was 50.51±4.75; the proportion of CD55(hig); cell in MCF-7 cells was 2.12%; adherent rate of CD55(hig); cells in 24 h was lower than that in CD55(low); cells and 24 h after inoculation adherent rates of both cells had no significant difference (P>0.05); CD55(hig); cells were mostly spherical and kept in a suspended state at 12 hours after inoculation and culture; CD55(hig); cells had the ability of colony formation, the clone-forming rate of CD55(hig); cells was (20.04±1.07)% when the cells were cultured for one week, it was lower than the rate of (27.14±1.07)% in CD55(low); cells (P<0.01); the ratio of G0/G1 resting cells in CD55(hig); cells was (85.4±3.37)% which was higher than that in CD55(low); cells (58.6±2.55)% and in MCF-7 cells (70.73±4.21)%, which had a statistically significant difference (P<0.05). All nude mice implanted with CD55(hig); cells developed the tumor, and the pathological examination of the transplanted tumor had the properties of malignant cells. CONCLUSION: A few CD55(hig); cells were found in breast cancer MCF-7 cells, and most of CD55(hig); cells were quiescent, non-adherent as well as being in a suspended state and being hereditary after cloning, so CD55(hig); cells had biological characteristics of cancer stem cells.