Aggressive Medulloblastoma-Derived Exosomal miRNAs Promote In Vitro Invasion and Migration of Tumor Cells Via Ras/MAPK Pathway

Medulloblastomas (MBs) are currently divided into 4 molecular subgroups: WNT, SHH, Group 3, and Group 4. Among them, Group 3 MB has the worst prognosis, and 40%–50% of Group 3 cases are already metastatic at the time of diagnosis. Emerging evidence indicates that exosomes drive tumor invasion, but very little is known about exosomes in MBs. In this study, we initially discovered that exosomes isolated from Group 3 MB cell lines altered in vitro behaviors of a less invasive SHH MB cell line and yielded a much more aggressive phenotype. RNA-sequencing analysis revealed 7 exosomal miRNAs with markedly different expression levels between the SHH and Group 3 MB cell lines. They were all predicted to be related to the Ras/MAPK pathway according to the Kyoto Encyclopedia of Genes and Genomes data analysis. Increased expression of miR-181a-5p, miR-125b-5p, and let-7b-5p was further confirmed in Group 3 MB cells with real-time PCR and was shown to increase in vitro invasion and migratory abilities of tumor cells through the activation of ERK in Ras/MAPK pathway. Collectively, our findings suggest that exosomal miRNAs have a critical role in MB progression in vitro and might serve as diagnostic biomarkers and therapeutic targets.

The effect of co-treatment with DAPT and oxaliplatin on the biological behavior of human ovarian cancer stem cells

To assess the effects of the combination of DAPT and oxaliplatin on the biological behavior of human ovarian cancer stem cells. In vitro cultured human ovarian cancer stem cells were randomly divided into DAPT, L-OHP, DAPT + L-OHP, and control groups. MTT assays were measured to assess the ability of inhibit proliferation. Inverted microscopy, flow cytometry, and in vitro invasion assays were performed to assess cell morphology, apoptosis, and cell invasion, respectively. Then, western blotting was used to detect Notch-1 and LRP1 expression in the four groups of cells. MTT assay revealed that DAPT and L-OHP monotherapy could inhibit the proliferation of ovarian cancer stem cells in a time- and dose-dependent manner. Inverted microscopy showed that untreated ovarian cancer stem cells had an oval or polygonal morphology, with a plump shape and large nuclei. After treatment with DAPT or L-OHP, cells shrank and cracked, with an irregular shape and increased shedding. Flow cytometry revealed that apoptosis was significantly higher in the DAPT and L-OHP groups compared with the control group; the DAPT + L-OHP group had a significantly higher rate of apoptosis than either the DAPT or L-OHP groups. An in vitro invasion assay revealed that DAPT + L-OHP inhibited cell invasion to a greater extent than either DAPT or L-OHP alone. Western blotting revealed that, compared with control, L-OHP had no effect on Notch-1 protein expression, whereas DAPT and DAPT + L-OHP significantly reduced Notch1 protein levels. In addition, cells treated with DAPT + L-OHP expressed much less Notch than those treated with DAPT alone. In the L-OHP group, LRP protein levels were increased significantly, whereas levels were decreased significantly in the DAPT and DAPT + L-OHP groups. DAPT inhibits the proliferation of ovarian cancer stem cells, promotes their apoptosis, weakens their invasive ability, and functions synergistically with L-OHP.