Spontaneous RhoA activity at membrane protrusions is spatially associated with closure, but not formation of inter-endothelial gaps, whereas RhoA activity at distant contractile filaments contributes to thrombin-induced disruption of junctional integrity. Thus, these data indicate that distinct RhoA activities are associated with disruption and re-annealing of endothelial junctions.

Oncolytic adenoviruses represent a novel class of anticancer agents. Their efficacy in killing cancer cells is variable, suggesting that there is room for improvement. Host miRNAs have been shown to play important roles in susceptibility of cells to replication of different viruses. This study investigated if adenovirus replication in human prostate cancer cells is influenced by host cell miRNA expression. To this end, human miRNA expression in response to adenovirus infection was analyzed, and functional screens for lytic adenovirus replication were performed using synthetic miRNA mimic and inhibitor libraries. Adenovirus infection generally reduced miRNA expression. On top of this nonspecific interference with miRNA biogenesis, a set of miRNAs, including in particular miR-222, was found specifically reduced. Another set of miRNAs was found to promote adenovirus-induced death of prostate cancer cells. In most cases, this did not stimulate adenovirus propagation. The exception was miR-26b. Overexpression of miR-26b inhibited adenovirus-induced NF-κB activation, augmented adenovirus-mediated cell death, increased adenovirus progeny release, and promoted adenovirus propagation and spread in several human prostate cancer cell lines. This suggests that miR-26b is particularly useful to be combined with oncolytic adenovirus for more effective treatment of prostate cancer.

Lung cancer is the most common cancer worldwide and on top of that has a very poor prognosis, which is reflected by a 5-year survival rate of 5% to 15%. Radiotherapy is an integral part of most treatment regimens for this type of tumor, often combined with radiosensitizing cytotoxic drugs. In this study, we identified many genes that could potentially be exploited for targeted radiosensitization using a genome-wide siRNA screen in non-small cell lung cancer (NSCLC) cells. The screen identified 433 siRNAs that potentially sensitize lung cancer cells to radiation. Validation experiments showed that knockdown of expression of Forkhead box M1 (FOXM1) or microtubuleassociated serine/threonine kinase-like (MASTL) indeed causes radiosensitization in a panel of NSCLC cells. Strikingly, this effect was not observed in primary human fibroblasts, suggesting that the observed radiosensitization is specific for cancer cells. Phosphoproteomics analyses with and without irradiation showed that a number of cell-cycle-related proteins were significantly less phosphorylated after MASTL knockdown in comparison to the control, while there were no changes in the levels of phosphorylation of DNA damage response proteins. Subsequent analyses showed that MASTL knockdown cells respond differently to radiation, with a significantly shortened G 2 -M phase arrest and defects in cytokinesis, which are followed by a cell-cycle arrest. In summary, we have identified many potential therapeutic targets that could be used for radiosensitization of NSCLC cells, with MASTL being a very promising and druggable target to combine with radiotherapy.

Deoxycytidine kinase (dCK) is essential for phosphorylation of natural deoxynucleosides and analogs, such as gemcitabine and cytarabine, two widely used anticancer compounds. Regulation of dCK is complex, including Ser-74 phosphorylation. We hypothesized that dCK could be regulated by two additional mechanisms: micro-RNA (miRNA) and promoter methylation. Methylation-specific PCR (MSP) revealed methylation of the 3' GC box in three out of six cancer cell lines. The 3' GC box is located at the dCK promoter region. The methylation status was related to dCK mRNA expression. TargetScan and miRanda prediction algorithms revealed several possible miRNAs targeting dCK and identified miR-330 (micro-RNA 330) as the one conserved between the human, the chimpanzee, and the rhesus monkey genomes. Expression of miR-330 in various colon and lung cancer cell lines, as measured by QRT-PCR, varied five-fold between samples and correlated with in-vitro gemcitabine resistance (R = 0.82, p = 0.04). Exposure to gemcitabine also appeared to influence miR-330 levels in these cell lines. Furthermore, in our cell line panel, miR-330 expression negatively correlated with dCK mRNA expression (R = 0.74), suggesting a role of miR-330 in post-transcriptional regulation of dCK. In conclusion, the 3' GC box and miR-330 may regulate dCK expression in cancer cells.

The centrosome plays a key role in cancer invasion and metastasis. However, it is unclear how abnormal centrosome numbers are regulated when prostate cancer (PCa) cells become metastatic. CP110 was previously described for its contribution of centrosome amplification (CA) and early development of aggressive cell behaviour. However its regulation in metastatic cells remains unclear. Here we identified miR-129-3p as a novel metastatic microRNA. CP110 was identified as its target protein. In PCa cells that have metastatic capacity, CP110 expression was repressed by miR-129-3p. High miR-129-3p expression levels increased cell invasion, while increasing CP110 levels decreased cell invasion. Overexpression of CP110 in metastatic PCa cells resulted in a decrease in the number of metastasis. In tissues of PCa patients, low CP110 and high miR-129-3p expression levels correlated with metastasis, but not with the expression of genes related to EMT. Furthermore, overexpression of CP110 in metastatic PCa cells resulted in excessive-CA (E-CA), and a change in F-actin distribution which is in agreement with their reduced metastatic capacity. Our data demonstrate that miR-129-3p functions as a CA gatekeeper in metastatic PCa cells by maintaining pro-metastatic centrosome amplification (CA) and preventing anti-metastatic E-CA.