We reported recently that roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, arrested human MCF-7 breast cancer cells in G2 phase of the cell cycle and concomitantly induced apoptosis. On the other hand, ROSC-induced G1 arrest observed by another group has not been accompanied by apoptosis. Therefore, we decided to prove to which extent components of tissue culture media could affect the primary action of ROSC. For this purpose we compared the efficacy of the ROSC treatment on MCF-7 cells cultivated in medium with and without phenol red. The kinetics of MCF-7 cell proliferation strongly depended on the presence of phenol red that has been recognized previously as a weak estrogen. Exposure of MCF-7 cells cultivated in phenol red-deprived medium to ROSC resulted in a strong G2 arrest and apoptosis. However, the anti-proliferative and pro-apoptotic action of ROSC was strongly diminished in cells maintained in medium containing phenol red. The ratio of the G2 cell population after 12 h ROSC was reduced by approximately 20% in the latter and correlated with the lack of CDK2 inactivation. Moreover, the kinetics of ROSC-induced apoptosis was delayed in the presence of phenol red. These results clearly evidence that the efficacy of the therapy of ER-positive breast cancers by CDK inhibitors is diminished in the presence of estrogen-mimicking compounds and indicate that phytoestrogens and xenoestrogens could interfere with the therapy. Therefore, the exposure of cancer patients to the estrogen mimics should be avoided at least during chemotherapy by CDK inhibitors.

Abstract:Estrogens play an important role in the growth and terminal differentiation of the mammary gland. Prolonged exposure to estrogens seems to predispose women to breast cancer. It recently became evident that not only the intrinsic hormonal status but also external factors such as the occurrence of pharmaceuticals and chemicals with hormone activity in the environment may put women at greater risk of developing breast cancer. We focused on the interference of endocrine disruptors in breast cancer therapy. We observed that phenol red added to the culture medium strongly promoted the cell proliferation and cell cycle progression of human cells expressing the estrogen receptor, and affected their susceptibility to chemotherapy.

On the African continent, the use of Internet and social media has been growing at an incredible speed in the past decade. Social media have thus been used in an array of instances such as election periods, natural disasters, and political crises. However, previous research on social media has barely taken a look at the use of social media during war. By investigating on the use of Twitter during the post electoral crisis in Côte d'Ivoire in 2010/2011, this study wants to emphasize the potential of social media for the development of democracy in the context of crisis, war, and limited media freedom. Through a content analysis of Twitter and qualitative expert interviews with Ivoirian bloggers, this study found that Twitter was mainly used for political debate and crowdsourcing information. The crisis turning over to a civil war, the network was used in particular by a small group of active citizens and bloggers, operating as technically versed opinion leaders, to provide humanitarian help for the population caught in the crisis. Results further showed that mobile devices played a crucial role for the use of Twitter within the country and indicated that the post electoral crisis considerably contributed to the discovery of Twitter in Côte d'Ivoire. A central finding is that Twitter, on the one hand, was used for diffusing false information and expressing verbal violence and, on the other hand, it served to verify information and throwback rumors.