Circadian and cell cycle clock systems in cancer

The circadian clock and the cell cycle are dynamic biological events. Over the last decades, our understanding of the molecular mechanisms underlying these systems has greatly improved, with extensive development and use of mathematical models. In sharp contrast, little is known about how these two crucial oscillators interact, and how these interactions affect cellular proliferation, DNA repair and apoptosis, in normal or cancer cells. On the one hand, the disruption of circadian clocks impairs cell physiology and quality of life. On the other hand, disruption of cell cycle, DNA repair or apoptosis can profoundly impact on cell and organism survival. Experimental and clinical data show that circadian disruption accelerates malignant proliferation, and that DNA damage can reset the circadian clock. Therefore, a central question to be addressed is how interactions between the circadian clock and the cell cycle affect cellular proliferation and (geno)toxic sensitivity in normal and cancer cells, and how this knowledge translates into new prevention or treatments. C5Sys integrates experimental, mathematical and bioinformatic approaches to explore the dynamic links between circadian clock and cell cycle, and their relevance for normal and malignant cell physiology and proliferation. C5Sys maps these interactions and the coupling between both oscillatory systems through a systems biology (SB) approach. C5Sys investigates how the circadian clock can act as a gatekeeper of cell cycle progression in normal and cancer cells. This will result in the identification of novel targets for these clock-cell cycle interactions, whose internal or external perturbations could affect cancer progression and/or could impact on cancer treatments. C5Sys assembles 7 European teams with extensive complementary background and wide international scientific recognition in the fields of circadian clocks, cancer dynamics, DNA repair and apoptosis, as well as bioinformatics, mathematical models and time series analysis and imaging. C5Sys is organised in 5 workpackages (WP), with tight mutual interactions between experimental, mathematical and statistical teams within and between WPs. C5Sys will: 1) map critical interaction nodes between circadian and cell cycle clocks, whose disruption is relevant for altered or malignant proliferation; 2) characterize the time scales in the signalling pathways, which are critical for the coupling of both biological clocks, including those operating at higher frequency; 3) determine the rhythmic signals whose disruption participates in malignant growth; 4) provide an integrated 'proliferative' cellular model incorporating circadian and cell cycle clocks and underlying rhythmic signalling pathways; 5) determine model properties in cancer cells; 6) probe the relevance of targeted interventions for disrupting or reinforcing the coupling of circadian clock and cell cycle in silico; and 7) attempt to provide in vitro and in vivo proof of principles of the relevance of model-based chronotherapeutic interventions. The novel cell lines, biomarker monitoring methods and mathematical tools, which will be developed as a result of this proposal, will circumvent current bottlenecks in the exploration of temporal changes in functional genomics and their potential therapeutic relevance for cancer. C5sys results will trigger 1) innovative chronotherapeutic research for several human diseases involving circadian and cell cycle systems and 2) dedicated technology development for scientific and biomedical applications.

C5Sys assembles 7 European teams with extensive complementary background and wide international scientific recognition in the fields of circadian clocks, cancer dynamics, DNA repair and apoptosis, as well as bioinformatics, mathematical models and time series analysis and imaging. C5Sys is organised with tight mutual interactions between experimental, mathematical and statistical teams within and between WPs. The 4 experimental teams and the 3 mathematical teams will work together to design model-driven experiments, with the aim of gathering the required data for model optimization, as well as offering experimental 'proofs of principle' of this highly integrated SB approach. In WP1, molecular biology, pharmacology and dynamic multi-parameter or multiscale imaging methods, are applied in vitro to cultured mouse, zebrafish and human cell lines or in vivo to laboratory fish; results from time series are used as inputs to generate models, which in turn serve to design experiments, in an iterative manner. WP3 conducts a similar in vitro, in vivo and in silico methodology, using mouse and human cancer cell lines, including tumor transplantation models. This separation of normal-proliferative (WP1) and malignant (WP3) cell types will allow, for the first time, at experimental and model comparison of clock-cell cycle interactions between these two cell types within WP2. Bioinformatic and theoretical tools, as well as experimental techniques are handled in WP4.The combination of time series analyses with discriminant and bioinformatic methods identifies core clusters in clock-controlled pathways. To probe this, WP2 performs simulations in experimentally based models and identifies their main properties. Theoretical physiopathologic or therapeutic applications are derived through WP2 and WP4 interactions and validated in WP1 and WP3. SB training will result from research visits between partners of different expertise (WP5).

Who will benefit and why. Little is known about how the circadian clock and the cell cycleinteract, and how these interactions affect cellular proliferation, DNA repair and apoptosis, in normal or cancer cells. These are key question of basic importance to a very broad range of biological and biomedical researchers. Since the disruption of circadian clocks impairs cell physiology and quality of life and is implicated in aging and cancer (e.g. WHO classified shift work as a likely cause of cancer) and because the clock controls a high proportion of genes and the clock-controlled biological processes include the sleep-wake cycle, body temperature, hormone secretion, cell proliferation, metabolism and drug detoxification. The results of our project will be of interest to both the cancer and ageing research communities including those in academia and charity research groups because (a) the disruption of circadian clocks impairs cell physiology and quality of life and is implicated in aging and cancer (e.g. WHO classified shift work as a likely cause of cancer) and because the clock controls a high proportion of genes and the clock-controlled biological processes include the sleep-wake cycle, body temperature, hormone secretion, cell proliferation, metabolism and drug detoxification; and (b) a central question to be addressed is how interactions between the circadian clock and the cell cycle affect cellular proliferation and (geno)toxic sensitivity in normal and cancer cells, and how this knowledge translates into new prevention or treatments. We will be studying how drugs can also disrupt the circadian timing system as a function of dose and circadian time of delivery and the optimal circadian delivery of anticancer drugs. In view of this the results and approach should be of interest to those involved in drug design and discovery and pharmacology and the pharmaceutical industry. Since C5Sys integrates experimental, mathematical and bioinformatic approaches to explore the dynamic links between circadian clock and cell cycle it will be of great interest to both the Systems Biology community and to mathematicians, physicists and engineers. Dissemination and communication. Workpackage 5 is dedicated to this and will produce/create: - a dedicated page within the websites of each partner for external communication; - at least either one open scientific workshop, or a symposium at an international meeting; - external access to C5Sys databases; - management of intellectual property at an international level; - a review of the intellectual property value of the outputs of the project; - dedicated meetings with all partners, to which patent office delegates will be invited, to assess the aims, milestones, and deliverables of the project and determine where the greatest potential to produce information with commercial value could occur; - a dedicated C5Sys website to be managed by WSB and the INSERM group - guidelines and recommendations regarding management and IP; - a skills database, available materials, resources, and standard operating protocols to promote networking and increase knowledge sharing; - coordinated use of communication tools of each partner/ to promote General public awareness; - open access domain for public announcement or public information/announcement; - press releases on opening and when appropriate. Within the scientific community results will be mostly disseminated through publications and/or communications to congresses or workshops. Partners will use their industrial contacts to make them aware of the C5Sys project and expected results. At present privileged contacts with pharmaceutical or biotechnological industries involve Merck-Serono (Germany), Pfizer-France, Sanofi (France), Cyclacel (UK), BBraun (France) and Hospital Services (Italy) for INSERM, and Danone (Netherlands) and Schering-Plough (Netherlands) for EMC. For further details see WP 5 and full proposal.