Earlier findings from different cancer entities such as chro

Earlier findings from different cancer entities such as chronic myeloid leukemia (Yang et al., 2011), B cell chronic lymphocytic leukemia (Jantus Lewintre et al., 2009), prostate cancer (Zhu et al., 2009), epithelial ovarian cancer (Tokunaga et al., 2008), and colon cancer (Mazzoccoli et al., 2016, Huisman et al., 2016) indicate a reduced CRY1 glycogen synthase kinase 3 and associated this, as well as a deregulation in Bmal1 or Per2 expression (Huisman et al., 2016), to be a negative prognostic marker. Vice versa, HIFs are frequently found to be enriched in the hypoxic areas of solid tumors (Talks et al., 2000, Zhong et al., 1998). By showing that CRY1 deficiency induces HIF levels (Figures 10 and S6) and accelerates proliferation and migration, two key aspects relevant to carcinogenesis, and that knocking out HIFs either by CRISPR/Cas9 or by the use of shRNAs reversed these effects, our study now provides a mechanistic link between the above-mentioned genetic association studies. Although these findings underline the connection between CRY1 and HIFs, it appears that other regulators involved in carcinogenesis can also be regulated by CRY1. For example, several findings from both Per and Cry knockout mice strongly suggest that their dysfunction cooperates with loss of p53 during carcinogenesis (Fu and Kettner, 2013). This is also in agreement with studies showing the complex interconnections between the individual components of the circadian clock with nucleotide excision repair and DNA damage in mice (Kang and Sancar, 2009, Kang et al., 2009) which affect not only carcinogenesis but also aging.
Methods All methods can be found in the accompanying Transparent Methods supplemental file.
Acknowledgments This work was supported by grants from the Finnish Academy of Science (SA 296027), Jane and Aatos Erkko Foundation, the Finnish Cancer Foundation, the Finnish Center of International Mobility (CIMO), Biocenter Oulu, and University of Oulu to T.K.
Cancer is the second leading cause of death worldwide after cardiovascular disease. The World Health Organization estimates that cancer will account for approximately 9.6 million deaths globally in 2018, and its incidence is steadily increasing. The major treatments for cancer are surgery, radiation, and chemotherapy., However, traditional chemotherapeutic agents have a number of critical drawbacks, including harmful side-effects, non-specific biodistribution, short circulation times, and poor solubility, which result in poor therapeutic efficiency., Thus, there is a tremendous need to develop new compounds for the prevention and treatment of cancer. Hypoxia is a common feature of many solid tumors and is generally caused by the rapid proliferation of tumor cells, which leads to formation of solid masses and obstruction and compression of the blood vessels surrounding them. Hypoxia-inducible factor 1α (HIF-1α) is a transcription factor that regulates the expression of numerous genes involved in nutrient uptake, cell survival, angiogenesis, invasion, and metastasis, and thus plays an important role in cancer development., , In addition to hypoxia, exposure to certain hormones, cytokines, and growth factors can also upregulate HIF-1α expression. Consequently, HIF-1α has gained attention as a potential target for the development of anti-cancer agents. Inhibition of the HIF-1α pathway may be a particularly useful therapy for specific types of cancers, especially those commonly associated with hypoxia., Due to the importance of HIF-1α in tumor development and progression, a considerable amount of effort has been made to identify HIF-1α inhibitors for treatment of cancer., , , Ursolic acid (UA) is a pentacyclic triterpenoid found in most plant species, and it is known to possess a number of bioactive properties such as anti-inflammatory, anti-microbial, anti-oxidant, immunomodulatory, and anti-cancer activities. Indeed, Japanese researchers have ranked UA as one of the most promising potential therapeutic compounds for tumor prevention. Over the past decade, many attempts have been made to develop bioactive UA derivatives that more potently inhibit cancer cell growth. These studies have indicated that the configuration at C-3 is a critical factor for the anti-proliferative activity of UA, whereas a free hydroxyl at C-3 decreases its anti-cancer activity. Lin et al showed that incorporation of an isopropyl ester at C-28 significantly improves the anti-proliferative activity of UA, whereas introduction of a methyl at the same position together with an amino moiety at C-3 significantly enhanced its activity against HeLa cells (A). In contrast, Dar et al showed that incorporation of various substituted benzene rings at the C-2 position and retention of the carboxyl group at C-28 in UA (B) also improved its anti-cancer activity, as reflected by induction of cell cycle arrest in G1 and apoptosis of HCT-116 cells.