http://www.mdpi.com/journal/marinedrugs/special_issues/antitumour-agents/ Dear Colleagues, The recent introduction to the clinic of trabectedin (Et-743) as a treatment for soft tissue sarcoma highlights the potential of marine drugs as novel antitumour agents. There is a huge and largely untapped array of small molecules in the depths of the ocean, produced by novel organisms that are only now being discovered. Other compounds that have captured the imagination include the dolastatins, bryostatins, kahalalides, didemnins, halchondrins, lamellarins and thiocaroline. The structurally diversity among this compounds is immense, from cyclic and linear peptides to products of the polyketide and alkaloid biosyntehsis pathways. There are diterpenes, pyrrole alkaloids, depsipeptides, macrolides and steroids. The targets for these natural products show a similar array of diversity, from tubulin inhibitors to other protein targets such as caspases and cyclin dependent kinases. The isolation and identification of new marine natural products with antitumour activity with be a key feature of this special issue of Marine Drugs. However, as with all natural products, these compounds were not produced in nature to act as antitumour agents, and while it may seem arrogant to suggest that we can improve on nature, this is where total synthesis and studies of structure activity relationships come into their own. The total synthesis of new natural products is clearly still of great important in the elucidation and confirmation of structure and absolute stereochemistry. But it also can contribute to our understanding of the mechanism of action of the natural product as an antitumour agent and can contribute to the design of analogues with enhanced activity. The second focus of this special issue of Marine Drugs will be on the synthesis and study of the mode of action of antitumour agents derived from the Sea. Dr. Mark Searcey Guest Editor {snippet name="submission_info"} http://www.mdpi.com/1660-3397/8/10/2702/ Cancer is considered as one of the deadliest diseases in the medical field. Apart from the preventive therapies, it is important to find a curative measure which holds no loopholes and acts accurately and precisely to curb cancer. Over the past few decades, there have been advances in this field and there are many antitumor compounds available on the market, which are of natural as well as synthetic origin. Marine chemotherapy is well recognized nowadays and profound development has been achieved by researchers to deal with different molecular pathways of tumors. However, the marine environment has been less explored for the production of safe and novel antitumor compounds. The reason is a number of shortfalls in this field. Though ample reviews cover the importance and applications of various anticancerous compounds from marine natural products, in the present review, we have tried to bring the current status of antitumor research based on marine inhibitors of cancer signaling pathways. In addition, focus has been placed on the shortfalls and probable strategies in the arena of marine antitumor drug discovery. http://www.mdpi.com/1660-3397/8/10/2702/ Fri, 15 Oct 2010 00:00:00 CEST Marine Drugs 2010-10-15 8 10 Review 2702 2720 1660-3397 Marine Antitumor Drugs: Status, Shortfalls and Strategies 2010-10-15 doi: 10.3390/md8102702 Ira Bhatnagar Se-Kwon Kim http://www.mdpi.com/1660-3397/8/10/2659/ The potential of marine benthic cyanobacteria as a source of anticancer drug candidates was assessed in a screen for induction of cell death (apoptosis) in acute myeloid leukemia (AML) cells. Of the 41 marine cyanobacterial strains screened, more than half contained cell death-inducing activity. Several strains contained activity against AML cells, but not against non-malignant cells like hepatocytes and cardiomyoblasts. The apoptotic cell death induced by the various strains could be distinguished by the role of caspase activation and sensitivity to the recently detected chemotherapy-resistance-associated prosurvival protein LEDGF/p75. One strain (M44) was particularly promising since its activity counteracted the protective effect of LEDGF/p75 overexpressed in AML cells, acted synergistically with the anthracycline anticancer drug daunorubicin in AML cells, and protected cardiomyoblasts against the toxic effect of anthracyclines. We conclude that culturable benthic marine cyanobacteria from temperate environments provide a promising and hitherto underexploited source for novel antileukemic drugs. http://www.mdpi.com/1660-3397/8/10/2659/ Thu, 14 Oct 2010 00:00:00 CEST Marine Drugs 2010-10-14 8 10 Article 2659 2672 1660-3397 Marine Benthic Cyanobacteria Contain Apoptosis-Inducing Activity Synergizing with Daunorubicin to Kill Leukemia Cells, but not Cardiomyocytes 2010-10-14 doi: 10.3390/md8102659 Linn Oftedal Frode Selheim Matti Wahlsten Kaarina Sivonen Stein Ove Døskeland Lars Herfindal http://www.mdpi.com/1660-3397/8/7/2129/ Marine natural products and their synthetic derivatives represent a major source of novel candidate anti-cancer compounds. We have recently tested the anti-cancer activity of more than forty novel compounds based on an iminoquinone makaluvamine scaffold, and have found that many of the compounds exert potent cytotoxic activity against human cancer cell lines. One of the most potent compounds, BA-TPQ [(11,12),7-(benzylamino)-1,3,4,8-tetrahydropyrrolo[4,3,2-de]quinolin-8(1H)-one], was active against a variety of human cancer cell lines, and inhibited the growth of breast and prostate xenograft tumors in mice. However, there was some toxicity noted in the mice following administration of the compound. In order to further the development of BA-TPQ, and in a search for potential sites of accumulation that might underlie the observed toxicity of the compound, we accomplished preclinical pharmacological studies of the compound. We herein report the in vitro and in vivo pharmacological properties of BA-TPQ, including its stability in plasma, plasma protein binding, metabolism by S9 enzymes, and plasma and tissue distribution. We believe these studies will be useful for further investigations, and may be useful for other investigators examining the use of similar compounds for cancer therapy. http://www.mdpi.com/1660-3397/8/7/2129/ Tue, 13 Jul 2010 00:00:00 CEST Marine Drugs 2010-07-13 8 7 Article 2129 2141 1660-3397 Preclinical Pharmacology of BA-TPQ, a Novel Synthetic Iminoquinone Anticancer Agent 2010-07-13 doi: 10.3390/md8072129 Ezell Li Xu Zhang Gurpinar Zhang Rayburn Sommers Yang Velu Wang Zhang