In this early phase of the new era of molecularly targeted patient friendly cancer chemotherapy, there is a need for novel viable anticancer molecular targets. The MDM2 oncoprotein has been validated as a potential target for cancer drug development. MDM2 amplification and/or overexpression occur in a wide variety of human cancers, several of which can be treated experimentally with MDM2 antagonists. MDM2 interacts primarily with the p53 tumor suppressor protein in an autoregulatory negative feedback loop to attenuate p53's cell cycle arrest and apoptosis functions. Inhibition of the p53-MDM2 interaction has been shown to cause selective cancer cell death, as well as sensitize cancer cells to chemotherapy or radiation effects. Consequently, this interaction has been the main focus of anticancer drug discovery targeted to MDM2. The promotion of the proteasomal degradation of the p53 protein by MDM2 is central to its repression of the tumor suppressor functions of p53, and many proteins impinge upon this activity, either enhancing or inhibiting it. MDM2 also has oncogenic activity independent of its interaction with p53, but this has so far not been explored for drug discovery. Among the approaches for targeting MDM2 for cancer therapy, small molecule antagonists have recently featured as effective anticancer agents in experimental models, although the repertoire is currently limited and none has yet entered human clinical trials. Small molecules that have been reported to disrupt the p53-MDM2 binding, thereby enhancing p53 activity to elicit anticancer effects include the following: synthetic chalcones, norbornane derivatives, cis-imidazoline derivatives (Nutlins), a pyrazolidinedione sulfonamide and 1,4-benzodiazepine-2,5-diones, as well as tryptophan derivatives. In addition to compounds disrupting p53pMDM2 binding, three compounds have been discovered that are effective in inhibiting the E3 ligase activity of MDM2 towards p53, and should serve as leads for drug discovery targeting this aspect of the p53-MDM2 interaction as well. These compounds were discovered from library screening and/or structure-based rational drug design strategies.

Mevalonate (MVA) metabolism provides the isoprenoids used in archaeal lipid biosynthesis. In synthesis of isopentenyl diphosphate, the classical MVA pathway involves decarboxylation of mevalonate diphosphate, while an alternate pathway has been proposed to involve decarboxylation of mevalonate monophosphate. To identify the enzymes responsible for metabolism of mevalonate 5-phosphate to isopentenyl diphosphate in Haloferax volcanii, two open reading frames (HVO_2762 and HVO_1412) were selected for expression and characterization. Characterization of these proteins indicated that one enzyme is an isopentenyl phosphate kinase that forms isopentenyl diphosphate (in a reaction analogous to that of Methanococcus jannaschii MJ0044). The second enzyme exhibits a decarboxylase activity that has never been directly attributed to this protein or any homologous protein. It catalyzes the synthesis of isopentenyl phosphate from mevalonate monophosphate, a reaction that has been proposed but never demonstrated by direct experimental proof, which is provided in this account. This enzyme, phosphomevalonate decarboxylase (PMD), exhibits strong inhibition by 6-fluoromevalonate monophosphate but negligible inhibition by 6-fluoromevalonate diphosphate (a potent inhibitor of the classical mevalonate pathway), reinforcing its selectivity for monophosphorylated ligands. Inhibition by the fluorinated analog also suggests that the PMD utilizes a reaction mechanism similar to that demonstrated for the classical MVA pathway decarboxylase. These observations represent the first experimental demonstration in H. volcanii of both the phosphomevalonate decarboxylase and isopentenyl phosphate kinase reactions that are required for an alternate mevalonate pathway in an archaeon. These results also represent, to our knowledge, the first identification and characterization of any phosphomevalonate decarboxylase.

The need to obtain crop varieties that are tolerant to heat and drought cannot be overemphasised especially with the threat of climate change to agricultural productivity in sub-Saharan Africa. Bambara groundnut has been identified as a drought tolerant crop; however, variations exist among landraces with respect to drought tolerance. An experiment was therefore conducted to evaluate the performance of five bambara groundnut landraces: Black eye, Burkina, NAV 4, NAV Red and Tom, to drought and heat stress, at the Irrigation Company of Upper East Region (ICOUR) at Tono-Navrongo in the Upper East Region of Ghana. The experiment was arranged in a Randomized Complete Block Design with three replicates. The heat trial was irrigated once weekly to field capacity until crop maturity. The drought trial was irrigated once weekly until 30 DAS, after which irrigation ceased. Burkina, a landrace from Burkina Faso produced the highest pod yield of 1.2 t/ha under the heat treatment. Tom did not produce any pod yield. Under drought, Burkina exhibited the greatest root dry weight and leaf area at 120 DAS, and had the longest leaf area duration (LAD). Burkina exhibited bunch canopy architecture, while NAV 4, NAV Red, and Black eye had an intermediate canopy type and Tom a spreading type. Burkina proved the most drought and heat tolerant among the five landraces evaluated. Though a drought tolerant crop, temperatures beyond 38°C and low relative humidity can negatively affect pod yield of bambara groundnut even when irrigation is provided. It is important to test the performance of a crop under a new environment before money is invested into its production in that environment.

p53, one of the most commonly mutated genes in human cancers, is thought to be associated with cancer development. Hence, screening and identifying natural or synthetic compounds with anti-cancer activity via p53-independent pathway is one of the most challenging tasks for scientists in this field. Compound JKA97 (methoxy-1-styryl-9H-pyrid-[3,4-b]-indole) is a small molecule synthetic anti-cancer agent, with unknown mechanism(s). In this study we have demonstrated that the anticancer activity of JKA97 is associated with apoptotic induction via p53-independent mechanisms. We found that co-incubation of human colon cancer HCT116 cells with JKA97 inhibited HCT116 cell anchorage-independent growth in vitro and tumorigenicity in nude mice and also induced a cell apoptotic response, both in the cell culture model and in a tumorigenesis nude mouse model. Further studies showed that JKA97-induced apoptosis was dramatically impaired in Bax knock-out (Bax ؊/؊ ) HCT116 cells, whereas the knock-out of p53 or PUMA did not show any inhibitory effects. The p53-independent apoptotic induction by JKA97 was confirmed in other colon cancer and hepatocarcinoma cell lines. In addition, our results showed an induction of Bax translocation and cytochrome c release from the mitochondria to the cytosol in HCT116 cells, demonstrating that the compound induces apoptosis through a Bax-initiated mitochondria-dependent pathway. These studies provide a molecular basis for the therapeutic application of JKA97 against human cancers with p53 mutations.The p53 protein is a transcription factor that enhances the transcriptional expression of several genes involved in the response to genotoxic agents, such as ionizing radiation and certain chemicals, including chemical therapeutic drugs (1). After activation, p53 enables the initiation of cell cycle arrest and DNA damage repair; but when cells harbor irreparable DNA damage, p53 activates cell death programs, and the cells then undergo apoptosis (2). Our recent studies have demonstrated that p53 has a suppressive activity on the cell signaling pathways leading to the activation of AP-1 and NFB when the cell responds to UV radiation (3). We have also found that the inhibition of AP-1 and NFB by tumor suppressor p53 is mediated via up-regulation of PTEN (phosphotase and tensin homolog) expression (3). Thus, p53 is a key tumor suppressor against cancer development. However, inactivation of p53 occurs very frequently in various cancers (4). Previous studies have shown that ϳ50% of human tumors carry inactivating p53 mutations (5, 6).Cancers of the colon and rectum continue to be the third most common fatal cancers in the United States. They account for 10% of the total cancer deaths among men and women (7). The p53 tumor suppressor pathway is disrupted in most colorectal cancers (8), which is associated with tumor progression. Because conventional treatments such as radiation therapy and chemotherapy are mostly dependent on p53-mediated apoptosis (9, 10), the clinical application of those therapeutic ap...

On page 8628, an error has been detected in Fig. 3B (lower left panel, HCT116ϩJKA97). The corrected Fig. 3B On page 34760, we described the characterization of heterozygous T-DNA insertion lines (Fig. 4, B-D). Unfortunately, we have found that some of the presented results are invalid. To screen seedlings for heterozygous plants to be used for complementation, we ordered new primers because the old ones were no longer available. With these new primers, we found homozygous plants in both lines. The reason for this is a wrong annotation for the line Garlic861 (Syngenta), which, according to the new annotation, does not contain an insertion in At4g23430. Regarding the second line (117H08 from GABI-Kat), we realized that an unfortunate design of oligonucleotides was the reason why the wildtype gene was amplified in every plant that was analyzed. Because the new primers bind to different regions in the gene, this mistake was only now revealed.We conclude that Tic32 is and remains a member of the chloroplast inner envelope membrane translocase family; however, the gene At4g23430 is not essential in Arabidopsis. We regret if this error has been misleading to others working in the field. ADDITIONS AND CORRECTIONS This paper is available online at www.jbc.orgWe suggest that subscribers photocopy these corrections and insert the photocopies in the original publication at the location of the original article. Authors are urged to introduce these corrections into any reprints they distribute. Secondary (abstract) services are urged to carry notice of these corrections as prominently as they carried the original abstracts.

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Objective There is an urgent need drugs against particularly difficult to treat solid tumors such as pancreatic, triple negative breast, lung, colon, metastatic prostate cancers and melanoma. Thus, the objective of this study was to synthesize compounds based computational modeling that indicated the pyrido[3,4-b]indole class bind to MDM2, a new cancer target for which there are still no drug on the market. Methods Compounds were synthesized by established methods and tested for antiproliferative activity against a broad range of human cancer cell lines, comprising HCT116 colon, HPAC, MIA PaCa-2 and Panc-1 pancreatic, MCF-7 and MDA-MB-468 breast, A375 and WM164 melanoma, A549 lung, and LNCaP, DU145 and PC3 prostate cancer lines. Computational docking was also undertaken. Results The novel pyrido[3,4-b]indoles synthesized exhibited a clear SAR with regards to antiproliferative activity, with potent broad-spectrum anticancer activity with IC50s down to 80, 130, 130 and 200 nM for breast, colon, melanoma and pancreatic cancer cells, respectively. 1-Naphthyl at C1 combined with methoxy at C6 provided the best antiproliferative activity. Thus, compound 11 (1-naphthyl-6-methoxy-9H-pyrido[3,4-b]indole) showed the highest potency. A mechanistic feature of the compounds as a group is a strongly selective G2/M cell cycle phase arrest. Docking at on MDM2 suggested a hydrogen bond interaction between the 6-methoxy Tyr106, hydrophobic interaction with Val93, pi-pi stacking interactions with Tyr100 and His96 and hydrophobic interactions with Leu54 and Ile99. An N9-methyl group disrupted binding interactions, such as H-bond interactions involving the N9 hydrogen. Conclusion We have identified a novel series of pyrido[3,4-b]indoles with potent broad spectrum anticancer activity towards the most aggressive and difficult to treat cancers including metastatic pancreatic cancer, non-small cell lung cancer, triple negative breast cancers, and BRAFV600E mutant melanoma, as well as metastatic colon and prostate cancers. There was also evidence of selectivity towards cancer cells relative to normal cells. These compounds will serve as new leads from which novel therapeutics and molecular tools can be developed for a wide variety of cancers.

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