Natural products are widely used as source for drugs development. An interesting example is represented by natural drugs developed against human topoisomerase IB, a ubiquitous enzyme involved in many cellular processes where several topological problems occur due the formation of supercoiled DNA. Human topoisomerase IB, involved in the solution of such problems relaxing the DNA cleaving and religating a single DNA strand, represents an important target in anticancer therapy. Several natural compounds inhibiting or poisoning this enzyme are under investigation as possible new drugs. This review summarizes the natural products that target human topoisomerase IB that may be used as the lead compounds to develop new anticancer drugs. Moreover, the natural compounds and their derivatives that are in clinical trial are also commented on.

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Moyamoya disease and syndrome constitute two distinct pathological entities with a primary finding of progressive distal internal carotid artery occlusion, which results in either an ischemic or hemorrhagic sequela. While the disease entity stands as a primary arterial vasculopathy, moyamoya syndrome represents a secondary vasculopathy associated with a systemic inflammatory process. We describe a patient with an ischemic stroke and angiographic findings of moyamoya in the setting of positive antinuclear antibodies and anti-Scl-70 antibodies with clinical features of scleroderma on exam. A review of current literature identified three similar cases where immunosuppression in addition to secondary stroke prevention led to reduced frequency of neurological sequelae. These cases plus our own demonstrate that patients with moyamoya vasculopathy in association with anti-Scl 70 antibodies exist on a spectrum with either predominant scleroderma features or neurological symptoms. There are a limited number of cases reported of moyamoya vasculopathy in association with anti-Scl 70 antibodies. This case report demonstrates that not only may the association be more common than we think, but that it exists on a dynamic spectrum with variable clinical presentation and course.

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The continuous need for the development of new small molecule anti-cancer drugs calls for easily accessible sensor systems for measuring the effect of vast numbers of new drugs on their potential cellular targets. Here we demonstrate the use of an optical DNA biosensor to unravel the inhibitory mechanism of a member of a new family of small molecule human topoisomerase I inhibitors, the so-called indeno-1,5-naphthyridines. By analysing human topoisomerase I catalysis on the biosensor in the absence or presence of added drug complemented with a few traditional assays, we demonstrate that the investigated member of the indeno-1,5-naphthyridine family inhibited human topoisomerase I activity by blocking enzyme-DNA dissociation. To our knowledge, this represents the first characterized example of a small molecule drug that inhibits a post-ligation step of catalysis. The elucidation of a completely new and rather surprising drug mechanism-of-action using an optical real time sensor highlights the value of this assay system in the search for new topoisomerase I targeting small molecule drugs.

Sarcoidosis and systemic sclerosis (SSc) rarely coexist. Here, we report a Japanese female SSc patient who developed systemic sarcoidosis. Her SSc was a limited type negative for anti-Scl-70 antibody and positive for anticentromere antibody (ACA). Moreover, we performed a review of the English-language published work that described cases of concurrent SSc and sarcoidosis. Then, we found that most SSc and sarcoidosis concurrent patients positive for anti-Scl-70 antibody were male (77.8%). On the other hand, most patients positive for ACA were female (87.5%). These results suggest some relationships between autoantibody profiles and sex in SSc and sarcoidosis concurrence.

BACKGROUND: Mutations altering BLM function are associated with highly elevated cancer susceptibility (Bloom syndrome). Thus, genetic variants of BLM and proteins that form complexes with BLM, such as TOP3A and RMI1, might affect cancer risk as well.
METHODS: In this study we have studied 26 tagged single nucleotide polymorphisms (tagSNPs) in RMI1, TOP3A, and BLM and their associations with cancer risk in acute myeloid leukemia/myelodysplatic syndromes (AML/MDS; N = 152), malignant melanoma (N = 170), and bladder cancer (N = 61). Two population-based control groups were used (N = 119 and N = 156).
RESULTS: Based on consistency in effect estimates for the three cancer forms and similar allelic frequencies of the variant alleles in the control groups, two SNPs in TOP3A (rs1563634 and rs12945597) and two SNPs in BLM (rs401549 and rs2532105) were selected for analysis in breast cancer cases (N = 200) and a control group recruited from spouses of cancer patients (N = 131). The rs12945597 in TOP3A and rs2532105 in BLM showed increased risk for breast cancer. We then combined all cases (N = 584) and controls (N = 406) respectively and found significantly increased risk for variant carriers of rs1563634 A/G (AG carriers OR = 1.7 [95%CI 1.1-2.6], AA carriers OR = 1.8 [1.2-2.8]), rs12945597 G/A (GA carriers OR = 1.5 [1.1-1.9], AA carriers OR = 1.6 [1.0-2.5]), and rs2532105 C/T (CT+TT carriers OR = 1.8 [1.4-2.5]). Gene-gene interaction analysis suggested an additive effect of carrying more than one risk allele. For the variants of TOP3A, the risk increment was more pronounced for older carriers.
CONCLUSIONS: These results further support a role of low-penetrance genes involved in BLM-associated homologous recombination for cancer risk.

The authors describe a young man suffering from systemic sclerosis who showed a dramatic progression of skin involvement after the appearance of anti-Scl70 antibody.

Genetic and environmental perturbations often result in complex transcriptional responses involving multiple genes and regulons. In order to understand the nature of a response, one has to account for the contribution of the downstream effects to the formation of a response. Such analysis can be carried out within a statistical framework in which the individual effects are independently collected and then combined within a linear model. Here, we modeled the contribution of DNA replication, supercoiling, and repair to the transcriptional response of inhibition of the Escherichia coli gyrase. By representing the gyrase inhibition as a true pleiotropic phenomenon, we were able to demonstrate that: (1) DNA replication is required for the formation of spatial transcriptional domains; (2) the transcriptional response to the gyrase inhibition is coordinated between at least two modules involved in DNA maintenance, relaxation and damage response; (3) the genes whose transcriptional response to the gyrase inhibition does not depend on the main relaxation activity of the cell can be classified on the basis of a GC excess in their upstream and coding sequences; and (4) relaxation by topoisomerase I dominates the transcriptional response, followed by the effects of replication and RecA. We functionally tested the effect of the interaction between relaxation and repair activities, and found support for the model derived from the microarray data. We conclude that modeling compound transcriptional profiles as a combination of downstream transcriptional effects allows for a more realistic, accurate, and meaningful representation of the transcriptional activity of a genome.

Systemic sclerosis (SSc) is a generalised connective tissue disorder characterised by sclerotic changes in the skin and internal organs. The occurrence of SSc in childhood is rare, with childhood-onset disease representing 3% of all SSc cases, and fewer than 100 such patients have been reported in the world literature to date [1]. We report a case of juvenile SSc with disease onset at the age of 6 months. To our knowledge, this case is the youngest in the world literature.