On Nietzsche’s Concept of ‘European Nihilism’

<div><p>Aplog-1 is a simplified analog of the tumor-promoting aplysiatoxin with anti-proliferative and cytotoxic activities against several cancer cell lines. Our recent findings have suggested that protein kinase Cδ (PKCδ) could be one of the target proteins of aplog-1. In this study, we synthesized amide-aplog-1 (<b>3</b>), in which the C-1 ester group was replaced with an amide group, to improve chemical stability <i>in vivo</i>. Unfortunately, <b>3</b> exhibited seventy-fold weaker binding affinity to the C1B domain of PKCδ than that of aplog-1, and negligible anti-proliferative and cytotoxic activities even at 10⁻⁴ M. A conformational analysis and density functional theory calculations indicated that the stable conformation of <b>3</b> differed from that of aplog-1. Since 27-methyl and 27-methoxy derivatives (<b>1</b>, <b>2</b>) without the ability to bind to PKC isozymes exhibited marked anti-proliferative and cytotoxic activities at 10⁻⁴ M, <b>3</b> may be an inactive control to identify the target proteins of aplogs.</p></div

CAXII Is a Sero-Diagnostic Marker for Lung Cancer

To develop sero-diagnostic markers for lung cancer, we generated monoclonal antibodies using pulmonary adenocarcinoma (AD)-derived A549 cells as antigens by employing the random immunization method. Hybridoma supernatants were immunohistochemically screened for antibodies with AMeX-fixed and paraffin-embedded A549 cell preparations. Positive clones were monocloned twice through limiting dilutions. From the obtained monoclonal antibodies, we selected an antibody designated as KU-Lu-5 which showed intense membrane staining of A549 cells. Based on immunoprecipitation and MADLI TOF/TOF-MS analysis, this antibody was recognized as carbonic anhydrase XII (CAXII). To evaluate the utility of this antibody as a sero-diagnostic marker for lung cancer, we performed dot blot analysis with a training set consisting of sera from 70 lung cancer patients and 30 healthy controls. The CAXII expression levels were significantly higher in lung cancer patients than in healthy controls in the training set (P<0.0001), and the area under the curve of ROC was 0.794, with 70.0% specificity and 82.9% sensitivity. In lung cancers, expression levels of CAXII were significantly higher in patients with squamous cell carcinoma (SCC) than with AD (P = 0.035). Furthermore, CAXII was significantly higher in well- and moderately differentiated SCCs than in poorly differentiated ones (P = 0.027). To further confirm the utility of serum CAXII levels as a sero-diagnostic marker, an additional set consisting of sera from 26 lung cancer patients and 30 healthy controls was also investigated by dot blot analysis as a validation study. Serum CAXII levels were also significantly higher in lung cancer patients than in healthy controls in the validation set (P = 0.030). Thus, the serum CAXII levels should be applicable markers discriminating lung cancer patients from healthy controls. To our knowledge, this is the first report providing evidence that CAXII may be a novel sero-diagnostic marker for lung cancer

Synthesis and biological activities of simplified analogs of the natural PKC ligands, bryostatin-1 and aplysiatoxin.

Protein kinase C (PKC) isozymes play central roles in signal transduction on the cell surface and could serve as promising therapeutic targets of intractable diseases like cancer, Alzheimer's disease, and acquired immunodeficiency syndrome (AIDS). Although natural PKC ligands like phorbol esters, ingenol esters, and teleocidins have the potential to become therapeutic leads, most of them are potent tumor promoters in mouse skin. By contrast, bryostatin-1 (bryo-1) isolated from marine bryozoan is a potent PKC activator with little tumor-promoting activity. Numerous investigations have suggested bryo-1 to be a promising therapeutic candidate for the above intractable diseases. However, there is a supply problem of bryo-1 both from natural sources and by organic synthesis. Recent approaches on the synthesis of bryo-1 have focused on its simplification, without decreasing the ability to activate PKC isozymes, to develop new medicinal leads. Another approach is to use the skeleton of natural PKC ligands to develop bryo-1 surrogates. We have recently identified 10-methyl-aplog-1 (26), a simplified analog of tumor-promoting aplysiatoxin (ATX), as a possible therapeutic lead for cancer. This review summarizes recent investigations on the simplification of natural PKC ligands, bryo-1 and ATX, to develop potential medicinal leads

Improved and large-scale synthesis of 10-methyl-aplog-1, a potential lead for an anticancer drug

10-Methyl-aplog-1 (1), a simplified analog of tumor-promoting aplysiatoxin, is a potential lead for cancer therapy that exhibits marked and selective growth inhibitory effects against several human cancer cell lines and negligible tumor-promoting activity in vivo. However, more detailed evaluations of its toxicity and anticancer activity in vivo are hampered by supply problems associated with a non-optimal synthetic method. We here addressed this issue through a more practical and reliable synthetic method that afforded several hundred milligrams of 1 with high purity (>98%) in 23 steps from commercially available m-hydroxycinnamic acid with an overall yield of 1.1%. The utilization of two key reactions, substrate-controlled epoxidation and the oxidative cleavage of alkene with a free hydroxyl group, successfully reduced the existing five synthetic steps and markedly improved the handling of large amounts of intermediates. We also demonstrated for the first time that such an analog was synthetically accessible in reliable quantities and also that this large supply could advance in vivo trials for the treatment of cancer

Practical Enantioselective Reduction of Ketones Using Oxazaborolidine Catalysts Generated In Situ from Chiral Lactam Alcohols

Oxazaborolidine catalyst (CBS catalyst) has been extensively used for catalytic borane reduction with a predictable absolute stereochemistry and high enantioselectivity. However, the use of isolated CBS catalyst sometimes has the drawback of low reproducibility due to the aging of the CBS catalyst during storage. Therefore, we investigated a more reliable and practical method for the reduction of a variety of ketones including challenging substrates, primary aliphatic ketones, &alpha;,&beta;-enones, and trifluoromethyl ketones. This review surveys the developments in borane reduction using oxazaborolidine catalysts generated in situ from chiral lactam alcohols and borane

Role of the phenolic hydroxyl group in the biological activities of simplified analogue of aplysiatoxin with antiproliferative activity.

The 18-deoxy derivative (3) of a simplified analogue (1) of aplysiatoxin with antiproliferative activity was synthesized to examine the role of the phenolic hydroxyl group at position 18 in the biological activities of 1. Compound 3 as well as 1 showed significant affinity for protein kinase Cδ (PKCδ), and the antiproliferative activity of 3 was slightly higher than that of 1. However, the anti-tumor-promoting activity of 3 was less than that of 1 in vitro, suggesting that the phenolic hydroxyl group of 1 is necessary for the anti-tumor-promoting activity but not for the binding of PKCδ and antiproliferative activity. Moreover, PKC isozyme selectivity of 3 was similar to that of 1, suggesting non-PKC receptors for these compounds to play some roles in the anti-tumor-promoting activity of 1

Structural optimization of 10-methyl-aplog-1, a simplified analog of debromoaplysiatoxin, as an anticancer lead

Aplog-1 is a simplified analog of debromoaplysiatoxin (DAT) with potent tumor-promoting and proinflammatory activities. Aplog-1 and DAT exhibited anti-proliferative activities against several human cancer cell lines, whereas aplog-1 did not have tumor-promoting nor proinflammatory activities. We have recently found 10-methyl-aplog-1 (1) to have strong anti-proliferative activity compared with aplog-1. To further investigate the structural factors involved in the tumor-promoting, proinflammatory, and anti-proliferative activities, two dimethyl derivatives of aplog-1 (2, 3) were synthesized, where two methyl groups were installed at positions 4 and 10 or 10 and 12. 10,12-Dimethyl-aplog-1 (2) had stronger inhibitory effects on the growth of several human cancer cell lines than 1 and DAT, but exhibited no tumor-promoting and proinflammatory activities. In contrast, 4,10-dimethyl-aplog-1 (3) displayed weak tumor-promoting and proinflammatory activities along with anti-proliferative activity similar to that of 1 and DAT. Compound 2 would be the optimized seed for anticancer drugs among the simplified analogs of DAT

Synthesis and structure–activity studies of simplified analogues of aplysiatoxin with antiproliferative activity like bryostatin-1

Protein kinase C (PKC) isozymes are promising targets for anticancer therapy. Bryostatin-1 (bryo-1), a unique PKC activator with little tumor-promoting activity, is currently in clinical trials for the treatment of cancer. However, its limited availability from natural sources and its synthetic complexity have hampered studies of its mode of action and structural optimization as a therapeutic agent. The development of synthetically more accessible compounds with bryo-1-like activities is thus needed. Recently, we developed a simple and less lipophilic analogue of tumor-promoting aplysiatoxin (ATX) (aplog-1) as a promising lead for bryo-1-like anticancer drugs. Structure–activity studies suggested that local hydrophobicity around the spiroketal moiety of aplog-1 is a crucial determinant of its antiproliferative activity. The hydrophobic analogue (12,12-dimethyl-aplog-1) displayed more potent antiproliferative activity. Moreover, it showed little tumor-promoting activity and even suppressed the tumor promotion by 12-O-tetradecanoylphorbol 13-acetate (TPA) in vivo and in vitro. Aplog-1 and bryo-1 bound selectively to novel PKC isozymes (δ, η, and θ) while tumor promoters bound to both conventional and novel PKC isozymes. These results suggest that the unique biological activities of aplog-1 and bryo-1 are ascribable in part to the ability to bind to PKCδ, but weak binding to conventional PKC isozymes might also be important