Antitumor effects of MutT homolog 1 inhibitors in human bladder cancer cells

ABSTRACT

As standard second-line regimen has not been established for patients who are refractory to or relapse with cisplatin-based chemotherapy, an effective class of novel chemotherapeutic agents is needed for cisplatin-resistant bladder cancer. Recent publications reported that MutT homolog 1 (MTH1) inhibitors suppress tumor growth and induce impressive therapeutic responses in a variety of human cancer cells. Few studies investigated the cytotoxic effects of MTH1 inhibitors in human bladder cancer. Accordingly, we investigated the antitumor effects and the possible molecular mechanisms of MTH1 inhibitors in cisplatin-sensitive (T24) and – resistant (T24R2) human bladder cancer cell lines. These results suggest that TH588 or TH287 may induce cancer cell suppression by off-target effects such as alterations in the expression of apoptosis- and cell cycle-related proteins rather than MTH1 inhibition in cisplatin-sensitive and – resistant bladder cancer cells.

Abbreviations: MTH: MutT homolog; ROS: reactive oxygen species; CCK-8: cell counting kit-8; DCFH-DA: dichlorofluorescein diacetate; PARP: poly (ADP-ribose) polymerase     

Isolation of a thermophilic bacterium capable of low-molecular-weight polyethylene degradation

A thermophilic bacterium capable of low-molecular-weight polyethylene (LMWPE) degradation was isolated from a compost sample, and was identified as Chelatococcus sp. E1, through sequencing of the 16S rRNA gene. LMWPE was prepared by thermal degradation of commercial PE in a strict nitrogen atmosphere. LMWPE with a weight-average-molecular-weight (Mw) in the range of 1,700–23,700 was noticeably mineralized into CO₂ by the bacterium. The biodegradability of LMWPE decreased as the Mw increased. The low molecular weight fraction of LMWPE decreased significantly as a result of the degradation process, and thereby both the number-average-molecular-weight and Mw increased after biodegradation. The polydispersity of LMWPE was either narrowed or widened, depending on the initial Mw of LMWPE, due to the preferential elimination of the low molecular weight fraction, in comparison to the high molecular weight portion. LMWPE free from an extremely low molecular weight fraction was also mineralized by the strain at a remarkable rate, and FTIR peaks assignable to C–O stretching appeared as a result of microbial action. The FTIR peaks corresponding to alkenes also became more intense, indicating that dehydrogenations occurred concomitantly with microbial induced oxidation.     

Anticoagulant activities of piperlonguminine in vitro and in vivo

Piperlonguminine (PL), an important component of Piper longum fruits, is known to exhibit anti-hyperlipidemic, antiplatelet and anti-melanogenic activities. Here, the anticoagulant activities of PL were examined by monitoring activatedpartial-thromboplastin-time (aPTT), prothrombin-time (PT), and the activities of thrombin and activated factor X (FXa). The effects of PL on the expressions of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were also tested in tumor necrosis factor-α (TNF-α) activated HUVECs. The results showed that PL prolonged aPTT and PT significantly and inhibited the activities of thrombin and FXa. PL inhibited the generation of thrombin and FXa in HUVECs. In accordance with these anticoagulant activities, PL prolonged in vivo bleeding time and inhibited TNF-α induced PAI-1 production. Furthermore, PAI-1/t-PA ratio was significantly decreased by PL. Collectively, our results suggest that PL possesses antithrombotic activities and that the current study could provide bases for the development of new anticoagulant agents. [BMB Reports 2013; 46(10): 484-489]     

C-terminal truncation of a bovine B12 trafficking chaperone enhances the sensitivity of the glutathione-regulated thermostability

The human B₁₂ trafficking chaperone hCblC is well conserved in mammals and non-mammalian eukaryotes. However, the C-terminal ∼40 amino acids of hCblC vary significantly and are predicted to be deleted by alternative splicing of the encoding gene. In this study, we examined the thermostability of the bovine CblC truncated at the C-terminal variable region (t-bCblC) and its regulation by glutathione. t-bCblC is highly thermolabile (T_m = ∼42℃) similar to the full-length protein (f-bCblC). However, t-bCblC is stabilized to a greater extent than f-bCblC by binding of reduced glutathione (GSH) with increased sensitivity to GSH. In addition, binding of oxidized glutathione (GSSG) destabilizes t-bCblC to a greater extent and with increased sensitivity as compared to f-bCblC. These results indicate that t-bCblC is a more sensitive form to be regulated by glutathione than the full-length form of the protein. [BMB Reports 2013; 46(3): 169-174]     

Biogeographic characteristics of Far Eastern wasps: A case study with eumenine wasps (Hymenoptera: Vespidae: Eumeninae)

A total of 107 forms of 88 eumenine wasp species occurring in the Far East were used to produce a more comprehensive picture of the geographical pattern of wasps in the Far East. All forms occurring in the Far East were biogeographically classified into 22 types in four larger categories, and a summarized table and discussion are presented. The eumenine wasp fauna of the Far East was characterized as a mixture of a fair number of endemic elements, a moderate number of transpalearctic elements, and some Oriental elements. The endemism of the Far East reached 0.71 at the species/subspecies level when the calculation was based on true Palearctic elements occurring in Far Eastern Russia, the Korean peninsula and Japan proper. The relationship between the Far Eastern fauna and the Central/Western Palearctic faunas was also analyzed and discussed. The species occurring in each treated district was counted, and provides evidence for the importance of the Korean fauna in biodiversity evaluation/estimation of Far Eastern fauna. The similarity index between the Korean Peninsula and Japan proper, the Korean Peninsula and the Russian Far East, and the Russian Far East and Japan proper was calculated to explain possible factors for faunal formation in the Far East. The distributional pattern of each form treated in this study and its relatives is tabulated in Appendix I.     

Development of cyan fluorescent protein (CFP) reporter system in green alga Chlamydomonas reinhardtii and macroalgae Pyropia sp.

Various fluorescent proteins have been developed for in vivo reporter systems in diverse prokaryotes and eukaryotes. However, few in vivo imaging systems have been reported for the model algae Chlamydomonas reinhardtii or Pyropia sp. In this study, an effective imaging system using cyan fluorescent protein (CFP) was developed for the green alga C. reinhardtii, and its application was also successful in the red macroalgae Pyropia tenera and P. yezoensis. For optimization of CFP expression in C. reinhardtii and Pyropia sp., we modified codon usage in the CFP gene (CFP), generating PtCrCFP (Pyropia tenera/Chlamydomonas reinhardtii CFP). PtCrCFP was successfully expressed in PtCrCFP-expressing UVM11 transgenic lines, and high accumulation levels of PtCrCFP were found by western blotting. Consistent with these results, PtCrCFP fluorescence was clearly detected with a low level of chlorophyll background fluorescence in PtCrCFP-expressing UVM11 transgenic lines. In Pyropia sp. gametophytic cells, transient expression of PtCrCFP fluorescence was distinctly visualized. PtCrCFP fluorescence was also observed during the regeneration of monospores and young gametophytes from PtCrCFP-expressing P. yezoensis gametophytic cells. These results suggest that PtCrCFP may be useful as an in vivo reporter in green algae due to the short emission wavelength of CFP, which provides a low level of chlorophyll background fluorescence. This study also presents the possibility of PtCrCFP’s use as a visible selection marker for the generation of transgenic lines in the red algae Pyropia sp. Thus, PtCrCFP as an in vivo visualization tool may offer new opportunities for the functional analysis of genetic studies in both green and red algae.