Targeting of nuclear factor kappaB Pathways by dehydroxymethylepoxyquinomicin, a novel inhibitor of breast carcinomas: antitumor and antiangiogenic potential in vivo.

We previously designed and synthesized the new nuclear factor kappaB (NF-kappaB) inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) derived from the structure of the antibiotic epoxyquinomicin C. We looked into the effect of DHMEQ on cellular phenotypes and tumor growth in mice injected with human breast carcinoma cell line MDA-MB-231 or MCF-7. In estrogen-independent breast adenocarcinoma cell line MDA-MB-231, NF-kappaB is constitutively activated. The addition of DHMEQ (10 microg/mL) completely inhibited the activated NF-kappaB for at least 8 hours. On the other hand, NF-kappaB is not activated in estrogen-dependent MCF-7 cells. In this cell line, DHMEQ completely inhibited the tumor necrosis factor-alpha-induced activation of NF-kappaB. DHMEQ did not inhibit the degradation of IkappaB but inhibited the nuclear translocation of NF-kappaB by both p65/p50 and RelB/p52 pathways. MDA-MB-231 cells secrete interleukin (IL)-6 and IL-8 without stimulation, and DHMEQ decreased the secretion levels of both cytokines. When MDA-MB-231 or MCF-7 cells were stimulated by tumor necrosis factor-alpha, the inhibitory effects of DHMEQ were still maintained. I.p. administration of DHMEQ (thrice a week) significantly inhibited the tumor growth of MDA-MB-231 (12 mg/kg) or MCF-7 (4 mg/kg) in severe combined immunodeficiency mice. No toxicity was observed during the experiment, including the loss of body weight. An immunohistological study on resected MCF-7 tumors showed that DHMEQ inhibited angiogenesis and promoted apoptosis. Furthermore, in Adriamycin-resistant MCF-7 cells highly expressing multidrug resistance gene-1, DHMEQ also exhibited the above capability, including down-regulation of IL-8. Thus, DHMEQ might be a potent drug for the treatment of various breast carcinomas by inhibiting the NF-kappaB activity.     

A crucial role of uridine/cytidine kinase 2 in antitumor activity of 3'-ethynyl nucleosides.

The antitumor 3'-ethynyl nucleosides, 1-(3-C-ethynyl-beta-D-ribopentofuranosyl)cytosine (ECyd) and 1-(3-C-ethynyl-beta-D-ribopentofuranosyl)uridine (EUrd), are potent inhibitors of RNA polymerases and show excellent antitumor activity against various human solid tumors in xenograft models. ECyd is being investigated in phase I clinical trials as a novel anticancer drug possessing a unique antitumor action. ECyd and EUrd require the activity of uridine/cytidine kinase (UCK) to produce the corresponding active metabolite. The UCK family consists of two members, UCK1 and UCK2, and both UCKs are expressed in many tumor cells. It was unclear, however, whether UCK1 or UCK2 is responsible for the phosphorylation of the 3'-ethynyl nucleosides. We therefore established cell lines that are highly resistant to the 3'-ethynyl nucleosides from human fibrosarcoma HT-1080 and gastric carcinoma NUGC-3. All the resistant cell lines showed a high cross-resistance to ECyd and EUrd. As a result of cDNA sequence analysis, we found that UCK2 mRNA expressed in EUrd-resistant HT-1080 cells has a 98-base pair deletion of exon 5, whereas EUrd-resistant NUGC-3 cells were harboring the point mutation at nucleotide position 484 (C to T) within exon 4 of UCK2 mRNA. This mutation was confirmed by genome sequence analysis of the UCK2 gene. Moreover, the expression of UCK2 protein was decreased in these resistant cells. In contrast, no mutation in the mRNA or differences in protein expression levels of UCK1 were shown in the EUrd-resistant HT-1080 and NUGC-3 cells. These results suggest that UCK2 is responsible for the phosphorylation and activation of the antitumor 3'-ethynyl nucleosides.     

Synergistic effects of topoisomerase I inhibitor, 7-ethyl-10-hydroxycamptothecin, and irradiation in a cisplatin-resistant human small cell lung cancer cell line.

7-ethyl-10-[4-(1-piperidyl)-1-piperidyl] carbonyloxy-camptothecin, a topoisomerase I (topo I) inhibitor, is one of the most active agent against lung cancer, and its radiosensitizing effect has been reported recently. We evaluated a combination in vitro effect of irradiation and 7-ethyl-10-hydroxy-CPT (SN-38), an active metabolite of 7-ethyl-10-[4- (1-piperidyl)-1-piperidyl] carbonyloxy-camptothecin, on a human small cell lung cancer cell line (SBC-3) and its cisplatin-resistant subline (SBC-3/CDDP). Growth-inhibitory effects of irradiation with or without SN-38 were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. A modified isobologram method was used to evaluate the treatment interaction. The combination of irradiation and SN-38 showed a synergistic inhibitory effect on the growth of SBC-3/CDDP despite its cross-resistance to irradiation and SN-38. In contrast, the same combination showed only an additive effect on the growth of parental SBC-3 cells. There was no significant difference in topo I protein expression between these two cell lines. In SBC-3 cells, topo I catalytic activity was suppressed by 4 Gy of irradiation, without a decrease of nuclear topo I protein, whereas the exposure of SBC-3 cells to 1 microM SN-38 subsequent to irradiation showed no remarkable additional effects on both topo I activity and protein content. On the other hand, in SBC-3/CDDP cells, topo I activity was unchanged by irradiation, but the subsequent exposure to SN-38 gave rise to a decrease in topo I activity, which was accompanied by a significant decrease in the topo I protein content (P = 0.02). These observations may indicate that SN-38 induces sequestration of topo I onto DNA in radiation-treated SBC-3/CDDP cells and suggest that the synergistic effect of irradiation and SN-38 in SBC-3/CDDP cells was considered attributable to DNA repair-related enhanced recruitment of topo I onto the damaged DNA.     

From antenna to reaction center: Pathways of ultrafast energy and charge transfer in photosystem II

The photosystem II core complex (PSII-CC) is the smallest subunit of the oxygenic photosynthetic apparatus that contains core antennas and a reaction center, which together allow for rapid energy transfer and charge separation, ultimately leading to efficient solar energy conversion. However, there is a lack of consensus on the interplay between the energy transfer and charge separation dynamics of the core complex. Here, we report the application of two-dimensional electronic-vibrational (2DEV) spectroscopy to the spinach PSII-CC at 77 K. The simultaneous temporal and spectral resolution afforded by 2DEV spectroscopy facilitates the separation and direct assignment of coexisting dynamical processes. Our results show that the dominant dynamics of the PSII-CC are distinct in different excitation energy regions. By separating the excitation regions, we are able to distinguish the intraprotein dynamics and interprotein energy transfer. Additionally, with the improved resolution, we are able to identify the key pigments involved in the pathways, allowing for a direct connection between dynamical and structural information. Specifically, we show that C505 in CP43 and the peripheral chlorophyll Chlz_D1 in the reaction center are most likely responsible for energy transfer from CP43 to the reaction center.

Photosynthesis is the process through which solar energy is converted into chemical energy (1–3). Photosystem II (PSII), a pigment–protein complex found in cyanobacteria, algae, and land plants, is the site of water splitting and is therefore crucial for photosynthetic function (4–6). It is connected with a large light-harvesting antenna system that collects solar energy and transfers the energy to the reaction center (RC), where charge separation (CS) occurs. Unlike the antenna system of purple bacteria that has a clear energy funnel, the PSII antenna system has a more complicated composition and a very complex energy landscape (4–7). These features allow for regulation that responds to rapid environmental fluctuations and protect the organisms in, for example, excess light, while maintaining highly efficient electronic energy transfer (EET) under optimal conditions (8). To understand the intricate interactions between the subunits that allow for the robustness of this photosynthetic system, the first step is to understand how the antenna system is connected to the RC. The PSII core complex (PSII-CC) is the smallest unit in which the RC is connected to the antenna proteins. It is a dimeric pigment–protein complex in which each monomer contains an RC and two core antenna proteins, namely, CP43 and CP47 (1, 7). These core antennas not only harvest solar energy but also act as the crucial bridge between the peripheral light-harvesting antenna system and the RC. Fig. 1A shows the pigment arrangement of the PSII-CC. The RC, consisting of the D1 and D2 branches, binds the following pigments: 1) two special pair chlorophyll a (P_D1 and P_D2), 2) two accessory chlorophyll a (Chl_D1 and Chl_D2), 3) two pheophytin a (Pheo_D1 and Pheo_D2), and 4) two peripheral chlorophyll a (Chlz_D1 and Chlz_D2) (9, 10). Despite the similarity between the D1 and D2 branches, CS occurs only along the D1 branch (11, 12). CP43, one of the two core antenna proteins, contains 13 chlorophyll a (Chls) and is located closer to the D1 active branch. CP47 contains 16 Chls and is located closer to the D2 branch (10). Together, these proteins provide highly effective EET and CS, which are key to the high quantum yield of CS in the RC.Open in a separate windowFig. 1.(A) Pigment arrangement of monomeric PSII-CC (whereas it is typically found as a dimer) depicted based on the cryoelectron microscopy structure (3JCU) reported by Wei et al. (10). The pigments of CP43, RC, and CP47 are shown in green, blue, and red, respectively. (B) Corresponding excitonic energy levels of monomeric PSII-CC color coded to match pigments in A (55–57). The gray shaded regions in the background represent the three groups based on similar characteristic dynamics. Note that the boundaries between the groups provide only a rough separation region as the dynamical behaviors change gradually along ω_exc. The asterisk (for the RC state) indicates an optically dark state.Despite the importance of the PSII-CC, its early time dynamics is not fully understood—specifically the competition between EET and CS (5, 7). This is largely due to the highly congested excitonic manifold (Fig. 1B) and ultrafast EET timescales, which challenge ultrafast spectroscopic techniques. Two distinct models have been put forth to try to describe the function of the PSII-CC. These two models are the “exciton/radical pair equilibrium” (ERPE) model (13–17) and the “transfer-to-trap limited” (TTTL) model (18–22). An early fluorescence decay experiment (13, 14) suggested that rapid EET allows the excitonic states to reach an equilibrium between the core antennas and the RC before CS occurs (k_EET ≫ k_CS), which is the basis for the ERPE model. This model was later supported by improved time-resolved fluorescence (15) and transient absorption experiments (16). However, a major discrepancy in this model arose with the measurement of the X-ray crystal structure of the PSII-CC (18). It was suggested that the large distances (center-to-center distance, >20 Å) between antenna and RC pigments resolved in the crystal structure would mean that ultrafast EET between the antenna proteins and the RC is unlikely. A model was then put forth that instead suggested that the EET from the core antenna to the RC is slow compared to CS (k_EET ≪ k_CS), and therefore, the EET to the trap becomes a kinetic bottleneck (18). This TTTL model was later supported by transient infrared (IR) (19) and time-resolved fluorescence experiments (20, 21) as well as structure-based simulations (22). Additionally, Kaucikas et al. (23) performed a polarized transient IR experiment on an oriented single PSII-CC crystal. The decay of the polarization-dependent signature (50–100 ps) observed in their experiment suggests that equilibration between different subunits is slow, consistent with the TTTL model. However, it has been pointed out that satisfactory fitting of the spectral evolution to this model does not necessarily imply that it is correct (24, 25), especially as others have shown that the EET dynamics cannot be adequately described by a single hopping scheme (26, 27). A recent two-dimensional electronic spectroscopy (2DES) experiment (28) with improved time resolution has also revealed the existence of ultrafast EET (<100 fs) that was not predicted by theoretical calculations. In their work, Pan et al. (28) attributed the origin of this unexpectedly fast EET pathway to polaron formation. Vibronic effects on the ultrafast EET and CS dynamics of other photosynthetic proteins have also been discussed (29–38).The lack of detailed understanding of the PSII-CC early time dynamics, in particular the EET between the core antennas and the RC, highlights the need for further experimental input with the ability to make specific assignments of the dynamical pathways. This, however, requires simultaneous high temporal and spectral resolution, which remains a challenge for ultrafast spectroscopic techniques. Here, we describe the application of two-dimensional electronic-vibrational (2DEV) spectroscopy (39–41) to the PSII-CC. The combination of both spectral dimensions provides an improved resolution that allows us to obtain much more detailed dynamical information in complex systems. The excitonic energy landscapes generated by electronic coupling in photosynthetic complexes, combined with site-dependent and charge state–dependent vibrational spectra, allow the resolution along both axes of 2DEV spectra to provide a direct connection between energetic space (via visible excitation) and physical space (via IR detection). This advantage has proven to be useful for the studies of dynamics in photosynthetic pigment–protein complexes (33, 40–45). Specifically, the resolution along the electronic excitation axis allows for the separation of the contributions from different pathways, while the resolution along the vibrational detection axis provides a way to identify the protein subunits or even specific states involved in the dynamics. As we will show, this unique feature of 2DEV spectroscopy provides insight into the complex dynamics of the PSII-CC.In the following text, we will show that the sub-100-ps dynamics of the PSII-CC extracted from spinach are highly dependent on the excitation frequency range. The resolution along the detection axis allows different dominant dynamics to be identified. In addition, we will demonstrate how 2DEV spectroscopy allows us to connect the observed dynamics to specific excitonic states. This connection allows us to obtain a more specific pigment assignment for the EET pathways and therefore provides a more detailed understanding of the finely tuned interactions between the RC and the core antennas (specifically CP43, which is closer to the active D1 branch). We will conclude with a comparison between our results and the existing models in order to provide a path forward in the understanding of this critical photosynthetic component.     

Ivabradine as an Adjuvant Agent for Severe Heart Failure Occurring in the Early Phase after Allogeneic Hematopoietic Cell Transplantation

Cardiotoxicity is a critical complication of allogeneic hematopoietic cell transplantation (allo-HCT). In particular, management of severe cardiotoxicity occurring in the early phases of allo-HCT is challenging. We encountered a case of severe cardiotoxicity resulting from AHF six days after allo-HCT, which resisted catecholamines and diuretics. The patient was treated with anthracycline-containing regimens and underwent myeloablative conditioning, including high-dose cyclophosphamide. As invasive circulatory assisting devices were contraindicated because of his immunocompromised status and bleeding tendency, we successfully treated the patient with ivabradine-containing medications. Ivabradine may therefore be considered an alternative drug for the treatment of severe cardiotoxicity induced by cytotoxic agents.     

Association between maternal gestational diabetes mellitus and high‐sensitivity C‐reactive protein levels in 8‐year‐old children: The Yamanashi Adjunct Study of the Japan Environment and Children’s Study (JECS)

Gestational diabetes mellitus (GDM) is one of the most common pregnancy‐related complications; it is associated with adverse pregnancy outcomes and metabolic disorders in offspring, consistent with the concept of the developmental origins of health and disease. This cohort study of women without diabetes (n = 761), who were part of the Yamanashi Adjunct Study of the Japan Environment and Children’s Study, aimed to explore the associations between maternal GDM and their offspring’s level of high‐sensitivity C‐reactive protein (hsCRP), a biomarker of inflammatory and cardiovascular diseases. We analyzed the associations between GDM and the offspring’s hsCRP levels using a multiple logistic regression model. A mother with GDM significantly increased the risk for high hsCRP level by 4.07‐fold (≥2.0 mg/L) in the child. As such, maternal GDM was significantly associated with increased serum hsCRP levels in 8‐year‐old children.