Reactive oxygen species produced by photodynamic therapy enhance docosahexaenoic acid lipid peroxidation and induce the death of breast cancer cells.

Breast cancer remains a serious threat to women's physical and emotional health. The combination therapies can overcome the deficiency of single therapy, enhance the therapeutic effects and reduce the side effects at the same time. In this study, we synthesize a novel nanomedicine that enhanced the therapeutic effects of breast cancer treatment by combining photodynamic therapy and chemotherapy. The doxorubicin (DOX) and photosensitizer methyl pyropheophorbide-a (MPPa) are loaded into the nano-drug delivery system as DPSPFA/MPPa/DOX. In response to near-infrared (NIR) laser, the drugs were quickly released to the cancer cells. The MPPa produces reactive oxygen species (ROS) under the action of photodynamics. Unsaturated fatty acids with ROS promotes lipid peroxidation and the combination of chemotherapy and photodynamic therapy. The data shows that the DPSPFA/MPPa/DOX has a spherical shape, good dispersibility and stability, and the particle size is roughly 200 nm. The drug loading capability of DOX is about 13 %. Both of MCF7 cell model in vitro and breast cancer model in vivo, DPSPFA/MPPa/DOX showed an excellent anti-tumor effect of 86.9 % and without any obvious side effects. These findings might offer potential for a new approach for breast cancer treatment.

Toll-like receptor 9 regulates melanogenesis through NF-κB activation.

Toll-like receptors play essential roles in the modulation of melanogenesis, which has been implicated in the pathogenesis of hyper- or hypopigmentation-related diseases. However, little is currently known regarding the role of TLR9 in human melanocytes. TLR9 recognizes unmethylated cytosine-phosphate-guanine motif-containing oligodeoxynucleotides, and cytosine-phosphate-guanine ODN2006 acts as an hTLR9 agonist. The aim of the present study was to investigate the effect of cytosine-phosphate-guanine ODN2006 on melanogenesis in the human melanocyte cells. MTT assay and enzyme-linked immunosorbent assay indicated that ODN2006 stimulation (0, 1, 5, 10 µM) dose-dependently reduced cell viability and promoted the production of TNF-α, IL-6, and IL-8 in PIG1 melanocytes. The mRNA and protein levels of PMEL and TYRosinase were elevated at 6 h, and then decreased 24 h later, but were significantly augmented 72 h later following ODN2006 stimulation; whereas, TLR9 expressions were time-dependently increased in PIG1 melanocytes. Moreover, ultraviolet B irradiation combined with ODN2006 stimulation induced much more significant enhancement of PMEL, TYRosinase, and TLR9 mRNA and protein after three days in PIG1 melanocytes, and the similar results were obtained using the primary human melanocytes. The expression of TLR9 protein was down-regulated by TLR9 siRNA transfection. ODN2006 had an additive effect on ultraviolet B-induced melanogenesis and PMEL expression, as well as NF-κB activation, which could be blocked by TLR9 knockdown, the NF-κB specific inhibitor PDTC, or the TBK1 inhibitor BX795. Collectively, we concluded that TLR9 regulates melanogenesis through NF-κB activation, suggesting that TLR9 may play a role in microbial-induced melanogenesis.

Adenosine A2 receptors are involved in the activation of ATP-sensitive K+ currents during metabolic inhibition in guinea pig ventricular myocytes.

It has been hypothesized that an interaction among adenosine A(1) receptors, protein kinase C (PKC) activation, and ATP-sensitive potassium channels (K(ATP)) mediates ischemic preconditioning in experiments on different animal species. The purpose of this study was to determine if activation of K(ATP) is functionally coupled to A(1) receptors and (or) PKC activation during metabolic inhibition (MI) in guinea pig ventricular myocytes. Perforated-patch using nystatin and conventional whole-cell recording methods were used to observe the effects of adenosine and adenosine-receptor antagonists on the activation of K(ATP) currents during MI induced by application of 2,4-dinitrophenol (DNP) and 2-deoxyglucose (2DG) without glucose, in the presence or absence of a PKC activator, phorbol 12-myristate 13-acetate (PMA). Adenosine accelerated the time course activation of K(ATP) currents during MI under the intact intracellular condition or dialyzed condition with l mmol/L ATP in the pipette solution. The accelerated effect of adenosine activation of K(ATP) under MI was not reversed by a nonselective Al adenosine receptor antagonist, 8-(p-sulfophenyl)theophylline (SPT), or a specific Al adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). However, the adenosine A(2) receptor antagonist alloxazine reversed the time course activation of the K(ATP) current under MI. An adenylate cyclase activator, forskolin, did not further abbreviate the time course activation of K(ATP) with or without adenosine. Application of a PKC blocker, chelerythrine, reversed the time course activation of K(ATP) by adenosine under MI. In addition, pretreatment with a PKC activator, PMA, had similar effects to adenosine, while adenosine did not further shorten the time required for activation of K(ATP) currents during MI with PMA pretreatment. There is no direct evidence of activation of K(ATP) currents by adenosine A(1) receptor during metabolic inhibition under our experimental condition. However, adenosine A(2) receptor activation is involved in the K(ATP) channel activation in the guinea pig ventricular myocytes, of which effect is not mediated through the increase in intracellular cAMP. Adenosine seems to interact with PKC activation to open K(ATP) during MI, but a possible link between the adenosine A(2) receptor and PKC activation in this process needs further elucidation.

Regulation of intrinsic excitability in hippocampal neurons by activity-dependent modulation of the KV2.1 potassium channel.

KV2.1 is the prominent somatodendritic sustained or delayed rectifier voltage-gated potassium (KV) channel in mammalian central neurons, and is a target for activity-dependent modulation via calcineurin-dependent dephosphorylation. Using hanatoxin-mediated block of KV2.1 we show that, in cultured rat hippocampal neurons, glutamate stimulation leads to significant hyperpolarizing shifts in the voltage-dependent activation and inactivation gating properties of the KV2.1-component of delayed rectifier K+ (IK) currents. In computer models of hippocampal neurons, these glutamate- stimulated shifts in the gating of the KV2.1-component of IK lead to a dramatic suppression of action potential firing frequency. Current-clamp experiments in cultured rat hippocampal neurons showed glutamate stimulation induced a similar suppression of neuronal firing frequency. Membrane depolarization also resulted in similar hyperpolarizing shifts in the voltage-dependent gating properties of neuronal IK currents, and suppression of neuronal firing. The glutamate-induced effects on neuronal firing were eliminated by hanatoxin, but not by dendrotoxin-K, a blocker of KV1.1-containing channels. These studies together demonstrate a specific contribution of modulation of KV2.1 channels in the activity-dependent regulation of intrinsic neuronal excitability.