Low power laser irradiation (LPLI) promotes proliferation of multiple cells, which (especially red and near infrared light) is mainly through the activation of mitochondrial respiratory chain and the initiation of cellular signaling. Recently, the signaling proteins involved in LPLI-induced proliferation merit special attention, some of which are regulated by mitochondrial signaling. Hepatocyte growth factor receptor (c-Met), a member of tyrosine protein kinase receptors (TPKR), is phosphorylated during LPLI-induced proliferation, but tumor necrosis factor alpha (TNF-alpha) receptor has not been affected. Activated TPKR could activate its downstream signaling elements, like Ras/Raf/MEK/ ERK, PI3K/Akt/eIF4E, PI3K/Akt/eNOS and PLC-gamma/PKC pathways. Other two pathways, m/ATP/cAMP/JNK/AP-1 and ROS/Src, are also involved in LPLI-induced proliferation. LPLIinduced cell cycle progression can be regulated by the activation or elevated expressions of cell cycle-specific proteins. Furthermore, LPLI induces the synthesis or release of many molecules, like growth factors, interleukins, inflammatory cytokines and others, which are related to promotive effects of LPLI.

The possibility of performing fast and small-volume nucleic acid amplification and analysis on a single chip has attracted great interest. Devices based on this idea, referred to as micro total analysis, microfluidic analysis, or simply ‘Lab on a chip’ systems, have witnessed steady advances over the last several years. Here, we summarize recent research on chip substrates, surface treatments, PCR reaction volume and speed, architecture, approaches to eliminating cross-contamination and control and measurement of temperature and liquid flow. We also discuss product-detection methods, integration of functional components, biological samples used in PCR chips, potential applications and other practical issues related to implementation of lab-on-a-chip technologies.

Autophagy and apoptosis play important roles in the development, cellular homeostasis and, especially, oncogenesis of mammals. They may be triggered by common upstream signals, resulting in combined autophagy and apoptosis. In other instances, they may be mutually exclusive. Recent studies have suggested possible molecular mechanisms for crosstalk between autophagy and apoptosis. Bcl‐2 and Bcl‐xL, the well‐characterized apoptosis guards, appear to be important factors in autophagy, inhibiting Beclin 1‐mediated autophagy by binding to Beclin 1. In addition, Beclin 1, Bcl‐2 and Bcl‐xL can cooperate with Atg5 or Ca2+ to regulate both autophagy and apoptosis. Thus, Bcl‐2 and Bcl‐xL represent a molecular link between autophagy and apoptosis. Here, we discuss the possible roles of Bcl‐2 and Bcl‐xL in apoptosis and autophagy, and the crosstalk between them.

Mitochondria are dynamic organelles that undergo continual fusion and fission to maintain their morphology and functions, but the mechanism involved is still not clear. Here, we investigated the effect of mitochondrial oxidative stress triggered by high‐fluence low‐power laser irradiation (HF‐LPLI) on mitochondrial dynamics in human lung adenocarcinoma cells (ASTC‐a‐1) and African green monkey SV40‐transformed kidney fibroblast cells (COS‐7). Upon HF‐LPLI‐triggered oxidative stress, mitochondria displayed a fragmented structure, which was abolished by exposure to dehydroascorbic acid, a reactive oxygen species scavenger, indicating that oxidative stress can induce mitochondrial fragmentation. Further study revealed that HF‐LPLI caused mitochondrial fragmentation by inhibiting fusion and enhancing fission. Mitochondrial translocation of the profission protein dynamin‐related protein 1 (Drp1) was observed following HF‐LPLI, demonstrating apoptosis‐related activation of Drp1. Notably, overexpression of Drp1 increased mitochondrial fragmentation and promoted HF‐LPLI‐induced apoptosis through promoting cytochrome c release and caspase‐9 activation, whereas overexpression of mitofusin 2 (Mfn2), a profusion protein, caused the opposite effects. Also, neither Drp1 overexpression nor Mfn2 overexpression affected mitochondrial reactive oxygen species generation, mitochondrial depolarization, or Bax activation. We conclude that mitochondrial oxidative stress mediated through Drp1 and Mfn2 causes an imbalance in mitochondrial fission–fusion, resulting in mitochondrial fragmentation, which contributes to mitochondrial and cell dysfunction.

Indocyanine green (ICG) is a near-infrared (NIR) imaging agent and is also an ideal light absorber for laser-mediated photothermal therapy. This NIR dye could serve as a basis of a dual-functional probe with integrated optical imaging and photothermal therapy capabilities. However, applications of ICG remain limited by its concentration-dependent aggregation, poor aqueous stability, nonspecific binding to proteins and lack of target specificity. To overcome these limitations, a novel ICG-containing nanostructure is designed utilizing the noncovalent self-assembly chemistry between phospholipid-polyethylene glycol (PL-PEG) and ICG. The interactions between both amphiphilic ICG and PL-PEG were studied using absorption and fluorescence spectroscopy. The properties of ICG-PL-PEG nanoprobe, such as absorption and fluorescence spectra, stability, morphology and size distribution, were also investigated. Two representative targeting molecules, namely, a small molecule, folic acid (FA), and a large protein, integrin α(v)β₃ monoclonal antibody (mAb), were conjugated to the surface of ICG-PL-PEG nanoprobe, displaying the diversity of ligand conjugation. The target specificity was confirmed using three cell lines with different levels of available folate receptors (FRs) or integrin α(v)β₃ expression via laser scanning confocal microscope and flow cytometry. This targeting ICG-PL-PEG nanoprobe could be internalized into targeted cells via ligand-receptor mediated endocytosis pathway. Our in vitro experiments showed that internalized ICG-PL-PEG could be used for cell imaging and selective photothermal cell destruction. These results represent the first demonstration of the dual functionality of ICG-containing nanostructure for targeted optical imaging and photothermal therapy of cancerous cells. This novel ICG-PL-PEG nanostructure, when conjugated with other therapeutic and imaging agents, could become a multifunctional probe for cancer diagnosis and treatment.