Role of TGF-ß in metastatic colon cancer: it is finally time for targeted therapy.

Colorectal cancer (CRC) is one of the most frequent tumor types in Western countries. Approximately 20 % of patients show metastasis at the time of diagnosis, with the liver being one of the most affected organs. Transforming growth factor-beta (TGF-ß) plays a regulatory role not only in the physiology of the normal colon but also in the development of CRC and its metastatic process. In this review, we analyze the molecular mechanisms leading to TGF-ß dysregulation in tumor and stroma cells and the modification of the microenvironment that fosters CRC metastasis. Recent genomic studies have identified a CRC subtype with a mesenchymal and aggressive phenotype having TGF-ß as a hub gene of this signature. Consistent with these findings, the inhibition of TGF-ß signaling has been shown to impair experimental CRC metastasis to the liver. Based on these and other results conducted in various tumor types, the pharmaceutical industry has developed a variety of strategies to target TGF-ß. We provide up-to-date information of these therapies, which are currently in preclinical or clinical trials.

TMPRSS4 induces cancer stem cell-like properties in lung cancer cells and correlates with ALDH expression in NSCLC patients.

Metastasis involves a series of changes in cancer cells that promote their escape from the primary tumor and colonization to a new organ. This process is related to the transition from an epithelial to a mesenchymal phenotype (EMT). Recently, some authors have shown that migratory cells with an EMT phenotype share properties of cancer stem cells (CSCs), which allow them to form a new tumor mass. The type II transmembrane serine protease TMPRSS4 is highly expressed in some solid tumors, promotes metastasis and confers EMT features to cancer cells. We hypothesized that TMPRSS4 could also provide CSC properties. Overexpression of TMPRSS4 reduces E-cadherin and induces N-cadherin and vimentin in A549 lung cancer cells, supporting an EMT phenotype. These changes are accompanied by enhanced migration, invasion and tumorigenicity in vivo. TMPRSS4 expression was highly increased in a panel of lung cancer cells cultured as tumorspheres (a typical assay to enrich for CSCs). H358 and H441 cells with knocked-down TMPRSS4 levels were significantly less able to form primary and secondary tumorspheres than control cells. Moreover, they showed a lower proportion of ALDH+ cells (examined by FACS analysis) and lower expression of some CSC markers than controls. A549 cells overexpressing TMPRSS4 conferred the opposite phenotype and were also more sensitive to the CSC-targeted drug salinomycin than control cells, but were more resistant to regular chemotherapeutic drugs (cisplatin, gemcitabine and 5-fluorouracil). Analysis of 70 NSCLC samples from patients revealed a very significant correlation between TMPRSS4 expression and CSC markers ALDH (p = 0.0018) and OCT4 (p = 0.0004), suggesting that TMPRSS4 is associated with a CSC phenotype in patients' tumors. These results show that TMPRSS4, in addition to inducing EMT, can also promote CSC features in lung cancer; therefore, CSC-targeting drugs could be an appropriate treatment for TMPRSS4+ tumors.

Feedback-independent Pt nanoelectrodes for shear force-based constant-distance mode scanning electrochemical microscopy.

A new generation of platinum nanoelectrodes for constant-distance mode scanning electrochemical microscopy (CD-SECM) has been prepared, characterized, and used for high spatial resolution electrochemical measurements and visualization of electrochemically induced concentration gradients in microcavities. The probes have long (1-2 cm), narrow quartz tips that were conically polished and have a Pt nanoelectrode that is slightly offset from center. Because of the size and location of the electrode on the probe, it does not exhibit SECM feedback while approaching the analyzed sample surfaces even to distances within a few hundred nanometers. The probe was positioned near the surface while scanning and performing electrochemical measurements through use of nonoptical shear force control of the tip-to-sample distance. Test structures consisted of cylindrically shaped microcavities that are 50 microm in diameter with three individually addressable electrodes: a gold disk at 8-microm depth, a crescent-shaped gold ring at 4-microm depth along the wall, and a top gold electrode at the rim. Different electrodes within the microcavity were used to reduce and oxidize redox species in 250 microL of a solution of 5 mM hexaamineruthenium(III) chloride and 0.1 M potassium chloride, protected from evaporation by mineral oil, while the SECM tip followed the topography of the structures and monitored the current from the oxidation of [Ru(NH3)6]2+. Electrochemically generated concentration profiles were obtained from these complex test structures that are not possible with any other SECM technology at this time.

Analysis in ultrasmall volumes: microdispensing of picoliter droplets and analysis without protection from evaporation.

A new approach is reported for analysis of ultrasmall volumes. It takes advantage of the versatile positioning of a dispenser to shoot approximately 150-pL droplets of liquid onto a specific location of a substrate where analysis is performed rapidly, in a fraction of the time that it takes for the droplet to evaporate. In this report, the site where the liquid is dispensed carries out fast-scan cyclic voltammetry (FSCV), although the detection method does not need to be restricted to electrochemistry. The FSCV is performed at a microcavity having individually addressable gold electrodes, where one serves as working electrode and another as counter/pseudoreference electrode. Five or six droplets of 10 mM [Ru(NH(3))(6)]Cl(3) in 0.1 M KCl were dispensed and allowed to dry, followed by redissolution of the redox species and electrolyte with one or five droplets of water and immediate FSCV, demonstrating the ability to easily concentrate a sample and the reproducibility of redissolution, respectively. Because this approach does not integrate detection with microfluidics on the same chip, it simplifies fabrication of devices for analysis of ultrasmall volumes. It may be useful for single-step and multistep sample preparation, analyses, and bioassays in microarray formats if dispensing and changing of solutions are automated. However, care must be taken to avoid factors that affect the aim of the dispenser, such as drafts and clogging of the nozzle.