Phosphoinositide 3-kinase (PI3K)/protein kinase B/Akt and Ras/mitogen-activated protein kinase pathways are often constitutively activated in melanoma and have thus been considered as promising drug targets. Exposure of melanoma cells to NVP-BAG956, NVP-BBD130, and NVP-BEZ235, a series of novel, potent, and stable dual PI3K/ mammalian target of rapamycin (mTOR) inhibitors, resulted in complete G1 growth arrest, reduction of cyclin D1, and increased levels of p27 KIP1 , but negligible apoptosis. In contrast, treatment of melanoma with the pan-class I PI3K inhibitor ZSTK474 or the mTORC1 inhibitor rapamycin resulted only in minor reduction of cell proliferation. In a syngeneic B16 mouse melanoma tumor model, orally administered NVP-BBD130 and NVP-BEZ235 efficiently attenuated tumor growth at primary and lymph node metastatic sites with no obvious toxicity. Metastatic melanoma in inhibitor-treated mice displayed reduced numbers of proliferating and significantly smaller tumor cells. In addition, neovascularization was blocked and tumoral necrosis increased when compared with vehicle-treated mice. In conclusion, compounds targeting PI3K and mTOR simultaneously were advantageous to attenuate melanoma growth and they develop their potential by targeting tumor growth directly, and indirectly via their interference with angiogenesis. Based on the above results, NVP-BEZ235, which has entered phase I/II clinical trials in patients with advanced solid tumors, has a potential in metastatic melanoma therapy. (Mol Cancer Res 2009;7(4):601-13)

Bacterial meningitis is characterized by an inflammatory reaction to the invading pathogens that can ultimately lead to sensorineural hearing loss, permanent brain injury, or death. The matrix metalloproteinases (MMPs) and tumor necrosis factor alpha-converting enzyme (TACE) are key mediators that promote inflammation, blood-brain barrier disruption, and brain injury in bacterial meningitis. Doxycycline is a clinically used antibiotic with anti-inflammatory effects that lead to reduced cytokine release and the inhibition of MMPs. Here, doxycycline inhibited TACE with a 50% inhibitory dose of 74 M in vitro and reduced the amount of tumor necrosis factor alpha released into the cerebrospinal fluid by 90% in vivo. In an infant rat model of pneumococcal meningitis, a single dose of doxycycline (30 mg/kg) given as adjuvant therapy in addition to ceftriaxone 18 h after infection significantly reduced the mortality, the blood-brain barrier disruption, and the extent of cortical brain injury. Adjuvant doxycycline (30 mg/kg given subcutaneously once daily for 4 days) also attenuated hearing loss, as assessed by auditory brainstem response audiometry, and neuronal death in the cochlear spiral ganglion at 3 weeks after infection. Thus, doxycycline, probably as a result of its anti-inflammatory properties, had broad beneficial effects in the brain and the cochlea and improved survival in this model of pneumococcal meningitis in infant rats. Pneumococcal meningitis has a high level of mortality (up to 30%), and brain and/or cochlear damage occurs in up to 50% of the survivors (2). Inflammatory mediators, such as tumor necrosis factor alpha (TNF-␣) and matrix metalloproteinases (MMPs), are produced during the host response to bacteria and contribute to the pathophysiology that can ultimately lead to death, brain damage, and hearing impairment (23,26,29,36). The role of cytokines and MMPs in the pathophysiology of the cochlear damage associated with pneumococcal meningitis is still unknown. However, it has been demonstrated that MMPs are constitutively expressed at high levels in the cochlea (8) and that in meningitis pneumococci and polymorphonuclear leukocytes (PMNs) extend from the cerebrospinal fluid (CSF) to the perilymph via the cochlear aqueduct (5).Tetracyclines are bacteriostatic agents with broad-spectrum antimicrobial activity (3). Doxycycline is a semisynthetic, longacting, second-generation tetracycline which is absorbed rapidly and penetrates well into the brain and CSF (48). Doxycycline has been shown to have anti-inflammatory effects that are separate and distinct from its antimicrobial action (13,16,35,43). These effects include the reduction of cytokine release and the inhibition of MMPs (7, 38). Experimental and clinical studies have indicated that treatment with doxycycline may be beneficial in inflammatory diseases associated with excessive MMP activity (7,13,35).In pneumococcal meningitis massive subarachnoid and ventricular space inflammation is triggered by the presence of bacteria in the CSF space (7,1...

Cell activation initiated by receptor ligands or oncogenes triggers complex and convoluted intracellular signaling. Techniques initiating signals at defined starting points and cellular locations are attractive to elucidate the output of selected pathways. Here, we present the development and validation of a protein heterodimerization system based on small molecules cross-linking fusion proteins derived from HaloTags and SNAP-tags. Chemical dimerizers of HaloTag and SNAP-tag (HaXS) show excellent selectivity and have been optimized for intracellular reactivity. HaXS force protein-protein interactions and can translocate proteins to various cellular compartments. Due to the covalent nature of the HaloTag-HaXS-SNAP-tag complex, intracellular dimerization can be easily monitored. First applications include protein targeting to cytoskeleton, to the plasma membrane, to lysosomes, the initiation of the PI3K/mTOR pathway, and multiplexed protein complex formation in combination with the rapamycin dimerization system.

Summary Maintenance of intestinal epithelial barrier function is of vital importance in preventing uncontrolled influx of antigens and the potentially ensuing inflammatory disorders. Intestinal intraepithelial lymphocytes (IEL) are in intimate contact with epithelial cells and may critically regulate the epithelial barrier integrity. While a preserving impact has been ascribed to the T‐cell receptor (TCR)‐γδ subset of IEL, IEL have also been shown to attenuate the barrier function. The present study sought to clarify the effects of IEL by specifically investigating the influence of the TCR‐αβ CD8αβ and TCR‐αβ CD8αα subsets of IEL on the intestinal epithelial barrier integrity. To this end, an in vitro coculture system of the murine intestinal crypt‐derived cell‐line mICcl2 and syngeneic ex vivo isolated IEL was employed. Epithelial integrity was assessed by analysis of transepithelial resistance (TER) and paracellular flux of fluorescein isothiocyanate‐conjugated (FITC‐) dextran. The TCR‐αβ CD8αα IEL and resting TCR‐αβ CD8αβ IEL did not affect TER of mICcl2 or flux of FITC‐dextran. In contrast, activated TCR‐αβ CD8αβ IEL clearly disrupted the integrity of the mICcl2 monolayer. No disrupting effect was seen with activated TCR‐αβ CD8αβ IEL from interferon‐γ knockout mice. These findings demonstrate that secretion of interferon‐γ by activated TCR‐αβ CD8αβ IEL is strictly required and also sufficient for disrupting the intestinal epithelial barrier function.