Inhibition of p38 MAPK Signaling Augments Skin Tumorigenesis via NOX2 Driven ROS Generation

p38 mitogen-activated protein kinases (MAPKs) respond to a wide range of extracellular stimuli. While the inhibition of p38 signaling is implicated in the impaired capacity to repair ultraviolet (UV)-induced DNA damage—a primary risk factor for human skin cancers—its mechanism of action in skin carcinogenesis remains unclear, as both anti-proliferative and survival functions have been previously described. In this study, we utilized cultured keratinocytes, murine tumorigenesis models, and human cutaneous squamous cell carcinoma (SCC) specimens to assess the effect of p38 in this regard. UV irradiation of normal human keratinocytes increased the expression of all four p38 isoforms (α/β/γ/δ); whereas irradiation of p53-deficient A431 keratinocytes derived from a human SCC selectively decreased p38α, without affecting other isoforms. p38α levels are decreased in the majority of human cutaneous SCCs assessed by tissue microarray, suggesting a tumor-suppressive effect of p38α in SCC pathogenesis. Genetic and pharmacological inhibition of p38α and in A431 cells increased cell proliferation, which was in turn associated with increases in NAPDH oxidase (NOX2) activity as well as intracellular reactive oxygen species (ROS). These changes led to enhanced invasiveness of A431 cells as assessed by the matrigel invasion assay. Chronic treatment of p53^-/-/SKH-1 mice with the p38 inhibitor SB203580 accelerated UV-induced SCC carcinogenesis and increased the expression of NOX2. NOX2 knockdown suppressed the augmented growth of A431 xenografts treated with SB203580. These findings indicate that in the absence of p53, p38α deficiency drives SCC growth and progression that is associated with enhanced NOX2 expression and ROS formation.     

High-Resolution Array CGH Profiling Identifies Na/K Transporting ATPase Interacting 2 (NKAIN2) as a Predisposing Candidate Gene in Neuroblastoma

Neuroblastoma (NB), the most common solid cancer in early childhood, usually occurs sporadically but also its familial occurance is known in 1-2% of NB patients. Germline mutations in the ALK and PHOX2B genes have been found in a subset of familial NBs. However, because some individuals harbouring mutations in these genes do not develop this tumor, additional genetic alterations appear to be required for NB pathogenesis. Herein, we studied an Italian family with three NB patients, two siblings and a first cousin, carrying an ALK germline-activating mutation R1192P, that was inherited from their unaffected mothers and with no mutations in the PHOX2B gene. A comparison between somatic and germline DNA copy number changes in the two affected siblings by a high resolution array-based Comparative Genomic Hybridization (CGH) analysis revealed a germline gain at NKAIN2 (Na/K transporting ATPase interacting 2) locus in one of the sibling, that was inherited from the parent who does not carry the ALK mutation. Surprisingly, NKAIN2 was expressed at high levels also in the affected sibling that lacks the genomic gain at this locus, clearly suggesting the existance of other regulatory mechanisms. High levels of NKAIN2 were detected in the MYCN-amplified NB cell lines and in the most aggressive NB lesions as well as in the peripheral blood of a large cohort of NB patients. Consistent with a role of NKAIN2 in NB development, NKAIN2 was down-regulated during all-trans retinoic acid differentiation in two NB cell lines. Taken together, these data indicate a potential role of NKAIN2 gene in NB growth and differentiation.     

Molecular markers in circulating tumour cells from metastatic colorectal cancer patients

The prognosis of metastatic cancer patients is still largely affected by treatment failure, mainly due to drug resistance. The hypothesis that chemotherapy might miss circulating tumour cells (CTCs) and particularly a subpopulation of more aggressive, stem‐like CTCs, characterized by multidrug resistance, has been recently raised. We investigated the prognostic value of drug resistance and stemness markers in CTCs from metastatic colorectal cancer patients treated with oxaliplatin (L‐OHP) and 5‐fluoruracil (5‐FU) based regimens. Forty patients with metastatic colorectal cancer were enrolled. CTCs were isolated from peripheral blood and analysed for the expression of aldheyde dehydrogenase 1 (ALDH1), CD44, CD133 (used as markers of stemness), multidrug resistance related protein 5 (MRP5 used as marker of resistance to 5‐FU and L‐OHP) and survivin (used as a marker of apoptosis resistance). CTCs were found in 27/40 (67%) patients. No correlation was found between the expression of either CD44 and CD133 in CTCs and the outcome of patients, while a statistically significant shorter progression‐free survival was found in patients with CTCs positive for the expression of ALDH1, survivin and MRP5. These results support the idea that isolating survivin and MRP5⁺ CTCs may help in the selection of metastatic colorectal cancer patients resistant to standard 5‐FU and L‐OHP based chemotherapy, for which alternative regimens may be appropriate.     

Undifferentiated MSCs are able to myelinate DRG neuron processes through p75

Over the last few years the therapeutic approach to demyelinating diseases has radically changed, strategies having been developed aimed at partnering the classic symptomatic treatments with the most advanced regenerative medicine tools. At first, the transplantation of myelinogenic cells, Schwann cells or oligodendrocytes was suggested, but the considerable technical difficulties, (poor availability, difficulties in harvesting and culturing, and the problem of rejection in the event of non-autologous sources), shifted attention towards more versatile cellular types, such as Mesenchymal Stem Cells (MSCs). Recent studies have already demonstrate both in vitro and in vivo that glially-primed MSCs (through exposure to chemical cocktails) have myelogenic abilities. In spite of a large number of papers on glially-differentiated MSCs, little is known about the ability of undifferentiated MSCs to myelinate axons and processes. Here we have demonstrated that also undifferentiated MSCs have the ability to myelinate, since they induce the myelination of rat DRG neuron processes after direct co-culturing. In this process a pivotal role is performed by the p75 receptor.     

Sucrose induces arabinogalactan protein secretion by <Emphasis Type="Italic">Beta vulgaris</Emphasis> L. cell suspension cultures

The aim of this study was to determine if the increase of the initial sucrose concentration (ISC) improves cell growth and arabinogalactan protein (AGP) secretion of Beta vulgaris L. cultures. ISC tested were 43.8, 87.6 and 131.4 mM. Cell growth and specific growth rate were improved increasing the ISC. Cell cultures grown with ISC 43.8 mM were fed with sucrose, and cellular growth was enhanced twofold, revealing the stimulatory effect of sucrose on cell growth. The AGP secretion was stimulated, increasing the ISC. This event was partially associated with the exponential growth phase of the culture. AGP precipitation with Yariv reagent of cell cultures inhibited cell growth without changes in viability. The assay of sucrose feeding confirmed the relationship between cell growth and AGP secretion. These observations suggest that AGPs may be required for cell division. The increase of AGP secretion by ISC coincided with a higher cellular aggregation, suggesting a possible role of AGP as cellular adhesion molecules. To determine whether AGP secretion is also stimulated by an osmotic effect, mannitol was fed to raise the osmotic potential from 23.78 to 95.97 mOsm kg⁻¹. Mannitol was not used for cell growth, but AGP secretion was stimulated sixfold in relation to the control. These results are important for understanding the possible factors involved in the AGP secretion of plant cell culture and that may be considered to improve the AGP production.     

Neural processing of gustatory information in insular circuits

The insular cortex is the primary cortical site devoted to taste processing. A large body of evidence is available for how insular neurons respond to gustatory stimulation in both anesthetized and behaving animals. Most of the reports describe broadly tuned neurons that are involved in processing the chemosensory, physiological and psychological aspects of gustatory experience. However little is known about how these neural responses map onto insular circuits. Particularly mysterious is the functional role of the three subdivisions of the insular cortex: the granular, the dysgranular and the agranular insular cortices. In this article we review data on the organization of the local and long-distance circuits in the three subdivisions. The functional significance of these results is discussed in light of the latest electrophysiological data. A view of the insular cortex as a functionally integrated system devoted to processing gustatory, multimodal, cognitive and affective information is proposed.