ß1 integrin controls EGFR signaling and tumorigenic properties of lung cancer cells.

Lung cancer is the leading cause of cancer death worldwide. The epidermal growth factor receptor (EGFR) represents the main target for non-small cell lung cancer (NSCLC) therapy, as its overexpression or constitutive activation contributes to malignancy and correlates with poor prognosis. Our previous work demonstrated that in epithelial cells ß1 integrin is required for propagating EGFR signaling from the plasma membrane to the nucleus. In this study, we silenced ß1 integrin in human NSCLC A549 cells. The ß1 integrin-silenced cells show a defective activation of the EGFR signaling cascade, leading to decreased in vitro proliferation, enhanced sensitivity to cisplatin and Gefitinib, impaired migration and invasive behavior. Inhibitory effects on tumor growth and on the EGFR pathway were also observed in in vivo experiments. Moreover, ß1 integrin silencing increases the amount of EGFR on the cell surface, suggesting that ß1 integrin is required for efficient constitutive EGFR turnover at the cell membrane. Although the rate of EGF internalization and recycling is not affected in silenced cells, EGFR signaling is recovered only by expression of the Rab-coupling protein RCP, indicating that ß1 integrin sustains the endocytic machinery required for EGFR signaling. Overall, these results show that ß1 integrin is an essential regulator of EGFR signaling and tumorigenic properties of lung cancer cells, and that its silencing might represent an adjuvant approach to anti-EGFR therapy.

p140Cap dual regulation of E-cadherin/EGFR cross-talk and Ras signalling in tumour cell scatter and proliferation.

The adaptor protein p140Cap/SNIP is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase (Csk). Here, by gain and loss of function approaches in breast and colon cancer cells, we report that p140Cap immobilizes E-cadherin at the cell membrane and inhibits EGFR and Erk1/2 signalling, blocking scatter and proliferation of cancer cells. p140Cap-dependent regulation of E-cadherin/EGFR cross-talk and cell motility is due to the inhibition of Src kinase. However, rescue of Src activity is not sufficient to restore Erk1/2 phosphorylation and proliferation. Indeed, p140Cap also impairs Erk1/2 phosphorylation by affecting Ras activity, downstream to the EGFR. In conclusion, p140Cap stabilizes adherens junctions and inhibits EGFR and Ras signalling through the dual control of both Src and Ras activities, thus affecting crucial cancer properties such as invasion and growth. Interestingly, p140Cap expression is lost in more aggressive human breast cancers, showing an inverse correlation with EGFR expression. Therefore, p140Cap mechanistically behaves as a tumour suppressor that inhibits signalling pathways leading to aggressive phenotypes.

Effectiveness and safety of hypnotic drugs in the treatment of insomnia in over 70-year old people.

Good sleep is an important index of the quality of life in people and above all in old subjects. Among all the symptoms reported to general practitioner, insomnia is at the 3(rd) place and this is present in particular in the elderly. In elderly people high comorbidity and polytreatment are often present. We have studied 60 elderly people with history of insomnia and concomitant diseases: depression, dementia and behavioral disturbances. All the patients of the present study were visited in our outpatients' department. Three hypnotic drugs were used for the treatment of insomnia: zolpidem, or triazolam, or oxazepam, respectively at doses of 10mg/day, 0.125-0.25mg/day and 15.0mg/day. All the three drugs showed to be effective and safe; no paradoxical effects were observed.

Use of zolpidem in over 75-year-old patients with sleep disorders and comorbidities.

The aim of the present study was to evaluate the efficacy and safety of zolpidem in elderly subjects with disorders of sleep and comorbidities. The patients of this study had to present the following requirements: age over 70 years, reported disorders of sleep such as insomnia, and they had to be affected with diabetes and arterial hypertension. Patients presenting diseases that could interfere with sleep, i.e., anxiety, depression, panic attacks,alcohol abuse, some drugs were excluded from the study. All the jobs potentially causing insomnia carried out in the past from the patients were considered, too. A questionnaire of sleep was administered to all the patients (World Psychiatric Association: WPA, 1971).Insomnia, whenever present, was classified according to the criteria of the American Sleep Disorders (ASD) Society and the American Professional Sleep Society (APSS). The following scales were also administered: instrumental activities of daily living scale (IADL),activities of daily living (ADL), geriatric depression scale (GDS), cumulative illness rating scale (CIRS), short portable mental status questionnaire (SPMSQ), mini nutritional assessment (MNA), disease medical index (DMI), sleep questionnaire, social and environmental status. Two groups of patients were evaluated. Group A: 50 patients, 35 women and 15 men, mean age 78.9 years, with a history of insomnia, and Group B 30 patients, 20 women and 10 men, mean age 78.4 years, with onset of insomnia in the last three weeks. The two groups were further divided into three subgroups, diabetic, hypertensive and healthy patients. Zolpidem showed to be effective and well tolerated in both groups of patients.

Integrin regulation of epidermal growth factor (EGF) receptor and of EGF-dependent responses.

Integrin signalling co-ordinates with signalling originating from growth factor receptors in the co-operative control of cell proliferation, survival and migration. Increasing evidence suggests that integrins form physical complexes at the cell membrane with growth factor receptors, giving rise to signalling platforms at the adhesive sites. It is probable that at these sites integrins regulate adhesion and at the same time physically constrain and direct the response to soluble growth factors towards proliferation or survival stimuli. These co-operative effects might depend on integrin ability to activate growth factor receptors. In the present paper, we summarize our recent study showing that integrin-dependent adhesion triggers ligand-independent EGFR (epidermal growth factor receptor) activation to transduce downstream signalling. In addition, we also show that integrin-induced signalling pathways are necessary for EGF-dependent transcriptional response, demonstrating the requirement of the co-operation between cell-matrix adhesion and EGFR to achieve full biological responses.

A PKC-eta/Fyn-dependent pathway leading to keratinocyte growth arrest and differentiation.

Growth control of epithelial cells differs substantially from other cell types. Activation of Fyn, a Src kinase family member, is required for normal keratinocyte differentiation. We report that increased Fyn activity by itself suppresses growth of keratinocytes, but not dermal fibroblasts, through downmodulation of EGF receptor (EGFR) signaling. Protein kinase C-eta has also been implicated in keratinocyte growth/differentiation control. We show that growth suppression of keratinocytes by PKC-eta depends mostly on Fyn. PKC-eta activity is both necessary and sufficient for Fyn activation, PKC-eta and Fyn are found in association, and recombinant PKC-eta directly activates Fyn. Thus, our findings reveal a direct cross talk between PKC-eta and Fyn, which presides over the decision between keratinocyte (epithelial) cell growth and differentiation.

Differential onset of expression of alpha 7 and beta 1D integrins during mouse heart and skeletal muscle development.

beta 1D is a recently identified isoform of the beta 1 integrin subunit selectively expressed in skeletal and cardiac muscles. In the present study we determined the temporal expression of beta 1D and its association with alpha subunits during mouse development. By immunohistochemistry and western blot analysis we demonstrated that beta 1D begins to be expressed in skeletal muscles of 17 days embryo (stage E17). Its level progressively increases reaching maximal values few days after birth and remaining high in adult mice. At earlier stages of development (E11-E17) the beta 1A isoform is expressed in skeletal muscle cells. After E17 beta 1A is downregulated and disappears from muscle fibers few days after birth. In cardiac muscle the regulation of the beta 1D expression is different: beta 1D and beta 1A are coexpressed in the heart of E11 embryo. Subsequently expression of beta 1A declines, while beta 1D increases until it becomes the unique beta 1 isoform in cardiomyocytes few days after birth. Previous studies (Belkin et al J. Cell Biol. 132: 211-226, 1996) demonstrated that beta 1D in adult mouse cardiomyocytes is exclusively associated with alpha 7B. Western blot analysis shows that alpha 7B starts to be expressed in the heart only at stage E17, while beta 1D is expressed already at E11 embryo, indicating that alpha subunits other than alpha 7 should associate with beta 1D in early developmental stages. To investigate this aspect, beta 1 associated alpha subunits were identified by western blotting from cardiomyocytes integrin complexes immunoprecipitated with alpha subunit specific antibodies. We found that, during cardiomyocyte development, beta 1D associates with several alpha subunits namely with alpha 5, alpha 6A and alpha 7B. In conclusion these data show that the expression of the beta 1D muscle specific integrin during development occurs much earlier in heart than in skeletal muscle and it can dimerize with different alpha subunits.

Tyrosine phosphorylation and src family kinases control keratinocyte cell-cell adhesion.

In their progression from the basal to upper differentiated layers of the epidermis, keratinocytes undergo significant structural changes, including establishment of close intercellular contacts. An important but so far unexplored question is how these early structural events are related to the biochemical pathways that trigger differentiation. We show here that beta-catenin, gamma-catenin/plakoglobin, and p120-Cas are all significantly tyrosine phosphorylated in primary mouse keratinocytes induced to differentiate by calcium, with a time course similar to that of cell junction formation. Together with these changes, there is an increased association of alpha-catenin and p120-Cas with E-cadherin, which is prevented by tyrosine kinase inhibition. Treatment of E-cadherin complexes with tyrosine-specific phosphatase reveals that the strength of alpha-catenin association is directly dependent on tyrosine phosphorylation. In parallel with the biochemical effects, tyrosine kinase inhibition suppresses formation of cell adhesive structures, and causes a significant reduction in adhesive strength of differentiating keratinocytes. The Fyn tyrosine kinase colocalizes with E-cadherin at the cell membrane in calcium-treated keratinocytes. Consistent with an involvement of this kinase, fyn-deficient keratinocytes have strongly decreased tyrosine phosphorylation levels of beta- and gamma-catenins and p120-Cas, and structural and functional abnormalities in cell adhesion similar to those caused by tyrosine kinase inhibitors. Whereas skin of fyn-/- mice appears normal, skin of mice with a disruption in both the fyn and src genes shows intrinsically reduced tyrosine phosphorylation of beta-catenin, strongly decreased p120-Cas levels, and important structural changes consistent with impaired keratinocyte cell adhesion. Thus, unlike what has been proposed for oncogene-transformed or mitogenically stimulated cells, in differentiating keratinocytes tyrosine phosphorylation plays a positive role in control of cell adhesion, and this regulatory function appears to be important both in vitro and in vivo.