An unusual association of malignant melanoma and small cell lung cancer: case report. An eleven-year-follow-up

The authors report the case of a patient affected by malignant melanoma and small cell lung cancer. After having underlined the rareness of this pathological association, reviewing the most recent literature, the description of the clinical case aims at opening a discussion on how the surgical treatment performed, associated to chemotherapy, brought to an unhoped-for success, also helped by an unexpected combination of events that were absolutely out of any protocol. Eleven years later, at the present follow-up, the patient shows a complete remission of both diseases.

The role of substance P in cerebral ischemia

Tackykinins are involved in the inflammatory process of a large number of diseases. The role of the tachykinins in ischemic brain injury was evaluated by the serum levels of Substance P (SP), one of the most known tachykinins and detected by a competitive enzyme immunoassay. The study was performed in 15 human females and 3 human males with typical manifestation of complete stroke (12 cases) or transient ischemic attack (6 cases). The mean SP level in the serum of patients with transient ischemic attack (0.53+/-0.25 ng/ml) and of patients with complete stroke (0.31+/-0.14 ng/ml), showed significantly higher values than in controls (0.10+/-0.02 ng/ml). Moreover, in transient ischemic attack, the SP values were significantly higher than in cerebral complete stroke. But SP levels, based on the timings of classification of patients (i.e. before 12 hours: 0.34+/-0.15 ng/ml vs. 12 to 24 hours: 0.26+/-0.11 ng/ml) with brain injury, did not show any significant difference. Both values anyway were significantly higher than in controls. Our original results demonstrate the SP increase during cerebral ischemia. Further studies are necessary to verify if SP has an effective physiopathological role in the neurological ischemic damage, or if it is only a concomitant phenomenon. Our data, if confirmed, will be particularly important, not only to improve the knowledge of cerebral ischemic injury, but also for diagnosis and therapeutic approaches.

Ubiquitination and degradation of Syk and ZAP-70 protein tyrosine kinases in human NK cells upon CD16 engagement

Syk and ZAP-70 nonreceptor protein tyrosine kinases (PTKs) are essential elements in several cascades coupling immune receptors to intracellular responses. The critical role of these kinases in promoting the propagation of intracellular signaling requires a tight regulation of their activity, thus the existence of a negative feedback loop regulating their expression can be hypothesized. Herein, we have investigated whether ubiquitin-dependent proteolysis could be a mechanism responsible for controlling the fate of Syk and ZAP-70 after their immunoreceptor-induced activation. We found that both Syk and ZAP-70 become ubiquitinated in response to aggregation of the low affinity Fc receptor for IgG (CD16) on human natural killer cells. We confirmed the identity of the major in vivo ubiquitinated kinase species by performing an in vitro ubiquitination assay. In addition, we found that after CD16 stimulation, ubiquitinated forms of Syk and ZAP-70 associate with the receptor complex. After CD16 engagement, we also observed a decrease in the stability of Syk and ZAP-70 PTKs that is counteracted by pretreatment with either proteasome or lysosomal inhibitors. Moreover, in the presence of the proteasome inhibitor, epoxomicin, we observed an accumulation of ubiquitinated forms of both kinases. Our findings provide evidence of ligand-induced ubiquitination of nonreceptor PTKs belonging to the Syk family and propose the ubiquitin-dependent proteasome-mediated degradation pathway as a mechanism for attenuating the propagation of intracellular signaling initiated by immune receptor engagement.

Tyrosine kinase-dependent ubiquitination of CD16 zeta subunit in human NK cells following receptor engagement

We investigated whether aggregation of the low-affinity immunoglobulin G receptor (CD16) on human NK cells results in receptor ubiquitination. We found that the CD16 zeta subunit becomes ubiquitinated in response to receptor engagement. We then investigated whether protein tyrosine kinase (PTK) activation is required for CD16-mediated receptor ubiquitination. Pretreatment with the PTK inhibitor genistein substantially decreased ligand-induced zeta ubiquitination, suggesting a requirement for PTK activation in receptor ubiquitination. We further analyzed PTK involvement in controlling receptor ubiquitination by using the vaccinia virus expression system. Overexpression of wild-type active lck, but not a kinase-deficient mutant, enhanced both ligand-induced tyrosine phosphorylation and ubiquitination of the CD16 zeta subunit. Taken together, our data demonstrate that CD16 engagement induces zeta chain ubiquitination and strongly suggest a role for lck in regulating this modification.