Relationship between Latitude and Melanoma in Italy

Objective. Evaluate the ecological relationship between skin melanoma epidemiology and latitude in Italy. Methods. We used data from the Italian network of cancer registries (Airtum). In a Poisson model, we evaluated the effect on incidence, mortality, and survival of latitude, adjusting for some demographic, social, phenotypic, and behavioural variables. Results. Incidence increased in Italy by 17% for each degree of increase in latitude. The effect of latitude was statistically significantly present also adjusting for other variables (incidence rate ratio = 1.08). The effect of latitude on increasing mortality (mortality rate ratio = 1.27) and improving survival (relative excess risk of death = 0.93) was no longer present in the multivariate model. Conclusion. Melanoma incidence, mortality, and survival vary in Italy according to latitude. After adjustment for several confounders, incidence still grows with growing latitude. Presumably, latitude expresses other variables that might be related to individual susceptibility and/or local care

Low Molecular Weight Protein-tyrosine Phosphatase Tyrosine Phosphorylation by c-Src during Platelet-derived Growth Factor-induced Mitogenesis Correlates with Its Subcellular Targeting

The low molecular weight phosphotyrosine phosphatase (LMW-PTP) is an enzyme that is involved in the early events of platelet-derived growth factor (PDGF) receptor signal transduction. Our previous results have shown that LMW-PTP is able to specifically bind and dephosphorylate activated PDGF receptor, thus modulating PDGF-induced mitogenesis. In particular LMW-PTP is involved in pathways that regulate the transcription of the immediately early genes myc and fos in response to growth factor stimulation. In this study we have established that, in nontransformed NIH3T3 cells, LMW-PTP exists constitutively in cytosolic and cytoskeleton-associated localization and that, after PDGF stimulation, c-Src is able to bind and to phosphorylate LMW-PTP only in the cytoskeleton-associated fraction. As a consequence of its tyrosine phosphorylation, LMW-PTP significantly increases its catalytic activity. After PDGF stimulation these two LMW-PTP pools act on distinct substrates, contributing in different manners to the PDGF receptor signaling. The cytoplasmic LMW-PTP fraction exerts its well known action on activated PDGF receptor. On the other hand we have now demonstrated that the cytoskeleton-associated LMW-PTP acts specifically on a few not yet identified proteins that become tyrosine-phosphorylated in response to the PDGF receptor activation. Finally, these two LMW-PTP pools markedly differ in the timing of the processes in which they are involved. The cytoplasmic LMW-PTP pool exerts its action within a few minutes from PDGF receptor activation (short term action), while tyrosine phosphorylation of cytoskeleton-associated LMW-PTP lasts for more than 40 min (long term action). In conclusion LMW-PTP is a striking example of an enzyme that exerts different functions and undergoes different regulation in consequence of its subcellular localization

The Molecular Basis of the Differing Kinetic Behavior of the Two Low Molecular Mass Phosphotyrosine Protein Phosphatase Isoforms

The low molecular mass phosphotyrosine protein phosphatase is a cytosolic enzyme of 18 kDa. Mammalian species contain a single gene that codifies for two distinct isoenzymes; they are produced through alternative splicing and thus differ only in the sequence from residue 40 to residue 73. Isoenzymes differ also in substrate specificity and in the sensitivity to activity modulators. In our study, we mutated a number of residues included in the alternative 40-73 sequence by substituting the residues present in the type 2 isoenzyme with those present in type 1 and subsequently examined the kinetic properties of the purified mutated proteins. The results enabled us to identify the molecular site that determines the kinetic characteristics of each isoform; the residue in position 50 plays the main role in the determination of substrate specificity, while the residues in both positions 49 and 50 are involved in the strong activation of the type 2 low M(r) phosphotyrosine protein phosphatase isoenzyme by purine compounds such as guanosine and cGMP. The sequence 49-50 is included in a loop whose N terminus is linked to the beta 2-strand and whose C terminus is linked to the alpha 2-helix; this loop is very near the active site pocket. Our findings suggest that this loop is involved both in the regulation of the enzyme activity and in the determination of the substrate specificity of the two low M(r) phosphotyrosine protein phosphatase isoenzymes

Molecular genetic features and risk assessment in a series of 30 patients who underwent an operation for gastrointestinal stromal tumours

Background: The objective of the study was to investigate the relationship between molecular genetic features and the standard criteria of risk assessment in patients affected by gastrointestinal stromal tumours (GISTs). Methods: A review was conducted of a series of 30 patients, with a mean age of 67 years, who underwent surgery for primary GISTs. R0 resection was accomplished in 27 patients. CD117, CD34 desmin, vimentin, S-100 and smooth muscle actin were immunohistochemically tested to achieve a diagnosis of GIST. The loss of wild-type KIT or platelet-derived growth factor receptor alpha (PDGFRα) genes was investigated by sequencing the tumour DNA. Results: Tumour genes mutations were reported in 23 patients (77%), and wild-type in seven. Mutations on the KIT gene occurred in 18 patients, and mutations on the PDGFRα gene in five. The average sizes of the GIST were 8.7 cm, 5.4 cm and 5.9 cm for KIT gene-mutated, PDGFRα gene-mutated and wild-type tumours, respectively. KIT gene mutations were detected in 50% of gastric and in 70% of extragastric GISTs. Moreover, 70% of tumours with a mitotic rate ≥ 5 x 50 highpower fields (HPFs) underwent KIT gene mutations. Conversely, PDGFRα mutations were observed only in gastric GISTs with a mitotic rate ≤ 5 x 50 HPFs. By stratifying GISTs according to classes of risk, KIT mutation was shown in most of the high-risk tumours. PDGFRα mutations occurred exclusively in lower classes of risk. Conclusion: Molecular analysis data might have a role as a prognostic variable in models of risk assessment for patients with GISTs

Identification of two distinct molecular subtypes by digital RNA counting of "non-invasive follicular tumour with papillary-like nuclear features (NIFTP)"

Backgound. The follicular variant (FV) is one of the most common variants of papillary thyroid carcinoma (PTC). Clinically, the FVPTC is considered a low-risk variant of PTC, and the encapsulated forms of FVPTC represent a group of thyroid tumours with an overall good prognosis. Consequently, these neoplasms were very recently reclassified as "non-invasive follicular tumour with papillary-like nuclear features (NIFTP)". From a molecular standpoint, NIFTP appears similar to the follicular pattern thyroid neoplasm; however, limited data are currently available regarding their gene expression profile

Mesenchymal to amoeboid transition is associated with stem-like features of melanoma cells

Background: Cellular plasticity confers cancer cells the ability to adapt to microenvironmental changes, a fundamental requirement for tumour progression and metastasis. The epithelial to mesenchymal transition (EMT) is a transcriptional programme associated with increased cell motility and stemness. Besides EMT, the mesenchymal to amoeboid transition (MAT) has been described during tumour progression but to date, little is known about its transcriptional control and involvement in stemness. The aim of this manuscript is to investigate (i) the transcriptional profile associated with the MAT programme and (ii) to study whether MAT acquisition in melanoma cancer cells correlates with clonogenic potential to promote tumour growth. Results: By using a multidisciplinary approach, we identified four different treatments able to induce MAT in melanoma cells: EphA2 overexpression, Rac1 functional inhibition using its RacN17 dominant negative mutant, stimulation with Ilomastat or treatment with the RhoA activator Calpeptin. First, gene expression profiling identified the transcriptional pathways associated with MAT, independently of the stimulus that induces the MAT programme. Notably, gene sets associated with the repression of mesenchymal traits, decrease in the secretion of extracellular matrix components as well as increase of cellular stemness positively correlate with MAT. Second, the link between MAT and stemness has been investigated in vitro by analysing stemness markers and clonogenic potential of melanoma cells undergoing MAT. Finally, the link between MAT inducing treatments and tumour initiating capability has been validated in vivo. Conclusion: Taken together, our results demonstrate that MAT programme in melanoma is characterised by increased stemness and clonogenic features of cancer cells, thus sustaining tumour progression. Furthermore, these data suggest that stemness is not an exclusive feature of cells undergoing EMT, but more generally is associated with an increase in cellular plasticity of cancer cells

The effects of CA IX catalysis products within tumor microenvironment

Solid tumors are composed of both cancer cells and various types of accessory cells, mainly fibroblasts, that collectively compose the so called tumor-microenvironment. Cancer-associated fibroblasts have been described to actively participate in cancer progression by establishing a cytokine-mediated as well as metabolic crosstalk with cancer cells. In the present paper we show that activated human fibroblasts are able to boost tumor cells proliferation and that this effect is greatly dependent on stromal carbonic anhydrase IX (CA IX) activity. In fact fibroblasts show a strong upregulation of CA IX expression upon activation by cancer cells, while CA IX products, protons and bicarbonate, exert differential effects on cancer cells proliferation. While acidification of extracellular pH, a typical condition of rapidly growing solid tumors, is detrimental for tumor cells proliferation, bicarbonate, through its organication, supplies cancer cells with intermediates useful to sustain their high proliferation rate. Here we propose a new kind of fibroblasts/tumor cells crosstalk within tumor microenvironment, mediated by stromal CA IX products, aimed to favor cancer cells growth, opening new perspectives on CA IX role in tumor microenvironment

The low Mr phosphotyrosine protein phosphatase behaves differently when phosphorylated at Tyr131 or Tyr132 by Src kinase

AbstractThe low molecular weight phosphotyrosine protein phosphatase (LMW-PTP) is phosphorylated by Src and Src-related kinases both in vitro and in vivo; in Jurkat cells, and in NIH-3T3 cells, it becomes tyrosine-phosphorylated upon stimulation by PDGF. In this study we show that pp60Src phosphorylates in vitro the enzyme at two tyrosine residues, Tyr131 and Tyr132, previously indicated as the main phosphorylation sites of the enzyme, whereas phosphorylation by the PDGF-R kinase is much less effective and not specific. The effects of LMW-PTP phosphorylation at each tyrosine residue were investigated by using Tyr131 and Tyr132 mutants. We found that the phosphorylation at either residue has differing effects on the enzyme behaviour: Tyr131 phosphorylation is followed by a strong (about 25-fold) increase of the enzyme specific activity, whereas phosphorylation at Tyr132 leads to Grb2 recruitment. These differing effects are discussed on the light of the enzyme structure