LRIG1 is a positive prognostic marker in Merkel cell carcinoma and Merkel cell carcinoma expresses epithelial stem cell markers.

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine malignancy of the skin. The cell of origin of MCC is thus far unknown and proposed cells of origin include Merkel cells, pro-/pre- or pre-B cells, epithelial stem cells, and dermal stem cells. In this study, we aimed to shed further light on the possibility that a subset of MCC tumors arise from epithelial stem cells of the skin by examining the expression of hair follicle and epidermal stem cell markers in MCC and normal human skin. We also aimed to elucidate any correlation between the expression of these markers and tumor Merkel cell polyomavirus (MCPyV) status or other clinicopathological characteristics or patient survival. Expression of CK19, SOX9, LGR5, and LRIG1 in MCC and normal human skin was studied by immunohistochemistry, and the staining patterns or intensities were statistically correlated with patient, tumor, MCPyV, and survival parameters. In a cohort of 137 cases of MCC, we observed dot-like immunoexpression of CK19 in 30 cases (22.1%) and homogeneous expression in 103 cases (75.7%). We also observed positive immunoexpression of SOX9 in 21 cases (15.3%), LGR5 in 118 cases (86.1%), and LRIG1 in 117 cases (86.0%). Immunoexpression of LRIG1 was found to correlate with better overall and MCC-specific survival. We observed frequent immunoexpression of several hair follicle and epidermal stem cell markers in MCC and found LRIG1 to be a positive prognostic marker in MCC.

A novel MPLKIP-variant in three Finnish patients with non-photosensitive trichothiodystrophy type 4.

Trichothiodystrophy is a group of multisystem neuroectodermal disorders with dysplastic hair as the cardinal symptom. We describe three patients from two Finnish families in whom whole-exome sequencing revealed a novel homozygous variant, c.26del, p.(Pro9Glnfs*144) in the MPLKIP-gene, confirming the diagnosis of non-photosensitive trichothiodystrophy type 4 (TTD4). The variant was confirmed by Sanger sequencing and inherited from unaffected carrier parents. This report adds to the literature by expanding the genetic and phenotypic spectra of MPLKIP-related trichothiodystrophy. We describe dysmorphic features in the patients and provide a comparison of clinical characteristics in patients with TTD4 reported to date.

FGF-2 blocks TGF-beta1-mediated suppression of Bcl-2 in normal melanocytes.

Normal melanocytes require growth support provided by the adjacent basement membrane. In contrast, nevus cells and melanoma cells survive in the dermis, and in vitro on a soft collagen gel. Transforming growth factor-beta1 (TGF-beta1) produced by melanocytes themselves induces apoptosis in normal melanocytes cultured on collagen gel, an effect that can be counteracted by fibroblast growth factor-2 (FGF-2). The purpose of this study was to investigate the mechanisms by which FGF-2 counteracts the apoptotic signals from TGF-beta1 in melanocytes cultured on collagen gel. We report that FGF-2 did not interfere with the signal transduction from the TGF-beta1 receptors to SMAD2/3 proteins. Instead, TGF-beta1 decreased the level of Bcl-2 in normal melanocytes cultured on collagen gel, and FGF-2 reversed the TGF-beta1-mediated reduction in the level of Bcl-2. In nevus and melanoma cells, TGF-beta1 was unable to induce a decrease in the level of Bcl-2, and treatment with FGF-2 did not cause an increase in the level of Bcl-2 in nevus or melanoma cells. In conclusion, our results suggest that a reduction in the level of the anti-apoptotic Bcl-2 is involved in the execution of apoptosis induced by TGF-beta1 in normal melanocytes cultured on collagen gel and that FGF-2 can prevent TGF-beta1 from causing this reduction.

T-cell signal transduction in children with cow's milk allergy -- increased MAP kinase activation in patients with acute symptoms of cow's milk allergy.

The precise immune mechanisms behind cow's milk allergy (CMA) are still unknown. Previously, the production of the cytokines TNF-alpha and IFN-gamma in T cells from children with CMA has been shown to be decreased, and the production of IL-4 has been shown to be increased when compared to healthy children. As these aberrations in cytokine production may be associated with disturbances in cellular function, we investigated whether T-cell signal transduction is abnormal in children with CMA. For this purpose we evaluated the activation of the MAP kinase Erk2. Thirty-nine infants were included in the study. Of those with CMA, 13 had acute symptoms and 9 were free of symptoms due to a successful elimination diet at the time of the study. To activate T cells and to stimulate MAP kinase phosphorylation, peripheral blood mononuclear cells (PBMC) were incubated with Concanavalin A (ConA). The change in MAP kinase phosphorylation was measured by Western blotting. The increase in MAP kinase phosphorylation after stimulation with ConA for 5 min was significantly higher in cells from patients with acute symptoms of CMA than in cells from CMA patients free of symptoms or cells from healthy children. A time-course experiment showed that the change in MAP kinase phosphorylation was still increasing after 10 min incubation in cells from patients with acute symptoms of CMA. The increased MAP kinase activation was found to correlate positively with non-IgE mediated CMA in patients with acute symptoms of CMA.

The tyrphostin AG1024 accelerates the degradation of phosphorylated forms of retinoblastoma protein (pRb) and restores pRb tumor suppressive function in melanoma cells.

Constitutive cell surface receptor kinase signaling and persistent phosphorylation/inactivation of the retinoblastoma (pRb) family of proteins (pRb, p107 and p130, known as pocket proteins) have been implicated in conferring uncontrolled growth to melanoma cells. However, the signals linking receptor kinase activity to neutralization of pocket proteins have not yet been fully elucidated. We therefore used specific chemical inhibitors to examine pRb regulation in melanoma cells. The most efficient agent, AG1024, known as an inhibitor of insulin-like growth factor 1 receptor and insulin receptor, arrested melanoma cell growth in vitro at nanomolar concentrations within 24 h of application. AG1024 inhibited the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway and restored pRb tumor suppressive function. The latter was observed by the reduction in the phosphorylated forms of pRb, p107 and p130, and the formation of growth suppressive DNA binding complexes consisting of pRb and E2F1 or E2F3. The loss of phosphorylated forms of pRb at early time points after AG1024 application was not associated with suppression of cyclin-dependent kinases 2 and 4 activity but rather with proteasomal and nonproteasomal degradation. Thus, inhibition of melanoma cell proliferation by AG1024 is mediated by inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase 2 signaling and activation of pRb by a mechanism involving protein degradation.