BRAFV600E and KIT immunoexpression in early-stage melanoma

Abstract: Melanoma is widely known as the most lethal skin cancer. Specific tumor-related mortality can be significantly reduced if diagnosis and treatment are properly performed during initial phases of the disease. The current search for biomarkers in early-stage melanomas is a high-priority challenge for physicians and researchers. We aimed to assess the immunoexpression of BRAFV600E and KIT in a case series consisting of 44 early-stage melanomas. Formalin-fixed paraffin-embedded samples were systematically evaluated using a semi-quantitative method based on scores of percentage and intensity for immunostained tumor cells. We observed significant concordance between BRAFV600E and KIT immunoexpression in thin invasive melanomas. Our findings corroborate previous evidence showing abnormal expression of proteins associated with MAPK intracellular signaling pathway in early-stage melanomas.

Indolamina 2, 3-dioxigenase (IDO) em melanoma: regulação frente ao inibidor de BRAF e sua expressão na progressão da doença / Indoleamine 2, 3-dioxygenase (IDO) in melanoma: regulation against BRAF inhibitor and its expression in disease progression

Os inibidores de BRAF (iBRAFs) e de MEK (iMEK), inauguraram uma nova classe de medicamentos, a terapia direcionada, no combate ao melanoma metastático. Entretanto, os pacientes adquirem resistência ao tratamento em poucos meses. Além disso, a imunoterapia vem ganhando espaço no tratamento do câncer, incluindo o melanoma, porém, com alguns aspectos inexplorados. Dentro deste tema, a enzima IDO vem despertando um grande interesse pela participação nos mecanismos de imunotolerância, imunoescape e progressão tumoral. A IDO é responsável pelo consumo e depleção do triptofano, produzindo a quinurenina. Ela está presente em diversos tipos celulares, incluindo células do sistema imune e células tumorais. Este trabalho objetivou avaliar a expressão de IDO durante a progressão da doença - desde do nevo até o melanoma metastático e também avaliar a regulação de IDO induzido por IFN-γ após tratamento com iBRAF em linhagens parentais e resistentes ao iBRAF, buscando-se os mecanismos moleculares. Por fim, objetivou-se entender os efeitos do 1-metil-triptofano (1-MT), um inibidor de IDO, tanto na sua capacidade de inibir a atividade de IDO quanto na sua influência na capacidade clonogênica. O estudo de bioinformática sobre o repositório público GSE12391 mostrou que o nível de expressão gênica de IDO foi superior nos estágios mais avançado da doença. Além disso, todas amostras de melanoma primário de pacientes apresentaram a imunomarcação de IDO, enquanto que nenhuma amostra de nevo apresentou tal marcação. Adicionalmente, a ocorrência de IDO se deu nos infiltrados linfoides, em células mononucleares do sistema imune. Duas análises de bioinformática de expressão gênica demonstraram que a IDO estava expressa positivamente na fase de resistência ao iBRAF. Ademais, os resultados de expressão proteica mostraram que a inibição de via MAPK (tanto por iBRAF quanto por iMEK) conseguiu modular a expressão de IDO, sendo que a maioria das linhagens apresentou uma diminuição de IDO. A atividade de IDO, medida através da produção de quinurenina, por HPLC se mostrou em consonância com os resultados de expressão proteica, exceto pela linhagem WM164 que não apresentou atividade enzimática, embora a proteína estivesse presente. Por fim, o 1-MT conseguiu inibir de maneira eficiente a enzima IDO, bloqueando a produção de quinurenina. Além de que, o 1-MT reduziu a capacidade clonogênica de maneira dose-dependente. Portanto, conclui-se que a expressão de IDO é crescente conforme a progressão do melanoma, que a inibição da via MAPK regulou a expressão de IDO e que o 1-MT reduz a capacidade clonogênica, além da sua função primária de inibir IDO

BRAF and MEK inhibitors (BRAFi and MEKi) has launched a new class of medication, the target therapy, to combat metastatic melanoma. Nevertheless, patients acquired resistance to the treatment in few months. Additionally, immunotherapy has been gaining space in cancer treatment, including melanoma, but some aspects need to be explored. Inside this theme, IDO enzyme has called the attention due to its participation in the mechanisms of immune tolerance, scape and tumor progression. IDO is responsible for tryptophan consume e depletion, producing kynurenine. It is present in different cells, including cells from immune system and tumor cells. This work purposed evaluate IDO expression during disease progression - since nevus until metastatic melanoma and also, evaluate IFN-γ-induced IDO regulation after BRAFi treatment in parental and resistant melanoma cell lines, seeking the molecular mechanisms. Lastly, it was evaluated the effects of 1-methyltryptopahn (1-MT), an IDO inhibitor, by its ability to inhibit IDO and also by its influency on the clonogenic capability. Bioinformatic study performed on GSE12391 showed that gene expression level of IDO was superior in the most advanced stages of the disease. Additionally, all sample of patient's primary melanoma presented IDO immunostaining, whereas, no nevus samples presented such staining. Besides, IDO occurrence was in the lymphoid infiltrates, in mononuclear cells from immune system. Two bioinformatic analysis of gene expression demonstrated that IDO was differentially overexpressed during BRAFi resistance stage. Moreover, protein expression results presented that MAPK pathway inhibition (both by BRAFi and by MEKy) was able to modulate IDO expression, and most of the cell lines presented an IDO downregulation. IDO activity, measured through kynurenine production, by HPLC was consonant with protein expression results, except by WM164 cell line, which did not present enzymatic activity, albeit the protein was present. By the end, 1-MT could inhibit efficiently IDO enzyme, blocking kynurenine production. Furthermore, 1-MT reduced clonogenic capability in a dosedependent manner. Therefore, it was concluded that IDO expression increases along with melanoma progression, MAPK pathway inhibition regulated IDO expression and 1-MT reduced clonogenic capability, besides its primary function of IDO inhibitor

Macelignan inhibits bee pathogenic fungi Ascophaera apis growth through HOG1 pathway

Ascosphaera apis is a bee pathogen that causes bee larvae infection disease, to which treatment is not yet well investigated. The aim of this study was to investigate antifungal susceptibility in vitro against A. apis and to identify a new antifungal agent for this pathogen through minimal inhibitory concentration (MIC) assay and western blot analysis. Macelignan had 1.56 and 3.125 μg/mL MIC against A. apis after 24 and 48 h, respectively, exhibiting the strongest growth inhibition against A. apis among the tested compounds (corosolic acid, dehydrocostus lactone, loganic acid, tracheloside, fangchinoline and emodin-8-O-β-D-glucopyranoside). Furthermore, macelignan showed a narrow-ranged spectrum against various fungal strains without any mammalian cell cytotoxicity. In spite of miconazole having powerful broad-ranged anti-fungal activity including A. apis, it demonstrated strong cytotoxicity. Therefore, even if macelignan alone was effective as an antifungal agent to treat A. apis, combined treatment with miconazole was more useful to overcome toxicity, drug resistance occurrence and cost effectiveness. Finally, HOG1 was revealed as a target molecule of macelignan in the anti-A. apis activity by inhibiting phosphorylation using S. cerevisiae as a model system. Based on our results, macelignan, a food-grade antimicrobial compound, would be an effective antifungal agent against A. apis infection in bees.

Involvement of mitogen-activated protein kinases and p21Waf1 in hydroxyurea-induced G1 arrest and senescence of McA-RH7777 rat hepatoma cell line

Hydroxyurea is commonly used to treat hematologic disorders and some type of solid tumors, but the mechanism for its therapeutic effect is not clearly known. In this study, we examined the effect of hydroxyurea on rat hepatoma McA-RH7777 cells, specifically, on the role of mitogen-activated protein (MAP) kinase signal transduction pathways and p21Waf1, p27Kip1 and p53. Rat hepatoma McA-RH7777 cells treated with hydroxyurea for 7 days, caused the inhibition of cell growth in a dose-dependent manner. But, this growth inhibition was not caused by necrosis or apoptosis but instead was associated with cell senescence-like change as evidenced by senescence associated-beta-galactosidase staining, and cells arrest at G1 phase of cell cycle. Phosphorylation of MAP kinases, such as ERK, JNK, and p38, was found to be decreased after treatment of cells with hydroxyurea. But, the expression of p21Waf1 was increased, while p27Kip1 and p53 were not detected in hydroxyurea treated rat hepatoma cells. Hydroxyurea treatment induced G1 arrest and a senescence-like changes in rat hepatoma McA-RH7777 cells may be the likely results of signal disruption of MAP kinases (ERK, JNK, and p38 MAP kinase) and p21Waf1 over-expression.

Molecular assembly of mitogen-activated protein kinase module in ras-transformed NIH3T3 cell line

The ras, is a G-like protein that controls the mitogen-activated protein kinase (MAPK) pathway involved in control and differentiation of cell growth. MAPK is a key component of its signaling pathway and the aberrant activation may play an important role in the transformation process. To better understand roles of ras in the activation of MAPKs, we have established ras transformed NIH3T3 fibroblast cell line, and analyzed the MAPK module. The ras transformed cells formed numerous spikes at the edges of cells and showed loss of contact inhibition. The levels of ERK1/2 MAPKs as revealed by Western blot analysis were not significantly different between ras transformed and non-transformed cells. However, phosphorylation of ERK MAPKs and the level of MEK were significantly increased although the heavily expressed level of Raf-1, an upstream component of MAPK pathway was unchanged in ras transformed NIH3T3 cells. The sedimentation profile of the MAPK module kinases in a glycerol gradient showed the presence of a rather homogeneous species of multimeric forms of ERK1/2 and MEK as indicated by the narrow distribution peak areas. The broad sedimentation profile of the Raf-1 in a glycerol gradient may suggest possible heterologous protein complexes but the identification of interacting molecules still remains to be identified in order to understand the organization of the MAPK signal transduction pathway.