👤 Hilda Samimi

Merkel cell carcinoma (MCC) is an aggressive malignant neuroendocrine tumour. There are two subsets of MCC, one related to Merkel cell polyomavirus (MCPyV) and the other to ultraviolet radiation (UVR). MCPyV-positive and MCPyV-negative MCCs have been considered to be different tumours, as the former harbour few DNA mutations and are not related to UVR, and the latter usually arise in sun-exposed areas and may be found in conjunction with other keratinocytic tumours, mostly squamous cell carcinomas. Two viral oncoproteins, large T antigen (LT; coded by MCPyV_gp3) and small T antigen (sT; coded by MCPyV_gp4), promote different carcinogenic pathways. To determine which genes are differentially expressed in MCPyV-positive and MCPyV-negative MCC; to describe the mutational burden and the most frequently mutated genes in both MCC subtypes; and to identify the clinical and molecular factors that may be related to patient survival. Ninety-two patients with a diagnosis of MCC were identified from the medical databases of participating centres. To study gene expression, a customized panel of 172 genes was developed. Gene expression profiling was performed with nCounter technology. For mutational studies, a customized panel of 26 genes was designed. Somatic single nucleotide variants (SNVs) were identified following the GATK Best Practices workflow for somatic mutations. The expression of LT enabled the series to be divided into two groups (LT positive, n = 55; LT negative, n = 37). Genes differentially expressed in LT-negative patients were related to epithelial differentiation, especially SOX9, or proliferation and the cell cycle (MYC, CDK6), among others. Congruently, LT displayed lower expression in SOX9-positive patients, and differentially expressed genes in SOX9-positive patients were related to epithelial/squamous differentiation. In LT-positive patients, the mean SNV frequency was 4.3; in LT-negative patients it was 10 (P = 0.03). On multivariate survival analysis, the expression of SNAI1 [hazard ratio (HR) 1.046, 95% confidence interval (CI) 1.007-1.086; P = 0.02] and CDK6 (HR 1.049, 95% CI 1.020-1.080; P = 0.001) were identified as risk factors. Tumours with weak LT expression tend to co-express genes related to squamous differentiation and the cell cycle, and to have a higher mutational burden. These findings are congruent with those of earlier studies. Show less

Anaplastic thyroid carcinoma (ATC) is the most lethal malignancy in thyroid carcinomas. Long non-coding RNAs (lncRNAs) are a member of non-coding RNAs, regulating the expression of gene. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is an onco-lncRNA that is overexpressed in several carcinomas including ATC. Evidence showed that MALAT1 has a crucial function in apoptosis, and cell cycle progression. In order to take advantage of 3D cell culture system in cancer investigation, we have used a 3D in vitro ATC model to determine the effect of dual MEK/Aurora kinase inhibitor BI-847325 anticancer drug on the fundamental molecular mechanisms of MALAT1-mediated gene regulation in ATC. In this study, ATC cell lines (C643 and SW1736) were grown in alginate scaffold. Encapsulated cells were treated by BI-847325. Changes in expression of MALAT1, Mcl1, miR-363-3p, and cyclinD1 were measured by qRT-PCR. MALAT1 gene expression following BI-847325 treatment was significantly downregulated in C643 and SW1736 cell lines. Reversely, miR-363-3p expression was significantly upregulated by BI-847325 in both ATC cell lines. Mcl1 expression was significantly downregulated after treatment in C643 cell lines. Moreover, the expression of this gene was not significantly reduced following BI-847325 treatment in SW1736 cell line. Additionally, cyclin D1 expression was significantly downregulated after treatment in both ATC cell lines. Altogether, the result of this study was the first report of MALAT1's molecular function in ATC and suggested that BI-847325 which inhibits both MEK and Aurora kinase family could be effective against ATC by regulating the genes involved in cell cycle and apoptosis including MALAT1and its downstream genes. Graphical abstract Schematic representation of the biological role of MALAT1 in cyclin D1, miR-363-3p and Mcl1 gene regulations. Stimulation of receptor tyrosine kinase (RTK) by growth factors (GFs) phosphorylates RAS that subsequently activates RAF. Then, RAF phosphorylates MEK. Consequently, activated MEK phosphorylates ERK downstream effector, leading to the MALAT1 gene expression. MALAT1 is a negative regulator of Mcl1 mRNA by sponging of miR-363-3p. In addition, MALAT1 leads to Axin1 and APC downregulation and Wnt/β-catenin signaling pathway activation. Stable β-catenin translocates from the cytoplasm to the nucleus and promotes cyclin D1 gene expression. Show less