RESUMO
Chemokines and their receptors have been shown to contribute to tumor growth and metastatic spread in various gastrointestinal cancer entities. In the present study, the mRNA expression profiles and clinical significance of chemokine ligand CXCL12 and its corresponding receptor CXCR4 were investigated in patients with gastric cancer (GC). Using quantitative polymerase chain reaction, the expression profile of CXCL12/CXCR4 was analyzed in resection specimens from the patients with GC (n=66) and in corresponding normal gastric tissues. Upon investigating CXCL12/CXCR4 mRNA expression levels in the GC tissues, significant downregulation of CXCL12 expression was demonstrated (P<0.05), whereas CXCR4 mRNA expression was shown to be significantly upregulated (P<0.05). Likewise, in gastric carcinoma patients undergoing neoadjuvant chemotherapy, CXCR4 expression was found to be significantly upregulated (P<0.05), whereas in GC patients with lymph and vein infiltration, CXCL12 mRNA expression was significantly downregulated (P<0.05). These results demonstrate a significant inverse association between the development and progress of GC and CXCL12/CXCR4 mRNA expression. CXCR4 mRNA upregulation was promoted under the effect of neoadjuvant chemotherapy prior to surgery in GC patients, whereas higher tumor stages with lymph and vein infiltration negatively affected CXCL12 mRNA expression.
RESUMO
Humans and primates are long-lived animals with long reproductive phases. One factor that appears to contribute to longevity and fertility in humans, as well as to cancer-free survival, is the transcription factor and tumor suppressor p53, controlled by its main negative regulator MDM2. However, p53 and MDM2 homologs are found throughout the metazoan kingdom from Trichoplacidae to Hominidae. Therefore the question arises, if p53/MDM2 contributes to the shaping of primate features, then through which mechanisms. Previous findings have indicated that the appearances of novel p53-regulated genes and wild-type p53 variants during primate evolution are important in this context. Here, we report on another mechanism of potential relevance. Human endogenous retrovirus K subgroup HML-2 (HERV-K(HML-2)) type 1 proviral sequences were formed in the genomes of the predecessors of contemporary Hominoidea and can be identified in the genomes of Nomascus leucogenys (gibbon) up to Homo sapiens. We previously reported on an alternative splicing event in HERV-K(HML-2) type 1 proviruses that can give rise to nuclear protein of 9 kDa (Np9). We document here the evolution of Np9-coding capacity in human, chimpanzee and gorilla, and show that the C-terminal half of Np9 binds directly to MDM2, through a domain of MDM2 that is known to be contacted by various cellular proteins in response to stress. Np9 can inhibit the MDM2 ubiquitin ligase activity toward p53 in the cell nucleus, and can support the transactivation of genes by p53. Our findings point to the possibility that endogenous retrovirus protein Np9 contributes to the regulation of the p53-MDM2 pathway specifically in humans, chimpanzees and gorillas.
Assuntos
Produtos do Gene env/fisiologia , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Animais , Sequência de Bases , Linhagem Celular Tumoral , Evolução Molecular , Gorilla gorilla/genética , Humanos , Pan troglodytes/genética , Ligação Proteica , Homologia de Sequência do Ácido Nucleico , Proteína Supressora de Tumor p14ARF/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
BACKGROUND: Recently, involvement of the chemokine/receptor system CCL20/CCR6 in colorectal cancer (CRC) progression was shown. Here, we analyzed the functional interaction of miRNA-518-5p (miR-518a-5p) with CCR6 and its impact on CCR6 expression in CRC cells. METHODS: MiR-518a-5p was identified by computer software to potentially interact with CCR6. Hence, functional implications of miR-518a-5p with the 3'UTR of CCR6 were analyzed using the Dual Luciferase Reporter assay system. Confirmation of the predicted target site for miR-518a-5p was achieved by site-directed mutagenesis of the seed sequence in the 3'UTR of CCR6 and subsequent application of the mutated seed sequence in a luciferase assay with miR-518a-5p mimics. Accordingly, two CRC cell lines (Caco-2 and HT-29) were transfected with miR-518a-5p miRNA mimics and gene and protein expression of CCR6 was monitored using qRT PCR and immunocytochemistry, respectively. RESULTS: Addition of miR-518a-5p led to significant down-regulation of luciferase activity (P < 0.05), which was significantly reversed in a reporter test system containing the mutated seed sequences in the 3'UTR of CCR6. Following transfection of CRC cell lines with miR-518a-5p mimics and subsequent monitoring of CCR6 expression showed significant down-regulation of CCR6 mRNA and CCR6 protein expression in both CRC cell lines under investigation (P < 0.05). CONCLUSIONS: We have shown that miR-518a-5p functionally interacts with CCR6 and that transfection of CRC cells with miR-518a-5p leads to significant CCR6 down-regulation. Consequently, CCR6 expression is regulated by miR-518a-5p in CRC cells indicating that regulation of CCR6 expression by miR-518a-5p might be a regulatory mechanism involved in CRC pathogenesis.
Assuntos
Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/metabolismo , Receptores CCR6/genética , Regiões 3' não Traduzidas/genética , Sequência de Bases , Linhagem Celular Tumoral , Regulação para Baixo/genética , Genes Reporter , Humanos , Luciferases/metabolismo , MicroRNAs/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação/genética , Ligação Proteica/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores CCR6/metabolismo , TransfecçãoRESUMO
Recently, we reported a functional interaction between miR-21 and its identified chemokine target CCL20 in colorectal cancer (CRC) cell lines. Here, we investigated whether such functional interactions are permitted at the cellular level which would require an inverse correlation of expression and also co-expression of miR-21 and CCL20 in the same cell. Expression profiling was performed using qPCR, and ELISA, in situ hybridization and immunohistochemistry were applied for the presentation of their cellular localization. We demonstrated that miR-21 as well as CCL20 were both significantly upregulated in CRC tissues; thus, showing no antidromic expression pattern. This provided an initial clue that miR-21 and CCL20 may not be expressed in the same cell. In addition, we located miR-21 expression at the cellular level predominantly in stromal cells such as tumor-associated fibroblasts and to a minor degree in immune cells such as macrophages and lymphocytes. Likewise, CCL20 expression was primarily detected in tumor-infiltrating immune cells. Thus, investigating the cellular localization of miR-21 and its target CCL20 revealed that both molecules are expressed predominantly in the microenvironment of CRC tumors.