الفهرس | Only 14 pages are availabe for public view |
Abstract Hepatocellular carcinoma (HCC) is a global health problem, with over 700,000 new cases worldwide each year. The prognosis of HCC patients remains poor. In Egypt, HCC accounts for about 4.7 of chronic liver disease patients. Thus, it is necessary to search for markers that can be used in early screening or prognosis in an attempt to improve the clinical management of HCC patients. The mitogen-activated protein kinase (MAPK) pathway is one of the pathways that are commonly activated in cancer. Dualspecificity protein kinase (DUSP) phosphorylates tyrosine and threonine residues in a TXY motif of MAPK, leading to full MAPK activation. MAPK phosphatase-7 (MKP7) or (DUSP16) was identified as a JNK-specific phosphatase. However, despite its high specificity for JNK, MKP7 interacts also with ERK. There are three JNK-coding genes have been identified in mammals: JNK1, JNK2, and JNK3. JNK3 is selectively expressed in neuronal tissues while JNK1 and JNK2 are ubiquitously expressed. JNK has been widely implicated in some physiological processes, including embryonic development, cell survival/apoptosis, and proliferation and production of inflammatory cytokines. Recently some studies found a relation between the miRNA regulation and some MAPK activity. For example, the upregulations of mir-24 inhibit DUSP16 (MKP7), which activates downstream signaling of JNK and alters myeloid cells and differentiation. Abnormal MAPK signaling has important consequences on the development and progression of human cancer. The objective of the present study was to understand the role of some miRNAs in the regulation of MAPK pathway in HCC of Egyptian patients; this achieved through: 1) Detection of the expression level of miRNAs targeting DUSP16 (MKP7) and JNK family (JNK1, JNK2, and JNK3) using quantitative Real-Time PCR (qRT-PCR) technique. 2) Detection of the protein levels of DUSP16, JNK1 and JNK2 using immunohistochemistry (IHC) assay. 3) To find a correlation between specific miRNAs and HCC cases. 4) Determination of specific miRNA that could be used as diagnostic markers for HCC patients. A highly significant downregulation was identified in JNK2 and JNK3 gene expression in HCC patients as compared to controls with (P value = 0.016, 0.000) respectively, on the other hand, there is no significant change was detected in DUSP16 and JNK1 gene expression. A strong positive correlation was recorded between the mRNA expression of DUSP16 and each of JNK1, JNK2, and JNK3 genes (P value less than 0.001) for each. In addition, we found 10 miRNAs, miR-18b; miR-30c; miR-30e; miR-99a; miR-126; miR- 194; miR-198; miR-215; miR-455 and miR-455-3p showed significant correlation with mRNA genes of DUSP16, JNK1, JNK2 and JNK3 (P value less than 0.05). Absence of protein expression was detected for DUSP16, JNK1, and JNK2 in all normal tissue samples. Whereas in HCC cases, 34% (13 out 38) showed DUSP16 protein expression (P ≤ 0.0001). 82% (31 out 38) for JNK1 (P ≤0.0001) and 71% (27 out 38) showed JNK2 protein expression (P ≤ 0.0001) which are statistically strong significant between cases and controls. These results provide a resource for studying the role of miRNAs in HCC patients and contribute to a better understanding of the physiological significance of miRNAs in the regulation of MAPK pathway. The miRNAs considered as a novel class of biomarkers because they have a specific signature with the disease. The high mortality rate of HCC is because the detection at late stage and limited therapeutic options. The clinical heterogeneity of HCC and the deficiency of good diagnostic markers and treatment strategies have condensed the disease a major challenge. And the MAPK gene and protein expression also play an important role in HCC as a therapeutic agent regulated by miRNAs. |