الفهرس 
CoverOnly 14 pages are availabe for public view
 |  | from | 123 |  |  |
| | | from | 123 | | |
Abstract
Hepatitis C virus (HCV) represents a major public health problem, affecting 3% of the world’s population. Egypt has the highest worldwide prevalence of HCV affecting approximately 17-26% of the general population.
In majority of HCV infected patients (70-80%), HCV can effectively evade innate immunity resulting in chronic hepatitis, which can progress to cirrhosis and hepatocellular carcinoma (HCC).
Persistent infection with HCV is considered to be a prominent risk factor for the development of HCC. Although a strong relationship between HCV-induced chronic liver diseases and the development of HCC is widely accepted, the molecular mechanism of HCV-induced hepatocarcinogenesis is not clearly understood.
HCC is one of the most common primary malignant tumors of the liver and one of the major causes of morbidity due to liver cirrhosis consequences. Similar to most solid tumors, HCCs are believed to contain poorly differentiated cancer stem cell-like cells (CSCs) that initiate tumorigenesis and confer resistance to chemotherapy.
Several cell surface markers have been reported for identification and characterization of hepatic CSCs. Various studies showed that co-expression of CD44 and CD133 in HCC cells represented more precise stem cell properties of CSCs, including accelerated self-renewal, differentiation, and developing aggressive proliferation.
Recent study showed correlation of CD133+CD44+ HCC, characterized by higher proliferating properties and greater ability to induce tumor formation, with advanced tumor stages, poor survival, and tumor recurrence. Regarding the role of CD133 and CD44 in initiation and progression of HCC, it also has stem cell like properties, like colony-forming ability and differentiation potential.
The interaction of the stem cell with specific microenvironmental elements is thought to be a key regulatory mechanism in maintenance of its self-renewal and differentiation capacities. Additionally, it is clear that the tumor microenvironment plays a major role in HCC initiation and progression.
Matrix metalloproteinases (MMPs) are a diverse family of enzymes capable of specific degradation of various components of the ECM. Expression of various MMPs has been found to be up-regulated in, virtually, all types of primary human cancers, with circulating concentrations correlative with advanced stages of tumorgenesis, invasive and metastatic properties and, in general, poor prognosis.
HCV is known to affect the regulation of MMP activity in chronic hepatitis C infections and evolved an ability to modulate these proteases, presumably for providing a survival advantage. However, the role of HCV infections in promoting the expression of potential cancer stem cell markers and its role to initiate tumor growth is poorly targeted and needs practical clarification. In addition, modulation of MMP2 serum levels by HCV infections is an active area of research in the field of tumor management.
Therefore, the present work attempted to study the mRNA expression of cancer stem cell markers CD133 and CD44 (reflecting alterations in CSCs population) as well as serum levels of matrix metalloproteinase-2 (reflecting modifications in ECM pathophysiology) in patients with chronic hepatitis C virus (reflecting the role of HCV) and their correlation with progression to HCC.
For this purpose, peripheral blood mononuclear cell (PBMC) prepared from chronic HCV patients (either with or without complications) were probed for mRNA expression of CD133 and CD44 by RT-PCR and compared to that of non-HCV cirrhotic patients as well as healthy controls. In addition, MMP-2 levels were measured using a standardized ELISA technique in sera of all subjects under study as well as in selected ascetic fluids from HCV patients with cirrhosis and HCC.
Concerning hematological and liver function data, the results of the present study revealed that platelet counts were reduced in all patient groups relative to healthy individuals; but were lower than the globally accepted reference range only in HCV patients with end stage complications (HCC and cirrhosis). These results were associated with parallel impairment in serum albumin level and prothrombin activity while total serum bilirubin and SGPT were elevated in a manner consistent with that observed in platelet counts.
Concerning CD133 mRNA in PBMCs, maximal expression was recorded in HCV patients with no complications; where no significant difference between patients with cirrhosis and HCC was noticed. Meanwhile, minimal expression was registered in non-HCV cirrhotic patients. On the other hand, maximal CD44 mRNA expression was noticed in PBMCs of HCC patients that were even significantly higher than their HCV cirrhotic partners and, interestingly, in chronic HCV patients than cirrhotics and controls. Again, minimal expression was observed in non-HCV cirrhotic subjects. Interestingly, identical statistical profile was encountered when analyzing data of the circulating MMP-2 levels except that significant elevation in MMP-2 was recorded in all patient groups as compared to healthy controls. The maximal elevation in the level of MMP-2 was noticed in HCV patients with HCC. Also the concentrations of MMP-2 in ascetic fluid of cirrhotic patients gave almost similar figures to that found in sera while in patients with HCC there was a 2.4 times elevation in serum levels of MMP-2 as compared to that in ascetic fluids. Interestingly, ascetic fluid MMP-2 levels in cirrhotic patients showed 1.8 times increase than patients with HCC.
Concerning correlation analysis, albumin was positively correlated with prothrombin activity and platelet counts but negatively correlated with total bilirubin and SGPT (both were positively correlated with each other but negatively correlated with platelet counts and prothrombin activity). The last two parameters were always positively correlated to each other.
Correlation studies revealed also that MMP2 levels were positively correlated with CD133, CD44, total bilirubin and SGPT while showed negative correlation with platelet counts, prothrombin activity and albumin. There was also positive correlation between CD44 and CD133 while the former was negatively correlated with albumin and prothrombin activity and CD44 showed positive correlation with SGPT.
These findings highlight the important role induced by HCV infection in breakage of signaling network for normal stem cells leading to transformation into CSCs. In addition HCV has important role in increasing level of MMP-2 where it can influence on stem cell by obliging them to modify their phenotype in order to survive, thus increasing the invasion potential and facilitate tumor progression.