Dynamic alteration of telomerase expression and its diagnostic significance in liver or peripheral blood for hepatocellular carcinoma

Circulating specific biomarkers in diagnosis of hepatocellular carcinoma and its metastasis monitoring

Hepatocellular carcinoma (HCC) is one of the most common and rapidly fatal malignancies worldwide with a multifactorial, multistep, complex process and poor prognosis. Its early diagnosis and metastasis monitoring are of the utmost importance. Hepatoma tissues synthesize various tumor-related proteins, genes, enzymes, microRNA, etc. and then secrete into the blood. Detections of circulating biomarkers are useful to find tumor at an early stage or monitor metastasis after postoperative treatment. This paper summarizes recent studies of specific biomarkers at early diagnosis or in monitoring metastasis or postoperative recurrence of HCC.

Recovering circulating extracellular or cell-free RNA from bodily fluids

The presence of extracellular circulating or cell-free RNA in biological fluids is becoming a promising diagnostic tool for non invasive and cost effective cancer detection. Extracellular RNA or miRNA as biological marker could be used either for the early detection and diagnosis of the disease or as a marker of recurrence patterns and surveillance. In this review article, we refer to the origin of the circulating extracellular RNA, we summarise the data on the biological fluids (serum/plasma, saliva, urine, cerebrospinal fluid and bronchial lavage fluid) of patients suffering from various types of malignancies reported to contain a substantial amount of circulating extracellular (or cell-free) RNAs and we discuss the appropriate reagents and methodologies needed to be employed in order to obtain RNA material of high quality and integrity for the majority of the experimental methods used in RNA expression analysis. Furthermore, we discuss the advantages and disadvantages of the RT-PCR or microarray methodology which are the methods more often employed in procedures of extracellular RNA analysis.

The regulation of telomerase in oncogenesis

The influence that the expression of the human (glial-derived neurotrophic factor (GDNF)) neurotrophic factor has on the morphology and proliferative activity of embryonic stem cells (SC) of a mouse with R1 lineage, as well as their ability to form embroid bodies (EB), has been studied. Before that, using a PCR (polymerase chain reaction) coupled with reverse transcription, it was shown that, in this very lineage of the embryonic SC, the expression of the receptors' genes is being fulfilled for the neurotropfic RET and GFRα1 glia factor. The mouse's embryonic SC lineage has been obtained, transfected by the human GDNF gene, and has been fused with the "green" fluorescent protein (GFP) gene. The presence of the expression of the human GDNF gene in the cells was shown by northern hybridization and the synthesis of its albuminous product by immunocitochemical coloration with the use of specific antibodies. The reliable slowing-down of the embriod-body formation by the embryonic SC transfected by the GDNF gene has been shown. No significant influence of the expression of the GDNF gene on the morphology and the proliferative activity of the transfected embryonic SCs has been found when compared with the control ones.

CpG island methylator phenotype association with upregulated telomerase activity in hepatocellular carcinoma

CpG island methylator phenotype (CIMP) involves the targeting of multiple genes by promoter hypermethylation. Telomerase plays an important role in the development of cellular immortality and oncogenesis. To gain insight into the role of epigenetic aberration of telomerase-related genes in hepatocarcinogenesis, we determined a hypermethylation profile in HCC. We examined the promoter methylation status of 9 genes associated with telomerase activity in 120 HCC, 120 cirrhosis tissues and 10 normal liver tissues by methylation-specific PCR. Assay of telomerase activity was by TRAP-ELISA. The frequency of promoter methylation of each gene was P21 63.3%, P15 42.5%, P16 62.5%, P53 14.2%, RB 32.5%, P27 48.3%, WTI 54.2%, E2F-1 70.8% and P300 65.8% of 120 HCC. Methylation status of P21, P15, P16, WTI and E2F-1 was significantly associated with HCC and nontumor tissues (p < 0.05). CIMP+ was detected in 61.7% (74/120) HCC and 15% (18/120) cirrhosis tissues, no CIMP+ was present in normal liver tissues (p < 0.001). A significant difference between CIMP status and metastasis was been found in HCC (p < 0.001). Results showed that 94.6% (70/74) HCC and 55.6% (10/18) cirrhosis patients with CIMP+ show expression of high telomerase activity than 45.5% (10/22) HCC and 6.25% (1/16) cirrhosis patients with CIMP- (p < 0.001). CIMP lead to high levels of expression of telomerase activity through the simultaneous inactivation of multiple genes associated with telomerase activity by concordant methylation.