Telomerase activity in human liver tissues: comparison between chronic liver disease and hepatocellular carcinomas.

Telomerase activity was examined in 105 frozen samples from human normal liver tissues, chronic liver disease, and hepatocellular carcinoma (HCC). Telomerase activity was positive in 28 of 33 HCC tissues regardless of tumor stage or size. Telomerase was expressed in 15 of 18 differentiated HCC nodules smaller than 3 cm. HCC tissues from all eight hepatitis B virus-positive patients were telomerase positive, while telomerase activity was not detected in normal liver tissues (0 of 4). Weak telomerase activity was only detected in 1 of 22 nontumor liver tissues from HCC patients. Interestingly, in 19 of 38 hepatitis tissues and 6 of 8 cirrhotic liver tissues from apparently cancer-free patients, very weak telomerase activity was detected. These results indicate that the expression of telomerase may play a crucial role in hepatocarcinogenesis.

Alteration of telomeric repeat length in hepatocellular carcinoma is independent of telomerase activity.

Length of terminal restriction fragments (TRFs) was examined in 34 samples from hepatocellular carcinoma (HCC) patients. TRF length alterations (reduction or elongation) were found in 18 of 34 (53%) HCC nodules (13 cases reduced, 5 cases elongated). The incidence of TRF alteration was significantly higher in HCC exceeding 3 cm in diameter, moderately- or poorly-differentiated in histology, or with microscopic aggressive lesions (P<0.05). The survival rates were significantly higher in patients without alterations in TRFs (P<0.05). Specifically, all 5 cases with elongated TRFs recurred within 1 year after resection and had a poor prognosis. In contrast, the presence of telomerase activity was not associated with alterations in TRF length. The incidence of TRF length alterations increased with HCC tumor progression.

Telomerase in hepatocellular carcinogenesis.

Despite the recent advances in diagnostic techniques of HCC, diagnosis of HCC is still difficult and ambiguous when HCC is small and of the well differentiated type. The results presented here demonstrated that strong telomerase activity was frequently detected in HCC irrespective of the stage or size of the nodules but neither in non-tumor diseased liver nor in normal liver. Telomerase activity determination can be a useful additional tool for the diagnosis of early well-differentiated HCC.

[Telomere length and telomerase activity in hepatocellular carcinoma].

Telomerase activity and terminal restriction fragment (TRF) length were examined in hepatocellular carcinoma (HCC). Telomerase activity was assayed by telomeric repeat amplification protocol (TRAP) connected with an internal telomerase assay standard (ITAS). The incidence of strong telomerase activity (highly variable level compared with the activity of non-cancerous liver tissue) was 79% in well, 84% in moderately, and 100% in poorly differentiated HCC, while 0% in non-cancerous liver tissues. The incidence of TRF length alteration (reduction or elongation) was 53% in HCC. The incidence of TRF alteration was significantly higher in HCC exceeding 3 cm in diameter, moderately or poorly differentiated in histology. Telomerase activity was not associated with TRF length alteration in HCC. In conclusion, strong telomerase activity and TRF length alteration increased with HCC tumor progressions.

Significance of telomerase activity in the diagnosis of small differentiated hepatocellular carcinoma.

Precise diagnosis of well-differentiated hepatocellular carcinoma (HCC) is sometimes difficult to establish. Telomerase activity was examined by telomeric-repeat-amplification protocol (TRAP) in 37 HCC nodules smaller than 3 cm in diameter, including 24 fine-needle-aspiration biopsy specimens, 22 non-tumor chronic-liver-disease tissues (9 chronic hepatitis and 13 liver cirrhosis) and 3 normal liver tissues. Telomerase activity was assayed by serially diluted samples and quantitated by using an internal telomerase assay standard (ITAS). Telomerase activity was detected in all HCC and in 11 of 22 non-tumor chronic-liver-disease tissues. Normal liver samples had undetectable telomerase activity. Cut-off level of telomerase activity for its practical usage in HCC diagnosis was tentatively set for 0.6 microg liver protein/assay at 10-cell equivalent activity of a gastric-cancer cell line, MKN-1. This level was twice the highest activity in non-tumor chronic liver disease therefore, telomerase activity in all non-tumor liver samples was below this level. The telomerase-positive incidence exceeding this cut-off level was 73% (11/15) in well-differentiated HCC, 94% (16/17) in moderately differentiated HCC and 100% (5/5) in poorly differentiated HCC. Well-differentiated HCC showed low positivity by other diagnostic markers. 21% by AFP, 0% by PIVKA-II and 13% by angiography. The detection of telomerase activity may thus be a useful additional tool for precise and early diagnosis of small differentiated HCC, even when diagnosis is inconclusive by conventional techniques.

The assessment of proliferating cell nuclear antigen immunohistochemical staining in small hepatocellular carcinoma and its relationship to histologic characteristics and prognosis.

BACKGROUND: A precise prognostic factor for small hepatocellular carcinoma (HCC), the diagnosis of which recently has increased in incidence because of the development of diagnostic imaging techniques, is desirable. It has been reported that proliferating cell nuclear antigen (PCNA) would be related to proliferating cells, and thus the PCNA labeling index may provide useful information about the biologic behavior of small HCC. METHODS: An assessment was made of proliferative activity by immunohistochemical staining using a monoclonal antibody against PCNA in 46 nodules of HCC less than 3 cm in diameter resected from 44 patients. A correlation between PCNA labeling index and clinicopathologic findings or prognosis was sought. RESULTS: The mean labeling index was 18.7% in HCC and 1.9% in nontumor liver tissue. The labeling index corresponded to the degree of histologic differentiation, and the labeling index of well differentiated HCC was significantly lower (P < 0.05) than that of moderately or poorly differentiated HCC. The incidence of capsule formation in the high labeling index group (labeling index > or = 20%) was significantly higher (P < 0.05) than that in the low labeling index group (labeling index < 20%). A high incidence of capsular and vascular invasion was found in the high labeling index group. The survival rate after resection was significantly higher (P < 0.05) and the recurrence rate significantly lower (P < 0.05) in the low labeling index group than in the high labeling index group. CONCLUSIONS: The PCNA labeling index was shown to be closely related to histologic characteristics, and proved to be a useful indicator of recurrence and survival in small HCC.