Sensitive and specific detection of circulating cancer cells in patients with hepatocellular carcinoma; detection of human telomerase reverse transcriptase messenger RNA after immunomagnetic separation.

PURPOSE: We evaluated whether detection of human telomerase reverse transcriptase (hTERT) mRNA after immunomagnetic separation is useful to detect circulating cancer (CC) cells. EXPERIMENTAL DESIGN: Two ml of peripheral blood were collected from 55 cases with hepatocellular carcinoma (HCC), 20 cases with chronic liver diseases devoid of cancer, and 20 healthy volunteers. Then 1500 and 500 micro l were subjected to immunomagnetic separations using Ber-EP4 and anti-CD45 antibodies, harvested and supernatant cells were collected as epithelial and nonleukocyte fractions, respectively. Samples of each fraction were subjected to reverse transcription-PCR detecting beta-actin, interleukin-2 receptor (IL-2r), alpha-fetoprotein, and hTERT mRNAs. The cases were judged to be positive, equivocal, or negative for CC cells when hTERT positivity with IL-2r negativity, hTERT positivity with IL-2r positivity, or hTERT negativity was seen in epithelial and/or nonleukocyte fractions, respectively. RESULTS: The dilution experiments revealed that our system could detect 10(0-1) HeLa cells involved in 2 ml of blood. The Ber-EP4-harvested cells from cases with distant metastasis were positive for immunostaining using Hep Par 1 monoclonal antibody. CC cells were judged to be positive in 29 of 55 (53%) HCC cases. On the contrary, no cases without HCC were determined to be positive. The frequency of positivity was significantly correlated with disease extent of HCC. CONCLUSIONS: These results strongly suggest that detection of hTERT mRNA after immunomagnetic separation is a specific and sensitive tool to detect CC cells and that it would provide useful source for further investigation of cancer metastasis.

Interferon can block telomere erosion and in rare cases result in hepatocellular carcinoma development with telomeric repeat binding factor 1 overexpression in chronic hepatitis C.

PURPOSE: The purpose of this study was to evaluate whether IFN therapy for chronic hepatitis C could overcome telomere reduction in the liver, a possible risk factor for hepatocellular carcinoma (HCC) development. EXPERIMENTAL DESIGN: Relative telomeric repeat content (RTC) in the liver was measured before and after IFN therapy in 21 chronic hepatitis C cases. Liver samples were obtained at average intervals of 12, 75, and 32 months in eight complete responders (CRs) and one biochemical responder (BR), four CRs in whom HCC developed after an eradication of hepatitis C virus, and eight nonresponders, respectively. Telomeric repeat binding factor 1 (TRF1) was immunostained in specimens from CRs and a BR. RESULTS: Although the average RTC of 0.96 +/- 0.14 (mean +/- SD) significantly decreased to 0.85 +/- 0.12 after IFN therapy in nonresponders (P = 0.023), the value of 0.91 +/- 0.14 before IFN therapy in CRs and a BR increased significantly to 1.0 +/- 0.085 (P = 0.031). TRF1 expression was barely detectable and attenuated after IFN therapy, except in CRs developing HCC, in which frequent staining appeared, and the RTC evidently decreased from 0.97 +/- 0.11 to 0.63 +/- 0.0092 in corresponding noncancerous liver tissues. CONCLUSIONS: It is strongly suggested that successful IFN therapy blocks telomere erosion, except in rare cases in which telomere reduction continues with overexpression of TRF1. Successive RTC evaluation in the liver may distinguish a risky case from a clinically cured one.

Increased hTR expression during transition from adenoma to carcinoma is not associated with promoter methylation.

Human telomerase RNA component (hTR) expression, which increases in the majority of cancer cells with an acquisition of telomerase activity, was concomitantly evaluated with methylation status and human telomerase reverse transcriptase (hTERT) expression in colorectal cancers and precursor lesions. hTR and hTERT expressions were detected by in situ hybridization and reverse transcription following polymerase chain reaction, respectively, in 15 colonic adenomas, 19 sporadic colonic cancers at various histological stages, and 3 normal colonic mucosa samples. The methylationstatus of hTR was evaluated by methylation-specific polymerase chain reaction following restriction endonuclease digestion and direct sequencing. hTERT expression was detected in 16 of 19 cancers. hTR expression was detected in all cancers including two cases of intramucosal carcinoma. No hTR signals were detected in the normal epithelium or in the adenomas with severe atypism. CpG dinucleotides in the 5'-untranslated region of hTR were completely unmethylated from -204 to -3 and mosaically methylated from -290 to -272, irrespective of the atypism. These results suggest that hTR expression is increased at the adenoma-to-carcinoma transition stage but is not always associated with hTERT expression. Hypomethylation of the hTR promoter region is not likely to be the main mechanism regulating hTR expression.

Telomere length variation and maintenance in hepatocarcinogenesis.

BACKGROUND: Despite the recent discovery of interchromosomal telomere length variation, a role for heterogeneity in telomere maintenance has yet to be established. This study investigated the significance of telomere length variation between chromosomes with respect to the association of cancer progression and telomere length regulation. METHODS: Terminal restriction fragment (TRF) was evaluated in 20 surgically resected hepatocellular carcinoma specimens (HCC), corresponding noncancerous liver tissue specimens (NCL), and in 10 liver tissue specimens with chronic liver diseases devoid of cancer (DOC). Average TRF length (TRF-A) was defined as the point of maximum intensity. Shorter and longer TRF lengths (TRF-S and TRF-L) were defined as the length above which 90% of TRF distribution was involved. A ratio, (TRF-L-TRF-S)/TRF-A, was defined as telomere length dispersion. RESULTS: The dispersion was significantly larger in HCC than in NCL specimens (P = 0.012) and in NCL than in DOC (P = 0.048). TRF-A and TRF-S were significantly shorter in HCC than in NCL (P = 0.0026, P = 0.0010). In seven patients in whom HCC recurred within 1 year, TRF-A and TRF-S were significantly shorter than in 10 patients in whom recurrence occurred after 1 year (P = 0.018, P = 0.0097). Telomeric repeat binding factor 1 was up-regulated in HCC with elongated TRF-L, whereas expression of human telomerase reverse transcriptase was greater in HCC with a shorter TRF-S. CONCLUSIONS: These results suggest that telomere length varied through chronic liver diseases by preferentially increasing shorter telomeres, whose length is a good indicator for malignant potential of HCC. Telomere length variation may be a crucial code in telomere maintenance through hepatocarcinogenesis.

Interchromosomal telomere length variation.

Despite the recent discovery of interchromosomal telomere length variation, a role for heterogeneity in telomere maintenance has yet to be established. This study aimed to clarify relative telomere length differences between chromosomes. Combined chromosomal sorting and telomeric repeat content analysis in GM130B cells, the relative telomeric repeat content in each chromosome, were calculated. Each chromosome could be isolated except for chromosomes 1 and 2 and chromosomes 9 to 12, which were isolated in a group. Telomere length was correlated with the size of the corresponding chromosome. Concomitant relative telomeric repeat content analysis in each chromosome and terminal restriction fragment analysis using the whole genome revealed that the terminal restriction fragments of each chromosome were heterogenously distributed through the smear of the fragments. This is the first description of an association between telomere length and chromosome size.