Detection of telomerase activity in breast masses by fine-needle aspiration

Telomerase activity and telomere length in women with breast cancer or without malignancy: A systematic review and meta-analysis

AIM

We performed a systematic review and meta-analysis to assess whether telomerase activity and telomere length are associated with breast cancer.

METHODS

PubMed, Web of Science, Embase, LILACS, Scielo, Embase, and CNKI databases were searched to obtain relevant articles published through May 10, 2023, following PRISMA guidelines and a registered PROSPERO protocol (CRD42022335402). We included observational studies reporting telomerase activity or telomere length in patients with breast cancer compared with women with benign lesions or normal tissue (control women). The Newcastle-Ottawa Scale was used to evaluate the quality of studies. Data were expressed as odds ratios (OR) and 95 % confidence intervals (CI). Random effects and inverse variance methods were used to meta-analyze associations. The I2 test was used to assess heterogeneity.

RESULTS

The meta-analysis of telomerase shows significantly greater activity in patients with breast cancer than in those without malignancies (OR = 23.46, 95 % CI 14.07-39.11, p < 0.00001, I2 = 72 %). There were non-significant differences in relative telomere length (OR = 1.16, 95 % CI = 0.90-1.49, p = 0.26, I2 = 86 %) and leukocyte telomere length (OR = 2.32, 95 % CI = 0.89-6.08, p = 0.09, I2 = 98 %) between women with and without breast cancer. In subgroup analyses by world regions of studies, both telomerase activity and telomere length displayed the same trends as in their respective meta-analyses. In sensitivity analyses, variables showed their respective same trends.

CONCLUSION

Telomerase activity is higher in patients with breast cancer than in women without malignancies. There were no significant differences in either relative telomere length or leukocyte telomere length in women with and without breast cancer. PROSPERO protocol CRD42022335402.

Telomere fusion threshold identifies a poor prognostic subset of breast cancer patients

Telomere dysfunction and fusion can drive genomic instability and clonal evolution in human tumours, including breast cancer. Telomere length is a critical determinant of telomere function and has been evaluated as a prognostic marker in several tumour types, but it has yet to be used in the clinical setting. Here we show that high‐resolution telomere length analysis, together with a specific telomere fusion threshold, is highly prognostic for overall survival in a cohort of patients diagnosed with invasive ductal carcinoma of the breast (n = 120). The telomere fusion threshold defined a small subset of patients with an extremely poor clinical outcome, with a median survival of less than 12 months (HR = 21.4 (7.9–57.6), P < 0.0001). Furthermore, this telomere length threshold was independent of ER, PGR, HER2 status, NPI, or grade and was the dominant variable in multivariate analysis. We conclude that the fusogenic telomere length threshold provides a powerful, independent prognostic marker with clinical utility in breast cancer. Larger prospective studies are now required to determine the optimal way to incorporate high‐resolution telomere length analysis into multivariate prognostic algorithms for patients diagnosed with breast cancer.

High‐resolution telomere length analysis is highly prognostic for overall survival.

Independent of ER, PGR, HER2 status, NPI and grade.

Dominant variable in multivariate analysis.

Prevalence of telomerase activity in human cancer

Telomerase activity has been measured in a wide variety of cancerous and non-cancerous tissue types, and the vast majority of clinical studies have shown a direct correlation between it and the presence of cancerous cells. Telomerase plays a key role in cellular immortality and tumorigenesis. Telomerase is activated in 80-90% of human carcinomas, but not in normal somatic cells, therefore, its detection holds promise as a diagnostic marker for cancer. Measurable levels of telomerase have been detected in malignant cells from various samples: tissue from gestational trophoblastic neoplasms; squamous carcinoma cells from oral rinses; lung carcinoma cells from bronchial washings; colorectal carcinoma cells from colonic luminal washings; bladder carcinoma cells from urine or bladder washings; and breast carcinoma or thyroid cancer cells from fine needle aspirations. Such clinical tests for telomerase can be useful as non-invasive and cost-effective methods for early detection and monitoring of cancer. In addition, telomerase activity has been shown to correlate with poor clinical outcome in late-stage diseases such as non-small cell lung cancer, colorectal cancer, and soft tissue sarcomas. In such cases, testing for telomerase activity can be used to identify patients with a poor prognosis and to select those who might benefit from adjuvant treatment. Our review of the latest medical advances in this field reveals that telomerase holds great promise as a biomarker for early cancer detection and monitoring, and has considerable potential as the basis for developing new anticancer therapies.

Telomerase detection in the diagnosis and prognosis of cancer

Telomerase, a critical enzyme responsible 'for cellular immortality, is usually repressed in somatic cells except for lymphocytes and self-renewal cells, but is activated in approximately 85% of human cancer tissues. The human telomerase reverse transcriptase (hTERT) is the catalytic component of human telomerase. In cancers in which telomerase activation occurs at the early stages of the disease, telomerase activity and hTERT expression are useful markers for the detection of cancer cells. In other cancers in which telomerase becomes upregulated upon tumor progression, they are useful as prognostic indicators. However, careful attention should be paid to false-negative results caused by the instability of telomerase and of the hTERT mRNA and the presence of PCR inhibitors, as well as to false-positive results caused by the presence of alternatively spliced hTERT mRNA and normal cells with telomerase activity. Recently, methods for the in situ detection of the hTERT mRNA and protein have been developed. These methods should facilitate the unequivocal detection of cancer cells, even in tissues containing a background of normal telomerase-positive cells.

Detection of telomerase activity in high concentration of cell lysates using primer-modified gold nanoparticles

Although the telomeric repeat amplification protocol (TRAP) has served as a powerful assay for detecting telomerase activity, its use has been significantly limited when performed directly in complex, interferant-laced samples. In this work, we report a modification of the TRAP assay that allows the detection of high-fidelity amplification of telomerase products directly from concentrated cell lysates. Briefly, we covalently attached 12 nm gold nanoparticles (AuNPs) to the telomere strand (TS) primer, which is used as a substrate for telomerase elongation. These TS-modified AuNPs significantly reduce polymerase chain reaction (PCR) artifacts (such as primer dimers) and improve the yield of amplified telomerase products relative to the traditional TRAP assay when amplification is performed in concentrated cell lysates. Specifically, because the TS-modified AuNPs eliminate most of the primer-dimer artifacts normally visible at the same position as the shortest amplified telomerase PCR product apparent on agarose gels, the AuNP-modified TRAP assay exhibits excellent sensitivity. Consequently, we observed a 10-fold increase in sensitivity for cancer cells diluted 1000-fold with somatic cells. It thus appears that the use of AuNP-modified primers significantly improves the sensitivity and specificity of the traditional TRAP assay and may be an effective method by which PCR can be performed directly in concentrated cell lysates.

Transduction of E2F-1 TAT fusion proteins represses expression of hTERT in primary ductal breast carcinoma cell lines

Background

Telomerase expression is detectable in 81–95% of breast carcinomas and may serve as a therapeutic target. The objective of this study was to investigate repression of telomerase activity in primary ductal breast cancer cells through transcriptional regulation of the catalytic subunit hTERT. We hypothesized that inhibition of telomerase expression could be achieved via Tat mediated protein transduction of the repressor protein E2F-1.

Methods

Protein purification techniques were refined to yield biologically active Tat fusion proteins (TFPs) capable of transducing the breast cancer cell lines HCC1937 and HCC1599. Cell lines were treated with wildtype E2F-1 (E2F-1/TatHA), mutant E2F-1 (E132/TatHA) and a control Tat peptide (TatHA) for 24 hours. Total RNA was isolated from treated cells, reverse transcribed and fold changes in gene expression for hTERT determined via real-time RT-qPCR.

Results

Significant repression of the catalytic subunit of telomerase (hTERT) was present in both HCC1937 and HCC1599 cells following treatment with E2F-1/TatHA. In HCC1937 cells, hTERT was repressed 3.5-fold by E2F-1/TatHA in comparison to E132/TatHA (p < 0.0012) and the TatHA peptide controls (p < 0.0024). In HCC1599 cells, hTERT was also repressed with E2F-1/TatHA treatment by 4.0-fold when compared to the E132/TatHA control (p < 0.0001). A slightly lower hTERT repression of 3.3-fold was observed with E2F-1/TatHA in the HCC1599 cells when compared to the TatHA control (p < 0.0001).

Conclusion

These results suggest that transduction of E2F-1/TatHA fusion proteins in vitro is an effective repressor of hTERT expression in the primary ductal breast cancer cell lines HCC1937 and HCC1599.

Telomerase Activity in Giant Cell Tumors of Bone

BACKGROUND

A giant cell tumor of bone (GCT) is a histologically benign neoplasma that has an unpredictable pattern of biological aggressiveness. In the present study, we investigated whether there was a correlation between telomere length or the levels of telomerase activity and other clinical features of GCTs, for the possible use of these factors as parameters of aggressiveness or prognosis.

METHODS

In 16 surgically resected GCTs specimens, telomere length was assessed by terminal restriction fragments by Southern blot analysis. Telomerase activity was measured by a semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol assay.

RESULTS

Telomere length reduction was observed in 69% of the GCT samples. The telomere lengths of tumors were significantly shorter than those of normal tissue (P = .008). The mean telomere length of grade 3 tumors was significantly shorter than those of grade 1 and 2 tumors (P = .038). Telomerase activity was detected in 81% of tumor samples. The level of telomerase activity in tumors with local recurrence was significantly higher than in tumors without local recurrence (P = .011).

CONCLUSIONS

These results suggest that telomere length correlates with roentgenographic grade as a result of the frequency of cell division, and high telomerase activity indicates the aggressiveness of GCTs.

Telomerase in breast cancer: a critical evaluation

Human chromosomes have highly specialized structures at their ends termed telomeres, repetitive, non-coding DNA sequences (5'-TTAGGG-3'), ranging in size from 5 to 20 kb in human cells. These highly specialized structures prevent chromosome ends from being recognized as double-strand DNA breaks, and they also provide protection from destabilizing agents. The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences lost during replication by using an intrinsic RNA component as a template for polymerization. Telomerase has two core functional components required for its activity: the catalytic subunit of human telomerase reverse transcriptase (hTERT) and a telomerase RNA template (hTR). Telomerase is activated in the majority of immortal cell lines in culture and in most malignant tumors. This review outlines our current understanding of telomerase in breast cancer development and critically evaluates potential utilities in diagnosis, prognosis, and therapy.

Analysis of telomerase activity and detection of its catalytic subunit, hTERT

The discovery of the enzyme telomerase and its subunits has led to major advances in understanding the mechanisms of cellular proliferation, immortalization, aging, and neoplastic transformation. The expression of telomerase in more than 85% of tumors provides an excellent tool for the diagnosis, prognosis, and treatment of cancer. However, the techniques employed in its detection appear to play a significant role in the interpretation of the results. The telomeric repeat amplification protocol (TRAP assay) has been the standard assay in the detection of telomerase activity and many variations of this technique have been reported. Recent advances in the development of the TRAP assay and the incorporation of techniques that provide a quantitative and qualitative estimate of telomerase activity are assessed in this review. In addition to histological and cytological examination of tissues, distribution patterns of the catalytic subunit of telomerase, hTERT, are frequently used in the prognosis of tumors. The methods involved in the detection of hTERT as a biomarker of cellular transformation are also analyzed.

Telomerase in endocrine and endocrine-dependent tumors

Telomerase, the ribonucleoprotein enzyme that elongates chromosomal ends, or telomeres, is repressed in most normal somatic cells but reactivated in transformed cells to compensate for the progressive erosion of the telomeres during cell divisions. In accordance with this hypothesis, the presence of telomerase activity has been reported in more than 90% of human cancers, whereas most normal tissues or benign tumors contain low or undetectable telomerase activity. Reactivation of telomerase has also been widely reported in endocrine neoplasms and in hormone-related cancers. In the present study, we review the most recent publications on telomerase in these types of tumors. The hormonal regulation of telomerase activity and the possible strategies for cancer therapy based on the inhibition of telomerase has also been discussed.

Telomerase and oral cancer

The development of malignant neoplasms is a multistep process and it is believed that multiple genetic alterations are involved. The progression of neoplastic lesions is also characterized by reactivation of telomerase, a ribonucleoprotein complex enzyme that adds telomere repeats at the ends of chromosomes. In view of the close association between telomerase and malignancy, this molecule may prove to be a useful marker for malignancy. This review focuses on the diagnostic and therapeutic potential of telomerase. The experimental data for telomerase assays with the potential for oral cancer detection and diagnosis are also reviewed.

Alternative methods of extracting telomerase activity from human tumor samples

Telomerase activity is present in approximately 85% of malignant cancers and >30% of premalignant lesions. Extraction of telomerase from solid tumors and tissues remains difficult and inconvenient due to the presence of PCR inhibitors. Here we show that PCR inhibitors are easily removed during an initial extraction, allowing detection of telomerase activity in subsequent extractions from the same sample. In addition, telomerase activity may be enriched and detected from very small samples in a large background by utilizing a biotin/strept-avidin coated, magnetic bead retrieval assay. Our results provide alternative methods for telomerase extraction from solid tumors and small samples that are more convenient and accurate.

Detection of telomerase activity in biopsy specimens for diagnosis of biliary tract cancers

BACKGROUND

Telomerase activity is detectable in more than 85% of primary cancers. We determined telomerase activity in biopsy specimens obtained from biliary tract cancers to evaluate the clinical application of telomerase activity detection in combination with p53 immunostaining and routine histologic examination.

METHODS

Biopsy specimens obtained during percutaneous transhepatic cholangioscopy from 13 patients with cholangiocarcinoma, 3 patients with gallbladder carcinoma, and 4 patients with intrahepatic bile duct stones were evaluated by routine histologic examination, p53 immunostaining, and telomerase activity. Semiquantitative determination of telomerase activity was performed using a fluorescence-based telomeric repeat amplification protocol.

RESULTS

Thirteen of 16 specimens of malignant tissue had detectable telomerase activity, whereas no specimen of nonmalignant tissue had detectable telomerase activity. A p53 overexpression was recognized by immunostaining in 9 of 16 samples with cancers. Combining both telomerase activity and p53 overexpression resulted in the detection of all cancer with a sensitivity of 100%. There were no false-positive results by either modality (specificity 100%).

CONCLUSIONS

The detection of telomerase activity in biopsy specimens and p53 overexpression in combination with routine histologic examination may improve the diagnosis of biliary tract cancers. (Gastrointest Endosc 2000;52:380-6).

Telomerase is a highly sensitive and specific molecular marker in fine-needle aspirates of breast lesions

PURPOSE

Telomerase has been detected in a majority of human malignant tumors, making telomerase activity (TA) one key difference between mortal and immortal cells. In this study, we evaluated in blind-trial fashion the association of TA with cytologic and final clinical/pathologic diagnosis in fine-needle aspirates (FNAs) of breast lesions.

MATERIALS AND METHODS

In 172 FNAs, including 80 samples that were cytologically malignant, 18 that were atypical but not diagnostic for malignancy, and 74 that were cytologically benign, TA was determined by a modified nonradioactive telomeric repeat amplification protocol (TRAP) assay. Final diagnosis was made by pathologic examination of follow-up surgical material available for all the cytologically malignant samples, a majority of the cytologically atypical samples, and a portion of the cytologically benign samples.

RESULTS

TA was detected in 85 of 172 samples. Comparison of the cytologic and histologic diagnoses with TA showed that 80 of 87 samples from patients with breast cancer were telomerase-positive, resulting in a sensitivity of 92%. TA was found in four of five FNAs from carcinomas that were considered cytologically atypical but not diagnostic for malignancy. Eighty of 85 samples from patients with benign breast lesions were telomerase-negative, revealing a specificity of 94%. The five positive cases in this group were all fibroadenomas with low TA. Among the 18 cases with a cytologic diagnosis of atypia, there was a strong positive relationship between TRAP findings and histologic diagnosis.

CONCLUSION

The detection of TA in FNAs of breast lesions is a highly sensitive and specific marker of malignancy and may be used as an adjunct in cases with an equivocal cytologic diagnosis.

Telomerase activity in the differentiation of benign and malignant adrenal tumors

BACKGROUND

Telomerase is an RNA-dependent DNA polymerase that extends the ends of chromosomes by synthesizing the 6 oligonucleotide repeat TTAGGG and thus serves as a marker for cellular immortality. Although absent in most adult somatic tissues, telomerase activity is present in stem cells and is reactivated in nearly all primary human malignancies. In this study we sought to determine whether tumors of the adrenal glands contain telomerase activity and whether telomerase activity can be used to differentiate benign and malignant tumors of the adrenal glands.

METHODS

Tissue was obtained from 23 specimens at adrenalectomy. Adjacent normal adrenal tissue was obtained for control. All specimens were rapidly frozen and stored at -80 degrees C until assay. Telomerase activity was determined by the telomeric repeat amplification protocol (TRAP).

RESULTS

Telomerase activity was present in 5 of 23 (22%) of the adrenal tumors. All 3 malignant tumors were strongly TRAP positive. There was a single cortical adenoma that had very weak telomerase activity. The single TRAP-positive tumor of the adrenal medulla was a ganglioneuroma.

CONCLUSIONS

Benign adrenal tumors infrequently contain telomerase activity, whereas telomerase reactivation appears to be common in malignant tumors of the adrenal glands. These data suggest that determination of telomerase activity may offer a novel way to facilitate the differentiation of benign and malignant adrenal tumors.