High telomerase activity and high HTRT mRNA expression differentiate pure myxoid and myxoid/round-cell liposarcomas

Primary Orbital Liposarcoma in Li-Fraumeni Cancer Family Syndrome: A Case Report

Aims and background

The aim of this study was to describe a case of primary orbital liposarcoma in Li-Fraumeni syndrome.

Methods and study design

In July 1998 a 20-year-old woman with a histological diagnosis of orbital myxoid liposarcoma underwent surgical treatment in our department. Since the patient's family pedigree met the clinical criteria for the diagnosis of LFS, molecular analysis was performed, which resulted in a molecular profile consistent with Li-Fraumeni syndrome.

Results

The patient underwent orbital exenteration extended to the upper eyelid; surgical reconstructive steps were performed to permit placement of an orbital prosthesis. Two years after primary surgery the patient underwent a quadrantectomy with lymphadenectomy of the right axilla because of the presence of a nodule of 1.5 cm in diameter in the upper-lateral quadrant of the right breast. One year after the last surgery, the patient is disease free.

Conclusion

The diagnosis of an orbital malignancy in a young patient with a family history of cancer should suggest the presence of an underlying genetic disorder like LFS; with molecular analysis we can now determine the genetic disorder and the exact location of the mutation, and also obtain important prognostic data using specific cellular markers. More prognostic information increases the chances of adequate personalized treatment.

TERT promoter hotspot mutations are recurrent in myxoid liposarcomas but rare in other soft tissue sarcoma entities

Background

Recently, recurrent point mutations in the telomerase reverse transcriptase (TERT) promoter region have been found in many human cancers, leading to a new transcription factor binding site, increased induction of TERT and subsequently to telomere maintenance. We determined the prevalence of TERT promoter mutations in soft tissue sarcomas of 341 patients comprising 16 entities and in 16 sarcoma cell lines covering 7 different soft tissue sarcoma types.

Methods

The sarcoma tissue samples were collected from the archives of the Institute of Pathology, University of Heidelberg and were composed of 39 myxoid liposarcomas (MLS), 61 dedifferentiated liposarcomas, 15 pleomorphic liposarcomas, 27 leiomyosarcomas, 25 synovial sarcomas (SS), 35 malignant peripheral nerve sheath tumors (MPNST), 40 undifferentiated pleomorphic sarcomas, 17 myxofibrosarcomas, 9 low grade fibromyxoid sarcomas, 10 cases of dermatofibrosarcoma protuberans, 31 solitary fibrous tumors (SFT), 8 extraskeletal myxoid chondrosarcomas, 9 angiosarcomas, 6 alveolar soft part sarcomas, 5 clear cell sarcomas and 4 epithelioid sarcomas. Sarcoma cell lines were obtained from the raising laboratories. A 193 bp fragment of the TERT promoter region covering the hot-spot mutations C228T and C250T was amplified, and direct sequencing of the PCR products was performed.

Results

TERT promoter mutations were detected in 36/341 sarcomas. They were highly recurrent in MLS (29/39; 74%) and were in the present MLS series not associated with the phenotype (myxoid vs. round cell variant), tumor grade, tumor site and patients’ median age or gender. In the remaining cases, TERT promoter mutations were found only in 7/302 sarcoma samples and confined to SFTs (4/31; 13%), MPNSTs (2/35; 6%), and SSs (1/25; 4%). Within the collection of sarcoma cell lines examined, TERT promoter mutations were detected in two MLS and in one of three MPNST cell lines.

Conclusions

TERT promoter mutations are frequent in MLSs including their round cell variants, representing the most prevalent mutation identified in this sarcoma entity to date, and in a minor fraction of SFTs, MPNSTs and SSs. The majority of sarcomas are devoid of TERT promoter hotspot mutations. These data suggest that telomere maintenance through increased expression of telomerase plays an important role in the pathogenesis especially of MLS.

Correlation between p38 mitogen-activated protein kinase and human telomerase reverse transcriptase in sarcomas

Background

One of the major components of telomerase is the human telomerase reverse transcriptase (hTERT) as the catalytic protein. hTERT mRNA expression are reported to be associated with prognosis and tumor progression in several sarcomas. However, there is no clear understanding of the mechanisms of hTERT in human sarcomas. Recent studies have suggested that signals transmitted through p38 mitogen-activated protein kinase (MAPK) can increase or decrease hTERT transcription in human cells. The purpose of this study was to analyse the correlation between p38 MAPK and hTERT in sarcoma samples.

Methods

We investigated 36 soft tissue malignant fibrous histiocytomas (MFH), 24 liposarcomas (LS) and 9 bone MFH samples for hTERT and p38 MAPK expression. Quantitative detection of hTERT and p38 MAPK was performed by RT-PCR.

Results

There was a significant positive correlation between the values of hTERT and p38 MAPK in all samples (r = 0.445, p = 0.0001), soft tissue MFH (r = 0.352, p = 0.0352), LS (r = 0.704, p = 0.0001) and bone MFH samples (r = 0.802, p = 0.0093). Patients who had a higher than average expression of p38 MAPK had a significantly worse prognosis than other patients (p = 0.0036).

Conclusions

p38 MAPK may play a role in up-regulation of hTERT, and therefore, p38 MAPK may be a useful marker in the assessment of hTERT and patients' prognosis in sarcomas.

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.

The promise of telomere length, telomerase activity and its regulation in the translocation-dependent cancer ESFT; clinical challenges and utility

The Ewing's sarcoma family of tumours (ESFT) are diagnosed by EWS-ETS gene translocations. The resulting fusion proteins play a role in both the initiation and maintenance of these solid aggressive malignant tumours, suppressing cellular senescence and increasing cell proliferation and survival. EWS-ETS fusion proteins have altered transcriptional activity, inducing expression of a number of different target genes including telomerase. Up-regulation of hTERT is most likely responsible for the high levels of telomerase activity in primary ESFT, although telomerase activity and expression of hTERT are not predictive of outcome. However levels of telomerase activity in peripheral blood may be useful to monitor response to some therapeutics. Despite high levels of telomerase activity, telomeres in ESFT are frequently shorter than those of matched normal cells. Uncertainty about the role that telomerase and regulators of its activity play in the maintenance of telomere length in normal and cancer cells, and lack of studies examining the relationship between telomerase activity, regulators of its activity and their clinical significance in patient samples have limited their introduction into clinical practice. Studies in clinical samples using standardised assays are critical to establish how telomerase and regulators of its activity might best be exploited for patient benefit.

Telomerase activity is a biomarker for high grade malignant peripheral nerve sheath tumors in neurofibromatosis type 1 individuals

Telomerase activity (TA) and the expression of its enzymatic subunits, which have been demonstrated in many tumors, remain poorly investigated in tumors associated with neurofibromatosis type 1 (NF1). In this study, we analysed the association of TA and the expression of telomerase RNA (TR) and telomerase reverse transcriptase (TERT) in 23 malignant peripheral nerve sheath tumors (MPNST) (17 high grade and 6 low grade tumors), 11 plexiform neurofibromas (PNF) and 6 dermal neurofibromas (DNF). TA was studied using telomerase repeat amplification protocol (TRAP) assay and expression of TR and TERT was investigated using reverse transcription PCR (RT-PCR) and real-time PCR. TA was detected in 14 out of 17 (82%) high grade MPNST, whereas all 6 low grade MPNST and 17 benign tumors were telomerase negative. The TERT transcripts were detected in all high grade MPNST, 50% of the low grade MPNST, and 4 benign tumors. However, the expression level of the TERT strikingly correlated with TA and high grade MPNST. Thus, while TERT expression was similar in both low grade MPNST and PNF (P = 0.115), it was significantly higher in high grade MPNST when compared to either low grade MPNST (P = 0.042), PNF (P = 0.001) or DNF tumors (P = 0.010). These findings indicate that TA and expression level of TERT are potential markers for high grade malignancy in NF1 patients.

Expression of human telomerase reverse transcriptase in gastrointestinal stromal tumors occurs preferentially in malignant neoplasms

Telomerase is expressed in many human cancers and cell lines and is thought to contribute to their immortality. To date, little is known about the expression of telomerase in nonepithelial tumors. The objective of this study was to evaluate the expression of human telomerase reverse transcriptase (hTERT) in gastrointestinal stromal tumors (GISTs). Twenty-three GISTs (9 low malignant potential, 10 primary malignant, and 4 intra-abdominal recurrences) were evaluated for hTERT expression by using immunohistochemistry on tissue microarray. Tissue blocks were retrieved, and hematoxylin and eosin stains were performed to evaluate the histological tumor type. All cases were strongly positive for KIT (CD117). Immunohistochemistry for hTERT was performed. Eight of 9 cases of the low malignant potential group were negative for hTERT immunoexpression, whereas all malignant GISTs showed positive staining that varied from weak to strong immunoreactivity. Six of 10 cases of the primary malignant GISTs were strongly positive for hTERT. The remaining cases (4/10) showed weak staining. All recurrent GISTs (4/4) showed strong positive immunostaining for hTERT. One malignant case was weakly positive for hTERT, but its recurrence was strongly positive. These results suggest that hTERT expression occurs preferentially in malignant tumors and that telomerase activity may occur during the progression of GISTs. Immunohistochemical staining for hTERT may be a useful marker for the prognostication of GISTs.

Telomerase as tumor marker

Telomerase, a critical enzyme responsible for continuous cell growth, is repressed in most somatic cells except proliferating progenitor cells and activated lymphocytes, and activated in approximately 85% of human cancer tissues. Telomerase activity is a useful cancer-cell detecting marker in some types of cancers in which almost all cases show telomerase activation. In other types in which telomerase becomes upregulated according to tumor progression, it is a useful prognostic indicator. Detection of human telomerase reverse transcriptase (hTERT) mRNA or protein in various clinical samples is also applicable. However, careful attention should be paid to the false negative results due to the instability of this enzyme or hTERT mRNA and the existence of polymerase chain reaction inhibitors as well as the false-positive results due to the contamination by normal cells with telomerase activity. If these pitfalls are avoided, in situ detection of hTERT mRNA or protein will facilitate the reliability of telomerase as a tumor marker.

Elevated telomerase activity, c-MYC-, and hTERT mRNA expression: association with tumour progression in malignant lipomatous tumours

The role of telomerase activity in tumour progression of liposarcomas is not well understood. Therefore, we investigated 72 liposarcomas of different histological subtypes for an association between telomeric lengths and telomerase activity, and assessed the association between the catalytic subunit human telomerase reverse transcriptase (hTERT) and its activator c-MYC. Telomeric repeat fragment lengths were determined using radioactive DNA-fingerprint analysis with the telomere-specific probe (TTAGGG)(3), whereas telomerase activity was ascertained using the non-radioactive TRAP-assay. To evaluate the expression of hTERT and c-MYC, we applied real-time RT-PCR using a LightCycler. Eight tumours were investigated by microdissection. The MIB1-proliferation index and hTERT and c-MYC protein expression were determined immunohistochemically. Genetic alterations showed a high degree of tumour specificity. Highly malignant myxoid/round cell liposarcomas showed the longest telomeres, the strongest telomerase activity, and the highest hTERT and c-MYC expression levels compared with the pure myxoid variants (p < 0.001), which are of low malignancy. Pleomorphic liposarcoma was characterized by zero or low hTERT and c-MYC expression and telomerase activity, but long telomeres, underlining their different pathogenetic pathway. Elevated gene expression was accompanied by protein immunopositivity. MIB1-proliferation index did not correlate with other molecular markers. We conclude that hTERT and c-MYC expression are associated with telomerase activity in liposarcomas. Elevated hTERT and c-MYC expression as well as high telomerase activity play a role in the tumour progression of this sarcoma type. Nevertheless, each histological subtype of liposarcomas is defined by a specific molecular pattern. Telomerase activation is the most common pathway in liposarcomas maintaining telomeric length.

Full-length telomerase reverse transcriptase messenger RNA is an independent prognostic factor in neuroblastoma

Telomerase activity (TA) is the most recently recognized prognostic factor in neuroblastoma, and its outstanding predictive power was documented by several studies. However, TA measurements require fresh tumor tissue that is not always available in daily clinical practice. We previously described a reverse transcriptase-polymerase chain reaction assay that we used to investigate the possible prognostic relevance of the telomerase catalytic subunit, hTERT, at the mRNA level. Because hTERT mRNA undergoes alternative splicing as a regulatory mechanism of TA, we discriminated between truncated and full-length hTERT transcripts. In a retrospective study on 124 neuroblastomas, 56 (45.2%) tumors showed spliced hTERT transcripts, whereas 30 (24.2%) contained full-length hTERT transcripts. The presence of both spliced and full-length hTERT transcripts was significantly associated with MYCN amplification. hTERT in general showed no correlation to other prognostic factors, ie, International Neuroblastoma Staging System stage, International Neuroblastoma Pathology classification grade, or age at diagnosis, whereas the presence of full-length transcripts was significantly associated with higher stages. The presence of any hTERT transcripts carried no significant prognostic information, yet full-length hTERT transcripts were highly predictive of poor outcome (P < 0.0001). In a multivariate analysis, full-length hTERT transcripts and International Neuroblastoma Pathology classification grade emerged as the sole independent predictors of event-free survival, with relative risks of 10.0 and 3.9, respectively. The strong statistical correlation of full-length hTERT transcripts with clinical outcome in neuroblastoma suggests that the reverse transcriptase-polymerase chain reaction analysis of hTERT transcripts may be equatable to TA measurements. Because this assay is well suited for archival material, it could become a useful adjunct in evaluating the prognosis of individual neuroblastoma cases.

Telomerase activity and human telomerase reverse transcriptase mRNA expression are correlated with clinical aggressiveness in soft tissue tumors

BACKGROUND

Telomerase is a ribonucleoprotein enzyme that extends telomere specific repeats on the ends of chromosomes. Telomerase activity has been detected frequently in various types of human tumors and has been associated with cell immortality and oncogenesis. Human telomerase reverse transcriptase (hTERT), a telomerase catalytic subunit, reportedly regulates telomerase activity. Little is known about telomerase activity and hTERT mRNA expression in soft tissue tumors. The objective of this study was to clarify the correlation between these two parameters and clinical aggressiveness in soft tissue tumors.

METHODS

In 41 surgically resected soft tissue tumors, telomerase activity was measured by the fluorescence-based telomeric repeat-amplification protocol and hTERT mRNA expression was determined by real-time polymerase chain reaction.

RESULTS

Telomerase activity was detected in 52% of sarcomas and in none of the benign soft tissue tumors (P < 0.05). Telomerase activity was found in 77% of 13 locally recurrent sarcomas and in 89% of 9 sarcomas with distant metastasis. The frequency of the presence of telomerase activity in those tumors was significantly greater compared with the frequency of telomerase activity in the other sarcomas (P < 0.05 and P < 0.01, respectively). All telomerase positive sarcomas expressed hTERT mRNA. The mean level of hTERT mRNA expression in sarcomas was significantly greater compared with the mean hTERT mRNA expression level in benign tumors (P < 0.05) and in locally recurrent sarcomas compared with primary sarcomas (P < 0.001).

CONCLUSIONS

The results of the current study suggest that the detection of telomerase activity and the level of hTERT mRNA expression are useful markers for evaluating the clinical aggressiveness in soft tissue tumors.

Telomerase activity and hTERT mRNA expression can be heterogeneous and does not correlate with telomere length in soft tissue sarcomas

In a previous study, we showed that telomerase activity (TA) and human telomerase reverse transcriptase (hTERT) mRNA expression were undetectable in benign mesenchymal lesions and low-grade soft tissue sarcomas (STSs), but detectable in about 50% of intermediate-/high-grade STSs. We wondered if this lack of TA or hTERT mRNA expression could be related to the tumor sample examined and if there was a relationship between the former 2 parameters and telomere length. Two separate tumor samples from 37 STSs were examined for telomerase activity, using the telomerase repeat amplification protocol (TRAP) assay and for hTERT mRNA expression, using RT-PCR. Telomere length was determined in each tumor sample, using the terminal restriction fragments (TRF) technique. Significant variations in telomere length, TA and hTERT mRNA expression between 2 samples of the same tumor were observed in 27%, 11% and 27% of STSs, respectively. Telomere length did not correlate with TA or hTERT mRNA expression. Despite great intratumoral heterogeneity in telomere length, short and long telomeres were more often seen in the low/intermediate-grade and high-grade STS categories, respectively. Few STSs that showed a TRF pattern suggestive of alternative lengthening of telomeres (ALT) may contain ALT subpopulations.

Co-expression of survivin and TERT and risk of tumour-related death in patients with soft-tissue sarcoma

Increased expression of survivin has been shown to be a negative predictor of survival in patients with soft-tissue sarcoma. We investigated 89 adults with soft-tissue sarcomas to ascertain the relation between co-expression of survivin and human telomerase reverse transcriptase (TERT) transcripts and prognosis. We quantified mRNA expression of survivin and TERT transcripts. Cox's proportional-hazards regression model showed co-expression of both genes to be a significant negative prognostic factor for patients with stage I to stage IV tumours (p=0 small middle dot0004; relative risk 20 small middle dot1, 95% CI 3 small middle dot8-106 small middle dot4) and for those at stage II and III (p=0 small middle dot0002; 42 small middle dot1, 6 small middle dot0-294 small middle dot9) compared with low expression of both genes. Co-expression of survivin and TERT transcripts identifies patients at high risk of tumour-related death.

Clinical utility of telomerase in cancer

This review will focus on the clinical utilities of telomerase for human cancer diagnosis. Much attention has been focused on detection of telomerase activity and its essential components (hTR and hTERT) in cancer and noncancerous tissues. Expression of hTR and hTERT is upregulated in almost all human malignant tumors but not in benign or normal tissues with the exception of germline cells, proliferative stem cells, activated lymphocytes, and certain benign tumors. Thus, telomerase is a useful marker for cancer diagnosis and in some instance as a prognostic indicator of outcome. Telomerase detection in cells derived from breast fine needle aspirates, bronchial washes, and pancreatic juices show high sensitivity and specificity for cancer detection. In tissue samples, the level of telomerase activity is a useful prognostic indicator in certain adult cancers such as gastric and colon cancers and in neuroblastomas. Immunohistochemical detection of hTERT will facilitate exact diagnosis of the telomerase positive cells and expand the application of telomerase in cancer diagnosis.

Telomerase activity, Ki-67, cyclin D1 and A expression, and apoptosis in solitary fibrous tumors: additional features of a predictable course?

Solitary fibrous tumors (SFTs) are infrequent soft tissue neoplasms which are usually benign and surgically curable. However, their behavior is not always predictable, although several clinical and pathological criteria of malignancy have been established. In many cancers, including some soft tissue tumors, telomerase activity (TA) has been shown to be a new reliable pathological marker of malignancy. Overexpression of some cyclins is associated with higher degrees of malignancy and predictive of the clinical course. In this study, we evaluated TA, mitotic and apoptotic indices (MI, AI), and the expression of Ki-67, cyclins D1 and A in five typical and two clinicopathologically atypical SFTs, the latter two of which had also recurred. High TA was demonstrated in the two atypical cases, which also showed a higher labeling index to Ki-67, as well as higher cyclin D1 and A expression, and either none or very few apoptoses. We suggest that TA, Ki-67, cyclin expression, and AI be evaluated in SFTs as possible adjunctive pathological criteria of behavior.

Presence of telomerase activity in different musculoskeletal tumor histotypes and correlation with aggressiveness

Telomerase is a ribonucleoprotein enzyme that maintains the protective structures at the ends of eukaryotic chromosomes, called telomeres. Telomerase activity was observed and correlated with aggressiveness in different neoplasms such as breast, prostate, blood and brain cancers, among others. To investigate whether telomerase activity is an index of aggressiveness in bone and soft tissue lesions of the extremities, 66 biopsy samples from our tissue bank were studied. These samples included 43 high-grade sarcomas, 9 aggressive benign tumors and 14 totally benign lesions. The samples were collected from patients homogeneously treated at the Rizzoli Orthopaedic Institute with a follow-up ranging from 4 to 11 years (median, 7 years). A non-radioactive polymerase chain reaction-based enzyme-linked immunosorbent assay was used for the study. All tumors investigated were positive for telomerase activity. Among benign lesions, only 2 aneurysmal bone cysts showed higher telomerase activity than the cut-off point, whereas all the other benign lesions had lower activity. Our results indicate that high levels of telomerase activity in bone and soft tissue lesions correlate with more aggressive clinical behavior in patients treated with surgery alone. An interesting inverse correlation between telomerase activity and occurrence of pulmonary metastasis was detected in osteosarcoma patients treated with chemotherapy. A parallel increase of telomerase activity and malignancy was observed in the adipose and cartilagineous tissue lesions. Our data suggest that telomerase activity could be considered a marker of tumor aggressiveness for bone and soft tissue lesions. The results obtained in osteosarcoma samples suggest that low levels of telomerase activity may be predictive of the prognosis and should influence the therapeutic protocol.

Analysis of human telomerase reverse transcriptase mRNA (hTERT) expression in myxoid liposarcomas using LightCycler real-time quantitative reverse transcriptase-polymerase chain reaction

We describe a convenient, nonradioactive reverse transcription--polymerase chain reaktion (RT-PCR) method for the rapid and accurate quantitative detection of the human telomerase catalytic subunit human telomerase reverse transcriptase (hTERT) mRNA. The LightCycler TeloTAGGG hTERT Quantification Kit (Roche Molecular Biochemicals) was designed to be used for the highly sensitive and quantitative detection of hTERT mRNA relative to the house-keeping gene porphobilinogen deaminase (PBGD). As a tumor progression model, we investigated 26 myxoid liposarcomas (11 pure myxoid grade I, 15 myxoid/round cell grade II/III) for the hTERT expression level and compared the results of the new method with former measurements performed in silver-stained polyacrylamide gels. Both methods revealed similar results, with real-time RT-PCR being the more accurate quantification technique, which also saves time and material. Elevated hTERT expression (cut-off ratio x 100 at 1.3) was an indicator of round cell components and hence for tumor progression in myxoid liposarcoma. The new method is capable of differentiating between pure myxoid and myxoid/round cell liposarcomas for hTERT-expression more accurately.