Telomerase (hTERT) Overexpression Reveals a Promising Prognostic Biomarker and Therapeutical Target in Different Clinical Subtypes of Pediatric Acute Lymphoblastic Leukaemia

Acute Lymphoblastic Leukemia (ALL) is a neoplasm of the hematopoietic system defined as a clonal expansion of an abnormal lymphoid precursor cell. It mostly affects children under five years of age and is the most common tumor to afflict pediatric patients. The expression of the human telomerase gene (hTERT) in patients with ALL has been studied as a biomarker and could become a new therapeutic target. We evaluate the role of hTERT gene expression in ALL pediatric patients, through quantitative real-time PCR technique, and the possible correlation between hTERT expression and clinical variables: gender, age, white blood cells (WBC), gene fusions, and immunophenotyping. The analysis between healthy controls and ALL patients (N = 244) was statistically significant (p < 0.001), demonstrating hTERT overexpression in these patients. In comparison with the usual set of clinical variables, the data were not statistically significant (p > 0.05), indicating that hTERT is equally overexpressed among patients regardless of gender, age, gene fusions, and immunophenotyping. Moreover, patients who presented a higher hTERT expression level had a significant (p < 0.0001) lower overall survival rate. In summary, hTERT expression emerges as an important molecular pathway in leukemogenesis regardless patient’s clinical variables, thus, the data here presented pointed it as a valuable biomarker in pediatric acute lymphoblastic leukemia and a promising target for new therapeutic and prognostic measures.

TRIM28 is a transcriptional activator of the mutant TERT promoter in human bladder cancer

Bladder cancer (BC) has a 70% telomerase reverse transcriptase (TERT or hTERT in humans) promoter mutation prevalence, commonly at −124 base pairs, and this is associated with increased hTERT expression and poor patient prognosis. We inserted a green fluorescent protein (GFP) tag in the mutant hTERT promoter allele to create BC cells expressing an hTERT-GFP fusion protein. These cells were used in a fluorescence-activated cell sorting–based pooled CRISPR-Cas9 Kinome knockout genetic screen to identify tripartite motif containing 28 (TRIM28) and TRIM24 as regulators of hTERT expression. TRIM28 activates, while TRIM24 suppresses, hTERT transcription from the mutated promoter allele. TRIM28 is recruited to the mutant promoter where it interacts with TRIM24, which inhibits its activity. Phosphorylation of TRIM28 through the mTOR complex 1 (mTORC1) releases it from TRIM24 and induces hTERT transcription. TRIM28 expression promotes in vitro and in vivo BC cell growth and stratifies BC patient outcome. mTORC1 inhibition with rapamycin analog Ridaforolimus suppresses TRIM28 phosphorylation, hTERT expression, and cell viability. This study may lead to hTERT-directed cancer therapies with reduced effects on normal progenitor cells.

TPP1 Regulates hTERT Expression and Predicts Early Malignant Event and Prognosis of Cervical Cancer

Background: Cervical cancer is one of the most common deadly cancer in women worldwide. However, identifying specific biomarkers is still needed. Telomere-binding protein 1 (TPP1) is vital to telomerase activity. However, the role of TPP1 in cervical cancer and its association with human telomerase reverse transcriptase (hTERT) is unclear.This study aimed at exploring the role of telomere-binding protein 1 (TPP1) in cervical cancer development and progression, and potential mechanisms.Methods: Tissue samples from a total of 274 participants were enrolled for the evaluation of protein expression,156 of whom diagnosed withcervical cancers, 102 with cervical intraepithelial neoplasia (CIN) and 16 with normal cervix. In addition, in vitro cellular models with cervical cancer cell lines Hela, Siha, and C33a were transfected by TPP1-siRNAand protein expression of TPP1 and hTERT were assessed. Results: Compared with normal cervix, TPP1 expression was significantly higher in CIN-III and cervical cancers (P<0.001 for both). High expression of TPP1alone (Plog-rank=0.047)andhigh co-expression of TPP1/hTERT (Plog-rank=0.005)weresignificantly associated with worse survival of cervical cancer patients.After adjusting for well-known prognosis factors, hazard ratio was 2.03(95% confidence interval [CI] 0.99-4.16)for high expression of TPP1 and 2.01(95% CI 1.10-3.67) for high co-expression of TPP1/hTERT. TPP1 and hTERT expressions were positively correlated atall levels of cervical lesions (r=0.524, P<0.001). Knockdown of TPP1 decreased hTERT mRNA and protein expression.Conclusions: High expression of TPP1 might be an early event during cervical cancer development and could be served as apotential prognosis biomarker, especially when used together with hTERT. TPP1 might regulate hTERT expression with detailed underlying mechanisms warrant further investigation.

Antithetic hTERT Regulation by Androgens in Prostate Cancer Cells: hTERT Inhibition Is Mediated by the ING1 and ING2 Tumor Suppressors

The human telomerase is a key factor during tumorigenesis in prostate cancer (PCa). The androgen receptor (AR) is a key drug target controlling PCa growth and regulates hTERT expression, but is described to either inhibit or to activate. Here, we reveal that androgens repress and activate hTERT expression in a concentration-dependent manner. Physiological low androgen levels activate, while, notably, supraphysiological androgen levels (SAL), used in bipolar androgen therapy (BAT), repress hTERT expression. We confirmed the SAL-mediated gene repression of hTERT in PCa cell lines, native human PCa samples derived from patients treated ex vivo, as well as in cancer spheroids derived from androgen-dependent or castration resistant PCa (CRPC) cells. Interestingly, chromatin immuno-precipitation (ChIP) combined with functional assays revealed a positive (pARE) and a negative androgen response element (nARE). The nARE was narrowed down to 63 bp in the hTERT core promoter region. ARs and tumor suppressors, inhibitors of growths 1 and 2 (ING1 and ING2, respectively), are androgen-dependently recruited. Mechanistically, knockdown indicates that ING1 and ING2 mediate AR-regulated transrepression. Thus, our data suggest an oppositional, biphasic function of AR to control the hTERT expression, while the inhibition of hTERT by androgens is mediated by the AR co-repressors ING1 and ING2.

Relationship between Protein kinase C isoforms, Telomerase and Alpha- fetoprotein through PI3K/AKT/mTOR pathway in Hepatocellular carcinoma

Protein kinase C (PKC) family has been an alluring objective for new cancer drug discovery. It has been reported to regulate telomerase in several cancer types. Our team had previously used telomerase to elucidate alpha-fetoprotein (AFP) modulation in hepatocellular carcinoma (HCC). The aim of this study was to investigate the interrelationships among PKC isoforms, telomerase and AFP in HCC. PKCα and PKCδ were the most expressed isoforms in HepG2/C3A, PLC/PRF/5, SNU-387 and SKOV-3 cells. Following the upregulation of AFP using pCMV3-AFP and the human telomerase reverse transcriptase (hTERT) using a construct expressing a wild-type hTERT, and after their inhibition with all-trans retinoic acid and hTERT siRNA each respectively, we found that the expression of PKCα, PKCβI, PKCβII and PKCδ was affected by the variation of AFP and hTERT mRNA levels. An increase in AFP expression and secretion was observed after gene silencing of PKCα, PKCβ, PKCδ, and PKCε in HepG2/C3A. A similar pattern was observed in transfected PLC/PRF/5 cells, however PKCδ isoform silencing decreased AFP expression. Furthermore, telomerase activity was quantified using quantitative telomeric repeat amplification protocol. The variations in hTERT expression and telomerase activity were similar to those of AFP. Further investigation showed that PKC isoforms regulate AFP and hTERT expression levels through PI3K/AKT/mTOR pathway in HepG2/C3A and PLC/PRF/5 cells. Thus, these results show for the first time a possible interrelationship that links PKC isoforms to both AFP and hTERT via PI3K/AKT/mTOR pathway in HCC.

Potential of Naturally Derived Compounds in Telomerase and Telomere Modulation in Skin Senescence and Aging

Proper functioning of cells—their ability to divide, differentiate, and regenerate—is dictated by genomic stability. The main factors contributing to this stability are the telomeric ends that cap chromosomes. Telomere biology and telomerase activity have been of interest to scientists in various medical science fields for years, including the study of both cancer and of senescence and aging. All these processes are accompanied by telomere-length modulation. Maintaining the key levels of telomerase component (hTERT) expression and telomerase activity that provide optimal telomere length as well as some nontelomeric functions represents a promising step in advanced anti-aging strategies, especially in dermocosmetics. Some known naturally derived compounds contribute significantly to telomere and telomerase metabolism. However, before they can be safely used, it is necessary to assess their mechanisms of action and potential side effects. This paper focuses on the metabolic potential of natural compounds to modulate telomerase and telomere biology and thus prevent senescence and skin aging.

EPEN-04. SIOP EPENDYMOMA I: FINAL RESULTS, LONG TERM FOLLOW-UP AND MOLECULAR ANALYSIS OF THE TRIAL COHORT: A BIOMECA CONSORTIUM STUDY

Introduction Surgery and radiotherapy are established childhood ependymoma treatments. The efficacy of chemotherapy has been debated. We report final results of the SIOP Ependymoma I trial, with 12-year follow-up, in the context of a post-hoc analysis of more recently described biomarkers. Aims and Methods The trial assessed event free (EFS) and overall survival (OS) of patients aged three to 21 years with non-metastatic intracranial ependymoma, treated with a staged management strategy targeting maximum local control. The study also assessed: the response rate (RR) of subtotally resected (STR) disease to vincristine, etoposide and cyclophosphamide (VEC); and surgical operability. Children with gross total resection (GTR) received radiotherapy of 54 Gy in 30 daily fractions over six weeks, whilst those with STR received VEC before radiotherapy. We retrospectively assessed methylation and 1q status alongside hTERT, RELA, Tenascin C, H3K27me3 and pAKT expression. Results Between 1999 and 2007, 89 participants were enrolled, 15 were excluded with metastatic (n=4) or non-ependymoma tumours (n=11) leaving a final cohort of 74. Five- and ten-year EFS was 49.5% and 46.7%, OS was 69.3% and 60.5%. 1q gain was associated with poorer EFS (p=0.002, HR=3.00, 95%CI 1.49–6.10). hTERT expression was associated with worse five-year EFS (20.0% Vs 83.3%, p=0.014, HR=5.8). GTR was achieved in 33/74 (44.6%) and associated with improved EFS (p=0.006, HR=2.81, 95% confidence interval 1.35–5.84). There was an improvement in GTR rates in the latter half of the trial (1999-2002 32.4% versus 2003-2007 56.8%). Despite the protocol, 12 participants with STR did not receive chemotherapy. However, chemotherapy RR was 65.5% (19/29, 95%CI 45.7–82.1). Conclusions VEC exceeded the pre-specified RR of 45% in children over three years with STR intracranial ependymoma. However, cases of inaccurate stratification at treating centres highlights the need for rapid central review. We also confirmed associations between 1q gain, hTERT expression and outcome.

MicroRNA-Based Cancer Mortality Risk Scoring System and hTERT Expression in Early-Stage Oral Squamous Cell Carcinoma

We have previously constructed a novel microRNA (miRNA)-based prognostic model and cancer-specific mortality risk score formula to predict survival outcome in oral squamous cell carcinoma (OSCC) patients who are already categorized into “early-stage” by the TNM staging system. A total of 836 early-stage OSCC patients were assigned the mortality risk scores. We evaluated the efficacy of various treatment regimens in terms of survival benefit compared to surgery only in patients stratified into high (risk score ≥0) versus low (risk score <0) mortality risk categories. For the high-risk group, surgery with neck dissection significantly improved the 5-year survival to 75% from 46% with surgery only ( p < 0.001 ); a Cox proportional hazard model on time-to-death demonstrated a hazard ratio of 0.37 for surgery with neck dissection (95% CI: 0.2–0.6; p = 0.0005 ). For the low-risk group, surgery only was the treatment of choice associated with 5-year survival benefit. Regardless of treatment selected, those with risk score ≥2 may benefit from additional therapy to prevent cancer relapse. We also identified hTERT (human telomerase reverse transcriptase) as a gene target common to the prognostic miRNAs. There was 22-fold increase in the hTERT expression level in patients with risk score ≥2 compared to healthy controls ( p < 0.0005 ). Overexpression of hTERT was also observed in the patient-derived OSCC organoid compared to that of normal organoid. The DNA cancer vaccine that targets hTERT-expressing cells currently undergoing rigorous clinical evaluation for other tumors can be repurposed to prevent cancer recurrence in these high-risk early-stage oral cancer patients.